• International Journal of Control, Automation, and Systems
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• 제4권4호
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• pp.506-515
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• 2006

This paper studies an intelligent digital control for nonlinear systems with multirate sampling. It is worth noting that the multirate control design is addressed for a given nonlinear system represented by Takagi-Sugeno (T-S) fuzzy models. The main features of the proposed method are that i) it is provided that the sufficient conditions for stabilization of the discrete-time T-S fuzzy system in the sense of Lyapunov stability criterion, which is can be formulated in the linear matrix inequalities (LMIs); and ii) the stability properties of the trivial solution of the digital control system can be deduced from that of the solution of its discretized versions. An example is provided for showing the feasibility of the proposed method.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.469-473
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• 2005

Capacities of a tandom-type air-conditioner may be modulated by turning on/off multiple compressors and adjusting positions of a electronic expansion valve. In this study. control algorithms for compressors and a electronic expansion valve were developed by using fuzzy’ logics. There algorithms were implemented in a test lab and proved to be effective for the control of indoor air temperature and superheat temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.57-60
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• 2001

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• 한국지능시스템학회:학술대회논문집
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• 한국지능시스템학회 2008년도 춘계학술대회 학술발표회 논문집
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• pp.233-236
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• 2008

Recently, the development and application of unmaned robots are increasing in various fields including surveillance and reconnaissance, planet exploration and disaster relief. Unmaned robots are usually controlled from distance using radio communications but they should be equipped with autonomous travelling function to cope with unexpected terrains and obstacles. This means that unmanned robots should be able to evaluate terrain's characteristics quantitatively using mounted sensors so as to traverse harsh natural terrains autonomously. For this purpose, this paper presents an algorithm for extracting terrain information from elevation maps as an early step of traversability analysis. Slope and roughness information are extracted from a world terrain map based on least squares method and fractal theory, respectively. The effectiveness of the proposed algorithm is verified on both fractal and real terrain maps.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1271-1272
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• 2007

Experimental results regarding to the structural properties of carbon nanotubes (CNTs) and the field-emission characteristics of CNT-coated tungsten (W) tips are presented. CNTs are successfully grown on conical-type W-tips by inductively coupled plasma-chemical vapor deposition (ICP-CVD) with or without inserting a TiN-buffer layer prior to the formation of Ni catalysts. For all the CNTs grown, their nanostructures, morphologies, and crystalline structures are analyzed by FESEM, HRTEM, and Raman spectroscopy. Furthermore, the emission properties of CNT-based field-emitters are characterized to estimate the maximum current density and the threshold voltage. The results obtained in this study indicate that the emission current level of the CNT-emitter without using a TiN buffer is desirable for the application of micro-focused x-ray systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.255-258
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• 1996

This paper describes a DC voltage controller for the DC power supply which is constructed using the full-bridged MOS-FET DC-to-RF power inverter and rectifier. The full-bridged MOS-FET DC-to-RF inverter consisting of four MOSFET arrays and an output power transformer has a control function which is able to control the RF output power when the widths of the pulse voltages which are fed to four MOS-FET arrays of the fall-bridged inverter are changed using the pulse width control circuit. The power conversion efficiency of the full-bridged MOS-FET DC-to-RF power inverter was approximately 85 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The RF output voltage from the full-bridged MOS-FET DC-to-RF inverter is fed to the rectifier circuit through the output transformer. The rectifier circuit consists of GaAs schottky diodes and filters, each of which is made of a coil and capacitors. The power conversion efficiency of the rectifier circuit was over 80 % when the duty cycles of the pulse voltages were changed from 30 % to 50 %. The output voltage of the rectifier circuit was changed from 34.7V to 37.6 V when the duty cycles of the pulse voltages were changed from 30 % to 50 %.

• 한국컴퓨터정보학회논문지
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• 제20권5호
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• pp.113-121
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• 2015

이 연구는 국내 시스템경비업체의 보안관리 개선을 위한 경영대책의 일환으로 관제시설에 대한 구축 프로세스와 보안관리 방안을 제안한다. 관제시설은 시스템경비의 중추신경으로 현장의 대응체제가 아무리 잘 구축되어 있더라도 관제시설이 장애나 재해로 작동이 중단되거나 관제기계경비원이 위해를 입게 되면 본래의 기능을 수행할 수 없기 때문이다. 관제시설의 구축 프로세스는 공간구조, 기반시설, 관제장치, 관제 솔루션, 운영조직으로 구분하고, 보안관리 방안으로는 물리보안, 정보보안, 인적보안에 대한 대책을 제시한다.

• 제어로봇시스템학회논문지
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• 제21권10호
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• pp.903-909
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• 2015

This article presents an integrated chassis control with electronic stability control (ESC) and active front steering (AFS) under saturation of front lateral tire force. Regardless of the use of AFS, the front lateral tire forces can be easily saturated. Under the saturated front lateral tire force, AFS cannot be effective to generate a control yaw moment needed for the integrated chassis control. In this paper, new integrated chassis control is proposed in order to limit the use of AFS in case the front lateral tire force is saturated. Weighed pseudo-inverse control allocation (WPCA) with variable weight is adopted to adaptively use the AFS. To check the effectiveness of the proposed scheme, simulation is performed on a vehicle simulation package, CarSim. From simulation, the proposed integrated chassis control is effective for vehicle stability control under saturated front lateral tire force.

• 한국산학기술학회논문지
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• 제13권6호
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• pp.2428-2434
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• 2012

본 논문은 제동 시스템에서 전자식 주행안정 제어장치(ESC)의 유압 모듈레이터의 솔레노이드 밸브 제어에 대한 것이다. ESC의 전자제어유니트(ECU)를 제어하기 위한 방법으로 고주파수 제어와 슬로프 제어를 적용하였으며, 서지 압력 및 전자파간섭(EMI) 저감 특성을 연구하였다. 고주파수에서의 전자파 방출을 줄이기 위하여 ECU 출력 단에 슬로프 제어 기능을 추가하였다. 측정결과 제동 시스템에서 고주파수 ECU의 솔레노이드 밸브제어 방법에 따라 서지 압력과 전자파 방출이 저감될 수 있음을 확인하였다. 결론적으로 고주파수 ECU 제어 연구 결과에 의해 제동 시스템 성능을 향상방안을 제시하고자 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.1069-1074
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• 1989

A discrete-time learning control for robotic manipulators is studied using its pulse transfer function. Firstly, discrete-time learning stability condition which is applicable to single-input two-outputs systems is derived. Secondly, stability of learning algorithm with position signal is studied. In this case, when sampling period is small, the algorithm is not stable because of an unstable zero of the system. Thirdly, stability of algorithm with position and velocity signals is studied. In this case, we can stabilize the learning control system which is unstable in learning with only position signal. Finally, simulation results on the trajectory control of robotic manipulators using the discrete-time learning control are shown. This simulation results agree well with the analytical ones.