• 한국산학기술학회논문지
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• 제18권11호
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• pp.718-724
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• 2017

최근 생산 부분에 집중되어 있던 국내 해양플랜트 산업구조를 엔지니어링 분야로 확대하기 위한 노력이 지속되어왔다. 하지만 부유식 해양플랜트 엔지니어링 기술의 핵심 중 하나인 시간대역에서의 운동해석의 경우 국외 회사에서 제공되는 정보에 거의 전적으로 의존하여 왔다. 특히 동적 위치 유지 시스템은 초기 설계에서 해외 선진사가 제공하는 정보에 기반하며, 그 결과를 선형에 반영하기 위해서는 시간적으로나 비용 면에서 많은 손실을 감수해야 한다. 본 논문에서는 동적위치유지시스템 (Dynamic Positioning System, DPS)을 사용하는 부유식 해양구조물의 시간대역 운동 해석에 필요한 프로그램의 프레임워크를 다룬다. 개발된 프레임워크는 시간대역 해석을 쉽게 수행할 수 있도록 해석에 필요한 입력 데이터를 생성하고, DPS의 제어 알고리즘 및 성능을 평가할 수 있도록 모듈화 하였다. 이를 통해 DPS의 배치 및 용량결정과 여러 가지 제어 알고리즘의 테스트가 쉽게 이루어지도록 하였다. 실제 모델 선박을 이용한 시뮬레이션을 통해 개발된 프레임워크의 실효성을 검증하였으며 전체 작업에 걸리는 시간이 50% 이상 감소하는 것을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.125-129
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• 1987

The stability margin of the LQ regulator is investigated in the time domain. it is shown that the same guaranteed gain margin as that of the frequency domain analysis can be obtained with simple assumptions for the continuous time systems. It is also shown that the allowable modelling error bound can be expressed in terms of system matrices and Riccati equation solution. Guaranteed qain. margin and the allowable modelling error bound for the discrete time systems are also obtained by the similar procedures. In this case, through the some examples, the gain margin is shown to be less conservative than the frequency domain analysis result.

• 대한조선학회지
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• 제21권3호
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• pp.35-42
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• 1984

In this paper, the lateral motions of a ship in the time domain are treated by applying the Impulse Response Function Technique. The acceleration, and displacement of a ship in the time domain are needed for the purpose of such automatic controls as the fire control system and the auto-pilot of ocean-going vessels, etc. The response Amplitude Operators of a ship are calculated by the Strip Method of Salvesen-Tuck-Faltinsen, and the Pierson-Moskowitz Spectrum multiplied by spreading function is used to represent the short crested ocean waves. The ocean wave elevations in the time domain are simulated according to the Method of Borgman. Finally the rudder effect is considered by simply adding the force and moment due to the rudder to the wave exciting force. And the results of lateral motions with and without rudder are shown.

• 제어로봇시스템학회논문지
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• 제11권4호
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• pp.378-384
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• 2005

This paper proposes a theoretically rigorous analysis procedure that compares the position domain and range domain carrier-smoothed-code filters for differential GNSS positioning. Utilizing consistent error covariance formulation, it is shown that filtering in the position domain is, in theory, more advantageous than range domain carrier-smoothed-code filtering. It is also shown that if the visible satellite set does not change during a sufficiently long time interval the performances of position and range domain filters are similar.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.27-33
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• 1997

In this paper, instantaneous controller of a single-phase PWM converter is realized using DSP. The stable PI gain of the input current and the DC link voltage control system is designed. The DC link voltage control system can be designed in continuous-time domain. But as for the input current control system, the descretizing effect cannot be ignored so it must be designed in descrete-time domain considering the calculation time. The capacitance estimating algorithm which can be acquired through the ripple voltage is proposed. By this algorithm the DC link capacitance can be estimated even under the transient state. Experimental results show the input power factor of 99.1% and the voltage variation rate of $\pm$5% according to the load variation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.91-94
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• 2003

In this paper, we achieve implementation of a Time-Frequency Domain Reflectometry(TFDR) system through comparatively low performance(100MS/s) PCI extensions for Instrumentation(PXI). The TFDR is the general methodology of Time Domain Reflectometry(TDR) and Frequency Domain Reflectometry(FDR). This methodology is robust in Gaussian noises, because the fixed frequency bandwidth is used. Moreover, the methodology can get more information of the fault by using the normalized time-frequency cross correlation function. The Arbitrary Waveform Generator(AWG) module generates the input signal, and the digital oscilloscope module acquires the input and reflected signals, while PXI controller module performs the control of the total PXI modules and execution of the main algorithm. The maximum range of measurement and the blind spot are calculated according ta variations of time duration and frequency bandwidth. On the basis of above calculations, the algorithm and the design of input signals used in the TFDR system are verified by real experiments. The correlation function is added to the TDR methodology for reduction of the blind spot in the TFDR system.

• 전력전자학회논문지
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• 제3권4호
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• pp.338-345
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• 1998

The mathematical interpretation of a practical sampler which is useful to obtain the small signal models for the peak and average current mode controls is proposed. Due to the difficulties in applying the Shannons sampling theorem to the analysis of sampling effects embedded in the current mode control, several different approaches have been reported. However, these approaches require the information of the inductor current in a discrete expression, which restricts the application of the reported method only to the peak current mode control. In this paper, the mathematical expressions of sampling effects on a current loop which can directly apply the Shannons sampling theorem are newly proposed, and applied to the modeling of the peak current mode control. By the newly derived models of a practial smapler, the models in a discrete time domain and a continuous time domain are obtained. It is expected that the derived models are useful for the control loop design of power supplies. The effectiveness of the derived models are verified through the simulation and experimental results.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.1-7
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• 2007

In this paper, the necessary and sufficient conditions for strict positive realness of the rational transfer functions directly from basic definitions in the frequency domain are studied. A new frequency domain approach is used to check if a rational transfer function is a strictly positive real or not. This approach is based on the Taylor expansion and the Maximum Modulus Principle which are the fundamental tools in the complex functions analysis. Four related common statements in the strict positive realness literature which is appeared in the control theory are discussed. The drawback of these common statements is analyzed through some counter examples. Moreover a new necessary condition for strict positive realness is obtained from high frequency behavior of the Nyquist diagram of the transfer function. Finally a more simplified and completed conditions for strict positive realness of single-input single-output linear time-invariant systems are presented based on the complex functions analysis approach.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.380-382
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• 1989

It is necessary for us to maintain good the quality of products in iron and steel making process, especially in the rolling mill plants. Thus, we need check the stability criteria of control systems. In the frequency domain, the whole system including controllers can be identified using FFT analyzer. But this method is not adequete where precise identification is demanded. Thus a way to complement the defects In the frequency domain analysis using FFT analyzer is introduced. And In the time domain, to establish the stability criteria on the control systems, the assumed parameters obtained using least square method are presented in this report.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.275-278
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• 1998

The mathematical interpretation of a practical sampler which is useful to obtain the small signal models for the peak and average current mode controls is proposed. Due to the difficulties in applying the Shannon's sampling theorem to the analysis of sampling effects embedded in the current mode control, several different approaches have been reported. However, these approaches require the information of the inductor current in a discrete expression, which restricts the application of the reported method only to the peak current mode control. In this paper, the mathematical expressions of sampling effects on a current loop which can directly apply the Shannon's sampling theorem are newly proposed, and applied to the modeling of the peak current mode control. By the newly derived models of a practical sampler, the models in a discrete time domain and a continuous time domain are obtained. It is expected that the derived models are useful for the control loop design of power supplies. The effectiveness of the derived models are verified through the simulation and experimental results.