• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.85-87
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• 2009

Despite the success of $Cu(In,Ga)Se_2$ (CIGS) based PV technology now emerging in several industrial initiatives, concerns about the cost of In and Ga are often expressed. It is believed that the cost of those elements will eventually limit the cost reduction of this technology. one candidate to replace CIGS is $Cu_2ZnSnSe_4$ (CZTSe), fabricated by co-evaporation technique. Effects of substrate temperature of $Cu_2ZnSnSe_4$ absorber layer on the performance of thin films solar cells were investigated. As substrate temperature increased, the grain size of $Cu_2ZnSnSe_4$ films increased presumably. At a optimal condition of substrate temperature is $320^{\circ}C$, the solar cell shows a conversion efficiency of 1.79% with $V_{OC}$ of 0.213V, JSC of $16.91mA/cm^2$ and FF of 49.7%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.997-999
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• 2012

Digital X-ray image detector is widely used for radiodiagnosis. Amorphous selenium has been received attention as one of the major material that confirmed photoconductor of direct methode detector. We analysis the photocurrent using 2-dimensional device simulator when blue-ray (${\lambda}=486nm$) is irradiated and high voltage is biased. We evaluate electron-hole generation rate, electron-hole recombination rate, and electron/hole distribution in the amorphous selenium. This simulation methode is helpful to the analysis of digital X-ray image detector. We expect that many applications will be developed in digital X-ray image detector using 2-dimensional device simulator.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.73-80
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• 1989

The image sensitive PbO photoconductive films were fabricated ar several deposition conditions such as $O_2$ gas pressure, deposition rate, and substrate temperature. And the effects of these deposition condition on the structural and electrical properties of them were investigated with the aid of scanning electron photomicrographs. X-ray diffraction patterns, and current-valtage chatacteristics. The results show that when PbO film has red tetragonal structure and its dominant orientations are <110> and <010> direction, photocurrent-darkcurrent ratio and light transfer ratio are increase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.704-712
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• 2016

Recently, the installation of photovoltaic (PV) systems has been increasing due to the worldwide interest in eco-friendly and infinitely abundant solar energy. However, the output power of PV systems is highly influenced by the surrounding environment. For instance, a string of PV systems composed of modules in series may become inoperable under cloudy conditions or when in the shade of a building. In other words, under these conditions, the existing control method of PV systems does not allow the string to be operated in the normal way, because its output voltage is lower than the operating range of the grid connected inverter. In order to overcome this problem, we propose a new control method using a DC-DC voltage regulator which can compensate for the voltage of each string in the PV system. Also, based on the PSIM S/W, we model the DC-DC voltage regulator with constant voltage control & MPPT (Maximum Power Point Tracking) control functions and 3-Phase grid connected inverter with PLL (Phase-Locked Loop) control function. From the simulation results, it is confirmed that the present control method can improve the operating efficiency of PV systems by compensating for the fluctuation of the voltage of the strings caused by the surrounding conditions.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.17-23
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• 2017

Optical current sensors are suitable for operation in high voltage and high current environments such as power plants due to they are not affected by electromagnetic interference and have excellent insulation characteristics. However, as they operate in a harsh environment such as large temperature fluctuation and mechanical vibration, high reliability of the sensor is required. Therefore, many groups have been working on enhancing the reliability. In this work, an integrated optical current sensor incorporating polarization-rotated reflection interferometer is proposed. By integrating various optical components on a single chip, the sensor exhibits enhanced stability as well as the solution for low-cost optical sensors. Using this, we performed the characterization for the actual field application. By using a large power source, the current of 0.3 kA~36 kA was applied to the photosensor and the linear operation characteristics were observed. The error of the sensor was within $0{\pm}.5%$. Even when operating for a long time, the error range of the sensor was kept within $0{\pm}.5%$. In addition, the measurement of the frequency response over the range of 60 Hz to 10 kHz has confirmed that the 3-dB frequency band of the proposed OCT is well over 10 kHz.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.846-849
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• 1991

This paper reports the principle, system confiquration, test results of optical voltage sensor using quartz pockels cell. The Pockels effect of quartz material is used for designing optical voltage sensor. The quarts material has very high half-wave voltage, so, it can be applied to measure high voltage level. Experimental results show that the optical voltage sensor has excellent linear characteristics within the applied AC voltage of 1200V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.216-220
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• 1994

Polycrystalline CdS films have been prepared by coating a slurry, which consisted of CdS, 11w% CdCl$_2$ and appropriate amount of propylene glycol, on glass substrate and glass substrate coated with indium tin oxide(ITO) followed by sintering in a nitrogen atmosphere. CdTe slurries consisting of Te powder and Cd powder were coated on the sintered CdS films and ITO/CdS films and were sintered in nitrogen to prepare sintered CdS/CdTe and ITO/CdS/CdTe solar cells. The value of fill factor increased due to low series resistance and open circuit voltage decreased due to low shunt resistance in the ITO/CdS/CdTe solar cells.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.6
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• pp.48-56
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• 1989

Contact-type linear image sensors for facsimile have been fabricated by means of rf glow discharge decomposition method of silane. The dependence of their electrical and optical properties on rf power, $SiH_4$ flow rate, ambient gas pressure, $H_2SiH_4$ ratio and substrate temperature are described. The a-Si:H monolayer demonstriated photosensitivity of 0.85 and $I_{ph}/I_d$ ratio of 100 unger 100 lux illumination. However, this monolayer has relatively high dark current due to carrier injection from both electrodes, resulting in low $I_{ph}/I_{dd}$ ratio. To suppress the dark current we have fabricated $SiO_2/i-a-Si:H/p-a-Si:H:B$ multilayer film with blocking structure. The photocurrent of this multilayer sensor with 6 V bias became saturated ar about 20nA under 10 lux illumination, while the dark current was less than 0.2 nA. Moreover, the spectral sensitivity of the multilayer film was enhanced for short wavelength visible region, compared with that of the a-Si:H monolayer. These results show that the fabricated photocon-ductive film can be used as the linear image sensor of the facsimile.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.918-923
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• 2002

In this work, CdTe films were deposited on CdS/ITO/glass substrate by a close spaced sublimation (CSS) method. A $Cu_2$Te layer was deposited on the CdTe film by evaporating $Cu_2$Te powder. Then the samples were annealed for p+ ohmic contact. TEM and XRD analysis showed that $CdTe/Cu_2$Te interface exhibited different forms with various annealing temperature. A good p+ ohmic contact was achieved when the annealing temperature was between $180^{\circ}C$ to $200^{\circ}C$. Best cell efficiency of 12.34% was obtained when post annealing temperature was $200^{\circ}C$ for 5 min. Thermal stress test of the CdS/CdTe cells with carbon back contact showed that the $Cu_2$Te contact was stable at $50^{\circ}C$ in $N_2$ and was slowly degraded at $100^{\circ}C$ in $N_2$. In comparison to the conventional carbon contact, the $Cu_2$Te contact showed a better thermal stability.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.106-112
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• 1989

In this paper, voltage and current measurement systems which utilize linear electrooptic and magnetooptic effects of BSO and ZnSe crystals are theoretically analyzed and experimented. In experiments, BSO voltage sensor has maximum 2% error within the applied voltage of 500V, and ZnSe current sensor has maximum 4% error within 1,000 A range. And temperature dependences of sensitivity for voltage and current in the temperature range from $-5^{circ}C\;to\;60^{circ}$C are measured +1.8% and 2.73%, respectively.