• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.97-104
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• 2017

In the present industrial field, the demand for the development of the solar power source device and the charging device for the solar cell is gradually increasing. The solar charger is largely divided into a DC-DC converter that converts the voltage generated from the sunlight to a charging voltage, and a battery and a charger that are charged with an actual battery. The conventional charger topology is used either as a Buck converter or a Boost converter alone, which has the disadvantage that the battery can not always be charged to the desired maximum power as input and output conditions change. Although studies using a topology capable of boosting and stepping have been carried out, Buck-Boost converters or Sepic converters with relatively low efficiency have been used. In this paper, we propose a new Buck Boost combination power converter topology structure that can use Buck converter and Boost converter at the same time to improve inductor current ripple and power converter efficiency caused by wide voltage control range like solar charger.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.467-474
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• 2021

The renewable energy is known as eco-friendly energy to reduce the use of fossil fuel and decrease the environmental pollution due to exhaust gas. Targets of solar collector in domestic are usually acquisitions of hot water and hot air. System of air-heating collector is one of the technologies for obtaining hot air in cases of especially heating room and drying agricultural product. The purpose of this study is to investigate the characteristics of thermal flow such as relative pressure, velocity, outlet temperature and buoyancy effect in air-heating collector using solar heat. The flow field of air-heating collector was simulated using ANSYS-CFX program and the behaviour of hot air was evaluated with SST turbulence model. As the results, The streamline in air-heating collector showed several circular shapes in case of condition of buoyancy. Temperature difference in cross section of outlet of air-heating collector did not almost show in cases of buoyancy and small inlet velocity. Furthermore merit of air-heating collector was not observed in cases of inlet velocities. Even though it was useful to select condition of buoyancy for obtaining high temperature, however, it was confirmed that the trade off between high temperature of room and rapid injection of hot air to room could be needed through this numerical analysis.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_1
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• pp.967-976
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• 2023

Currently, with the thriving development in the field of solar energy, the widespread adoption of solar grid-connected power conversion systems is rapidly expanding. As the market continues to grow, the efficiency of solar power conversion systems is steadily increasing, while prices are rapidly decreasing. Photovoltaic panels often produce low output voltages, and Boost converters are commonly employed to elevate and stabilize these voltages. They are also utilized for implementing Maximum Power Point Tracking (MPPT), ensuring the full utilization of solar power generation. Recently, synchronous control techniques have been introduced, using controllable switching devices like Si IGBT or SiC MOSFET to replace the diodes in the original circuits. However, this has raised concerns related to costs. This paper offers a compromise solution, considering both the performance and economic factors of the converter. It proposes a hybrid high-efficiency synchronous converter structure that combines Si IGBT and SiC MOSFET. Additionally, the proposed topology has been practically implemented and tested, with results confirming its feasibility and cost-effectiveness.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.432-437
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• 2011

Recently, industry needs a new design of Czochralski(Cz) process for higher productivity with reasonable energy consumption. In this study, we carried out computational simulations for finding out a new optimal design of Cz process with variables which can be applied in real industry such as location of heater, shape of shield and crucible size. Objective process was Cz process which can be produced 8 inch diameter Si ingot for solar cell and we acquired an optimal design for higher productivity, low power consumption with stable production condition. For higher productivity we also change the crucible diameter from 22 inches to 24 inches with changing insulation thickness only because the process housing size could not be changed in industry.

• Current Photovoltaic Research
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• v.6 no.4
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• pp.124-132
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• 2018

The Korean electric power supply plan was prepared by greatly enhancing the environmental and safety with considering the economical efficiency of the electric equipment, the impact on the environment and the public safety. As a result, the fossil energy-based power generation sector is accelerating the paradigm shift to eco-friendly energy such as solar power and wind. Also the solar power industry is expected to grow into a super large-sized industry by converging the energy storage and electric vehicle industry. Generally, a levelized cost of electricity (LCOE) is used to calculate the power generation cost for different generation power generation efficiency, operating cost, and life span. In this paper, we have studied the future research and development direction of photovoltaic technology development for the era of massive utilization of photovoltaic solar power, and have studied the LCOE of major countries including China, USA, Germany, Japan and Korea. Finally we have reviewed USA and Japan research programs to reduce the LCOE.

• Current Photovoltaic Research
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• v.3 no.2
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• pp.45-49
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• 2015

In the past few decade's researchers, scientists, engineers of photovoltaic (PV) industry are working towards low cost high efficiency Si solar cells. Over the last decade the interest in back contact solar cell has been acquiring as well as a gradual introduction to industrial applications is increasing. As an alternative to conventional solar cells with a front and rear contact, the back-contact cells has remained a research topic. The aim of this work is to present a comprehensive summary of results incurred in the back contact back junction solar cells such as interdigitated back-contact (IBC), emitter wrap-through (EWT) and metallization wrap-through (MWT) over the years.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.3
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• pp.119-123
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• 2013

Most of the world's solar cells in photovoltaic industry are currently fabricated using crystalline silicon. Czochralski-grown silicon crystals are more expensive than multicrystalline silicon crystals. The future of solar-grade Czochralski-grown silicon crystals crucially depends on whether it is usable for the mass-production of high-efficiency solar cells or not. It is generally believed that the main obstacle for making solar-grade Czochralski-grown silicon crystals a perfect high-efficiency solar cell material is presently light-induced degradation problem. In this work, the substitution of boron with gallium in p-type silicon single crystal is studied as an alternative to reduce the extent of lifetime degradation. The diamond-wire sawing technology is employed to slice the silicon ingot. In this paper, the quality of the diamond wire-sawn gallium-doped silicon wafers is studied from the chemical, electrical and structural points of view. It is found that the characteristic of gallium-doped silicon wafers including texturing behavior and surface metallic impurities are same as that of conventional boron-doped Czochralski crystals.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.287.2-287.2
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• 2014

PV (photovoltaic) has becoming an important industry to invest due to its high robustness and require very little maintenance which goes a long time. Solar cell fabrication involves a few critical processes such as doping to make the N-type and P-type silicon, contact metallization, surface texturization, and anti-reflection coatings. Anti-reflection coating is a kind of surface passivation which ensures the stability, and efficiency of the solar cell. Thus, I will focus on the changes happen to the solar cell due to the reflectance and anti-reflection coating by PC1D. By using the PC1D (solar cell simulation program), I would analysis the effect of reflectance on the N-type cell. At last I will conclude the result regarding what I learned throughout this experiment.

• Electrical & Electronic Materials
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• v.11 no.11
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• pp.37-45
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• 1998

In this paper, present status of super high-efficiency tandem solar cells has been reviewed and key issues for realizing super high-efficiency have also been discussed. In addition, the terretrial R&D activities of tandem cells, in the New Sunshine Program of MITI(Ministry of International Trade and Industry) and NEDO(New Energy and Industrial Technology Development Organization) in Japan are reviewed briefly. The mechanical stacked 3-junction cells of monolithically grown InGaP/GaAs 2-junction cells and InGaAs cells have reached the highest efficiency achieved in Japan of 33.3% at 1-sun AM1.5. This paper also reports high-efficiency InGaP/GaAs 2-junction solar cells with a world-record efficiency of 26.9% at AM0, 28$^{\circ}C$ and radiation damage recovery phenomena of the tandem cell performance due to minority-carrier injection under light illumination or forward bias, which causes defect annealing in InGaP top cells. Future prospects for realizing super-high efficiency and low-cost tandem solar cells are also described.

• Solar Energy
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• v.18 no.4
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• pp.33-38
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• 1998

This paper reports the experimental results concerning the thermal performance of a freeze-protected direct solar water heating system. The direct system tested has been manufactured to prevent any breakage during harsh wintry conditions by specially designed riser and downcomer headers capable of relieving extra pressure due to freezing of water. The direct system tested has shown 10% improvement in its efficiency over that of a indirect type system using antifreeze as the heat transfer medium. It is felt that any direct system of its kind could galvanize the whole solar industry if further improvements are made to ensure its durability.