• 한국정보기술학회 영문논문지
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• 제9권1호
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• pp.11-24
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• 2019

This paper investigates the performance comparison of a Terahertz (THz) communications for a single-carrier and a multi-carrier single antenna point-to-point communication system. The multi-carrier system and single carrier system consider the orthogonal frequency division multiplexing (OFDM) and the minimum mean square error linear equalizer (MMSE-LE), respectively. We compare the frame-error-rate (FER) and throughput performance of both the systems for a THz communication environment with the carrier frequency of 300GHz and the tapped delay line (TDL) channel models described in 3GPP. It is observed from the simulation results that the OFDM systems outperform the MMSE-LE for various configurations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.512-517
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• 1998

In a matrix converter, input side and output side are coupled with each other through switching elements. Since disturbances on either side affect directly on the other side, it requires a high-speed on-line control system to compensate them. We proposed in previous papers a new control strategy and an on-line control circuit for a matrix converter. The control circuit could keep the output voltage at commanded value against fluctuation in the supply voltage. Furthermore wave forms of the output voltage and the input current were always kept sinusoidal. The switching pattern was generated by comparing modified voltage references with a carrier. The carrier was synchronized with the supply voltage using a PLL system, which made the control circuit complicated and costly. This paper discusses on the possibility of an asynchronized carrier. Experiment results show the input current distortion in case of asynchronous carrier is bigger than that of synchronous carrier. However, the deterioration can be minimized by increased carrier frequency.

• 전력전자학회논문지
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• 제17권2호
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• pp.129-134
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• 2012

In this paper, a new simple PWM method for Vienna rectifier is proposed. The previous SVPWM method for Vienna rectifier is very complex and difficult to implement. To solve these problems, a new single-carrier comparison PWM method for voltage control of Vienna rectifier is proposed. Because of using the only single carrier, implementation of the proposed PWM is very simple. In the proposed PWM method, carrier comparison parts of the PWM block is only changed from the 2 level PWM control block. The usefulness of the proposed PWM method is verified by the simulation and experiment.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1085-1091
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• 2014

This paper presents the guidance and control design for automatic carrier landing of a UAV (Unmanned Aerial Vehicle). Differently from automatic landing on a runway on the ground, the motion of a carrier deck is not fixed and affected by external factors such as ship movement and sea state. For this reason, robust guidance/control law is required for safe shipboard landing by taking the relative geometry between the UAV and the carrier deck into account. In this work, linear quadratic optimal controller and longitudinal/lateral trajectory tracking guidance algorithm are developed based on a linear UAV model. The feasibility of the proposed control scheme and guidance law for the carrier landing are verified via numerical simulations using X-Plane and Matlab/simulink.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1338-1341
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• 1997

In this paper, we propose angular rate computation algorithm using GPS carrier phase. A direct angylar rate masurement has not previously been available form GRS, although its availability is highly desirable for use in state feedback control. So we propose angular rate computationalgorithm which derive angular rate from the velocity of differentiated carrier phase og GPS. The proposed algorithm contains attitude determination using double-differentiated carrier phase and 2 baseline configuration whcih provide more practical applications than 3 baseline.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.302-305
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• 1995

An improved carrier PWM method for three phase voltage source inverters is proposed. The basic idea of the proposed method is deleting unnecessary 1/3 of switchings in the saw tooth carrier PWM method. The lowest frequency of the remained harmonics of this method (when the modulation index is large) is about 50% higher and the maximum modulated voltage is about 15% higher than those of the triangular carrier PWM method. This method will be useful especially in the linear feedback current control and MOSFET inverters.

• 대한기계학회논문집A
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• 제40권2호
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• pp.213-220
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• 2016

자기부상 수동형 이송 시스템이란 이송자에 부상, 안내, 추진과 관련된 전원장치가 없어 고청정, 무분진이 요구되는 환경에서 사용 가능한 시스템으로써 대면적 디스플레이 공정산업, 반도체 이송장비 등에 활용가능하다. 이 시스템은 이송 대상물의 안정적 운반을 위하여 이송자의 정밀한 자세 제어가 필요하다. 하지만 이송자의 구조적 특징 및 공극 센서 설치 오차에 의해 이송자의 피치운동이 발생하며 이를 해결하기 위한 제어기 설계가 필요하다. 본 논문에서는 자기부상 수동형 이송 시스템의 이송자 피치 운동을 감소시키는 제어에 목적이 있다. 이를 수행하기 위하여 해석적으로는 PDA 제어 모델과 피치제어를 추가한 제어 모델의 피치 각도를 비교한다. 실험적으로는 제어기 변경이 이송자의 피치 각도 및 부상 정밀도에 미치는 영향을 분석한다. 이러한 제어기 설계 변경이 피치 운동에 미치는 영향을 분석하고 부상 정밀도 향상을 위한 방법을 제시한다.

• International Journal of Control, Automation, and Systems
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• 제6권6호
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• pp.948-953
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• 2008

In high dynamic situations, the GPS carrier tracking loop requires a wide bandwidth to track a carrier signal because the Doppler frequency changes more rapidly with time. However, a wide bandwidth allows noises within the bandwidth of the tracking loop to pass through the loop filter. As these noises are used in the numerical controlled oscillator(NCO), the carrier tracking loop of a GPS receiver shows a degraded performance in high dynamic situations. To solve this problem, an adaptive two-stage Kalman filter, which offers the NCO a less noisy phase error, can be used. This filter is based on a carrier phase dynamic model and can adapt to an incomplete dynamic model and a quickly changed Doppler frequency. The performance of the proposed tracking loop is verified by several simulations.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.179-182
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• 1998

Carrier recovery, the process of recoverying the carrier in receiver, removes the phase difference between VCO and the received signal. However, the conventional structure of carrier recovery cannot be applied to multi-level QAM demodulator because of the increasing decision interval and the complexity of control as the number of symbol increases. In this paper, we suggest a new carrier recovery algorithm using $\theta-matching$ algorithm for multi-level QAM demodulation to overcome this problem and analysis the performance and implement it.

• 전력전자학회논문지
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• 제17권6호
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• pp.478-485
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• 2012

In this paper, a new PWM method is proposed to reduce the input current harmonics of 3 phase PWM rectifier. In the conventional carrier comparison PWM method, a triangular wave is generally used as the carrier wave. However, the large d-axis current ripple by the triangle carrier wave may be a source of large input current THD(Total Harmonic Distortion). In this paper, a new carrier comparison PWM method with saw tooth wave is proposed. Depending on the sector where the voltage command vector places, one of the rising or falling saw tooth wave is selected. To reduce the switching losses of the saw tooth carrier PWM, the discontinuous PWM is also presented. The proposed PWM method can reduce the d-axis current ripple as well as the switching losses. The performance of the conventional and proposed PWM methods is verified by the simulation and experimental results.