• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.79-89
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• 2006

Particularly the photovoltaic systems are preferred because the output is extracted to the useful electric energy. However, the output characteristics of photovoltaic(PV) systems using solar cell or array depend on the weather conditions. The assistant equipment which emulates the solar cell characteristics that can be controlled arbitrarily by researcher is required to the researchers for reliable experimental data. To solve these problems, it is necessary to research a solar cell model of which output characteristics varied by setting the weather conditions such as insolation levels and temperatures. Therefore, this paper was presented that improved model which is based on interpolation model. To verified the improved model, it is confirmed using the simulation of MATLAB. Also, the experiment was performed by the characteristics of virtual implemented solar cell(VISC) system with the proposed solar cell model. It could be confirmed that there exists actual ewer within 5% between actual solar cell and VISC system.

• Journal of the Korea Institute of Military Science and Technology
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• v.1 no.1
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• pp.227-237
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• 1998

HgCdTe Is the most versatile material for the developing infrared devices. Not like III-V compound semiconductors or silicon-based photo-detecting materials, HgCdTe has unique characteristics such as adjustable bandgap, very high electron mobility, and large difference between electron and hole mobilities. Many research groups have been interested in this material since early 70's, but mainly due to its thermodynamic difficulties for preparing materials, no single growth technique is appreciated as a standard growth technique in this research field. Solid state recrystallization(SSR), travelling heater method(THM), and Bridgman growth are major techniques used to grow bulk HgCdTe material. Materials with high quality and purity can be grown using these bulk growth techniques, however, due to the large separation between solidus and liquidus line on the phase diagram, it is very difficult to grow large materials with minimun defects. Various epitaxial growth techniques were adopted to get large area HgCdTe and among them liquid phase epitaxy(LPE), metal organic chemical vapor deposition(MOCVD), and molecular beam epitaxy(MBE) are most frequently used techniques. There are also various types of photo-detectors utilizing HgCdTe materials, and photovoltaic and photoconductive devices are most interested types of detectors up to these days. For the larger may detectors, photovoltaic devices have some advantages over power-requiring photoconductive devices. In this paper we reported the main results on the HgCdTe growing and characterization including LPE and MOCVD, device fabrication and its characteristics such as single element and linear array($8{\times}1$ PC, $128{\times}1$ PV and 4120{\times}1$ PC). Also we included the results of the dewar manufacturing, assembling, and optical and environmental test of the detectors.

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.488-499
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• 2016

We present a design and optical simulation of a cost-effective hybrid daylighting/LED system composed of mixing sunlight and light-emitting diode (LED) illumination powered by renewable solar energy for indoor lighting. In this approach, the sunlight collected by the concentrator is split into visible and non-visible rays by a beam splitter. The proposed sunlight collector consists of a Fresnel lens array. The non-visible rays are absorbed by the solar photovoltaic devices to provide electrical power for the LEDs. The visible rays passing through the beam splitters are coupled to a stepped thickness waveguide (STW) by tilted mirrors and confined by total internal reflection (TIR). LEDs are integrated at the end of the STW to improve the lighting quality. LEDs’ light and sunlight are mixed in the waveguide and they are coupled into an optical fiber bundle for indoor illumination. An optical sensor and lighting control system are used to control the LED light flow to ensure that the total output flux for indoor lighting is a fixed value when the sunlight is inadequate. The daylighting capacity was modeled and simulated with a commercial ray tracing software (Lighttools^TM). Results show that the system can achieve 63.8% optical efficiency at geometrical concentration ratio of 630. A required accuracy of sun tracking system achieved more than ±0.5^o . Therefore, our results provide an important breakthrough for the commercialization of large scale optical fiber daylighting systems that are faced with challenges related to high costs.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.109-116
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• 2005

Wind power and photovoltaic(PV) systems are getting into the spotlight as substitute energy. But problem is happened stability by speed change of wind and the power output of the sun's ray. The power output amount according to velocity of wind power system. System breakdown can happen at change of sudden velocity, typhoon and night. This paper shows a automatic tail safety brake controller based on feedback control using wind velocity. The operation of automatic tail safety controller verified by manual test. PV system is a energy change system by temperature of sun's ray and cell. Maximum power point tracking(MPPT) is used in PV systems to maximize the photovoltaic array output power. In existed PV system is low output and changeable DC voltage for boost and filtering the buck-boost converter use. But, this paper established deformed DC-DC converter. Changed Buck-boost converter's unlined output current to line output current using DC-DC converter. This is effect that reduce ripple of output current. Proved through an output waveform comparison experiment. Finally, tail safety brake controller is established to wind turbine system for stability elevation and DC-DC converter is established on PV system for stability output.

• Journal of agriculture & life science
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• v.46 no.5
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• pp.143-152
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• 2012

This study was performed to reduce the operating cost of a greenhouse by securing electric energy required for greenhouse operation. Therefore, it experimentally reviewed the performance analysis of photovoltaic system in terms of maximum amount of generated electric power based on the amount of horizontal solar radiation during daytime. That is to say, the maximum solar radiation at 300, 400, 500, 600, 700, 800 and 900 W. $m^{-2}$, respectively. The amount of momentary electric power of the photovoltaic system at any was about 970 W and we found that the momentary efficiency of the photovoltaic system that was used for this experiment was 97%. In the case of this system, we found that electric power will be generated when amount of horizontal solar radiation is more than 200 W. $m^{-2}$, at minimum. If the amount of horizontal solar radiation is increased, the maximum power generation is also increased. At that time, the maximum efficiencies were 30, 78, 86 and 90%, respectively. However, when the amount of insolation was about 800 W. $m^{-2}$, the maximum power generation tended to be lower than 700 W. $m^{-2}$. The efficiency which caused the maximum electric power was decreased to less than 97% of the momentary generated electric power. When the total amounts of horizontal solar radiation per day were 3.24, 8.10, 10, 90, 12.70, 14.33, 19.53 and $21.48MJ{\cdot}m^{-2}$ respectively, the total amounts of power energy were 0.03, 0.40, 3.60, 4.37, 4.71, 4.70 and 4.91 kWh. And it represented that the total amounts of power energy were either decreased or increased a bit on the border between some solar radiations. The temperature at the back of the array tended to be higher than the temperature at the front but it demonstrated an increased when the amount of solar radiation increased. In the case of this system, the performance of the module in terms of degradation has not been shown yet.

• Journal of the Korean Solar Energy Society
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• v.37 no.6
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• pp.69-77
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• 2017

The amount of solar irradiation obtained by a photovoltaic (PV) solar panel is the major factor determining the power generated by a PV system, and the array tilt angle is critical for maximizing panel radiation acquisition. There are three types of PV systems based on the manner of setting the array tilt angle: fixed, semi-fixed, and tracking systems. A fixed system cannot respond to seasonal solar altitude angle changes, and therefore cannot absorb the maximum available solar radiation. The tracking system continually adjusts the tilt angle to absorb the maximum available radiation, but requires additional cost for equipment, installation, operation, and maintenance. The semi-fixed system is only adjusted periodically (usually seasonally) to obtain more energy than a fixed system at an overall cost that is less than a tracking system. To maximize semi-fixed system efficiency, determining the optimal tilt angle adjustment schedule are required. In this research, we conducted a simulation to derive an optimal operation schedule for a semi-fixed system in Seoul, Korea (latitude $37.5^{\circ}$). We implemented a solar radiation acquisition model and PV genereation model on MATLAB. The optimal operation schedule was derived by changing the number of tilt angle adjustments throughout a year using a Dynamic Algorithm. The results show that adjusting the tilt angle 4 times a year was the most appropriate. and then, generation amount of PV system increased 2.80% compared with the fixed system. This corresponds to 99% compared to daily adjustment model. This increase would be quite valid as the PV system installation area increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5452-5457
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• 2012

It is saving material cost and construction cost by replacing conventional building materials, and It has advantages for aesthetic value. In the Europe, the United States, Japan and other country research about BIPV is actively being carried out and marketability is also being infinity expanding. Arch type PV systems efficiency characteristics is different depending on PV array's directly connection, parallel connection and arches angle, but is a lack of analysis on this nowadays. When the arch type PV system design up, they consider about aesthetic value and they didn't consider about generation efficiency. In this paper, we try to improve the efficiency through optimization of arch type PV system and estimation of the efficiency parameters of the arch type PV system, such as latitude, longitude, temperature, insolation, arch angle and each kind loss from system organization. For improving Arched PV system efficiency, proposed multiple control inverter system, and using simulation tool of Arched PV system "Solar pro", flat-plate type and many arch type PV system configuration the driving characteristics were compared and analyzed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.429-429
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• 2016

Organolead halide perovskite have attracted much attention over the past three years as the third generation photovoltaic due to simple fabrication process via solution process and their great photovoltaic properties. Many structures such as mesoporous scaffold, planar heterojunction or 1-D TiO2 or ZnO nanorod array structures have been studied to enhance performances. And the photovoltaic performances and carrier transport properties were studied depending on the cell structures and shape of perovskite film. For example, the perovskite cell based on TiO2/ZnO nanorod electron transport materials showed higher electron mobility than the mesoporous structured semiconductor layer due to 1-D direct pathway for electron transport. However, the reason for enhanced performance was not fully understood whether either the shape of perovskite or the structure of TiO2/ZnO nanorod scaffold play a dominant role. In this regard, for a clear understanding of the shape/structure of perovskite layer, we applied anodized aluminum oxide material which is good candidate as the inactive scaffold that does not influence the charge transport. We fabricated vertical one dimensional (1-D) nanostructured methylammonium lead mixed halide perovskite (CH3NH3PbI3-xClx) solar cell by infiltrating perovskite in the pore of anodized aluminum oxide (AAO). AAO template, one of the common nanostructured materials with one dimensional pore and controllable pore diameters, was successfully fabricated by anodizing and widening of the thermally evaporated Al film on the compact TiO2 layer. Using AAO as a scaffold for perovskite, we obtained 1-D shaped perovskite absorber, and over 15% photo conversion efficiency was obtained. I-V measurement, photoluminescence, impedance, and time-limited current collection were performed to determine vertically arrayed 1-D perovskite solar cells shaped in comparison with planar heterojunction and mesoporous alumina structured solar cells. Our findings lead to reveal the influence of the shape of perovskite layer on photoelectrical properties.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.386-389
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• 2006

BIPV(Building Integrated PV) system can expect dual effects that reduce expenses for establishment of PV system by adding new function as outer covering material of building expect producing the electricity. In case of PV(photovoltaic system) there are many generation differences according to the exterior environmental facts(solar cell array, design and installation condition of interactive inverter system). In this paper, we compared constitute factors of 3kW BIPV(solar cell module, inverter), operating characteristic and total system characteristic(utilization, generation efficiency, loss fact) and found out long time operating data using a watch instrumentations. By use of long time operating result, compare a totally operating characteristics, and we proposed a next building application of BIPV. BIPV system that is proposed in this paper, was established in Solar Energy research center of Chosun University, composed with system. The objective of this paper, is to provide a efficient BIPV design method through the considerations for the integration of PV system.

• Journal of Power Electronics
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• v.11 no.2
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• pp.179-187
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• 2011

This paper proposes a MATLAB Simulink simulator for photovoltaic (PV) systems. The main contribution of this work is the utilization of a two-diode model to represent a PV cell. This model is known to have better accuracy at low irradiance levels which allows for a more accurate prediction of PV system performance. To reduce computational time, the input parameters are reduced to four and the values of $R_p$ and $R_s$ are estimated by an efficient iteration method. Furthermore, all of the inputs to the simulator are information available on a standard PV module datasheet. The simulator supports large array simulations that can be interfaced with MPPT algorithms and power electronic converters. The accuracy of the simulator is verified by applying the model to five PV modules of different types (multi-crystalline, mono-crystalline, and thin-film) from various manufacturers. It is envisaged that the proposed work can be very useful for PV professionals who require a simple, fast and accurate PV simulator to design their systems.