• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.1
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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.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.192-198
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• 2021

The battery's State of Health (SOH) is a critical parameter in the process of battery use, as it represents the Remaining Useful Life (RUL) of the battery. Electrochemical Impedance Spectroscopy (EIS) is a widely used technique in observing the state of the battery. The measured impedance at certain frequencies can be used to evaluate the state of the battery, as it is intimately tied to the underlying chemical reactions. In this work, a low-cost portable EIS instrument is developed on the basis of the ARM Cortex-M4 Microcontroller Unit (MCU) for measuring the impedance spectrum of Li-ion battery packs. The MCU uses a built-in DAC module to generate the sinusoidal sweep perturbation signal. Moreover, it performs the dual-channel acquisition of voltage and current signals, calculates impedance using a Digital Lock-in Amplifier (DLA), and transmits the result to a PC. By using LabVIEW, an interface was developed with the real-time display of the EIS information. The developed instrument was suitable for measuring the impedance spectrum of the battery pack up to 1000 V. The measurement frequency range of the instrument was from 1 hz to 1 Khz. Then, to prove the performance of the developed system, the impedance of a Samsung SM3 battery pack and a Bexel pouch module were measured and compared with those obtained by the commercial instrument.

• Journal of Power Electronics
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• v.16 no.2
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• pp.695-703
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• 2016

A fuel cell power conditioning system for online diagnosis and load leveling under the condition of varying load is developed in this study. The proposed system comprises a unidirectional boost converter and a bidirectional buck-boost converter with a battery. The system operates in two different modes. In normal mode, the bidirectional converter is utilized for load leveling; in diagnostic mode, it is utilized to control load voltage while the boost converter generates perturbation current to implement the online diagnosis function through in-situ electrochemical impedance spectroscopy (EIS). The proposed method can perform EIS for a fuel cell under varying-load conditions with no influence on the load. The validity and feasibility of the proposed system are verified by experiments, and the design procedure of the proposed system is detailed.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.216-217
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• 2019

The battery powered electric vehicle (EV) is one of most promising technologies in 21^st century. Though the lithium batteries are playing an important role in the EVs, they are only applicable until their capacities reach 80%, the end of its useful first life. Yet, these batteries can live a second life such as Energy Storage Systems (ESS). In order to utilize the Residual Useful Life (RUL) of the batteries the State of Health (SOH) of them needs to be estimated by a nondestructive test such as Electrochemical Impedance Spectroscopy (EIS) technique. Though many kinds of different EIS instruments are commercially available, most of them can only test a battery module less than 10V and the price of the instrument is very high. In this paper a low-cost EIS instrument suitable for measuring the impedance spectrum of the high voltage battery module is proposed and its validity is verified through the experiments. In order to prove the accuracy of the developed EIS instrument its measured impedance spectrum is compared with the results obtained by a commercial instrument. The Chi Square value calculated between two impedance spectrum measured by both developed and commercial instruments are less than 2%, which prove the strong correlation between two results.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.100.1-100.1
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• 2011

Electrochemical impedance spectroscopy(EIS) are using widely as a useful technique mainly in the field of electrochemical for the analysis of electrode reactions or characteristics of the composites. The response analysis of the systems technique provides comprehensive informations about the characteristic and structure of complex and internal reaction. The EIS is the method to measure impedance of the measurement target classified by the frequency, it select the equivalent impedance model to give same response from the result and it calculate the parameter. Therefore, the chemical reaction inside the fuel cell is to modeling to electrical impedance. And as repeating the same experiment in each of the operating point, we can get each different parameter. As a result, we can establish the equivalent impedance model in each operating point. Therefore, if we use these models, we can evaluate the fuel cell without the internal design parameter of the fuel cell as required in existing modeling. The EIS is used typically technique for distinguish status of fuel cell called SOH(State Of Health). When the fuel cell is degradation, Efficiency and health of the fuel cell is reduced because internal impedance is increase. As usage of these principles, we can evaluate state of fuel cell through the impedance analysis of fuel cells. In this study, we are presents EIS distinction system and algorithm for residential fuel cell systems. At the time of the fuel cell installation in the fields, the EIS system and proposed algorithm will be able to apply as technique for efficiency and performance evaluation about fuel cell system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.107-108
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• 2022

In recent years, the construction industry has a tendency to increase of high-rise builidngs. High rise buildings can use limited space efficiently. But High rise buildings have problem that have extremely heavy weight. Various studies are being conducted to reduce the weight of buildings. Although lightweight aggregate is a meterial that can effectively reduce the weight of buildings, the strength of the aggregate itself is weak and the absorption rate is high, so the strength of the ITZ(Interfacial Transition Zone) area is weak. Therefore, it is essential to improve the interfacial area when using lightweight aggregates. In this study, an experiment was conducted to improve the adhesion between the aggregate and cement paste and to strengthen the interfacial area by coating the surface of the lighteight aggregate with Blast Furnace Slag. To confirm the improvement, compressive strength and EIS(Electrochemical Impedance Spectroscopy) measurements were perfromed. Using EIS, the change in electrical resistance of the cement hardened body was confirmed. As a result, it was confirmed that the lightweight aggregate coated on the surface showed highter compressive strength and electrical resistance than the non-coated lightweight aggregate, and that the coating material was filled in the interfacial area and inside the aggregate that helped to strengthen the compresssive strength and higher electrical resistance.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.659-662
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• 2005

Electrochemical impedance spectroscopy (EIS) has been extensively used to try to evaluate the corrosion state of the steel/concrete system. This technique is attractive because, in theory, used in a wide range of frequencies, it can give detailed information about the mechanisms and kinetics of the electrochemical reactions. Impedance measurements were performed using potential control and measuring the corresponding current response. One-year-old southern exposure test. specimens were used in the current study. The effectiveness of corrosion inhibiting additives was evaluated. The corrosion current densities estimated by impedance measurements were confirmed by those determined using linear polarization techniques. The purpose of this study was to evaluate the long-term-performance potential of the corrosion inhibitors in chloride contaminated reinforce concrete.

• Journal of Power Electronics
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• v.12 no.1
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• pp.223-231
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• 2012

In this paper, criteria for better selection of a supercapacitor through EIS (Electrochemical Impedance Spectroscopy) experiments are presented. The performance characteristics of a supercapacitor are thoroughly analyzed in terms of losses and available energy to select the optimal product. The validity of the proposed criteria is demonstrated through the computer simulations and experiments on a fuel cell vehicle using a supercapacitor module with the FTP-72 urban dynamometer driving schedule.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2425-2430
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• 2009

Dye-sensitized solar cell(DSC) is composed of a dye-adsorbed nanoporous $TiO_2$ layer on fluorine-doped tin oxide(FTO) glass substrate, electrolyte, and platinium doped counter electrode. Among these, a dye-absorbed nanoporous $TiO_2$ layer plays an important role in the performance of the DSC because the injected electrons from excited dye molecules move through this layer. And the condition of $TiO_2$ layer such as the morphology and thickness affects on the electron movement. Therefore, the performances and the efficiency of DSC change as the thickness of $TiO_2$ layer is different. Electrochemical Impedance Spectroscopy(EIS) is the powerful analysis method to study the kinetics of electrochemical and photoelectrochemical processes occurring in the DSC especially the injected electron movements. So we analyzed the DSCs with different $TiO_2$ thicknesses by using EIS to understand the influence of the $TiO_2$ thickness to the performance of the DSC clearly. Finally, we got the EIS analysis on the DSC with different $TiO_2$ thickness from the internal resistance of the DSC, the electron life time and the amount of dye molecules.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.99-100
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• 2015

본 논문은 Hybrid Electric Vehicle용 리튬이온배터리의 ECM (Equivalent Circuit Model) 선정 방법을 제안한다. 전기 회로를 구성하는 성분들의 특징을 분석하고, 그 결과와 EIS (Electrochemical Impedance Spectroscopy) 장비의 측정 결과를 참고하여 배터리를 모델링한다. 다양한 종류의 배터리에 이 방법을 적용하여 각 배터리에 적합한 ECM을 선정하고, 그 임피던스를 EIS 측정 결과에 비교하여 타당성을 검증한다. 또한, 기존에 제시된 ECM과 비교하여 정확도 개선을 평가한다.