• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.1
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• pp.10-15
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• 1990

This paper presents an algorithm that can compute equivalent impedance effctively in computing 3-phase short circuit current which would be generated in power systems. Also this paper proposes a method that can decide the capacity of circuit breaker by analysing the fault current distribution probabilistically when the fault point of specificed line varies. The efficiency of the algorithm was verified by applying the proposed method to IEEE-6bus system and IEEE-30bus system, and probabilistic fault analysing method is verified economic in facility investment by deciding the proper capacity of circuit breaker.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.5
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• pp.586-592
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• 2018

In this paper, HIC with various functions is proposed for the design 140W LED power control circuit. The proposed HIC integrates constant voltage/constant current circuit, short circuit protection circuit, internal constant voltage circuit, and dimmer circuit, thereby reducing the horizontal length of the PCB by 16% comparing with the conventional system. Through various experiments, we verified the performance of each block implemented inside of HIC with numerical results. (Constant voltage variation ratio: 2.9%, dimmer circuit duty variation within 5%, stable short protection at 720 mA) Since the PCB area can be significantly reduced by applying the proposed HIC. It is possible to reduce the PCB manufacturing time which takes up most of the manufacturing time, however, It is expected that the faulted power module can be replaced without replacing the whole PCB, so that maintenance / repair can be made easier.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.364-367
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• 2009

The role of the low voltage circuit breakers that are installed just before the load is very important for safety. This paper presents a test and analysis of the instantaneous trip characteristics of the Low Voltage 30AF(Ampere Frame) Circuit Breakers, which can be expected to be used for improving the safety of the Low Voltage Circuit Breaker.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.145-150
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• 1996

The variation of spatter generation in gas metal arc welding with welding conditions and wire compositions was investigated and interpreted in terms of arc stability. The transition range from a short circuit mode to a spray mode in the mixed gas welding showed an unstable arc and generated the largest amount of spatters. Titanium reduced spatters only in the globular mode of $CO_2$welding and silicon and manganese showed the same effect The effect of silicon and manganese, however, was no longer seen when titanium was added simultaneously to the wire. It is believed that deoxidizers easily form oxides on the anode and make the arc stable even in DCRP welding. The wires with deoxidizers also showed low short circuit frequency, resulting in the increase of large size spatters.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.106-112
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• 1996

The effects of Ti addition in welding wire on the spatter generation and the droplet transfer phenomena were investigated. With increasing Ti content the spattering rate was decreased but the ratio of large size spatter (D $\geq$ 1. 0mm) was increased in both short circuit and globular transfer mode of $CO_2$welding. In short circuit transfer region, the arcing time was increased and the droplet transfer frequency was decreased with increasing Ti content In globular transfer region, the transition current and voltage to globular transfer was lowered and the welding condition region for stable globular transfer was widened with increasing Ti content.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.9
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• pp.434-440
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• 2005

This paper describes an optimized Scheme of reactive-power compensation for the low short-circuit-ratio AC system interconnected with the HVDC system. An HVDC system interconnected with tile low SCR AC system is vulnerable to the ac voltage variation, which brings about the commutation failure of the converter. This problem can be solved using optimized compensation of reactive power. In this study, a benchmark system for HVDC system interconnected with low SCR AC system is derived using PSS/E simulation. Then an optimized srheme for reactive power compensation was derived using integer programming. The feasibility of proposed scheme was analyzed through silnulations with PSS/E and PSCAD/EMTDC. The proposed scheme can compensate the reactive power accurately and minimize the number of switching for harmonic filters and shunt reactors.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.8
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• pp.401-409
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• 2005

This paper describes a feasibility analysis result of STATCOM application for the Jeju-Haenam HVDC system. The Jeju-Haenam HVDC system is one of the typical HVDC system interconnected with the low short-circuit-ratio AC system, which is vulnerable to the commutation failure due to the AC voltage variation. STATCOM has been considered as an effective reactive-power compensator to increase short-circuit-ratio of the interconnected AC system. In this study, a simulation model of Jeju-Hacnam HVDC system with STATCOM was developed using PSCAD/EMTDC. The developed simulation model was utilized to analyze the dynamic performance analysis of Jeju-Haenam HVDC system with STATCOM. The analysis results show that STATCOM can improve the dynamic performance of Jeju-Haenam HVDC system, such as load-change recovery performance and fault recovery performance.

• 전기의세계
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• v.13 no.3
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• pp.13-20
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• 1964

The measurements of X-ray and Gamma-ray Dose Rate have been successfully made by measuring the short circuit current of the Silicon P-N Junction Diode being irradiated. The short circuit current flows when a silicon P-N Junction Diode is irradiated by X-ray of Gammaray radiations due to photovoltaic effect. A brief analysis is given in order to verify the proportionality of a short circuit current to the Dose Rate. Using this method, measurements of X-ray Dose Rate were carried out in the range of 0.05-1600 r/m successfully. The calibration was made by comparing with Victoreen condenser r-meter. Some advantages in this Dose Rate meter over a condenser r-meter were found. One can measure a continous variation of X-ray Dose Rate with this rate meter at the control console of X-ray device.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.237-239
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• 2006

The residual flux(${\psi}_r$) in transformer's iron cores cause the distortion of short-circuit current occasionally. And some considerable distortion effect on the validation of test results. To prevent this situation, there needs some suitable control of residual flux through the pretest. This paper deals with the how to control the residual flux in pretest and the comparison between the two test results which were obtained by different test method.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.486-491
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• 2001

The effect of S content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80%Ar-$20%CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with S content of wire. Sulfur addition in wire reduced surface tension of droplet and weld pool, and made arc more stable in MAG welding. With increasing S content, the spattering ratio and the ratio of large size spatter ($d{\geq}1.0mm$) were reduced in short circuit transfer mode. In spray transfer mode, spattering ratio, however was increased when sulfur was added more than 0.020wt.% because surface tension of droplets and weld pool was reduced too much even though arc stability was improved.