• 한국주조공학회지
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• 제18권6호
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• pp.570-577
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• 1998

An investigation has been conducted to describe solidification characteristics in Sn-Zn binary system and Sn-Zn-Ag ternary system added by Ag produced by the continuous casting process using heated mold as a basic study for developing Pb-free solder materials. To obtain the continuous casting rods with mirror surface and near net shape at higher casting speed, water flow rates must be increased and mold temperature must be lowered. However, surface tearing in the casting rods occured at lower continuous casting speed while break out occured at higher continuous casting speed even if optimum conditions such as water flow rate and heated mold temperature are determined. Primary ${\alpha}Sn$ and eutectic structure in unidirectioally solidified Sn-Zn alloys were finer with increased casting speed. But, directionality may not be expected for primary Zn in hypereutectic Sn-Zn alloy. It was found that the addition of $0.2{\sim}0.8%$ Ag promoted the growth of primary ${\alpha}Sn$ dendrites. The changes of tensile strength and elongation in Sn-Zn binary alloys were not observed while the increase of tensile strength and the decrease of elongation in Sn-Zn-Ag ternary alloys were observed with increased casting speed.

• 대한기계학회논문집A
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• 제33권8호
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• pp.807-812
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• 2009

Most structure engineers give the casting components over-estimated factor of safety without any reasonable foundation due to the worries about the unavoidable defects such as shrinkages and porosity in castings; the engineers have little knowledge on the relation between the defect and structural behavior. And the workers in casting field also do not know how to control the defects by manufacturing; they do not know to where the defects move or until how size they reduce the defects. In this study, shrinkage defect was scanned by industrial computerized tomography instrument (CT), and subsequently was modeled to a spheroid primitive for structural analysis. Using these simplified models of shrinkage, we observed the effects of the defect on the results of the structural analysis. A commercial structural analysis code was used to do the analysis works. Considering the conclusions, it is possible to manage the shrinkages effectively in casting process and to design the products with more reliable

• 한국주조공학회지
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• 제31권5호
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• pp.243-248
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• 2011

Magnesium alloys have many advantages such as light-weight, high machinability, damping capacity, etc. So magnesium alloy parts have been used in transportation, mobile phone, military industries. Because of HCP atomic structure, Magnesium is very difficult in plastic deformation process, so most of magnesium products are fabricated by casting process. Magnesium alloys have low heat-capacity, high fluidity and low Fe solubility. For these reasons it is more suitable than aluminum in mass-production by casting. And various casting technologies have been developed. So casting technologies for magnesium developed recently is discussed in this paper.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.279-284
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• 2005

The casting defects that are caused by molten metal were cold shut formation, entrapment of air, gas, and inclusion. But the control of casting defects has been based on the experience of the foundry engineers. In this thesis, the computer simulation analyzed the flow of molten metal. The quantitative analyses which proposed the effective mold design was executed Flow patterns of 0.15-0.16m/s molten metal in 15 mm thin plate casting were investigated in order to optimize die-casting process. As increasing ingate velocity in thin plate casting, cold shot was decreased. The parameters of runner shape that affected on the optimized conditions that was calculated with simple equation were investigated. These die casting process control techniques of automobile valve body mid-plate have achieved good agreement with the experimental data of tensile strength, hardness test, and material structure photographies satisfactory results.

• 한국주조공학회지
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• 제38권1호
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• pp.9-15
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• 2018

Electromagnetic continuous casting (EMCC) was used to fabricate Ti-6Al-4V alloys with properties suitable for medical applications. Ti-6Al-4V alloy ingots fabricated by EMCC were subjected to heat treatment, such as residual stress removing (RRS), furnace cooling after solution treatment (ST-FC) and water-cooling after solution treatment (ST-WC), in order to obtain characteristics suitable for the standard. After component analysis, the microstructure and mechanical properties (tensile strength and elongation) were evaluated by ICP, gas analysis, OM, SEM, a Rockwell hardness tester and universal testing machine. The Ti-6Al-4V alloy ingot fabricated by EMCC was fabricated without segregation, and the lamellar structure was observed in the RRS and ST-FC specimens. The ST-WC specimen showed only martensite structure. As a result of evaluating the mechanical properties based on the microstructure results, we found that the water-cooled heat treatment condition after the solution treatment was most suitable for the Ti-6Al-4V ELI standard.

• 소성∙가공
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• 제26권6호
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• pp.372-377
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• 2017

In this paper, an effective design procedure was proposed to design the rib of die structure for auto-body member with ultra-high strength steel (UHSS) having ultimate tensile strength (UTS) of 1.5 GPa. From analysis results of the die structure, structural safety of the die was evaluated with information such as displacement and von-Mises stress. It was concluded that the casting part could be designed in order to reduce tool deformation. A design guideline of the die structure was proposed, especially for the rib structure in the casting part with an optimization scheme and local reinforcement concept. Simulation result following the design guideline fully explained that stability of the tool structure could be obtained simultaneously with weight minimization.

• 폴리머
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• 제34권3호
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• pp.210-214
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• 2010

트리아세틸 셀룰로오스(triacetyl cellulose, TAC) 용액필름 가공 시, 가공 공정 변수인 TAC 도프(dope)의 농도, 용매 제거 온도, 열처리 온도와 흐름특성 증가를 위하여 사용되는 가소제의 첨가가 TAC 필름의 구조 변형에 미치는 영향을 살펴보았다. 사용 도프의 농도가 높을수록, 용매 제거 온도가 높을수록 TAC의 결정화가 더 잘 발현됨을 알 수 있으며 이러한 결정화는 TAC 필름의 제조 후 열처리에 의하여 증가됨을 확인하였다. 또한, 가소제의 첨가에 의한 주사슬의 유연성 증가에 의하여 용융온도 및 결정화도가 감소하며 첨가된 가소제의 방향족 구조로 인하여 필름의 열분해 안정성이 우수해짐을 알 수 있었다.

• 동력기계공학회지
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• 제7권4호
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• pp.44-48
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• 2003

Alumium alloys casting are gaining increased acceptance in the automotive and electronic industeries and squeeze casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Al-7.0Si-0.4Mg(AC4C)alloy fabricated by squeeze casting process for development of Engine Mountain Bracket. The microstructure of squeeze casted specimen were composed of eutectic structure Alumimim solid solution and $Mg_2Si$ precipitates. The tensile strength of as-solid solution treatment Al-7.0Si-0.4Mg alloy revealed 2985MPa. It was found that Al-7.0Si-0.4Mg alloy have good aging hardening effect results are presented to show the validity of the control method.

• 대한치과의사협회지
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• 제10권12호
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• pp.809-812
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• 1972

This present paper is concerned with four unit fixed bridge construction by one piece casting technique in the case of missing of upper left second premolar and first molar. The authors had good clinical results with following advantages. 1. The complete bridge can be delivered to the patient for two appointments. 2. The laboratory procedures for solder joint are not necessary. 3. A one piece casting can be properly shaped without weak joints. 4. The casting can be heat-treated to insure an ideal molecular structure. 5. Porcelain veneers can be applied without weakening or melting solder joints.

• 한국주조공학회지
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• 제32권5호
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• pp.225-230
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• 2012

In this study, a more practical and simulation approach which can predict the mechanical properties of aluminum alloys is proposed. First, cooling rate, micro-structure, and mechanical properties of casting product were measured through casting experiment. The relation between cooling rate and SDAS decrease exponentially and the linearly decreasing relation exist between SDAS and mechanical properties. Then, the cooling rate was calculated by casting process simulation and the mechanical properties were predicted by using the relations that were derived through experiment. Experimentally measured mechanical properties and predicted values by simulation were in the range of relatively small difference. The mechanical properties of various Al alloys are expected to be predicted by the casting process simulation before actual casting.