• Journal of the Korean GEO-environmental Society
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• v.11 no.2
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• pp.23-32
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• 2010

Demand on pile foundation is rapidly increasing, as an investment for the social overhead capital getting enlarged in Korea. Steel piles are in general use in construction due to their workability and superior durability. But the recent global rise in steel price led the engineers to seeking for an economical alternative that still has equivalent characteristics as compared with the steel pile. In this regard a composite pile, in which steel suitable to resist the tensile stress are used in the upper part of the pile, while less expensive PHC pile is adopted in the lower part of the pile where axial stress should prevail, was studied and both pile loading test and load transfer test were performed for the piles which have been constructed for the foundation of a bridge in Korea. These test results and some theories already issued were compared, and it was shown that p-y nonlinear analysis gave rise to similar results.

• Composites Research
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• v.24 no.1
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• pp.31-36
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• 2011

Adhesive shear strengths of the established adhesives and the alternative adhesives were evaluated and their chemical structures were analyzed in order to investigate the possibility of replacing the established adhesives with the alternative adhesives applicable to the seeker for the guided missiles. Two types of the adhesives such as the structural adhesives and the sealant adhesives were considered. Those adhesives were exposed to the combined environmental factors consisting of temperature, moisture and ultraviolet over 1000 hours. Adhesive shear test was conducted to evaluate adhesive shear strengths and ATR FT-IR was utilized to investigate chemical structures. According to the results, the adhesive shear strengths of the alternative adhesives revealed higher than those of the established adhesives. Also the alternative adhesives were more stable to the combined environmental condition than the established adhesives. Therefore, it is found that the established adhesives were able to be replaced by the alternative adhesives.

• Composites Research
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• v.20 no.4
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• pp.1-8
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• 2007

In this study, carbon fiber reinforced polymeric (CFRP) composites with different resin composition were manufactured and resin formulation in composite materials were presented through tensile tests for cryogenic use. Thermo-mechanical cyclic loading (up to 6 cycles) was applied to CFRP unidirectional laminate specimens from room temperature to $-150^{\circ}C$. Tensile tests were then performed at $-150^{\circ}C$ using an environmental test chamber. In addition, matrix-dominant properties such as the transverse and in-plane shear characteristics of each composite model were measured at $-150^{\circ}C$ to examine the effects of resin formulation on their interfacial properties. The tensile tests showed that the composite models with large amounts of bisphenol-A epoxy and CTBN modified rubber in their resin composition had good mechanical performance at cryogenic temperature (CT).

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.141-142
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• 2008

국내 배전선로에서는 1999년부터 폴리머피뢰기를 설치하여 운영하고 있으나, 이들의 열화특성에 관한 데이터와 적합한 평가방법이 부족하여 장기적인 운영계획 수립이 어려운 상태이다. 이에 따라 본 논문에서는 폴리머피뢰기의 현장 열화인자를 인가할 수 있는 복합가속열화 시험장치를 제작하고 국내 환경조건을 모의할 수 있는 시험주기를 개발하여 폴리머피뢰기 완제품에 대한 장기신뢰성 평가법을 제안하였다. 그리고 가속열화시험 및 현장설치에 의한 전기적, 화학적 특성변화를 분석하여 폴리머피뢰기의 열화정도를 평가함으로써 본 연구에서 제안한 평가기법의 실효성을 검증하고 국산 폴리머피뢰기의 유지보수에 필요한 특성 데이터를 제시하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.567-568
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• 2021

In this paper, we design, fabricate, and test the performance of a cabin filter with LED modules of composite wavelengths containing UV-A and UV-C. Germs and air farms of the manufactured cabin filter confirmed sterilization capability in the sterilization test, and special chambers were manufactured to verify organic material decomposition capability in the organic compound decomposition test. Using colkates as photocatalytic was proved to be superior to using metal mash. The sterilization and air purification capabilities of the cabin filter produced throughout this study were verified through a similar environmental test.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.3
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• pp.31-36
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• 2012

In this study, the complex vibration reliability of Sn-3.5Ag and Sn-0.7Cu having a high melting temperature was investigated. For manufacturing of BGA test samples, Sn-3.5Ag and Sn-0.7Cu balls were joined on BGA chips finished by ENIG and the chips were mounted on PCB finished OSP by using reflow process. For measuring of resistance change during complex vibration test, daisy chain was formed in the test board. From the results of resistance change and shear strength change, the reliability of two solder balls was compared and evaluated. During complex vibration for 120 hours, Sn-0.7Cu solder was more stable than Sn-3.5Ag solder in complex vibration test.

• Journal of Adhesion and Interface
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• v.6 no.2
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• pp.13-20
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• 2005

Interfacial shear strength (IFSS) of environmentally friendly natural fiber reinforced polymer composites plays a very important role in controlling the overall mechanical performance. The IFSS of various Ramie and Kenaf fibers/epoxy composites was evaluated using the combination of micromechanical test and nondestructive acoustic emission (AE) to find out optimal conditions for desirable final performance. Dynamic contact angle was measured for Ramie and Kenaf fibers and correlated the wettability properties with interfacial adhesion. Mechanical properties of Ramie and Kenaf fibers were investigated using single-fiber tensile test and analyzed statistically by both uni-and bimodal Weibull distributions. An influence of clamping effect on a real elongation for both Ramie and Kenaf fibers were evaluated as well. Two different microfailure modes, axial debonding and fibril fracture coming from fiber bundles and single fiber composites (SFC) were observed under tension and compression.

• Journal of the Korean GEO-environmental Society
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• v.12 no.8
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• pp.59-67
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• 2011

The interaction of the ground deformation and composite piles, which is made of fiber glass, was analyzed for the effective pile application under vertical loads. This study was performed to conduct experimentation test and propose the material characteristics of the new type concrete injection circular FRP pile for the improvement of the defect of CFFT-Concrete composition piles and FRP-Concrete composition piles(FRP reinforced column direction). Additionally, in order to analyze the behaviour characteristics of composite pile and steel pile the numerical analyses were carried out.

• Journal of KSNVE
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• v.8 no.1
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• pp.13-20
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• 1998

도시생활에서 가장 짜증스러운 것은 자동차 소음이다. 경제발전과 더불어 인구의 도시 집중과 급격한 차량증가는 교통량이 많은 간선도로변을 중심으로 도로교통 소음문제가 야기되고 있으며, 우리나라도 지난 '97. 7월 자동차 1000만대 보유국이 되었다. 도로교통 소음은 자동차에서 발생하는 소음과 차량의 통행량, 차량의 주행속도및 도로주변 조건등 각종 요인이 복합 된 것으로 저속운행이 일반적인 도시에서는 자동차에서 발생하는 소음 중 엔진에서 나는 소음이 대개 60% 이상을 점하게 된다. 이러한 문제점 등을 감안하고 쾌적한 생활 환경 조성을 위하여 환경부에서는 제작차 소음 허용기준을 정하여 제작차가 시판되기전 단계에서 제작차 소음 허용기준에 적합하게 제작되는지 여부를 관리하기 위하여 인증제도를 시행 중에 있으며, 인증 시험에 통과된 차량에 대해서만 제작 시판할 수 있도록 법제화하여 운영하고 있다. 인증에 필요한 시험은 자동차의 가속주행소음, 배기소음 및 경적소음 시험으로써 본 장에서는 제작차 인증시험과 평가방법 등을 소개하고, 아울러 도로교통 소음 진동에 대하여서도 기술하고자 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.432-437
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• 2002

현재 비파괴 상태진단기술의 세계적인 연구동향은 비접촉식 시험기술, 실시간 광역기술, 고온 환경 하에서의 시험기술, 온라인 감시기술, 고감도, 고분해능, 소형화 및 무선통신기술 등을 개발하는 방향으로 연구가 활발히 진행되고 있다. 특히 고온 환경 하에서의 시험기술의 경우 철강공장 등에서 그 수요가 급증하고 있는데 반하여 국내의 경우 개발기술이 거의 전무하며 외국에서 전량 수입에 의존하고 있는 실정이다. 최근 여러 가지 다양한 복합재료와 공업용 재료들이 개발됨에 따라 이들 재료의 제작 공정이 복잡해질 뿐만 아니라 고온 및 고압의 공정조건이 요구되는 경우가 많다. 따라서 고온환경 하에서 재료의 특성을 비파괴적으로 검사할 수 있는 초음파 탐촉자가 요구된다고 하겠다. (중략)