• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.245-248
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• 2001

Nomura Kohsan Corp. is producing oxides, such as ZnMn$_2$O$_4$, ZnFe$_2$O$_4$, and ZnO, by burning the used dry manganese cells and by sorting out the remnant materials. It is possible to use the recycled materials of the spent dry batteries as the raw materials of deflection yoke cores. Making hish roasting temperature in the recycling system has an effect in reduction of the impurities. As a result, the loss of the cores using the recycled materials is lower. When using the recycled materials, it is required to add Mg (OH)$_2$. ZnO, and Fe$_2$O$_3$in order to rectify the composition of the MnMgZn ferrite for deflection yoke core applications. Furthermore, in order to disappear ZnMn$_2$O$_4$in the formation, it is necessary to control at higher calcining temperatures. The MnMgZn ferrite of using the recycled materials becomes Toss equivalent to the conventional material. TDK Corp. is manufacturing the deflection yoke cores from 1996 using the material recycled from the spent dry batteries.

• 동아시아경상학회지
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• 제7권4호
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• pp.1-13
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• 2019

Purpose - Based on transaction cost perspective and institution-based perspective, this research attempts to investigate the effect of outsourcing on a firm's performance and how it interacts with institutional context in which the firms operate. Research design, data, and methodology -With a sample of 164 manufacturing firms form South Korea, we examine the direct effects of outsourcing on the a firm's level of product innovation and internationalization and the moderating effects of competitive pressure and property right protection as important external factors that could affect the effectiveness of outsourcing decision. Result - The findings show that outsourcing not only enhance a firm's capability to concentrate on its core competencies, but also to increase a firm's combinative capacity to acquire external knowledge. Furthermore, we finds that in a highly competitive environment, potential knowledge spillovers to other competitors may attenuate the potential benefits of outsourcing. Conclusion - Outsourcing can enhance a firm's innovation activities by providing valuable access to external knowledge and also to complementary resources from the external partners, which in turn enables firms to focus on core competences.

• 한국정밀공학회지
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• 제22권7호
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• pp.146-154
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• 2005

Recently, the high-speed and intelligence technology of machine tools are developed for the high efficiency of productivity Under the operating condition from the high-speed of machine tools, the various failure modes can occur in core units of manufacturing system. Therefore it is for the reliability concept of machine tool to be required in a design level. And the above-stated technology must be accommodated in the feeding and spindle subsystem, etc those are the core units of machine tools. In this study, we are developed the test-bed of sliding cover (C-plate) in order to evaluating reliability and estimating failure modes of feeding subsystem under operating conditions. The reliability experiment using the developed test-bed and the additional structural analysis executed on single and double structure. We found out the weak parts of sliding cover and were able to predict a life cycle from the experiment results. In this study, we propose the new C-plate model with double link structure to apply the high-speed machine tool in the fundamental guideline.

• 한국산학기술학회논문지
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• 제5권6호
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• pp.515-520
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• 2004

코아(core) 기반의 SoC(System-on-Chip) 설계는 테스트에 관련된 많은 어려운 문제를 일으키고 있다. 그 중에서 방대한 분량의 테스트 데이터와 긴 테스트 패턴 인가시간은 SoC 테스트에서의 2가지 주요 문제로 떠오르고 있다. 많은 양의 테스트 데이터에 대한 저장공간과 인가시간을 줄이기 위한 방안으로서 테스트 벡터들의 반복되는 성질을 이용하여 최대한 효율적으로 압축하는 다양한 방법들이 제시되었다. 본 논문에서는 SoC 테스트를 위한 효율적인 테스트 데이터 압축 방법을 제안한다. 제안된 방법은 테스트 벡터 집합을 분할하고 최대한 반복되는 공통부분을 제거함으로써 테스트 데이터를 압축한다. 이 압축방법은 O(n2)의 시간복잡도를 가지며, 간단한 디코딩 하드웨어를 사용한다. 여기서 n은 테스트 벡터 수이다. 제안된 압축방법은 빠르고 쉬운 디코딩을 함께 사용하여 기존의 복잡한 소프트웨어 방식의 압축방법에 견줄만한 수준의 효율성을 보여준다.

• 한국치위생학회지
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• 제13권2호
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• pp.361-368
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• 2013

Objectives : The purpose of this in vitro study was to evaluate the effect of firing cycles on the marginal and internal fit of metal ceramic crown. Methods : Ten same cases of stone models (abutment teeth 11) were manufactured. Ten cobalt-chrome cores were made per each models and the marginal and internal fit was evaluated through a silicone replica technique. The marginal and internal fit of specimens was measured twice. The first measurement was done after manufacturing cobalt-chrome alloy core and the second measurement was done after porcelain firing. T-test of paired sample for statistical analysis was executed with SPSS 12.0K for Windows (${\alpha}$=0.05). Results : Mean(SD) marginal and internal fit were 77.1(23.3) ${\mu}m$ for the cobalt-chrome alloy core group and 84.4(21.9) ${\mu}m$ for the metal-ceramic crown group. They were statistically significant differences between groups for marginal and internal fit (p<.05). Conclusions : All metal ceramic crowns showed marginal and internal fit ranged within the current clinical recommendations.

• 한국추진공학회지
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• 제10권3호
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• pp.26-31
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• 2006

다목적실용위성 개발사업을 통해 추력기의 국산화를 성공적으로 수행하였으나 여전히 많은 추진시스템 핵심부품들에 대해서는 국산화 개발을 시도조차 하지 못하고 있는 실정이다. 향후 우주선진국으로의 진입을 위해서는 핵심부품 국산화 개발은 필수적으로 이루어져야하므로 한국항공우주연구원 다목적 위성사업단에서는 (주)한화와 더불어 상대적으로 국산화 접근의 가능성이 높은 추진제/가압제 공급용 Fill/Drain 밸브의 개발을 수행하였다. 본 논문에서는 설계, 제작 및 시험에 걸쳐 Fill/Drain 밸브 개발의 전 과정을 요약하였고, 이 과정을 통해 총 4세트의 개발모델을 국산화 하는데 성공하였으며 성능 시험을 통해 성능 요구조건을 충분히 만족함을 확인하였다.

• 한국철도학회논문집
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• 제9권1호
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• pp.43-49
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• 2006

We have evaluated the structural integrity of a sandwich composite train roof structure that can be a lightweight, cost saving solution to large structural components for rail vehicles in design stages. The sandwich composite train roof structure was 11.45 meters long and 1.76 meters wide. The finite element analysis was used to calculate the stresses, deflections and natural frequencies of the sandwich composite train roof against the weight of air-conditioned system. The 3D sandwich finite element model was introduced to examine the structural behavior of the hollow aluminum extrusion frames joined to both sides of the sandwich composite train roof. The results shown that the structural performance of the sandwich composite train roof under loading conditions specified is satisfaction and the use of aluminum reinforced frame and aluminum honeycomb core is beneficial with regard to weight saving and structural performance in comparison with steel reinforced frame and polyurethane foam core. Also, we have manufactured prototype of sandwich composite train roof structure on the basis of analysis results.

• Journal of Mechanical Science and Technology
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• 제15권11호
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• pp.1533-1540
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• 2001

A high-temperature sodium stainless steel heat pipe was fabricated and its performance has been investigated. The working fluid was sodium and it was sealed inside a straight tube container made of stainless steel. The amount of sodium occupied approximately 20% of the total volume of the heat pipe and its weight was 65.7gram. The length of a stainless steel container is 1002mm and its outside diameter is 25.4mm. Performance tests were carried out in a room air condition under a free convective environment and the measured temperatures are presented. The start-up behavior of the heat pipe from a frozen state was investigated for various heat input values between 600W and 1205W. In steady state, axial temperature distributions of a heat pipe were measured and its heat transfer rates were estimated in the range of vapor temperature from 50$0^{\circ}C$ to 63$0^{\circ}C$. It is found that there are small temperature differences in the vapor core along the axial direction of a sodium heat pipe for the high operating temperatures. But for the range of low operating temperatures there are large temperature drops along the vapor core region of a sodium heat pipe, because a small vapor pressure drop makes a large temperature drop. The transition temperature was reached more rapidly in the cases of high heat input rate for the sodium heat pipe.

• 한국IT서비스학회지
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• 제15권4호
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• pp.175-191
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• 2016

This paper investigates changing processes of new product development (NPD) systems. In order to continuously develop first-class products, world wide super-class products and hit products, R&D (Research & Development) must be competitive. Firms must achieve competitiveness in terms of quality and cost by launching new products. Most films focus on improving effectiveness and efficiency of NPD process. However, sometimes, they face to the critical challenge of transforming NPD processes entirely reflecting dramatic change of their core products. Transforming of NPD process is difficult in that it involves technological and organizational changes in marketing, R&D, Engineering and manufacturing systems. The purpose of this paper is to shed light on processes and factors affecting successful transformation of new product development systems. We present a case study on the changing processes of S company's NPD process. S company has changed new product development systems successfully from a major IT equipment supplier to an automotive supplier. Empirical results show successful changes of 10 core NPD processes from understanding the market and customers process to after sales process. In case of transformation of NPD, adaption of attribute of business is crucial for success factors in the process innovation. This paper shows the bridging the gap between IT and automotive industrial dynamics and growth through adaption of two processes in the NPD.

• Computers and Concrete
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• 제24권3호
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• pp.185-192
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• 2019

In this paper, the buckling of micro sandwich hollow circular plate is investigated with the consideration of the porous core and piezoelectric layer reinforced by functionally graded (FG)carbon nano-tube. For modeling the displacement field of sandwich hollow circular plate, the high-order shear deformation theory (HSDT) of plate and modified couple stress theory (MCST) are used. The governing differential equations of the system can be derived using the principle of minimum potential energy and Maxwell's equation that for solving these equations, the Ritz method is employed. The results of this research indicate the influence of various parameters such as porous coefficients, small length scale parameter, distribution of carbon nano-tube in piezoelectric layers and temperature on critical buckling load. The purpose of this research is to show the effect of physical parameters on the critical buckling load of micro sandwich plate and then optimize these parameters to design structures with the best efficiency. The results of this research can be used for optimization of micro-structures and manufacturing different structure in aircraft and aerospace.