• Proceedings of the KIEE Conference
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• 2008.11b
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• pp.157-159
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• 2008

This paper summarizes the results of these efforts by offering a photovoltaic system structure in 50kW. The combination of photovoltaic system components are interconnected and system monitoring system will be summarized for the purpose of the increasing safety in this article. This paper describes configuration of utility interactive photovoltaic system which generated electric power supplies to dormitory. In order to installing the middle or large scale photovoltaic system, It must investigated the optimal design of system, compute quantity of power generation, economic rate of return and so on. In this paper represent 50kW utility photovoltaic system examination, developed simulation results and financial analysis. The performance of photovoltaic system has been evaluated, analyzed with simulation and financial analysis results. The results obtained in this research will be much useful to prior investigation for installing utility interactive photovoltaic system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.23-30
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• 2003

This paper analyzes the characteristic of utility connection type solar power generation system which it is available to connect the utility. And the operation characteristic of this system is compared and analyzed when it is operated in the real system. The constructional and operational problem were obtained by that result. Overcoming that defect is that finding the proper place to be well operated and to find the best place for getting the sunshine data. This method could increase the efficiency of the generation system. And more, current OS in operating system and monitoring management couldn't solve the problem so that improving OS and constructing data backup system should be implemented, This paper proposes the plan to solve that defect in the real system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.596-601
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• 2006

Because of insufficiency of energy resources and pollution of environment, it is necessary to develop alternative energy sources. Nuclear fission energy is used widely for source of electric Power but being restricted due to radioactivity problem. Nuclear fission is highlighted as the new generation of nuclear energy and researched worldwide because of low risk of radiation effect. The representatives of fusion research is China's EAST, KSTAR of Korea and ITER of world. Korea Superconducting Tokamak Advanced Research(KSTAR) project is on progress for the completion in August, 2007. In this study, the research of utility system for KSTAR be carried out. The utility system of KSTAR is consist of water cooling & heating system, $N_2$ gas system, DI water system, service water system and instrument air & auto control system. The progress of KSTAR utility system is under commissioning state after construction completion. The optimal operation scenario will be verified during commissioning and adopted to the KSTAR operation.

• Computers and Concrete
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• v.32 no.1
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• pp.15-26
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• 2023

In order to study the anti-seismic performance of full light-weight concrete utility tunnel, EL Centro seismic waves were input, and the seismic simulation shaking table test was carried out on the four utility tunnel models. The dynamic characteristics and acceleration response of the system consisting of the utility tunnel structure and the soil, and the interlayer displacement response of the structure were analyzed. The influence law of different construction methods, haunch heights and concrete types on the dynamic response of the utility tunnel structure was studied. And the experimental results were compared with the finite element calculation results. The results indicated that with the increase of seismic wave intensity, the natural frequency of the utility tunnel structure system decreased and the damping ratio increased. The assembling composite construction method could be equivalent to replace the integral cast-in-place construction method. The haunch height of the assembling composite full light-weight concrete utility tunnel was increased from 30 mm to 50 mm to enhance the anti-seismic performance during large earthquakes. The anti-seismic performance of the full light-weight concrete utility tunnel was better than that of the ordinary concrete utility tunnel. The peak acceleration of the structure was reduced by 21.8% and the interlayer displacement was reduced by 45.8% by using full light-weight concrete. The finite element simulation results were in good agreement with the experimental results, which could provide reference for practical engineering design and application.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.131-137
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• 1998

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuated on the variation of insolation, temperature and load. Photovoltaic system needs an inverter which can interface the dc output power of solar cell with the residential ac load. The inverter has to supply a sinusoidal current and voltage to the load and the utility line with a high power factor. This paper proposes an utility interactive photovoltaic system designed with a step-up chopper and a PWM voltage source inverter. The step-up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power points of solar cell without any influence on the variation of insolation and temperature. The voltage source inverter operates in a manner that its output voltage is in phase with the utility voltage. The inverter supplies an ac power with high factor and low level of harmonics to the load and the utility power system.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.278-281
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• 1999

In a utility interactive photovoltaic system, a PWM inverter is used for the connection between the photovoltaic arrays and the utility. The DC current becomes pulsated causes the distortion of the AC current waveform. This paper presents the reduced pulsation of DC input current by operating the inverter with buck-boost chopper in the discontinuous conduction mode. The DC current with contains harmonics component is analyzed by means of separating into two terms of a ripple component and a direct component. The constant DC current without pulsation is supplied from photovoltaic array to the inverter. The proposed inverter system provide a sinusoidal AC current for domestic loads and the utility line with unity power factor.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.719-723
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• 1998

Prevention of the islanding phenomena is one of the most important issues because it can damage electrical equipment connected to the utility system and endanger human life. It is very difficult to detect an islanding condition of a power distribution line with conventional voltage of frequency relays, while the output power and the load power of utility interactive PV inverter units are in nearly balanced state in both active power and reactive power. This paper describes the protective equipment that prevents the PV system connected to the utility grid from starting islanding. Both predictive ocntrol method and harmonic injection method are used for a current control and islanding detection for operating safety.

• Journal of the Korea Society of Computer and Information
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• v.24 no.3
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• pp.57-64
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• 2019

We consider the D2D sum utility maximization in the cellular system. D2D links reuse the uplink resource of cellular system. This reuse may cause severe interference to cellular users. To protect the cellular users, interference limit from the D2D links is required. In this setting, D2D sum utility maximization problem is investigated. Each D2D link has limited transmit power budget. Because optimum solution may require global information between links and computational complexity, we propose the distributed algorithm which only require the local information from each D2D link and simple broadcasting. Simulation results are provided to verify the performance of the proposed algorithm.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.90-95
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• 2015

This paper describes IEC 61727 standard of Photovoltaic (PV) systems -Characteristics of the utility interface. IEC 61727 standard tests include utility compatibility and personnel safety and equipment protection of PV inverter performance functions. Especially utility compatibility part includes test items of 1) voltage, current and frequency, 2) normal voltage operating range, 3) flicker, 4) DC injection, 5) normal frequency operating range, 6) harmonics and 7) waveform distortion, 8) power factor of PV inverter. Also personnel safety and equipment protection part includes test items 1)loss of utility voltage, 2)over/under voltage and frequency, 3)Islanding protection, 4)response to utility recovery, 5)earthing, 6)short circuit protection, 7)Isolation and switching of PV inverter. In this paper, each item of IEC 61727 standard test is studied and analyzed and finally full tested by PV inverter performance function.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.92-99
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• 2021

The ever-growing demand for enhanced competitiveness of engineered systems require designing in quality strategies that can efficiently incorporate multiple design attributes into a system. In a robust design, there must be consideration for any uncontrollable factors that should not be disregarded in the design process. Studies on multi-attribute design challenges usually assume mutual utility independence amongst the design attributes. However, mutual utility independence does not exist in every design situation. In this study, a new robust design methodology that has two utility-dependent attributes are presented. The proposed method was then compared with a traditional robust design that utilizes a wave soldering process design. The results of this case study indicate that the proposed method yields a better solution than the traditional method.