• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.475-484
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• 2012

The purpose of this study is to help to prevent daily noises by measuring the noise absorption coefficient of the non-woven fabrics and wallpapers which are commonly used in lining and noise absorption coefficient of lining curtain. Seven types of fiber materials for the interior decoration, one non-woven fabric for the wallpaper linings, and two types of textiles for curtain linings are used as the experimental materials in this study. The noise absorption coefficient of the noise absorbents were measured by using impedance tube. And the thermal transmittance were measured by using thermal transmittance tester. The results of this study are as follows; Observing the noise absorption efficiency of each experimental materials, the combination of fiber materials and linings, the noise absorption efficiency of cotton, polyester and silk were similar and for the experimental materials of flax, rayon, acrylic and nylon were resulted the similar noise absorption efficiency. The result of combination of fiber material and black fabric was highest among the combined linings. For the combination of fiber material and non-woven fabric, double layers of non-woven fabric resulted slightly higher noise absorption coefficient result than single layer of non-woven fabric. The thermal transmittance and the sound absorbents of experimental materials were affected by the thickness, density and layer of air of the experimental materials.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.133-136
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• 2007

Perovskite-structured samarium strontium cobaltite (SSC), which is mixed ionic electronic conductor (MIEC), is considered as a promising cathode material for intermediate temperature-operating solid oxide fuel cell (SOFC) due to its high electrocatalytic property. Cathode material containing cobalt (Co) is unstable at high temperature and has a relatively high thermal expansion property. In this paper, Sm-Sr-(Co,Fe,Ni)-O system with perovskite and spinel structures was investigated in terms of electrochemical property and thermal expansion property, respectively. Area specific resistance (ASR) was measured by ac impedance spectroscopy to investigate the electrochemical property of cathode, and thermal expansion coefficient (TEC) was measured by using dilatometer. Micro structure of cathode was observed by scanning electron microscopy. Perovskite-structured $Sm_{0.5}Sr_{0.5}CoO_{3-\delta}$ showed the ASR of $0.87{\Omega}/cm^{2}$, and $Sm_{0.5}Sr_{0.5}NiO_{3-\delta}$, which actually has a spinel structure, showed the lowest TEC value of $13.3{\times}10^{-6}/K$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.132-137
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• 2002

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. The life of transformer is significantly dependent on the thermal behavior in windings. To analyse winding temperature rise, many transformer designer have calculated temperature distribution and hot spot point by finite element method(FEM). Recently, numerical analyses of transformer are studied for optimum design, that is electric field analysis, magnetic field, potential vibration, thermal distribution and thermal stress. In this paper, the temperature distribution of 50 kVA pole mold transformer for power distribution are investigated by FEM program and the temperature rise test of designed mold transformer carried out and test result is analyzed compare to simulation data. In this result, the designed mold transformer is satisfied to limit value of temperature and the other property is good such as voltage ratio, winding resistance, no-load loss, load loss, impedance voltage and percent regulation.

• Journal of the Korean institute of surface engineering
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• v.52 no.3
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• pp.123-129
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• 2019

With recent demand for the renewable energy resources, we conducted a research on the energy conversion and storage device of supercapacitor. The hybrid graphene-zinc oxide(GZO) electrodes for the supercapacitors (SCs) were fabricated and investigated. To increase the electrical conductivity of the GZO electrode, the rapid thermal annealing(RTA) in $Ar/H_2$(10%) atmosphere was applied and the effect was examined by comparing it with RTA at Ar atmosphere. In Raman spectroscopy, the electrodes annealed at 400? in $Ar/H_2$ atmosphere showed a lower ratio of D/G peak than that of annealed at Ar atmosphere, and had a larger specific capacitance(Sc) in the cyclic voltammetry(CV), and a lower the equivalent series resistance(ESR) in the electrochemical impedance spectroscopy(EIS). The reason seems to come from the better mixing of the graphene and zinc oxide by the RTA in $Ar/H_2$(10%).

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.67-72
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• 2008

We have studied the effect of heat treatment of multi-walled carbon nanotubes (MWNTs) as a counter electrode on the electro-chemical properties of dye-snsitized solar cells. MWNTs on the p-type Si substrate were synthesized by thermal chemical vapor deposition (CVD) using Fe catalysts. We prepared the two types of MWNTs samples with the different diameters. The rapid thermal annealing (RTA) treatment for the MWNTs was carried out at the growth temperature ($900^{\circ}C$) for 1 minute with $N_2$ gas atmosphere. The structural, electrical and electrochemical properties of MWNTs were investigated by field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, 2-point probe station and electrochemical impedance spectroscopy (EIS). The I(D)/I(G) ratio of heat-treated MWNTs in Raman spectra was considerably decreased. It was also found that the heat-treated MWNTs showed better redox reaction of iodide at the interface between MWNTs surface and electrolyte than that of as-grown MWNTs. The redox resistance value of heat-treated electrodes was measured to be much lower than that of as-grown electrode at the interface. As a result, the counter electrode using the heat-treated MWNTs showed better electrochemical properties.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.4
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• pp.300-308
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• 2010

This paper describes the development of a low-power electrocardiogram (ECG) touch sensor intended for the use with two dry metal electrodes. An equivalent ECG extraction circuit model encountered in a ground-free two-electrode configuration is investigated for an optimal sensor read-out circuit design criteria. From the equivalent circuit model, (1) maximum sensor resolution is derived based on the electrode's background thermal noise, which originates from high electrode-skin contact impedance, together with the input referred noise of instrumentation amplifier (IA), (2) 60 Hz electrostatic coupling from mains and motion artifact are also considered to determine minimum requirement of common mode rejection ratio (CMRR) and input impedance of IA. A dedicated ECG read-out front end incorporating chopping scheme is introduced to provide an input referred circuit noise of 1.3 ${\mu}V_{rms}$ over 0.5 Hz ~ 200 Hz, CMRR of IA > 100 dB, sensor resolution of 7 bits, and dissipating only 36 ${\mu}W$. Together with 8 bits synchronous successive approximation register (SAR) ADC, the sensor IC chip is implemented in 0.18 ${\mu}m$ CMOS technology and integrated on a 5 cm $\times$ 8 cm PCB with two copper patterned electrodes. With the help of proposed touch sensor, ECG signal containing QRS complex and P, T waves are successfully extracted by simply touching the electrodes with two thumbs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.261-264
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• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PAN/PVDF electrolytes as a function of a mixed ratio. PAN/PVDF based polymer electrolyte films were prepared by thermal gellification method of preweighed PAN/PVDF, plasticizer and Li salt. By adding PVDF and as a function of plasticizer mixed ratio to PAN-LiClO4 electrolyte, its conductivity was higher than that of PAN-$LiClO4_4$ electrolyte. The conductivity of PAN/PVDF electrolytes was $10^{-3}S/cm$. $10PAN10PVDFLiClO_4PC_5EC_5$ electrolyte shows the better conductivity of the others. Steady state current method and ac impedance used for the determination of transference numbers in PAN/PVDF electrolyte film. The transference number of $10PAN10PVDFLiClO_4PC_5EC_5$ electrolyte is 0.45.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.51-56
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• 2004

Conductive polymer blends and composites are widely used for different safety application such as electrostatic charge dissipation(ESD), electromagnetic interference(EMI) shielding, electrostatic prevention and safety chemical sensor. In order to prepare a impedance-type humidity sensor that is durable at high humidities and high temperature, electically conductive polymer blends based on diallyldimethylammonium chloride(DADMAC) and epoxy were prepared in this study. The polymer blends type conductive ionomer exhibits reaction each other DADMAC and epoxy in FT-IR and DSC analysis. The blends material was traced by new peak at 1600cm-1 and appeard improvement of thermal resistance by melting point shift. Alumina substrate was deposited a pair of gold electrodes by screen printing. The blend material were spin-coated with a thin film type on the surface of alumina substrate. The polymer bleld type sensor exhibits a linear impedance increasing better than DADMAC coated humidity sensor. Also it shows good sensitivity, low hysteresis and durability against high humidity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.306-311
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• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity impedance spectroscopy and electrochemical properties of PDF/PAN electrolytes as a function of a mixed ratio were reported for PVDF/PAN based polymer electrolyte films which were prepared by thermal gellification method of preweighed PVDF/PAN plasticizer and Li salt. The conductivity of PVDF/PAN electrolytes was 10$\^$-3/S/cm. 20PVDF5PEN LiCiO$\_$4//PC$\_$10//EC$\_$10/ electrolyte has the better conductivity compared to others. 20PVDF5PANLICIO$\_$4//PC$\_$10//EC$\_$10/ electroylte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and ac impedance were used for the determination of transference numbers in PVDF/PAN electrolyte film. The transference number of 20PVDF5PANLiCO$\^$4//PC$\_$10//EC$\_$10/ electrolyte is 0.48.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.2
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• pp.141-148
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• 2006

This study was carried out to analyze the microstructure characteristics of electrolyte membrane through XRD, SEM and AC impedance measurement for using in high temperature steam electrolysis(HTE). It was investigated that thermal stability and electric characteristics by sintering condition using dry and wet process, and confirmed growth of particle and density change by sintering temperature. The sintering temperature and behavior had an effect on the relative density of the ceramic and the average grain size. The more amount of dispersant in organic compound increase, the more the density increased. But the binder was shown opposite phenomenon. It was analyzed that electrolyte resistance and electrical characteristics using AC impedance. The electrical properties of YSZ grain boundary changed with the sintering temperature.