• 한국정밀공학회지
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• 제20권2호
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• pp.162-167
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• 2003

This paper is the study on stress analysis for tooth modification of high speed gear using a finite element method. Gear drives constitute very important mechanisms in transmitting mechanical power processes which compromise several cost effective and engineering advantages. The load transmission which occurred by the contacting surfaces arises variable elastic deformations evaluated through finite element analysis. The automatic gear design program was developed to model gear shape precisely. This developed gear design system was used by pre-processor of FEM packages. The distribution of stresses at contacting surfaces was examined when gear tooth contacts. And this paper proposes a method for the tooth modification after carrying out stress analysis using a finite element method.

• 한국식물병리학회지
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• 제12권1호
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• pp.121-128
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• 1996

농업 기상 자료의 수집 및 식물병 예찰 절차를 통합한 시스템을 -32비트 개인용 컴퓨터 운영 체계인 OS/2에서 개발하였다. 통합 시스템은 무인기상관측기(AWS)로부터 자료 수집을 하는 절차, 준실시간 기상자료로부터 병예찰을 하는 절차, 기상 정보와 병예찰 정보를 글과 그림으로 출력하는 절차의 세 부분으로 나뉘어 있다. 통합 시스템은 여러 지역의 실시간 기상 자료를 수집하며 기상 자료를 이용하여 각 지역의 병예찰 정보를 즉시 생성한다. 본 연구에서는 기상 자료를 이용한 병예찰 모형의 예로서 도열병 예찰 시뮬레이션 모형을 사용하였다. 또한 식물병 예찰을 위하여 무인기상관측기가 갖추어져야 하는 최소한의 요구 사항을 검토하였다. 본 시스템은 각종 식물병 예찰 모형의 개발과 관련하여 각 모형의 구동을 위하여 쓰여질 수 있을 것이다. 현재 각 농촌진흥원과 지도소에는 많은 수의 무인기상관측기가 설치되어 있으므로 이를 이용하여 본 시스템을 실용화 할 수 있을 것이다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.505-506
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• 2006

Size reduction of micro-aperture using additional deposition is presented in this study. PECVD process was used for additional deposition. Rate of deposition is different with deposition direction because corners of shadowmask membrane have a taper. Deposition into backside showed better than deposition into frontside with size reduction. Shadowmask membrane with two materials has stress because of the difference of a coefficient of thermal expansion The cantilever of membrane bend to opposite direction of deposition. Deposition to both frontside and backside could reduce inside stress.

• 한국정밀공학회지
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• 제16권10호
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• pp.94-100
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• 1999

Micro-EDM is widely used in machining of miro-parts such as micro-shafts and micro-holes. In order to select proper machining conditions and to reduce the machining time, it is necessary to understand machining characteristics under various machining conditions. Micro-hole machining tests were performed with round shape electrodes with different capacitances and voltages of the power source. The effects of the electrode rotational speed and diameter on the machining rate were also observed. From the experimental results, it was found that capacitance and voltage have significant effects on machining rate and the machined surface integrity. With higher capacitance and higher voltage, higher machining rate was observed together with poorer surface integrity. The electrode diameter was also found to have an effect on the machining rate and electrode wear.

• Journal of Chest Surgery
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• 제26권12호
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• pp.955-958
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• 1993

Pseudocoarctation is extremely rare and is due to elongation and kinking of aortic arch which mimiks true coarctation but has no pressure gradient across it. This state is essentially benign entity and needs no surgical intervention, but it frequently tends to progress into the aortic aneurysm that results in compressive symptom due to mass effect and unawared rupture and death.We experienced a descending aortic aneurysm secondary to pseudocoarctation. The patient was 53 year-old female presented as easy f`atiguability and facial flushing. The aortogram revealed tortuous and enlarged aorta at the level of ligamentum arteriosum. The aneurysm was resected and was end-to-end anastomosed successfully under partial cardiopulmonary bypass. The postoperative course was uneventful and the patient was discharged on postoperative 10 day.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제8권2호
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• pp.61-68
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• 2004

The purpose of this study is to develope and analyze the assessment items which can be used in evaluation of the fraction computation ability for fifth grade students. The item development team consists of three elementary school teachers and three mathematics education expert. The developed items was analyzed item analysis after applying to 135 fifth grade students. As a results of item analysis, it shows meaningful over the level of a standard basis: reliability: 0.80; validity: item 1(1.05), item 2(1.10), item 3(.85), item 4(.90), item 5(1.08); item difficulty: item 1(-.22), item 2(-.41), item 3(.23), item 4(.40), item 5(-.01); item discrimination: item 1(.73), item 2(.73), item 3(.67), item 4(.51), item 5(.56). This means that the test tool could be useful in the evaluation of the fraction computation ability.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.641-645
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• 2002

In case of aluminum-cased battery, The ratio of height and base of square is generally above the ten times, square-shaped and problem of non-axis symmetry. It is typical model to set up the analysis method of finite element. The reliable analysis of finite element method is suggested, which is used to investigate the possibility that multi-stage deep drawing and ironing used currently is replaced by backward impact extrusion favorable in the respect of cost production and productivity. The influence of parameter was analyzed and compared, which was considered to analyze the process of large deformation plasticity such as extrusion. Die and billet was made as the same shape of finite element model. The results of experiment show good forming without the rupture and wrinkles with the optimum velocity 100mm/sec obtained by analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.792-795
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• 2002

In previous researches, it is reported that Ti-10Ta-10Nb is robuster than Ti-6A1-4V which is used as a biomaterial in a experiment of cytotoxicity. Ti-10Ta-10Nb has enough hardness to be required as a biomaterial because the change of its hardness can be controlled more than 100% according to heat treatment condition and manufacturing condition. There are many hardness changing condition including Cast Homogenization, Solution treatment. Forging, Rolling in this research. The changing form and amount of new Ti-10Ta-10Nb to be developed in this researches, are measured as quantitative. Specially, the changing hardness amount of the specimen that is manufactured in single phase temperature, i.e. 80$0^{\circ}C$, are measured in case of high temperature rolling and high temperature cast condition.

• 한국정밀공학회지
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• 제18권2호
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• pp.111-118
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• 2001

Tungsten probe is the most important part of a probe card, which is widely used for the performance test of wafer chips. Electro chemical etching becomes an exclusive choice for mass production of the tungsten probes. In the mass production, not only the shape of the probe but also the shape distribution of machined probes is important. A new method is proposed for the mass production of the tungsten probes. Tungsten wires are separated by a distance, and dipped into electrolyte. The dipping rate is controlled to shape the probes. Several experimental tests are performed to study the machining characteristics. From the test results, machining parameters including electrical conditions and anode position showed significant influences on the shape, repeatability, precision and quality of sharp tips.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2004년도 학술발표회
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• pp.484-489
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• 2004

경사식 방파제에 대하여 수리모형실험을 통하여 방파제의 전사면과 저면에 작용하는 파압을 직접 측정하여 파압의 공간적 분포를 파악하여 보았다. 실험의 길과는 기존의 경사식 방파제에 대하여 파압에 대한 연구는 거의 없기 때문에 Goda(1989, 2002)가 제시한 전사면에 대한 이론식과 비교하여 보았다. 실험은 특정적으로 제시된 방파제 단면에 대한 실험이 아니고, 가상적인 단면을 선정한 후 파랑 및 수심 등의 제조건을 감안하여 파형경사를 산정하고, 이애 맞는 파고와 주기를 산정한 후 제반 해안수리학적 특성중 반사율과 처오름 높이, 사면 및 저면에 작용하는 파압을 직접 측정하여 보았다. 실험결과 전사면에서의 파압 분포는 Goda의 이론식과 경향은 비슷하나 크기는 차이가 나이에 대한 보정은 필요한 것으로 나타났으며, 저면에서의 파압도 측정이 되었지만 이것이 지반지지력에 어떠한 영향을 미치는지는 좀 더 많은 연구가 필요할 것으로 판단되었다.