• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.110-116
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• 2004

We propose a novel sensing scheme, which operates by sensing the difference in voltage between a memory cell and a reference cell for a magneto-resistive random access memory (MRAM). A new midpoint-reference generation circuit is adopted for the reference cell to improve the sensing margin and to guarantee correct operation of sensing circuit for wide range of tunnel magneto resistance (TMR) voltages. In this scheme, the output voltage of the reference cell becomes nearly the midpoint between the cell voltages of high and low states even if the voltage across the magnetic tunnel junction (MTJ) varies.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.280-281
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• 2018

The methods for adjusting the output voltage as well as the heater temperature of a single-phase inverter for the heat treatment are proposed. The output voltage of the single-phase inverter is limited to 60 V for safety. The time constant of heater temperature is much higher than that of the output voltage. The stability may be deteriorated due to such large time constant difference. In order to ensure the stability, a hysteresis on/off control method for the heater temperature control is used. The performances for the proposed methods are verified with the experiments.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.85-92
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• 1996

The external electricla characteristics of helicon wave plasmas were measured over a wide range of RF power and magnetic filed. External parameters. such as antenna voltage , current, phase shift, and interanl parameter, electron density were measured at 7MHz, 1mTorr Ar discharge . The equivalent discharge resistance and reactance, and the power transfer efficiency were calculated through these measurements. There are a helicon mode which produces high density plasma by helicon wave and a lowmode which produces low density plasma by capaictive electric field. In case of the helicon mode, the anternna voltage and current were lower than those of the low-mode. The phase difference between voltage and current decreased suddenly at the transition point from the low-mode to the helicon mode. Equivalent resistance and power efficiency increased and reactance decreased suddenly at the transition point. These results mean that the power transperred to plasma and the nutual coupling between the antenna and plasma increase as the mode changes from the low-mode to the helicon mode.

• Transactions of the Korean hydrogen and new energy society
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• v.3 no.2
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• pp.63-69
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• 1992

Two unit cells were made and operated with oxygen and air as oxidants After 350 hours operation with oxygen, the open circuit voltage drop of unit cell was 30 mV and internal resistance increased. After 250 hours operation with air, the open circuit voltage drop was 130mV. And the open circuit voltage difference of two cases was 90mV. In order to improve the performance of the unit cell with air, the supplying method of the electrolyte and the mass transfer characteristics of the electrode should be studied.

• 전기의세계
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• v.28 no.1
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• pp.73-82
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• 1979

There are a great number of papers on the Townsend discharge in gases, and many of them are concerned with the effect of the cathode. It has been regarded that there are two kinds of effect of the electrodes, especially of the cathode; (a) the effect caused by the difference of the cathode material and (b) the effect by the change of the cathode surface state even in the same material. Both of them may change the secondary coefficient following after the change of the work function, and the atter may further change the primary ionization coefficient as foreign atoms on the surface may be dseorbed in sparks to decrease the purity of the gas. Thus the two effects must be investigated independently to study the roles of the cathode in gas discharges. In this report the effect of the cathode material on the sparking voltage is described. The experiment is also carried out under the condition that the desorption of impurities from the cathode be negligible. From these the new correlativity between the work function of the cathode and the sparking voltage is obtained. In addition, the interesting character of the minimum point of the Paschen's curve can be found.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.470-476
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• 1989

In order to develop a mathematical model which can predict the operating voltage and current of a discharge lamp, the properties and the physical phenomena of a low pressure gas discharge are investigated. Fluorescent lamp which uses a low pressure mercury-argon gas discharge is used in the model development. In a low pressure mercur-argon gas discharge, the continuity equation for each excited atom and electron, and the electron energy balance equation can predict the physical quantities of discharge. By coupling these equations and the circuit equation, the electrical characteristics of the discharge lamp can be predicted. To verify the validity of the suggested model, we calculated the voltage and current of a fluorescent lamp operating with inductor ballast for source frequency of 5KHz, 8KHz, 10KHz, and 13KHz. The results show good agreements in wave forms between the measured voltage and current, and the difference between the measured and calculated one is less than 5%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.20-25
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• 2006

We suggest a novel temperature detection method utilized in temperature monitoring system. Suggested method detects temperature variation by using $R_{ds(on)}$ characteristics of MOSFET, while conventional methods are using extra devices such as a temperature sensor or an over-temperature detection transistor. For voltage detection between drain and source, 10 bits resolution ADC is needed. Therefore possible measurement signal range is about ten mV. If detected temperature's voltage exceed protection temperature's voltage then controller generates OT (Over Temperature) signal to stop MOSFET's trigger signal. Whole process of measurement is controlled by software. Experimental results show that the developed temperature monitoring system can provide the suitable temperature monitoring method and difference between detected and data sheet value of the suggested system is about $3\%$.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.21-24
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• 2016

A junction box used in a 3 kW photovoltaic power generation system plays a role in collecting and supplying the direct current voltage produced by photovoltaic modules to an inverter. It is also used for facilitating maintenance checks and protecting the module and inverter by keeping the voltage constant. As for the junction box, using it in a parallel connection creates a difference between the setup modules. In order to compensate, an inverse voltage diode is used. But the high-power created through the solar generator can be delivered to the inverter through the inverter regularly. Therefore, a component can break down due to excess heat. And consequently short circuits and electric leakage occurs. In this study, using a junction box that enabled the bypass of high electric power, it was possible to reduce heat generation by approximately 35℃ when compared to a standard junction box.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.400-402
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• 2003

The inductive interference can be happened on some of the communication line that is located near by paralleled transmission line. The causes of inductive interference are magnetic coupling, capacitive coupling and residual voltage at neutral point of transmission line. In this paper, after grounding the one side of communication line, we have measured the voltage to ground at the other side of it. And we also have measured the voltage to ground at the end of it without grounding. As a result, we proved that the cause of inductive interference is the difference of ground voltages.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.264-266
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• 1994

In this paper, we describe the thermal distribution characteristics of 1 phase, 22.9kV 200kVA, pad mounted transformer. We made pad. tr. which had 71 temperature measuring points in windings and case. In the results of pad. tr. temperature distribution, the highest and the lowest temperature points are placed in the high voltage windings and the temperature difference of high voltage winding is higher than that of low voltage winding.