• 대한교통학회지
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• 제29권4호
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• pp.7-15
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• 2011

도심 교통체증 감소와 물류의 신속한 이동을 위해 1990년대 초반 등장한 퀵서비스산업은 이륜자동차의 증가를 가속화 했으며, 경제발전에 따라 250CC 이상 대배기량의 이륜자동차들도 레저용으로 급증하고 있는 추세를 보이고 있다. 사고발생추세에서 전체교통사고대비 2005년 5.7%, 2008년 8.3%로 점차 증가추세를 보이며 사망률 또한 증가하고 있다. 본 연구에서는 이륜자동차의 자동차전용도로 통행에 대한 위험도를 알아보고자 서울시 연속류 도로를 대상으로 이륜자동차의 법규위반율과 차로변경 행태, 주행속도 행태를 분석하였으며 사고시의 차량충격량을 PCCRASH 시뮬레이션으로 산출하였다. 분석 결과, 차로변경시간과 평균통행속도가 일반차량과 상이하며 도로정체가 발생할 경우 부적절한 주행행태를 보이는 것으로 나타났다. 정부의 이륜자동차 자동차전용도로 허용 검토에 있어 본 연구는 허용여부를 판단하는데 도움이 되며 이륜자동차의 주행 행태를 연구하는데 기초자료로 활용할 수 있다.

• Nuclear Engineering and Technology
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• 제24권2호
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• pp.154-162
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• 1992

원전 증기발생기 2차측 화학세정시 두가지 주요 목표는 슬러지 제거를 효과적으로 하는 것과 모재금속의 부식을 최소화하는데 있다. 본 연구에서는 전기화학 실험과 슬러지 용해 실험을 통하여 제동공정 중에 어떤 인자들이 중요한 역할을 하는지 확인하고 외국에서 개발된 두가지 제동공정에 대하여 안전성 측면과 슬러지 제거 효과를 비교. 평가하고자 하였다. 38$^{\circ}C$에서 EDTA, NH$_4$OH. EDA를 사용하는 제동공정에 있어서 $H_2O$$_2$는 구리슬러지 제거에 적합한 전위구역으로 구리의 전위를 높여주는데 매우 효과적이었다. 이런 전위구역에서 SA 285 Grade C와 Alloy 600 재료의 부식속도는 매우 작았다. 그러나 전위가 -450 mV 이하로 유지될 때 SA 285 Grade C 재료의 부식속도 증가가 예상된다. 6$0^{\circ}C$에서 EDA, (NH$_4$)$_2$CO$_3$를 사용하는 공정은 구리의 부식전위가 -200 mV이상으로 유지될 때 효과적인 제동이 가능하였으나 전위를 공기주입과 용액교반으로 이 구역으로 올리기는 매우 어려웠다.

• 한국산학기술학회논문지
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• 제15권10호
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• pp.6114-6125
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• 2014

본 연구에서는 시설감귤농가와 시설포도 농가들을 대상으로 농업 에너지 절감시설과 신재생에너지원의 이용행태를 조사 분석하였다. 농가들의 에너지 이용행태를 조사한 결과, 농업 에너지 절감 시설과 신재생에너지의 이용 및 운영 관리 시스템은 여전히 미흡한 수준으로 나타났다. 시설감귤 농가와 시설포도 농가를 대상으로 실시한 IPA분석 결과에 따르면, 에너지 절감시설과 관련된 항목들에 대하여 전반적으로 중요도는 높았으나 수행도(만족도)는 크게 낮은 것으로 나타났다. 유류비 부담 등으로 인해 재배면적이 감소추세에 있는 시설감귤 농가의 경우 '관련 보조시설 확충 지원'이나 '기술개발', '저비용 대체에너지 보급문제'에 대해서는 중요하다고 판단되지만 실제 수행도는 매우 낮게 나타났다. 반면 재배면적이 증가하고 있는 시설포도농가의 경우 '에너지 절감시설에 대한 AS 용이성', '지역별 여건을 고려한 지원정책', '절감시설에 대한 기술개발'에 대해서 모두 우위를 나타냈다. 영농 광열비의 증가는 결국 농가경영에 부담을 증가시키고 대외 경쟁력을 떨어뜨리는 위험성을 갖고 있다. 현재 농가들이 사용하고 있는 등유는 열효율적인 면에서 손실이 많기 때문에 경유, 증유 등을 지속적으로 사용 할 수 있도록 기존 노후화 시설에 대한 개보수 지원과 함께 대체에너지의 보급 확대를 위한 방안이 마련되어야 한다.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.451-458
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• 2017

An Electric Vehicle (EV) is operated with the electric energy of a battery in place of conventional fossil fuels. Thus, a suitable charging infrastructure must be provided to expand the use of electric vehicles. Because the battery of an EV must be charged to operate the EV, expanding the number of EVs will have a significant influence on the power supply and demand. Therefore, to maintain the balance of power supply and demand, it is important to be able to predict the numbers of charging EVs and monitor the events that occur in the distribution system. In this paper, we predict the hourly charging rate of electric vehicles using transformation matrix, which can describe all behaviors such as resting, charging, and driving of the EVs. Simulation with transformation matrix in a specific region provides statistical results using the Monte-Carlo Method.

• Structural Engineering and Mechanics
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• 제57권6호
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• pp.1051-1064
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• 2016

Link-to-column connections in Eccentrically Braced Frames (EBFs) have critical role in their safety and seismic performance. Accordingly, in this study, contribution of supplemental stiffeners on hysteretic behavior of the link-to-column connection is investigated. Considered stiffeners are placed on both sides and parallel to the link web between the column face and the first stiffener of the link. Hysteretic behaviors of the link beams with supplemental stiffeners are numerically investigated using a pre-validated numerical model in ANSYS. It turned out that supplemental stiffeners can change energy dissipation mechanism of intermediate links from shear-flexure to shear. Both rectangular and trapezoidal supplemental stiffeners are studied. Moreover, optimal placement of the supplemental stiffeners is also investigated. Obtained results indicate a discrepancy of less than 9% in maximum link shear of the numerical and experimental specimens. This indicates that the numerical results are in good agreement with those obtained from the test. Trapezoidal supplemental stiffeners improve rotational capacity of the link. Moreover, use of two supplemental stiffeners at both ends of the link can more effectively improve hysteretic behavior of intermediate links. Supplemental stiffeners would also alleviate the imposed demands on the connections. This latter feature is more pronounced in the case of two supplemental stiffeners at both ends of the link.

• 한국막학회:학술대회논문집
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• 한국막학회 1998년도 춘계 총회 및 학술발표회
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• pp.97-98
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• 1998

1. Introduction : Polypropylene(PP) membrane is widely used in the field of microfiltration and ultrafiltration. However, the hydrophobicity of PP causes the adsorption of hydrophobic and amphoteric solutes in the feed. Surface modification techniques of membrane through the treatment of hydrophilizing agents, coating of hydrophilic compounds, UV, plasma and high energy irradiation, etc. can have a great effect on propensities to prevent the protein from staining membranes. Among them, the modification to hydophilize membrane surface using UV is very simple and effective. Recently many studies for more effective surface modification have been conducted. Iwata et al. prepared membranes by grafting polyethylene glycol diacrylate macromer(PEGDA) onto polysulfone with plasma using a glow discharge reactor which prevent the oil from staining the membrane. The primary mechanism contributing to the membranes is preventing the oil from directly contacting the surface of the membrane as the PEGDA chains dissolved into emulsion. To evaluate their feasibility for use as a anti-fouling separation membrane, we prepared hydrophilic membranes by UV irradiation method and investigated their characteristics.

• Advances in aircraft and spacecraft science
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• 제2권3호
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• pp.275-302
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• 2015

Theoretical and numerical assessments of approximate evaluations and simplified analyses of piezoelectric structures transverse shear modal effective electromechanical coupling coefficient (EMCC) are presented. Therefore, the latter is first introduced theoretically and its approximate evaluations are reviewed; then, three-dimensional (3D) and simplified two-dimensional (2D) plane-strain (PStrain) and plane-stress (PStress) piezoelectric constitutive behaviors of electroded shear piezoceramic patches are derived and corresponding expected short-circuit (SC) and open-circuit (OC) frequencies and resulting EMCC are discussed; next, using a piezoceramic shear sandwich beam cantilever typical benchmark, a 3D finite element (FE) assessment of different evaluation techniques of the shear modal effective EMCC is conducted, including the equipotential (EP) constraints effect; finally, 2D PStrain and PStress FE modal analyses under SC and OC electric conditions, are conducted and corresponding results (SC/OC frequencies and resulting effective EMCC) are compared to 3D ones. It is found that: (i) physical EP constraints reduce drastically the shear modal effective EMCC; (ii) PStress and PStrain results depend strongly on the filling foam stiffness, rendering inadequate the use of popular equivalent single layer models for the transverse shear-mode sandwich configuration; (iii) in contrary to results of piezoelectric shunted damping and energy harvesting popular single-degree-of-freedom-based models, transverse shear modal effective EMCC values are very small in particular for the first mode which is the common target of these applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.55-55
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• 2010

We use ab initio density functional theory to determine the effect of bundling on the equilibrium structure, electronic and magnetic properties of $Mo_6S_{9-x}I_x$nanowires with x = 0, 3, 4.5, 6. Each unit cell of these systems contains two $Mo_6S_{6-x}I_x$ clusters connected by S3 linkages to form an ordered linear array. Due to the bi-stability of the sulfur linkages, the total energy of the nanowires exhibits typically many minima as a function of the wire length. We find that nanowires can switch over from metallic to semiconducting by applying axial stress. Structural order is expected in bundles with x=0 and x=6, since there is no disorder in the decoration of the Mo clusters. In bundles with other stoichiometries, we expect structural disorder to occur. We find the optimum inter-wire distance to depend sensitively on the orientation of the wires, but only weakly on x. It is also found that the electronic properties of nanowires are affected strongly due to bundling of nanowires exhibiting very unusual Fermi surfaces. Furthermore, ferromagnetic behaviors are observed in selected stable and many more unstable atomic arrangements in nanowire bundles.

• Applied Microscopy
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• 제50권
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• pp.17.1-17.9
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• 2020

Recent advances in fabrication have enabled radial-junction architectures for cost-effective and high-performance optoelectronic devices. Unlike a planar PN junction, a radial-junction geometry maximizes the optical interaction in the three-dimensional (3D) structures, while effectively extracting the generated carriers via the conformal PN junction. In this paper, we report characterizations of radial PN junctions that consist of p-type Si micropillars created by deep reactive-ion etching (DRIE) and an n-type layer formed by phosphorus gas diffusion. We use electron-beam induced current (EBIC) microscopy to access the 3D junction profile from the sidewall of the pillars. Our EBIC images reveal uniform PN junctions conformally constructed on the 3D pillar array. Based on Monte-Carlo simulations and EBIC modeling, we estimate local carrier separation/collection efficiency that reflects the quality of the PN junction. We find the EBIC efficiency of the pillar array increases with the incident electron beam energy, consistent with the EBIC behaviors observed in a high-quality planar PN junction. The magnitude of the EBIC efficiency of our pillar array is about 70% at 10 kV, slightly lower than that of the planar device (≈ 81%). We suggest that this reduction could be attributed to the unpassivated pillar surface and the unintended recombination centers in the pillar cores introduced during the DRIE processes. Our results support that the depth-dependent EBIC approach is ideally suitable for evaluating PN junctions formed on micro/nanostructured semiconductors with various geometry.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1892-1900
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• 2023

A protective oxide layer forms on the material surfaces of a Nuclear Power Plant during operation due to high temperature. These oxides can host radionuclides, the activated corrosion products of fission products, resulting in decommissioning workers' exposure. These deposited oxides are iron oxides such as Fe₃O₄, Fe₂O₃ and mixed ferrites such as nickel ferrites, chromium ferrites, and cobalt ferrites. Developing a new chemical decontamination technology for domestic CANDU-type reactors is challenging due to variations in oxide compositions from different structural materials in a Pressurized Water Reactor (PWR) system. The Korea Atomic Energy Research Institute (KAERI) has already developed a chemical decontamination process for PWRs called 'HyBRID' (Hydrazine-Based Reductive metal Ion Decontamination) that does not use organic acids or organic chelating agents at all. As the first step to developing a new chemical decontamination technology for the Pressurized Heavy Water Reactor (PHWR) system, we investigated magnetite dissolution behaviors in various HyBRID inorganic acidic solutions to assess their applicability to the PHWR reactor system, which forms a thicker oxide film.