• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5737-5742
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• 2015

Insert injection molding is a process in which molten plastic is injected into a mold that contains a pre-placed insert. During the injection stage, the insert can be deformed by the pressure applied by the polymer melts. The deformation of the insert changes the width of the flow path around the insert, which can cause several defects such as short shots or warpages of the parts. In order to reduce the deformation of the insert, it is important to achieve successful design of gating system, insert geometry, and molding conditions. In the present study, the insert deformations that occured during the injection molding of the BLDC motor stator were investigated by numerical analyses. The gate location and the insert shape were modified to reduce the insert deformation. Finally, the injection molding with the modified designs was carried out, and it was confirmed that the insert deformation was reduced.

• Composites Research
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• v.35 no.3
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• pp.196-200
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• 2022

Split Hopkinson Pressure Bar (SHPB) is a general test equipment for measuring the mechanical properties of high modulus metal and composite materials at high strain rate. However, for the soft plastic material, it is difficult to hold the specimen and achieve dynamic stress equilibrium due to the weak transmitted signals. In this study, SHPB test apparatus were designed to measure accurately the high strain rate stress-strain curve of the soft plastic materials by changing the incident bar materials and the shape of the specimen holder parts. In addition, to verify the high strain-rate tensile strain data obtained from SHPB, the strain distribution of the specimen was measured and analyzed with a high-speed camera and the digital image correlation (DIC), which was compared with the strain history measured from SHPB.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.86-94
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• 2023

In this study, a supplementary detail capable of restraining out-of-plane deformation was proposed for steel slit dampers, and a constant amplitude cyclic loading test was performed with the application of the proposed detail and the shape ratio of the damper as variables. Repeated hysteresis and cumulative plastic deformation according to the test results were analyzed. Repeated hysteresis of the slit damper with the proposed detail showed a stable spindle-shaped hysteresis within the set variable range, and no out-of-plane deformation of the damper was observed until ultimate state. It was confirmed that the restraining panel effect through the application of the proposed details is effective in terms of both the strength and deformation capacity of the damper. In addition, experimental parameters for the fatigue curve evaluation of slit dampers were derived in this study. Based on the results, it is judged that quantitative comparison of structural performance with various types of seismic devices will be possible in the future.

• Journal of the Korea Computer Graphics Society
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• v.10 no.4
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• pp.27-36
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• 2004

본 논문에서는 뇌의 하부구조인 해마를 정확하게 분석하기 위한 형상 정규화 방법과 정상인과 간질 환자의 해마를 분류하기 위한 방법을 제시한다. 해마에 대한 형상 분석 과정은 크게 형상 표현을 구축하는 과정, 형상의 유사도를 측정하는 과정, 정상인 집단과 환자 집단을 분류하는 과정으로 이루어진다. 본 연구에서는 해마의 형상 표현으로 메쉬, 골격, 복셀로 이루어진 하이브리드 옥트리 자료구조를 구축하였다. 또한 Iterative Closest Point (ICP) 알고리즘을 사용하여 해마 골격을 기반으로 한 정규화를 수행하였다. 그리고 정규화된 해마 형상을 전역적, 국부적으로 분석하여 최종적으로 입력된 해마가 정상인 또는 간질 환자에 속하는지를 학습된 데이터를 이용하여 분류하였다. 본 논문에서 제시한 ICP 기반의 정규화 방법은 3차원 해마 형상을 정확하게 분석하게 해주고, 골격의 정점 수를 조절함으로써 정규화 시간을 감소시킬 수 있다. 뿐만 아니라 3차원 해마 모델의 형상을 신경망을 통하여 학습시킴으로써 해마의 형상이 변형된 환자 집단과 정상인 집단을 분류하는데 이용할 수 있다.

• Journal of the Korea Computer Graphics Society
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• v.8 no.4
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• pp.1-7
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• 2002

This paper presents a new approach for modeling human limbs shape from 3D scan data. Based on the cylindrical structure of limbs, the overall shape is approximated with a set of ellipsoids through ellipsoid fitting and interpolation of fit-ellipsoids. Then, the smooth domain surface representing the coarse shape is generated as the envelope surface of ellipsoidal sweep, and the fine details are reconstructed by constructing parametric displacement function on the domain surface. For fast calculation, the envelope surface is approximated with ellipse sweep surface, and points on the reconstructed surface are mapped onto the corresponding ellipsoid. We demonstrate the effectiveness of our approach for skeleton-driven body deformation.

• Science of Emotion and Sensibility
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• v.14 no.1
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• pp.117-126
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• 2011

This study investigates the physical properties and manufacturing method of shape memory fabric for emotional garment made by polypropylene. For this purpose, polypropylene(PP) POY and SDY were texturized using low temperature and constant length heat treatment texturing technologies, respectively. The shape memory fabrics made using these texturized PP yarns were woven with two kinds of PET and PTT shape memory yarns on the air-jet loom and the various physical properties of four kinds of shape memory fabrics were measured and discussed. The tenacity and breaking strain of PP texturized yarns treated by low temperature and constant length heat treatment showed high weaving efficiency and the wet thermal shrinkage of PP textured yarns was shown less than 1.5%, dry thermal shrinkage was ranged between 3% and 5%, which means thermal stability compared to the PTT textured yarn with high thermal shrinkage, 5~8%. The shape memory characteristics of PP shape memory fabrics measured by Toray method showed five grade as same value as PTT shape memory fabric. The heat keeping property of the PP shape memory fabric showed 56% higher value than that of PTT shape memory fabric. The water repellency of PP shape memory fabric measured by spray method showed five grade as same value as PTT shape memory fabric treated with water repellent agent. Especially, shape memory properties of PP shape memory fabric measured by 3-D image and camera measurement methods showed similar characteristics to the PTT shape memory fabric.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.45-51
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• 1995

자동차 엔진의 피스톤은 핀 구멍의 복잡한 형상과 2사이클 엔진의 경우 실린더쪽 흡기 및 배기 포트의 위치에 따라 균일하지 않은 열이나 응력 등의 영향에 의한 변형을 고려하여, 상온에서의 형상이 각종 평가 시험을 거쳐 엔진마다 다양한 형상을 갖는 피스톤으로 결정된다. 본 연구에서는 컴퓨터 제어에 의한 방법으로서 타원형상을 갖는 임의의 피스톤을 고속, 고정도로 가공할 수 있는 CNC(Computer Numerical Control)선반 개발에 관하여 연구 하였다. 피스톤 데이터를 퍼스널 컴퓨터로 입력하고 CNC 제어하므로 마스터캠의 제작 불필요, Recess 등과 같은 미세가공 가능, 피스톤의 형상변경 용이, 고속가공 등으로 모방절삭 방식보다 훨씬 높은 생산성 향상이 기대된다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.508-511
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• 2010

본 논문에서는 정상상태 유체-구조 연성문제를 연속체 기반으로 정식화하고 유한요소법을 이용하여 완전 연성된 해를 구하였다. 대 변형을 고려하기 위하여 토탈 라그란지안 정식화를 사용하였으며 유체 및 구조의 비선형성이 고려되었다. 유체와 구조 영역의 형상을 NURBS 곡면을 이용하여 매개화하여 표현하였으며, 형상 최적화를 위해 효율적인 설계민감도 해석법인 애조인 기법을 이용하여 압력, 속도, 변위 등에 대한 설계민감도를 구하였다. 이를 이용하여 최소 컴플라이언스를 갖게 하는 구조물 내부의 유체영역의 설계 등의 수치예제를 통하여 개발된 방법론의 타당성을 확인하였다.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.27-38
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• 2010

A series of model test as well as numerical analysis by FEM was performed to investigate lateral earth pressure acting on a buried pipe in soft ground undergoing horizontal soil movement. A model test apparatus was manufactured so as to simulate horizontal soil movement in model soft ground, in which a model rigid buried pipe was installed. The velocity of soil deformation could be controlled as wanted during testing. The model test was performed on buried pipes with various diameters and shapes to investigate major factors affected the lateral earth pressure. The result of model tests showed that the larger lateral earth pressure acted on the buried pipes under the faster velocity of soil movement. The result of numerical analysis, which was performed under immediate loading condition, showed a similar behavior with the result of model tests under 0.3mm/min to 1.0mm/min velocity of soil deformation. Most of model tests showed the soil deformation-lateral load behavior, in which the first yielding load developed at small soil deformation and elastic behavior was observed by the yielding load. Then, lateral load was kept constant by the second yielding load, in which plastic behavior was observed between the first yielding load and the second yielding one. Beyond the second yielding load, the compression behavior zone was observed. When the velocity was too fast, however, the lateral load was increased with soil deformation beyond the first yielding load without showing the second yielding load. The buried pipes with the larger diameter was subjected to the larger lateral load and the larger increasing rate of lateral load. At small soil deformation, the influence of diameter and shape of buried pipes on lateral load was small. However, when soil deformation was increased considerably, the influence became more and more.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.1
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• pp.171-180
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• 2001

Collision accident reconstruction algorithm are developed based on the deformation shape and severity of a car body. At first, the body stiffness equation representing the force-deformation relationship is derived using finite element analysis for head on collision of two cars. The database of deformation shapes and energies is constructed for five different collision configurations; each configuration contains three velocity conditions. Deformation shapes are obtained using a curve fitting method and result in cubic polynomials. Deformation energies are calculated using a stiffness equation and deformation data. Three algorithms are developed to reconstruct collision configuration compared with constructed database. The developed algorithms show reasonably good performance to find collisions conditions for some test problems.