• The Journal of the Convergence on Culture Technology
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• v.4 no.3
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• pp.209-212
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• 2018

Anisotropic conductive film(ACF) bonding is widely used for making fine interconnections between two different materials where soldering is not easily applicable. There are three constraints for the successful implementation of ACF bonding. A bonding contact should be pressed by a hot head with the right pressure and temperature for a pre-defined curing time. In this paper, a method for ACF bonding based on machine vision system is proposed and verified through some experiments. The system calculates the position and orientation of printed circuit boards(PCBs) on a bonding table and estimates the optimal hitting point where the hot head should be applied. Experimental results show that the proposed system achieves better adhesive strength by providing head flatness over contact surfaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.4715-4720
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• 2010

In this study, we developed new tapered rolling type strip pressure key for the prevention of scratch in sheet metal forming line. The developed pressure key is equipped with two tapered rollers inside a conventional block pressure key. Through the scratch test, for the case of transversal movement the tapered rolling type pressure key reduces both friction and depth of scratch by the effect of tapered shape which decreases the pressure spike on edge, and for longitudinal movement the scratch on the sheet metal surface is certainly removed by the rolling contact.

• Tribology and Lubricants
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• v.25 no.5
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• pp.335-341
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• 2009

Elastohydrodynamic lubrication (EHL) analysis shows that film thickness is very flat in the contact area and pressure distribution is somehow similar to that of Hertzian contact pressure except the outlet region with pressure spike. These typical patterns of EHL film thickness and pressure are the cases under the steady contact conditions of applied loads and speeds. However, many engineering contacts are rather under the conditions of varying loads and contact speeds, and therefore the predictions for endurance life and performance of machine elements with steady EHL analysis are not suitable in many occasions. This study shows the differences in film thickness formation and pressure distribution between steady and transient contact conditions in several contact cases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.15-24
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• 1996

로켓모타의 연소관은 구조적인 편의성 및 경량화를 위하여 도옴-실린더부와 실린더-노즐부에 나사체결방법을 많이 적용하고 있는데, 나사의 골부위에 집중응력이 발생하여 인장강도를 넘는 응력이 발생하는 경우가 있다. 본 연구에서는 나사의 골부위의 응력수준을 좀 더 정확히 예측하기 위하여 나사체결시 작용하는 조립 토오크에 의한 초기하중을 고려한 구조해석을 수행하였으며, 나사부위에 발생하는 응력이 항복강도를 초과하므로 정확한 해석을 위하여 탄소성해석을 수행하였다. 조립 토오크에 의한 초기하중은 나사체결 멈춤부에 음(-)의 접촉 간극을 부여하여 모델링하였으며, 조립 토오크의 크기는 나사체결 근접부에서 변형률을 측정하여 모사하였다. 해석결과 초기하중을 고려하여 구조해석을 수행하면 최대예상 작동압력에서 초기하중의 영향은 거의 나타나지 않았으며, 마찰계수를 감소시키면 최대응력이 감소하여 구조적 안전성이 증가할 것으로 판단된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2670-2677
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• 2002

The ring rolling process involves three-dimensional non-steady material flow and continuous change of radius and thickness of the ring workpiece. In this study, the deformation analysis and geometric updating algorithm of the ring rolling process were verified by using the three-dimensional rigid-plastic finite element method. Manufacturing processes for plain ring and T-shaped ring were investigated by comparing experiments with simulation results, especially in side spread, load-stroke and pressure distribution, showing a good agreement. It was concluded that the simulation method would be a useful tool for the design of a ring rolling process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.68-72
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• 1992

자동차 및 각종 판재 성형시 성형율을 향상시키는 방법에는 신소재 개발, 금형기술개발, 접촉부의 마찰을 줄여 주기 위한 윤활 등등이 있겠으나 손쉽게 공구다이 상하에 비드를 설치하여 판재를 성형할 경우 미끄럼 저항의 균형을 이루어 주름 억제와 두께분포가 보다 균일해지며 스프링백 현상 등으로 인한 성형 후 치수 불량 등을 주어 판재성형율을 향상시키는데 기여할 수 있다. 본 연구에서는 펀치가 판재를 성형하기 위해 진행됨에 따라 공구다이와 펀치간의 접촉각도가 변하게 되는 점을 고려하여 인출 각도변화에 따른 인출특성 및 마찰계수 변화등을 알아보고자 하며 원형 형태의 환저비드, 단일원형비드, 이중원형 비드의 종류와 크기변화 및 비드좌우 모서리 변화, 공구다이모서리변화, 블랭크가압력 변화, 비드 전진깊이 변화, 비드통 과 후 재료의 기계적 성질 변화등 인출 특성에 영향을 미치는 인자들을 변화시켜나가며 이에 따르는 인출특성을 Data Bank화 시켜 비드 종류나 형상에 따른 금형설계의 기초자료를 제공하고자 한다.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.122-128
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• 1999

Bolted joint assembly for nuclear power plants consists of various components : cover plate, retainer plate, manway flange, gasket and stud bolts/nuts. To guarantee the soundness of the joint, it is important to prevent leakage through the gasket and reduce the stress concentration factor at the thread root. In this paper, Submodeling technique for the finite element method is proposed to accurately compute three dimensional contact stresses which govern the sealing performance and the maximum contact stresses at the threads root. For verification of global solutions used as boundary conditions of submodel solution, the stresses on the cover plate and the manway flange are measured by strain gages when internal pressure is applied to the bolted joint assembly. The numerical results are compared with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.194-194
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• 2004

개인용 로봇의 촉각기능을 담당할 수 있는 유연성 기반 인공피부센서 시스템을 설계 및 제작하였다. 수직력을 측정할 수 있는 64 개의 FSR 센서(Techstorm Co.)와 전단력을 동시에 측정할 수 있는 1 개의 PVDF 필름(PSI Co.)을 융합하여 인공피부센서 시스템을 제작하였다 제작된 촉각센서는 10 cm x 10 cm 크기로 임의의 물체가 접촉할 경우 형상을 측정할 수 있으며 또한 물체표면의 거칠기 상태를 판단할 수 있다. 한편, 3축 로드셀 기반 평가 시스템을 제작하여 센서의 수직력을 평가하였으며 PVDF 필름을 통한 접촉하는 대상의 거칠기 평가는 주파수 분석으로 평가하였다.(중략)

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.51-57
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• 2006

The contact pressure distribution between a rubber wiper blade and a glass windshield is a major factor for wiping performance. A modeling and simulation method has been developed to forecast the contact pressure distribution on a wiper blade. For modeling multi-body dynamics of an wiper linkage system and flexible nature of wiper blade, ADAMS and ADAMS/flex are employed. A simulation study has been also conducted to obtain contact pressure distribution. Comparison between simulation and measurement is provided to ensure fidelity of the model and the simulation method.

• Journal of the Korean Society of Safety
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• v.5 no.3
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• pp.8-26
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• 1990

It is important to have exact information about the contact pressure distribution in the design of connected parts of machines and structures. In previous works, stress analyses on a two body contact problem have been carried out in large numbers. Besides, the measurement of contact stress is important to confirm the adequateness of the theoretical analysis, to verify appropriateness of Hertzian contact theory and to know the practical pressure distribution, but an excellent measuring method con't be found at present. Therefore, a quantitative measurement of contact pressure by means of ultrasonic waves using a normal probe and an angle has been proposed to measure the contact pressure distribution between two rough flat surfaces. At first, in a new proposed calibration method, the relation between mean contact pressure and sound pressure of reflected waves is obtained by using calibration blocks with various surface roughnesses made of the same material as the rectangular section beams And then, this experimental results are compared with the analytical ones, and the utility of this method is discussed.