• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.494-500
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• 2008

This paper presents the analyzed result of the series arc fault current by using the discrete wavelet transform. The series arcing is caused by a loose connection in series with the load circuit. The series arc current is limited to a moderate value by the resistance of the device connected to the circuit, such as an appliance or a lighting system. The amount of energy in the sparks from the series arcing is less than in the case of parallel arcing but only a few amps are enough to be a fire hazard. Therefore, it is hard to detect the distinctive difference between a normal current and a intermittent arc current. This paper, presents the variation of the ratio of peak values and RMS values of the series arc fault current, and proposes the novel series arc fault detecting method by using the discrete wavelet transform. Loads such as a CFL lamp, a vacuum cleaner, a personal computer, and a television, which has the very similar normal current with the arc current, were selected to confirm the novel method.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.173-181
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• 2017

In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.951-957
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• 1994

We present a new model for the series resistance of inverted-staggered amorphous silicon (a-Si) thin film transistors (TFT's) by employing the current spreading under the source and the drain contacts as well as the space charge limited current model. The calculated results based on our model have been in good agreements with the measured data over a wide range of applied voltage, gate-to-source and gate-to-drain overlap length, channel length, and operating temperature. Our model shows that the contribution of the series resistances to the current-voltage (I-V) characteristics of the a-Si TFT in the linear regime is more significant at low drain and high gate voltages, for short channel and small overlap length, and at low operating temperature, which have been verified successfully by the experimental measurements.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.84-98
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• 1990

Fifteen(l5) series hull forms for full slow-speed ships were prepared by expanding the basic parent hull form developed through the extensive theoretical and experimental studies, and model tests were carried out for each of the series hull forms. A set of systematic data was prepared from the test results and utilized to derive regression equations for the prediction of resistance and powering characteristics by statistical analysis. Computer program has been prepared based on the results of analysis and a sample run is presented.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.2
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• pp.92-98
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• 2002

It is necessary to measure the solar cell parameter fur understanding characteristic of solar cell and applying to many other fields. Since photovoltaic system consists of solar cell module, which are connected each other in series and parallel, it is not proper to apply a solar cell parameter to photovoltaic system. Therefore, to estimate the solar tell module and to solve the problem of the established algorithm is on demand. In this paper the authors have improved the accuracy of solar cell module Parameter estimation by compensating series and Parallel resistance, and developed a new parameter estimation algorithm, which can be applied to photovoltaic system without high cost measuring equipment. And the validity of proposed algorithm is verified by the simulation and experimentation.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.817-827
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• 2016

The resistance in series model has been frequently used for determination of various filtration resistance to correctly understand the membrane fouling behaviour in MBR (membrane bio-reactor) for wastewater treatment. The cake layer resistance ($R_c$) which is commonly determined by calculation of flux dataset that are obtained empirically before and after removing the cake layer on membrane surface. However, the calculated Rc values are very dependent on the cleaning methods adapted for removal of cake layer. This study investigated how the various cleaning options affect $R_c$. Seven different cleaning methods were employed: i) ultrasonication (100 W, 10 min), ii) ultrasonication (200 W, 60 min), iii) ultrasonication (400 W, 120 min), iv) water rinsing in a shaker (100 rpm, 10 min), v) water rinsing in a shaker (300 rpm, 60 min), vi) water rinsing, vii) sponge scrubbing. For the hydrophilic PES membrane, the cake layer removal efficiencies ranged from 64% to 10%, indicating that the removal of cake layer was highly dependent on the cleaning options. For the hydrophobic PVDF membrane, the cake layer removal efficiencies ranged from 79% to 97%. Consequently, a standardized method for cake layer removal to determine cake resistance ($R_c$) is needed for correct interpretation of the fouling phenomena.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.1
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• pp.24-31
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• 2018

An induction heating (IH) resonant converter, as well as its coil design method, is proposed in this study to improve the heat capability of low- and high-resistance IH vessels. Conventional IH resonant converters have been designed only for heating high-resistance containers designed for IH application. Thus, the primary current in the resonant tank becomes extremely high to transfer the rated power when the converter heats the low-resistance vessel. As a result, the rated power cannot be transferred due to overcurrent flows against the rated switch current. Hence, the optimal number of coil turns and proper operating frequency to heat high- and low-resistance vessels are proposed in this study by analyzing an IH load model. Simulation and experimental results using a 2.4 kW prototype resonant converter and its IH coil validate the proposed design.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.300-300
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• 2010

후면 패시베이션, back contact의 가변, 후면 접촉면적의 가변 등으로 Laser Fired Contact 태양전지의 효율을 증가 시킬 수 있다. 이 중 spacing의 가변으로 후면 접촉 면적을 가변 할 수 있으며, 이로 인하여 LFC 태양 전지의 효율을 높일 수 있을 것으로 전망된다. 본 연구에서는 후면 접촉 면적을 가변하였으며 이에 따른 효과를 확인하였다. series resistance가 작고, open circuit voltage 가 높은 최적의 조건을 찾는 것에 그 목적을 두었다. 실험 순서는 texturing 후, 후면에 SiNx를 10nm 증착하였으며, drive-in 방법으로 $POCl_3$을 도핑하였다. ARC후, spacing 조건 가변으로 접촉 면적을 가변시키면서 소자의 특성 변화를 비교하였다. 접촉 면적 및 spacing 조건은 5개의 set에 대하여 reference, 50%의 접촉 면적을 가지는 $150{\mu}m$ line, 10%의 접촉 면적을 가지는 $700{\mu}m$ line, 1%의 접촉 면적을 가지는 $700{\mu}m$ dot, 그리고 0.2%의 접촉 면적을 가지는 $1500{\mu}m$ dot으로 하였다. 각각의 경우에 대한 short circuit current density, fill factor, seris resistance, sheet resistance, open circuit voltage를 측정하였으며, 특히 series resistance는 각각의 경우에 대하여 $6.1m{\Omega}$, $5.1m{\Omega}$, $7.8m{\Omega}$, $10.1m{\Omega}$, 그리고 $15.7m{\Omega}$으로 측정되었다. wafer의 외각 테두리를 접촉 면적이 증가함에 따라서 sheet resistance가 증가하는 것을 확인 할 수 있었다.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.2
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• pp.28-39
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• 1991

A study on the optimization problems to find forebode shapes with minimum wavemaking and frictional resistance was performed. The afterbody was fixed as a given hull and only forebode offsets were treated as design variables. Design variables were divided into the offsets of given hull and small variation from them. For the wavemaking resistance calculation, Neumann-Kelvin theory was applied to the given hull and thin ship theory was applied to the small variation. ITTC 1957 model-ship correlation line was used for the calculation of frictional resistance. Hull surface was represented mathmatically using shape function. As object function, such as wavemaking and frictional rersistance, was quadratic form of offsets and constraints linear, quadratic programing problem could be constructed. The complementary pivot method was used to find the soulution of the quadratic programing problem. Calculations were perfomed for the Series 60 $C_{B}$=0.6. at Fn=0.289. A realistic hull form could be obtained by using proper constraints. From the results of calculation for the Series 60 $C_{B}$=0.6, it was concluded that present method gave optimal shape of bulbous bow showing a slight improvement in the wave resistance performance at design speed Fn=0.289 compared with the results from the ship theory only.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.85-91
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• 2011

Many protection methods such as surface coating, electric protection, or other methods have been applied to the numerous steel structures widely used in continental and marine areas to control their corrosion, which is done from an economic point of view. Most of these steel structures are primarily protected by coating methods. However, some steel piles under seawater are protected by the electric protection method, that is, either using an impressed current or a sacrificial anode method. Furthermore, environmental contamination may cause a severely corrosive environment, which, in turn, causes the accelerated corrosion of steel structures. Subsequently, coated steel structures could deteriorate more rapidly than the designed lifetime because of the acid rain caused by air pollution, etc. Therefore, a coating of marine paint exposed to seawater, that is, underwater hardening painting, is increasingly required to be fast drying as well as highly corrosion resistant. In this study, five types of underwater hardening paints were prepared with different resin series and additives. Their corrosion and water resistances were investigated using electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements, etc. Even though it is generally accepted that the corrosion resistance of bare steel tends to increase with a shift of the corrosion potential in the noble direction, the corrosion resistance of a sample with a coating exhibited a relatively better tendency when it had a lower corrosion potential in this study. The corrosion current density was also decreased with a decrease in the diffusion limiting current density, which may mean that there is some relationship between corrosion and water resistance. The S sample of the ceramic resin series showed the relatively best corrosion and water resistance among those of samples, while the worst corrosion and water resistance were observed for the R sample of the epoxy resin series. The corrosion and water resistance of those samples tended to deteriorate with an increase in the immersion days, and their corrosion and water resistances were considered to be apparently improved by the types of resin and additives.