Articular cartilage of a knee joint is exposed to danger of wear after longer repeated movement. Mostly, elderly people suffered this kind of wear in their knee. Nowadays, wear caused by friction and abrasion is a common problem faced not only in engineering technology but also in human living body. However, in a way to solve the problem, a lot of study about lubrication mechanism is conducted but the researches are not entirely completed. In this study, We analyzed surfaces off the articular cartilage of pig's elbow and a knee using SEM and AFM.

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Model of proximal interphalangeal (PIP) joint is prepared and the stress state of PIP joint during hyperextension is analyzed by the finite element method. The concentrations of equivalent stress are found in the subchondral bone at the middle of articular surface, the volar plate near proximal phalanx and the attached portion of volar plate in the middle phalanx. The stress distributions of joints with same hyperextension angle are much alike, indicating that the distribution can be estimated by the hyperextension angle without knowing the conditions of applied load. The equivalent stress at the attached portion of volar plate in the middle phalanx is larger than that in the proximal phalanx, and the fracture is clinically observed in the middle phalanx.

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The purpose of this study is to investigate the influence of vitamin E (D, L-α-Tocopherol: VE) on microscopic deformation behaviour of UHMWPE. UHMWPE sample with 3wt% VE (3%VE) showed dispersed negative-strain area and also showed an elevation in Ic values indicating crystallinity after applying 30% tensile road. It is likely that molecular chains tend to reorient with deformation and the reorient sites tend to show the low area strain with the low Ic values. Considering that 3%VE had the negative area strain and the Ic values elevation, We hypothesized that the VE addition had the possibility to contribute to the molecular chains mobility and the reorientation which result in the increase of negative-strain area and the elevation of Ic values when tensile strain was applied.

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Contribution of α-tocopherol as an antioxidant to the improvement of long-term oxidation resistance of UHMWPE is an unknown mechanism. For γ-irradiated (25kGy), γ-irradiated (25kGy) with 0.3wt% α-tocopherol added, and γ-irradiated (25kGy) with 0.3wt% tocopheryl acetate added UHMWPE samples, oxidation index and crystallinity were calculated from infrared absorption spectra measured using Fourier transform infrared (FT-IR) microscopy. The oxidation index of γ-irradiated UHMWPE samples was extremely higher compared to those of doped ones. The crystallinity of γ-irradiated UHMWPE samples was lower compared to those of doped ones. Accelerated aging resulted in increases in crystallinity and oxidation index particularly in the undoped γ-irradiated samples. The incorporation of α-tocopherol significantly improves the long-term oxidation stability of γ-irradiated UHMWPE. Also, the addition of α-tocopherol controls macromolecular structures resulting in an increase in crystallinity.

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We propose that polyvinyl formal (PVF) be used for artificial articular cartilage in total joint replacement. The PVF is made from polyvinyl alcohol (PVA). Two types of PVF were provided to use tests. We estimated molecular structure of the PVF by FTIR analysis. A ball-on-plate reciprocating machine was used for investigation of the wear characteristic of PVF. The PVF plate was 3.0mm thick and stainless steel ball has a radius of 30mm. The constant load was 137N and average sliding speed was 20mm/sec. It proved that the difference of molecular structure, porous structure and its size of the PVF produce the variety of the wear characteristics. It is possible that we propose the proper cartilage for joint prosthesis, because the material properties of PVF can be modified in the manufacturing stage.

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The relationship between the dissolved oxygen in lubricating liquid and the tribological characteristic of a metal sliding on the same bearing material was investigated for design of metal-on-metal artificial hip joints. In a pin made from a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy sliding on the same material, a decrease in wear was often observed with the decrease in dissolved oxygen. This result cannot be explained by the traditional adhesion theory. It was demonstrated that the decreased wear with the decrease in oxygen was accompanied by a change of the hardness of the bearing material. We speculated that an increase in adhesion between the bearing surfaces resulted from the imperfect formation of the oxide film. This increase in adhesion affected the work hardening of the bearing material so that the wear resistance changed.

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The temperature of femoral head in artificial hip joints rose up more than 40℃ during walking. If the temperature of 40℃ or higher is maintained for a long time, it may become the cause of the increase of wear. The purpose of this study was to investigate the influence of the temperature of friction part in femoral head on wear characteristics and wear debris in artificial hip joints. The temperature of friction part was adjusted at 30, 36, 40 and 42℃ with a temperature controller. Lubricating liquids used a phosphate buffered saline (PBS) and the PBS that contained the principal constituents of synovial fluid. Wear depth increased with the increase of the temperature of friction part. There were no significant differences in the wear debris between temperatures of 30 and 42℃.

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The pourpose of this study is to investigate the relation between electric property and mechanical property for articular cartilage. Collagenase and hyaluronidase were used to degrade the collagen fibril and proteoglycan respectivily. Electric impedance mesurement, visco-elasticity measurement and indentation test were carried out to evaluate the electric and the mechanical property for articular cartilage before and after enzymatic treatment.

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Total hip arthroplasty (THA) is mainly used for the patients, who are affected with rheumatoid arthritis, coxarthrosis, and so on. The long-term success of total hip arthroplasty depends on the chance of acrylic cement failure and interface disruption. The purpose of this study is to minimize the risks of cement failure by using optimization. A generic three-dimensional FEM model of the proximal femur containing a cemented femoral stem of a total hip arthroplasty was developed. The design parameters are defined on cross section of stem. The design objective was to minimize several principal stresses in the cement mantle from several load conditions. In optimization, multiobjective generic algorithm (MOGA) was used to remove the extreme value.

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Effect of the surface topography on the adhesion of the artificial joint was evaluated in vitro. Alumina plates with beads and honeycomb structural surface were prepared as specimen. Bone marrow-derived mesenchymal stem cells were seeded on the surface of the bone plate and the alumina plates. After cultivation, the shear test was carried out to mesure the adhesive strength between the bone plate and the alumina plates. Quantitative mesurment of alkaline phosphatase activity, DNA and Ca amount were measured quantitatively and the surface of the alumina plate was observed by scanning electron microscope. The result showed that the surface topography affected activity of osteoblast and adhesion of the artificial joint.

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The dynamic mechanical loading are known to stimulate extracellular matrix synthesis of cultured chondrocytes. In this study, we developed the culture system that simulated biaxial dynamic loading applied articular cartilage in vivo. We investigated the influence of dynamic compressive loading on mechanical properties of chondrocyte-agarose construct. After 1day in static culture, constructs were exposed to cyclic uniaxial compressive strain (15%, 1Hz, 6h/day) for 7days and 14days. Then, tangent and equilibrium moduli of the specimen were obtained by unconfined compression test. The results show that the tangent modulus of compressed samples is significantly higher than control. CLSM images suggested that regeneration of collagen typeII tissue structure was stimulated under dynamic loading.

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Recently the demand of the Wheelchair Transfer Vehicles (WCTV) which transport elderly and disabled persons sitting in their wheelchair is increasing rapidly. Accordingly the number of accidents during transportation of people is also escalating. This study researched WCTV service providers who had encountered "Hiyari・Hatto" (HH) while they drive the WCTV. Done on the questionnaire survey to the WCTV service providers and got 123 responses (41.0% response rate). The findings were as follows: (1) Fifty-four people among 112(48.2%) were experienced of HH on WCTV. (2) There is no significant between the age of the cars and HH (3) HH was few in four point fixation of the W/C, on the contrary, two point of fixation of the W/C was many HH. (P<.05). (4) The Situations of HH on WCTV were the posture collapse and the bad road state so far. It was suggested that the way of fixation of the W/C is the most important for the safety transportation on WCTV.

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A lot of handicapped people feel endangered when they move somewhere on the vehicle with them sitting on the wheelchair. But there is no restriction for the people sitting on the in-vehicle wheelchair during vehicle driving. So this paper deals with a human body response and in-vehicle wheelchair during vehicle travel. Wheelchair is fixed on the carriage with four-point fixing means and response of human on the wheelchair in crash stop is measured. ;muscle activity of stemocleidomastoid, splenius capitis, rectus abdominis and latissimus dorsi, displacement of angle of neck and lumbar part, acceleration of head and breast. Moreover we did mathematical simulation of the human response and compared experiment conclusion to simulation.

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It is often difficult for handicapped people using the electric wheelchairs to maintain their posture against external forces. Therefore, it is important to reduce the instability in driving the wheelchair under the various road conditions. In this study, the active level holding seat mechanism available for the general electric wheelchairs is proposed. In order to reduce the increase of seat height, optimal link parameters were designed to minimize the size of linkage. A prototype model of level holding mechanism was made practically. The effect of the proposed mechanism was evaluated by the running tests with electric wheelchair. As the results, the stability of the driver and wheelchair system increase by the decrease of the upper trunk displacement of driver using this seat mechanism.

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A toromi meter (a hand-held viscometer) was developed for the care support of swallowing disorder. The toromi meter developed made easy operation possible on cooking. The cone was detachable easily, and was washed after measurement. The meter was applied to some liquid foods. The practical applications to the care support were discussed.

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One of our authors has articulation handicap and feels strongly the importance of the voice information in conversation that cannot be expressed with texts. We are considering about a system which makes the indistinct sound clear and which keeps the speaker's feature of voice as much as possible. We examined some methods. In the experiment using single Mora, by adding clear consonant waveform to the indistinct sound, unvoiced consonant and some voiced consonant have been made clear. Moreover, the vowel has also been made clear using wavelet transform ation. Also, we used the wavelet transformation for speech recognition, and it modestly recognized some indistinct sound.

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Because the giraffe has a very long neck, it is a extremely interesting phenomenon how giraffe breathes. This research develops the non-contact measurement system to measure the aspiration parameters of giraffe. Because giraffe is so nervous that even a little contact makes him breathes unnaturally. In order to know aspiration of mammal, in this study, an attempt is made to measure the moving of the body surface using the stereo camera. To evaluate this method, firstly, we measured the human aspiration. The 3-d coordinates of the feature points on the body show the aspiration cycle characteristically. The aspiration volume is noisy, and we need to improve the method of measurement and analysis.

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The report describes a microwave prospect system of plant vermin living in the soil. The system serves to detect the vermin without digging up the soil. However, there are some problems to detect it using the microwave sensor because the microwave signal rapidly attenuates on traveling in the soil with rich moisture content. The experiment was performed to detect the movement of a scarab beetle larva with 15mm length and a speaker (diameter 5mm). The limitations of detection were investigated to the movement of the beetle and vibration of the speaker berried in the soil. Limitations of detection to the former and latter were 3cm and 4.5cm, respectively.

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The tree has the abilities of both the self-optimization and the self-restoration by changing to adapt each part of stem and root, opposing power to receive from nature. Present study investigates structural morphology and suspension mechanism of root and stem to zelkova and Pinus Thunbergii applied gravity and wind load to stem using two dimensional large deformation finite element analyses. It revealed that both zelkova and Pinus Thunbergii well utilize physical properties of soil and increase the holding power of soil by spreading their roots for appropriate direction.

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A cell rotation system (CRS) has been developed to observe three dimensional (3D) morphology of cells precisely from their images obtained from various points of view. In this system, cell held with a micropipette under a microscope is rotated around the axis of the micropipette set perpendicular to the optical axis, while the pipette tip is kept in position based on the binarized image of the pipette tip. The displacement range of the pipette tip was narrow in the previous system. In this study, a lever mechanism was introduced to widen the displacement range. We also introduced a flexible cell access mechanism capable of holding an arbitrary cell on a slide glass. In addition, we have succeeded in the real-time pipette tip position control by using feedback control in combination with feedforward control.

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The purpose of this study is to investigate the signal transduction process for the environment response. It has been shown by various researches that the supernatant as conditioned medium have various growth factor and effective substance for the cell adhesion and inducer for cell differentiations. In this study, we focused attention on the conditioned medium of low-temperature and high-pressure environment. The change in viability of cells under low-temperature and/or high-pressure condition derived supernatant was evaluated. The high-pressure condition was set by hydrostatic-pressure apparatus using controlled piston mechanism. The results suggested the presence of some environment-derived communicative matter, but not yet have proved.

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The stress relaxation test was performed for cultured rat aortic smooth muscle cells using a laboratory made micro tensile tester with feed-back control. Untreated cultured cells and cells treated with cytochalasin D to disrupt their actin filaments were stretched by 70-85%, and their length was kept constant to obtain stress relaxation curve. Viscoelastic analysis with a standard linear solid showed that viscoelastic parameters of the cells did not change in response to actin filament disruption. Fluctuation in tension was observed in the stress relaxation curve of the untreated cells. Such fluctuation disappeared in cells treated with cytochalasin D. The fluctuation in tension may be caused by dynamic change of intracellular actin filament organization.

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Endothelial cells are known to change their shapes aligned perpendicular to the direction of cyclic stretch. However, the mechanisms are still not clear. In this study, we developed a new cell-stretching device which allows continuous observation of cyclically stretched/relaxed cells. By using this apparatus, morphological changes of single cells in response to cyclic stretch (1Hz, 10%, 2 hours) were visualized and analyzed. The data showed that there were two major patterns of morphological changes of ECs, depending on their initial shapes. While ECs with round shapes at initial state changed their shapes to become more elongated in a direction perpendicular to the stretch, cells oriented and elongated in the stretch direction at initial state changed their shapes to become rounder first and then to become elongated perpendicular to the stretch direction. In addition, this cyclic-stretch-induced endothelial morphological change was blocked by Y-27632, a Rho-related kinase inhibitor, or blebbistatin, a myosin inhibitor. Taken together, cell retraction as well as elongation is important in the stretch-induced endothelial morphological changes, and this contraction may be induced by stress fiber contraction via ROCK-mediated myosin phosphorylation.

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In this paper, to investigate the effects of shock waves on the endothelial cells in vitro, the cells by plane shock waves are observed by microscope and the growth rate and others are measured by image processing. The peak pressure worked on the endothelial cells in water at the test case is 0.4MPa. After working shock waves on suspended cells and fixed cells, the disintegration, shape and growth are investigated. It is shown that the growth rate of suspended endothelial cells are accelerated by plane shock waves and the dividing time for cells in case of layered cells are changed by shock wave.

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In recent years, the tendencies to use computer simulations as tools for a medical treatment and diagnosis have been growing. In each human-body, there is a complex relation between blood flow and the blood vessel wall, which is slightly different for each individual. Thus the entire simulation, especially grid generation, needs a lot of time and advanced knowledge. Therefore, we have difficulty to use the simulation for real-time medical tool. As tool capable of reducing the time and the trouble required for making a grid, we have developed blood flow and blood vessel interaction simulation system, which directly uses images from medical diagnosis instruments for constructing a computational grid. In this paper, we present an outline of the system, some ideas, and give some examples the behavior of blood flow and blood vessel interaction.

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We investigated the effect of changes in micro-structural components on the macroscopic level of mechanical behavior in porcine thoracic aorta. We carried out uniaxial stretching test and histological observation for vascular segments which were subjected to freezing and thawing. We chose five conditions of freezing and thawing, applying each condition to two aortas. From each aorta we took 3 specimens for the mechanical test and 1 for histological observation. The results show the tissue stiffening by freezing and thawing and no correlation between the stiffening and micro-structural changes. These findings may suggest the stiffening of fibrous components such as elastin and collagen.

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Human's Ascending Aorta have torsion. It is known Aneurysm patient's torsion of Ascending Aorta is generally larger than healthy person's one. We made some kinds of Aortic Arch models have torsion, and calculated blood flow in aorta. We researched how the size of torsion affected blood flow and wall-shear stress. The location of Arteriosclerotic Disease was compared with points blood flow and wall-shear stress were changed. As a result, we obtain tendancy of distribution of wall-shear stress by the torsion.

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When the blood flow is analyzed numerically, the blood vessel is generally modeled with an elastic body or a comparatively simple viscoelastic model. Recently the computational method which takes a more complex generalized viscoelastic model has been developed as one of the methods of doing the numerical analysis of the cardiovascular system. As a result, it is understood that the viscoelasticity is a matter that cannot be disregarded as a characteristic of the blood vessel. However, only when pressure is assumed as much lower than human blood pressure, the numeric calculation is effective. Therefore, in this study, viscoelasticity property of a silicon tube, which is a polymer and has similar characteristics to the blood vessel, has been examined when a high pressure is applied to the tube.

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In the Paper handling machine such as ATM, a well-known method of separating paper sheets is to arrange a feed roller nested inside a gate roller. This method is made sensitive to the thickness of paper sheets to prevent overlapped paper sheets from passing between the rollers. However, this requires repeated fine-tuning to adjust the depth of the nest. This paper presents a means of improving the effectiveness of the separating system

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A web is a continuous, flexible materials such as paper, plastic film, metal foil, textiles etc. Web wrinkling is a problem which plagues the web process industries. Most webs are very thin and prone to buckle or wrinkle. The effects of wrinkling can range from compromised product quality to down time of a processing operation, leading to less profitability in the manufacturing operation. The web wrinkles which will be treated in this paper are those that can be affected by roller misalignment and friction characteristics between web and roller. In this first report, Observation method is presented for paper-web wrinkling.

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A web is a continuous, flexible materials such as paper, plastic film, metal foil, textiles etc. Web wrinkling is a problem which plagues the web process industries. Most webs are very thin and prone to buckle or wrinkle. The effects of wrinkling can range from compromised product quality to down time of a processing operation, leading to less profitability in the manufacturing operation. The web wrinkles which will be treated in this paper are those that can be affected by roller misalignment and friction characteristics between web and roller. It is shown how web wrinkles can be predicted and ultimately avoided in manufacturing operations. In this second report prediction method is presented with experimental verifications.

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In the web handling systems, before being converted to the final product, the web undergoes several processes, for example, transportation by the drag roller, press, printing, coating, drying, slittering, winding, and so on. Under such processes, the web is given the additional values to enhance the quality and function of product. However, when the web defect are generated in the handling processes, the defect immediately result in quality loss. Therefore, to predict and protect the defect is very important engineering problems cannot be seen in the literature. In this paper, the idea of web defect map for predicting the web defects such as wrinkling, slipping and lateral motion of web is presented.

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Some of congenital blind persons recognize obstacles and surrounding environment by sounds. This ability is called obstacle sense. But it is relatively difficult for the blind who lost their sight posteriori to acquire this ability because they don't have long acoustic training. This research intended them and examined the sounds which are easy to recognize obstacles. We carried out the experiment of pointing to the opened direction with white cane or synthetic sound on some sighted people wearing an eye mask. We found accuracy of the angle of pointing to the opened direction and the time from starting to sound. Additionally we carried out the experiment of walking against a wall with white cane or synthetic sound on some sighted people. Then we measured the distance they felt to be or run into something while walking. Finally, we found the relationship between these sounds and easiness to recognized obstacles.

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In this study, a mobile Health Monitoring System (HMS) for the diabetes patient is newly developed. Main subjects of this HMS design are (1) a painless microneedle with inner diameter less than 100μm, (2) the vacuum blood extraction of 1μl, and (3) measurement of blood sugar level by using MOS-FET and Glucose sensor. The vacuum blood extraction system with a microneedle and blood sugar sensor is set in a disposable disc cartridge. Simultaneously, the mechanism of vacuum blood extraction was analyzed, the blood flow rate was measured, and the performance of blood sugar sensor was evaluated. Finally, this HMS succeeded in extracting 3μl of human blood within 0.3 sec and measuring the blood sugar level by the automatic operation.

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The purpose of this research project is to develop a compact and wearable human blood extraction and drug delivery system applying to analyze a blood sugar level as a health monitoring system (HMS), which is called "Mobile Hospital", without a centrifugal separator and a large scale blood sampling system such as conventional glucose level monitors. The design concept is Bio-MEMS from the female mosquito's blood suction mechanism. We will apply the developed device to the wristwatch type HMS. It consists of (1) a painless microneedle, (2) an indentation unit using a shape memory alloy (SMA) actuator, (3) a micropump for human blood extraction using a piezoelectric microactuator, (4) a bio-sensor to detect and evaluate the amount of Glucose in extracted blood using an enzyme such as Glucose oxidase, and (5) an micropump for insulin dosage. In this paper, we have especially reported design, production and performance of the above (3) to (5).

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To tailor the characteristics of molecularly thin lubricant films, magnetic disk surfaces coated with nanometer-thick perfluoropolyether AM3001 lubricant films were irradiated with 172nm ultraviolet (UV) rays through a photo mask in nitrogen atmosphere. By measuring the time-dependent thickness profiles, we found that lubricant molecules in the non-UV-irradiated area spread toward the UV-irradiated area until the re-distributed lubricant thickness reaches an equilibrium state. We also confirmed that three-dimensional lubricant textures can be formed on magnetic disk surfaces utilizing the UV-induced film re-distribution phenomenon.

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The thickness dependency of damping coefficients and spring constants of liquid bridges of PFPE lubricant were measured by means of regression analysis of damping vibration of the liquid bridge which were formed between a diamond tip and the surface of a magnetic disk. Two type of PFPE lubricants having different molecular weight (Zdol2000 and Zdol4000) with the thicknesses of roughly 8nm, 20nm, and 40nm, were coated on the DLC surface. The damping values expressed and the spring constants had U-shaped profile along with the bridge elongation as reported in the previous study. In the thinner film (8nm), it was confirmed that the both values had no increase after the minimum value (L-shaped profile), and the damping value and the absolute of spring constant were a few times as large as those of the thicker films.

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The lubricant thickness and retractive velocity dependency of the adhesion force between the diamond tip and the disk surface were measured while the tip was withdrawn from the disk surface with PFPE lubricant film. The dynamic adhesion force model was also adopted to analyze the transient vibration of the cantilever after the tip was separated from the disk surface. This method clearly visualized the non-linear phenomena occurred at the initial separation, the rupture of the liquid bridge, and also the minute fluctuation in the inclination of the adhesion decreasing profile. The PFPE lubricant having functional end groups (Zdol2000) with the thicknesses of 29nm and 63nm and the retractive velocities of 29, 57, 111, 219μm/s were employed to measure the lubricant thickness and velocity dependencies. The contact force which occurred at the separation between the diamond tip and the disk surface was maximum value in the adhesion profile and largely attributable to the lubricant thickness and slightly to the retractive velocity.

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Gas temperatures of nano-meter flying sliders are calculated using DSMC; Direct Simulation Monte-Carlo, method. An inverse step slider is used to investigate the gas temperature drops at the step position of the sliders. The DSMC calculation was done with two boundary conditions of the slider; wall running velocity and inlet pressure. The results show that gas temperature drop at the step position depends on the gas flow velocitiy at the position.

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Vibration transfer characteristics through a liquid meniscus bridge were investigated experimentally using the meniscus response apparatus. Effects of the excitation amplitude and the contact angle on the vibration transfer characteristics were clarified. The large contact angle was obtained by applying oil repellent to a glass plate. As the results of examining effects of the contact angle, it is thought that the spring constant of menisucs is positive though the contact angle was smaller than 90 degrees.

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To examine behaviors and stabilities of ultra-thin but continuum liquid films, the long wave theory was employed, which is the time-evolution equation for the shape of the thin liquid film and includes surface tensions and surface forces such as the van der Waals (vdW) forces. For lubricants with chain-end functional groups such as Z dol, surface forces acting at the liquid surface depend on the liquid thickness, and the direction of the force changes alternatively with the thickness. In this report stability/instability and time-evolution of the polar lubricant surfaces was numerically analyzed and steady liquid film configurations were obtained.

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A highly precise tracking actuator for a magnetic recording evalution system was developed. The tracking actuator called the Nano-motion actuator(NMA) was consisted of a displacement amplitude mechanism and a layered piezoelectric element (PZT). When the actuator is load on a track with HGA, a attachment is inserted between the NMA and the HGA. The attachment is a large mass of 15g for the NMA. In this paper, we tried wide servo bandwidth with the large mass and the sub-nano meter positioning could be measurement system for precise positioning realized.

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It is important to clarify air flow induced vibration issues for hard disk drives in order to achieve ultra-high magnetic recording density. We studied flow induced flutter vibration in actual 2.5 inch HDD which has one disk and two magnetic heads. In this study, the disk flutter vibration as well as static pressure distribution between the top cover and disk were measured, changing the magnetic head slider track following modes as well as the seek modes. From these experimental results, it was found that the disk flutter amplitude increases and its frequency decreases, when the magnetic head is operating on a disk. We also found that the mean pressure distribution was changed under various head operating conditions. As a result, it suggests that a disk flutter amplitude increase is due to the change of mean pressure distributions and disk flutter frequency decrease is caused by the effect of head-disk coupling vibration system.

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The reduction of windage, flow induced vibrations of head sliders in the off track direction, is an important step towards increasing the track density of hard disk drives. We measured windage of several types of head gimbal assemblies in the various conditions such as disk rotational speed and atmosphere temperature by using laser-doppler-vibrometers, particle-image-velocimetry, laser-doppler-anemometers, and custom-made spin-stands. We discovered windage can be reduced by decoupling the vibration modes and increasing the resonance frequencies of head gimbal assemblies.

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In order to study aerodynamic characteristics of a carriage arm equipped on hard magnetic disks, water tunnel tests with 10 times enlarged model of an actual carriage arm were conducted under Reynolds number similitude, which allows the time scale of the tests to expand approximately 1300 times larger than that under actual condition in the air. In the tests, flow visualization around the carriage arm model with fluorescent dye injection and Laser-light sheet technique was carried out. Fluid dynamic drag, lift and torque on the model were also measured. Effects of incident flow velocity and incident flow angle were investigated.

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Today's head/disk interface design has a wide flying height distribution due to manufacturing tolerances, environmental variations, and write-induced thermal protrusion. To reduce the magnetic spacing loss due to these effects, we have developed an active head slider with nano-thermal actuator. The magnetic spacing of these sliders can be controlled in-situ during operation of the drive. After simulating the heat transfer in the slider and resulting thermal deformation of the air-bearing surface, we fabricated a thermal actuator by thin film processing. The evaluation by a read/write tester showed a linear reduction in magnetic height as electric power was applied to the actuator. The actuator's stroke was 2.5nm per 50mW with time constant of 1 msec. We found no significant impact to the reliability of the read element.

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In order to realize ultra-low flying heights, magnetic spacing variations due to manufacturing tolerances, environmental variations, and write-induced thermal protrusion need to be reduced. To decrease the flying height, we have developed a thermal flying-height control (TFC) slider that carries a micro-thermal actuator. Using the device, the magnetic spacing of these sliders can be controlled in-situ during operation of the drive. First prototype had shown insufficient characteristics when evaluated at a component-level prototype. Therefore, the purpose of this research is to verify drive-level feasibility and better actuator characteristics. After analytical design by simulation of heat transfer and thermal deformation, second type of TFC device was fabricated. Component level evaluation showed sufficient actuator characteristics that met the requirements leading to the development of drives with controllable flying-height sliders. Drive level evaluation showed its effectiveness in reducing the magnetic spacing.

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Recent flying heights of magnetic head slider have been reduced to 10nm or less. Thermal pole-tip protrusion can further reduce flying clearance by a few nanometers and increase the risk of failure at the head-disk interface. The safety margin of the flying height decreases due to thermal pole-tip protrusion deformation. This deformation is caused both by mismatched thermal properties of the various materials used in the magnetic head and the temperature rise due to write current in the coil. We clearly identified the mechanism of this protrusion and accurately estimated its magnitude. In this study, we numerically analyzed the thermal pole-tip protrusion of magnetic head using low thermal expansion material. And our calculations showed that this magnetic head structure effectively controlled the thermal pole-tip protrusion.

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The purpose of this study is to examine whether we can estimate the human postural control ability while standing. The human body is modeled as a two link inverted pendulum composed of the ankle and hip joint, and the viscoelastic parameters at the leg joint act in order to hold standing. We assumed that calculating the viscoelastic parameters was useful to assess the ability of human postural control. Three male volunteer participated in the experiment for calculation of the viscoelastic parameters. The angle, angular velocity, and angular acceleration at the ankle and the hip joint were obtained when the external force was exerted, the viscoelastic parameters were calculated from the equation of motion of the model. Some of the obtained viscoelastic parameters helped the postural control of the simulated movement, but it is suggested that we need further consideration for the validity to estimate the the human postural control ability.

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