• Journal of the Society of Naval Architects of Korea
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• v.60 no.2
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• pp.76-85
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• 2023

The present study aims to review the wave pattern resistance analysis method suggested by the International Towing Tank Conference. From the experimental database of a container carrier ship model, the wave pattern measurement and resistance test results are utilized. The wave pattern resistance at the design Froude number is obtained to be compared with the wave making resistance of experiments. Wave pattern resistance is lower than wave making resistance by 1978 ITTC and uniform regardless of transverse location of wave cut. The method is also applied to the wave height field by Computational Fluid Dynamics (CFD) analyses with Froude number variation. Although numerical damping suppressed waves in downstream, waves around the hull and wave pattern resistance are properly predicted.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.228-229
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• 2009

$VO_2$ thermistor was fabricated on $Al_2O_3$ substrate. and has a CTR (Critical Temperature Resistor) characteristic. $VO_2$ thermistor has a about $10^6$ resistance($\Omega$) in normal temperature. But When temperature is a about $80^{\circ}C$, Resistance of $VO_2$ thermistor is a about some hundred resistance: The resistance of $VO_2$ thermistor increased with increasing length and decreasing width.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.1
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• pp.13-21
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• 2004

In the design of superconducting cable systems, quench analysis have to be advanced for applying to a real systems. It is necessary to calculate the current, voltage and resistance during the quench. Simulation program named EMTDC was used to analyze the quench state. Normal zone evaluation and quench development with EMTDC are one of the major features of quench analysis. This paper presents the two kinds of quench control models which are the Switch Control Type and the Fortran Control Type. In case of the quench developing area, the simplicity cable model consist of resistance, inductance and capacitance. The impedance of the pipe type superconducting cable is calculated by numerical analysis method. The resistance and inductance increased during quench. However the variation have an effect on the fault current. The voltage was also developed by resistance and inductance. This paper presents the relationship between the current. voltage, resistance and inductance during quench.

• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.86-93
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• 1998

In this paper, we propose an effective on-line identification method for rotor resistance, which is useful in making speed control of induction motors without rotational transducers robust with respect to the variation in rotor resistance. Our identification method for rotor resistance is based on the linearly perturbed equations of the closed-loop system for sensorless speed control about th operating point. Our identification method for rotor resistance uses only the information of stator currents and voltages. In can provide fairly good identification accuracy regardless of load conditions. Some experimental results are presented to demonstrate the practical use of our identification method. For our experimental work, we have built a sensorless control system, in which all algorithms are implemented on a DSP. Our experimental results confirm that our on-line identification method allows for high precision speed control of commercially available induction motors without rotational transducers.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.454-457
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• 2008

Effects of patenting temperature on bending fatigue resistance of pearlitic steel filaments were investigated experimentally. The fatigue resistance of steel filaments was carried out by using hunter machine, specially designed for ultra fine-sized steel wires, in the controlled conditions. The transmission electron microscopy (TEM) was used for observing the overall microstructure. It revealed that the fatigue resistance as well as tensile strength increased together with increase of patenting temperature from 510 to $600^{\circ}C$, while the endurance ratio ($\sigma_e/\sigma_{TS}$) of filaments decreased. It is believed that this variation of mechanical properties with change of patenting temperature should be strongly influenced by the change of microstructure. The bending fatigue properties of steel filaments were discussed based on microstructural parameters.

• Steel and Composite Structures
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• v.27 no.6
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• pp.777-788
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• 2018

An investigation on the thermal buckling resistance of simply supported FGM beams having parabolic-concave thickness variation and temperature dependent material properties is presented in this paper. An analytical formulation based on the first order beam theory is derived and the governing differential equation of thermal stability is solved numerically using finite difference method. a function of thickness variation is introduced which controls the parabolic variation intensity of the beam thickness without changing its original material volume. The results showed the high importance of taking into account the temperature-dependent material properties in the thermal buckling analysis of such critical beam sections. Different Influencing parametric on the thermal stability are studied which may help in design guidelines of such complex structures.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.57-59
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• 2001

We investigated the maximum controllable current characteristics of the CB-BRT (Corrugated p-Base-Base Resistance Controlled Thyristor), which suppresses the snap-back effectively and increases the maximum controllable current(MCC) by employing the corrugated p-base. Experimental result shows that, when compared with conventional BRT, the MCC of the CB-BRT exhibits good stability on various process parameters. The MCC of the CB-BRT is larger than that of the conventional BRT by 50%, and the variation of the MCC in CB-BRT, caused by variation of the process parameters, is only 20% of that of the conventional BRT.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.372-377
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• 2007

This paper proposes a novel fault diagnosis method of a electrolytic capacitor used for DC-link voltage smoothing in adjustable speed drives. The equivalent series resistance (ESR) of the electrolytic capacitor is directly estimated from DC-link voltage and load currents and the status of the electrolytic capacitor is determined from the estimated ESR. To compensate the variation of the ESR owing to temperature variation, diodes are located on the same PCB near the capacitor and the temperature of the capacitor is sensed indirectly from the voltage drop of diodes. Simulation and experimental studies show the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.162-166
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• 2000

In this paper, a maximum efficiency control technique of real-time processing in which parameter variation is compensated in vector control of an induction motors(I.M.) is proposed. Based on equivalent model of I.M., a loss minimization factor(LMF) with the variations of speed is derived. To solve problem of inaccuracy of LMF curves due to machine parameter variation, rotor resistance estimation is performed by using instantaneous reactive power. The estimated rotor resistance values are applied to the maximum efficiency control with a LMF.

• Journal of the Korean Ceramic Society
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• v.18 no.2
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• pp.119-125
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• 1981

The thermostable resistor was made by using P.T.C.R-N.T.C.R. ceramics. In this study $BaTiO_3$ type P.T.C.R. ceramics and $SnO_2-Sb_2O_3$ type N.T.C.R. ceramics were cocrystallized in one body and electrical resistance was stable under the temperature variation between $25^{\circ}C$-40$0^{\circ}C$. The ceramics showed the most stable electrical resistance for the mal variation when the composition was 0.6P.T.C.R. $BaTiO_3$,$ 0.4SnO_2$ and 0.01 $Sb_2O_3$.