• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1279-1284
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• 2008

This paper presents the operating characteristic of high voltage impulse(HVI) track circuit owing to the ill-contact of impedance bond lead wire. The characteristic operations of the track include rail voltage and current. Measurements are carried out using oscilloscope with current probe and it analyzed the abnormal operation due to connector of protective wire. Finally, suitable track circuit is proposed for conventional line, and operating characteristic of HVI track circuit is affected by bypass circuit.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.167-174
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• 2008

In this paper, the analysis on type effect of inverter output voltage distortion on the control of an induction motor is discussed. The inverter output voltage is distorted differently from the reference voltage owing to the inverter nonlinear characteristic. The inverter nonlinear characteristic results from the voltage drop, the inherent characteristic of the power semiconductor, and the dead time for preventing the short circuit of the inverter leg. This characteristic distorts the inverter output voltage and then, causes the motor flux estimation error. Although this characteristics do not significantly effect in the general-purpose induction motor control, but significantly effect on the low-speed operation of high performance motor control such as the sensorless vector control.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1017-1022
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• 2015

Specific hydrodynamic characteristic of pump-turbine during the start and load rejection process of generating mode causes anomalous increase of water pressure, along with large machine vibration, called "S" characteristic. The aim of this study is to understand and explain the hydrodynamic performance of pump-turbine at "S" characteristic region by using a model of pump-turbine system. The operation in the condition of runway and low discharge in a typical "S" characteristic curve may become unstable and complex flow appears at the passage of guide vane and impeller. Therefore, velocity and pressure distribution are investigated to give an all-sided explanation of the formation and phenomenon of this characteristic, with the assistance of velocity triangle analysis at the impeller inlet. From this study, the internal flow and pressure fluctuation at the normal, runway and low discharge points are explored, giving a deep description of hydrodynamic characteristic when the pump-turbine system operates with "S" characteristic.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.817-820
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• 2006

The Tonpilz transducer is one of the essential elements in active sonar application. The characteristics of transducer depend on the piezoelectric ceramics and mechanical elements such as head mass, tail mass, pre-stress rod and so on. One of the important characteristics is electric and mechanical stability of transducer for long term high power transmitting operation. This parer presents the results about long term endurance tests of the underwater acoustic transducer.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.128-130
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• 2002

This paper describes the operating characteristic analysis of magnetic actuator that is used in breaker using 3-D axisymmetry finite element method. To analyze the operating characteristic of magnetic actuator for configuration change is designed an A, B model and C. Also, For Transient analysis of Electromagnetic system is considered Non-linear characteristic for magnetizing of iron. The analysis results of A, B model and C for magnetic actuator compared with those characteristic respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.995-999
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• 2007

We investigated the characteristics of a flux-lock type superconducting fault current limiter(SFCL) considering magnetization characteristic of iron core. The flux-lock type SFCL, like other types of SFCLs using the iron core, undergoes the saturation of the iron core during the initial fault time. Therefore, if the design to prevent the saturation of the iron core is considered, the effective fault current limiting operation can be achieved. Through the analysis for its equivalent circuit including the magnetization characteristic of the iron core, the limiting impedance of the flux-lock type SFCL was drawn. The magnetization currents and the limited currents of SFCL, which were dependent on the winding direction and the turns' ratio between two coils, were investigated from the short circuit experiment. It was confirmed that their experimental results agreed with the analysis ones.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.209-214
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• 2007

This study is concerned with working hardening of bending operation on hydroforming parts. Generally, hydroforming parts having the complicated shape of the automobile, require a 3-dimentional bending operation. This operation involves several variations in the tube which are the thickness, the mechanical characteristics, the hardness, the circumference etc., on original tube. So, we study those variations and the affect on the hydroforming operation and hydroforming parts. We used two methods, one of which was computer simulation and the other the actual test in the plant.

• Korean Journal of Remote Sensing
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• v.19 no.1
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• pp.37-42
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• 2003

Recently, KARI implemented the receiving and processing system for MODIS sensor data from NASA EOS satellites (TERRA and AQUA). This paper shows the development strategy considered, system requirement derived, system design, characteristic and test results of processing system. System operation concept and sample image are also provided. Implemented system was proven to be fully operational through lots of pass operations activities from RF signal reception to level-1 processing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.4
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• pp.643-650
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• 2017

This pap4er analyzes resonance characteristics of a slave motor that is not controlled by load and parameter differences between Dual motors during parallel operation in middle-low speed. Dual SPMSMs(Surface mounted Permanent Magnet Synchronous Motor) connected in parallel to a single inverter controlled by the master and slave control in this paper. Based on the stability analysis of the SPMSM for a variation of torque angle, the 6th nonlinear state equation of the torque angle variation in the SIMM(Single Inverter Multi Motor) structure is derived according to a mathematical model for the dual motors. In general, an analysis of the 6th order nonlinear state equation is complex. Therefore, a resonance frequency generated from the slave motor is found from the characteristic equation of the 2nd order system obtained by linearization and model reduction near steady state operation point. Through simulations and experiments, it is confirmed that the stability analysis of the SPMSMs and state equation models are useful for the variation of the torque angle analyzed in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.238-240
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• 2017

Balun using a coaxial lines i often used in microwave circuits due to easy fabrication, high operating power, and stable operation. However, it is difficult to predict an accurate balun operation characteristic due to the parasitic reactance component to be generated when the coaxial line is connected to the microstrip line existing on the substrate, and the inductance and the capacitance component of the coaxial line itself. In this paper, it is measured the phase characteristics at two output ports of the coaxial line balun which should have opposite phase characteristics. Based on these results, it will examine closely the feasibility of making more improved coaxial line balun.