• Analytical Science and Technology
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• v.7 no.3
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• pp.361-369
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• 1994

Voltammetric behavior of some light lanthanide ions($La^{3+}$, $Pr^{3+}$, $Nd^{3+}$, $Sm^{3+}$ and $Eu^{3+}$) in acetonitrile(AN) and dimethylformamide(DMF) has been investigated by direct current, differential pulse polarography and cyclic voltammetry. The reduction of $La^{3+}$, $Pr^{3+}$ and $Nd^{3+}$ in 0.1M TEAP proceeded directly to the metallic state through three-electron charge transfer of irreversible process where as $Sm^{3+}$ and $Eu^{3+}$ proceeded by charge transfer of two steps. As the results of the cyclic voltammetric investigation, the first step reduction of $Sm^{3+}$ and $Eu^{3+}$ were a quasireversible reaction, the second step reductions were an irreversible reaction. The cathodic peak currents of the differential pulse polarogram showed adsorptive properties at lower sweep rates and high concentrations of these metal ions. The peak potenital was shifted to a negative petential and the peak current decreased with the increase of percentage of water in AN. On the other hand, the peak potential was shifted to a positive potential and the peak current decreased with an increased percentage of water in DMF.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.469-475
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• 2003

Resistive leakage current flowing ZnO blocks increases with its ages, which is an important indicator of arrester deterioration. However, a complicated circuitry is essential to measure the resistive leakage current included in the total leakage current, and the difficult handling of the measurement makes few applications to the fields. In this paper, we propose a resistive leakage current measurement device which is composed of a current detection circuit and an analysis program operated on a microprocessor. The device samples the input leakage current waveform digitally, and discriminate the zero-cross and the peak point of the waveform to analyze the current amplitude vs. phase. The capacitive leakage current is then eliminated from the total leakage current by using an algorithm to extract the resistive leakage current only. Also, the device can be operated automatically and manually to analyze the resistive leakage current even when the leakage current waveform is distorted due to various types of arrester deterioration. To estimate the performance of the device, we carried out a test on ZnO blocks and lightning arresters. From the results, it is confirmed that the device could analyze most parameters needed for the arrester diagnostics such as total leakage current. resistive leakage current, and the $3^rd$ harmonic leakage current.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.550-555
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• 1994

The effects of RTA treatment on the leakage current have been studied for tantalum pentoxide( $Ta_2O_5$) films deposited by PECVD on P-type(100) Si substrate using $TaCl_5$(99.99%) and $N_2O$(99.99%) gaseous mixture. The refractive index increased with increasing the deposition temperature and the maximum deposition rate was obtained at $500^{\circ}C$. The Ta-0 bond peak intensity of as-deposited $Ta_2O_5$ increased with increasing the deposition temperature through FT-IR analysis and the leakage current value was decreased with increasing the deposition temperature. The small leakage current value obtained after RTA treatment of as-deposited $Ta_2O_5$ was found to be due to the reduction of 0-deficient structure in the film. The increases of the oxygen coacentration and the Ta-0 bond peak intensity in the film after RTA treatment were measured by AES and FT-IR analyses.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.905-914
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• 2016

This paper proposes a new phase current reconstruction technique for interleaved three-phase bidirectional dc-dc converters using a single current sensor. In the proposed current reconstruction algorithm, a single current sensor is employed at the dc-link, and the dc-link current information is sampled at either the peak or valley point of the pulse-width modulation (PWM) carriers regularly. From the obtained current information, all phase currents are reconstructed in a single PWM cycle. After that, the digital current controller is applied to achieve current balancing in each phase. Compare to the previous multiple current sensor method, the proposed strategy reduces the number of the current sensors in the interleaved three-phase bidirectional converter as well as reducing potential current sensing error caused by non-ideal characteristics of the multiple current sensors. The effectiveness of the proposed method is verified from the experiments based on a 3kW three-phase bidirectional converter prototype for the automotive battery charging application.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1996.11a
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• pp.101-103
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• 1996

This Paper describes Peak load forecasting technique of pole transformers with correlation equation. While customers are demanding safe energy supply, current correlation equation that is used for load management of pole transformers has some problems. To get accurate correlation equation. several correlation equation were examined using past data and nu data collected using the measuring instrument developed for this study. It was recognized that the quadratic equation was the most accurate for peak load forecasting from working electrical energy.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.299-303
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• 1993

Erbium metal을 불순물로서 2mol% 첨가한 TlGaS2:Er3+ 단결정을 수평전기로에서 합성한 ingot를 사용하여 수직 Bridgman 방법으로 성장시켰다. 성장된 결정은 층상으로 이루어진 monoclinic 구조였으며, 10K에서 간접전이형 및 직접전이형 energy band gap은 각각 2.55eV, 2.57eV이었고, Er3+ 이온에 의한 두 개의 불순물 광흡수 peak가 524.9nm와 656.4nm에서 관측되었다. Themally stimulated current(TSC)를 측정하여 0.21eV와 0.38eV의 donor 준위와 0.71eV의 accptor 준위를 구하였다. 10K에서 측정된 photoluminescence(PL) spectrum에서는 632nm와 759nm에서 D-A pair에 의한 broad한 peak와 552, 559, 666, 813, 816, 827nm에서 Er3+ 이온에 의한 sharp한 peak들이 나타났다.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1045-1047
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• 1992

Photovoltaics is considered to be one of the most promising technologies which can greatly contribute to future energy supply because of a large, secure, essentially inexhaustible and broadly available resource - sunlight. However, recent progresses in photovoltaics make also possible its short-term practical application in some areas. Among them the solar air conditionner powered by photovoltaic system attracts considerable interest due to its main advantage which consists in the reduction of drastically increasing electricity peak load in summer season. In this review paper our current study on the solar air conditionner will be briefly summarized.

• Current Photovoltaic Research
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• v.5 no.2
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• pp.43-46
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• 2017

Large absorption band shift has been observed for the azo-dye (disperse red-13, DR-13) attached on the surface of silica spheres. Urethane linkage has been utilized to form covalent bond between azo-dye (-OH) and 3-isocyanatopropyltriethoxysilane (ICPTES, -N=C=O). The synthesized ICPTES-DR-13 (ICPDR) molecules were attached to the silica spheres by the hydrolysis and condensation reaction. Although the absorption peak of DR-13 in methanol is at 510 nm, the absorption peak of the ICPDR-silica spheres shifts to 788 nm. The large absorption peak shift is due to the formation of intramolecular charge-transfer band with large aggregated ICPDR.

• 전자공학회논문지 IE
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• v.49 no.2
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• pp.40-45
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• 2012

In this paper, cooling system of power transformers is proposed for temperature optimized control. We predict the peak temperature of power transformer coils using load factors and construct a cooling system using weighting function. For the optimized temperature control for power transformer, a correlation function based on the load factor of a load current and the each temperatures for winding coils, for air and for oil is presented to predict the winding-coil peak temperature. Also, the results controlled by applying the power transformer is presented.

• Journal of Magnetics
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• v.6 no.1
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• pp.36-41
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• 2001

A micromagnetic model and a single-domain model simulation programs were used to analyze the sensitivity of a $20\mu m\times 60\mu m \times 1000{\AA}$ permalloy strip as a magnetoresistance sensor with bias fields of various directions and magnitudes. The micromagnetic model agrees with the measured sensitivity data better than the single-domain model. The data show the highest peak sensitivity with the bias field at 90$^{\circ}$to the current. The peak sensitivity decreases and the peak broadens as the bias angle decreases. The simulation using the micromagnetic model shows that a bias angle smaller than 90$^{\circ}$eads to magnetization patterns which are free from closure domains or vertices over a wider range of bias fields.