• Journal of Power Electronics
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• v.14 no.4
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• pp.742-753
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• 2014

In this paper, a new continuously and linearly controlled capacitive static VAR compensator is proposed for the automatic power factor correction of inductive single phase loads in 220V 50Hz power system networks. The compensator is constructed of a harmonic-suppressed TCR equipped with a new adaptive current controller. The harmonic-suppressed TCR is a new configuration that includes a thyristor controlled reactor (TCR) shunted by a passive third harmonic filter. In addition, the parallel configuration is connected to an AC source via a series first harmonic filter. The harmonic-suppressed TCR is designed so that negligible harmonic current components are injected into the AC source. The compensator is equipped with a new adaptive closed loop current controller, which responds linearly to reactive current demands. The no load operating losses of this compensator are negligible when compared to its capacitive reactive current rating. The proposed system is validated on PSpice which is very close in terms of performance to real hardware.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1189-1196
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• 2001

When fluid flows at high speed over an open cavity, large acousitc pressure is produced by fluid/structure interaction at the downstream edge of the cavity. The goal of this paper is suggestion of effective control method to suppress the noise generated from cavity and numerically simulation of active control. The cavity instability mechanism is simulated and a close-loop control algorithm is implemented. The effects of the actuator and some control function are discussed. The compressible Navier-Stokes equations are solved with the high-order and high-resolution numerical schemes to precisely simulate the interaction between flow and acoustic. The results show that noise is effectively suppressed with the control method suggested in this paper.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.187-193
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• 1998

An inverter-driven induction motor is used as the traction motor for a high speed drive system that required safty, reliability and performance and so on. rotor bar and end ring of the traction motor are the electrical equipments which form the conductive close loop and then induce current by interaction wi th the current of stator. the materials selection of rotor bar and end ring are seriously considered in the aspects of electrical and mechanical specification and Motor slip relation to inverter. Particularly motor slip guarantee the safty and reliability of induction motor. this paper show the material selection and the determining of slip in the design of traction motor for high speed train by analyzing the specifications of material being used currently.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.579-587
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• 1999

The flow distribution characteristics in a complex duct system have been investigated in this paper by three means, namely experimental measurement, numerical simulation and the Extended T-method analysis. While the exit flow rates predicted by the three-dimensional CFD calculation and those given by the experiment show a close agreement, the results from the one-dimensional Extended T-method are found to differ from the experiment by -22.2% to 26.3% for the various exits. These discrepancies may be attributed to the underlying limitation concerning the fitting loss coefficients, which assume that the flow in front of the fittings is fully developed. It is proposed that, in order to analyse the three-dimensional flow distributions in a complex duct system by one-dimensional analysis such as the Extended T-method, further Improvements to the fitting loss coefficients should be made.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1993.06a
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• pp.765-768
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• 1993

Adaptive Control is used in order to improve close loop dynamics with a fuzzy controller when process parameters are unknown or fluctuate form an initial value. The way in which the adaptive control environment may be applied is the following. First we obtain a linear fuzzy controller. Second, we apply the adaptive rules by means of actuating directly over fuzzy variables which change their value. The techniques are based on Lyapunov functions. Third, we comment about extending this method to non-piecewise linear controllers using the contrast definition for a fuzzy controller.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1117-1125
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• 2007

In this paper, a study has been performed on the design of small loop probe and analysis of induced electromagnetic wave signal from a smartcard for contactless cryptographic analysis. Probes for cryptographic analysis are different from conventional EM probes, because the purpose of proposed probe is to obtain the information for secret key analysis of cryptographic system. The waveform of induced voltage on probe must be very close to radiated waveform from IC chip on smartcard because electromagnetic attack makes an attempt to analyze the radiated waveform from smartcard. In order to obtain secret key information, we need to study about cryptographic analysis using electromagnetic waves, an approximate model of source, characteristic of probe for cryptographic analysis, measurement of electromagnetic waves and calibration of probes. We measured power consumption signal on a smartcard chip and electromagnetic wave signal using proposed probe and compared with two signals of EMA point of view. We verified experimently the suitability of the proposed small loop probe for contactless cryptographic analysis by applying ARIA algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.17-23
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• 2004

The implementation and design of the wideband IFIU using aperture open loop resonator and reversed phase technique to reduce the local oscillator leakage signal was represented in this paper. The local oscillator leakage signal is generated in stage of frequency conversion, especially in frequency conversion of fully digital modulation signal close to DC signal. The leakage signal and spurious signals, which have effects on adjacent channel or in-band channel as interference signals, were reduced below -60 dBc for 45 Mbps and 155 Mbps IF interface units. The group delay for both IFIUs shows low ripple characteristics of 15 ns and 8 ns, respectively. Also, the amplitude ripple characteristic in 150 MHz bandwidth with L-band center frequency satisfies the required specification of 2 dB. The implemented IFIU provides the required specifications for wideband satellite communication system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.463-472
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• 2017

Inertial Navigation System Alignment is the process to determine direction cosine matrix which is the transformation matrix between the INS body frame and navigation frame. INS initial position value is necessary to INS attitude calculation, so that user should wait until he get such value to start the INS alignment. To remove the waiting time, we propose an alignment algorithm that immediately starts after the INS power on by using pseudo initial position input and then is completed with attitude error compensation by entering true position later. We analyse effect of INS sensor error on attitude in process of time and verify the performance and usefulness of the close-loop alignment algorithm which corrects attitude error from the change of initial position.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.12
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• pp.965-971
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• 2003

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. For this system. we have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce milliactuator and controller design method, PQ method. PQ method reduces the controller design problem for DISO (dual-input/single-output) systems to two standard controller design problems for SISO ( single-input/single-output) problems. The first part of PQ method directly addresses the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.3
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• pp.171-180
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• 2010

Analysis on the temporal variation of the stratification is carried out by using the continuous water temperature and salinity data observed in the coastal monitoring buoy in Mikawa Bay, Japan. The main analysis results are as follows. The stratification pattern have an obvious and dominant 1-year period variation and the occurrence frequency (days) are exponentially decreased as the stratification intensity (SI) defined as the density difference between surface and bottom layers linearly increases. The frequency distribution function of the SI is presumably close to the log-normal function type or exponential function type. From the water temperature and salinity scatter diagram analysis, the line and loop type patterns are shown in the bottom and surface layers, respectively. In addition, the analysis of the SI estimation show that the error bound in case of using the weekly-monitoring data is about 4.45 times greater than that in case of using the continuous (daily) monitoring data.