Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-an-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is I325W of the laser power, and I.4m/min of laser welding speed.

The method for fatigue life prediction of ball bearing is proposed applying the algorithm of contact fatigue prediction based on stress analysis. In order to do this, a series of simulation such as initial surface stress analysis, EHL analysis, subsurface stress analysis and fatigue analysis are conducted from the loading at each ball location calculated for a bearing subjected to external bearing load and contact shape function. And uniaxial fatigue tests are performed to obtain fatigue parameter of AISI 52100 steel. It was found that since stress is usual1y higher at the inner raceway contact than at the outer raceway contact, fatigue failure occurs on the inner raceway first. When the fatigue life calculated in the stress-based method are compared with LSO life ofL-P model, Cross land criterion for the radial load increment is similar to LSD life and Dang Van criterion for the axial load increment is similar. In the case of EHL contact, there is no difference of fatigue life between dry contact and EHL contact, when maximum Hertz pressure exceeds 2.5GPa.

In the braking of railway rolling stock, the slip that is the relative velocity between train body and its wheel affects the adhesive force which is connected to the braking force. The coefficient of the adhesive force changes in accordance with the slip and the condition of a rail road. Namely, its value increases upon the maximum on a rail condition, and there it declines conversely while the magnitude of slip keeps rising on. First, this paper introduced a reference slip generator so that can utilize maximum adhesive forces with a disturbance observer for estimating unmeasurable current adhesive forces which is as an input of the generator. And, an adaptive sliding-mode control system has been synthesized for minimizing the error between reference and current slip. Finally the effectiveness of the proposed control system is evaluated by computer simulation.

A simple dimension measuring method for the measurement of human bust has been developed using projection moire. The 3-D data of a human bust was calculated from the 2dimensional image information obtained. by the stripe using projection moire. The creation of 3-D geometric shape by digitizing real objects has been widely investigated in reverse engineering(RE). This procedure generally consists of three basic steps: data capture, data alignment and model reconstruction. In order to achieve a complete model, multiple scans must be taken and aligned.

It is strongly requested to reduce fuel consumption because of high oil price and exhaust gases of road vehicles for environmental preservation. To solve these problems, several types of hybrid vehicles have been developed. Among them, flywheel hybrid vehicle using variable displacement pump/motor was already proposed as one of the feasible hybrid systems in place of hybrid vehicle by the conventional storage battery. The proposed flywheel hybrid vehicle is to keep constant pressure of high pressure line by the control of swash plate angle of flywheel pump/motor as pressure compensator. The efficiency of the overall system depends severely on the efficiency of hydraulic pump/motor in the energy saving hydraulic control system by simulation. According to the control methods of swash plate angle of piston pump/motor, there remain several problems to be solved.
In this paper, experimental setup for energy saving is fabricated and the efficiency of energy saving is investigated by experiments with respect to various experimental conditions.

CA TIA VS is one of the most preferred softwares in product design for domestic and industrial use. But with the development of the IT industry, design data by CATIA VS can easily be hacked and stolen especially via the internet and through assistance storage medium. The design data could be protected through executive, physical and technical security system. the best way to maintain confidentiality of data from unauthorized access is to have a cryptosystem of the technical security. In this paper, a cryptosystem for the protection of design data was being proposed.
The memory contains the file information made by the New and Open function of CATIA VS. No error can be expected even if the file changed before of after the application of Save and Open function. A cryptosystem was constructed in CATIA VS by inserting crypto algorithm before and after the I/O process. The encryption/decryption algorithm of each function was based on the complex cipher, which applied permutation cipher and transpose cipher. The file security system was programmed in CAA VS and Visual C++.

This work is to fabricate a precise optical fiber array using polymer composite for optical interconnection. Optical fiber array has to satisfy low optical loss requirement less than 0.4 dB according to temperature change. For this purpose, design criteria for an optical fiber array was derived. The coefficient of thermal expansion of silica particulate epoxy composites was affected by volume fraction of silica particles. And also, elastic modulus of silica particulate epoxy composites was affected by volume fraction of silica particles. To obtain the coefficients of thermal expansion below 10 x IOE?6f"C and elastic modulus more than 20 GPa, we chose the volume fraction more than 76%.
Using silica particulate epoxy composites with the volume fraction 76%, 8-channel optical fiber array with dimensional tolerances below I tL1ll was manufactured by transfer molding technique using dies with the uniquely￢designed core pin and precisely-machined zirconia ceramic V block. These optical fiber arrays showed optical loss variations within 0.4 dB under thermal cycling test and high temperature test.

Inkjet printing has become one of the most attractive manufacturing techniques in industry. Especially inkjet printing technology will soon be part of the PCB (Printed Circuit Board) fabrication processes. Traditional printing on PCB includes screen printing and photolithography. These technologies involve high costs, time-consuming procedures and several process steps. However, by inkjet technology manufacturing time and production costs can be reduced, and procedures can be more efficient. PCB manufacturers therefore willingly accept this inkjet technology to the PCB industry, and are quickly shifting from conventional to inkjet printing. To produce the printed circuit board by the inkjet technology, it must be harmonized with conductive nano ink, printing process, system, and inkjet printhead. In this study, micro patterning of conductive line has been investigated using the piezoelectric printhead driven by a bipolar voltage signal is used to dispense 20-40 urn diameter droplets and silver nano ink which consists of 1 to 50 nm silver particles that are homogeneously suspended in an organic carrier. To fabricate a conductive line used in PCB with high precision, a printed line width was calculated and compared with printing results.

A novel selective metallization process to fabricate the fine conductive line based on inkjet printing has been investigated. Recently, Inkjet printing has been widely used in flat panel display, electronic circuits, biochips and bioMEMS because direct inkjet printing is an alternative and cost-effective technology for patterning and fabricating objects directly from design without masks. The photosensitive etching resist used in this process is an organic polymer which becomes solidified when exposed to ultraviolet lights and has high viscosity at ambient temperature. A piezoelectric-driven ink jet printhead is used to dispense 20-30 pm diameter droplets onto the copper substrate to prevent subsequent etching. Repeatability of circuitry fabrication is closely related to the formation of steady droplets, adhesion between etching resist and copper substrate. Therefore, the ability to form small and stable droplets and surface topography of the copper surface and chemical attack must be taken into consideration for fine and precise patterns. In this study, factors affecting the pattern formation such as adhesion strength, etching mechanism, UV curing have been investigated. As a result, microscale copper patterns with tens of urn high have been fabricated.

Photochemical patterning of self-assembled mono layers (SAMs) has been performed by diode pumped solid state (DPSS) 3rd harmonic Nd:YV04 laser with wavelength of 355 nm. SAMs patternings of parallel lines have subsequently been used either to generate compositional chemical patterns or fabricate microstructures by a wet etching. This paper describes a selective etching process with patterned SAMs of alkanetiolate molecules on the surface of gold. SAMs formed by the adsorption ofalkanethiols onto gold substrate employs as very thin photoresists. In this paper, the influence of the interaction between the functional group of SAMs and the etching solution is studied with optimal laser irradiation conditions. The results show that hydrophobic functional groups of SAMs are more effective for selective chemical etching than the hydrophilic ones.

According to the pedestrian protection regulations of Europe and Japan, the head injury must not exceed a limitation in the defined test condition for the protection of pedestrians from a vehicle crash. However, it is difficult to evaluate the performance of protection because each regulation has different test conditions such as dummy, impact speed and so on. This circumstance needs the development of a model that describes the anthropometry of the crash victim with a sufficient accuracy. We constructed scaled pedestrian dummies using MADYSCALE. Simulations were performed for various crash speeds and pedestrian postures. The scaled Korean dummies and Hybridlll dummies were used to compare the pedestrian dynamic behaviors and head injury criteria during the collision. The HIC values of scaled korean dummies were found to be higher than those of Hybrid HI dummies. The impact for gait posture was less than that for standing.

A finite element simulation model was developed for the performance optimization of a closed type air-cell mattress used for the ulcer prevention. An H-model with material properties of human flesh and kinematic joints were used for the calculation of the body contact pressure. The material property of rubber air-cell was evaluated by tensile test of standard specimen. We evaluated the body contact pressure distribution after laying human model on the inflated air-cell mattress. It was found that the body contact pressure was dependent on cell height, but hardly affected by the thickness of the rubber in a cell.