• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.707-712
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• 1991

N'-phenyl-N-(2-chloroethyl)-N-aminourea has been prepared from N'-phenyl-N-(2-chloroethyl)-N-nitrosourea by means of the electrochemical reduction with the mercury pool electrolytic cell. In order to find out the optimum condition of the reaction, the voltammetric behaviors for N'-aryl-N-(2-chloroethyl)-N-nitrosourea derivatives have been investigated by the cyclic voltammetry and polarography. The peak potentials was shifted to the negative direction as the pH value of the solution decrease. The substituent effects of phenyl ring on the peak potential were not observed in this case. (5:3) EtOH/4 N-HCl mixed solution was employed for the electrolysis. The applied potential was -0.7 V vs. Ag/AgCl/4 N-HCl electrode. The number of electrons participated to the reduction process was 4, respectively. The product was identified by FT-IR, NMR, mass and/or elemental analysis data.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.196-197
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• 2015

ZnSe의 전기화학적 거동은 각각 다른 pH를 갖는 전해질에서의 linear sweep voltammogram 분석에 의해 체계적으로 고찰되었다. 제어된 조성을 갖는 칼코지나이드 ZnSe 박막이 complexing agent의 역할을 하는 citrate를 포함한 알카리 용액에서 전해 증착되었다. 다른 pH의 전해질에서 증착된 ZnSe 박막의 형상을 분석하고, 추가적으로 다른 pH의 전해질 및 어닐링 온도 변화에 따른 ZnSe 박막의 XRD분석이 이루어졌다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.133-133
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• 2008

본 연구에서는 임상적으로 사용후 임플란트시스템의 안정성을 조사하기 위하여 인위적으로 풀림 조임을 1회와 20회로 반복한 후 0.9% NaCl에서 부식을 시키고 파괴한 후 임플란트시스템의 안정성에 대하여 조사하였다.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.669-679
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• 2022

Lithium-ion battery has been used for lots of electronic devices. With the popularization of batteries, researchers have focused on batteries' electrochemical performances by environmental conditions, such as temperature, vibration, shock and charging state. Meanwhile, due to very serious global warming, car companies have started using lithium-ion batteries even in cars, replacing internal combustion engines. However, batteries have been developed based on non-moving systems which is totally different from vehicles. In the line of the differences, researchers have tried to reveal relationship between variables from dynamic systems and batteries. In this review, we discuss the comprehensive effect of vibration and shock on batteries. We firstly summarize vibration profiles and effect of normal vibration on batteries. We also sum up effect of shock and penetration on batteries and introduce how ultrasound influences on batteries. Lastly, outlook for the battery design as well as dynamic design of EVs are discussed.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.592-597
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• 2014

The graphite/$SiO_2$ composites as anode materials for lithium-ion batteries were prepared by sol-gel method to improve the graphite's electrochemical characteristics. The prepared graphite/$SiO_2$ composites were analysed by XRD, FE-SEM and EDX. The graphite surface modified by silicon dioxide showed several advantages to stabilize SEI layer. The electrochemical characteristics were investigated for lithium ion battery using graphite/$SiO_2$ as the working electrode and Li metal as the counter electrode. Electrochemical behaviors using organic electrolytes ($LiPF_6$, EC/DMC) were characterized by charge/discharge, cycle, cyclic voltammetry and impedance tests. The lithium ion battery using graphite/$SiO_2$ electrodes had better capacity than that of using graphite electrodes and was able to deliver a discharge capacity with 475 mAh/g at a rate of 0.1 C. Also, the capacity retention ratio of the modified graphite reaches 99% at a rate of 0.8 C.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.145-146
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• 2016

In this study, Corrosion behavior in mortar was observed by the passage of time by using EIS method. As a result of EIS experiment, equivalent circuit and changes of Impedance parameter could be observed. In addition, it was confirmed that impedance of rebar in mortar and corrosion rate according to the amount of NaCl were different.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.155-155
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• 2016

DLC (Diamond like Carbon)는 Diamond와 유사한 물리화학적 특성을 보유한 막으로 고경도 및 우수한 내마모성, 화학적 안정성의 특성을 가지고 있다. DLC는 크게 카본의 막 형성 공정에서 카본 소스에 따라 수소가 포함된 DLC와 무수소 DLC 로 구분된다. Tetrahedral amorphous carbon (ta-C) 박막은 DLC 박막 중에서 가장 다이아몬드와 유사한 특성을 가지는 박막으로, a:C-H에 비해 고온안정성, 높은 경도 (30~80 GPa) 및 내마모 특성이 우수하여, 현재 다양한 응용분야에 적용되고 있으며, 최근에는 고내구성을 보유하면서 전기적 특성을 가지는 기능성 DLC막의 요구가 증대하고 있다. 본 연구에서는 무수소 DLC 형성을 위해 자장필터가 장착된 Filtered Vacuum Arc Source (FVAS)를 자체적으로 개발하여 연구를 수행하였다. FVAS 장비는 카본 이온 발생부와 Plasma Duct 부위, 전자석부위 구성되어 있으며, 본 연구에서는 Plasma Duct 부위의 Bias 제어를 통한 음극에서 기판으로 이동하는 카본이온의 에너지 및 flux 변화를 통해 ta-C 막의 전기적, 기계적 물성 연구를 진행하였다. Plasma Duct Bias 변화는 각 0 ~ 20 V 조건으로 진행하였으며, 물성 평가는 경도 (Hardness), 마찰계수, 전기적 특성에 대한 분석을 진행하였다. 박막의 증착 거동에서는 Plasma Duct bias 변화에 따라 10 V에서 가장 높은 증착 거동을 가지다 감소하는 경향을 확인 하였으며, 박막의 물성 특성 평가 시에도 이와 유사하게 특성의 차이를 관찰하였다. 이는 음극부위에서 형성된 카본이온이 기판에 도달 시에 Plasma Duct Bias 변화에 따라 이온의 Flux 및 에너지 변화로 인한 박막의 밀도 및 ta-C 막의 물성 변화로 예상되며, 이를 분석하기 위해 라만 분석법을 통해 증명하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.217-228
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• 2009

In case of application of electrophoresis method for leakage restoration of waste impoundment, main points of consideration were to evaluate the mobility of clay particles by electrophoretic force and capacity of leakage repair in leachate electrolyte system contained with various chemical species. However, the flocculation phenomena of clay particles induced by electrochemical interaction between various chemical species and clay particles would cause the big problems in electrophoresis method. Therefore, a series of laboratory tests such as one-dimensional electrophoresis and gravitational experiments were carried out in order to identify the specific chemical species affected flocculation of clay particles and the range of chemical concentration in leachate. In addition, the characteristics of clay particle behavior with chemical species and concentration range in leachate were analized using the concept of the settling velocity, zeta potential, and electrophoretic velocity.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.246-251
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• 2003

전기분해법을 이용하여 수용액 중의 질산성 질소의 환원거동에 대한 연구를 통하여 수용액중의 질산 함량을 제어하는 연구를 수행하였다. 촉매전극을 채택한 복극전해조에서 30분의 조업에 질산 100ppm 이하의 저농도 용액은 70%, 300ppm 이상의 고농도의 경우는 90%까지 질소를 용이하게 제거할 수 있었다. 초기 질소농도가 증가하면서 한계전류밀도도 크게 증가하였으며, pH가 감소할수록 환원전류가 증가하였다. 그리고 수용액의 pH는 질소 환원반응기구에 큰 영향을 주는 것으로 판명되었으며, 산성에서는 질소형태로 중성 혹은 염기성에서는 암모니아 형태로 환원되는 것으로 추정된다.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.65-75
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• 2017

C-S-H phase is the most abundant reaction product, occupying about 50~60% of cement paste volume. The phase is also responsible for most of engineering properties of cement paste. This is not because it is intrinsically strong or stable, but because it forms a continuous layer that binds together the original cement particles into a cohesive whole. The binding ability of C-S-H phase arises from its nanometer-level structure. In terms of chloride penetration in concrete, C-S-H phase is known to adsorb chloride ions, however, its mechanism is very complicated and still not clear. The purpose of this study is to examine the interaction between chloride ions and C-S-H phase with various Ca/Si ratios and identify the adsorption mechanism. C-S-H phase can absorb chloride ions with 3 steps. In the C-S-H phase with low Ca/Si ratios, momentary physical adsorption could not be expected. Physical adsorption is strongly dependent on electro-kinetic interaction between surface area of C-S-H phase and chloride ions. For C-S-H phase with high Ca/Si ratio, electrical kinetic interaction was strongly activated and the amount of surface complexation increased. However, chemical adsorption could not be activated for C-S-H phase with high Ca/Si ratio. The reason can be explained in such a speculation that chloride ions cannot be penetrated and adsorbed chemically. Thus, the maximum chloride adsorption capacity was obtained from the C-S-H phase with a 1.50 Ca/Si ratio.