• 한국응용과학기술학회지
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• 제17권2호
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• pp.113-119
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• 2000

Alkylation of phenol with tert-butanol in the liquid phase on mordenite was studied. The influence of many reaction parameters such as calcination temperature, reaction temperature, t-butanol/phenol molar ratio on catalytic properties was discussed. The main products were 2,4-di-t-butylphenol, o-t-butylphenol, p-t-butylphenol, the last of these was wanted product. In order to enhance the selectivity of p-t-butylphenol, optimum conditions were recommended at $500^{\circ}C$ calcination temperature, $140^{\circ}C$ reaction temperature, 1.0 molar ratio of reactants over mordenite. P-t-butylphenol was formed with 90% isomer selectivity at optimum conditions after 4hr reaction. On the basis of the behavior obtained in the cases mentioned, optimum conditions and catalytic properties for t-butylation of phenol were provided.

• 수산해양교육연구
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• 제19권3호
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• pp.323-328
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• 2007

This paper was studied on the effect of the specific resistance of water on corrosion characteristics of STS 304 for gas boiler. The electrochemical polarization test of STS 304 for gas boiler was carried out. And the polarization resistance, uniform corrosion, corrosion behavior by impressed potential and corrosion sensitivity of STS 304 with specific resistance were considered. The main results are as following: 1) With being low the specific resistance of water, the polarization resistance and corrosion potential of STS 304 decreases, while corrosion current density increases. 2) Under constant impressed potential, the corrosion sensitivity of STS 304 is large with being low the specific resistance due to synergy effect of Cl ion.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.181-181
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• 2006

We developed a novel method to fabricate a nerve guide conduit (NGC) with the porosity of submicron pore sizes (to prevent fibrous tissue infiltration) and hydrophilicity (for effective oxygen and nutrient permeation) using poly(lactic-co-glycolic acid) (PLGA) and Pluronic F127 by a modified immersion precipitation method designed by our laboratory. It was recognized that the hydrophilized PLGA/F127 (3 wt%) tube can be a good candidate as a NGC from the analyses of its morphology, mechanical strength, hydrophilicity, model nutrient permeability and in vivo nerve regeneration behavior using a rat model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2528-2530
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• 2004

Neural network minimization problems are often conditioned and in this contribution way to handle this will be discussed. It is shown that a better conditioned minimization problem can be obtained if the problem is separated with respect to the linear parameters. This will increase the convergence speed of the minimization. One of the most powerful uses of neural networks is in function approximation(curve fitting)[1]. A main characteristic of this solution is that function (f) to be approximated is given not explicitly but implicitly through a set of input-output pairs, named as training set, that can be easily obtained from calibration data of the measurement system. In this context, the usage of Neural Network(NN) techniques for modeling the systems behavior can provide lower interpolation errors when compared with classical methods like polynomial interpolation. This paper solve of single-variable minimization using neural network.

• Journal of the Korean Wood Science and Technology
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• 제29권3호
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• pp.21-26
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• 2001

Acquisition of precise information on drying characteristics of wood is indispensable for the improvement of drying schedules and wood quality. Recognition of the exact moisture content at which drying defects such as checks occur during drying with given drying conditions may be essential to reduce drying losses. In this study an image-processing system was combined with a laboratory-scale wood dry kiln for experiments and the surface of tree disk of black locust (Robinia pseudoacacia L.) was monitored to investigate the behavior of check formation over all the drying process. This system showed good potential for improving drying schedules and wood product quality.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.225-231
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• 2005

This study aims to suggest an evaluation methodology of green-tourism potential for village level with amenity resources in rural areas. The amenity resources system was classified into three sub-classes(social, industrial, and natural/cultural/historical resources) and a relationship diagram between three classes and tourists' behavior was also defined. The methodology considers human resources in the village including the three sub-class amenity resources. The table and diagram were applied to make renewal plan for rural villages of the study area, Nami-myun, Keumsan-gun, Chungnam province, so that the development scheme for the villages was suggested reasonably by the new findings of this study.

• 전력전자학회논문지
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• 제25권3호
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• pp.219-226
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• 2020

Given the change in the energy market, large energy storage systems (ESS) is rapidly entering the market. In this rapid spread, fire accidents are becoming an issue. This study attempts to approach the fire from the system point of view to analyze the problems caused by bonding from different perspectives. Moreover, to conduct this study, the fabrication of real objects is dangerous, which needs to be verified through simulation. In this study, we approach the cause of fire that occurs in large-capacity ESS from the system perspective. We focus on determining the effects of cell balancing performed on the BMS after charging. Thus, we analyze the cell balancing behavior and the linkage risks to the various stacks. The study also explores why no fire occurs during 70% operation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.177-178
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• 2015

This paper presents a neutral point deviation compensating control algorithm applied to a 3-level NPC converter. The neutral point deviation is analyzed with a focus on the current flowing out of or into the neutral point of the dc link. Based on the zero sequence components of the reference voltages, this paper analyzes the neutral point deviation and balancing control for 3-level NPC converter. An analytical method is proposed to calculate the injected zero sequence voltage for NP balancing based on average neutral current. This paper also proposes a control scheme compensating for the neutral point deviation under generalized unbalanced grid operating conditions. The positive and negative sequence components of the pole voltages and ac input currents are employed to accurately explain the behavior of 3-level NPC converter. Simulation and experimental results for a test set up of 30kW are shown to verify the validity of the proposed algorithm.

• 한국자기학회지
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• 제5권5호
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• pp.631-635
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• 1995

Longitudinal magnetic recording process of thin film media was simulated by the 2-D finite element method (FEM). To describe precisely the hysteresis behavior of thin film media, scalar Preisach model was used. In this paper, we discussed the formation of bit patterns and importance of modeling of minor loops in high density recording. The effects of the media coercivity and film thickness on the remanent magnetization and transition shape were investigated.

• 대한기계학회논문집A
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• 제37권5호
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• pp.641-648
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• 2013

보 구조물들은 보다 우수한 성능을 위하여 다양한 형태의 보강재 또는 단면 형상을 가지게 된다. 강성재단을 설계에 적용하기 위해서는 강성재단에 의해서 발생하는 연계 거동을 정확하게 예측하는 것이 필요하다. 본 연구에서는 문헌에서 보고된 복합재료 보의 특이한 연계거동(면외 굽힘-전단 연계)을 실험적으로 확인하기 위하여, 등가의 동적 연계거동을 나타내는 강성재단 된 등방성 박스보를 제작하였다. 제작된 시편의 주파수 및 모드 형상 등의 동적 특성을 3 차원 유한요소해석과 비교 검토하여, 문헌에 보고된 특이한 전단 연계 거동이 발생함을 확인하였다. 이러한 거동은 보강재의 적절한 배치를 통해 원하는 방향으로 강성재단 될 수 있고, 얻어진 연계 거동은 다양한 분야에 응용될 수 있다.