• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1600-1602
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• 1997

We have studied microstructure of carbn fiber and graphite using scanning electron microscope, x-ray diffractommetry and x-ray photoelectron spectroscopy. According to the results, intercalation of lithium ion affected formation of film on carbon surface and changed structural parameter. Also, we found that film on carbon surface included lithium ion. And, the results of XPS indicated that surface of lithiated carbon materials existed P and F consisting electrolyte. Thus, We expected electrolyte cointercalated with lithium.

• Carbon letters
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• v.15 no.1
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• pp.71-76
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• 2014

Activated carbon nanofibers (ACNF) were prepared from polyacrylonitrile (PAN)-based nanofibers using $CO_2$ activation methods with varying activation process times. The surface and structural characteristics of the ACNF were observed by scanning electron microscopy and X-ray diffraction, respectively. $N_2$ adsorption isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. As experimental results, many holes or cavernous structures were found on the fiber surfaces after the $CO_2$ activation as confirmed by scanning electron microscopy analysis. Specific surface areas and pore volumes of the prepared ACNFs were enhanced within a range of 10 to 30 min of activation times. Performance of the porous PAN-based nanofibers as an electrode for electrical double layer capacitors was evaluated in terms of the activation conditions.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.129-136
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• 2007

자연광의 이용은 큰 어려움 없이 지속 가능한 에너지 기술을 구현할 수 있는 방안으로 고려되고 있다. 여러 개의 작은 반사경을 적용한 태양 추적식 자연채광 시스템은 비교적 단순한 메카니즘을 적용하여 그 성능과 효용성의 극대화를 꾀할 수 있으며, 또한 그 제작, 설치 작동 그리고 활용성에서 상당한 이점이 있다. 본 연구에서는 작은 mini-dish형 반사경(직경<30cm 이하)을 이용한 화이버 광학 집광기의 설계, 제작 및 작동 특성에 대하여 소개하고, 아울러 광추적 프로그램인 Photopia를 이용하여 그 성능에 대한 시뮬레이션을 수행하였다. 주요 구성 요소에서의 광추적에 의한 시뮬레이션 결과치는 실제 시스템의 설계 및 성능 예측에 중요한 기술적 데이터를 제공하며, 특히 실측이 곤란한 측정 면에서의 빛의 경로 해석에 유용하게 적용될 수 있다.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.777-781
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• 2008

In this work, silver nanoparticles-containing polyacrylonitrile (PAN) solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of nanofibers. The inputted voltage and PAN content in the solution were fixed at 15 kV and 10 wt.% in DMF with 10 cm of tip-to-collector distance (TCD). The PAN/Ag nanofiber webs were stabilized by oxidation at 250 ${^{\circ}C}$ for 2 h in air and carbonized at 1000 ${^{\circ}C}$ for 2 h in $N_2$. The resultant diameter distribution and morphologies of the nanofibers were evaluated by scanning electron microscope analysis. The electrochemical behaviors of the nanofiber webs were also observed by cyclic voltammetry tests. It was found that the presence of silver nanoparticles in carbon nanofiber webs led to the increase of specific capacitance and the decrease of fiber diameters.

• 연구논문집
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• s.30
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• pp.43-56
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• 2000

N-IR spectroscopy technology is very useful. And, the technology has wide application range. In the range, we know that single beam type silica analyzer has some handicap. So we were studied Splitted beam type silica analyzer. This dissertation have been discuss about system structure, system fundamentals and performance test. At the test, we were study in the spectral interference of NH3. We know that existing system had some problem. It is structural frailties of single beam type. Therefore we were study for Splitted beam type structure. And we obtain a good result. We have $\pm$5% accuracy and 0.5 ppb level measuring range. But, we have a question. It is ppt level measuring technology by the laser beam spectroscopy.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.533-538
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• 2007

Since glass-fiber reinforced composite decks have high-strength, light-weight and high durability, many researches on the composite decks for bridges are currently performed and many composite decks are developed. Some of the developed composite decks can be applied as rigmats for temporary roads such as oil developing temporary roads. In this paper, a composite deck for rigmat is developed and studied. Structural behavior of the developed composite deck for rigmat is verified by both analysis and experiment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.539-544
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• 2007

Glass fiber reinforced composite decks have high-strength, light-weight and high durability. The composite decks having vertical snap-fit connections are designed for pedestrian bridges and their structural behaviour are studied. The existing connection method of the composite decks in horizontal direction is replaced by the developed snap-fit connection method in vertical direction. The section shape of the composite decks having the vertical snap-fit connection is designed. The safety of the vertical snap-fit connection is verified by finite element analysis.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.59-64
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• 2017

The general manufacturing problem can be described as the achievement of a predefined product quality with given equipment, cost and time constraints. Unfortunately, for some quality characteristics of a product such as surface roughness it is hard to ensure that these requirements will be met. Stainless steels STS 304 is frequently used as shaft materials in small fiber reinforced polymer(FRP) fishing boats. In this work, the dry turning parameters of STS 304 are optimized by using Taguchi method. The experiments were conducted at three different cutting speeds with three different feed and three different depth of cut. The cutting parameters are optimized using signal to noise ratio and the analysis of variance. The effects of cutting speed and feed on surface roughness was analyzed. The results revealed that the spindle speed is the more significant parameter influencing the surface roughness.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.253-258
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• 2000

The purpose of this paper is to propose the deduction equation of shear strength of high strength reinforced concrete beams input steel fibrous. To propose the deduction equation of shear strength, we studied high reasonable verification by comparing proposal equation with other researches such as equation of ACI code 318-95 or equation of Zsutty. To propose the deduction equation of shear strength, regression analysis was done using MINITAP program. Finally, it has been tried to make an improvement of brittleness quality of high strength concrete which has been weak points and it is convinced the result by increase of deflection and strain about loads.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.23-26
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• 2010

In this study, it was performed damage assesment of small scale composite aircraft developing. This aircraft adopted the sandwich structure to skin of wing. This study aims to investigate the residual strength of sandwich composites with Nomex honeycomb core and carbon fiber face sheets after the open hole damage by the experimental investigation. The 4-point bending tests were used to find the bending strength, and the open hole was applied to introduce the simulated damage on the specimen. The bending strength test results after open hole was compared with the results of no damaged specimen test. The FEM analysis is assessed via an experimental 4-point bending test.