• Current Photovoltaic Research
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• v.11 no.4
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• pp.118-123
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• 2023

The main cause of solar facility fires is arc, and in the last 3 years ('16 to '18), about 80% of domestic solar facility fires have been caused by arcs. The capacity of solar power facilities installed around the world continues to increase, and fires caused by arcs are also expected to increase as the solar power generation facilities that were initially installed become obsolete, In this paper, an arc generation test was conducted based on the UL1699B test standard. As a result of the test, the arc generation satisfied the minimum arc current according to the test conditions, and DC arc characteristics were analyzed through data such as arc voltage and arc current according to variables such as speed of moving electrodes and electrode spacing.

• Asia pacific journal of information systems
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• v.31 no.3
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• pp.433-447
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• 2021

The purpose of this paper is to shed light on the current status of Industry 4.0 policies in India and provide holistic policy recommendations in the transition towards Industry 4.0. The study was conducted based on the content-centric review of written policy documents like policy memoranda (memos), green papers and white papers, policy briefs, policy reports, opinion pieces, and newspaper and academic publications on Industry 4.0. India lacks infrastructure, regulatory framework, architectural reference model, incentives, skills, and standard roadmap towards Industry 4.0. The current policy status and policy recommendations presented in this study can serve as a great asset for academicians, policymakers, and practitioners to prepare a holistic roadmap for Industry 4.0 policy implementation. The study is first to assess India's current policy status and compare with Germany towards Industry 4.0. Besides, it is expected to assist government policymakers in formulating tangible policy outputs and strategic roadmaps.

• Korean Journal of Radiology
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• v.22 no.11
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• pp.1749-1763
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• 2021

Coronary computed tomography angiography (CCTA) is routinely used for anatomical assessment of coronary artery disease (CAD). However, invasive measurement of fractional flow reserve (FFR) is the current gold standard for the diagnosis of hemodynamically significant CAD. CT-derived FFRCT and CT perfusion are two emerging techniques that can provide a functional assessment of CAD for risk stratification and clinical decision making. Several clinical studies have shown that the diagnostic performance of concomitant CCTA and functional CT assessment for detecting hemodynamically significant CAD is at least non-inferior to that of other routinely used imaging modalities. This article aims to review the current clinical evidence and recent developments in functional CT techniques.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.11a
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• pp.57-74
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• 1997

To make a proposal for the revision of KGCP, ICH Harmonized Tripartite Guideline for Good Clinical Practice, which is on the stage of worldwide implementation, was compared with current GCPs of tripartite countries of ICH, namely USA, Europe and Japan as well as Korea. On the basis of the classification in ICH GCP, comprehensive comparisons among the corresponding articles of 4 regions or countries were made in the order of IRB / IEC, Investigator, Sponsor and Clinical Trial Protocol. Based on the comparisons of the contents in ICH-GCP with those in current GCPs, major suggestions for the revision of current KGCP can be made as follows. Firstly, the function of IRB / IEC needs to be strengthened for the initiation and continuation of clinical trial. Current 2-step approval system of IRB / IEC and Health Authorities requires to be converted into the system similar to that of developed countries. Secondly, sponsor's obligation needs to be tightened to control and assure the quality of clinical trial. Inspection of regulatory authorities should be made to perform during and / or after clinical trial, when it is necessary. In other words, sponsor should be made to establish written Standard Operating Procedures (SOPs) for all aspects of clinical trial including monitoring to ensure that trials are conducted and data are generated, documented, and reported in compliance with the protocol, GCP, and the applicable regulatory requirement (s). Besides, the provision of ‘Quality Control and Quality Assurance’ should be added to the protocol to establish the credibility of the result of the clinical trial.

• Journal of Welding and Joining
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• v.8 no.1
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• pp.31-42
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• 1990

Arc must be stable during welding first of all other factors for obtaining sound weldment, especially in the automation of welding process. Arc stability is somewhat sophisticated phenomenon which is not clearly defined yet. In consumable electrode welding, the voltage and current variation due to metal transfer enables to assess arc stability. Recently, statistical analyses of the voltage and current waveform factors are performed to assess the degress of arc stability which is assessed and controlled by operator's own experience by now. But, considering the increasing need and the trend of automation of welding process, it is necessary to monitor arc stability in real-time. In this sutdy, the modified stability index composed of two voltage and current wvaeform factors (arc time and short circuit time) reduced from four factors (arc time, short circuit time, average arc current and average short circuit current) in Mita's index by the welding electrical circuit modeling is proposed and verified by experiments to be well estimating arc stability in the static sense. Also, the recursive calculation form estimating present arc stability in the dynamic sense is developed for real-time estimation. The results of applying the recursive index during welding show good estimation of arc stability in real-time. Therefore, the results of this study offers the mean for real-time control arc stability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1651-1655
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• 2011

The reference impedances which is about 95% supply impedance value of residential consumers' supply impedances was published by IEC in 1980. The reference impedances are the standard values for use in determining the voltage disturbance characteristics of electrical equipment like the flicker. In IEC 60725, the reference impedances for premises having service current capacities less than 100A per phase and for service current capacities more than 100A per phase are recommended. And these reference impedances are targeted for the countries using 50Hz power frequency. Because of the frequency difference, the reactance values of the reference impedances will be increased in 60Hz power system like Korea, And also the reference impedances are different significantly each other according to declared voltage variation, power consumption and service wire length etc. Therefore It is needed to calculate the reference impedances suitable for domestic low-voltage power system. In this paper, the reference impedances for service current capacities less than 100A in 220/380V, 60Hz single-phase two wire and three-phase four wire low-voltage system are calculated, And the equations for service current capacities more than 100A to calculate the modulus value of maximum supply impedances are suggested base on IEC 60725 and the reference impedances for those are calculated on service current of 100A per phase.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.371-373
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• 2005

An enhancement for a transmission and substation equipment in power system make the system impedance to be lower. In principle, if the system impedance become low, system stability will be better, but the fault current become very higher. It is a very big problem for CB operating. As a fact of CB operating performance, high amplitude of the fault current may cause CB operation failure because of exceeding standard value in TRV. So we simulated TRV by using the EMTP. Generally there are two types of TRV in actual power system. One is short line fault, the other is bus terminal fault. In this paper, we simulated the TRv at short line fault as installed current limit reactors to reduce fault current in 345kV ultra-high voltage system. Short line fault is caused from single line fault in transmission line.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.99-106
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• 2012

For CMOS technology of 65 nm and beyond, the gate leakage current can not be negligible anymore. In this paper, the impact of the gate leakage current in ring voltage-controlled oscillator (VCO) on phase-locked loop (PLL) is analyzed and modeled. A voltage -to-voltage (V-to-V) circuit is proposed to reduce the voltage ripple on $V_{ctrl}$ induced by the gate leakage current. The side effects induced by the V-to-V circuit are described and optimized either. The PLL design is based on a standard 65 nm CMOS technology with a 1.8 V power supply. Simulation results show that 97 % ripple voltage is smoothed at 216 MHz output frequency. The RMS and peak-to-peak jitter are 3 ps and 14.8 ps, respectively.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.60-68
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• 2000

This paper describes a design methodology for the CMOS current source which can be implemented in standard memory process. The proposed techniques provide a good characteristic against the power-supply variation by utilizing a self-bias circuit and the reduction of the first-order component of the temperature variation through the new temperature compensation technique and include a new current-sensing start-up circuit enabling a robust operation against the voltage noise generated during the operation of the chip. In addition to the circuit-design technology, techniques where the proposed CMOS current-reference circuit can be applied to the clocking circuits of a very high-speed DRAM are presented. The feasibility of the suggested design methodology for the CMOS current reference is demonstrated by both the analytical method and the circuit simulation.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.225-231
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• 2009

The purpose of the current study was to compare radiation dose of 64MDCT performed with automatic exposure control (AEC) with manual selection fixed tube current. We evaluated the CT scans of phantom of the chest and abdomen using the fixed tube current and AEC technique. Objective image noise shown as the standard deviation of CT value in Hounsfield units was measured on the obtained images. Compared with fixed tube current, AEC resulted in reduction of the chest and abdomen in the CTDIvol (35.2%, 5.9%) and DLP (49.3%, 3.2%). Compared with manually selected fixed tube current, AEC resulted in reduced radiation dose at MDCT study of chest and abdomen.