• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.547-554
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• 2013

Chlorine has strong oxidizing power, also it is many advantages over other disinfectants such as the residual characteristic and economic feasibility. However, chlorine also has disadvantages such as creating disinfection by-products of chlorine as THMs. In particular, the most deadly disadvantage of chlorine is that it is extremely poisonous toxins about all alive lives. Disinfection with electrolysis water can be a very useful way Because you do not have to worry about chlorine's dangerous. In this study, we evaluated the potential as a disinfectant, across the evaluating disinfection effect and generating characteristic of by-products. The electrolyzed water could be obtained removal efficiencies of over 99.9 % the coliform by operating condition such as residence time, current density (voltage), the electrode gap. The residual chlorine be generated 10,000 mg/L in current density $1.0A/dm^2$ and residence time of 10 minutes. The residual chlorine concentration was possible to maintain a stable. The by-products generated by high concentration residual chlorine in the reactor such as trihalomethanes, haloaceticacid, chloralhydrate, haloacetonitrile were detected in less than a water quality standards. At the concentration of less than residual chlorine of 1 ppm, the chlorine disinfection by-products be generated most below the detection limit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.74-83
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• 2002

The maximun short circuit current of modern power system is becoming so large that circuit breaker is not expected to be able to shut down the current in the future In order cut over-currents, a system composed of a superconducting fault current limiter(SFCL) and traditional breaker seems to provide a promising solution for furture power operation. In present paper, three line-to-ground fault is assumed to happen at the center of 345kV transmission lines in a large capacity electric power system. The superconducting fault current limiter was represented using a commutation type, which consists of a non-inductive superconducting coil and current limiting element (resistor or reactor). from the viewpoint of current limiting performance, the prevention of the voltage drop at the load bus and comparision characteristics for two type SFCL. Desired design specification and operation parameters of SECL were also given qualitatively by the performance.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.278-281
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• 2000

In this study, the electrical characteristics of 100V -Class LDMOSFET for high temperature applications such as electronic control systems of automobiles and motor driver were investigated. Measurement data are taken over wide range of temperature(300K-500K) and various drift region length(6.6$\mu\textrm{m}$-12.6$\mu\textrm{m}$). In high temperature condition(>450K), drain current decreased over 50％, and specific on-resistance increased about twice in comparison with room temperature. Moreover the ratio R$\sub$on//BV, a figure of merit of the device, increased with increasing temperature.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.13-16
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• 2002

In this study, the electrical characteristics of 100v-Class LDMOSFET for high temperature applicat -ions such as electronic control systems of automo -biles and motor driver were investigated. Measurement data are taken over wide range of temperature(300k-SOOK) and various gate length(1.5 #m-3.0#m, step 0.3). In high temperature condition(>500k), drain current decreased over 30%, and specific on- resistance increased about three times in comparison with room temperature. Moreover, the ratio ROJBV, a figure of merit of the device, increased with increasing temperature.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.85-93
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• 1996

The far-zone scattered field patterns of a hyperbolic reflector antenna are analyzed by using uniform geometrical theory of diffraction(UTD). The main objective of this paper is to obtain the higher order diffraction contributions which provide the continuity over the shadow boundaries of the first order solution. to obtain the scattered magnetic field characteristics, the scattered field components of the secodn-order diffraction, diffraction-reflection, diffraction-reflection-diffraction terms are added to the result of the previous research. The results of the present research are compared to those of the first order solution and the method of moments. One can observe the improvemtn of the current approach over the first order solution. also, the results of the present method agree very well with those of the moment methods especially in the transition regions near the first order diffraction shadow boundaries.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.201-204
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• 2001

LDMOSFET devices operated at low temperature have applications on satellite, space shuttle and low temperature system, etc. In this study, we measured the electrical characteristics of 100v Class LDMOSFET for low temperature application. Measurement data are taken over a wide range of temperatures (100K-300K) and various drift region lengths(6.6${\mu}{\textrm}{m}$, 8.4${\mu}{\textrm}{m}$, 12.6${\mu}{\textrm}{m}$). Maximum transconductance, $g_{m}$ and drain current at low temperatures(~100K) increased over about 260%, 50% respectively, in comparison with the data at room temperature. Breakdown voltage B $V_{ds}$, and specific on- resistance decreased. Besides, ratio $R_{on}$ BV, a figure of merit of the device, decreased with decreasing temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.3
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• pp.197-204
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• 2008

DMFC(Direct Methanol Fuel Cell) is one of promising candidates for power sources of small mobile IT devices like notebook, cell phone, and so on. Efficient operation of fuel cell system is very important for long-sustained power supply because of limited fuel tank size. It is necessary to investigate operation characteristics of fuel cell stack for optimal control of DMFC system. The generated voltage was modeled according to various operating condition; methanol concentration, stack temperature, and load current. It is inevitable for methanol solution at anode to cross over to cathode through MEA(membrane electrode assembly), which reduces the system efficiency and increases fuel consumption. In this study, optimal operation conditions are proposed by analyzing stack performance model, cross-over phenomenon, and system efficiency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.5
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• pp.536-541
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• 1988

The push-pull current-fed DC-to-DC converter has only one energy storage reactor in series with the input for any number of outputs. It is considered that this property of the converter has considerable advantages over other multiple-output circuits. The steady state characteristics of the converter with two outputs is analyzed. It is known that the voltage difference between the two outputs appears by existing the 2nd winding resistance of transformer and there is a region of the duty ratio in which the voltage difference of the converter is smaller than that of the forward converter.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1582-1584
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• 2004

The microstructure, electrical, and clamping voltage characteristics of ZPCCY-based varistor ceramics were investigated in the sintering time range of 1${\sim}$3 h. Increasing sintering time promoted the densification, in which the average grain size and density are increased in the range of $11.4{\sim}16.0{\mu}m$ and $5.34{\sim}5.54g/cm^3$, respectively. The nonlinear exponent decresed in the range of 60${\sim}$26 and the leakage current increased in the range of $1.3{\sim}10.7{\mu}A$ with increase of sintering time. The clamping voltage ratio was less than 2 for ratio surge current of 10 A over sintering times.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.43-46
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• 2001

The ZnO devices using semiconductor properties, to include $MnO_2$, $Y_2O_3$ and other material, was fabricated by $Sb_2O_3$ mol ratio from 1 to 4 [mol%]. The non-linearity factor was calculated by setting current to be $1[mA/cm^2]$ and $10[mA/cm^2]$. The spinel structure was fonned by $Sb_2O_3$ addition and it was depressed the ZnO grain formation. The grain growing was controlled by spinel structure that has improved the non-linearity factors. The breakdown voltage characteristics of semiconductor devices to increase with $Sb_2O_3$ was increased in voltage-current. The non-linearity value of ZnO semiconductor devices was 45 over.