• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.2
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• pp.32-38
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• 2013

In recent years, anti-PID (Potential Induced Degradation) technologies have been studied and developed at various stages throughout the solar value chain from solar cells to systems in an effort to enhance long-term reliability of the photovoltaics (PV) system. Such technologies and applications must bring in profits economically for both manufacturers of solar cell/module and investors of PV systems, simultaneously for the development of the PV industry. In this study two selected anti-PID technologies, ES (modification of emitter structure) and ARC (modification of anti-reflective coating) were compared based on the economic features of both a cell maker with 60MW production capacity and an investor of 1MW PV power plant. As a result of this study, it is shown that ARC anti-PID technology can ensure more profits over ES technology for both the cell manufacturer and the investor of PV power plant.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.6
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• pp.452-458
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• 2019

This study proposes a new test circuit and control method for the submodules of modular multilevel converter (MMC)-based HVDC systems. The test current of conventional submodule test circuits cannot provide the DC offset components or may have some distortion in the linearized current with the DC offset. The proposed scheme can provide not only the DC component but also linearized current without distortion. Therefore, the submodule test current waveform is relatively similar to that of a real submodule consisting of an MMC-based HVDC system. The validity of the proposed circuit and control method is verified through a simulation and experiment.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.333-334
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• 2016

This paper proposes a new cascoded configuration for hybrid energy storage system (HESS) which consists of batteries and supercapacitor (SC) for Electric Vehicle applications. In this configuration,a resonant LLC converter is interfacedin series with a battery module and it converts a part of the energy from the batteries and transfer it to the dc-link bus. The LLC converter is controlled by a phase-shift angle between the primary and secondary switches to maintain a constant dc-link voltage and obtain soft-switching conditions for all the primary switches. By placing the SC moduleina cascoded concept, the rated voltage of SC can be reduced significantly compared with the conventional topologies. It helps save the cost and reduce the number of SC cells. The proposed configuration can operate with four different modes: feeding load, acceleration, regenerative braking andSC charging. A scaled-down prototype converter (2 kW, 600V output) is designed and tested to verify the advantages of the proposed topology. The maximum efficiency obtained with the proposed topology is 99%.

• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.62-66
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• 2015

This paper introduces various applications and contents of digital signage, and analyzes conventional communication techniques to increase communication range. To realize digital signage in long distance, this paper proposes a hybrid modulation scheme and analyzes its performance. To verify its performance in real channel environment, we mapped symbols and experimented data transmission and reception with a visible light communication module with USRP. As a result, we confirmed a data receiving range and power of transmission and reception of the hybrid modulation mode. Also, we showed that the proposed modulation scheme has better performance of communication range and power efficiency than that of the conventional QAM technique.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.57-61
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• 2015

A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.120-125
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• 2012

Daegu Solar Power Tower Plant of a 200 kW thermal capacity uses an open air receiver. An air receiver is generally based on the volumetric receiver concept with porous ceramic absorbers. Because absorber material is important in the volumetric receiver, ceramic materials with excellent thermal conductivity, high solar absorptivity and good thermal stability have been researched. KIER also developed SiC honeycomb absorber modules and evaluated performance of the modules at the KIER solar furnace. For performance evaluation, we made an open volumetric receiver containing the modules and measured the outlet temperature and the efficiency. It is demonstrated that performance of the KIER absorber is comparable to that of a reference absorber developed by DLR.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.38-45
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• 2013

In this study, for carrying out the spray and combustion experiment using a Common Rail Direct Injection(CRDI) system, the controller was fabricated to drive a high speed camera, a injector and a laser beam sequentially at a low cost. CB280 module of one-chip micro processer was used for the controller. In order to confirm responsibility and utility of the controller, the current drive performance, the spray behavior and the injection rate were tested and analyzed under various experimental conditions. As this research results, we found that the fabricated controller was able to control the devices for the spray experiment precisely with the input value in program and it had the dynamic load responsibility and repetition. Also, we found that the injection rates of our experimental results were higher than those of others at the same injection pressure and the controller connected with the laser system and the data acquisition system had validity for carrying out the spray visualization experiment.

• Journal of IKEEE
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• v.15 no.4
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• pp.261-266
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• 2011

In this paper, new efficient lighting control system for light devices is proposed to reduce power consumption and increases LED life-cycle and heat efficiency of LED lighting module. The new proposed lighting control system for light devices divides into 4 stages according to the illuminance surrounding by measuring illuminance and apply to automatic pattern lighting algorithm. And via level check will be light up for set time by applying intersection lighting algorithm of magic square pattern forming a fully symmetrical. Experimental analysis results, shows heating value and power consumption reduced to maximum 30 percent and lifetime of LED improved to maximum 60 percent in comparison with previous lighting system so applying system to LED streetlight, stable and high energy efficiency can be acquired.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.1
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• pp.15-21
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• 2005

One of the core technology in WDM-PON system is a generation and modulation technique of the optical source in Optical Network Unit (ONU). In this paper, we propose a reflective semiconductor optical amplifier (RSOA) as a modulator in WDM-PON system. Its performance is analyzed by simulation and actual experimentation. Using RSOA in WDM-PON system as a modulator, it obtains higher gain compared to the conventional SOA due to the double pass gain effect. Furthermore RSOA can provide high gain with comparatively low input power. This is very helpful when we set up the actually system because using lower input power, it can reduce the load of the driving circuit which makes very economical module structure. Therefore, when RSOA is used as a modulator, not only it gives noise suppression effect, but also provides certain amount of gain as well. In addition, comparing with conventional SOA which gives fairly large insertion loss, RSOA can provides more important merits.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1816-1822
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• 2003

We propose a novel structure of wavelength selective optical add/drop filter comprising two tap couplers and a fiber Bragg grating. The device has unique features including a simpler structure and a lower cost implementation as compared with existing device for the same operation. The filter performance has been measured and analyzed, experimentally. The implemented prototype filter shows good performance with no­crosstalk power penalty in a 155Mbps per channel wavelength­division­multiplexing transmission system but suffers from a relatively high loss of 3.5㏈ and 21㏈ for transmitted and dropped channel, respectively. While the dropped channel extinction ratio was more than 15㏈, the transmitted channel extinction ratio was more than 26㏈.