• Journal of Power Electronics
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• v.13 no.2
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• pp.313-321
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• 2013

This paper describes the operation analysis results of a communication-based DC micro-grid using a hardware simulator developed in the lab. The developed hardware simulator is composed of distributed generation devices such as wind power, photovoltaic power and fuel cells, and energy storage devices such as super-capacitors and batteries. Whole system monitoring and control was implemented using a personal computer. The power management scheme was implemented in a main controller based on a TMS320F28335 chip. The main controller is connected with the local controller in each of the distributed generator and energy storage devices through the communication link based on a CAN or an IEC61850. The operation analysis results using the developed hardware simulator confirm the ability of the DC micro-grid to supply the electric power to end users.

• Journal of Magnetics
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• v.19 no.3
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• pp.295-299
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• 2014

Recently, module-integrated converter (MIC) research has shown interest in small-scale photovoltaic (PV) generation. The converter is capable of efficient power generation. In this system, the high frequency transformer should be made compact, and demonstrate high efficiency characteristics. This paper presents a core structure optimization procedure to improve the efficiency of a high frequency transformer of compact size. The converter circuit is considered in the finite element analysis (FEA) model, in order to obtain an accurate FEA result. The results are verified by the testing of prototypes.

• Journal of Climate Change Research
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• v.8 no.1
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• pp.21-30
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• 2017

Recently, There has been much discussed about unused space. This space can be used in a variety of ways. Utilizing it as a facility, craft shop, and utilizing renewable energy generation facilities. Especially, in terms of climate change should be supplied renewable energy. Renewable energy needs to be developed in terms of responding to climate change, and the recent Paris agreement is also emphasizing the importance of renewable energy. In particular, renewable energy needs to be widely disseminated. And renewable energy is limited space. In this regard, idle land can provide opportunities for securing new renewable energy generation facilities. The introduction of new and renewable energy facilities in idle space can enhance the self-sufficiency rate of the local community, which is significant in terms of responding to climate. In this study, to investigate the possibility of utilizing a unused space for a photovoltaic power generation facility, we investigated the amount of electricity which could be generated through photovoltaic power generation, and the economic effects, using a RETScreen model. The results showed that 9,738 MWh of power can be generated and that $4,540tCO_2eqcan$ be saved. Regarding the economic effect, the net present value of the facility was shown to be 2,247,389,020 KRW. As the net present value was shown to be positive, we believe that the installation of a photovoltaic power generation facility in an unused space would have a positive economic effect. We found the net present value following the fluctuation of the SMP price to be positive, though there was some variation. However, as the economic efficiency was shown to be low because the net present value in relation to the maintenance costs was negative, we believe that maintenance costs must be taken fully into account when evaluating economic efficiency. In particular, as subsidies can be used to cover maintenance costs which must be factored into photovoltaic power generation, we believe that photovoltaic power generation can have an economic effect. Because spaces not currently in use can have a positive economic effect as renewable energy power generation facilities, and can also contribute to the reduction of greenhouse gas emissions, unused spaces are thought to greatly help local governments to cope with climate change as well as reinforcing their related capabilities. We believe our study will help local governments with decisions relating to unused real estate utilization in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1353-1362
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• 2014

In recent years, numerous environmental problems associated with the excessive use of fossil fuel are taking place. For an alternative energy resource, the importance of renewable energy and the demands of facilities to generate renewable energy are continuously rising. To satisfy such demands, a large number of photovoltaic energy generation structures are constructed and planned with large scale. However, because these facility zones are mostly constructed on land, some troubles are occurred such as rising of construction cost due to the cost of land use, environmental devastation, etc. To solve such problems, the floating type photovoltaic energy generation system using FRP members have been developed in Korea. FRP members are recently available in civil engineering applications due to many advantages such as high strength, corrosion resistance, light weight, etc. and they are suitable to fabricate the floating structures because of their material properties. In this study, the analytical and experimental investigations to evaluate the structural performance of floating PV generation structure and SMC FRP vertical member which is used to fabricate the structure were conducted. The static and dynamic performances of floating PV generation structure are evaluated through the FE analysis and the experiment, respectively. Moreover, the structural safety evaluation and buckling analysis of SMC FRP vertical compression member are also conducted by the FE analysis, and the structural behavior of SMC FRP member under compression and pullout is investigated by the experiments. From this study, it was found that the structural system composed of pultruded FRP and SMC FRP members are safe enough to resist externally applied loads.

• Journal of Power Electronics
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• v.9 no.2
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• pp.320-333
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• 2009

A Photovoltaic (PV) system's power output varies with the change of climate. Frequency deviations, tie line voltage swings are caused by the varying PV power when large PV power from several PV systems is fed in the utility. In this paper, to overcome these problems, a simple coordinated control method for smoothing the variations of combined PV power from multiple PV systems is proposed. Here, output power command is formed in two steps: central and local. Fuzzy control is used to produce the central smoothing output power command considering insolation, variance of insolation and absolute average of frequency deviation. In local step, a simple coordination is kept between the central power command and the local power commands by producing a common tuning factor. Power converters are used to achieve the same output power as local command power employing PI control law for each of the PV generation systems. The proposed method is compared with the method where conventional Maximum Power Point Tracking (MPPT) control is used for each of the PV systems. Simulation results show that the proposed method is effective for smoothing the output power variations and feasible to reduce the frequency deviations of the power utility.

• KIEAE Journal
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• v.7 no.6
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• pp.17-22
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• 2007

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This paper compares the experimental performance of two different types of air type PV/T collector units: the base case of a collector unit with 10cm gap for forced ventilation and the other unit with copper pin attached to PV module to enhance its thermal performance. The experimental results shows that the base case unit had the overall efficiency of 41.9% and the improved unit with copper pin attached to PV module had 50.1% efficiency. For these air type PV/T units, the forced ventilation of the air space improved the electrical performance as well as the thermal performance.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.179-184
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• 2012

This research on building Integrated Photovoltaic System replacing windows and doors with amorphous silicon thin film PV windows and doors installing same exact mount on Mock-up. The windows and doors should be installed in different angle and bearing so that we can analyse the amount of electricity from them. The objective of the research is to evaluate and investigate the relationship between factors(intensity of solar radiation, PV window surface temperature, incidence angle, and sky conditions) that affects performance of PV window and performance. The range and method of this research is to establish monitoring system and analysis the data from the monitoring system to evaluate the performance of PV windows that have thin film of solar battery. We should evaluate the insolation according to the position of PV window, output, and surface temperature according to months and seasons so that we can figure out the relationship between these. And we should investigate the relationship between performance and efficiency according to incidence angle and sky condition so that we can figure out the correlation between factors and performance.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1359-1361
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• 2003

As the maximum power operating point(MPOP) of Photovoltaic(PV) power generation systems changes with changing atmospheric conditions such as solar radiation and temperature, an important consideration. In the design of efficient PV system is to track the MPOP correctly. Many maximum power point tracking(MPPT) techniques have been considered in the past, however, techniques using microprocessors with appropriate MPPT algorithms are favored because of their flexibility and compatibility with different PV arrays. Although the efficiency of these MPPT algorithms is usually high, it drops noticeably in case of rapidly changing atmospheric conditions. This pager proposed a new MPPT algorithm based on perturb & observe(P&O) algorithm with experiment. The results shows that the new P&O algorithm has successfully tracked the MPOP, even in case of rapidly changing atmospheric conditions, and has higher efficiency than ordinary algorithms.

• KIEAE Journal
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• v.17 no.1
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• pp.77-82
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• 2017

In power supply systems for urban areas, issues such as a progressive tax have escalated recently. In this regard, photovoltaic power generation, which is appraised as an alternative power generation system, is drawing attention increasingly for its high stability and applicability to existing infrastructure. This study assessed the realistic feasibility of photovoltaic power generation and also analyzed the economic benefits expected when it is linked with green roof, which is likely to promote ecological functions in urban areas, based on the Seoul solar map, RPS, and actual monitoring data. The economics analysis of 30kW photovoltaic power generation applied with the monthly average horizontal solar radiation of six grades in the Seoul solar map showed that positive NPV was up to grade 4, while grade 5 or poorer showed negative NPV and indicated that it is difficult to assure appropriate feasibility. Compared with non-afforestation, when green roof was applied, monthly average power improvement efficiency was 7.2% at highest and 3.7% at lowest based on yearly actual monitoring data. The annual average was 5.3%, and the efficiency was high relatively in summer, including September and November. As for the economic benefits expected when 30kw photovoltaic power generation is combined with green roof based on the average horizontal solar radiation of grade 1 in the Seoul solar map, SP has improved 0.2 years to 7.4 years, and EP has improved 0.5 years to 8.3 years.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.207-217
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• 2018

Recently, the importance of energy demand management, particularly peak load control, has been increasing due to the policy changes of the Second Energy Basic Plan. Even though the installation of distributed generation systems such as Photovoltaic and energy storage systems (ESS) are encouraged, high initial installation costs make it difficult to expand their supply. In this study, the power consumption of a university building was measured in real time and the measured power consumption data was used to calculate the optimal installation capacity of the Photovoltaic and ESS, respectively. In order to calculate the optimal capacity, it is necessary to analyze the operation methods of the Photovoltaic and ESS while considering the KEPCO electricity billing system, power consumption patterns of the building, installation costs of the Photovoltaic and ESS, estimated savings on electric charges, and life time. In this study, the power consumption of the university building with a daily power consumption of approximately 200kWh and a peak power of approximately 20kW was measured per minute. An economic analysis conducted using these measured data showed that the optimal capacity was approximately 30kW for Photovoltaic and approximately 7kWh for ESS.