• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.59-60
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• 2015

본 논문에서는 직류송전 적용을 위해 전력계통과 연계된 모듈형 멀터레벨 컨버터(Modular Multi-level Converter)의 유 무효 전력제어에 대해 시뮬레이션 모델을 개발하고 그 특성을 분석하였다. 분석에 고려한 모듈형 멀티레벨 컨버터는 한 암당 12개의 서브모듈로 구성되어 있고 모듈레이션은 NLC (Nearest Level Control) 방식을 사용한다. 또한 DC 커패시터의 밸런싱은 버블소팅 방식을 적용하였고 순환전류를 억제하는 알고리즘을 고려하였다. 시뮬레이션을 통해 분석한 유 무효전류제어를 실험적으로 검증하기 위해 10kVA DC 1000V 하드웨어 축소모형을 제작하고 실험을 실시하였다. 실험결과는 시뮬레이션 결과와 일치함을 확인할 수 있었다. 향후에는 교류전압 불평형 보상과 순환전류 제어, 컨버터 보호에 대한 다양한 알고리즘을 도출할 예정이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1633-1637
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• 2008

A protocol is proposed to control the rate of each subcarrier in OFDM-based wireless network systems. The proposed protocol adds an OFDM symbol in CTS frame defined in IEEE 802.11 standard. A receiver determines the rate of its subcarrier after it receives the RTS frame. The determined rate is added to OFDM symbol in CTS frame. In order to synchronize the rate information between the sender and the receiver, error recovery process is proposed. The performance improvement of the proposed method is shown by numerical results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.88-94
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• 2004

The KSR-III rocket is a liquid propellant sounding rocket and thrust vector control actuators and cold gas thrusters are used to control pitch and yaw, roll attitude respectively during thrusting phase. In this paper, the structure of designed attitude controller and gain scheduling, results of stability analysis for KSR-III rocket are presented. The attitude controller is implemented with flight software in the domestically developed INS and successfully performed its function in the flight test. The flight data are coincident with simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.15-21
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• 2000

This paper presents the modeling method of $3\Phi$ phase-controlled rectifier for the DC motor drive in MATLAB/SIMULINK environment. This method has no need to extend the system mathematically and thus it's easy to integrate the various systems. The whole model consists of $3\Phi$ phase-controlled rectifier block, DC motor block and speed/current controller block. The simulation results show that the model outputs are almost similar to those of the real system and therefore that the presented method is suitable for the research of the closed-loop controlled power electronic systems.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1225-1230
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• 2014

This paper investigates the group average-consensus and group formation-consensus problems for first-order multi-agent systems. The control protocol for group consensus is designed by considering the positive adjacency elements. Since each intra-group Laplacian matrix cannot be satisfied with the in-degree balance because of the positive adjacency elements between groups, we decompose the Laplacian matrix into an intra-group Laplacian matrix and an inter-group Laplacian matrix. Moreover, average matrices are used in the control protocol to analyze the stability of multi-agent systems with a fixed and undirected communication topology. Using the graph theory and the Lyapunov functional, stability analysis is performed for group average-consensus and group formation-consensus, respectively. Finally, some simulation results are presented to validate the effectiveness of the proposed control protocol for group consensus.

• Journal of the Korean Geotechnical Society
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• v.17 no.1
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• pp.15-24
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• 2001

흙필터는 일반적으로 침식이나 파이핑으로부터 지반 구조물을 보호하기 위하여 사용된다. 세립자들이 유동하여 필터에 퇴적하는 폐색현상이 발생하는 경우, 간극수압이 증가하고 이로 인해 지반구조물의 불안정을 유발시키게 된다. 미세입자의 유동에 의한 폐색현상은 옹벽의 뒤채움재에 설치한 필터, 흙댐의 저부에 설치된 필터, 그리고 터널의 라이닝 뒤에 설치한 필터 등에서 발생할 수 있다. 폐색현상은 필터의 투수능을 저하시켜 배수능력에 상당한 위험을 초래할 수 있다. 본 연구에서는 필터의 폐색으로 인한 투수능 저하 정도를 실험을 통해 관찰하고 이론적인 모델을 통해 정량화 시키고자 하였다. 일정한 농도의 현탁액이 필터로 유입되는 분리형 실험과 현장상태를 모사하는 흙-필터 시스템의 결합형 실험을 통해 투수능의 저하현상이 압력 제어조건과 유량 제어조건에서 관찰되었고, 서로 비교 분석되었다. 미세입자가 통과하는 필터의 간극을 모세관으로 가정한 후 모세관에서 유체의 흐름 원리를 이용하여 물리적인 폐색에 의해 발생하는 투수능 저하현상을 이론적인 모델로 구성하였다. 일반적으로 투수능은 1/10 수준으로 감소되었으며, 분리형 실험에 의한 결과와 이론적인 모델의 결과는 잘 일치하였다. 또한, 결합형 실험결과와 분리형 실험결과가 비교적 잘 일치하여 투수능 저하예측은 분리형 실험이나 이론적 모델에 의하여 가능하리라 판단되었다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.139-147
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• 2014

We address the problem of corrective control for two asynchronous sequential machines in parallel connection. Each asynchronous machine receives the same external input and shows independent state transition characteristics. We propose a novel control scheme in which only one corrective controller is employed so as to make the closed-loop system of each machine match the behavior of the corresponding reference model. Compared with the former method utilizing two corrective controllers, our scheme can reduce the controller size and computational load in controller design. We present the existence condition and design procedure for a state-feedback corrective controller under the assumption that the controlled machines are of input/state type. The design procedure for the proposed controller is described in an illustrative example.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.161-169
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• 2004

This paper deals with system identification of a three-story building model with active mass damper (MID) for the controller design. Observer Kalman filter identification (OKID) technique is applied to find the relationship between the experimental results of the input and output. The inputs to the building model with MID are ground accelerations and motor command signal, which are, respectively, simulated earthquake and equivalent control force. The outputs are each floor acceleration and MID acceleration. The MID controller is designed based on the experimentally identified building system. Finally it is shown that experimental results agree accurately with simulated results.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.1-10
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• 2008

The problem of controlling asynchronous sequential machines is addressed in this paper. Corrective control means to make behavior of an asynchronous sequential machine equal to that of a given model. The main objective is to develope a corrective controller, especially when a model is given as nondeterministic, or a set of reference models. The structure of corrective control system for asynchronous sequential machines is addressed first, followed by description of nondeterministic models. Then, we propose a method for analyzing reachability of asynchronous machines and nondeterministic models. Proposed methods are demonstrated in an example.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.476-482
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• 2010

In this paper, we propose a robust path tracking control method for autonomous underwater vehicle with variable speed. The proposed path tracking controller consists of a kinematic controller and a dynamic controller. First, the kinematic controller computes the surge speed and yaw rate to follow the reference path with variable speed. Then the dynamic controller controls the thrust force and yaw torque to move the AUV actually. In the dynamic control, we assume that the sway speed is a disturbance. In addition the dynamic controller is designed based on sliding mode conrol. We also demonstrate the stability of the proposed control method by Lyapunov stability theory. Finally, simulation results illustrate the performance of the proposed control method.