• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1086-1092
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• 2007

This paper is concerned with the vibration analysis of a rectangular plate with multiple circular holes. On the contrary to the case of rectangular plate with multiple rectangular holes, it is very difficult to perform qualitative analysis on natural vibration characteristics because of geometrical inconsistency. In this paper, we applied the Independent Coordinate Coupling Method(ICCM) to the addressed problem, which was developed to compute natural vibration characteristics of the rectangular plate with a circular hole and proven to be computationally effective. The ICCM is based on Rayleigh-Ritz method but utilizes independent coordinates for each hole domain. By matching the deflection conditions for each hole imposed on the expressions, we can easily derive the reduced mass and stiffness matrices. The resulting equation is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the Independent Coordinate Coupling Method.

• 동굴
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• 제70호
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• pp.1-8
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• 2006

처마 끝에 열리는 고드름은 흔히 겨울철에 내린 눈이 지붕위에 쌓여 있다가 따사로운 햇살이 비치면 녹은 눈이 중력에 의해 흘러내리면서 영하의 찬 기류에 얼면서 성장하여 길게 매달린다. 그러나 땅바닥이나 물그릇 속에서 위로 자라 올라오는 역고드름은 특별히 그곳에서만 지상의 역 중력이 작용할 이유가 없기 때문에 간단히 해석되기가 쉽지 않다. 겨울밤에 정안수를 놋그릇에 떠놓고 공불기도를 올리다가 물이 어면서 나타나는 기이한 역 고드름은 물이 얼면서 생긴 표면의 숨구멍을 통하여 물보다 저밀도인 얼음의 체적이 불어서 밀려나오면서 생길 수 있으나, 이 현상만으로는 역고드름이 그렇게 크게 자랄 수가 얼다. 따라서 이 경우는 주변에서 불어오는 찬 기류가 지형지물에 부딪히면서 회오리쳐 소슬바람을 일으킬 때 일시적인 부압이 작용하여 그릇속의 물이 숨구멍을 통해 나오면서 얼어 성장되는 현상이 부가적으로 상승작용을 일으켜 길게 자라 올라온 것이다.

• 산업기술연구
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• 제19권
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• pp.1-7
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• 1999

This is the pre-study to pile up the basic technique for the electro-discharge machining in the field of micro-drilling. The machined chips are flowed out from the machining area by the flow arisen from the high speed rotation of the electrode. The cylindrical shape electrode, whose diameter is 0.5mm, is clamped by the three point clamping type clamper and the clamper is attached at the front shaft of the high speed rotating DC motor. The current for machining is controlled by pulse width modulation technique and the machining conditions such as frequency and duty ratio are changed to find out the effect of the variables for machined results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.967-972
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• 2008

This paper presents the free vibration analysis of a circular plate with a concentric square hole. The present problem deals with the numerical calculation of the natural frequencies and mode shapes of vibration of the structure by means of Independent Coordinate Coupling Method (ICCM). In this study, the boundary condition is the edge of the square hole is free and the outer circular plate is simply supported. Due to the geometric abnormality, this analysis does not permit an exact solution. Since the ICCM employs coordinate systems corresponding to each domain independently, the kinetic and potential energy expressions necessary for the Rayleigh-Ritz method can be easily obtained. Lastly, the kinematic relation is imposed. In this way, the eigenvalue problem can be easily set up. The numerical results show the efficacy of the ICCM and changes in natural frequencies and modes due to the square hole size.

• 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.

• 한국기계가공학회지
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• 제4권1호
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• pp.18-23
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• 2005

This paper reports experimental results on microdrilling process for silicon parts used in semiconductor equipments. An experimental system was developed consisting of a high speed precision machine, microscope system, and project profile instrument. The experimental results indicate that the amount of chipping at the entrance and exit of micro hole decreases as the spindle speed increases up to 18,000 rpm. At higher spindle speed, however, the amount of chipping increases rapidly. The amount of chipping and infeed rate show proportional relationship up to 20 m/min of infeed rate. Beyond that infeed rate, however, sudden increase in the amount of chipping has occurred.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2002년도 하계 학술대회 논문집
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• pp.84-89
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• 2002

소규모의 채소재배농가에서 육묘포트에 종자를 파종하는 작업은 대부분 손으로 파종하고 있으며, 중규모 이상의 채소재배농가에서는 간이파종기를 이용하거나 육묘공장에서 모를 구입하여 사용하고 있다. 간이파종기는 진공흡인력을 이용하는 종자흡인식과 평판의 구멍에 종자를 가두어놓았다가 낙하시키는 구멍배종방식 등이 주로 이용되고 있다(한국농업기계학회, 1998). 간이파종기는 대부분 플러그 육묘트레이에 사용할 수 있도록 되어 있으며, 포트수가 다른 플러그 육묘트레이를 사용하려면 새로운 포트규격에 맞는 파종장치를 구입하여야 하기 때문에 추가비용이 소요된다. 소규모 채소재배농가에서는 25, 36, 49공 등의 여러 가지 규격의 연결포트를 사용하고 영농규모가 작기 때문에 간이파종기를 구입하는 것이 부담스러운 실정이다. (중략)

• 한국정밀공학회지
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• 제27권5호
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• pp.7-13
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• 2010

The integrity and accuracy of the drilling hole are decided by positional error, diameter error, the roundness, the straightness, the cylindericity, size of the burr, the surface roundness and others. Among these parameters, positional error and diameter error have the most important parameters. The diameter error has been widely studied, but there has been little research done about the positional error due to the difficulty of measuring it. The measurement of hole location and diameter would be performed by CMM(Coordinate Measurement Machine). However, the usage of CMM requires much time and cost. In order to overcome the difficulties, we have developed a hole location and diameter error measuring device using machine vision. The developed measurement device attached to a CNC machine can determine hole quality quickly and easily.

• 한국소음진동공학회논문집
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• 제17권9호
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• pp.881-887
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• 2007

This paper is concerned with the vibration analysis of a rectangular plate with multiple rectangular holes. Even though there have been many methods developed for the addressed problem, they suffer from computational time. In this paper, we applied the Independent Coordinate Coupling Method(ICCM) to the addressed problem, which was developed to compute natural vibration characteristics of the rectangular plate with a rectangular hole and proven to be computationally effective. The ICCM is based on Rayleigh-Ritz method but utilizes independent coordinates for each hole domain. By matching the deflection conditions for each hole imposed on the expressions, we can easily derive the reduced mass and stiffness matrices. The resulting equation is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the Independent Coordinate Coupling Method.

• 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.