• 소성∙가공
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• 제8권2호
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• pp.188-199
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• 1999

Semi-Solid Forming Process(Thixoforming, Rheocasting) is a novel forming process which has some advantages compared with conventional die casting, squeeze casting and hot/cold forging. In this study. Thixoforming process was selected as analysis processing in terms of billet handling and easiness of automation process. The Thixoforming process consists of reheating process of billet, billet handling, filling inot the die cavity and solidification of SSM part. In filling process, two rheology models which were Newtonian and Non-Nettonian model (Ostwald-deWaele)were verified with experimental results. The Ostwald-deWaele model shows the good agreement to the real flow and filling phenomena in die cavity. To give a boost the economical efficiency of Thixoforming process and to ensure the good forming result, reheating device coupled die set was proposed and the initial billet temperature for system that was found from experimental resluts. This study presents an overview of application of numerical analysis for simulation of semi-solid metal forming process to reduce the lead time for development of manufacturing part in industrial field.

• 한국수소및신에너지학회논문집
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• 제34권6호
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• pp.608-614
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• 2023

The fast filling process of high-pressure hydrogen has an important impact on the filling efficiency and safety. In this paper, a specific study is carried out on the thermophysical phenomena during the fast filling process. Starting from the gas state equation of hydrogen, the change law of the hydrogen storage temperature is obtained, and then the temperature rise prediction is constructed. The model can clarify the relationship between the filling parameters and the temperature rise during the fast filling process, thereby revealing the flow and heat transfer laws of the fast charging process. To improve the theoretical research basis for the evaluation of vehicle-mounted hydrogen fast charging capacity, temperature prediction and optimization of hydrogenation methods.

• 한국공작기계학회논문집
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• 제11권4호
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• pp.44-53
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• 2002

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis for the filling and packing phases. Molding troubles like flow mark weld line, sink ma가 short shot and warpage car be caused by these injection molding process factors. Among them the short shot was caused by the fact that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition as the flow rate for the volumetric shrinkage during the f개zen phase could not be supplied Properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing Pressure.

• Advanced Composite Materials
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• 제16권3호
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• pp.207-221
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• 2007

The filling process of resin injection/compression molding (I/CM) can be divided into injection and compression phases. During the resin injection the mold is kept only partially closed and thus a gap is present between the reinforcements and the upper mold. The gap results in preferential flow path. After the gap is filled with the resin, the compression action initiates and forces the resin to penetrate into the fiber preform. In the present study, the resin flow in the gap is simplified by using the Stokes approximation, while Darcy's law is used to calculate the flow field in the fiber mats. Results show that most of the injected resins enter into the gap during the injection phase. The resin injection time is extremely short so the duration of the filling process is determined by the final closing action of the mold cavity. Compared with resin transfer molding (RTM), I/CM process can reduce the mold filling time or injection pressure significantly.

• 한국기계가공학회지
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• 제14권5호
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• pp.36-41
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• 2015

In this paper, research on the mold design of motor housing produced by the HPDC process was conducted using computer simulations and experiments. Recently, automobile parts have been required to be light and have high strength. The die casting process was used to manufacture automotive motor housings. In the die casting process, the control of casting defects is very important. However, it has usually depended on the experience of the foundry engineer. For the analysis of the manufacturing process of motor housing, the finite element method is applied. Through the simulations using commercial software, the filling pattern and product defects could be confirmed. The analysis results obtained from the filling behavior of the casting process agreed with the experimental results. The computer simulation results of filling behavior were reflected in the optimal mold design of motor housing.

• 한국작물학회지
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• 제52권1호
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• pp.112-121
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• 2007

Grain filling is a crucial factor that determines grain yield in crops since it is the final process directly associated with crops' yield performance. Grain filling process can be characterized by the interaction of rate and duration of grain filling. This study was conducted, using 16 temperate japonica rice genotypes, with aims to (1) seek variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield, and (3) examine the influence of temperature and solar radiation for effective grain filling on grain yield in relation to grain filling duration and rate. Grain filling rate and duration exhibited highly significant variations in the ranges of $20.7{\sim}46.3\;g\;m^{-2}d^{-1}\;and\;11.2{\sim}35.5$ days, respectively, depending on rice genotypes. Grain yield on unit area basis was associated positively with grain filling duration but negatively with grain filling rate. Grain filling rate and duration were negatively correlated with each other. Final grain weight increased linearly with the rise in both cumulative mean temperature and cumulative solar radiation for effective grain filling. Higher cumulative mean temperature and cumulative solar radiation for effective grain filling were the results of longer grain filling duration, but not necessarily higher daily mean temperature and daily solar radiation for effective grain filling. Grain filling rate demonstrated an increasing tendency with the rise in daily mean temperature for effective grain filling but their relationship was not obviously clear. It was concluded that grain filling duration, which influenced cumulative mean temperature and cumulative solar radiation for effective grain filling, was the main factor that determined grain yield on unit area basis in temperate Japonica rice.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.112-118
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• 2002

Injection molding process factors such as molding temperature, injection pressure, flow rate and flow velocity, must be controlled properly in filling and packing phases in the injection molding process. In this study, effects of these factors on the injection molding were investigated through the flow analysis fur the filling and packing phases. Molding troubles like flow mark, weld line, sink mark, short shot and warpage can be caused by these injection molding process factors. Among them, the short shot was caused by that the packing pressure could not reach properly to the filling end part in the packing phase and hence the flow rate could not be supplied to the full. In addition, as the flow rate for the volumetric shrinkage during the frozen phase could not be supplied properly by the packing pressure, the short shot appeared. Here, the volumetric shrinkage reduced with increasing the packing pressure and also the warpage of molded part increased with increasing the packing pressure.

• 한국정밀공학회지
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• 제19권3호
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• pp.88-94
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• 2002

Recently, the life cycle and the lead-time of a product are to be shortened in order to satisfy consumer's demand. It is thus important to reduce the time and cost in manufacturing trial products. Several technique have been developed and successfully commercialized in the market of RPM(Rapid Prototyping and Manufacturing). However, most commercial systems currently use resins or waxes as the raw materials. So, the limited mechanical strength for functional testing is regarded as an obstacle towards broader application of rapid prototyping techniques. To overcome these problems, high-speed machining technology is being investigated worldwide for rapid manufacturing and even for direct rapid tooling application. In this paper, some fundamental experiments and analyses are carried out to obtain the filling time, materials, method, and process parameters for HisRP(High-Speed RP) process. HisRP is a new RP process that is combined high-speed machining with automatic filling. In filling process, Bi58-Sn alloy is chosen as filling material because of the properties of low-melting point, low coefficient of thermal expansion and no harm to environment. Also the use of filling wire it if advantage since it needs simple and flexible mechanism. Then the rapid product, for example a skull, is manufactured for aluminum material by HisRP process with an automatic set-up device thor 4-faces machining.

• 한국가스학회지
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• 제27권1호
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• pp.38-47
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• 2023

수소연료전지 차량 충전 과정에서, 충전소에서의 공급압력과 차량 내 저장 탱크의 압력 차이에 의해 수소가 흐르게 되고 유량은 압력 차에 의존한다. 따라서 충전 과정에서 발생하는 수소의 압력강하에 대한 고려는 필수적이며 이의 분석을 통해 수소 충전 과정의 효율성을 높일 수 있다. 본 연구에서는 충전라인 중 호스, 노즐/리셉터클, 파이프, 밸브에 대하여 압력강하를 분석하였다. 호스와 파이프는 도관에서의 압력강하로, 노즐/리셉터클은 흐름 노즐 식으로, 밸브는 기체 유량 식으로 계산하였다. 또한 각 구성요소에서 발생하는 압력강하 효과를 종합 분석한 결과 전체 충전라인에서 압력강하에 가장 큰 영향을 주는 요소는 밸브에서의 압력강하임이 밝혀졌다. 이번 연구는 추후 수소 충전을 포함한 수소 유동 해석으로 수소 충전 과정의 모델 개발에 활용될 수 있을 것이다.

• 대한기계학회논문집
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• 제17권6호
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• pp.1465-1477
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• 1993

본 연구에서는 분말혼합체의 특성인 항복응력을 포함한 Generalized Newtonian Fluid의 구성 방정식을 도입하고 미끄럼현상을 고려한 신소재의 사출성형 충전과정 해석용 CAE(computer aided engineering)시스템을 개발하였다. 수치모사를 위한 수치해석방법으로는, 유한요소법(finite element method)과 유한차분법(finite difference method)을 함께 사용하였다. 유한요소법과 검사체적법(control volume technique) 을 병용하여 유동의 진행을 수치모사 하였으며, 유한차분법을 사용하여 온도분포를 계산하였다.