• 대한기계학회논문집A
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• 제21권11호
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• pp.1773-1785
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• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• 한국식품과학회지
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• 제24권5호
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• pp.428-439
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• 1992

고추건조에 대한 에너지사용의 효율성을 표현할 수 있는 건조효율 지표를 유도하고 정의하였으며 건조효율에 미치는 공정변수의 영향을 분석하고 carotenoids 보존의 제한조건하에서 건조효율을 최대화시키는 최적건조조건을 찾았다. 전체 사용에너지에 대한 증발에너지의 비로 단순화시켜서 열풍의 건구 및 습구온도의 함수로 표현된 건조효율이 건조공정중 실제의 에너지 사용의 효율성을 표현할 수 있는 것으로 확인되었고, 이를 이용하여 주어진 조건에서의 최적화가 가능하였다. 최적화 결과 1단계 건조에 비해서 2단계 건조가 같은 품질제한 조건하에서 건조효율을 증가시킬 수 있었다. 한편 배기공기 온도를 포함하는 간단한 변환변수와 건조되는 고추의 수분함량 사이의 관계에 의하여 건조시간 종료를 제어할 수 있는 가능성도 검토되었다. 전체적으로 본 연구에서 고추 건조시 좋은 품질을 유지하면서 건조효율을 향상시키고 에너지소비를 절감할 수 있는 건조기 운전의 방향을 제시하였다.

• 한국CDE학회논문집
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• 제9권2호
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• pp.93-101
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• 2004

In mechanical design, optimization procedures have mostly been implemented solely by CAE codes combined by optimization routine, in which the model is built, analyzed and optimized. In the complex geometries, however, CAD is indispensable tool for the efficient and accurate modeling. This paper presents a method to carry out optimization, in which CAD and CAE are used for modeling and analysis respectively and integrated in an optimization routine. Application Programming Interface (API) function is exploited to automate CAD modeling, which enables direct access to CAD. The advantage of this method is that the user can create very complex object in Parametric and automated way, which is impossible in CAE codes. Unigraphics and ANSYS are adopted as CAD and CAE tools. In ANSYS, automated analysis is done using codes made by a script language, APDL(ANSYS Parametric Design Language). Optimization is conducted by VisualDOC and IDESIGN respectively. As an illustrative example, a mold design problem is studied, which is to minimize temperature deviation over a diagonal line of the surface of the mold in contact with hot glass.

• 시스템엔지니어링워크숍
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• 통권4호
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• pp.1-4
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• 2004

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.159-160
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• 2015

Recently, it is increased to use the portable device with small size. It is also increasing for demand of a small size adapter. To reduce the size of components, switching frequency has to be increased. But it causes higher switching loss and temperature of components. Especially, the temperature of adapter must be limited because adapter can be easily touched when portable device is being charged. To reduce temperature of adapter, high efficiency is essential. To solve this problem, this paper proposes design of resonance frequency optimization for LLC converter with high efficiency and low temperature of passive components.

• 소성∙가공
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• 제13권5호
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• pp.449-454
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• 2004

The annealing behavior of a 5083 Al alloy deformed at cryogenic temperature was investigated, focusing on the evolution of microstructures and mechanical properties. Especially, the effects of annealing temperature, $150~300^{\circ}C$, and time, 3∼60min., on microstructures and mechanical properties of the sheets received 85% reduction at cryogenic temperature were investigated. The optimization of the annealing conditions resulted in a mixture of equiaxed grains and elongated subgrains, exhibiting a good combination of uniform elongation and high strength.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.51-52
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• 2008

• 대한기계학회논문집B
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• 제33권6호
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• pp.403-410
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• 2009

This paper proposes a new approach to find the optimum ratios between sizes of the heat exchangers of the heat recovery steam generator (HRSG) system with limited size to maximize the efficiency of the steam turbine (bottom) cycle of combined cycle power plants (CCPP), but without performing the bottom cycle analysis. This could be achieved by minimizing the unavailable exergy (the sum of the destroyed and the lost exergies) resulted from the heat transfer process of the HRSG system. The present approach is relatively simple and straightforward because the process of the trial-and-error method, typical in performing the bottom cycle analysis for the system optimization, could be avoided. To demonstrate the usefulness of the present method, a single-stage HRSG system was chosen and the optimum evaporation temperature was obtained corresponding to the condition of the maximum useful work. The results show that the optimum evaporation temperature based on the present exergy analysis appears similar to that based on the bottom cycle analysis. Also shown is the dependency of size (NTU) ratios between the heat exchangers on the inlet gas temperature, which is another important factor in determining the optimum condition once overall size of the heat recovery steam generator is given. The present approach turned out to be a useful tool for optimization of the singlestage HRSG systems and can easily be extended to multi-stage systems.

• 한국가스학회지
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• 제16권1호
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• pp.26-32
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• 2012

화학물질의 화재위험을 나타내는 가장 중요한 물성의 하나인 자연발화점의 실험 데이터는 그 필요에도 불구하고 데이터를 얻는 것이 어려운 경우가 많다. 이 연구에서는 DIPPR 801에서 얻은 503개 유기물의 자연발화점 실험데이터로부터 자연발화점을 예측하는 부분최소자승법(PLS) 및 support vector machine(SVM) 모델을 만들고 비교하였다. 그룹기여법을 이용하여 59개 작용기가 이 예측모델의 독립변수가 되었다. 두 모델에서 결정해야 할 매개변수는 교차검증으로 계산된 오차를 이용하여 결정되었고, SVM모델은 그 매개변수가 많아 particle swarm optimization을 이용한 최적화를 이용하였다. 전체 데이터에 대해 계산된 평균절대오차는 PLS가 58.59K였고, SVM이 29.11K여서 SVM이 PLS에 비해 매우 우수한 예측성능을 보였다.

• 한국식품과학회지
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• 제21권5호
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• pp.655-661
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• 1989

고추건조에 있어서 품질의 최적화를 위한 최적건조 공기온도와 상대습도를 수학적 최적화기법에 의하여 찾았다. 얻어진 최적 건조조건을 품질변화 kinetics와 제어변수가 상태변수의 변화에 미치는 영향을 관점에서 분석하였다. Carotenoids의 보존과 갈변억제를 위한 최적 건조조건은 거의 일치하였다. 2단계 건조의 최적 조건은 상대습도는 약 10%의 하한값을 취하면서 첫 번째 단계 건조에서 50%의 하한온도를 취하고 두 번째 단계 건조에서는 고온으로 증가하였다. 두 번째 단계 건조온도와 단계 이동시간은 전체건조 소요시간에 따라 달랐다. 제어변수가 시간에 대해 일정한 경우의 고추건조를 반응표면 분석에 의하여 제어변수의 영향을 살펴볼 때 최적점이 하한의 상대습도에서 목적건조 수분함량 0.2(건물기준)를 얻을 수 있는 가장 낮은 건조온도로 결정됨이 확인되었다. 2단계 건조는 건조 소요시간이 비교적 짧을 때 3-5%의 목적함수 개선의 효과가 있었다.