• Journal of the Korean Society of Costume
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• v.25
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• pp.21-39
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• 1995

By 1980, there are two main flows in the world fashion. One is the traditional Paris fashion by Houte Couture, and the other is the American casual fashion by mass production. However, the appearance of Japanese designers and their new styles on the stage of Paris fashion have had a strong influence on the change of the world fashion since 1980s. So, the purposes of this study were first to research the process, the background and the power which let the Japanese stand and suc-ceed in the stage of Paris fashion, second to research on the Fashion World and Fashion Trend from the beginning of 1980s to present (1994). The results were as follow ; Hanae Mori and Kenzo were the pioneers who let the West know the existence and the level of Japanese fashion. Issey Miyake was the new innovator in the 20th century Fashion. and became the foundation of the New Wave Fashion in 1980s. Rei kawakubo completed the philosophy of beauty by the imperfection and has led the Postmodernism in the Fashion. The constant efforts of the these Japanese designers have inspired the orientalism and Art-to Wear, showed up the new construction and material in clothing by layering and drap-ing and stimulated the traditional Paris fashion to become popular, casual and diverse. The success of Japanese designers and the boom of Japanese fashion were not only the effort of individuality but also the power of economics, the spirit of cooperation and the affection to the culture and tradition on the background. The New Wave fashion by Japanese designers in the beginning of 1980s have promoted the appearance of Avant-garde fashion in London, the new fashion spirit in Milano, and the various fashion styles of different sections in the West and East. Finally, it becomes popular in 1990s and leads the fashion spirit in the end of 20th century.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.785-791
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• 2000

GDI (Gasoline Direct Injection) engines are considered as one of the candidates for next generation engines of passenger cars, which reduce exhaust emissions and fuel consumption. In GOI engines, a high-pressure gasoline supply system is required to directly inject the fuel to combustion chambers. Because of low lubricity of gasoline fuel, the clearance between a plunger and a barrel in GDI fuel pumps is too wide to achieve smooth hydrodynamic lubrication. Thus, it is difficult to generate high-pressure condition in GDI fuel pump since large amount of leakage flow occurs between the plunger and the barrel In this study, an optimum plunger design is presented to minimize leakage in the aspect of flow control. This paper analyzes leakage flow characteristics in the clearance to improve pumping performance of GDI fuel pumps. Effects of groove in the plunger are studied according to variations of depth and width. Evaluations of pumping performance are determined by the amount of pressure drop in the leakage path assuming a constant leakage flows. Both of turbulence and incompressible models are introduced in CFD (Computational Fluid Dynamics) analysis. Design parameters have been introduced to minimize leakage in limited space, and a methodological study on geometrical optimization has been conducted. As results of CFD analysis in various geometrical cases, optimum groove depths have been found to generate maximum sealing effects on gasoline fuel between the plunger and the barrel. This procedure offers a methodological way of an enhancement of plunger design for high-pressure GDI fuel pumps.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2121-2133
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• 1997

A finite element code is developed for 3-D self-contact problems, using continuum elements with a SRI(Selective Reduced Integration) scheme to prevent locking phenomenon by the incompressibility of rubber. Contact treatment is carried out in two ways : using the displacement constraints in case of rigid contact ; and imposing the same contact forces on two contact boundaries in case of self-contact. The finite element code developed is applied to the deformation analysis of C.V.joint boots which maintain lubrication conditions and protect the C.V.joint assembly from impact and dust. The boot accompanies large rotation depending on the rotation of the wheel axis and leading to the self-contact phenomena of the boot bellows. Since this contact phenomenon causes wear of the product and has great influence on the endurance life of the product, it is indispensable to carry out stress analysis of the rubber boots. In case of self-contact, various methods for determining contact forces have been suggested with an appropriate contact formulation. Especially, the types of penetration in self-contact are modularized to accelerate conputation with a contact algorithm.

• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.67-72
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• 2007

High Pressure Micro Jet (HPMJ) pad conditioning system was investigated as an alternative to diamond disc conditioning in copper CMP. A series of comparative 50-wafer marathon runs were conducted at constant wafer pressure and sliding velocity using Rohm & Haas IC1000 and Asahi-Kasei EMD Corporation (UNIPAD) concentrically grooved pads under ex-situ diamond conditioning or HPMJ conditioning. SEM images indicated that fibrous surface was restored using UNIPAD pads under both diamond and HPMJ conditioning. With IC1000 pads, asperities on the surface were significantly collapsed. This was believed to be due to differences in pad wear rates for the two conditioning methods. COF and removal rate were stable from wafer to wafer using both diamond and HPMJ conditioning when UNIPAD pads were used. Also, HPMJ conditioning showed higher COF and removal rate when compared to diamond conditioning for UNIPAD. On the other hand, COF and removal rates for IC1000 pads decreased significantly under HPMJ conditioning. Regardless of pad conditioning method adopted and the type of pad used, linear correlation was observed between temperature and COF, and removal rate and COF.

• Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.27-36
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• 2014

Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufacturability (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multiaxis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multiaxis freeform milling also need to be solved in a further study.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.675-682
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• 2020

Multi-wire sawing is the prominent technology employed to cut hard material ingots into wafers. This paper aimed to research the effect of diamond toughness index on the cutting performance of electroplated diamond wire. Three different toughness index of diamond abrasives were used to manufacture electroplated diamond wires. The cutting performance of electroplated diamond wire is verified through experiments, in which sapphire ingot are cut using single wire sawing machine. A single wire saw for constant load slicing is developed for the cutting performance evaluation of electroplated diamond wire. Choosing the cutting depth, total cutting depth, cutting force and wear of electroplated diamond wires as evaluation parameters, the performance of electroplated diamond wire is evaluated. The results of this study showed that there was a significant direct relationship between the toughness index of diamond abrasives and the cutting performance. Results demonstrated that diamond abrasive with a high toughness index showed higher cutting performance. However, all diamond abrasives showed similar cutting performance under low load conditions. The results of this paper are useful for the development of cutting large diameter ingots and cutting high hardness ingots at high speed.

• Tribology and Lubricants
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• v.37 no.4
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• pp.129-135
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• 2021

An air-bearing stage uses externally pressurized air as the lubricant between the stage and the rail. The supporting force generated by the supplied air makes the stage rise and move smoothly with extremely low friction. Mechanical contacts rarely happen, the bearing surfaces do not produce wear particles, and dust is not generated. It also has the advantage of having low energy loss and high precision. Because of its advantages, an air-bearing stage is used in several types of machines that require high precision. In this article, the effect of the pocket depth on the hammering phenomena of the air bearing is studied. An analysis program is developed to calculate the dynamic behavior of the stage by solving the Reynolds equation between the stage and the guideway and the equations of motion on the stage. The acceleration, constant movement, and deceleration are applied to the stage. The stage is modeled as a five-degree-of-freedom system. In the course of the dynamic behavior, the hammering phenomena occur under some special conditions. The deeper the pocket, the more unstable the behavior of the stage, and air hammering occurs when it exceeds a certain depth. In addition, the higher the supply pressure, the more unstable the behavior of the stage. However, hammering occurs even with a shallow pocket depth. Other conditions that affect the hammering phenomena are calculated and discussed.

• Corrosion Science and Technology
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• v.20 no.1
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• pp.26-36
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• 2021

Pipes operating in the seawater environment faces cavitation degradation and corrosion of the metallic component, as well as a negative synergistic effect. Cavitation degradation shows the mechanism by which materials deteriorate by causing rapid change of pressure or high-frequency vibration in the solution, and introducing the formation and explosion of bubbles. In order to rate the cavitation resistance of materials, constant conditions have been used. However, while a dynamic cavitation condition can be generated in a real system, there has been little reported on the effect of ultrasonic amplitude on the cavitation resistance and mechanism of composites. In this work, 3 kinds of epoxy coatings were used, and the cavitation resistance of the epoxy coatings was evaluated in 3.5% NaCl at 15 ℃ using an indirect ultrasonic cavitation method. Eleven kinds of mechanical properties were obtained, namely compressive strength, flexural strength and modulus, tensile strength and elongation, Shore D hardness, water absorptivity, impact test, wear test for coating only and pull-off strength for epoxy coating/carbon steel or epoxy coating/rubber/carbon steel. The cavitation erosion mechanism of epoxy coatings was discussed on the basis of the mechanical properties and the effect of ultrasonic amplitude on the degradation of coatings.

• Journal of Ocean Engineering and Technology
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• v.32 no.6
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• pp.492-501
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• 2018

The following results were obtained from a series of studies to accumulate data to reduce the coefficient of friction for press dies by performing tribological tests before and after the UNSM treatment of SM45C. The UNSM-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those for untreated materials. When loads of 5 N, 7.5 N, and 10 N were applied to the untreated material of SM45C, the coefficient of friction was approximately 0.76-0.78. With the large specimen, a value of 0.72-0.78 was maintained at a load of 50 N despite the differences in the size of the wear specimen and working load. Tribological tests of large specimens of SM45C treated with UNSM under tribological conditions of 100 N and 50 N showed that the frictional coefficient and time constant stably converged between 0.7 and 0.8. The friction coefficients of the small specimens treated with UNSM showed values between 0.78 and 0.75 under 5 N, 7.5 N, and 10 N. The friction coefficients of the SM45C treated with UNSM were comparable to each other.

• Composites Research
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• v.20 no.5
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• pp.49-55
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• 2007

Nanocomposite blade for dicing semiconductor wafer is investigated for micro/nano-device and micro/nano-fabrication. While metal blade has been used for dicing of silicon wafer, polymer composite blades are used for machining of quartz wafer in semiconductor and cellular phone industry in these days. Organic-inorganic material selection is important to provide the blade with machinability, electrical conductivity, strength, ductility and wear resistance. Maintaining constant thickness with micro-dimension during shaping is one of the important technologies fer machining micro/nano fabrication. In this study the fabrication of blade by wet processing of mixing conducting nano ceramic powder, abrasive powder phenol resin and polyimide has been investigated using an experimental approach in which the thickness differential as the primary design criterion. The effect of drying conduction and post pressure are investigated. As a result wet processing techniques reveal that reliable results are achievable with improved dimension tolerance.