• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.865-870
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• 2004

This paper describes the generation of chordal surface for various shell structures, such as automobile bodies, plastic injection mold components and shell metal parts. After one-layered tetrahedral mesh is generated by an advancing front algorithm, the chordal surface is generated by cutting a tetrahedral element. It is generated one or two elements at a tetrahedral element and the chordal surface is composed with triangular or quadrilateral elements. This algorithm has been tested on several models with rib structure.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2355-2363
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• 2002

The accompanying paper, Part 1, has presented the physical modeling and basic numerical analysis results of both the flow-induced and thermally-induced residual stress and birefringence in injection molded center gated disks. The present paper, Part II, has attempted to investigate the effects of various processing conditions of injection/compression molding process on the residual stress and birefringence. The birefringence is significantly affected by injection melt temperature, packing pressure and packing time. Birefringence in the shell layer increases as melt temperature gets lower. The inner peak of birefringence increases with packing time and packing pressure. On the other hand, packing pressure, packing time and mold wall temperature affect the thermally-induced residual stress rather significantly in the shell layer, but insignificantly in the core region. Injection/compression molding has been found to reduce the birefringence in comparison with the conventional injection molding process. In particular, mold closing velocity and initial opening thickness in the compression stage of injection/compression molding process have significant effect on the flow-induced birefringence, but not on tile thermal residual stress and the thermally induced birefringence.

• 한국주조공학회지
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• 제29권5호
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• pp.204-212
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• 2009

The effects of addition of magnesium only and the simultaneous addition of magnesium and aluminum on the graphite morphology of the cast iron with the composition of 3.6wt.% and 2.5wt.%Si poured into shell stack mold were investigated. The nodularity and mechanical properties of the specimen with smaller cross-section were higher than those with langer one, when copper was not added. When the magnesium only was added, the nodularity was decreased with decreased residual magnesium content and the C. V, graphite was obtained with the magnesium content in the range of 0.010~0.015wt.%. When the magnesium and aluminum were added together, the nodularity was decreased with decreased residual magnesium and increased aluminum contents. When copper was added, the volume fraction of pearlite in the matrix, strength and hardness were higher and elongation was lower for specimen with smaller cross-section. The volume fraction of pearlite, strength and hardness were increased and the elongation was decreased with increased copper content for the specimen with C, V, graphite.

• Design & Manufacturing
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• 제6권1호
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• pp.12-17
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• 2012

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, a full-3d simulation based on solid elements has been reported as a reliable approach. The present work covers three-dimensional injection molding simulation and relevant deformation analysis of an injection molded plastic lens based on 3d solid elements. Numerical analyses have been applied to the injection molding processes of three aspheric lenses for an image sensing module of a mobile phone. The reliability of the proposed approach has been verified in comparison with the experimental results.

• 대한기계학회논문집A
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• 제23권11호
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• pp.2087-2095
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• 1999

One of the main causes of unwanted dimensional changes in precision metal mold casting parts is excessive and irregular residual stresses induced by temperature gradients and plastic deformation in the solidifying shell. Residual stresses can also cause stress cracking, and lower the fatigue life and fracture strength of the casting parts. In the present study, aluminum alloy casting system with metal mold equipped with electrical heating elements and water cooling units was designed and the casting specimens were produced to quantify the effects of different cooling conditions on the development of residual stresses. The layer removal method was used to measure the biaxial residual stresses in casting specimens produced from the experiments. The experimental results agreed with Tien-Richmond's theoretical model for thermal stress development for the solidifying metal plate.

• 동력기계공학회지
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• 제18권3호
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• pp.51-58
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• 2014

Injection molding simulation provided optimized design results by analyzing quality problems while the product is in assembly or in the process of manufacturing with make automobile plastics. Frequent change of design, change of injection molding, repetition of test injection which was held in the old way can now be stopped. And quality upgrade is expected instead. This report deals with the effect which the position of injection molding automobile console gate and number has on product quality including pressure at end of fill, bulk temperature at end of fill, shear stress of end of fill, residual stress at post filling end, product weld lines and warpage results. Simpoe-Mold simulates the complete manufacturing process of plastic injected parts, from filling to warpage. Simpoe-Mold users, whether they are product designers, mold makers or part manufacturers, can identify early into the design stage potential manufacturing problems, study alternative solutions and directly assess the impact of such part modification, whatever the complexity and geometry of such parts, shell part as plain solid parts.

• 대한기계학회논문집A
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• 제34권7호
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• pp.919-928
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• 2010

연속주조 시에 폭변경 속도를 향상시키기 위해 폭조정의 4 가지 패턴에 대해 연구하였다. 주요 사항은 폭변경 장치의 구동력을 최소화하고, 몰드 내의 응고막의 변형해석 모델을 개발하고, 폭변경 속도 상승을 제한하는 주요인자를 도출하는 것이다. 폭변경 실험을 근간으로 4 개 패턴의 주요 특징을 도출하였고, 각 패턴에 대한 힘을 비교하였다. 실험은 각 패턴의 구동력 비교를 위해 동일한 주조속도에서 수행하였다. 응고막변형 해석모델의 변수를 조정하기 위해 실험결과를 모델에 적용하였다. 폭변경 속도를 상승시키고, 구동력을 저감시키기 위해 패턴의 변수를 제어하였다. 가장 효율적인 패턴은 고속패턴이었으며, 구동력을 저감하기 위한 주요인자는 구동장치가 이동할 때의 기울기였다.

• 한국의류산업학회지
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• 제6권5호
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• pp.648-654
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• 2004

The purpose of this study was to develops of brassiere pattern for middle school students (15 ages ${\mp}$ 3). In order to design a brassiere pattern, the body surface shell was used as the basic pattern. The foundation pattern and the four-piece brassiere pattern with wire were designed and sewed. The results of this study can be summarized as follows. 1. The foundation pattern of the size 75A was proved proper for the body by the wearing tests. Each angle and length of the parts on the base line of the breasts played an important role on setting the pattern. 2. As based on the body surface shell extracted from a plaster mold, the cups of brassiere pattern were applied to the body surface shell, and full side stretch -wings were applied to 8% reduced body size. 3. As the result of the wearing test, the excellence of the experimental brassiere was recognized objectively, with high marks in all the items of clothing compensation, body motion, clothing pressure and breasts growth. The experimental brassiere was covering the whole breasts to cope with change according to breasts growth, It was designed to support the breasts firmly, not to press the middle part of them. Simultaneously, this has the advantages that satisfy a characteristic of a figure and the purpose of putting it on.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2012년도 춘계학술논문집 2부
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• pp.781-784
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• 2012

본 논문은 하이브리드 자동차 및 전기자동차의 고주파 발생시 전자파를 차단하는 역할을 하는 인버터 실드쉘의 프로그레시브 금형의 스트립 레이아웃과 금형설계 및 제작에 관한 연구이다. 총 11공정으로 블랭크 레이아웃을 구성하였고, 3D 금형설계를 하였다. 이와 같이 제작한 금형을 2차에 의한 트라이아웃을 하여 일본에서 수입하던 단발 금형을 프로그레시브 금형으로 인버터 실드쉘을 양산하여 원가절감, 생산성 향상에 기여하였다.

• Design & Manufacturing
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• 제13권4호
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• pp.28-33
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• 2019

In this study, the flow analysis of fermentation tank, digester and dryer, which are the main equipment in environmental energy facilities, was carried out. Numerical analysis was carried out with the size of the actual plant, and 3D modeling program CATIA V5 R16, grid generation program Gambit, and general purpose flow analysis package ANSYS-FLUENT (v13) were used. Simulation results of the carrier gas flow analysis in the STD dryer using the computational fluid dynamics program showed that the carrier gas smoothly circulated between the shells of the dryer and the flow was uniformly distributed without stagnation or flow. It is also predicted that rotational flow due to shell rotation is active. The average flow velocity of carrier gas in the STD dryer was estimated to be about 0.196m / s, and the average temperature of the carrier gas was calculated to be 424K. Due to the relatively slow carrier gas velocity and high average temperature, the water content of the sludge can be effectively lowered.