• Journal of Energy Engineering
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• v.27 no.3
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• pp.1-9
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• 2018

In this study, the outdoor evaluation test was performed to characterize the highly-reflective artificial grass to be used for bifacial photovoltaic (PV) power generation system. The 60-cell n-type Si monofacial and bifacial PV modules were employed, where two types of bifacial modules were equipped with split-type and box-type junction boxes, respectively. The results showed that the split-type junction box improved the rear-side power production and thus energy yield of bifacial module compared to the box-type junction box causing the shadow effect. Highly-reflective artificial grass achieved relatively high albedo of 0.18, and excellent bifacial gain of 33%, compared to conventional artificial grass with an albedo of 0.14-0.15, and bifacial gain of 29-30%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4733-4739
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• 2012

While traditional two-axis tracking systems with double sensors had been using two sensors to control azimuth and elevation angle of the sun so that a solar cell module would make a normal line with the sun, this paper proposed a new two-axis system that can achieve the same performance with only one sensor in it. It is Two-axis tracking system that control azimuth and elevation to control to be reduced for solar cell module as proposed tracking system uses 1 sensors and the sun always forms normal. Two-axis tracking system of one sensor method that propose in paper that could reduce electric power consumption and sees than fixed type preventing action and the most efficient driving and needless drive could confirm that generation efficiency of about 23 [%] increases. To heighten efficiency of solar cell doing to receive more sunlights chasing the sun, done tracking device have proceeded a lot of studies in large size way. Therefore, is expected that will do big part in the sun tracking supply through utility study about persistent generation efficiency constructing monitoring system of the sun tracking of this paper.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.89-91
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• 2007

In this paper, a remote monitoring system of wind-photovoltaic hybrid generation system using mobile phone and internet has been developed. Many kinds of data can be acquired, analyzed and saved automatically by this system. The hybrid system is composed of 1[kW] PV with DC/DC converter, battery banks and 5[kW] wind power system with power inductor and AC/DC converter. In addition, wind monitoring sensors, voltage and current meters, current transformers and potential transformers are used as accessory instruments. All of these signals are fed into DAQ (Data Acquisition) board after converting the data which have been processed by many types of converters, dividing circuits and signal conditioning circuits. These data can not only be displayed on a computer, transmitted using the server program to remote computer and saved on a computer as a file day by day but also be sent as a CDMA message. The monitored-data can be downloaded, analyzed and saved from server program in real-time via mobile phone or internet at a remote place. All of the programs were designed with LabVIEW software.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.196-200
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• 2004

A guard lamp system has been installed at the PV positive center, located at Gwangju in Korea. Digital environment that is represented to internet is displacing business way of industry and business achievement way with the fast speed being giving great change on life whole, improve existence business process utilizing internet and Web connection technology, information superhighway to tradition industrialist manufacture and e-transformation's propulsion that wish to maximize productivity and administration efficiency is spread vigorously. In this paper, we wish to accomplish generation equipment's heighten stability and believability through remote monitoring and control of guard lamp system. This paper describes the design of the monitoring system for the sensing data and indirect controlling of the guard lamp system. Most of the conventional monitoring systems depend on the special hardware and software. The essential design of monitoring system is to provide the convenience for the user and the portability for the system. In order for the system to fulfill its requirements, it was designed using Labview GUI facility based on the Windows 2000 environment of IBM PC compatible and Add-on card based on the TCP/IP protocol. Advantage of the monitoring system are a personnel expenses curtailment effect, of the place restriction and unmanned system of the generation plants, etc..

• Journal of the Korea Convergence Society
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• v.2 no.2
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• pp.35-45
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• 2011

Recently, with the increasement of the interest about global warming, pollutions, and so on, a number of distributed generations(DGs) such as photovoltaic(PV) and wind power(WP), are interconnected with distribution systems. However, installing of DGs makes power flow changes such as directions, one-direction to bi-direction, and increasing/decreasing of fault current. Therefore, it may cause the critical problems. This paper proposes an evaluation algorithm for bi-directional protection coordination and presents an evaluation system for protection coordination based on this algorithm. Additionally, the result shows that the existing method may cause critical problems, and also the effectiveness of proposed method is verified.

• Current Photovoltaic Research
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• v.6 no.1
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• pp.21-26
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• 2018

Beside several advantages, the PV power generation as a clean energy source, is still below the supply level due to high power generation cost. Therefore, the interest in fabricating low-cost thin film solar cells is increasing continuously. $Cu_2O$, a low cost photovoltaic material, has a wide direct band gap of ~2.1 eV has along with the high theoretical energy conversion efficiency of about 20%. On the other hand, it has other benefits such as earth-abundance, low cost, non-toxic, high carrier mobility ($100cm^2/Vs$). In spite of these various advantages, the efficiency of $Cu_2O$ based solar cells is still significantly lower than the theoretical limit as reported in several literatures. One of the reasons behind the low efficiency of $Cu_2O$ solar cells can be the formation of CuO layer due to atmospheric surface oxidation of $Cu_2O$ absorber layer. In this work, atomic layer deposition method was used to remove the CuO layer that formed on $Cu_2O$ surface. First, $Cu_2O$ absorber layer was deposited by electrodeposition. On top of it buffer (ZnO) and TCO (AZO) layers were deposited by atomic layer deposition and rf-magnetron sputtering respectively. We fabricated the cells with a change in the deposition temperature of buffer layer ranging between $80^{\circ}C$ to $140^{\circ}C$. Finally, we compared the performance of fabricated solar cells, and studied the influence of buffer layer deposition temperature on $Cu_2O$ based solar cells by J-V and XPS measurements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.710-720
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• 2009

The Future Generation Networks(FGNs) are proposed to integrate various heterogeneous access technologies, and further expected to support both vertical and seamless handovers. In this motivation, the IEEE 802.21 specifies Media Independent Handover(Mlli) services to enhance the mobile user experience by optimizing handovers between heterogeneous access networks. Additionally, Fast handover for MIPv6(FM1Pv6) is introduced to provide transparent host mobility and to improve handover performance by reducing handover delay as well. This paper focuses on the coordination of FMIPv6 and MIH, and introduces an enhanced mobility management framework suited for FGN. This novel framework replaces handover signaling messages used in wireless networks with novel MIH messages and local primitives. Moreover, Serving Access Router(SAR) performs most of handover processes instead of Mobile Node(MN). Therefore, the proposed mobility management framework reduces handover latency, packet loss, and signaling overhead significantly. We further evaluate the performance of the proposed framework by using both numerical analysis and network simulations.

• Journal of Hydrogen and New Energy
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• v.27 no.1
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• pp.114-120
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• 2016

This paper describes generating efficiency characteristics of the double acting Stirling engine/generator for domestic small-scale CHP (Combined Heat and Power) system. In small distributed generation applications, Stirling engine has competition from fuel cell, microturbine and etc. In order to be economical in the applications, a long life with minimum maintenance is generally required. Free piston Stirling engine (FPSE) has no crank and rotating parts to generate lateral forces and require lubrication. Double acting Stirling engine/generator has one displacer and two power piston which are supported by flexure springs. Two power pistons oscillate with symmetric displacement and are connected with moving magnet type linear generators for power generation from PV work. In experiments, 1 kW class double acting free piston Stirling engine/generator is fabricated and tested. Heat is supplied to hot end of engine by the combustion of natural gas and converted to electric power by linear generators which are assembled with power pistons. The electric parameters such as voltage, current and phase are measured with for variable flow rate of fuel gas. Especially, generating efficiency of FPSE is measured with three different measurement methods. Generating efficiency of the double acting Stirling engine/alternator is about 24%.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.292-297
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• 2005

This paper proposes a simple MPPT control scheme of a Current-Control-Loop Error system Based that can be obtains a lot of advantage to compare with another digital control method, P&O and IncCond algorithm, that is applied mostly a PV system. An existent method is needed an expensive processor such as DSP that calculated to change the measure power of a using current and voltage sensor at the once. Therefore, it is applied a small home power generation system that required many expenses. But, a proposed method is easy to solve the cost reduction and power unbalance problems that it is used by control scheme to limit error of a current control of common sensor. This proposed algorithm had verified through a simulation and an experiment on battery charger using PIC that is the microprocessor of a low price.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.517-518
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• 2006

본 논문은 태양광과 풍력, 축전지 시스템으로 구성된 계통연계형 복합 분산전원 시스템의 구성과 실험 결과를 제시한다. 본 논문에서 제시하고자하는 계통연계형 태양광-풍력-축전지 복합 분산전원 시스템은 태양광 발전 시스템과 풍력 발전 시스템을 에너지원으로 사용하였으며 에너지 저장장치로는 축전지 시스템을 사용하였다. 태앙광 발전 시스템과 풍력 발전 시스템, 축전지 시스템은 모두 공통 직류단에 연결되어 있으며 계통과 연계운전을 위한 계통연계 인버터 시스템을 공통 직류단과 계통 연계점 사이에 적용하여 연계점의 출력을 제어하였다. 또한 분산전원 통합제어 시스템을 개발하여 전체 복합 분산전원 시스템의 출력과 각 모듈의 상태를 감시, 제어하는 기능을 하도록 하였다. 개발된 복합 분산전원 시스템에 전력 평준화 알고리즘을 적용한 실험 결과의 제시를 통해 제작된 시스템과 전력 평준화 알고리즘의 유용성을 검증하였다. 본 논문에서 제시된 복합 분산전원 시스템은 복수의 에너지원을 이용하므로 전력공급의 신뢰도를 향상시킬 수 있어 상용전력이 공급되지 않는 도서지역 등에 단독 운전용으로 적용이 가능하다.