This study investigated the relation between the reaction kinetic model (two-step damage model with two different rate constants) for thermal stress-induced cell death developed by the authors and the damage function for thermal injury of epidermis proposed by Henriques. The cell lethality was related quantitatively to the damage function by three methods, in which different reaction rate constants were used to relate the cell lethality and damage function. The required time to attain the prescribed cell lethality under a constant exposure temperature was plotted together with the required time for the prescribed value of damage function. The result showed that the cell lethality and damage function had the similar tendency. Also, time?dependency of the newly defined damage function for two-step damage model was investigated for each method, and nondimensional time was induced to group the curves of damage function versus time. Finally, the damage function as a function of cell lethality was obtained for each method.

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Hyperthermia treatment is based on the clinical fact that cancer cells are more weaker than healthy cells in the temperature range of 42-43°C. We proposed a large size resonant cavity applicator system for abdominal tumors non-invasively. The prototype system did not have enough temperature rise for effective hyperthermia treatments. In this study, in order to improve the excitation efficiency of the antenna for resonating electromagnetic waves inside the cavity applicator, we developed several kinds of loop type antennas for heating experiments. First, the proposed antennas were presented. Next, experimental results of heating agar phantoms with developed antennas were discussed. From these results, we found that it is possible to non-invasively heat deep tumors in the abdominal region without contact using the proposed heating system.

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In this paper, we discussed a new heating control method using the resonant cavity applicator. We had already proposed the resonant cavity applicator for brain tumor hyperthermia treatments. In the clinic, it is very important to heat brain tumors corresponding to the size and location where it occurred. Here, a new method to control the heating location was proposed. In this method, the dielectric bolus, which is filled with a dielectric such as water, is attached to the human head. First, we presented the proposed heating method. Second, a 3-D anatomical human head model constructed from 2-D MRI images was discussed. The results of the SAR distributions using 3-D anatomical human head model were discussed. From these results, it was found that the proposed heating method was useful to control the heating location for effective hyperthermia treatments.

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This research was carried out to discuss the possibility of the new cryopreservation method without any damage to cell. This new method was performed by giving the micro electric current to plant tissue. Jerusalem Artichoke, Allium cepaand and Saxifraga stolonifera were mainly used for the plant tissue. As a result, this method could make the temperature at the release of supercooling lower in the range of 3℃ 〜12℃ and make survival under low temperature stress higher. The cytoplasm pH measurement by a fluorescence pH-ratiometry showed that the cytoplasm became acidified with the progress of cooling but that it shifted to be alkalified by the addition of micro current.

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In order to be successful cryopreservation of thick tissue, understanding of the mechanisms of cell in cryopreservation and the surrounding environment is very important. In this study, by giving the freezing direction to the cell monolayer with controlled cell orientation to simulate the organization of thick, the effect on cell viability post-thaw changes in cooling rate at various sites of thick tissue. Method, human dermal fibroblasts were cultured to be oriented on the substrate 24 x 24mm, the test samples were frozen with direction from the bottom to the tops. This time, temperature changes during freezing was measured by a thermocouple attached to three sites, bottom, middle and upper. From the cooling rate obtained from the temperature of each sites in the samples and post-thaw cell viability, the faster the controlled cooling rate, the larger the width of the upper and lower cooling rate resulted in a strong non-linear cooling curve . Cell viability also tended to decrease the survival rate is not strong enough nonlinear. Therefore, the impact on post-thaw cell viability of the difference in the average cooling rate of thick parts of the organization is small, indicating the potential to mitigate the decrease in survival due to the nonlinearity of the cooling rate.

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This paper describes a novel cryosurgical system in order to conduct cryosurgery for a small affected area. An ultrafine cryoprobe to generate a small frozen region and a refrigerant circulation system not to emit the refrigerant into atmosphere were used. This system consists of the ultrafine cryoprobe, the reservoir to store liquid refrigerant, the condenser to condense the refrigerant in vapor state and several valves. In the refrigerant recovery process, the condensed refrigerant was changed its state to room temperature by heating and returned to reservoir. HFC-23, which is alternative Freon, was used as refrigerant and the agar at 37°C was used as a cooling object to simulate a biological tissue. Moreover, this system was able to control the frozen region by using the bypass valve and its effectiveness was confirmed by the freezing experiment. In the freezing experiment, the temperature of cryoprobe surface reached at ?25°C and the frozen region of 2 mm in radius was generated in 20 seconds. Furthermore, the controllability of frozen region was also confirmed by changing the time to open bypass valve.

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A method to actively enhancing supercooling is one of most promising techniques for cryopreservation. The object of this paper is to study the effects of ultrasonic vibration on supercooling of water. In the experiments, water in a circular tube with thermocouple was cooled at constant cooling rate, with ultrasonic vibration at frequency of 1MHz. Two types of ultrasonic vibration; (a)amplitude-regulated vibration and (b)amplitude-modulated vibration, were tested by varying ultrasonic power and amplitude-modulated frequency. Regarding the case of amplitude-regulated vibration, the supercooling degree decreases with increasing ultrasonic power. On the other hand, as for amplitude-modulated vibration, weak enhancement of supercooling was found at amplitude-modulated frequency of 20-25kHz. Furthermore, it was indicated that there is optimum value of ultrasonic power for enhancing supercooling degree, since the action of ultrasonic vibration would have two aspects as to promote and reduce nucleation.

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Dielectrophoresis (DEP), the motion of polarizable particles in an electric field, has become an important tool for the transport, separation, and manipulation of cells in the field of biomedical engineering. However, DEP-based manipulations require in-channel micro-electrodes or micro-insulators to produce non-uniform electric fields. The present study introduces a novel cell manipulation technique by the use of a uniform AC electric field. In a uniform AC electric field, the DEP forces are eliminated because the value of the field gradient takes zero everywhere in the applied field. Hence, the dipole-dipole interaction forces present among cells play a major role in positioning and controlling cells to favorable sites of the micro-device. Human carcinoma (HeLa) cells were used to investigate the behavior of cells exposed to the uniform AC electric field. It has been demonstrated that cells aggregated, and formed a single structured layer between two electrodes; consisting of numerous chain-like clusters of various lengths aligned parallel to the direction of the field.

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Suspensions of Human carcinoma (HeLa) cells subjected to a high frequency AC electric field undergo a heterogeneous aggregation due to the induction of dielectrophoretic (DEP) forces on dispersed cells. In the present study, numerical simulations of cells suspensions in a uniform high frequency AC electric field based on the model of Langevin equation of particle kinetics have been performed to predict the evolution of aggregation and clustering of cells under the exposure of the uniform high frequency AC electric field. Results show that cells formed a single structured layer between two electrodes; consisting of numerous chain-like clusters of various lengths aligned parallel to the direction of the imposed AC electric field.

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When we consider to pass the particle suspension over a microelectrode, electric fields to produce a motive force are used. If the suspension has a noticeable conductivity, the electric field drives a substantial conduction current through the fluid and then the electric current generates localized Joule-heating. The resulting temperature gradient produces local conductivity and permittivity changes in the fluid. Dielectrophoretic forces will produce motion of both the fluids and the particles. Furthermore, the buoyancy force due to temperature field affects the flow field. In this paper, we study AC dielectrophoretic flow with the aid of finite element analysis software COMSOL Multiphysics which is a commercial package and can be considered to suit to simulate multiphysics.

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The characteristics of shock wave have a great potential for medical applications. Extracorporeal Shock Wave Lithotripsy is one such medical application. Recently, it is suggested that angiogenesis, Drug Delivery System and Gene Transfer using low-level shock wave. We developed small shock wave device for minimally invasive surgery. In this device, shock waves are generated by electrical discharge. We evaluated this device with visualization of shock wave and measurement of pressure. The results of visualization showed that shock wave converged toward the second focal point after 15 microsecond of electrical discharge, and this device could produce an average pressure of 2.32 MPa with standard deviation of 0.89 MPa. Then we had two experiments to investigate the effects of shock wave on biological cells by our device. In first experiment, cells exposed to shock wave were stained by Calcein-AM and PI. Cells were stained red in the small region; the size was about 1.5mm. This result showed that our device could provide effects locally. In another experiment, we investigate the variations of calcium ion concentration during shock wave irradiation. We observed calcium-ion elevation depending on shock wave irradiation.

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The imploding detonation of a propane-oxygen mixture was used to generate underwater shock waves in a steel pipe having an inner diameter of 10.9 mm. We investigated the imploding detonation waves in an approximately cone-shaped combustion chamber having a maximum inner diameter of 60 mm. The experimental results show that maximum gas pressure at the implosion center was 130 to 160 times higher than the initial gas pressure, and maximum hydraulic pressure of underwater shock waves in the steel pipe was 48 to 60 % of the maximum gas pressure at the implosion center. We found that we could completely sterilize coliform group by 6 times treatments of the underwater shock wave that maximum hydraulic pressure was about 100 MPa.

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Atherosclerosis is one of the causes of celebrovascular disorders. It is known that its preferential site is associated with a low wall shear stress (WSS) region. In this paper, in order to investigate the effects of arterial geometry on mass transport, the blood flow and solute transport in the lumen and arterial wall are modeled taking account of the multi-layered structure of arterial wall. We have applied the numerical analysis to three different patient-specific models of the common carotid arterial (CCA) bifurcation. The geometry of CCA was reconstructed from CT images. In the transport simulation, the albumin is used to represent the LDL (Low Density Lipoprotein). As a result, the albumin concentration in the arterial wall increases in the areas with low WSS, particularly the area near the apex of bifurcation or bend of vessel.

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Nebulizer treatment has been used for nasal diseases such as paranasal sinusitis, hypertrophic rhinitis and inferior concha inflammation. The effectiveness of the nebulizer treatment has been confirmed from clinical view points until now. However there are a few researches that evaluate the effect of the nebulizer treatment quantitatively, i.e., how medicinal mist transports and deposits on inflammation areas of nasal wall. Some researchers calculated intranasal transport phenomena of medicinal droplets using Computed Fluid Dynamics (CFD). However these researches analyzed a few cases. The individual difference was left out of consideration even though there were different shapes of nasal cavities and different grade of medical conditions. This study constructs three-dimensional geometry model of nasal cavity using an actual patient's CT data. The case undergoes deviated nasal septum, hypertrophic rhinitis, chronic sinusitis and bloating inferior nasal concha tumentia. This study analyzes the characteristics of airflow and medicinal droplet, especially focuses on local deposition characteristics. As a result airflow velocity and pressure drop increase in the narrowing region caused by jet effect. Inlet angle and velocity of nebulizer treatment can easily control medicinal droplet transport characteristics. The circulatory flow is able to contribute advances medicinal droplet transportation in widespread area of intranasal.

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The flatness of a cortisol diurnal rhythm may be indicative a long-term response to chronic stress, however, the association between subjective psychological stress and cortisol diurnal rhythm has not yet been well investigated in longitudinal study. In this study, the association between self-reported psychological stress and diurnal pattern of cortisol was assessed in healthy male. On the first day (day 1), participants filled out the General Health Questionnaire (GHQ) to assess the subjective psychological stress and collected saliva at four time points (8:00, 11:00, 15:00, 20:00). One week later (day2) they also collected saliva at same time points. Participants were then classified into two groups according to their GHQ-scores (0-2: Not-Distressed group, N=14; 3+: Distressed group, N=8). Salivary cortisol profiles exhibited a clear diurnal rhythm both in dayl and day2. However, the significant group difference was found only in salivary cortisol profile in day2. Distressed group showed lower cortisol decrease from 8:00 to 11:00 compared to Not-Distressed group. These results suggest that distressed male show flatter diurnal cortisol profiles than in good health but the effect of subjective psychological stress on cortisol profiles appear after one week

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In this study, we proposed a high performance oxygen supply system for growing underground construction sites for suppressing the cost and space of conventional ventilation systems. The proposed system utilizes hemoglobin as a high performance oxygen carrier, which allows in vivo blood to possess - 9mM of oxygen. The amount of dissociated oxygen from various concentrations of oxygen saturated hemoglobin solutions at an atmospheric environment was measured. It is found that hemoglobin solution needs depressurization to dissociate bound oxygen under the room temperature. Comparing the space and energy cost performances of the proposed system to that of the conventional system using ventilators, the proposed system could reduce the power demand to 23%.

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Recently, various studies have investigated cartilage tissue engineering. Implantation of chondrocytes isolated from patients and expanded in number in vitro is being used to treat patients with cartilage injuries. However, chondrocytes de-differentiate during culture with several passages, and the cartilage regenerated by implantation of de-differentiated chondrocytes may be suboptimal. Therefore, it is important to establish the method for culturing chondrocytes to re-differentiate and proliferate. A hydrodynamic environment is beneficial for culturing chondrocytes and bio-modification of culture substrate is also beneficial to improve cell cytoskeleton; however, collaborative effect of both the hydrodynamic effect and bio-modification were not studied. In this study, we investigated the synergetic effect of the fluid shear stress and the bio-modification of culture substrate. Passaged bovine articular chondrocytes were cultured in monolayers to sub-confluency. After 24 h of growth arrest, cells on the gelatin-coated glass were exposed to the fluid shear stress. Cell number and cell morphology were measured to evaluate the effect of fluid shear stress and bio-modification on the cell proliferation and differentiation.

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Microbe can move smoothly in water environment with high efficiency, which could offer new ideas for future micro machines. In this study, we investigated the spiral moving behavior of flagellum by using Stoke's theory and experimental models. We simulated euglena's fluid environment of Re number of 10-4. The optimal spiral shapes in terms of propulsive efficiency and the comparison with Stoke's theory were studied. We found that the propulsive force became bigger, as the spiral diameter increased. On the other hand, the propulsive efficiency was found to be highest when the spiral diameter was 15mm or 20mm. The reason was that the torque became bigger with larger spiral diameter, and that the propulsive force became smaller with smaller spiral diameter. Our mathematical equations based on Stoke's theory agreed accurately with the experimental results. Thus, the equations can be used for other predictions.

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The plasmodium of Physarum polycephalum is a unicellular and multinuclear giant amoeba. In the previous study, we have demonstrated that the velocity of the cell migration of the plasmodium in a one dimensional path is proportional to the length of its tubular structure. In this study, to investigate the mechanism of this phenomenon, we observed the changes in cytoplasmic streaming with the development of the tubular structure. As a result, we found that the flow rate and the amount of tolal flow of cytoplasmic streaming are dependent on the length of tubular structure. Namely, the result indicates that the cell migration of the plasmodium is promoted by the development of tubular structure, because the tubes reinforce the flow of cytoplasmic streaming and increase the amount of cytosol flows into and expands the pseudopods in the locomotive front.

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Medical image based left ventricle cardiovascular flow was simulated by combinations of optical flow based cardio wall velocity estimation and computational fluid dynamics (CFD). Medical images are obtained a part of diagnosis and they are patient specific. To expand its application, images based computational cardio simulation was suggested in this work. Medical images are based on pixels. Hence, it is facile to use an inertial Eulerian grid arrangement. The advantage of the method is absence of grid generation. Cartesian Coordinate system is directly constructed from the image. Another advantage is known for its stability because the mesh is spatially fixed Since, cardiovascular flow is dynamically triggered by heart muscular movement, identical approach was taken. The external geometry of fluid domain was subjected to movement. To Apply the external deformation, which was calculated by an optical flow algorithm Horn-Schunck Method, to CFD calculation process was initiated. The result illustrated large velocity vectors where significant deformation wan confirmed between steps. Since Horn-Schunck method is based the gradient of pixel luminosity, factious wall velocity vectors was observed even though local geometry was in stationary. Hence, Horn-Schunck method considered to be unsuited for accuracy.

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Now days in Japan, the heart-related disease is ranked as the second place of the cause of Japanese death. Among them, most diseases are more or less associated with the left ventricle (LV) functions. Therefore it is important to have an effective method to be able to evaluate the LV functions in a manner of bedside from the viewpoint of clinical applications. In this study we aim to develop such a method by combining the medical image processing and a recently developed multi-scale hemodynamic simulator to effectively evaluate the LV hemodynamic functions. Moreover, our simulation-based model is capable to provide the flow-based information in the left ventricle, and by integrating these information we can easily obtain a specific relation between the transient pressure and the volume in LV, namely, the P-V curve, which is the most popular method in evaluating the LV functions but also difficult to be implemented in bedside in a non-invasive manner. In our model, we first constructed an image-based three-dimensional LV model based on 3D echo images and then used our zero-dimensional model to modify this 3D model and calculated the pressures and flow volumetric velocities throughout the heart and the cardiovascular system. Second, we used the zero-dimensional model-based information as the boundary conditions for the three-dimensional modeling of the LV hemodynamics. Our results on the LV hemodynamics of a normal heart model indicate that the computed P-V curves enable the evaluation of physiological and pathological LV functions.

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A two-dimensional computer simulation of thrombus formation under the blood flow was carried out for a right atrium after univentricular Fontan conversion using a particle method. A thrombus formation and its growth were modeled by connection of thrombus components by hypothetical aggregation forces. As a result of simulation, a circulating flow occurred at a corner of the right atrium, and the blood was stagnant there. In the circulating and stagnant flow, a small thrombus was connected with another thrombus by hypothetical aggregation forces, and they grew to a large thrombus. A greater aggregation force caused a growth of a larger thrombus, which was a result from a balance between a fluid force and an aggregation force applied to the thrombus.

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Effects of volume reduction of the soft tissues, i.e., skin and subcutaneous tissue, at a bone prominence on the deformation of microvessels were investigated by finite element method. A hyperfoam model with viscoelasticity with Poisson's ratio of 0.1 or 0.2 was postulated to simulate a volume reduction of the soft tissues with vascular deformations under compression and stress relaxation. For the model with Poisson's ratio of 0.1, a load on the bone corner was adjusted so that the skin surface pressure on the mattress was near 10 kPa. The cross sectional area of the vessels decreased largely with a volume reduction by 75% near the midpoint of the circumference for the microvessel in the subcutaneous tissue and by 60% for that in the skin. Regional volume reduction was at most 30%. A model with Poisson's ratio of 0.2 obtained a relatively smaller deformation of microvessels. Compared with small deformations of the vascular cross sections for an incompressible hyperelastic model with viscoelasticity, it is concluded that the volume reduction of the soft tissues may play an important role to cause a pressure ulcer.

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Three-dimensional (3D) vertex model is one of successful to understand morphogenetic dynamics of multicellular tissue. In particular, a fundamental 3D vertex model to express cellular arrangement in tissue is suggested (H. Honda, J. Theol. Biol. 2004). To our knowledge, there is currently no alternative model in the 3D vertex ones to simulate the arrangement. However the effects of cell and tissue large deformations along with physical and geometrical inconsistencies impede expressing a natural vertex dynamics. In this study, we suggest a novel model in which an artificial drift of morphogenetic dynamics is attenuated, and in which the geometrical inconsistencies are removed.

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Actin filaments play critical roles in various cellular functions such as migration, division and shape control. In these activities, microscopic mechanical stretching, twisting and bending cause structural changes at the molecular level in single actin filaments. The actin filaments have a double helical structure consisting of globular actin molecules, that induces coupling behaviors between stretching and twisting of the filaments. Thus, tension acting on the filaments modulates the twisting dynamics of filaments, and may change affinity of regulatory actin-binding proteins which depend on the twisting behaviors of actin filaments. For better understanding of actin dynamics containing the tension and the actin-binding proteins, it is important to evaluate the extension-torsion coupling behaviors of actin filaments. This study evaluates the extension-torsion stiffness of single actin filament using molecular dynamics simulations. To evaluate the extension-torsion coupling behaviors, stretching and twisting Brownian motions of the filament were analyzed. The results demonstrated that the longitudinal and twisting motions of the filament exhibit a correlation. From the correlation, we evaluated the extension-torsion coupling stiffness of the filament based on statistical-mechanical theory.

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ignaling molecules expressed by osteocytes, osteoclasts and osteoblasts play important roles in adaptive bone remodeling, however, the mechanism by which these signaling pathways result in the changes of trabecular morphology still remains unclear. In this study, we propose mathematical models for trabecular remodeling considering signaling pathways, and conduct computer simulations using finite element method. Focusing on the movement of remodeling packets on the trabecular surface, we discuss the influence of signaling molecules on the morphological changes of trabeculae based on the trabecular remodeling simulation. First, higher RANKL expression rate results in the higher turnover of the bone remodeling cycle. Second, movement of the remodeling packets, formed by coupling of osteoclasts and osteoblasts, toward unnecessary trabecular bone surface area was observed in which osteoclast precursors sense low OPG concentration.

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The respiratory unit called lung parenchyma has ultimately fine and complex architecture, and is constructed from respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, where the gas exchange of oxygen and carbon dioxide takes place. We constructed some cubic models of lung parenchyma with and without alveolar duct by using phase-field method, and conducted structural analyses to examine the strain field in parenchyma during expansion. The frequency distribution of 1st principal strain showed that the existence of alveolar duct result in slight change of strain distribution. On the other hand, it is found that the elements in the vicinity of alveolar mouths have relatively high value of 1st principal strain, which is one of the measures for the rupture of alveolar walls.

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This paper describes a measurement method for the in-plane thermal conductivity of Printed Circuit Boards (PCBs). We designed two types of PCBs with several wiring patterns on their surfaces. This means copper amount on the PCBs is different. We measured their effective thermal conductivity in thickness direction to investigate the effects of the wiring patterns on the in-plane thermal conductivity of the PCBs. One is normal PCBs and the other is about 18 times larger PCBs than the normal PCBs. The experimental results showed that the thermal conductivity of normal PCBs was not dependent on the wiring patterns. On the other hand, the thermal conductivity of larger PCBs increased with increasing amount of copper wire due to the heat diffusion in in-plane direction by copper wires. We concluded that the effect of the wiring patterns on the in-plane thermal conductivity can be observed with our measurement method. We also performed Computational Fluid Dynamics (CFD) analysis and clarified the correlation between amount of copper wire and in-plane thermal conductivity of the PCB.

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This paper presents an experimental study on a pulsating heat pipe (PHP) with lmm square 41 meandering grooves using butane as a working fluid. The length, width and thickness of the heat pipe are 300mm, 50mm and 1.9mm, respectively. The evaporator surface area was varied by changing the evaporator length in the experiment. The following conclusions were obtained from the experiment. (1) The maximum heat transfer rate ana? was rapidly decreased when the evaporator surface area was decreased. (2) When the heat pipe has an adiabatic section at the heat pipe edge next to the evaporator, the maximum heat transfer rate Q_was increased comparing with the case of no adiabatic section at the heat pipe edge. (3)The heat transfer coefficient in the evaporator was around 1500W/m^2K not depending on the heat flux and the heat transfer coefficient in the condenser was 200-1500 W/m^2K depending on the heat flux.

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Two rectangular block-like elements as an electronic module are positioned in a parallel-walled channel and cooled by forced convection airflow. A metal plate without holes as a barrier was put in front of the modules, which is intended to function as a cover for protecting them from mechanical or electromagnetic damage, or as a thermal control device. Per-module heat transfer coefficients in the presence of the barrier of various gap, G, between the barrier and the channel and distance, L, between the module and the barrier were measured. Nusselt numbers are correlated as a function of Reynolds number and G/L.

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In this study, we fabricated microchannel for cooling of the electronic components. Microchannel was made of polydimethylsiloxane (PDMS) elastomer using soft lithography techniques. An epoxy-based photoresist (SU-8) was used as a master mold to induce soft lithography. The fabricated microchannel had a rectangular flow path with length of 24mm, width of 500pm and depth of 50vtm. We measured heat flux for water flows in the fabricated microchannel with heated plate. Water flows were laminar fully developed flow. The maximum heat flux was 44W/cm^2 for a 38K temperature difference, and flow rate of 2.0 cm^3/min. We simulate the experiment, and numerical calculation results were compared with experimental results. We clear measurements problems from the difference of experimental and numerical results.

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This paper describes visualization errors in PIV (Particle Image Velocimetry) measurement when we set the laser irradiation direction and imaging plane in the same direction. When we irradiate laser from same direction with imaging plane, angle of optical axis become less than 90°. Thus we can't focus on the particle on the measuring plane and we can't control the generation of distortion. To avoid the above problems, we employed scheimpfliig configuration on the visualization experiments and we transformed the distorted image using projective transformation. However, accuracy of PIV measurement is unknown in this condition. In this study, we focused on accuracy of PIV measurement. To discuss accuracy of PIV measurement, we designed a test model and conducted PIV measurement in the case that angles of optical axis are 90°, 60°, 45° and 30°. As a result, results of PIV measurements are in good agreement and not dependent on the angle of optical axis. It can be concluded that accuracy of PIV measurement is not dependent on angle of optical axis.

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Lithium ion battery is generally used in mobile devices and electric cars because of its advantages; high energy density, easy downsizing and environmentally friendly. On the other hand there are protection structures in the battery for the safety, and it is difficult to disassemble the battery for the health diagnosis. In this paper, a nondestructive inspection technique using inverse analysis of electromagnetic field for the lithium ion battery has been developed. This technique enable to estimate current density distribution in lithium ion battery without taking apart with boundary element method. To verify the proposed technique, numerical simulations using the nondefective battery model and the defective battery model have been conducted. The results show that the proposed technique could detect defects in the battery and be applicable to practical problems.

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Carbon nanotube have an exceptional mechanical property which could be used in the prototype nano scale actuators in nano electro mechanical systems (NEMS). CNT being a good conductor of Electricity, Heat and having Structural strength make it a perfect material for very small nano actuators. Multi walled Carbon Nano Tube (MWNT) bimorph can be modeled, fabricated and characterizedU) . A computational study of the nano actuator is done in COMSOL Multiphysis(2) in the combination of Joule heating, Thermal Expansion and Structural Mechanics. The temperature increase and deflection were examined in COMSOL Multiphysics, which is commercial software of finite element analysis. It was found that isothermal surface condition is necessary for proper bending of single material (CNT) actuator.

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The decrease in fatigue life of solder joints under the high-temperature environment is a critical issue in semiconductor packages for automotive applications. To evaluate the deterioration of solder joints under high temperature, we studied the analytical method considering the decrease in yield-stress due to the grain coarsening of solder. We found that the decrease in yield stress largely depends on the exposed temperature and the holding time by using the Sn3Ag0.5Cu solder specimen. The decreasing ratio of yield stress was determined by the degradation factor and the accumulative holding time. The predicted fatigue life of solder joints using FEM considering the decrease in yield stress agreed well with the results of thermal cycle test.

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For reliable design of the high-density electronics parts, it is very important to understand a creep strength of solders-Cu joint interface. For this purposes, in this study, a new method to prepare a miniature specimen having BGA solder balls and thin Cu wire were established. And also, creep strength were evaluated by using a newly developed creep testing machine for miniature solder specimen.

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In this work, we applied a synchrotron radiation X-ray micro-tomography system called the SP-.tCT along with a refraction-contrast imaging technique to the nondestructive evaluation of fatigue crack propagation process due to thermal cyclic loading in complex-shaped solder joints of chip type resistors mounted on FR-4 substrate. The results show that many micro-cracks appear in the thin solder layer under the chip prior to the main fatigue cracks, and using the 3D crack images, the dimensions of the crack were straightforwardly quantified by measuring the surface area of the same fatigue crack.

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Recently, the use of solder containing lead in the interconnection between printed substrate and electric packages has been prohibited, since lead may have a bad influence on human and the environment. Today Sn-Ag-Cu alloys (SnAgCu) are used in general as a substitute of Sn-Pb alloys (SnPb). However, the melting point of SnAgCu is higher than that of SnPb, which may induce damages in the substrate and packages. To solve this problem, the reflow of lead-free solder by microwave heating was studied. The results indicate that the flux has the effects to shorten the heating time and control the substrate temperature.

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The glass epoxy substrates are commonly used for printed circuit boards (PCBs). They are composed of glass fiber cloths and epoxy resins. But in many cases they are modeled as homogeneous isotropic elastic bodies because of the computational restriction.In this study, we modeled the glass cloth structures of glass epoxy substrates and carried out the thermal stress analysis of the substrate with through-hole by using large-scale FEM analysis.The result of glass cloth model analysis agreed better with the experimental result than the result of homogeneous isotropic elastic body model.

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Recently, conductive adhesives have been used as alternative to Pb-free solders. They have high heat resistance and bonded at lower temperature than Pb-free solders. Therefore, thermal fatigue life of Pb-free solder has been investigated by accelerated test based on a mechanical method. In this study, thermal and bending fatigue life of Pb-free solder and conductive adhesives was evaluated and accelerated mechanical test method was established for conductive adhesives. As a result, bending fatigue life of conductive adhesives is depends on the strain range as well as solders on this research. And fracuture mode and relative life ratio of Pb-free solder to conductive adhesives on thermal fatigue test were substituted by mechanical bending fatigue test.

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In order to establish evaluation method of thermal fatigue property on ceramic substrate, thermal cycle fatigue test and 4 point bending test were carried out using specimens of Cu/Al203. As the results, the ratio of residual strength P/Po has decreased with increasing thermal cycles. The cracks were generated on the ceramic at about corner of metal plate. Next, in order to investigate the residual stress distribution of ceramics caused by junction between ceramics and metal plate and the stress distribution of ceramics caused by thermal fatigue, FEM was carried out. As the results, it has been understood that the tensile residual stress on ceramics at about corner of metal plate is generated by the junction process and that the repetition of the tensile stress and compressive stress on ceramics at about corner of metal plate are occurred by the thermal cycles.

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Local large residual stress and local deformation appears clearly in area-array flip chip structures because of the difference in material properties such as Young's modulus and the coefficient of thermal expansion among a bump, underfill, and a silicon chip. Because such large residual stress and the local deformation deteriorate the reliability of electronic devices, they should be minimized for improving the reliability of products. In addition, the material properties of electroplated copper bumps were found to vary depending on their electroplating conditions and thermal history after the electroplating. Therefore, the authors measured the residual stress and the local deformation in a chip considering the influence of the material properties of electroplated copper bumps by using piezoresistive strain sensor chips. As a result, it was found that the amplitude of the local distribution of the residual stress reached about 100 MPa and the local deformation of about 650 nm remained on the back surface of mounted flip chip. It was also found that the local deformation decreased from 650 nm to 100 nm by annealing of copper bumps. Therefore, the mechanical properties of electroplated copper bumps influence the residual stress and the local deformation.

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The embedded strain gauges in a PQC-TEG were applied to the measurement of the change of the residual stress in a transistor structure with a 50-nm wide gate during thin film processing. The change of the residual stress was successfully monitored through the process such as the deposition and etching of thin films. In addition, the fluctuation of the process such as the intrinsic stress of thin films and the height and the width of the etched structures was also detected by the statistical analysis of the measured data. The sensitivity of the measurement was 1 MPa and it was validated that the amplitude of the fluctuation exceeded 100 MPa. This technique is also effective for detecting the spatial distribution of the stress in a wafer and its fluctuation among wafers. It was also confirmed that the final residual stress in a transistor is varied by the fluctuation of both the intrinsic stress in the deposited thin films and the cross-sectional structure of the patterned film. Therefore, it is very important to monitor the stress for assuring the reliability of the thin-film processing. Thus, this embedded strain-gauge technique is very effective for monitoring the fluctuation of the residual stress in a transistor in mass production.

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Electroplated copper thin films have started to be applied to not only interconnections in printed wiring boards, but also thin film interconnections and TSV in semiconductor devices because of its low electric resistivity. However, the electric resistivity of the electroplated copper thin films was found to vary drastically comparing with those of the conventional bulk material. This was because that the electroplated copper thin films consisted of a lot of porous grain boundaries. Thus, annealing is necessary for improving the crystallographic quality of the films. However, it was also observed that stress-induced migration occurred in the annealed film after the annealing. Large voids and hillocks grew during the custody of the film even at room temperature without any application of current. It was also found that sulfur atoms segregated in the grown hillocks, though no sulfur atoms were found by EDX in the initial as-electroplated films or other area in the annealed films. Thus, the hillock formation in the annealed films was enhanced by the segregation of sulfur atoms.

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Recently, indentation method has been developed to determine the elastic and plastic deformation properties of engineering materials. In this report, the elastic modulus of a composite material which is made of biodegradable polymer "Selgreen" and carbon fiber is determined by using the indentation method. In the method, obtained Young's modulus of a composite plastic depends on an indenter diameter, indentation depth and holding time at the peak load. Comparing the obtained results with the results by the compression test, it was found that these conditions should be selected to be 2.0mm, 0.5mm and 20s, respectively. Also, it is found that the indentation test is very useful and reliable in determining the elastic stiffness of a time dependent polymer composite.

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The elastic modulus of Zr based bulk metallic glass (BMG) after thermoplastic deformation was investigated. The Specimens of Zr55Cu30A110Ni5 BMG after thermoplastic deformation varying temperature and thermoplastic strain as parameters were carried out the uni-axial tensile test at room temperature. It is speculated that the elastic moduli of materials after thermoplastic deformation have large dispersion because of the volume fraction of the crystalline phase precipitating as the thermoplastic deformation.

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When an evaluation point shows plasticity, for instance, simplified elastic-plastic analysis can be applied in accordance with the JSME Design and Construction Code (Division 1, Light Water Reactor Code). However this method is known as conservative and elastic-plastic analysis with cyclic stress-strain relation should be performed to obtain an accurate fatigue usage factor. Therefore cyclic stress-strain relation has been developed for austenitic stainless steels. Cyclic stress-strain data were collected from several Japanese reports. Two types of relationship were employed. One is power law type and the other is Ramberg-Osgood type. Those relationships were converted to bilinear type relationships with considering appropriate margin.

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We study the load history effect on the plastic collapse load on the austenitic stainless steel piping subjected to combined tension and torsion. Three loading patterns considers as follows: a)Torsion load followed by tension load, b)Tension load followed by torsion load, c)Simultaneous load Tension and torsion load. The present paper describes a method for evaluating the collapse load from the tension stress ? displacement and shearing stress ? rotation charts. The plastic collapse load of the austenitic stainless steel piping follows von Mises yield surface regardless of load history.

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It is one of the difficult problems to predict the final shape of automobile parts. In order to solve the problems, the great demands to the finite element an analysis have been needed. Especially, it demands for an accurate analysis for the multi-stamping procedures have been increasing. The present research proposes the accurate constitutive models which can deal with the stress-strain responses (the Buschinger effect and the cross effect) du ring stress path changes. The calculated results are compared with the corresponding experimental results. From the comparisons, we can conclude the developed constitutive model is effective to increase the accuracy of sheet stamping finite element calculations.

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Recently, the eutectic solder alloys have been replaced by the lead-free solder alloys because of the environmental pollution problems. In this study, temperature and strain rate dependencies on plastic deformation behavior of both of Sn-37Pb and Sn-3.5Ag-0.75Cu solder alloys under biaxial loading with sudden change in strain rate after axial pre-straining at several temperatures are investigated experimentally and theoretically. The simulation analysis using newly developed constitutive model gives good predictions on plastic flow behavior of the both of Sn-37Pb and Sn-3.5Ag-0.75Cu solder alloys in loading along stress paths with a corner.

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