This study sought to fabricate a three-dimensional structure on a silicon surface using a combination of tribo-nanolithography (TNL) and wet chemical etching. TNL forms an amorphous phase on a single-crystal silicon surface that has an etch resistance against potassium hydroxide (KOH). A protruding structure can then fabricated with wet chemical etching. When the machined silicon is etched in hydrofluoric acid (HF), the amorphous silicon phase formed by the TNL is selectively etched whereas the non-machined silicon withstands the etching. The etch resistance of the TNL-induced amorphous phase can be controlled by the machining conditions, such as the normal load, overlap ratio, and number of times the area is machined. In this study, the resulting mechanism controlling the etch resistance was examined under different machining conditions. Changes in the etch resistance due to the normal load were caused by the thickness of the amorphous phase, while changes in the resistance due to the overlap ratio or number of times the area was machined were caused by the density of the amorphous phase.

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For a method for detecting the human body, such factors that no blind corner should exist, subjects other than human beings will not be erroneously detected. In this paper, a new method for detecting a human body wherein attention is focused on the human characteristics of walking will be studied. It had been known that a human body is electrified by walking, thus forming an electrical field around the human body. It was considered from walking waveforms in which human walking was reflected that a human body could be detected more advantageously. The measuring method is not affected by vibrations, etc. In addition, detection is possible with a simple electrode, which is advantageous in terms of cost. In this study, electrification on the human body in which components of actions of both feet are superimposed will be measured at a remote place, under an assumed living environment, and by using an algorithm that remotely detects walking characteristics based on the waveforms in which movements of both feet are reflected. Walking of 10 subjects including infants was actually measured, and a system, which is capable of detecting the number of steps at an accuracy of approximately 99.4% was shown.

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Hydrodynamic air film thrust bearings are widely used for very high speed, lightly loaded rotating machinery such as gas expander, compressor, gyroscope and business machines, etc. In the design of hydrodynamic air film thrust bearings, it is of cardinal importance to enhance the friction and stability capacities of air films for keeping the minimum friction loss within a particular level and for minimizing the vibration due to external excitations. Among various types of hydrodynamic air film thrust bearings, spiral and herring bone types of grooved bearings have an advantage of high stability and load carrying capacity, but the characteristics of the bearings depend on many design parameters. Therefore, when these parameters are designed suitably, it is expected to improve considerably the friction and stability characteristics of the bearings. In this paper, the optimum design methodology is presented to minimize the friction torque and also to maximize the stiffness of air film for spiral and herring bone types of grooved air film thrust bearings, and the applicability of the methodology is verified experimentally.

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In a manufacturing industry, establishment of the mass customization which is the management system that produces a product efficiently with diversification of a customer's request is pressing need. When the demand quantity is known, the new production plan system which performs mass customization had already been presented. In this paper, when the demand quantity is unknown, we proposed the model of mass customization about production and inventory planning. A new model is formulated as a linear programming problem based on a MIN-MAX strategy. This model can be used when demand quantity is not given. In this paper, we use the particle swarm optimization which is one of the methods of optimization problem in order to solve this model.

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The importance of precision grinding processes is continually increasing in a wide range of machine industry. In particular, the demands for cylindrical and internal grinding processes with higher accuracy and higher productivity than ever before have recently increased in the machine tool and automotive industries. Within grinding machine context, the conventional cylindrical and internal grinding machine of horizontal spindle type has been in the leading position. Nevertheless, such grinding machines of horizontal type have not necessarily the most suitable structure to achieve higher accuracy and higher productivity. In order to meet such industrial requirements, it is necessary to develop a machine tool based on a new design concept. However, only few studies on an innovative grinding machine have been performed so far. Therefore, in this study, a development methodology for machine tool is proposed to realize an innovative grinding machine. Then a vertical CNC multiple-function integrated grinding machine was developed by the proposed methodology. The results of actual machining tests confirmed that the grinding machine has a remarkable performance.

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We present a method of detecting production faults in flexible plastic packages using terahertz (THz) radiation. A focused THz beam is scanned along the sealed area of a package, and the transmitted signal is collected. Defect detection is effected through the large difference between the absorption coefficients of plastic and water for water-filled channel defects, and on the refraction index difference between plastic and air for air-filled channel defects owing to reduction of the incident signals into the detector. Compared to previous methods, such as visual and ultrasound inspection, our technique can be applied to optically opaque packages and does not require immersion in a matching liquid. The method was tested on fabricated 10∼100-μm diameter water-filled and air-filled channel defects imbedded in polyethylene films. The detection limit (the minimum size of a detectable defect), which depends on the conveying speed, was determined and analyzed. The results show that our system has potential for application in actual-production, real-time, inspection.

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In November 1999, the first vehicle with a traction drive CVT (continuously variable transmission) was manufactured and introduced to the market. The speed ratio changing mechanism of the half-toroidal CVT was theoretically analyzed by applying two equations of motion. However, neither analysis covers the effects of clearance and elastic deformation of the variator. Therefore, neither analysis can show correctly the behavior of the half-toroidal CVT during load transmission.
In this paper, we present a new analytical model for determining the elastic deformation and clearance of the half-toroidal CVT. We have implemented systematically our analytical model using MATLAB and Simulink. As a result, we can determine the behavior of the half-toroidal CVT during load transmission.

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This paper deals with the mechanism and relating matters on self-loosening rotation of bolted joints in the cases when very small slippages occur repeatedly at bearing surfaces under transverse loads. It can be supposed that accumulation of this kind of loosening finally produces serious states for bolted joints. Based on an assumption that a restoring force caused by an elastic torsion of a bolt shank which arises from a relative displacement between bolt and nut threads drives loosening rotation, a theoretical explanation is presented about how loosening rotation occurs and grows larger. Experiments in quasi-static states show results which agree with the theory of this paper. Additionally, consumption of transverse work and anti-loosening performance being taken up as relating subjects, more information about self-loosening is shown through examinations on some kinds of test samples.

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In case that a lot of products were cut out from a wide base sheet by laser cutting, the sheet had been much deformed so that the error occurred in a height regulator. This paper deals with thermal deformation of a base sheet caused by laser cutting. We clarified that the thermal deformation was influenced by the cutting sequence in the case of SUS304 sheets of 1 mm thickness. The workpieces bent upward in inward sequence, and the workpieces bent downward in outward sequence. It was expected that the deformation was able to be controlled by cutting sequence.

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In order to create a robotic tactile sensor of thin shape, a new optical tactile sensor is developed by applying a CT (Computer Tomography) algorithm. The present tactile sensor is comprised of infrared emitting diode arrays, receiving phototransistor arrays and a transparent acrylic plate and a black rubber sheet with projections. Infrared rays emitted from the diode array are directed into one end of the plate and their intensity distribution is measured by the phototransistor array mounted on the other end. If the CT algorithm is directly applied to the tactile sensor, there are two shortcomings: the shape of the sensing area is limited to a circular region and there is a long calculation time. Thus, a new CT algorithm oriented to tactile sensing is proposed for overcoming these problems. In the present algorithm, a square sensing area is divided into an N-by-N array and algebraic equations are derived from the relationship between the input and output light intensities on the assumed light projections. Several reconstruction methods are considered for obtaining pressure values caused in the squares. In the present study, the ART (Algebraic Reconstruction Technique) and LU decomposition methods were employed, and these methods were compared to select the best reconstruction method. In a series of simulations, it was found that the LU decomposition method held an advantage for the present type of tactile sensor because of its robustness against disturbance and short calculation time.

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Electro-rheological gel (ERG) is a new functional material whose surface friction and adhesive properties vary according to the intensity of the applied electric field. In a recent study, one-sided patterned electrodes were applied to the ERG and the change in surface frictional and adhesive property under the electric field, which is called the ERG effect, was experimentally confirmed. The ERG with one-sided patterned electrodes is considered to be suitable for application to a fixture device for micro milling. In this study, a prototype of the ERG fixture device was developed and its performance was experimentally investigated. The proposed ERG fixture devices can be useful for fixturing both metallic and nonmetallic workpieces, such as glass. Micro shrinkage of the ERG occurs in proportion to the voltage applied to the ERG material. Using this characteristic, the alignment of the workpiece can be also adjusted. The developed ERG fixture device was applied to the micro grooving process of a thin glass workpiece, and successful results were obtained.

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Production control such as the base stock policy, the kanban policy and the constant work-in-process policy in a serial production line has been studied by many researchers. Production lines, however, usually have fork-type, join-type or network-type figures. In addition, in most previous studies on production control, a finished product is required at the same time as arrival of demand at the system. Demand information is, however, informed before due date in practice. In this paper a join-type (assembly) production line under base stock control with advanced demand information in discrete time is analyzed. The recursive equations for the work-in-process are derived. The heuristic algorithm for finding appropriate base stock levels of all machines at short time is proposed and the effect of advanced demand information is examined by simulation with the proposed algorithm. It is shown that the inventory cost can decreases with little backlogs by using the appropriate amount of demand information and setting appropriate base stock levels.

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In conventional control systems in hard disk drives, it is difficult to compensate for disturbances above the primary mechanical resonance. In this paper, a design method that uses a virtual resonant mode in head-positioning systems of hard disk drives was developed. The virtual resonant mode is a digital filter that works like a mechanical resonant mode. Using the proposed method, stable resonant modes in a control system can be designed with a high degree of accuracy to compensate for disturbances whose frequencies are higher than that of the primary mechanical resonance. Application of this method to a hard disk drive showed that it significantly suppresses disturbances beyond the primary mechanical resonance.

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Deciding on buffer size for production lines has gained more and more importance because of growing complexity of the production lines and production costs. Many researches have developed numerous techniques for gaining the optimal buffer size which can aid in achieving maximum production rate. One of the search methods that can be used for studying buffer size in production lines is a genetic algorithm (GA). In this paper, we propose a production simulator (PS) to determine optimal or near optimal buffer size and, at the same time, to minimize the number of generations required to reach this optimal buffer size for the complex production systems (CPS). Our PS consists of a GA and a discrete event. For the most efficient use of the GA we introduce a new encoding method for GA called a Multi-Vector Encoding Method (MVEM).

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This paper deals with a method of scheduling manual work in consideration of learning by on-the-job training (OJT). In skilled work such as maintenance of trains and airplanes, workers must learn many tasks by OJT. While the work processing time of novice workers is longer than that of experts, the time will be reduced with repeated OJT. Therefore, OJT is important for maintaining the skill level and the long-term work efficiency of an organization. In order to devise a schedule considering OJT, the scheduler must incorporate a management function of workers to trace dynamically changing work experience. In this paper, after the relationship between scheduling problems and worker management problems is defined, a simulation method, in which a worker model and an agent-based mechanism are utilized, is proposed to derive the optimal OJT strategy toward high long-term performance. Finally, we present some case studies showing the effectiveness of OJT planning based on the simulation.

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