• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.285-291
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• 2002

The shearing process for the sheet metal is normally used in the precision elements such as a frame of TFT-LCD or lead frame of If chips. In these precision elements, the burr formation prevents the system assembly and needs the additional burr removing process. In this paper, we developed the small size NC punching system which has an aligning kinematics between the rectangular shaped punch and die. The punch is driven by an ai cylinder and the sheet metal is moving on the X-Y table system which is driven by two stewing motors. The microprocessor control the whole system and communicate with the monitoring PC by RS232C serial communication protocol. The graphic user interface program in PC monitors nil control the punching system. The cross shaped joint hinge supports the punching die and positioned by two differential screws, whose are installed in perpendicular directions. The aligning between the punch and die is performed using the sheets of half thickness(0.1mm Brass) of the real process for the frame of the TFT-LCD. Using half thickness Brass, the burr formation is magnified and we can decide the aligning direction more easily then using the real thickness(0.2mm) Aluminum. In this paper, the aligning results are measured manually using the SEM photographs and we hope to make the automated aligning procedures using some kinds of image processing techniques.

• 전기학회논문지
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• 제65권12호
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• pp.2113-2118
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• 2016

The precise detection of electric leakage point of underground power cable is very important to reduce cost and time of maintenance and prevent electric shock accident through expedite repair of electric leakage point. This paper proposes a electric leakage point detection system underground power cable using of half-period modulated transmission waveform and earth electric potential measurement. The developed system is composed of transmitter to generate the wanted pulse waveform, receiver to measure and display earth electric potential by the transmitted pulse in electric leakage point and PC Software program to display of GPS coordinate on detection cable line. The performance of the electric leakage point detection system was tested in the constructed underground cable leakage detection test bed. The test results on signal generation voltage precision of signal transmitter, mean detection earth voltage, mean detection leakage current and electric leakage point detection error showed the developed system can be used in electric leakage point detection underground power cable.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1999년도 국제 심포지엄 Proceedings of International Symposium on 친환경농업과 기계화방향
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• pp.137-159
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• 1999

Over the last three decades, Korean farming system has been directed to maximum agricultural production and to increase farmer's income through adoption of high-yielding crop varieties and high input of agrochemicals . These farming practices have resulted in problems of water-quality deterioration, soil degradation , and food safety. At present, over 40 million tones of animal waste are bing produced annually, which amounts to disposing the waste at the annual rate of 20 tones per ha in the total area of farming land in Korea. Nearly a half of total available water resources is used as irrigation water predominantly for rice paddy field. Thus, non-point source contamination of the water resources has been linked to agriculture across the nation. However, the extent to which agriculture contributes to the water quality is not fully known. Recently, Korean government provided various institutional measures to reduce the negative impacts of agricultural practices on the environ ental quality, and the Agricultural Environment Act was also passed by the legislature in 1998 and became effective January 1999. This Act does not cover the broad spectrum of the sustainable agriculture ; thus, the limited incentives within this Act are arguably ineffective to control the non-point source pollution. Recently new bulk blending of fertilizers(BB fertilizer) are bing produced (100, 000 tones in 1998) with Government subsidies. The BB fertilizers are to balance N-P-K ratio in the soils . Although the use of the BB fertilizers are encouraged with Government subsidies, non-point source pollution is still serious and will become worse. Precision farming is regarded as a new means for sustainable agriculture. It is a new technology that modifies the existing techniques and incorporates new one such as GIS, GPS , differential applicator to produce a new set of tools for the farmer to use. Precision farming, however, has constraints for individual farming practices. For exam le , farm size or parcel unit of each farmer is too small to adopt the precision agriculture on farmhouse-hold bases and farmer's ability to adopt the new technology is limited. However, it would be appropriate to establish local or regional cooperatives to operate such a precision farming system. It is recommended that Government provide sufficient incentives to help establish local and/or regional cooperatives.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.99-99
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• 2008

대구경, 고품질 GaN 단결정 기판은 HVPE 방법을 이용하여 제조하였다. 이때 성장 방법은 기판인 $Al_2O_3$ 단결정 기판을 질화처리 하였으며, 이종기판 성장 시 야기되는 격자 불일치와 성장 후 냉각동안에 열팽창 계수의 불일치로 야기되는 휨이나 crack 발생을 제거하기 위하여 step-growth 방법을 사용하였다. 사파이어 위에 성장된 GaN의 기판은 두께가 380um이며, 직경은 3"로 crack 발생은 없었으며, $600^{\circ}C$에서 레이저 분리 방법을 이용하여 사파이어와 분리하였다. 그러나 분리된 기판은 이종기판과의 접촉면에서 고밀도 결함발생으로 인하여 휨이 발생하였으며, 표면을 연마한 후 DCXRD의 FWHM은 107 arcsec, PL을 이용한 결함밀도는 $6.2\times10^6/cm^2$으로 나타났다.

• 대한기계학회논문집A
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• 제38권2호
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• pp.219-225
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• 2014

폰 카메라용 렌즈모듈을 구성하는 각 단렌즈의 방향성을 고려한 자동 조합시스템을 개발하였다. 먼저 유동해석을 통하여 렌즈모듈의 조합성 도출 영향인자인 복굴절과 사출성형 조건의 상관성 및 조립 방향성에 따른 수율의 관계를 조사 하였다. 하나의 조립모듈에서 렌즈와 스페이서의 한 세트를 조립하도록 설계하여 생산성 향상 및 장비크기를 최소화하여 기존 장비의 약 25 %정도로 축소가 가능하였다. 또한, 기구적인 정렬기구인 센터링 기구 및 배럴가이드 적용하여 추가적인 비전시스템 없이 사이클 타임의 단축이 가능하였다. 개발한 시스템은 모듈러 설계를 통하여 픽커 및 가이드 등 일부 부품만의 교체로 생산모듈 변경에 대응 가능하도록 하여 급변하는 시장변화 및 소량생산에도 적용 가능하도록 제작되었다.

• 대한원격탐사학회지
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• 제17권3호
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• pp.231-242
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• 2001

2-pass Differential Interferometry(DInSAR)에서는 digital elevation model(DEM)을 이용하여 interferogram에서 지형의 위상을 제거함으로써 지형과 변위에 대한 두 가지의 위상 효과를 분리한다. 이 방법은 phase unwrapping 단계가 필요 없다는 장점이 있는 반면에 사용되는 DEM의 정밀도가 높아야 한다는 제약이 있다. 2-pass DInSAR를 이용하여 미세한 지각 변위의 인지가 가능하나, 두 SAR 자료의 관측기간 중 변위가 없는 경우에는 잔여 위상은 사용된 DEM의 오차를 반영한다. 따라서, 본 연구에서는 DEM의 정밀도를 향상시키기 위해 낮은 정밀도의 DEM을 사용하는 방법에 대한 기초 연구로써 아산만 지역에 2-pass DInSAR 방법을 시험 적용하였다. ERS 1/2 tandem SAR 자료와 DInSAR 계산을 위해 DTED level 0을 사용하였으며, 얻어진 결과의 정밀도 분석을 1:25,000 수치지도와 비교하였다. 생성된 DEM의 절대 고도 오차 평균 9.7m이며, 이는 일반적인 InSAR 방법에 의해 얻어진 DEM의 절대 고도 오차 평균 15.8m와 DTED level 0의 절대 고도 오차 평균 18.1m보다 향상된 결과를 보였다. 이 방법은 사면의 경사도가 높은 경우 InSAR에서 나타나는 layover 영향을 효과적으로 줄일 수 있다. 즉, DInSAR 방법은 지각의 변위 관측뿐만 아니라 지형 고도 자료가 부족한 지역에서 정밀도를 향상시키는데 활용될 수 있음을 보여주고 있다.

• 한국방사선학회논문지
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• 제11권6호
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• pp.509-515
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• 2017

본 연구는 EBT3 필름을 이용하여 감마나이프 퍼펙션 모델의 3차원적인 선량분포 측정하고 기준값과 비교 분석하여 표준화된 측정방법의 기초로 활용하고자 한다. 2개 종합병원에 설치된 감마나이프 퍼펙션 모델의 선량 분포를 EBT3 필름을 이용하여 정확도와 정밀도를 평가하였다. 정확도 평가를 위해 4 mm 콜리메터를 사용하여 기계적인 중심축과 선량중심축의 일치도를 측정하였다. A병원 0.098 mm, 0.195 mm 이며 B 병원 0.229 mm, 0.223 mm 로 허용 오차 0.3 mm 이하로 측정되었다. 정밀도 평가는 4, 8, 16 mm 콜리메터(collimater) 각각의 x, y, z 3차원면 에서의 반치폭(FWHM : Full Width at Half Maximum)을 이미지-제이 프로그램을 이용하여 평가하였다. A 병원은 -0.283~0.583 mm, B 병원은 -0.857~0.810 mm로 50%선 ${\pm}1mm$ 이하의 기준에 적합하였다. 이미지-제이 프로그램을 이용한 선량 분포 분석의 경우 측정자 간의 오차가 발생 가능함으로 측정점에 대한 명확한 기준을 확립할 필요가 있으며, 감마나이프 방사선 수술이 시행되어지는 고선량 영역에서 사용 가능한 선량영역이 높은 필름을 이용한 치료계획과 실제 치료 조사면의 비교가 필요하다고 생각된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.279-282
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• 2002

In this paper, we present a new method for monitoring of ECU's self diagnostic signals of vehicle without wire. In order to measure the ECU's self diagnostic signals, the interfaced circuit is designed to communicate ECU and a designed display terminal according to the ISO, SAE regulation of communication protocol standard. A 80C196KC processor is used for communicating ECU's self diagnostic signals and the results are sent to PDA monitoring system. Software on PDA is developed to monitor the ECU's self diagnostic signals using the Embedded Visual C++ compiler in which RS232 port is programmed by half duplex method. The algorithms for measuring the ECU's self diagnostic signals are verified to monitor ECU's state. At the same time, the information to fix the vehicle's problem can be shown on the developed PDA software. The possibility for remote measurement of ECU self diagnostic signal using PDA is also verified through the developed systems and algorithms.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.615-618
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• 2005

All over the world, many kinds of micro-actuators were already developed for various applications. The actuators are using various principles such as electromagnetic, piezoelectric and thermopneumatic etc. The most of the micro-actuators have been made using 2D based MEMS technology. In these actuators, it is difficult to drive 3-dimensional motion. This characteristic gives the limit of actuator application. However, micro-stereolithography technology has made it possible to fabricate freeform three-dimensional microstructures. In this technology, 2-dimensional micro-shape layer is cumulated on the other layers. This layer-by-layer process is the main principle to fabricate 3-dimensioal micro-structures. In this research, a micro-bellows actuator that is vertically moving was developed using the micro-stereolithography technology. When pressure was applied into the bellows, a non-contact actuating motion is generated. For actuation experiment, syringe pump and laser interferometer were used for applying pressure and measuring the displacement. Several hundreds micro-scale actuation was observed. And, to demonstrate the feasibility of proposed actuation principle, in this research, a micro-gripper was developed using half-bellows structure.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.778-781
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• 2002

Durability of rubber dust cover in the ball joint for automotive suspension parts were analyzed by FEM and compared with experimental data. Upper open area of ball joint is sealed by dust cover for preventing outflow of the lubricating oil and intrusion of send, dust, water, etc. This rubber cover undergoes repeated loadings such as tension and compression while the car is running. Analysis about rubber material needs to consider every kinds of nonlinearities arise in finite element analysis, which are geometric nonlinearity due to large displacement and small strain, materially nonlinearity and nonlinear boundary condition such as contact. So in the study, the deformation behavior of dust cover was analysed by using the commercial finite element program MARC. This program could solve these kinds of nonlinear analysis accurately. Finite element model of dust cover is considered as 3-dimensional half model based on 2-dimensional axisymmetric model. Material property of rubber was modeled by Ogden model and input data for calculation takes form uniaxial tension test of rubber specimen, The final object of the study is obtaining the design specification of dust covers and the result of analysis should be a useful data to design of rubber