• 한국재료학회지
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• 제21권5호
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• pp.288-294
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• 2011

Simultaneous Ni and C codeposition by electrolysis was investigated with the aim of obtaining better corrosion resistivity and surface conductivity of a metallic bipolar plate for application in fuel cells and redox flow batteries. The carbon content in the Ni-C composite plate fell in a range of 9.2~26.2 at.% as the amount of carbon in the Ni Watt bath and the roughness of the composite were increased. The Ni-C composite with more than 21.6 at.% C content did not show uniformly dispersed carbon. It also displayed micro-sized defects such as cracks and crevices, which result in pitting or crevice corrosion. The corrosion resistance of the Ni-C composite in sulfuric acid is similar with that of pure Ni. Electrochemical test results such as passivation were not satisfactory; however, the Ni-C composite still displayed less than $10^{-4}$ $A/cm^2$ passivation current density. Passivation by an anodizing technique could yield better corrosion resistance in the Ni-C composite, approaching that of pure Ni plating. Surface resistivity of pure Ni after passivation was increased by about 8% compared to pure Ni. On the other hand, the surface resistivity of the Ni-C composite with 13 at.% C content was increased by only 1%. It can be confirmed that the metal plate electrodeposited Ni-C composite can be applied as a bipolar plate for fuel cells and redox flow batteries.

• 한국결정성장학회지
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• 제27권4호
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• pp.162-166
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• 2017

$Zn_{1-x}Ag_xSb$에서 Ag의 함량이 0~0.2인 열전화합물을 진공용해법으로 제조하여 결정상과 열전물성을 조사하였다. x = 0.05에서는 금속성 free Sb 상이 많이 생성되었고 이로 인해 전기전도도와 power factor가 크게 증가하였고 power factor는 제벡계수보다는 전기전도도에 의해 더 큰 영향을 받았다. x = 0.1 이상에서는 $Ag_3Sb$ 상이 현저하게 늘어났고 free Sb 피크는 약화되었다. 이에 따라 전기전도도와 power factor는 감소하기 시작하였고 이러한 경향은 더 많은 Ag가 첨가되면서 더욱 뚜렷하게 나타났다.

• 전자공학회논문지D
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• 제34D권12호
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• pp.89-100
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• 1997

This paper investigated a new type of low voltage threshold switch (LVTS). As distinguished from the many other types of electronic threshold switches, the LvTS is ; voltage controlled, occurs at low voltages ($V_{2}$ $O_{5}$lV devices. The average low threshold voltage < $V_{LVT}$>=218 mV (standard deviation =24mV~kT/q, where T=300K), and was independent of the device area (x100) and amorphous oxide occurred in an ~22.angs. thick interphase of the V/amorphous- $V_{2}$ $O_{5}$ contacts. At $V_{LVT}$ there was a transition from an initially low conductance (OFF) state into a succession of quantized states of higher conductance (ON). The OFF state was spatically homogeneous and dominated by tunneling into the interphase. The ON state conductances were consistent with the quantized conductances of ballistic transport through a one dimensional, quantum point contact. The temeprature dependence of $V_{LVT}$, and fit of the material parameters (dielectric function, barrier energy, conductivity) to the data, showed that transport in the OFF and ON states occurred in an interphase with the characteristics of, respectively, semiconducting and metallic V $O_{2}$. The experimental results suggest that the LVTS is likely to be observed in interphases produced by a critical event associated with an inelastic transfer of energy.rgy.y.rgy.

• 설비공학논문집
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• 제25권11호
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• pp.595-599
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• 2013

The pipes used in buildings are generally categorized into metallic or plastic materials. Metal pipes, such as copper and stainless steel pipes, are mainly used for water and hot water supply, and for the heating system. However, plastic pipes made of polyethylene and cross-linked polyethylene are used for floor heating, water drainage, and air vent systems. Usually, plastic pipes have thermal demerits, such as high linear expansion coefficients and bending phenomenon by hot water, although the pipes have several merits of light weight, low price, low thermal conductivity, and the comparatively high workability of metal pipes. Therefore, if those kind of demerits are overcome, plastic pipes can be easily accepted for hot water systems. This research is aimed to evaluate the applicability for vertical heating pipes of a plastic pipe system consisting of electric fusion fitting of a conductive carbon compound and propylene random glass fiber pipe, through measurement of the expansion rate and leakage in summer and winter seasons, in the apartment construction field.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.366.2-366.2
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• 2014

Impedance spectroscopy allows for simultaneous characterization of interface-controlled materials and/or devices in terms of electrical and dielectric aspects. Recently, there have tremendous interests in 2-dimensional electron gas layers (2DEGs) involving $LaAlO_3$ and $SrTiO_3$ whose features incorporates extremely high mobility and carrier concentrations along with metallic responses unlike the constituents, $LaAlO_3$ and $SrTiO_3$. Impedance spectroscopy offers the following unique features, such as simultaneous determination of conductivity and dielectric constants, identification of electrical origins among bulk-, grain boundary-, and electrode-based responses. Impedance spectroscopy was applied to the 2DEG $LaAlO_3/SrTiO_3$ system, in order to extract the electrical and dielectric information operating in the 2DEG system. The unique responses of the 2DEG system are investigated in terms of temperature and device structures. The underlying mechanism of the 2DEG system is proposed with the aim to optimizing the high-mobility 2DEG responses and to expedite the associated devices towards the high-density integrated chips.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.394.2-394.2
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• 2014

We fabricated highly transparent and flexible Ti doped In2O3 (TIO)/Ag nanowire(NW)/TIO (TAT) multilayer electrodes by linear facing target sputtering (LFTS) and brush-painting for used as flexible for anode organic solar cells(FOSCs). The characteristics of TAT transparent anode as a function of number of brush-painting cycles was also investigated. At optimized conditions we achieved highly flexible TAT multilayer electrodes with a low sheet resistance of $9.01{\Omega}/square$ and a high diffusive transmittance more than 80% in visible region as well as superior mechanical stability. The effective embedment of the Ag NW network between top and bottom TIO films led to a metallic conductivity, high transparency. Based on FE-SEM HRTEM, and XRD analysis, we can find that the Ag NW network was effectively embedded between top and bottom TIO layers due to good flexibility of Ag NW, the TAT multilayer showed superior flexibility than single TIO layer. Successful operation of FOSCs with high power conversion efficiency of 3.01% indicates that TAT hybrid electrode is a promising alternative to conventional ITO electrode for high performance FOSCs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.255-255
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• 2011

Zinc oxide based thin films have been extensively studied in recent several years because they have very interesting properties and zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technologies don't completely satisfy the industrial requirements. In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photoelectron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Increasing of the oxygen content in the gas mixture during deposition allow to obtain high-resistive protective and insulation coatings with high adhesion to the metallic surface.

• 폴리머
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• 제33권3호
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• pp.203-206
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• 2009

화학적 산화중합에 의한 Polyaniline Emeraldine salt(PANI-salt)는 도펀트로 존재하는 HCl과 같은 양성 자산으로 인한 금속성 사출금형 부식이 발생한다. 본 연구에서는 비극성 유기용매인 톨루엔, 포펀트와 계면활성제 역할을 하는 dodecylbenzenesulfonic acid(DBSA)를 사용하여 유화 중합법으로 PANI-salt를 합성한 후, 공용매 toluene에서 PANI-salt와 high impact polystyrene(HIPS)를 다양한 비율로 solution-cast 혼합하여 PANI-HIPS 블렌드를 얻었다. PT-IR과 UV-Vis.로 PANI-salt 구조를 확인하였고, PANI-HIPS 블렌드의 모폴로지, 열적 및 전기적 특성을 확인하였다. PANI(50 mL)와 HIPS(1 g)을 혼합하여 사출온도 $103^{\circ}C$, 사출압력 120 psi 하에서 사출한 PANI-HIPS 사출품에서 가장 높은 전기전도도($6.02{\times}10^{-5}\;S/cm$)가 나타났다.

• 전기화학회지
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• 제18권3호
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• pp.130-135
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• 2015

흑연 분말을 프탈로시아닌 또는 구리 프탈로시아닌과 함께 비활성 분위기에서 각각 열처리하여 표면처리를 진행하였고, 이의 속도특성과 저온 작동특성을 조사하였다. 표면처리 후 흑연 분말의 표면에 비정질 탄소와 구리의 코팅 층이 균일하게 형성되었다. 표면처리를 통하여 흑연 전극의 속도특성이 개선되는 것을 확인하였는데, 특히 구리 프탈로시아닌으로 처리한 경우 속도특성의 향상이 두드러졌다. 흑연 전극의 저항을 교류 임피던스와 펄스 저항측정법을 활용하여 조사하였는데, 구리 프탈로시아닌으로 처리된 흑연 전극의 경우가 저항이 가장 작았다. 프탈로시아닌으로 부터 유도된 비정질 탄소 층이 리튬이온의 확산을 용이하게 하고, 구리 프탈로시아닌으로부터 유도된 금속상태의 구리는 전자 전도도를 증가시키기 때문에 저항을 감소시키는 것으로 판단된다.

• 한국자기학회지
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• 제14권6호
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• pp.213-218
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• 2004

MBE장비를 이용하여 Mn과 Be nux의 변화를 주면서 Be-codoped GaMnAs를 성장시켰다. Mn flux의 범위는 고용체 특성의 GaMnAs에서, 과도한 nux에 의해 이차상이 형성된 상태까지 변화를 주면서 성장시켰다. Be병행 도핑 효과 연구를 위해 두 가지의 Be flux에서 박막을 성장하여 박막의 특성 변화를 관찰하였다. 과도한 Be도핑을 통해 금속성의 전도를 가지는 상태와, 상대적으로 적은 양의 도핑을 통해 캐리어의 수는 증가하였으나 반도체 전도를 보이는 상태이다. 적은 양의 Be이 병행 도핑된 GaMnAs의 경우, 상온에서 강자성 특성을 보였으나, 이차상 형성에 의한 전기 비저항의 증가와 작은 자기저항에 의해 자기 수송특성을 관찰하지 못했다. 그러나 많은 Be도핑에 의해 금속 거동을 보이는 경우에는 많은 수의 캐리어와 전기 전도토의 증가로 인해 자기 수송 특성을 관찰할 수 있었다. Be병행 도핑은 GaAs 기지 내에 효과적으로 캐리어를 공급하고, 이차상 MnAs 뿐만 아니라 MnGa의 형성을 촉진하는 것으로 생각된다.