• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.265-265
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• 2004

최근 IT산업으로 대표되는 광통신 및 광신호 전달에 이용되는 광 반사경 및 렌즈어레이, 광가이드 판넬(BLU, FLU)등 광부품의 수요가 급증하고 있고, 이의 생산을 위한 다양한 제조공정이 연구 개발되고 있다 근년까지 이러한 마이크로 광부품의 제조방법은 포토리소그래피, 에칭기술을 베이스로 한 MEMS 기술, PDMS를 이용한 복재기술에 크게 의존하고 있다. 기계적 가공법으로는 오래전부터 초정밀 경면 선삭이나 연삭에 의한 마이크로 렌즈와 미세 패턴의 금형가공이 이루어져 왔다.(중략)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.267-272
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• 2011

The behavior of abrasive wear on counterpart roughness of glass fiber reinforcement polyurethane resin (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. The major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the counterpart roughness the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding velocity was higher and the counterpart roughness was rougher in wear test.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.9
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• pp.5-21
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• 1995

공작기계의 가공 정밀도에 영향을 주는 주요 요인은 정적특성(Static behavior), 동적특성(Dynamic behavior), 그리고 열적특성(Thermal behavior)에 있다는 것은 이미 언급한 바 있다. 열적영향으로 인한 정밀도를 안정시키는 완전한 해결책은 아직 발견되지 못하고 있다. 그 이유는 공작기계 자체뿐만 아니라 부품들이 복잡하고 공작기계의 내부, 기계와 주위환경사이에 복잡한 열적상호작용이 존재하고 있기 때문이다. 그럼에도 불구하고 공작기계에는 더욱 높은 생산능력과 가공정도에 대한 요구가 점점 커지고 있다. 과거 40년 간에 걸쳐 공작기계의 열적거동에 대한 연구가 활발히 진행되어 왔지만 일반적으로 적용하여 만족할 만한 열적 불안정의 해결책은 아직 나오지 않고 있으며 단지 여러가지의 기계구성요소, 즉 Spindle, Column이나 Bed와 같은 본체의 구조나 Table이나 Slide에 대해서 열적 최적화를 얻는 노력이 집중적으로 행해지고 있다. 공작기계 의 열변형에 대한 연구는 1950년대부터 시작되었으며, 선반이나 연삭기의 열변형 측정기술과 해당하는 설계변경 방법 그리고 냉각을 함으로서 열적 불안정을 극복시키는 방법이 주요 연구과제였으나 1960년대 후반에는 구성 요소의 온도분포와 열의 흐름에 관한 수학적 모델을 한들어 해석적 수법올 열적 거동의 연구가 행하여졌었다.

• Journal of the Korean Professional Engineers Association
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• v.30 no.6
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• pp.144-152
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• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted to be studied in this paper. Wheels, that are employed for the smooth and mirrow finishing of die materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond abrasive grains were bonded firmly by a melamine to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work sufaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are explained.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.962-967
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• 2003

Recently, environmental pollution has become a serious problem in industry, and many researches have been done in order to preserve the environment. The coolant, which promotes lubrication, cooling and penetration, contains chlorine, sulfur and phosphorus to improve the machining efficiency. These additives, which move around into the air during machining, pollute working. Therefore, many researches on how to reduce the amount of coolant during machining have been carried out. However, to reduce even small amount of coolant causes high temperature of a workpiece and it brings thermal defects. In this study, the experiments of wet & dry grinding using cooling methods (using coolant only, mist and compressed cold air only) are performed to solve the problem of environmental contamination and to get a better surface integrity of a workpiece by comparing surface roughness, roundness and residual stress.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.8
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• pp.5-18
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• 1995

공작기계의 정밀도는 정적, 동족 그리고 열적 특성에 좌우된다는 사실은 4장 Fig. 4-3의 예를 들어 충분히 설명한 바 있다. 4장에서는 주로 정적특성(Static behavior)에 대해서 설명한 바 있으나 이번에는 동적특성에 대해서 논술하고자 한다. 진동문제의 해소는 가공기술의 향상, 공작기계의 진보에 절대적으로 중요한 과제이다. 절삭, 연삭 및 미세가공에서 진동이 발생하여 가공을 계속할 수 없게 되거나 가공을 했다해도 가공표면에 Chatter mark를 남기게 되어 요구 품질을 만족할 수 없는 경우가 있다. 공작기계는 많은 부품을 조립하여 만든 것이기 때문에 동적현상은 다질량(Mult-mass)으로 고려해서 진동을 생각해야 겠지만 대부준의 경우 단위 질량(Single-mass) 으로 생각하여 Fig. 5-1과 같이 그 진동이론을 종합하고 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.103-110
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• 1991

본 연구에서는 최근들어 첨단 가공기술로서 중요시되고있는 초정밀 경면가공기술의 기본원리를 이해하고 관련지식을 습득하여 향후 보다 나은 상태의 경면가공을 위한 기초를 확립하는데에그 목적을 두었다. 실험을 위한 공작기계는 초정밀 만능 연삭반( high precision universal grinder)에 플라이컷(fly-cut)방식에 의한 절삭가공이 가능 하도록 여러가지장치들을 부착하였으며, 절삭공구는 천연 다이아몬드를 사용하고, 피삭재는 A1-Cu-Ni-Mg 합금을 사용하였다. 본 실험에서는 주어진 조건내에서 어느정도의 표면 조도를 달성할수 있는지를 알아보고 그 과정을 통하여 공작기계, 공구, 피삭재등의 영향과 절삭력, 칩, 표면상태등을 고찰하여 여러가지 현상을 규명하여 향후의 발전을 위한 대책에 활용하고자 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.495-502
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• 2010

The effect of load and sliding speed on abrasive wear characteristics of glass fiber/polyurethane (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. Experimental results showed that the surface roughness of the GF/PUR composites was increased as applied load was higher in wear test. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on applied load and sliding speed for these composites. It could be verified by scanning electric microscopy (SEM) photograph of surface tested that major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking.

• Journal of the Semiconductor & Display Technology
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• v.10 no.3
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• pp.35-42
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• 2011

This paper describes the characteristics of high speed grinding and the influence of wheel surface speed V and a grindability of the grinding materials. The various fine ceramics pieces was ground by metal and vitrified bonded diamond wheel. The surface roughness of fine ceramics(Zirconia($ZrO_2$), Silicon Carbide(SiC), Silicon Nitride($Si_3N_4$), Alumina($Al_2O_3$)) decreases from $0.05{\mu}m(R_{max})$ to $0.025{\mu}m(R_{max})$ when the wheel speed at grinding point increases the wheel speed. Relation between the temperature at grinding point and surface roughness was linear. Abrasive jet machining(AJM), a specialized from of shot blasting, is considered one of the most helpful micro machining methods for hard and brittle materials such as glasses and ceramics by constant pressure grinding.