• Journal of Mechanical Science and Technology
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• 제19권2호
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• pp.496-504
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• 2005

The thermal and mechanical properties of an electro-slag cast steel of a similar chemical composition with an AISI-6F2 steel are investigated and compared with a forged AISI-6F2 steel. AISI-6F2 is a hot-working tool steel. Electro-slag casting (ESC) is a method of producing ingots in a water-cooled metal mold by the heat generated in an electrically conductive slag when current passes through a consumable electrode. The ESC method provides the possibility of producing material for the high quality hot-working tools and ingots directly into a desirable shape. In the present study, the thermal and mechanical properties of yield strength, tensile strength, hardness, impact toughness, wear resistance, thermal fatigue resistance, and thermal shock resistance for electro-slag cast and forged steel are experimentally measured for both annealed and quenched and tempered heat treatment conditions. It has been found that the electro-slag cast steel has comparable thermal and mechanical properties to the forged steel.

• 한국정밀공학회지
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• 제33권8호
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• pp.661-668
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• 2016

Oil deflector prevents oil leakage that occurs in thermoelectric power plant at operating lubricant facilities. Vibration of rotating rotor-induced wear of aluminum tooth in existing oil deflector leads to oil leakage as well as life shortening of the tooth. In this study, an advanced oil deflector was developed for shock absorption and prevention of wear by decreasing clearance (from 0.5 mm to 0.2 mm) between rotor and tooth to minimize oil leakage, and by replacing 2 aluminum teeth in outmost of the oil deflector with hi-performance seal made of engineering plastic. The CFD results were compared between advanced vs. existing oil deflector to determine the amount of oil loss. Structural safety was verified through impact analyses according to the three kinds of engineering plastics, considering cost efficiency, and optimal material of hi-performance seal was chosen.

• 복식문화연구
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• 제16권5호
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• pp.910-923
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• 2008

This study investigated the difference in the influence of shopping orientations, attributes evaluation, and benefits sought on brand loyalty between Korean and American consumers within a clothing purchase context. Questionnaires were administered to 237 Korean consumers and 184 American college students who had purchase experience of casual wear in recent six months through off-line. The results were as follows. First, the hedonic shopping orientation had a positive impact on brand loyalty in both groups, whereas efficient shopping orientation had a positive impact on brand loyalty in American group. Second, the aesthetic attribute had a positive impact on brand loyalty in both groups, whereas utilitarian attribute had a positive impact on brand loyalty in Korean group. Third, brand value benefit sought had a positive impact on brand loyalty in Korean group and body expression/complement had a positive impact on brand loyalty and economic benefit sought had a negative impact on brand loyalty in American group.

• Composites Research
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• 제28권3호
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• pp.124-129
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• 2015

CNT 및 GNP 는 고강도, 고강성, 열전도율, 내부식성, 전자 차폐성 등 여러 우수한 기계적 특성을 갖기 때문에, 우주 항공분야, 전자기기 소재 및 에너지 소재에 사용되고, 제동 시 흡수 에너지가 크고 안정된 제동 효과를 나타내기 때문에 경주용 자동차나 항공기의 브레이크 디스크 재료로도 각광받고 있다. 본 연구에서는 CNT 중량비를 2 wt% 및 3 wt%, GNP 중량비를 0.5 wt%, 1 wt% 변화시켜 CF/CNT, GNP/Epoxy 복합재료를 제조하였다. 복합 재료는 기계적 방법(3-롤밀)에 의해 제조되었다. 기계적 특성은 인장, 충격 및 마모 테스트를 각각 ASTM D638, D256과 D3181에 따라 수행하였다. 시험 결과 CF/GNP0.5 wt%/Epoxy 복합재료가 인장, 충격, 마모시험에서 우수한 특성을 보였다.

• 열처리공학회지
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• 제28권4호
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• pp.181-189
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• 2015

Two types of advanced cold-work tool steels were characterized and compared. A higher-alloyed ledeburitic steel with primary carbides (denoted as 9Cr) and a lower-alloyed steel without primary carbides (5Cr) were fabricated by vacuum induction melting and subsequent hot forging. They were spheroidizing-annealed at $870^{\circ}C$, quenched at $1030^{\circ}C$ and tempered at 180 or $520^{\circ}C$. Their machinability after annealing and hardness, impact toughness, wear resistance after tempering were compared and interpreted in association with their characteristic microstructures. After annealing, 5Cr showed higher resistance to machining due to higher ductility and toughness in spite of lower strength and smaller carbide volume. Owing to smaller carbide volume fraction and the absence of coarse primary carbides, 5Cr showed even better impact toughness although the hardness was lower. The improved toughness of 5Cr resulted in excellent wear resistance, while smaller volume fraction of retained austenite also contributed to it.

• 한국정밀공학회지
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• 제27권2호
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• pp.102-108
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• 2010

Recently, carbon fiber reinforced plastic(CFRP) composite materials have been widely used in various fields of engineering because of its advanced properties. Also, CFRP composite materials offer new design flexibilities, corrosion and wear resistance, low thermal conductivity and increased fatigue life. However CFRP composite materials are susceptible to impact damage due to their lack of through-thickness reinforcement and it causes large drops in the load-carrying capacity of a structure. Therefore, the impact damage behavior and subsequently load-carrying capacity of impacted composite materials deserve careful investigation. In this study, the residual strength and impact characteristics of plain-woven CFRP composites with impact damage are investigated under axial tensile test. By using obtained residual strength and Tan-Cheng failure criterion, residual strength of CFRP laminate with arbitrary fiber angle were evaluated.

• 마케팅과학연구
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• 제14권
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• pp.59-80
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• 2004

본 연구는 패션 제품은 사회심리적 속성이 강하다는 특징을 가지고 있기 때문에 Aaker의 일반적인 제품에 적용한 브랜드 개성 차원과는 다른 차별화된 개성을 나타낼 수 있는 연구가 필요하다는 생각에서 출발하였다. 패션 브랜드 이미지에서 추출한 브랜드 개성을 나타낼 수 있는 어휘들을 포함하여, 패션 브랜드 개성 차원을 도출하여 전체적 패션브랜드 개성 차원을 밝혔으며, 또한 패션 제품의 세분화 기준중의 하나인 복종별 (정장, 캐주얼웨어, 스포츠웨어)에 따라 패션 브랜드 개성요인은 어떻게 다르게 도출되는 지를 알아보았다. 이는 패션 제품 카테고리에 맞는 패션브랜드개성 차원을 개발함으로써 차별적 브랜드 마케팅 전략 수립 및 활용을 위한 자료로 사용될 수 있다는 것에 의의를 가질 수 있다 또한 소비자들에게 있어 브랜드 개성차원의 중요성을 알아보기 위하여 각각의 개성 차원들이 브랜드의 선호도 및 구매의도에 어떠한 영향을 미치는지를 살펴보았다. 분석 결과 첫째, 패션 브랜드 개성 차원은 유행/ 혁신성, 성실성, 보편/ 안정성, 전문성의 4 가지 차원으로 도출되었다. 둘째, 복종에 따라 정장에서는 혁신/활동성, 안정성, 전문성, 보편성이, 캐주얼웨어에서는 유행/ 혁신성, 활동성, 성실성, 안정성으로, 스포츠웨어에서는 혁신성, 사교성, 성실성의 개성 차원이 도출되었다. 셋째, 패션 브랜드 개성 요인에 따라 소비자의 브랜드 선호와 구매의도의 영향력은 다르게 나타났다. 패션 브랜드 개성 차원 중에서는 성실성, 보편성, 전문성이 선호도에 유의한 영향을 미쳤고, 정장 브랜드 개성 차원 중에서는 전문성, 캐주얼웨어 브랜드 개성 차원 중에서는 활동성, 스포츠웨어 브랜드 개성 차원 중에서는 성실성이 선호도에 각각 유의한 영향을 미쳤다 또한 전반적인 패션브랜드 개성과 정장 브랜드 개성에서는 선호도와 동일한 차원들이 각각 구매의도에 유의한 영향을 미치는 것으로 나타났으며, 캐주얼웨어 브랜드 개성 차원에서는 유행/ 혁신성, 진실성, 안정성이 스포츠 브랜드 개성 차원에서는 혁신성이 각각 구매의도에 영향을 미치는 것으로 나타났다.

• 한국세라믹학회지
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• 제35권2호
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• Advances in nano research
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• 제13권1호
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• pp.97-111
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• 2022

In the present article, silica nanoparticles (SNPs) were exploited to improve the tribological and mechanical properties of vinyl ester/glass fiber composites. To the best of our knowledge, there hasn't been any prior study on the wear properties of glass fiber reinforced vinyl ester SiO₂ nanocomposites. The wear resistance is a critical concern in many industries which needs to be managed effectively to reduce high costs. To examine the influence of SNPs on the mechanical properties, seven different weight percentages of vinyl ester/nano-silica composites were initially fabricated. Afterward, based on the tensile testing results of the silica nanocomposites, four wt% of SNPs were selected to fabricate a ternary composite composed of vinyl ester/glass fiber/nano-silica using vacuum-assisted resin transfer molding. At the next stage, the tensile, three-point flexural, Charpy impact, and pin-on-disk wear tests were performed on the ternary composites. The fractured surfaces were analyzed by scanning electron microscopy (SEM) images after conducting previous tests. The most important and interesting result of this study was the development of a nanocomposite that exhibited a 52.2% decrease in the mean coefficient of friction (COF) by augmenting the SNPs, which is beneficial for the fabrication/repair of composite/steel energy pipelines as well as hydraulic and pneumatic pipe systems conveying abrasive materials. Moreover, the weight loss due to wearing the ternary composite containing one wt% of SNPs was significantly reduced by 70%. Such enhanced property of the fabricated nanocomposite may also be an important design factor for marine structures, bridges, and transportation of wind turbine blades.

• 한국철도학회논문집
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• 제9권6호
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• pp.784-791
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• 2006

This paper presents the test results to evaluate the healthiness of the ballast in subway. The test includes the dynamic load test in servicing Line the screen classification test of aggregates and the wear test. From the results, the aspect and the property of the ballast are evaluated. The dynamic load tests explain the relationship between the deterioration of the ballast and the fluctuation of loads. The assessment of impact factor based on the field test results in a good property of test blocks is proposed.