• 한국전기전자재료학회논문지
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• 제24권9호
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• pp.744-749
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• 2011

Recently, annual usage of energy is dramatically increasing because industrialization is going faster and more electricity is needed due to various electronic devices. This study focused on the performance characteristics of solar cell using the impedance technique. The experiment measured an impedance according to frequency's from 2 mHz until 1 MHz. It could know that the impedance was decreased according to the frequency increases in solar cell. The imaginary part was changed from capacitance component to inductance component.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.510-511
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• 2008

Fuel cell is a modular, high efficient and environmentally energy conversion device, it has become a promising option to replace the conventional fossil fuel based electric power plants. The high temperature fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. And, The research and development for the solid oxide fuel cell have been promoted rapidly and extensively in recent years, because of their high efficiency and future potential. Therefore this paper describes the manufacturing method and characteristics of anode electrode for solid oxide fuel cell, by the way, Ni-YSZ materials are used as anode of high temperature widely. So in this experiments, we investigated the optimum content of Ni, by the impedance characteristics, overvoltage. As a result, the performance of Ni-YSZ anode(40vol%) was better excellent than the others.

• 조명전기설비학회논문지
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• 제18권6호
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• pp.230-237
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• 2004

본 논문에서는 인버터에서 발생하는 맥동전류가 양자 교환막형 연료전지에 미치는 영향을 임피던스 모델을 통하여 분석한다. 제안된 방법은 주파수 응답 분석법을 이용하여 연료전지 스택의 등가 임피던스를 유도하고, 유도된 모델을 이용하여 맥동전류의 영향을 분석한다. 모델을 통해 계산된 결과는 상용 연료전지 스택을 사용한 실험을 통하여 증명된다. 실험결과는 인버터에 의해 발생한 맥동전류로 인해 최대 10(%)까지 연료전지 스택의 출력이 감소할 수 있음을 보인다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권1호
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• pp.1-10
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• 2005

This paper presents the development of a microsystem for whole blood purification and electrophysiological analysis of the purified cells. Magnetophoresis using continuous diamagnetic capture (DMC) was utilized for whole cell purification and electrical impedance spectroscopy (EIS) was utilized for electrophysiological analysis of the purified cells. The system was developed on silicon and plastic substrates utilizing conventional microfabrication technologies and plastic microfabrication technologies. Using the magnetophoretic microseparator, white blood cells were purified from a sample of whole blood. The experimental results of the DMC microseparator show that 89.7% of the red blood cells (RBCs) and 72.7% of the white blood cells (WBCs) could be continuously separated out from a whole blood using an external magnetic flux of 0.2 T. EIS was used as a downstream whole cell analysis tool to study the electrophysiological characteristics of purified cells. In this work, primary cultured bovine chromaffin cells and human red blood cells were characterized using EIS. Further analysis capabilities of the EIS were demonstrated by successfully obtaining unique impedance signatures for chromaffin cells based on the whole cell ion channel activity.

• 전기학회논문지
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• 제59권1호
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• pp.102-107
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• 2010

Dye-sensitized solar cell (DSC) has been expected to be an alternative to the conventional silicon solar cell due to simple manufacturing process and low fabrication casts. In order to improve productivity of DSC, we attempted to optimize the required time of the adsorption process. According to the change in the adsorption time from 1 to 24h, We analyzed the output characteristics and the change of internal impedance. As a result, The outputs of DSC were continuously increased until 12h of the adsorption time and remained the same after that. Also, We reconfirmed this result that 12h was optimum adsorption by the analysis of the electrochemical impedance spectroscope because the internal impedance was similar to the output.

• 센서학회지
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• 제14권1호
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• pp.33-41
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• 2005

For more convenient electrode-electrolyte interface impedance analysis in biosensor, a stand-alone impedance measurement system is required. In our study, we developed a PC-based portable system to analyze impedance of the electrochemical cell using microprocessor. The devised system consists of signal generator, programmable amplifiers, A/D converter, low pass filter, potentiostat, I/V converter, microprocessor, and PC interface. As a microprocessor, PIC16F877 which has the processing speed of 5 MIPS was used. For data acquisition, the sampling rate at 40 k samples/sec, resolution of 12 bit is used. RS-232 with 115.2 kbps speed is used for the PC communication. The square wave was used as stimuli signal for impedance analysis and voltage-controlled current measurement method of three-electrode-method were adopted. Acquired voltage and current data are calculated to multifrequency impedance signal after Fourier transform. To evaluate the implemented system, we set up the dummy cell as equivalent circuit of which was composed of resistor, parallel circuit of capacitor and resistor connected in parallel and measured the impedance of the dummy cell; the result showed that there exist accuracy within 5 % errors and reproduction within 1 % errors compared to output of Hioki LCR tester and HP impedance analyzer as a standard product. These results imply that it is possible to analyze electrode-electrolyte interface impedance quantitatively in biosensor and to implement the more portable high speed impedance analysis system compared to existing systems.

• 센서학회지
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• 제26권1호
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• pp.15-23
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• 2017

In this study, bioelectrical impedance analysis, which has been used to assess an alteration in intracellular fluid (ICF) of the body, was applied to detect intravenous infiltration. The experimental results are described as follows. Firstly, when infiltration occurred, the resistance gradually decreased with time and frequency i.e., the resistance decreased with increasing time, proportional to the amount of infiltrated intravenous (IV) solution. At each frequency, the resistance gradually decreased with time, indicating the IV solution (also blood) accumulated in the extracellular fluid (ECF) (including interstitial fluid). Secondly, the resistance ratio started to increase at infiltration, showing the highest value after 1.4 min of infiltration, and gradually decreased thereafter. Thirdly, the impedance ($Z_C$) of cell membrane decreased significantly (especially at 50 kHz) during infiltration and gradually decreased thereafter. Fourthly, Cole-Cole plot indicated that the positions of (R, $X_C$) shifted toward left owing to infiltration, reflecting the IV solution accumulated in the ECF. The resistance ($R_0$) at zero frequency decreased continuously over time, indicating that it is a vital impedance parameter capable of detecting early infiltration during IV infusion. Finally, the mechanism of the current flowing through the ECF, cell membrane, and ICF in the subcutaneous tissues was analyzed as a function of time before and after infiltration, using an equivalent circuit model of the human cell. In conclusion, it was confirmed that the infiltration could be detected early using these impedance parameters during the infusion of IV solution.

• 한국세라믹학회지
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• 제45권12호
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• pp.788-795
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• 2008

An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.918-923
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• 2007

Fuel cell is a modular, high efficient and environmentally energy conversion device, it has become a promising option to replace the conventional fossil fuel based electric power plants. The high temperature fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. Corrosions in molten electrolytes and the electric conductivity across the oxide scale have crucial characteristics. When molten salts are involved, high temperature corrosions become severe. In this sense, corrosions of alloys with molten carbonates have the most severe material problems. Systematic investigation on corrosion behavior of Fe/21Cr/Ti or Al alloy has been done in (62+38)mol% (Li+K)$CO_3$ melt at $650^{\circ}C$ using the electrochemical impedance spectroscopy method. It was found that the corrosion current of these Fe-based alloys decreased with increasing Al or Ti. And Al addition improved the corrosion resistance of this type of specimen and more improvement of corrosion resistance was observed at the specimen added with Al.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2222-2227
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• 2007

Newly structured metal-supported solid oxide fuel cell was fabricated and characterized by impedance analysis and galvanodynamic experiment. Using a cermet adhesive, thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support of which flow channel was fabricated. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_3$ perovskite oxide was used as cathode material. Single cell performance was increased and saturated at operating time to 300hours at 800$^{\circ}C$ because of cathode sintering effect. The sintering effect was reinvestigated by half cell test and exchange current density was measured as 0.005A/$cm^2$. Maximum power density of the cell was 0.09W/$cm^2$ at 800$^{\circ}C$. Numerical analysis was carried out to classify main factors influencing the single cell performances. Compared to experimental IV curve, simulated curve based on experimental parameters such as exchange current density was in good agreement.