• Journal of Drive and Control
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• v.10 no.3
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• pp.1-6
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• 2013

Traction control suppresses the spinning of the driven wheel during drive away or acceleration on slippery road condition. In this study, the estimation method of brake pressure hardly measured is proposed. The estimation method of brake pressure and the brake pressure control with pulse width modulation(PWM) are verified a good performance through experiment. Also, the vehicle simulation on slippery road conditions is validated the applicability of brake pressure control for traction control. The simulation results have showed that the brake pressure can be used the control variable for traction control.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2002.11a
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• pp.3-8
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• 2002

A new Modem technique - 8-state Superposed QAM(8SQAM) - for use in power and bandwidth limited digital communication system is proposed. The premodulation baseband signal of the 8SQAM system is a double-interval(2Ts) raised cosine pulse superposed with weighted single-interval(Ts) raised cosine pulse. The performance of the 8SQAM, in a nonlinearly amplified multi-channel environment with additive white Gaussian noise(AWGN), inter-symbol interference(ISI), inter-modulation(IM) and adjacent channel interference(ACI), is analyzed via computer simulation. The simulation result shows that the 8SQAM outperforms 8PSK by about 1.6㏈ at BER=$1\times10^{-4}$ when HPA IBO is 1㏈ and channel Spacing, ${\Delta}F$ is 0.417fb.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.533-535
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• 2007

The design of tunned filters for six-pulse thyrister converter is discussed. For electrolyzer system, the design procedure of tunned filters of AC 14.4kV power system are proposed by dynamic simulation. It is shown that these harmonic filters can meet most operational requirments. By careful specification of the transformer reactance, very low harmonic content and high power factor may be achieved at a specific operating point. The the proposed design procedure is verified with the simulation results.

• Journal of Power Electronics
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• v.11 no.3
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• pp.375-380
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• 2011

A STATic synchronous COMpensator (STATCOM) is a shunt connected voltage source converter (VSC) based FACTS controller using Gate Turn Off (GTO) power semiconductor devices employed for reactive power control. The operation principal is similar to that of a synchronous condenser. A typical application of a STATCOM is voltage regulation at the midpoint of a long transmission line for the enhancement of power transfer capability and/or reactive power control at the load centre. This paper presents the modeling of STATCOM with twenty four pulse three level VSC and Type-1 controller to regulate the reactive current or the bus voltage. The performance is evaluated by transient simulation. It is observed that, the STATCOM shows excellent transient response to step change in the reactive current reference. While the eigenvalue analysis is based on D-Q model, the transient simulation is based on both D-Q and 3 phase models of STATCOM (which considers switching action of VSC).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.7
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• pp.1061-1068
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• 2012

In this paper, The Next Generation High Speed Railway inverter system using Hybrid Random Pulse Width Modulation (Hybrid RPWM) is proposed to reduce electromagnetic noise. To verify the validity of study, simulation results of the Next Generation High Speed Railway Inverter system using the proposed method was compared with the system using conventional method. A simulation program is developed using Matlab/Simulink. The results show that the voltage and current harmonics of the Next Generation High Speed Railway Inverter system using Hybrid RPWM significantly decrease and spread into wide band area.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1503-1505
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• 2005

The Cold cathode fluorescent lamp(CCFL) are widely used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. Dimming methods of CCFL are used to pulse frequency modulation(PFM) or pulse width modulation(PWM). In this paper, CCFL driving and control circuit is designed by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output voltage current. The validity of this study is confirmed from the simulation and experimental results.

• The Journal of Natural Sciences
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• v.1
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• pp.21-31
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• 1987

A pulse shape of a pulsed TEA $CO_2$ laser in analyzed theoretically by the use of Computer simulation. Since the laser operates $10.6\mum$ P-20 line, regular band, the pulse shape is obtained by adding the hot band R-23 effect to the regular band $10.6\mum$ P-20. The results are well agreed to the experimental results.

• Korean Journal of Optics and Photonics
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• v.29 no.1
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• pp.32-39
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• 2018

The impact of the amplified spontaneous emission (ASE) on the gain recovery time of a bulk semiconductor optical amplifier (SOA) is investigated. The gain-recovery time is obtained by determining the time evolution of the gain, carrier density, and ASE in an SOA, after the propagation of a short pump pulse and continuous-wave (CW) probe of gain dynamics. In the simulation, a wide-band-semiconductor model, which can be characterized by the material gain coefficient over a wide wavelength range, is used, because the gain bandwidth of a practical SOA is very wide. The pump pulse and counterpropagating CW probe field are considered in the simulation, with the ASE noise spectrum equally divided.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.251-259
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• 1996

Two-Photon Fluorescence (TPF) experiment measures temporal width of an amplified short laser pulse which has passed through a four-pass Nd: glass amplifier, after selecting a single pulse from pulse train Q-switched and mode-locked(QSML) in Nd:YLF master oscillator. Determination of pulsewidth and pulseshape was also made with detection of autocorrelation trace of CW mode-locked pulse train by using noncollinear type I Second Harmonic Generation (SHG) method. The observed TPF track showed various patterns, depending on pulse-selecting position in QSML pulse train. That is, autocorrelation of a pulse extracted at front of the train displayed smooth pulse shape, while one from the trailing part of the train created many sharp spikes and substructure in the pulse. By TPF method, pulsewidth was measured to be 44.4 ps with contrast ratio of 2.86 which enabled us to find out energy fraction of a pulse to total energy, (sum of pulse and background); we obtain the value of 0.62. Pulsewidth of 46.6ps was also acquired in another SHG experiment with the help of only mode-locked pulse train. On the other hand, we confirmed that shape of the pulse is close to $sech^2$ one as a result of fitting the SHG autocorrelation signal with various functions. With simulation using this $sech^2$ type of pulse, pulsewidth reduction of the beam, having passed through four-pass amplifier, was also verified.

• Journal of Radiation Protection and Research
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• v.42 no.1
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• pp.48-55
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• 2017

Background: Simultaneous detection of neutrons and gamma rays have become much more practicable, by taking advantage of good gamma-ray discrimination properties using pulse shape discrimination (PSD) technique. Recently, we introduced a commercial CLYC system in Korea, and performed an initial characterization and simulation studies for the CLYC detector system to provide references for the future implementation of the dual-mode scintillator system in various studies and applications. Materials and Methods: We evaluated a CLYC detector with 95% $^6Li$ enrichment using various gamma-ray sources and a $^{252}Cf$ neutron source, with validation of our Monte Carlo simulation results via measurement experiments. Absolute full-energy peak efficiency values were calculated for gamma-ray sources and neutron source using MCNP6 and compared with measurement experiments of the calibration sources. In addition, behavioral characteristics of neutrons were validated by comparing simulations and experiments on neutron moderation with various polyethylene (PE) moderator thicknesses. Results and Discussion: Both results showed good agreements in overall characteristics of the gamma and neutron detection efficiencies, with consistent ~20% discrepancy. Furthermore, moderation of neutrons emitted from $^{252}Cf$ showed similarities between the simulation and the experiment, in terms of their relative ratios depending on the thickness of the PE moderator. Conclusion: A CLYC detector system was characterized for its energy resolution and detection efficiency, and Monte Carlo simulations on the detector system was validated experimentally. Validation of the simulation results in overall trend of the CLYC detector behavior will provide the fundamental basis and validity of follow-up Monte Carlo simulation studies for the development of our dual-particle imager using a rotational modulation collimator.