Insulating TaNx films were grown by plasma enhanced atomic layer deposition using butylimido tris dimethylamido tantalum and N2+H2 mixed gas as metalorganic source and reactance gas, respectively. Crossbar devices having a Pt/TaNx/Pt stack were fabricated and their electrical properties were examined. The crossbar devices exhibited temperature-dependent nonlinear I (current) - V (voltage) characteristics in the temperature range of 90-300 K. Various electrical conduction mechanisms were adopted to understand the governing electrical conduction mechanism in the device. Among them, the Poole- Frenkel emission model, which uses a bulk-limited conduction mechanism, may successfully fit with the I - V characteristics of the devices with 5- and 18-nm-thick TaNx films. Values of ~0.4 eV of trap energy and ~20 of dielectric constant were extracted from the fitting. These results can be well explained by the amorphous micro-structure and point defects, such as oxygen substitution (ON) and interstitial nitrogen (Ni) in the TaNx films, which were revealed by transmission electron microscopy and UV-Visible spectroscopy. The nonlinear conduction characteristics of TaNx film can make this film useful as a selector device for a crossbar array of a resistive switching random access memory or a synaptic device.

Recently, as demand for Electric Car has been increasing, it has been a main factor that maximizing performance and ensuring the stability of the Electric Car battery to increase the reliability of Electric Car. Above all the study on thermal control in a big influence on the performance and battery life is growing in parallel. This study has compared cooling effect of an Electric Car battery between battery with Heat Sink and without Heat Sink for optimum design of Electric Car battery. Battery is simply modeled into four cells, divided into two cases of battery with Heat Sink that attached on the cell's side and without Heat Sink. And this research was conducted on forced convection. The battery which is designed by this way was numerically analyzed by CFX 14.5. Numerical results, revealed that the battery with Heat Sink was superior in terms of cooling effect. According to the numerical analysis by battery cell's temperature variations, the battery with Heat Sink turned out to be superior in cooling effect to the battery without Heat Sink.

In this study, electric propulsion leisure boat with 9 meters length is designed and the performances are investigated by CFD analysis and model test. Maximum speed of the developed boat is 15knots(7.7 m/s) using 80Kw electric motor. Catamanan type hull form with slender body is adopted considering high Froude number and large deck area. Two kinds of hull forms are designed and the performances are compared in resistance point of view. Wave patterns are observed to make clear the relationship between resistance performance and wave characteristics. The results show that not only wave interaction due to shoulder waves but also stern waves have a strong influence on resistance performance and CFD analysis including free surface can give useful informations at initial ship design stage for high Froude number catamaran boat.

We performed this study to understand the effect of a single-crystalline anode on the mechanical properties of asdeposited films during electrochemical deposition. We used a (111) single- crystalline Cu plate as an anode, and Si substrates with Cr/Au conductive seed layers were prepared for the cathode. Electrodeposition was performed with a standard 3-electrode system in copper sulfate electrolyte. Interestingly, the grain boundaries of the as-deposited Cu thin films using single-crystalline Cu anode were not distinct; this is in contrast to the easily recognizable grain boundaries of the Cu thin films that were formed using a poly-crystalline Cu anode. Tensile testing was performed to obtain the mechanical properties of the Cu thin films. Ultimate tensile strength and elongation to failure of the Cu thin films fabricated using the (111) single-crystalline Cu anode were found to have increased by approximately 52 % and 37%, respectively, compared with those values of the Cu thin films fabricated using apoly-crystalline Cu anode. We applied ultrasonic irradiation during electrodeposition to disturb the uniform stream; we then observed no single-crystalline anode effect. Consequently, it is presumed that the single-crystalline Cu anode can induce a directional/uniform stream of ions in the electrolyte that can create films with smeared grain boundaries, which boundaries strongly affect the mechanical properties of the electrodeposited Cu films.

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinolformaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and N2 adsorptiondesorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

The Fe-Cr-Al alloy system shows an excellent heat resistance because of the formation of an Al2O3 film on the metal surface in an oxidizing atmosphere at high temperatures up to 1400oC. The Fecralloy needs an additive that can act as a binder because of its bad compactability. In this study, the green compacts of STS434L and Al powder added to Fecralloy are oxidized at 950oC for up to 210 h. Fecralloy and Al is mixed by two types of ball milling. One is vented to air and the other was performed in a sealed jar. In the case of Al addition, there are no significant changes in the electrical resistance. Before the oxidation test, Al oxides are present in the Fecralloy surface, as determined from the energy dispersive spectroscopy results. The addition of Al improves the compactability because of an increased density, and the addition of STS434L increases the electrical resistivity by forming a composite oxide.

당뇨병 환자들은 말초신경 손상의 합병증으로서 이상감각과 통증을 느낄 수 있는데 이는 날카로운 느낌, 차갑고 시린 느낌, 무딘 느낌, 살갗이 벗겨진 듯한 예민한 느낌, 화끈거리는 느낌, 따끔하고 가려운 느낌 등 다양하게 나타날 수 있다. 이를 진단하기 위해서 여러 선별검사와 전기생리학적 검사를 활용할 수 있다. 본 연구에서는 신경병통증척도와 미시간 신경병증 선별도구 및 신경전도검사를 통해 이상감감/통증을 호소하는 당뇨병 환자 11명과 호소하지 않는 당뇨병 환자 10명 간에 차이점 및 특징을 분석하였고, 세부 감각양상과 신경전도검사 지표간 상관성을 분석하였다. 그 결과 이상감각/통 증을 호소하는 환자군에서 신경병통증척도와 미시간 신경병증 선별검사의 점수가 통계적으로 유의하게 높았고 신경전도검 사에서는 주로 정중신경 운동신경과 비골신경이 의미 있는 기능 변화를 보였다. 세부 감각양상에 따른 신경전도검사 지표는 주로 정중신경 운동신경, 후경골신경, 장딴지신경에서 유의한 변화를 보였다. 이러한 결과들은 감각이상과 통증이 실제 말초신경 이상과 관련이 있음을 시사한다. 향후 많은 수의 대상자를 포함한 추가적인 연구가 필요하다.

연구에서는, 전기방사법을 이용하여 산화철-산화그래핀(Fe3O4/GO, metallic graphene oxide; MGO)이 도입된 PVdF/MGO 복합나노섬유(PMG)를 제조하였으며, 이를 활용하여 비소제거에 대한 특성 평가를 진행하였다. MGO의 경우 In-situ-wet chemical 방법으로 제조하였으며, FT-IR, XRD분석을 진행하여, 형태와 구조를 확인하였다. 나노섬유 분리막의 기 계적 강도 개선을 위하여 열처리과정을 진행하였으며, 제조된 분리막의 우수한 기계적 강도 개선 효과를 확인할 수 있었다. 그러나, PMG 막의 경우, 도입된 MGO의 함량이 증가할수록 기계적 강도가 감소되는 경향성을 보여주었으며, 기공크기 분석 결과로부터, 0.3~0.45 μm의 기공크기를 가진 다공성 분리막이 제조되었음을 확인할 수 있었다. 수처리용 분리막으로의 활용 가능성 조사를 위해, 수투과도 분석을 실시하였다. 특히, PMG2.0 샘플의 경우 0.3 bar 조건에서, PVdF 나노섬유막(91 kg/m2h)에 비해 약 70% 향상된 결과값(153 kg/m2h)을 나타내었다. 또한, 비소 흡착실험 결과로부터, PMG 막의 경우, 비소3 가와 5가에 최대 81%, 68%의 높은 제거율을 보여주었으며, 흡착등온선 분석으로부터, 제조된 PMG 막의 경우 비소3가, 5가 모두 Freundlich 흡착거동을 따른다는 것을 확인하였다. 위 모든 결과로부터, PVdF/MGO 복합 나노섬유 분리막은 비소제거 및 수처리용 분리막으로 충분히 활용할 수 있을 것으로 판단된다.

염수전기분해(saline water electrolysis) 또는 클로로-알칼리 막공정(chlor-alkali membrane process)은 양이온교환 막과 전극으로 구성되는 전해셀에 전기를 가하여, 고순도(> 99%)의 고부가가치 화합물(예 : 염소, 수소, 수산화나트륨)을 직 접 제조하는 화학공정이다. 염수전기분해의 경제성은 동일한 양의 화합물을 생산하기 위해 투여되는 에너지 소비량을 저감 시킴으로 달성될 수 있다. 이러한 이슈는 전해질이나 전극의 고유 저항을 줄이거나, 전해질과 전극 사이의 계면 저항을 감소 시킴으로 달성시킬 수 있다. 본 연구에서는 전자빔 동시조사법을 사용하여, 높은 화학적 안정성을 지닌 탄화수소계 술폰산 이 오노머 막의 표면에 높은 이온선택성을 갖는 고분자를 접목 시키는 시도가 이루어졌다. 이를 통해, 고분자 전해질 막의 이온 전도성을 보완함과 동시에, 전극과의 계면 저항을 감소시켜, 전기화학적 효율 향상이 이루어짐을 관찰하였다.

We report on the fabrication and characterization of a novel Cu2O/CuO heterojunction structure with CuO nanorods embedded in Cu2O thin film as an efficient photocathode for photoelectrochemical (PEC) solar water splitting. A CuO nanorod array was first prepared on an indium-tin-oxide-coated glass substrate via a seed-mediated hydrothermal synthesis method; then, a Cu2O thin film was electrodeposited onto the CuO nanorod array to form an oxide semiconductor heterostructure. The crystalline phases and morphologies of the heterojunction materials were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated Cu2O/CuO heterojunction photocathode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the Cu2O/CuO photocathode was found to exhibit negligible dark current and high photocurrent density, e.g. −1.05 mA/cm2 at −0.6 V vs. Hg/HgCl2 in 1 mM Na2SO4 electrolyte, revealing the effective operation of the oxide heterostructure. The photocurrent conversion efficiency of the Cu2O/CuO photocathode was estimated to be 1.27% at −0.6 V vs. Hg/HgCl2. Moreover, the PEC current density versus time (J-T) profile measured at −0.5 V vs. Hg/HgCl2 on the Cu2O/CuO photocathode indicated a 3-fold increase in the photocurrent density compared to that of a simple Cu2O thin film photocathode. The improved PEC performance was attributed to a certain synergistic effect of the bilayer heterostructure on the light absorption and electron-hole recombination processes.

Membrane based water and wastewater treatment becomes more and more popular; however, membrane fouling is still a critical obstacle for its extensive use. Most of the membranes being used are polymeric and have limitations in physical, chemical, and thermal stability, even though various novel materials were introduced. In this study, metal membranes were fabricated to solve those weak points of polymeric membranes. We evaluated the physical properties of a metal membrane, such as pore size distribution, surface morphology, and water flux, and finally used the membrane for electrochemical oxidation of municipal wastewater with simultaneous hydrogen fuel generation. The metal membrane removed 50-70% of the feed organic matter by electrochemical oxidation; 10-30 % removal by electrochemical oxidation plus 40% by membrane rejection.

Ionomers are polymeric materials containing fixed charged ions (e.g., – SO3 -) to transport their counter ions (e.g., H+, Li+, Na+ and so on) selectively and have been widely used as key components for membrane and unit cell formation targeted for renewable energy generation (e.g., polymer electrolyte membrane fuel cells(PEMFC), redox flow batteries, and reverse electrodialyses) and valued chemical production (e.g., water and brine electrolysis). There are advantages such as high processability, easy solvent evaporation, and chemical inertness, when the ionomers are in the dissolved or dispersed states in water-alcohol mixtures to be applied for these applications. Unfortunately, it is difficult to make homogeneous solution or dispersion using the ionomers with hydrophilic levels undissolved in water. In this study, water-alcohol nanodipsersion with perfluorinated or hydrocarbon sulfonic acid ionomers are fabricated and their feasibilities as PEMFC and electrolysis materials are evaluated.

역삼투막 기술은 이온을 효과적으로 제거할 수 있어 다양한 분야에 널리 활용되고 있으며, 가정용 정수기에도 사용되고 있다. 그러나 역삼투막 기술은 투과율과 회수율이 낮은 단점이 있다. 소형 가전제품에 적용하기 위해서는 이러한 단점들을 극복하는 것이 필요하다. 이를 극복할 수 있는 대체 기술의 하나로 전 기탈이온 방식을 들 수 있다. 전기탈이온 방식은 역삼투막과 중공사막의 장점을 결합한 것으로 이온교환 및 전극 소재에 전기를 걸어 높은 제거율과 풍부한 유량을 구현하는 기술이다. 또한, 전기적인 힘을 조절해 역삼투막급(순정수)와 미네랄을 함유한(청정수)를 생성할 수 있다. 본 발표에서는 전기탈이온 기술 개발 동향에 대해서 소개하고 소형 가전제품에 적용하기 위한 응용 연구사례를 소개하고자 한다.

The limitations and problems of the rechargeable battery and short mileage per one electric charging have not been overcome at the electric vehicles. To solve these problems, the hybrid vehicle has been developed by securing the performance of automotive with the conventional internal combustion engine and the environmental benefit. Meanwhile, the electric UTV (utility terrain vehicle) which has this environmental benefit has been widely used for factories, parks, leisure and agricultural areas. In this study, the electric UTV was fabricated and attached the auxiliary power drive systems including the photovoltaic power generation system into this electric vehicle in order to make up the hybrid (motor + photovoltaic) vehicle system. As the range of the hybrid UTV would be extended over 20% than that of the existing golf cart per one electric charging through this successful development, the dynamic stiffness was improved through light-weight body design.