• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.102-106
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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

• 소성∙가공
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• 제20권1호
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• pp.29-35
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• 2011

In the design of the injection molding process, various parameters including mold design parameters and molding conditions should be investigated to improve part quality. The mold temperature is one of important processing parameters that affect the flow characteristics, surface appearance, part deformation, mechanical properties, etc. Numerical analyses have been used to predict the temperature distribution of the mold under the given cooling or heating conditions. However, conventional analyses have been performed by assuming that the mold material is a single solid even though a number of plates are assembled to construct an injection mold. In the present study, a numerical approach considering the thermal contact resistance is proposed to provide more reliable prediction of the mold temperature distribution by reflecting the heat-resistance between assembled mold plates.

• Design & Manufacturing
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• 제12권1호
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• pp.31-35
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• 2018

The peltier thermoelectric module are used to cool the heat generated by electronic equipment. In order to increase the efficiency of the peltier thermoelectric module, the heat must be released to the outside. A heat sink is used to discharge such heat to the outside. in this paper, two types of heat sinks with internal tunnels were designed. And the heating and cooling performance of the heat sink with internal tunnel structure was compared and analyzed through ANSYS. The heat sink of the A type had better heat transfer than the heat sink of the B type. Which is about 70% improved.

• 산업공학
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• 제13권2호
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• pp.157-165
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• 2000

In this paper, an efficient method is proposed to place the cooling lines(CLS) and ejector pins(EPS) of mold design. The other components of mold, except CLS and EPS, can be generated automatically by batch processing. But the placements and sizes of CLS and EPS depend on the shapes of a part, so that the design works of CLS and EPS should be processed interactively. Using the pre-defined reference points, the positions of CLS and EPS can be determined interactively. By the proposed method, the interference occurred during placing CLS and EPS can be avoided, and the proper lengths of them can be calculated automatically. The information of the positions and lengths are stored in BOM database for generating a machining data. The proposed method is implemented with Unigraphics API functions and C language, tested on Unigraphics V15.

• Design & Manufacturing
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• 제2권1호
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• pp.39-43
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• 2008

There occur not only many problems in the injection process but also low quality productivity due to the injection conditions of various injection factors. 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 holding pressure affecting cooling time. Results of this study would be helpful to setting of holding pressure for optimization of forming condition in order to reduce cooling time in injection molding.

• 한국주조공학회지
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• 제41권4호
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• pp.349-356
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• 2021

우수한 기계적 성질과 가격경쟁력을 갖는 구상흑연주철 합금 개발을 위해 Cu와 Sn을 소량 첨가한 고 Mn 구상흑연주철의 응고 후 냉각조건에 따른 미세조직과 기계적 특성을 분석하였다. 첨가원소인 Cu와 Sn의 경우 펄라이트 형성 촉진을 통한 인장특성 향상을 위해 선택하였다. 또한 물성에 미치는 냉각속도의 영향을 확인하기 위해, Mg 처리된 다양한 조성의 합금을 블록시편에 주입한 후 주형 내 냉각과 800℃에서 주형 해체 후 공랭의 두 가지 냉각 조건을 비교분석하였다. 주형 내 냉각 시편의 경우, 펄라이트 분율은 27-44%, 인장강도와 연신율은 각각 513-568N/mm²와 10.4-14.3%로 나타났다. 반면, 이른 형해체 공랭 시편의 경우에는 펄라이트 분율은 77~85%, 인장강도와 연신율은 각각 728~758N/mm²와 3.2~6.0% 이었다. 결론적으로, 소량의 Cu 및 Sn 함유 Mn 구상흑연주철의 공랭 시 괄목할만한 인장강도와 연신율의 증가를 확인할 수 있었다.

• 한국기계가공학회지
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• 제18권3호
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• pp.82-87
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• 2019

Recently, plastic materials have become more diversified, and the development of materials with excellent mechanical properties and plasticity has enabled wider application, miniaturization, and refinement of injection molded products. As a result, the utilization of these products in household goods, electronics, automotive parts, and aircraft parts is increasing in almost all industries. Injection molded parts are often used externally on finished commercial products. This means that the injection mold industry is very important to the value of these products. For this reason, the industry is performing research on the precision and efficiency of the injection molding process. In this study, we investigated the applicability of the core in core cooling method to the problem of product deformation due to temperature variation in existing injection mold designs. We also characterized the cooling performance of an injection mold when using this cooling method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.73-76
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• 2004

High-temperature Superconductor(HTS) tubes were fabricated in term of different processing variables such as preheating temperature, speed of mold rotation and cooling rate by centrifugal forming method. For powder melting by induction the optimum range of melting temperatures and preheating temperature were $1050^{\circ}C{\sim}1100^{\circ}C$ and $550^{\circ}C$ for 30min, respectively. The mould roating speed was 1000rpm. A tube was annealed at $840^{\circ}C$ for 72hours in oxygen atmosphere. The plate-like grains were well developed along the roating direction and typical grain size was about more than $40{\mu}m$. It was found that Ic values increased with increasing the preheating temperature and speed of mold rotation. While Ic decreased with increasing the cooling rate. The measured Ic in $50mm{\times}70mm{\times}2.5mm$ tube was about 896Amp.

• 한국전기전자재료학회논문지
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• 제18권5호
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• pp.468-472
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• 2005

High-temperature Superconductor(HTS) tubes were fabricated in term of different processing variables such as preheating temperature, speed of mold rotation and cooling rate by centrigugal forming method. For powder melting by induction the optimum range of melting temperatures and preheating temperature were $1050{\circ}C{\sim}1100{\circ}C\;and\;550{\circ}C\;for\;30\; min$, respectively The mould roating speed was 1000 rpm. A tube was annealed at $840 {\circ}C$ for 72 hours in oxygen atmosphere. The plate-like grains were well developed along the loafing direction and typical grain size was about more than $40{\mu}$. It was found that Ic values increased with increasing the Preheating temperature and speed of mold rotation. While Ic decreased with increasing the cooling rate. The measured Ic in $50mm{\times}70mm{\times}2.5mm$ tube was about 896 Amp.

• 대한기계학회논문집
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• 제18권7호
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• pp.1818-1832
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• 1994

Transport process during solidification of an AI-CU alloy in a vertical annular mold of which inner wall is cooled is numerically simulated. A model which can take account of local density dependence on the solute concentration is established and incorperated in the analysis. Results show that thermally and solutally induced convections are developed in sequence, so that there is little interaction between them. Thermal convection effectively removes the initial superheat from the melt and vanishes as solidification proceeds from the cooling wall. On the other hand, solutal convection which is developed later over the meshy and the pure liquid regions leads to large-scale redistribution of the consituents. The degree of the initial superheating hardly affects overall solidification behavior except the early stage of the process, when the cooling rate is kept constant. Macrosegregation is reduced remarkably with increasing cooling rate, because not only the liquidus interface advances so quickly that time available for the solute transport is not enough, but also the interdendritic flow is strongly damped by rapid crystal growth within the mushy region.