• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1052-1055
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• 2001

In micro-drilling of brittle materials including glass, cracks occur at the exit surface. In drilling glass, the main type of crack is cone crack. Cone crack is generated by thrust force acting at the bottom surface of the workpiece. Cone crack size could be reduced by changing cutting conditions, but cone crack still existed. Two methods were proposed to prevent crack formation and perfect hole shapes were obtained. One method is attaching two glass plates with water and the other method is constraining two glass plates. The proposed methods eliminated tensile stress acting on the exit surface of glass and prevented crack propagation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1897-1901
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• 2003

Recently, with the development of semiconductor technology the miniaturization of products as well as parts and the products with high precision are being required. In addition as a national competitive power is increasingly effected by micro part development through micro machining and the secure of micro machining technology, the study of micro machining technology is being conducted in many countries. The goal of this study is to fabricate micro tool under the size of 30$\mu\textrm{m}$ and machine micro holes through micro tool fabrication by grinding, the application of ELID to grinding wheel and the measurement of surface roughness for micro tool.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.923-928
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• 1997

An MCP (Microchannel Plate) is a secondary electron multiplier to detect and amplify electrons. An MCP has many rnicrochannels whose diameters range from 10 to 100pm and whose lengths range from 40 to 100times of the diameter. Each microchannel of the MCP amplifies electrons over IOOOtimes by the secondary electron emission. Even though MCPs have high performance for electron amplification, the application of MCPs is limited to high performance electronic equipments because of their high fabricating cost and the limit of increasing their size due to the conventional fabrication process. Therefore, in this work, microchannels of the MCP are manufactured by micro-drilling to reduce the cost of the MCP and to increase their size. Alumina green body with epoxy binder was machined for fabricating microchannels using a high speed air turbine spindle and micro-drills with diamond grinding abrasives. Then alumina MCP was fabricated through the sintering of the machined alumina green body.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1787-1792
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• 2003

Recently with the development of semiconductor technology, the miniaturization of parts and products as well as their high precision is required. In addition, as the national competitiveness is increasingly affected by the development of the micro parts through micro machining technology, the study of the micro machining technology is being conducted in many countries. The goal of this study is to fabricate micro tools under the size of $20{\mu}m$ and to machine micro holes using them. The fabrication is done by grinding and the application of ELID to the grinding wheel. The surface roughness of the micro tools is measured to evaluate the study.

• 한국정밀공학회지
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• 제15권6호
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• pp.40-47
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• 1998

Drilling is an indispensable process in manufacturing of the die and mould and the other mechanical parts which needs high dimensional and surface accuracy. In this paper, a new type of drilling method was proposed in order to improve both processing efficiency and accuracy. Specifically, the helical motion using ball end mill tools, instead of normal drilling method, was applied to perform an effective hole machining. In this paper, an theoretical background of the new type of drilling method was established, and the feasibility of the proposed theory was proved by experiments, where proposed drilling process in the paper gave a different machining specification than general method did.

• 소성∙가공
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• 제30권2호
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• pp.74-82
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• 2021

Stretch-flangeability, which is the ability of sheet steels to be deformed into complex shapes, is a critical formability property in automobile body parts. In this study, the center-hole for hole expansion test, which is normally used to evaluate the stretch-flangeability of sheet steels, was prepared by both punching and electrical discharge machining (EDM) methods. Hole expansion ratio (HER) of punched hole was far lower than the HER of EDM drilled hole because of damage/crack in hole-edge due to punching process. The effect of hole-edge condition on HER was quantified by mechanical, fractographic and geometric factors. Based on these factors, the empirical equation used to determine HER for various sheet steels was derived using non-linear regression.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.353-354
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.267-268
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• 2011

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.519-524
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• 2001

These days, $Al_[2}O_{3}$ ceramic use all over the industry because dynamic function and special properties to compare traditional material. But $Al_[2}O_{3}$ ceramic is high hardness and brittleness materials. For this reason, it is very difficult to process. Therefor, In this paper, it was investigated that laser process parameter, which can produce appropriate quality of $Al_[2}O_{3}$ ceramic microhole machining utilized Nd:YAG laser and Excimer laser.

• 대한기계학회논문집A
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• 제35권5호
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• pp.543-547
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• 2011

원자력발전소의 이종용접부에서 일차응력부식균열이 발생하고 있으며 용접부의 잔류응력이 균열발생 및 성장에 기여할 수 있다. 용접부의 잔류응력은 기본적으로 용접에 의해 형성되지만 기계가공에 의해 표면잔류 응력상태가 변화할 수 있다. 본 논문에서는 기계가공이 원전재료인 SA508과 오스테나이트 스테인리스강에 표면잔류응력에 미치는 영향을 평가하였다. 이를 위해 SA508, TP304, F316L 재료를 연마, 연삭, 방전가공으로 가공한 후 표면에 형성되는 잔류응력을 측정하였다. 측정방법은 구멍뚫기법과 엑스선회절법을 사용하였다. 기계가공방법에 따라 각 재료에 미치는 잔류응력의 크기 및 방향, 잔류응력이 형성되는 깊이 등의 특성을 확인하였다.