• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.247-251
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• 2006

The traction DC feeder cable is one of the key devices for the safety operation of subway system, but for low voltage DC feeder cable (<3000 V) for subway, little attention has been paid by investigators on its online monitoring technology. With an introduction of cable laying and operation environment for the cable, this paper investigated the on-line monitoring technology of 1500 V DC feeder cable of subway. Firstly, in the text, the fault model of 1500 V DC cable was proposed based on the analysis of the fault type of the DC feeder cable, and then put forward synthetically on-line monitoring discharge signal and DC leakage current signal to assess DC feeder cable insulating state. The results of laboratory experiment prove that the proposed methods are feasible and can be implemented on-line monitor on DC feeder cable of subway.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.428-435
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• 2005

In this paper a power controller is proposed to accurately control the commanded power for charge and discharge operation of a bidirectional DC-DC converter so that durability is improved in hybrid systems such as fuel cell vehicles. Also, a control algorithm for charge and discharge operation is proposed to improve fuel utilization and keep battery SOC constant so that energy is effectively utilized.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1159-1159
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• 2015

This paper conducted the basic study on partial discharge analysis under the DC voltage. For the purpose, typical discharges such as void discharges, corona discharges and surface discharges with DC voltage were generated and measured. As a pattern analysis, various methods were adopted using the information including PD magnitudes and time interval.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.721-726
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• 1995

In this paper, reduction characteristics of NOx gas produced from diesel engine combustion is studied by using pulse corona discharge. Nox concentration of 1900ppm (NO 1870, NO$\sub$2/ 30 ppm, N$\sub$2/ balance gas) was controlled in a fixed quantity of 280ppm, using a flow meter. Reactors are composed of cylinder type. NOx reduction rate is investigated with discharge electrode diameter[0.5,1,3,4.phi.], reactor length [130,300mm], reactor materials[Copper, Poly Vinyl Chloride] and Input voltage[DC, AC, DC Pulse square voltage]. In the result, NOx reduction rate is the best of all in copper reactor, small electrode diameter[0.5.phi.], DC pulse voltage and long reactor[300mm]. Then Teduction rate of NOx is about 93%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.13-18
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• 2014

On 250.199nm uv-line, witch has the potential to emit as a laser line, from a ccrf-excited He-Zn discharge with overlapped DC was carried out optimization of the discharge parameters and measurement of the optical gain. In this study the optical gain of the 250.199nm uv-line has been optained 4% for the first time. At a rf-power of 400W with the frequency 13.56MHz the optimal He-pressure indicated 2kPa.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.205-206
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• 2010

This paper presents a study on the efficiency of DC-DC converter to charge/discharge lithium battery. The losses of switching device, magnetic components, output capacitor, diode, and snubber circuit are analyzed by considering the charge/discharge characteristics of the converter. Based on the loss analyses, efficiency simulation in charging/discharging process are performed.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.383-387
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• 2007

In this paper the design of the discharge cleaning system for KSTAR vacuum vessel is described. We first discuss about the parameters which are related the efficiency of discharge cleaning. The RG(RF-assisted Glow) discharge which has the ignition and sustain pressure lower than those in the case of DC discharge, thus has the higher efficiency of discharge cleaning. So we adopt the RG discharge, in practical design, for KSTAR discharge cleaning system. For uniformity of the cleaning effect, we plan to install two discharge cleaning systems in A- and I-port of the KSTAR vacuum vessel. The designed system will be adapted for the study of the fuel recycling and of the boronization as well as the discharge cleaning of the KSTAR vacuum vessel.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.61-68
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• 2014

Function of battery bank stores energy for DC load in general, and DC power system of the nuclear power plant is used to supply DC loads for safety- featured instrumentation and control such as inverter, class 1E power system control and indication, and station annunciation. Class 1E DC power system must provide a power for the design basis accident conditions, and adequate capacity must be available during loss of AC power and subsequent safe shutdown of the plant. In present, batteries of Class 1E DC power system of the nuclear power plant uses lead-acid batteries. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration and discharge end voltage, etc. This paper summarizes standards of determining battery size for the nuclear power plant, and analyzes duty cycle for the class 1E DC power system of nuclear power plant. Then, battery cell size is calculated as 2613Ah according to the standard. In addition, this paper analyzes performance test results during past 13 years and shows performance degradation in the battery bank. Performance tests in 2001 and 2005 represent that entire battery cells do not reach the discharge-end voltage. Howeyer, the discharge-end voltage is reached in 14.7% of channel A (17 EA), 13.8% of channel B (16 EA), 5.2% of channel C (6 EA) and 16.4% of channel D (19 EA) at 2011 performance test. Based on the performance test results analysis and size calculation, battery capacity and degradation by age in Korearn nuclear power plant is discussed and would be used for new design.

• Korean Journal of Materials Research
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• v.5 no.2
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• pp.178-183
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• 1995

Piezoelectric properties of sintered specimen having a tetragonal phase of $Pb_{0.9888}Sr_{0.012}(Zr_{0.52}Ti_{0.48})O_{3}$ were comparatively studied with two different poling methodes, i.e., DC field and corona discharge technique. Internal stress of poled specimens by indentation fracture toughness was analyzed to evaluate degradation phenomenon. As the results, it was confirmed that corona discharge poling technique is practicable and has merits such as low-temperature poling, slow degradation and no electric breakdown comparing to DC field poling. However, corona discharge technique showed lower Kp value than DC field poling.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.441-450
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• 2010

Lithium battery is widely used as the power source of various electronic devices. The formation process which is the repeated charging and discharging process is essential in the production of lithium battery. In this paper, it is proposed and designed the DC-DC converter that can charge and also discharge the lithium battery in one converter. The proposed converter is designed by considering the charge/discharge characteristics of the lithium battery. The converter is operated as a forward converter in charging process and a electrically isolated boost converter in discharging process. Based on the analyses, the number of transformer turns, inductor, capacitor, and switching devices are designed. Finally, the validity of the design for the proposed converter is verified by both simulations and experiments.