• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.2
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• pp.185-189
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• 2016

Energy-saving heat depending on the country's rise in oil prices up to the product development is regarded as pending issues. Therefore, in recent years, been a continuing research studies developed for increasing the economic efficiency and reliability achieved in effectively using the side of the energy for heating using electrical to address these problems and, in particular made active the technology developed for high performance and renal material becoming. This paper is to study the development of highly efficient induction heating device according to the excellent heat transfer characteristics for energy transfer. Induction heating is used as the phenomenon of electromagnetic induction, such as heat transfer conduction or convection of the existing methods are no different. Medium heat without beating is absorbed directly into the water column switched rapidly, have features that heats evenly. In addition, high-frequency induction heating in a variety of frame designs. Heating element heats only when utilized properly, it is possible to heat the focus.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.136.1-136.1
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• 2010

고체산화물 연료전지(SOFC)에서 사용되는 연결재의 주 기능은 각 단위 셀의 연료극과 다음 셀의 공기극을 전기적으로 연결하여, 공기와 사용연료의 분리역할을 하기위해 사용된다. SOFC용 연결재는 다른 구성요소 소재보다 높은 전기전도성, 낮은 이온전도성이 요구되며 SOFC는 고온에서 작동되기 때문에 다른 구성 소재들과 유사한 열팽창계수와 물리, 화학적인 안정성이 요구된다. 현재 연결재 제조기술은 plasma coating, sputtering, screen printing, 전사법등 다양한 연구가 진행되고 있다. 본 연구에서는 저렴한 비용으로 대량생산이 용이한 고상반응법을 적용하여 세라믹연결재를 제조하고, 그 특성을 연구하였다. 세라믹 연결재로서 선정한 합성조성은 $(La_{0.7}Ca_{0.3})(Cr_{0.9}Co_{0.1})O_3$로 SOFC 작동온도에서 높은 전기전도도를 나타낸다. LCCO 연결재를 1300, 1400 및 $1500^{\circ}C$에서 합성을 진행하였을 때 출발원료로 $CaCO_3$를 $CaF_2$로 대체하였을 때의 소결특성을 평가하였고, SEM과 XRD분석을 통하여 균질하고 결정성이 우수한 분말이 합성된 것을 확인하였고 DC impedance analyzer를 사용하여 전기전도도를 측정하였다. TMA를 사용하여 열팽창계수를 측정한 결과 YSZ(${\sim}10.8{\times}10^{-6}/^{\circ}C$)와 동일한 값을 나타내었다.

• Membrane Journal
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• v.28 no.2
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• pp.129-135
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• 2018

ZIFs (Zeolitic imdazolate frameworks) have attracted great attention as membrane materials in recent years due to their high chemical and thermal stability, high specific surface area and adjustable pore structure. In this study, ZIF-8 membranes were synthesized by in-situ growth method on two different support materials (${\alpha}$-alumina and YSZ) and their $H_2/CO_2$ gas permeation characteristics were investigated. In order to synthesize defect-free ZIF-8 layer, YSZ support required less synthesis time than ${\alpha}$-alumina support due to smaller pore size. After in-situ growth for 3 h, ZIF-8 membranes prepared on both YSZ and ${\alpha}$-alumina supports showed $H_2/CO_2$ selectivity of about 10.

• Journal of the Korean Institute of Gas
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• v.20 no.5
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• pp.96-103
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• 2016

Proper repair methods of damaged city gas pipeline is important factor to safely transmit gas and to reduce economical loss caused by failure of gas pipelines. Repair methods such as surfacing, type-A and type-B welding and composite sleeve method have been used to repair damaged city gas pipelines. In this paper, among repair methods, composite sleeve repair methods were conducted since they are rather simple processes and their repair quality is not sensitive to workers' ability compared with other repair methods. We discussed composite repair processes especially using carbon fiber prepregs and the experimental results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.141-146
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• 2016

Geotechnial engineering projects that requires excavation activity can cause massive ground deformation and this can damage adjacent structures. Depending on the engineering characteristics of ground material and the excavation depth, the ground movement is various. To overcome this issue, the ground deformation is monitored by multiple sensors. Typically, an inclinometer is installed behind the support wall. In this paper, we present an adaptive duty-cycling control mechanism using wireless sensors for monitoring ground deformation in excavations. The proposed mechanism dynamically adjusts the sleep time based on the urgency degree of sensed data from inclinometer. Through analytical evaluation of expected latency time, we confirm our adaptive duty-cycling mechanism has lower latency compared with periodic duty-cycling mechanism under variable conditions.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.26-35
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• 2009

This paper will propose the efficient method that should be designed to utilize the design pattern of GoF(Gang of Four) for implementation of LBS(Location Based Service) mobile system. The design method proposed by this paper can design and implement system interface using creational patterns, structural patterns and behavioral patterns of design pattern from the user and mobile system viewpoint. The design method using design pattern can show increasing reusability of module and software, abridging the development time, minimizing the maintenance and decreasing the efficiency of memory of system to software development. Therefore, we used a design pattern in order to change the middleware applying geographic information system from mobile environment. Finally, the mobile system applied to design pattern shall contribute to showing high stability and reliability, improving reusability and scalability of module and software and developing efficient LBS mobile system.

• Journal of the Korean Geosynthetics Society
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• v.5 no.3
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• pp.45-52
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• 2006

The collapsed cases are more and more increasing at the large scaled structures because of increasing of the risk due to natural disasters. The measuring instrument such as inclinometer, total station on reinforced-soil retaining wall has been used that displacement, settlement for stability assessment, maintenance and management of it. But because these has gotten many instability measuring factors for stability analysis of RRW, new system needs to complement disadvantage of existing system. In this study, we considered a application of Visual Monitoring System (VMS) to measure a displacement in face of wall through Lab. test about block assembly of segmental retaining wall during load test.

• Journal of the Korean Data and Information Science Society
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• v.20 no.6
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• pp.1061-1073
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• 2009

Stock price index option investing is a scientific investment method and various index and investment strategies have been developed. The purpose of this study is to apply the variety of option investment strategies that have been introduced in the market and validate them using past option trading data. Option data was based on an actual stock exchange market tick data ranging from September 2001 to January 2007. Visual Basic is used to propose an option back-testing model. Validation process was carried out by transferring the tick data into ten-minute intervals and empirically analyzed. Furthermore, most option-related strategies have been applied to the model, and the usefulness of each strategies can be easily evaluated. As option investment has high leverage followed by high risks and profit, the optimal option investment strategy should be used according to the market condition at the time to make stable profit with minimum risk.

• KSBB Journal
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• v.11 no.2
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• pp.165-172
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• 1996

To obtain a correctly folded human proinsulin, export of proinsulin using Staphylococcal protein A signal sequence-mediated secretion pathway has been attempted in E.coli. A secretion operon for proinsulin was constructed by consecutively connecting T7 promoter, SPA ribosome binding site, SPA signal sequence gene, and human proinsulin gene. Little immunoreactive proinsulin was detected in the periplasmic space and. culture medium, and not even in cytoplasmic space. The qualitative analysis of transcribed proinsulin mRNA and the in vitro transcription/translation experiment suggests that the negligible level of proinsulin export appears to be due to intracellular degradation of proinsulin, rather than due to the blockage during translocation. However, expression of proinsulin fusion protein such as MBP-proinsulin could dramatically increase export of proinsulin in E.coli.

• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.355-363
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• 2016

This study numerically investigates buckling behavior of press braked steel plates with a free edge that consists of the upper flange of U-shaped box girder. Since the press-braked plates include a rounded edge, the effective width to thickness ratio of the press-braked upper flange is obscure to determine the nominal compressive strength. This study performed 3D finite element analyses to evaluate an equivalent effective width of cold-formed plate with a free edge. Through the parametric numerical analyses, the elastic buckling stresses of the rounded corner plates were compared with those of general flat plates and then, the equivalent effective width has been estimated. A comparative study with Euler buckling formula speculated in the domestic design specifications has been conducted.