• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.699-700
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• 2013

• 드라이브 ㆍ 컨트롤
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• 제9권3호
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• pp.56-66
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• 2012

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.402-407
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• 2002

Laminate tooling process is a fast and simple method to make metal tools directly for various molding processes such as injection molding in rapid prototyping field. Metal sheets are usually cut, stacked, aligned and joined with brazing or soldering. Through the joining process, all of the metal sheet layers should be rigidly joined. When joining process parameters are not appropriate, there would be defects in the layers. Among various types of defects, non-bonded gaps of the tool surface are of great importance, because they directly affect the surface quality and dimensional accuracy of the final products. If a laminate tool with defects has to be abandoned, it could lead to great loss of time and cost. Therefore a repair method for non-bonded gaps of the surface is essential and has important meaning for rapid prototyping. In this study, a rapid laminate tooling system composed of a CO2 laser, a furnace, and a milling machine was developed. Metal sheets were joined by furnace brazing, dip soldering and adhesive bonding. Joined laminate tools were machined by a high-speed milling machine to improve surface quality. Also, repair brazing and soldering methods of the laminates using the $CO_2$ laser system have been investigated. ill laser repair process, the beam duration, beam power and beam profile were of great importance, and their effects were simulated by [mite element methods. The simulation results were compared with the experimental ones, and optimal parameters for laser repair process were investigated.

• Design & Manufacturing
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• 제2권3호
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• pp.28-31
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• 2008

In recent, the demand of high-productivity injection mold is increased because of the growth of international packaging market which is induced by an increase of population. The increase of productivity leads to the large-capacity injection molding machine and peripheral devices. For solving this problem, the stack mold which is based on the exsiting machine and device has researched in advanced countries actively. In this paper, as the preliminary research of stack mold development, the stack mold which has 2 level ${\times}4$ cavity was designed and fabricated. Besides, the motion and structural analysis were performed to verify the stability of developed stack mold.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 자성 및 자성재료 국제학술대회
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• pp.95-95
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• 2013

The NdFeB magnet can be classified into the sintered magnet and bonded magnet. The former has superior magnet characteristics but the degree of freedom in shape is highly restricted, whereas the latter has a high degree of freedom, but its magnet characteristics are inferior to the former. When a NdFeB magnet is used at the elevated temperature, part of Nd must be replaced with a high priced Dy to increase its coercive force. For these reasons, a Dy free and high performance NdFeB bonded magnet is desired strongly. The author successfully developed a Dy free NdFeB anisotropic bonded magnet based on discovery of new phenomena called as d-HDDR reaction and its mass production process such as a thermally balanced hydrogen reaction furnace, micro capsuled powder, compression molding / injection molding under magnetic field, magnetic die and so on. Applied to DC brush seat motor for automotive use, the motor has become 50% small in size and weight. The commercialization of a half sized motor for automotive use has been realized up to the market share of 30%. At present, its commercialization is extending to various types of motors such as power tool, ABS motor, wiper motor, window motor, electric bike power motor, and compressor motor. It is expected that the applications will be increasingly enlarged to EV motor, wind generator, EPS motor, washing machine, and glass cutting machine. This innovative technology has realized Dy free high performance magnet and mudt make big contribution to not only rare element strategies but also energy conservation.

• 한국기계가공학회지
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• 제21권6호
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• pp.98-106
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• 2022

Among the parts assembled in the gas receiver of a marine engine, the titanium alloy stainless steel (STS 316Ti) wire mesh serving as a filter was broken, and the related part, the turbine fan of the turbocharger, was damaged. In this study, a sample of the grid wire mesh was collected and the cause of breakage was analyzed, and a method of minimizing the dent mark caused by the mold during wire forming, which is one of the most direct causes, was studied. In addition, the optimum mold shape was realized through FEM simulation, and the wire wave molding machine capable of controlling the speed was improved by supplementing the problems of the existing wire wave molding machine, thereby improving durability with minimal dent marks.

• 한국재료학회지
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• 제30권12호
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• pp.650-654
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• 2020

A combination of Polycarbonate (PC) material and Polymethylmethacrylate (PMMA), fabricated using an injection molding machine, has been investigated to determine its advantages, as studied in Ref. 1). This paper aims to investigate the optimization of PMMA/PC blend for both tensile yield strength and impact strength. Furthermore, interaction effects of process conditions on mechanical properties including tensile yield strength and impact strength of PMMA/PC blend by injection molding process are interpreted in this study. Tensile and impact specimens are designed following ASTM, type V, and are fabricated by injection molding process. The processing conditions such as melt temperature, mold temperature, packing pressure, and cooling time are applied; each factor has three levels. As a result, in comparison with optimization of separated responses, mechanical properties of PMMA/PC are found to decrease when optimizing both tensile and impact strengths simultaneously. The melt temperature is found to be the most significant interaction parameter with the mold temperature and packing pressure. In addition, there is more interaction between the mold temperature and cooling time. This investigation provides a useful understanding of the control of injection molding processing of polymer blends in optical application.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.203-206
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• 2008

본 연구는 고체 추진기관에 적용되는 내열재를 autoclave 방식이 아닌 hot press molding으로 제작하여 연소관에 접착 가능한 상태의 내열재로 제작하는데 초점을 두고 있다. EPDM/kevlar를 기본 조성으로 내열재 원료가 구성되고, 미가류 sheet 상태로 공급된다. 전방 내열재는 금형을 사용하여 preform 상태로 1차 제작하고, boots를 구형하기 위해 두개의 preform 사이에 modified nylon film을 사용하여 제작 하였다. 실린더 부위를 포함하고 있는 후방 내열재는 특별히 설계된 하나의 금형으로 제작되었고, boots 부위는 초경합금 칼날을 가지고 있는 장비에 의해 실현되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.41-41
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• 2010

In this research, to study tungsten carbide alloy(Co 0.5%) ultra precision turning possibility that is used Glass Molding Press(GMP) using conventional (Rake angle $-25^{\circ}$) single crystal diamond bite observed machining surface condition, surface roughness($R_a$), diamond bite cutting edge after tungsten carbide alloy ultra precision turning. Suggested and designed optimum chamfer bite shape to suggest ultra precision optimum bite using Finite Element Analysis(FEM). After machining tungsten carbide alloy ultra precision turning using optimum chamfer bite and comparing with conventional bite machine result and studied optimum chamfer bite design inspection and also tungsten carbide ultra precision turning possibility for high temperature compression glass lens molding.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.698-701
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• 2005

We have investigated experimentally a nano patterning using electron beam lithography for the nickel stamper fabrication. Recently, DVD and Blu-ray disk(BD) have nano-scale patterns in order to increase the storage density. Specially, BD has 100nm-scale patterns which are generally fabricated by electron beam lithography. In this paper, we found optimum condition of electron-beam lithography for 100nm-scale patterning. We controlled various conditions of EHP(acceleration voltage), beam current, dose and aperture size in order to obtain optimum conditions. We used 100nm-thick PMMA layer on a silicon wafer as photoresist. We found that EHP was the most dominant factor in electron-beam lithography.