• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.73-80
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• 2013

This study presents sealing behavior and endurance safety of V-grooved o-rings as functions of a strain, compression stress, and contact normal stress using a FEM technique. The FEM results on the sealing behavior and endurance safety show that the maximum strain, maximum compression stress, and maximum contact normal stress of V-grooved o-rings are approximately 1.2 times higher than those of conventional solid o-rings. This is why that an o-ring has a V-groove in the center between two overlapped circles, which is very effective in sealing for ball valves, pressure vessels, and gas equipment. And the extrusion failure in V-grooved o-rings does not take place under an increased gas pressure due to a V-groove. This may extend sealing life compared with that of a conventional solid o-ring.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1513-1518
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• 1992

Numerical solution technique is suggested to analyze the vibration of a spring composed of stacked beams fastened together. Bernoulli-Euler beam theory for small deflection is used, and incremental Coulomb friction law is adopted for the interface friction. The validity of the present solution technique is checked for the perfectly bonded case and the perfect sliding case.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.11-15
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• 2009

This paper is concerned with the elastic buckling of thin-walled arches that are subjected to uniform bending. Nonlinear strain-displacement relations with the initial curvature are substituted into the second variation of the total potential energy to obtain the energy equation including initial curvature effects. The approximation for initial curvature effects that the bending normal strain distribution is linear across the cross section is applied consistently in the derivation process. The closed form solution is obtained for flexural-torsional buckling of arches under uniform bending and, it is compared with the previous theoretical results.

• Journal of Korea Multimedia Society
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• v.7 no.1
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• pp.80-90
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• 2004

Watermarking algorithm for 3D mesh model using EGI distribution of each patch is proposed. The proposed algorithm divides a 3D mesh model into 6 patches to have the robustness against the partial geometric deformation. Plus, it uses EGI distributions as the consistent factor that has the robustness against the topological deformation. To satisfy both geometric and topological deformation, the same watermark bits for each subdivided patch are embedded by changing the mesh normal vectors. Moreover, the proposed algorithm does not need not only the original mesh model but also the resampling process to extract the watermark. Experimental results verify that the proposed algorithm is imperceptible and robust against geometrical and topological attacks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.472-484
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• 2004

We proposed 3D mesh watermarking algorithm using CEGI distribution. In the proposed algorithm, we divide a 3D mesh of VRML data into 6 patches using distance measure and embed the same watermark bits into the normal vector direction of meshes that mapped into the cells of each patch that have the large magnitude of complex weight of CEGI. The watermark can be extracted based on the known center point of each patch and order information of cell. In an attacked model by affine transformation, we accomplish the realignment process before the extraction of the watermark. Experiment results exhibited the proposed algorithm is robust by extracting watermark bit for geometrical and topological deformed models.

• The Korean Journal of Rheology
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• v.9 no.2
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• pp.81-87
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• 1997

비상용성 고분자는 그 계면의 특성에 의해서 복잡한 유변학적 거동을 갖는데 그러 한 거동을 해석하기 위해서 최근에 제안된 구성방정식을 토대로 소폭 진동 전단 흐름장에서 의 유변학적 물성과 몰폴로지 전개를 예측한 바 있다. Takahashi[2]등은 이런 흐름하에서의 계면은 거의 변하지 않음을 보여주었고 따라서 이경우는 상대적으로 쉬운편이었다. 본연구 에서는 정상전단흐름장하에서의 몰폴로지 전개에 대한 구성방정식을 간단한 형태로 표현함 으로써 실제 산업계에서 이용될수 있도록 하였다. 그러한 해석을 통하여 원래의 모델에서 제시되었던 3개의 실험변수를 2개로 줄일수 있었으며 계면의 특성을 잘 나타내 주는 새로운 변수($textsc{k}$)를 도입하였다. 계면의 특성을 잘 나타내 주는 이새로운 변수를 통하여 그 계면의 영향을 예측할수 있었다. 한편 분산상의 파괴, 변형, 합체 메카니즘을 모델에 제시되었던 변 수값들을 통하여 해석하였고 이를 실험적인 데이터와 비교해 보았다.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.3
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• pp.334-341
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• 1998

This paper proposes an algorithm to obtain the time-to-contact between an observer and a target and surface orientation of the target. These two physical elements are computed from the image deformation of a known shape, which is extracted by supervised classification of detected line segments based on MAP and Mahalanobis distance. The proposed algorithm was applied to the natural outdoor traffic scene and would contribute to the development for a collision avoidance system.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.208-214
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• 1999

The purpose of this paper is to develop a profile modification technique of spur gears and its computer program for the prevention of gear tooth overlap. In the gear system, tooth overlap produces an impact at the initial contact of some tooth pairs. In this analysis, contact surface was assumed to be unbonded and frictionless under small deformation and stain. The problem is formulated by a variational statement with inequality constraint. Tooth load sharing is obtained by the application of contact theory, and overlap is known by the analysis of deformation. After carrying out the profile modification of gear tooth, we verified the reasonable results.

• Proceedings of the Korean Society of Computer Information Conference
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• 2024.01a
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• pp.371-374
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• 2024

본 논문에서는 PBD(Position-based dynamics)를 이용한 옷감 시뮬레이션에서 페이스(Face) 및 에지(Edge)의 충돌/접촉을 처리할 때 나타나는 표면 떨림 문제를 SDF(Signed Distance Field) 접근법을 통해 안정적으로 해결할 수 있는 기법을 제안한다. 충돌 제약 조건을 이용한 충돌처리에서 나타나는 옷감 시뮬레이션의 떨림 현상을 개선하기 위해 본 논문에서는 페이스 및 에지 내부에 존재하는 충돌 지점의 속도를 충돌 법선 방향과 접선 방향으로 나누어 계산하는 과정을 거치며, 그 운동량을 페이스 및 에지에 포함된 연결된 정점(Vertex)에 전달한다. 본 논문에서 제안하는 기법은 일반적인 SDF 기반 충돌 처리에서 나타나는 충돌 시 떨림 현상을 개선하며, 기존의 방법보다 안정적인 SDF 충돌처리가 가능하기 때문에 다양한 변형체 재질을 시뮬레이션 할 때 활용될 수 있다.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.348-361
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• 1991

When reinforcing strip footing on a sand 8round with reticulated root piles, reinforcing effect depends on the length , number, cross sectional area, penetration angle, spacing, and Young's modulus of piles. the mode of action of reinfocement tendons in soil isn't one of carring developed tensile stresses but of anisotropic(uni-directional) reduction or even supression of one normal strain rate. R. H. Bassett and N. C. Last proposed that the reinforcement should be located on the direction of minor strain rate which coincides with the tensile strain rate in the velocity characteristics. Based on this proposal the author carried out a series of 2 - dimentional finite element analysis which varies the parameters mentioned above.