• 한국정밀공학회지
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• 제27권1호
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• pp.18-24
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• 2010

Efforts to obtain more efficient coupling of light from a laser diode to a single mode fiber have continued for various applications such as links for optical fiber communication systems. In TO-can package, configuration of optimized aspherical lens is bi-aspheric and its diameter is 2.4mm. We designed and fabricated aspherical coupling lens by means of glass molding technique under consideration of glass shrinkage. By controlling the aspherical profile error and surface roughness which were below 90nm and 10nm, respectively, we obtained the low coupling loss, 5.40dB, which was able to use for coupling a single mode fiber to laser diode.

• 한국표면공학회지
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• 제54권5호
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• pp.285-293
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• 2021

High-entropy TiAlCrSiN nano-composite coating was designed to improve mold life for high temperature liquid molding. Alloy design, powder fabrication and single alloying target fabrication for the high-entropy nano-composite coating were carried out. Using the single alloying target, an arc ion plating method was applied to prepare a TiAlCrSiN nano-composite coating had a 30 nm TiAlCrSiN layers are deposited layer by layer, and form about 4 ㎛-thickness of multi-layered coating. TiAlCrSiN nano-composite coating had a high hardness of about 39.9 GPa and a low coefficient of friction of less than about 0.47 in a dry environment. In addition, there was no change in the structure of the coating after the dissolution loss test in the molten metal at a temperature of about 1100 degrees.

• 통합자연과학논문집
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• 제9권1호
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• pp.62-66
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• 2016

To manipulate the mechanical properties of acrylonitrile butadiene rubber (NBR), addition of nano-sized silica on rubber was performed and nano-silica NBR composite (NSR) materials were fabricated by press molding. The effect of volume fraction of silica in the NSR on the spectroscopic and mechanical properties has been studied.

• 대한기계학회논문집A
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• 제34권5호
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• pp.575-582
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• 2010

최근 박육사출성형이나 마이크로 사출성형에서의 성형성을 높이기 위해 급속 금형가열 기술이 사용되고 있다. 고주파 유도가열은 전자기 유도현상을 이용하여 금형 표면만을 효율적으로 가열할 수 있어 급속 금형가열 기술로서 활용되고 있다. 본 연구에서는 고주파 유도가열 적용 사출성형 과정의 수치적 모사를 위해 전자기장 해석, 열전달 해석, 사출성형 유동해석을 연계한 통합적 전산모사 기법에 관한 연구를 수행하였다. 본 연구에서 제안된 통합적 전산모사 기법을 유도가열 적용 박육 사출성형의 해석에 적용하여 실험결과와 비교하였고, 특히 금형온도 경계조건의 부여방식에 따른 해석의 신뢰성에 대한 고찰이 이루어졌다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.302-305
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• 2007

In recent years, many researches on new storage media with high capacity and information are developing. For manufacture of optical storage with high capacity, the injection molding process is generally used. In order to increase the filling ratio of the injection molding structure, the injection molding process required for high injection pressure, packing pressure and temperature control of the mold. However, conventional injection molding process is difficult to increase the filling ratio using injection master with the range of several nanometers and high aspect ratio. In order to improve and increase filling ratio of nano-structure with high aspect ratio, the active temperature control of injection mold was used. Experimental conditions were used injection pressure, time and temperature. Consequently, by using the peltier device into injection mold, we carried out the efficient and active temperature control of mold at low cost.

• 소성∙가공
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• 제14권9호통권81호
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• pp.741-750
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• 2005

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.368-370
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• 2007

AAO(Anodic Aluminum Oxidation) method has been known that it is practically useful for the fabrication of nano-structures and makes it possible to fabricate the highly ordered nano masters on large surface and even on the 2.5 or 3D surface at low cost comparing to the expensive e-beam lithography or the conventional silicon processing. In this study, by using the multi-step anodizing and etching processes, highly ordered nano patterned master with concave shapes was fabricated. By varying the processing parameters, such as initial matter and chemical conditions; electrical and thermal conditions; time scheduling; and so on, the size and the pitch of the nano pattern can be controlled. Consequently, various alumina/aluminum nano structures can be easily available in any size and shape by optimized anodic oxidation in various aqueous acids. The resulting good filled uniform nano molded structure through hot embossing molding process shows the validity of the fabricated nano pattern masters.

• 대한기계학회논문집A
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• 제32권6호
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• pp.481-487
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• 2008

Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers an experimental investigation of induction heating in order to rapidly raise the mold temperature. It is observed that the mold surface temperature is raised up to $200^{\circ}C$ in 2 seconds. This induction heating is applied to injection molding of a flexspline for a plastic harmonic drive, which has difficulty in cavity filling because its minimum thickness is only 0.35 mm. The induction heating is then successfully implemented on this ultra-thin wall molding by raising the mold surface temperature around the glass-transition temperature of the molding material.

• 대한금속재료학회지
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• 제49권1호
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• pp.32-39
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• 2011

The present investigation was performed on the die compaction and sintering behavior of Fe micro-nano mixed powder with a mixed binder for powder injection molding. Warm die compaction of the feedstock for simulation of the static injection molding process was conducted using a cylindrical mold of 10 mm diameter at $100^{\circ}C$ under 4MPa. The die compaction of the micro-nanopowder feedstock underwent a uniform molding behavior showing a homogeneous distribution of nanopowders among the micropowders without porosity and distortion. After debinding, the powder compact maintained a uniform structure without crack and distortion, leading to a high green density of 64.2% corresponding to the initial powder loading of 65%. The sintering experiment showed that the micro-nanopowder compact underwent a near full and isotropic densification process during sintering. It was observed that the nanopowders effectively suppressed the growth of micropowder grains during densification process. Conclusively, the use of nanopowder for PIM feedstock might provide a new concept for processing a full density PIM parts with fine microstructure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.840-843
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• 2004

UV molding is a process for integrating micro/nano polymeric optical components on optoelectronic modules. In the present study, a microlens array for vertical cavity surface emitting laser(VCSEL) to fiber coupling was designed, integrated and tested. At the design stage, design variables ware optimized to maximize the coupling efficiency, and tolerance analysis was carried out. At the integration stage, the UV transparent mold was fabricated and the microlens array on VCSEL array was integrated by UV molding process. Finally the coupling efficiency of VCSEL to fiber was measured and analyzed.