• 한국분말재료학회지
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• 제14권6호
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• pp.410-414
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• 2007

Carbon contamination from the binder resin is an inherent problem with the metal powder injection molding process. Residual carbon in the W-Cu compacts has a strong impact on the thermal and electric properties. In this study, uncertainty was quantified to evaluate determination of carbon in a W-15%Cu MIM body by the combustition method. For a valid generalization about this evaluation, uncertainty scheme applied even to the repeatability as well as the uncertainty sources of each analyse step and quality appraisal sources. As a result, the concentration of carbon in the W-Cu part were measured as 0.062% with expanded uncertainty of 0.003% at 95% level. This evaluation example may be useful to uncertainty evaluation for other MIM products.

• Design & Manufacturing
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• 제13권3호
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• pp.24-28
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• 2019

In this study, a study was carried out that could effectively produce a heat dissipation effect on plastic materials. Using carbon nanotube (CNT), aluminum powder and plastic, the material properties were tested in 2 cases of compounding ratio. The test sample mold was designed and constructed prior to the experiment. The experiments include tensile strength, elongation rate, flexural strength, flexural elasticity rate, eye-jaw impact strength, gravity and thermal conductivity. Results from 60% and 70% mixture of aluminium to plastic were tested, and a 10% less combined result was a relatively good property. For research purposes, the heat dissipation effect and light weighting obtained a good measure when the combined amount of Al was 60%.

• Design & Manufacturing
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• 제13권3호
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• pp.6-10
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• 2019

In this study, a study was carried out that could effectively produce a heat dissipation effect on plastic materials. Using carbon nanotube (CNT), aluminum powder and plastic, the material properties were tested in 2 cases of compounding ratio. The test sample mold was designed and constructed prior to the experiment. The experiments include tensile strength, elongation rate, flexural strength, flexural elasticity rate, eye-jaw impact strength, gravity and thermal conductivity. Results from 60% and 70% mixture of aluminium to plastic were tested, and a 10% less combined result was a relatively good property. For research purposes, the heat dissipation effect and light weighting obtained a good measure when the combined amount of Al was 60%.

• 대한기계학회논문집A
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• 제35권8호
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• pp.877-882
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• 2011

스태빌라이저는 선박, 자동차 및 비행기 등에서 과도한 동요를 막고 자세를 안정시키는 장치를 말한다. 본 연구에서 스태빌라이저 링크 POM-GF25%인 복합재료와 금속을 사용하여 제조하였다. 스태빌라이저 강도 평가를 위하여 인장, 압축 및 볼스터드 빠짐으로 실시하였으며, 모두 기준을 만족하였다. 4가지 형태의 로드에서, 널링된 로드가 가장 큰 강도를 나타내었으며, 금속제를 대체할 수 있을 것으로 판단된다. 또한 사출 금형의 재해석으로 스태빌라이저 링크 본체의 형상을 개선하였다.

• 한국산학기술학회논문지
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• 제18권1호
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• pp.107-114
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• 2017

터보차저는 배기가스로 구동되는 엔진 과급기를 말하며, 배기에너지를 이용하여 배기통로에 연결된 터빈의 회전력을 변화시켜, 혼합 가스의 충전효율을 높여 출력과 연비를 향상 시키는 부품이다. 이러한 목적에 따라 과급을 조절해주는 것이 중요하며, 핵심 부품 중 노즐 슬라이드 조인트가 있다. 소재는 현재 오스테나이트 계 스테인리스강으로 높은 내열성과 내식성 등의 우수한 기계적 성질을 이용하고 있다. 그러나 절삭성이 나쁘기 때문에 절삭가공에 의해 복잡한 형상의 제품을 만드는데 어려운 점이 많다. 현재 노즐 슬라이드 조인트의 가공방법은 금속분말 사출성형후 치수정밀도를 위해 절삭가공을 행하고 있다. 따라서 본 연구에서는 Nitronic 60을 이용하여 터보차저 과급유량을 조절해주는 노즐 슬라이드 조인트의 제작 공정에서 절삭가공이 필요 없는 정형가공 공정을 제안하기 위하여, 기계적 특징에 영향과 연관이 있는 소결온도, 제품의 응력 및 변형률, 형상과 관련이 있는 모따기 펀치각도 및 펀치의 곡률반경을 설계변수로 선정하였다. 그에 따라 유한요소해석과 실험계획법인 다구찌법 및 SN비를 이용하여 가장 좋은 공정 조건을 제안하였다. 최종제품과 유한요소해석 결과의 상대밀도 및 정수압을 비교하여 경향이 일치함을 알 수 있었다. 따라서 다구찌법을 이용한 금속분말의 성형공정 설계에 유용하게 적용할 수 있을 것으로 판단된다.

• 대한치과보철학회지
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• 제43권6호
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• pp.707-716
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• 2005

Statement of problem. Collarless metal ceramic fixed partial dentures(FPDs) had an esthetic problem such as opaque reflection in cervical region. To overcome this, modified coping which removed its facial cervical metal could be used. The marginal quality could be worsen according to the amount of its facial metal reduction. Purpose. The purpose of this study was to evaluate marginal fits of collarless metal ceramic FPDs with retainers of modified copings. Material and method. Dentoform maxillary left central incisor and right lateral incisor were prepared for 3-unit collarless metal ceramic FPD and fixed in yellow stone. This model was duplicated to PBT resin dies via CAD/CAM and injection molding. Four different facial margin design groups were investigated. Group A was a coping with a thin facial metal collar, group B was a collarless coping with its facial metal to the shoulder, group C was a collarless coping with its facial metal 1 mm short of the shoulder, and group D was a collarless coping with its facial metal 2 mm short of the shoulder. Seven collarless metal ceramic FPDs per group were fabricated. They were cemented to PBT resin dies with resin cement. After removal of pontics, each retainers were separated and observed under Accura 2000 optical microscope. Then, retainers were embeded in orthodontic resin and cross sectioned faciopalatally. Internal marginal fits of midfacial porcelain margins were observed under FE-SEM. Result and conclusion. Within the limitations of this in vitro study. The following conclusions were drawn. 1. Mean marginal gaps of collarless FPDs were in the $50-60{\mu}m$ range. 2. In midfacial margin, marginal discrepancies were greater in group A than in the experimental groups(p<0.05). 3. In midpalatal margin, marginal gaps were greater in group C and D than in group A and B(p<0.05). 4. Marginal fits of porcelain margins were better than those of metal margins in collarless metal ceramic FPDs. 5. In both teeth, internal marginal gaps of group C and D were greater than those of group A and B(p<0.05).

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.25-29
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• 2019

Various process technologies for manufacturing power inductors are under development. The core goal is to increase the mixing ratio of the soft magnetic powder in the epoxy, and to uniformly disperse it in a molding-type power inductor, manufactured by the injection molding method. In this study, we investigated the effect of dispersant and silane on the dispersion of soft magnetic metal powders in epoxy. We added 0.6 wt% of dispersant and 2.0 wt% of silane, and an excellent dispersibility resulted. Under the conditions of 0.3 wt% of dispersant and 0.5 wt% of silane, we added both dispersant and silane together to observe the effect of their interaction on dispersibility. Similarly, the addition of 0.3 wt% of dispersant and 0.1 wt% of silane resulted in a sharp increase in viscosity, considered to be due to the interaction of the dispersant and silane. The addition of 0.1 wt% of dispersant with 0.5 wt% of silane resulted in a sharp rise in viscosity, and sedimentation-height decreased sharply due to the dispersion optimization.

• Journal of Mechanical Science and Technology
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• 제20권4호
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• pp.447-454
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• 2006

Hydraulic actuators are important in modern industry due to high power, fast response, and high stiffness. In recent years, hybrid actuation system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. Moreover, the hybrid actuation system has dealt with the energy consumption and noise problem existed in the conventional hydraulic system. Therefore, hybrid actuator has a wide range of application fields such as plastic injection-molding and metal forming technology, where force or pressure control is the most important technology. In this paper, the solution for force control of hybrid system is presented. However, some limitations still exist such as deterioration of the performance of transient response due to the variable environment stiffness. Therefore, intelligent switching control using Learning Vector Quantization Neural Network (LVQNN) is newly proposed in this paper in order to overcome these limitations. Experiments are carried out to evaluate the effectiveness of the proposed algorithm with large variation of stiffness of external environment. In addition, it is understood that the new system has energy saving effect even though it has almost the same response as that of valve controlled system.

• 한국건축시공학회지
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• 제1권2호
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• pp.185-190
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• 2001

The purpose of this study is the development of practical Dry floor tile unit method that settle the defect of a wet method and designed for resin mat. With use of PE resin which is confirmed the basic property, it is developed that resin mat, joint-sealing compound with fixed form and space management to Dry floor tile unit method. The result of this study is below. 1) To acquire above the 4kgf/$\textrm{cm}^2$ - construction specification criterion, the bonding space that between resin mat and tile has to occupy the 50% of resin mat module space(10,000$\textrm{cm}^2$). 2) Criteria of bonding part plane is below. simpleness of metal form. productivity, uniform quality after injection molding cooling, easy cutting for remain space management, adhesive property, construction ability, transformation of a severed piece under pressure and so on. 3) To get the shape that could protect the interfacial breakdown, it is designed that resin mat and tile are unified after the bond input. 4) Adapted joint-sealing compound is the material of urethane kinds wedge form. Resin mat has the water passageway that could drain the water. 5) To manage the severed piece of tile, the resin mat is likely to divide the half and the quarter and the plastic drainage is developed in the severed piece.

• 산업경영시스템학회지
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• 제33권4호
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• pp.159-166
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• 2010

The speed at which products are developed and released to market is tightly linked to profitability and market share. Hence, many companies are still in a desperate need of real Rapid Tooling (RT) technologies which can really help to expedite their prototype tooling and pre -production tooling for injection molding. Many other companies that have been very skeptical of RT technologies developed so far are working on Hybrid Tooling (HT) that can really meet the market standards. With the conviction that HT can be a reliable alternative for current RT technologies, this paper describes the experimentation how HT process has been being successfully established and effectively applied with typical case studies. Through the experimentation, Ceramic-filled SLA tooling was found to be aptly suited for the low grade mold, and Metal SLS tooling was found to be aptly suited for the medium volume mold both in terms of the lead time, dimensional accuracy, and tooling cost.