• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.691-694
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• 2004

염료감응형 태양전지는 다공질 $TiO_2$ 전극막, 광감응형 염료, 전해질, 상대전극으로 구성된, 전기화학적 원리를 응용한 신형태양전지이다. 염료감응형 태양전지의 상대전극으로 주로 Pt가 사용되고 있는데 본 연구에서는 탄소나노튜브를 사용하여 상대전극으로서의 가능성을 조사하였다. 제조된 탄소나노튜브 상대전극은 cyclic voltammetry와 Impedance spectroscopy을 이용하여 전기화학적 특성을 측정하였다. 또한 탄소 나노튜브 상대 전극이 태양전지의 효율 및 그 특성에 미치는 영향을 알아보기 위하여 단위 셀 태양전지를 제조하여 단파장 하에서의 광전특성을 측정하고, 이를 바탕으로 탄소나노튜브의 상대전극으로서의 가능성을 제시하였다.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.692-695
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• 2003

Generally, photovoltaic system is composed with several solar cell modules. For increasing power of photovoltaic systems, serial and parallel connection needed. A Desirable characteristic of a parallel supply system is that individual converters share the load current equally and stably. The current sharing(CS) can be implemented using two approaches. The first one, known as a droop method, relies on the high output impedance of each converter. and The second approach, known as active current-sharing techniques. In this paper, using droop method at parallel connection with it's convenience and simplicity.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.9-17
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• 2019

Sun power generation systems which use large capacity centralized inverters have loss of power generation due to cloud and building shadows, pollution, cell deterioration, etc. To minimize loss of power generation, decentralized solar power systems using multiple micro-inverters are being proposed as an alternative. A distributed solar power system consisting of a system-connected system uses power line communication to collect data from the micro-inverters. Power line communication has the advantage of using power lines without separate lines for data transmission, but in distributed solar power generation systems that use a large number of micro-inverters, the bit error rate is less reliable due to the phenomenon caused by limited transmission power, high load interference and noise, variable signal attenuation, and impedance characteristics. So we proposed wireless intelligent controller for micro-inverter that is used to build distributed solar power systems. and we design and implement that. Further, the proposed wireless intelligent controller for micro-inverter was used to establish a small-volume solar power plant to check its function and operation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.4
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• pp.139-143
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• 2005

For application of carbon nano-tube (CNT) as a counter electrode materials of dye-sensitized solar cell (DSSC), the electrochemical behavior of CNT electrode was studied, employing cyclic-voltammetry (C-V) and impedance spectroscopy. Fabrication of CNT-paste and formation of CNT-counter electrode for characteristic measurement have been carried out using ball-milling and doctor blade process, respectively. Unit cell for measurements was assembled using Pt electrode, CNT electrode, and iodine-embedded electrolyte. Field emission-scanning electron microscopy (FE-SEM) was used for structural investigation of CNT powder and electrode. Sheet resistance of electrode was measured with 4-point probe method. Electrochemical properties of electrode, C-V and impedance spectrum, were studied, employing potentiogalvanostat (EG&G 273A) and lock in amplifier (EG&G 5210). As a results, the sheet resistance of CNT electrode is almost similar to that of F-doped SnO2 (FTO) coated glass substrate as approximately 10 ohm/sq. From C-V and impedance spectroscopy measurements, it was found that CNT electrode has high reaction rate and low interface reaction resistance between CNT surface and electrolyte. These results provides that CNT electrode were superior to that of conventional Pt electrode. Particularly, the reaction rate in the CNT electrode is about thrice high than Pt electrode. Therefore. CNT electrode is to be good candidate material for counter electrode in DSSC.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.467-470
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• 2009

A novel 8 V DC power source with an external series-parallel connection of 50 Dye-Sensitized Solar Cells(DSSCs) has been proposed. One DSC has the optimized length to width ratio of $5.2{\times}2.6$ cm and an active area 8 $cm^2$($4.62{\times}1.73$ cm) which attained a conversion efficiency of 4.2%. From the electrochemical impedance spectroscopic analysis, it was found that the resistance elements related to the Pt electrode and electrolyte interface behave like that of diode and the series resistance corresponds to the sum of the other resistance elements. In addition, the TEMoo mode pulsed Nd:YAG laser beam is used to improve the incident photon to current efficiency(IPCE) of DSSC. From this result, this novel 8V-0.38A DC power source shows stable performance with an energy conversion efficiency of about 4.5% under 1 sun illumination(AM 1.5, Pin of 100 $mW/cm^2$).

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.160-160
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• 2013

Dye-sensitized solar cells (DSSCs) have attracted much attention because of their moderate light-to-electricity conversion efficiency, easy fabrication, and low cost. At present, platinum (Pt) is used as a counter electrode in DSSCs. However, it is found that Pt dissolves in iodide electrolyte solutions and creates chemical compound such as PtI4 and H2PtI6. Carbon based materials are one of candidates for a counter electrode of DSSCs. We prepare two types of graphite oxides by different chemical treatments; original graphite oxide, hydrazine treated graphite oxide. Each graphite oxide and magnesium nitrate dispersed in deionized water are prepared as solutions for electrophoretic deposition (EPD). Each graphite oxide electrode is deposited on fluorine-doped tin oxide (FTO) substrate by EPD method. Structural and electrochemical properties of each electrode are investigated by field-emission scanning electron microscopy and electrochemical impedance spectroscopy, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.53.2-53.2
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• 2011

Dye-sensitized solar cells(DSSCs) have been recognized as an alternative to the conventional p-n junction solar cells because of their simple fabrication process, low production cost, and transparency. A typical DSSC consists of a transparent conductive oxide (TCO) electrode, a dye-sensitized oxide semiconductor nanoparticle layer, liquid redox electrolyte, and a Pt-counter electrode. In dye-sensitized solar cells, charge recombination processes at interfaces between coducting glass, $TiO_2$, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. A layer of ZTO thin film less than ~200nm in thickness, as a blocking layer, was deposited by DC magnetron sputtering method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells(DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte ($I^-/I_3^-$). The presented DSCs were fabricated with working electrode of Ga-doped ZnO glass coated with blocking ZTO layer, dye-attached nanoporous $TiO_2$ layer, gel electrolyte and counter electrode of Pt-deposited GZO glass. The effects of blocking layer were studied with respect to impedance and conversion efficiency of the cells.

• Journal of Electrochemical Science and Technology
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• v.9 no.4
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• pp.308-319
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• 2018

Single step electrodeposition of $Cu_2ZnSnS_4$ (CZTS) for solar cell applications was studied using an aqueous thiocyanate based electrolyte. The sodium thiocyanate complexing agent was found to decrease the difference in the deposition potential of the elements. X-ray diffraction analysis of the samples indicates the formation of kesterite phase CZTS. UV-vis studies reveal the band gap of the deposits to be in the range of 1.2 - 1.5 eV. The thickness of the deposit was found to decrease with increase in pH of the electrolyte. Nearly stoichiometric composition was obtained for CZTS films coated at pH 2 and 2.5. I-V characterization of the film with indium tin oxide (ITO) substrate in the presence and the absence of light source indicate that the resistance decrease significantly in the presence of light indicating suitability of the deposits for solar cell applications. Results of electrochemical impedance spectroscopic studies reveal that the cathodic process for sulfur reduction is the slowest among all the elements.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.3
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• pp.289-296
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• 2014

Here, we have studied the effect of water added electrolyte on the photovoltaic performance of dye-sensitized solar cells (DSSCs). It was found that open-circuit voltage ($V_{oc}$) increased and short-circuit current density ($j_{sc}$) decreased with the increase of the amount of added water in the electrolyte of the DSSCs. Electrochemical impedance spectroscopy (EIS) study showed that the electrolyte with added water shifted the dye loaded $TiO_2$ conduction band upward that eventually increased $V_{oc}$ of the cells. On the other hand, the upward shift of $TiO_2$ conduction band decreased the driving force for the electron injection from the lowest unoccupied molecular orbital (LUMO) of the dye molecules to the conduction band of $TiO_2$ that resulted in decreased $j_{sc}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1792-1797
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• 2013

Recently, due to the excessive use of fossil fuels, many studies about the fossil fuels such as solar and fuel cell energy source are progressing. Fuel cell system has high energy conversion efficiency. Also, fuel cell system is environmentally friendly system because the carbon emission is almost not occur. Therefore, the fuel cell system is considered as the core technology of in the fields of the future energy and environmental. Fuel cell system has an effect on distribution power system because another power source of other than large power plants. So, fuel cell system can be reason of power quality in the power system. In this paper, we constructed the system for an assessment on Islanding. The system is composed with power source, Impedance coordination load and linear load, fuel cell system. we are performed assessment on voltage and power quality in customer and the distributed power system during the Islanding of residential fuel cell system. In addition, no change in the impedance of power system, we made a islanding condition only using the actual load, As a variation of generation and load current under islanding, an analysis results based on assessment system showed that the power qualities of distribution system became more aggravation as effect of voltage sag and voltage swell phenomena.