• Title/Summary/Keyword: Alternative Current (AC)

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Electromigratoin and thermal fatigue in Cu mentallization for ULSI (고집적용 구리배선의 electromigration 및 thermal fatigue 연구)

  • Kim Y.H.;Park Y.B;Monig R.;Volkert C.A.;Joo Y.C
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.1 s.34
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    • pp.53-58
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    • 2005
  • We researched damage formation and failure mechanism under DC(direct current) and AC(alternative current) in order to estimate reliability of Cu interconnects in ULSI. Higher current density and temperature induces more short TTF(time to failure) during interconnects carry DC. Measurement reveals that Cu electromigration has activation energy of 0.96eV and current density exponent value of 4. Thermal fatigue is occurred under DC, and higher frequency and ${\Delta}$T value gives more severe damage during interconnects carry AC Through failure morphology analysis with respect to texture, we observed that damages had grown widely and facetted grains had appeared in (100)grain but damages in (111) had grown thickness direction of line and had induced a failure rapidly.

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Research on Protection Method for Ground Electrode of DC Systems from Corrosion (직류 접지극의 전식보호 방법 연구)

  • Jeong, Woo-Yong;Kim, Hyosung
    • The Transactions of the Korean Institute of Power Electronics
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    • v.26 no.2
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    • pp.90-95
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    • 2021
  • In contrast to AC grounding systems, the ground electrode in DC systems continuously maintains positive or negative polarity. Ground electrodes with (+) polarity proceeds by oxidation reaction. Thus, the DC current should flow opposite to the polarity of the leakage current flowing through the (+) ground electrode by using a compensation electrode, and the current flowing through the (+) ground electrode can be 0A. However, according to protecting the (+) ground electrode, the compensation electrode corrodes and gets damaged. Thus, the (+) ground electrode must be protected from corrosion, and the service life of the compensation electrode must be extended. As an alternative, the average value of the current flowing through the compensation electrode should be equal with the value of the leakage current flowing through the (+) ground electrode by using the square waveform. Throughout the experiment, the degree of corrosion on the compensation electrode is analyzed by the frequency of the compensation electrode for a certain time. In the experiment, the frequencies of the square waveform are considered for 0.1, 1, 10, 20, 50, 100 Hz, and 1 kHz. Through experiments and analysis, the optimal frequency for reducing the electrolytic damage of the (+) electrode and compensation electrode in an LVDC grounding environment is determined.

Acoustic Noise Characteristics Improvement of Solenoid Valve by the Shading Coil Application (쉐이딩 코일의 추가에 의한 솔레노이드 밸브의 소음 특성 개선)

  • Jung, Tae-Uk
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.7
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    • pp.1175-1180
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    • 2008
  • Recently agriculture has been intelligenced and automatized because the number of agricultural population is reduced, and the various agricultural machine is developed and utilized actively, In these agricultural automation system, the solenoid valve is widely used for the supply of water and fertilizer to the plant and soil. In this solenoid valve system, AC excitation solenoid valve is widely used because of economic merit and simple system scheme. However, the instantaneous chattering vibration and noise of plunger caused by the alternative MMF variation is very important performance characteristics. In order to reduce vibration the DC excitation solenoid valve is sometimes applied for the high-end applications. In this case, the control circuit is essential to control DC excitation current. It may causes the cost increase and system complexity and it is not suitable for the outdoor agricultural machine. In this paper, the electromagnetic structural improvement of AC solenoid valve is studied to reduce the dynamic vibration and noise. As an economical solution, the shading coil is additionally implemented to the conventional solenoid valve. As a result of this study, the vibration and acoustic noise is largely reduced by the compensating MMF of shading coil and it is verified by the test of prototype.

Development and Its Properties of Resistance Standards for Using Alternative Current (교류저항 표준기 제작과 그 특성)

  • Kim, Han-Jun;Lee, Sang-Hwa;Kang, Jeon-Hong;Yu, Kwang-Min;Han, Sang-Ok
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.267-268
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    • 2009
  • Resistance standards from 1 ${\Omega}$ to 100 $k{\Omega}$, with calculable frequency dependencies of up to 1 MHz, have been developed for the calibration of commercial inductance-capacitance-resistance (LCR) meters and impedance analyzers. The resistors are designed on the basis of single bifilar loops. The typical resistance change from dc to 1 MHz is from 200 to $800\;{\mu}{\Omega}/{\Omega}$. According to the measurement results, the frequency dependencies of the resistors are severaltimes lower than the measurement uncertainty of commercial LCR meters.

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Research of the cutting force measuring system using feed drive system built in load cell (이송계에 부착시킨 로드셀을 이용한 절삭력 측정시스템에 관한 연구)

  • 강은구;이상조
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.595-598
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    • 2000
  • This paper presents new cutting force measuring system for milling process. Usually, tool dynamometer is the most appropriate measuring tool in an analysis of cutting mechanism. High price and limited space, however, make it difficult to be in-situ system for controllable milling process. Although an alternative using AC current of servomotor has been suggested, it is unsuitable for cutting force control because of low bandwidth and noise. We suggest new cutting force measuring system, using two load cell placed between moving table and nut of ballscrew, and modelled on the system statically and dynamically. And to verify the accuracy of the proposed system, a series of carefully conducted experiments were carried out. Experiment results show that models are in reasonably good agreement with the experiment data.

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High Efficiency DC-DC Converter for Fuel Cell System (연료전지 계통 연계형 고효율 DC-DC 컨버터)

  • Oh, Eun-Tae;Yoon, Soo-Young;Lee, Yoon-Jae;You, Gwang-Min;Chae, Hyung-Jun;Han, Byung-Moon;Lee, Jun-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2410-2415
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    • 2009
  • Studying for environmental friendly and efficient energy source is now actively under way on because problems like environmental pollution and exhaust of natural resources are in issue. Fuel Cell which is an alternative energy source has low voltage and high current characteristic, therefore boost up voltage converter and DC-AC converter is required to use as a common power source. In this paper, DC-DC converter which has high efficient and high power density is proposed and verified by experimental result.

A Highly Efficient AC-PDP Driver Featuring an Energy Recovery Function in Sustaining Mode Operation

  • Kang, Feel-Soon;Park, Sung-Jun;Kim, Cheul-U
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.2B no.3
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    • pp.100-108
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    • 2002
  • A simple sustain driver employing an energy recovery function is proposed as a highly efficient driver of a plasma display panel. The proposed driver uses dual resonance in the sustaining mode operation: a main resonance between an inductor and an external capacitor to produce alternative pulses and a sub-resonance between an inductor and a panel to recover the energy consumption by the capacitive displacement current of the PDP. The operational principle and design procedure of the proposed circuit are presented with theoretical analysis. The operation of the proposed sustain driver is verified through simulation and experiments based on a 7.5-inch-diagonal panel with a 200 KHz operating frequency.

Corrosion Monitoring of Reinforcing Bars in Cement Mortar Exposed to Seawater Immersion-and-dry Cycles (해수침지-건조 환경에 노출된 모르타르속 철근의 부식속도 평가)

  • Kim, Je-kyoung;Kee, Seong-Hoon;Yee, Jurng-Jae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.10-18
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    • 2018
  • The primary purposes of this study are to understand a fundamental aspect of current uniformity around a reinforcing bar (rebar) in cement mortar, and to develop an accurate monitoring method in a wet-dry cycling process with the alternative current (AC) impedance method. Three cement mortar specimens with two embedded rebars were prepared in the laboratory. As a main variable, the distance between two rebars was designed to be 10, 20 and 30 mm with the same thickness of 20 mm. To simulate the corrosion of rebars in concrete structures in a marine environment, three cement mortar specimens were exposed to 15 wet-drying cycles (24-hour-immersion in seawater and 48-hour-drying in a room temperature) in the laboratory. It was observed that the potential level shifted to a noble value during corrosion potential monitoring, which is attributed to acceleration of dissolved oxygen diffusion at the drying process. AC impedance was measured in a frequency range from 100 kHz to 1 mHz on a wet-drying process. A theoretical model was proposed to explain the interface condition between the rebars and cement mortar by using the equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE (constant phase element). It was observed that the diffusion impedance appeared in a low frequency range as corrosion of rebars progresses. At the drying stage of the wet-drying cycles, the currents line for monitoring tended to be non-uniform at the interface of rebar/mortar, being phase shift, ${\theta}$, close to $-45^{\circ}$.

Economic Analysis of a Residential Ground-Source Heat Pump System (단독주택용 지열원 열펌프 시스템의 경제성 분석)

  • Sohn, Byong-Hu;Kang, Shin-Hyung;Lim, Hyo-Jae
    • New & Renewable Energy
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    • v.3 no.4
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    • pp.31-37
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    • 2007
  • Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these advantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conventional HV AC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total pollutant emissions than the alternative HVAC systems considered in this work.

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Improvement of LCC-HVDC Input-Output Characteristics using a VSC-MMC Structure

  • Kim, Soo-Yeon;Park, Seong-Mi;Park, Sung-Jun;Kim, Chun-Sung
    • Journal of the Korean Society of Industry Convergence
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    • v.24 no.4_1
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    • pp.377-385
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    • 2021
  • High voltage direct current(HVDC) systems has been an alternative method of a power transmission to replace high voltage alternate current(HVAC), which is a traditional AC transmission method. Due to technical limitations, Line commutate converter HVDC(LCC-HVDC) was mainly used. However, result from many structural problems of LCC-HVDC, the voltage source converter HVDC(VSC-HVDC) are studied and applied recently. In this paper, after analyzing the reactive power and output voltage ripple, which are the main problems of LCC-HVDC, the characteristics of each HVDC are summarized. Based on this result, a new LCC-HVDC structure is proposed by combining LCC-HVDC with the MMC structure, which is a representative VSC-HVDC topology. The proposed structure generates lower reactive power than the conventional method, and greatly reduces the 12th harmonic, a major component of output voltage ripple. In addition, it can be easily applied to the already installed LCC-HVDC. When the proposed method is applied, the control of the reactive power compensator becomes unnecessary, and there is an advantage that the cut-off frequency of the output DC filter can be designed smaller. The validity of the proposed LCC-HVDC is verified through simulation and experiments.