• 한국정밀공학회지
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• 제20권2호
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• pp.25-32
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• 2003

Molding properties of etched surface pattern are presented. Injection molding has given attention on improving dimensional accuracy and productivity. However, the molding of etched surface pattern on plastic parts is not researched relatively for its additional values, which can meet design function and customer's attraction. Specimens, whose surface patterns are made by print-type etching, are investigated. The molding properties of surface pattern are estimated with roughness deviation of surface pattern on part and mold. The etching properties are related to physical properties of plastic materials and surface roughness of etched pattern. Also, flow mark and gate location can give influence on surface pattern molding. The experimental result can contribute to good molding of surface pattern in injection molding.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.680-684
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• 1996

Welding systems cannot adapt to changes in the joint geometry which may occur due to a variety of reason. Automatic seam tracking technigue is essential to adjust the welding torch position in real time as it moves along the seam. Automatic tracking system must keep the welding speed constant unrelation to the change of the welding path. Therefore, the information from the laser displacement sensor must be converted into the input to operate the X-Y table and to rotate the desired torch position by proposed algorithm. In this research, laser displacement sensor is used as a seam finder in the automatic tracking system. X-Y moving table manipulated by ac servo motor controls the position and velocity of the torch-and-sensor part. DC motor controls the position and velocity of the torch. X-Y table controls the position of sensor and relative position of torch is controlled by dc motor which is mounted at sensor-and-torch part. Sensor is always ahead of torch to preview the weld line. From the experimental results, we could see the possiblity that the laser displacement sensor can be used as a seam finder in welding process and that the seam tracking system controlled by proposed algorithm is well done.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.281-284
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• 2006

After building a ship in a shipyard, there are so many repeated inspection of welding seam defects and painting status before delivering to the ship's owner. An inspection on the bottom part of a ship in commercial service should be done in every two years for the purpose of safety and for the prevention of ship speed deterioration. conventional welding seam inspection systems are rely on the visual inspection by human or the ultrasonic inspection for the selective part of a ship. This paper suggests a remote controlled inspection system for the examination of large ships or steel structures. The proposed system moves in contact with the ship under inspection and have a CCD camera to provide visual-guidance information to a remotely located human worker. Additionally this system utilizes a weld line tracking algorithm for an optimal position control. We verified the effectiveness of the inspection system by experimental data.

• 한국산학기술학회논문지
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• 제17권11호
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• pp.610-615
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• 2016

자동차의 부속 장비들은 용도에 따라 네비게이션, 전방 및 후방카메라, 스포일러, 선 바이저 등 다양한 것들이 채택되어 사용되고 있다. 이 중에서 선 바이저는 햇빛을 차단시켜 줌으로써 운전자의 시야 확보를 통해 안전운전을 돕는 역할을 한다. 이런 장점으로 많은 차량에 채택되어 사용되고 있는 추세이다. 그러나 대형의 플라스틱 제품들은 사출성형을 통해 생산하기까지는 웰드 라인, 충전부족, 플로우 마크, 미성형 및 변형 등 여러 가지 문제로 인한 어려움이 따른다. 본 연구는 차량용 대형 선바이저에 관한 것으로써 대형 제품을 사출 성형하는 데 발생될 수 있는 문제점을 먼저 파악하기 위해 선(先)행된 결과를 토대로 CAE 시뮬레이션을 수행하였다. 연구를 수행한 결과 첫째, 용융수지가 완전 충전되기까지 유동의 흐름을 파악할 수 있었다. 둘째, 유동선단부의 온도 편차가 $10^{\circ}C$정도로 매우 안정적임을 확인 할 수 있었다. 셋째, 성형품의 콜드 러너 취출(取出) 가능시간(약 70sec)을 구하였다. 넷째, 사출압력 및 형 체결력을 예측하여 사출 성형기의 능력을 구할 수 있었다.

• Composites Research
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• 제24권4호
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• pp.41-47
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• 2011

본 연구는 사출 성형 공정을 통하여 제작되는 단섬유강화 플라스틱 복합재료의 구조해석 기법에 관한 내용으로 소재의 이방성 기계물성을 예측하고 이를 구조해석에 적용하도록 하였다. 사출 성형 공정을 통하여 제작되는 단섬유강화 플라스틱 복합재료의 구조해석에 있어서 기존의 경우는 일반적으로 소재의 기계적 물성을 균질 등방성 탄성 모델로 이용하여 왔으나, 실제 부품 파손 모드와 크게 상이한 경우가 많다. 이러한 점을 극복하고자 사출 성형 g,름 해석, 일방향성 복합재료의 Halpin-Tsai 식과 배향 평균 모델을 도입하여 단섬유강화 플라스틱 복합재료의 섬유배향 효과가 고려되도록 새로운 구조해석 시스템을 개발하였다. 해석의 정확도는 시편시험 결과와의 비교를 통하여 검증하였으며, 섬유 배향 및 웰드라인 영향 및 섬유 함량에 따른 변화가 해석에 장 반영됨을 확인하였다. 또한 자동차 부품에 개발된 해석 시스템을 적용하여 균질 등방 모델과 달리 부품의 위치별로 다른 기계적 성능이 반영되고, 사출 게이트 위치에 따라 유리섬유 배향이 변화하여 부품의 성능이 달라짐을 확인하였다.

• Journal of Welding and Joining
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• 제15권4호
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• pp.63-69
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• 1997

Welding distortion is more serious problem than any other problems caused by welding process, especially, in the heavy-industrial place. These welding distortions are caused by nonuniform heating and cooling of metal during and after welding operations. And these distortion quantities are must be known to worker in production line because distorions are important role in assembling part. Therefore an analytical model to explain and predict the welding distortion are needed. A numerical analysis of welding distortion which is inelastic behavior of weldment would require the three dimensional calculation. But computing time and memory would be very large, and the resulting cost might be unacceptable. Therefore we use a numerical technique for two dimensional analysis in the section normal to the weld direction of weldment under an assumption of quasi-stationary conditions. But the result of the calculation under two dimensional(plane strain) assumption was not satisfied as compared with experimental result. This paper proposed a technique for analysing the welding angular distortion by using a constraint boundary condition on the two dimensional finite element model. The simulation results revealed that the constraint boundary model could more reasonably describe the welding distortion than the plane strain model did.

• 한국공작기계학회논문집
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• 제14권1호
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• pp.73-80
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• 2005

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

• 한국정밀공학회지
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• 제18권12호
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• pp.116-123
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• 2001

An automated injection molding design methodology has been developed to optimize multiple quality attributes, which are usually in conflict with each other, in injection molded parts. For the optimization, commercial CAE simulation tools and optimization techniques are integrated into the methodology. To decal with the multiple objective problem the relative closeness computed in TOPSIS(Technique for Order Preference by Similarity to Ideal Solution) is used as a performance measurement index for optimization multiple part defects. To attain robustness against process variation, Taguchi's quadratic loss function is introduced in the TOPSIS. Also, the modified complex method is used as an optimization tool to optimize objective function. The verification of the developed design methodology was carried out on simulation software with an actual model. Applied to production this methodology will be useful to companies in reducing their product development time and enhancing their product quality.

• Journal of Welding and Joining
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• 제33권1호
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• pp.35-40
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• 2015

Recently, there have been the increase of ship size and the development of oil and gas in arctic region. These trends have led to the requirements such as high strength, good toughness at low temperature and good weldability for prevent of brittle fracture at service temperature. There has been the key issue of crack arrestability in large size structure such as container ship. In this report for the first time, crack arrest toughness of thick steel plate welds was evaluated by large scale ESSO test for estimate of brittle crack arrestability in thick steel plate. For large structures using thick steel plates, fracture toughness of welded joint is an important factor to obtain structural integrity. In general, there are two kinds of design concepts based on fracture toughness: crack initiation and crack arrest. So far, when steel structures such as buildings, bridges and ships were manufactured using thick steel plates (max. 80~100mm in thickness), they had to be designed in order to avoid crack initiation, especially in welded joint. However, crack arrest design has been considered as a second line of defense and applied to limited industries like pipelines and nuclear power plants. Although welded joint is the weakest part to brittle fracture, there are few results to investigate crack arrest toughness of welded joint. In this study, brittle crack arrest designs were developed for hatch side coaming of large container ships using arrest weld, hole, and insert technology.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3280-3286
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• 2009

본 논문에서는 미세 무광부식 패턴을 갖는 HD Switch Panel 자동차 부품을 개발하는 것으로, 제품 디자인을 통해 금형을 설계, 제작하였다. 최적화된 금형 제작을 위하여 CAE(Computer Aided Engineering)해석을 통하여 사출성형 공정에서 나타날 수 있는 문제점과 부품의 수축 변형을 정량적으로 예측하였다. 그리고, 금형표면의 가열온도와 실제 금형온도를 비교함으로써 공정변수 조절을 통해 사출성형조건의 최적화도 달성할 수 있었다. 한편, 순간금형표면가열방식을 이용한 성형기술인 E-MOLD를 적용하여 자동차 내장부품용 HD Switch Panel 사출성형품을 제작하였고, 전자현미경과 원자현미경을 이용한 표면 평가 및 광택도 측정을 통하여 무광부식 패턴의 전사율 향상으로 인한 무광 특성이 향상됨(2.5이상$\to$1.5~1.7)을 확인하였다.