• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.976-978
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• 2003

Quench characteristics of HTS tapes, which are applied over-current were investigated. When the applied current exceeds the critical current of HTS tapes, the superconductor of HTS tape comes to be changed into normal conductor so that the current begins to flow through the metal sheath, which is made of good electrical conductor. In this study, the current, corresponds to 10 times $I_c$ was fed to HTS tapes. Using the V-I curves and resistance with temperature variation of HTS tapes, the distribution of the applied current between superconductor and metal sheath was analyzed. As the results, we could acquire the duration and magnitude of current to reach to thermal quench.

• JOURNAL OF ELECTRICAL WORLD
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• no.10 s.106
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• pp.28-33
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• 1985

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.1
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• pp.111-116
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• 2015

In this study, the constant current converter for LED lighting was designed and the electrical characteristics of the fabricated SMPS was measured. When the output current is 300mA the maximum efficiency of 85% was shown and the output current is in the range of 100~400mA efficiency over 70% were exhibited. Also the dimming levels control over the range of 0 to 100% was possible by using a control signal of 0~250mV.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1617-1621
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• 2011

In this paper, in order to reduce the electrical disaster such as electrical fire at traditional markets, we need to develop the circuit breaker which is able to monitor the power status of electrical equipments. Therefore, for solving the those problems, we developed the detection censor(ZCT, CT) and equipment of data analysis and transmission. The detection censor and equipment is able to monitor the electrical equipments condition(over current, leakage current, arc, etc.). We constructed Test-Bed for testing reliability of the circuit breaker and obtained certification. And we tested the over current, leakage current and arc under the normal condition. This paper will be used to the data for development an cabinet panel which is able to monitor the actual loads.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1367-1374
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• 2016

This paper presents a discrete-time version of voltage and current limited operation using an enhanced direct torque and flux control method for interior permanent magnet synchronous motor (IPMSM) drives. A command voltage vector for airgap torque and stator flux regulation can be uniquely determined by the finite-settling-step direct torque and flux control (FSS-DTFC) algorithm under physical constraints. The proposed command voltage vector trajectories can be developed to achieve the maximum inverter voltage utilization for the discrete-time current limit (DTCL)-based FSS-DTFC. The algorithm can produce adequate results over a number of the potential secondary upsets found in the steady-state current limit (SSCL)-based DTFC. The fast changes in the torque and stator flux linkage improve the dynamic responses significantly over a wide constant-power operating region. The control strategy was evaluated on a 900W IPMSM in both simulations and experiments.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.43-47
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• 1980

The author designed and tested the high sensitive three-phase power factor meter and relay circuit, and dealt with the circuit to detect the phase of the current and the voltage. An operational amplifier comparator circuit and two single-phase transformers are used to control and detect the phase angle between the current and the voltage. The results obtained are as follows: 1. Converting the sine wave input current into the constant amplitude rectangular wave form by using a transistor chopper circuit, the power factor can be measured precisely over the load current of 0.08 A. 2. Using the moving coil type current meter, the power factor meter can be read in uniform . scale all over the range. 3. Using the three-phase power factor meter, the power factor relay which works at any power factor can be made.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.335-339
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• 2010

In this paper, in order to reduce the electrical disaster damage which is caused by with electrical equipment of traditional markets, we developed the cabinet panel and the electrical safety monitoring system which is able to monitor the electrical equipments condition(over current, leakage current, arc, WH, electrical fire factor etc.) at traditional markets. We constructed Test-bed for testing reliability of electrical safety monitoring system and cabinet panel. And we tested the cabinet for over current, leakage current and arc under the traditional markets actual condition. This paper will be used with the data for an demonstration project after compensating the defects which are occurred to operation of traditional markets actual loads.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.5
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• pp.424-428
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• 2003

The channel of a superconducting flux flow transistor has been fabricated with plasma etching method using a inductively coupled plasma etching. The ICP conditions then were ICP Power of 450 W, rf chuck power of 150 W, the pressure in chamber of 5 mTorr, and Ar : Cl$_2$=1:1. Especially, over the 5 mTorr, the superconducting thin films were not etched. The channel etched by plasma gas showed the critical temperature over 85 K. The critical current of the SFFT was altered by varying the external applied current. As the external applied current increased from 0 to 12 mA, the critical current decreased from 28 to 22 mA. Then the obtained trans-resistance value was smaller than 0.1 $\Omega$ at a bias current of 40 mA.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.713-717
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• 2004

This is a thesis that a quarter-brick size of 100W class open-frame type on board power module comprising telecommunication application is reported. The input voltage is established between 36 and 75 in range in order for power module to be utilized for the telecommunication application, and output were set at 3.3V and 30A. A number of parts used for transformer, inductor, and hit sink are composed of PCB in order for DC-DC converter to be lowered below 8 mm. A constant current control circuit was annexed to the system as well as basic protection prototypes such as over-voltage, over-current, and over-temperature were well considered to enhance more credibility, and were tested. As a result, high circuit performance and credibility turned out to be significant.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1846-1849
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• 1998

An optical magnetic filed sensor, YIG (Yittrium Iron Garnet), response rapidly, to the power-line currents to be measured. In response to Faraday effect, it shows wide-and-linear measurable range. This paper reports the development and implementation of an OOCR (Optoelectric OverCurrent Relay) using this sensor. This relay is free from environmental electro-magnetic noises and has excellent insulation characteristics inherently. By using this OOCR, we can reduce insulation cost of protective relaying systems and its maintenance cost, and can achieve high reliability of the system.