• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2578-2580
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• 1999

In this paper, an embedded micro processor based resistance spot welding controller is introduced which has been recently developed by Hyosung Co. Ltd. The performance of rapid and constant high current control is tested experimentally. This paper shows configurations of measuring system for high current and realtime RMS conversion techniques of sampled discrete data. A digital proportional control is adopted for this system and the result shows that this new product is working well at wide range of welding current and the performance is improved compared with some other commercially available controllers that are widely used in our industries. User friendly MMI system and a computer network system to monitor each welding processes are also presented.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2562-2567
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• 2005

This paper suggests a new method discretization of nonlinear system using Taylor series expansion and zero-order hold assumption. This method is applied into the sampled-data representation of a nonlinear system with input time delay. Additionally, the delayed input is time varying and its amplitude is bounded. The maximum time-delayed input is assumed to be two sampling periods. Them mathematical expressions of the discretization method are presented and the ability of the algorithm is tested for some of the examples. And 'hybrid' discretization scheme that result from a combination of the ‘scaling and squaring' technique with the Taylor method are also proposed, especially under condition of very low sampling rates. The computer simulation proves the proposed algorithm discretized the nonlinear system with the variable time-delayed input accurately.

• 산업경영시스템학회지
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• 제10권16호
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• pp.39-51
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• 1987

This paper deals with the case analysis of second order processes under sampled-data. Proportional Integral-Derivative(PID) control, and development of Decision Support Systems(DSS) for such processes. In this paper three techniques were described for identifying the dynamics of closed loop stable processes. The first, called pulse testing is a frequency-domain method, which yields the frequency response diagram of an open loop process. The second is a time-domain method which yields the gain and time constants of the process model. The third technique is based on step response and gives the parameters of PID controllers. The development of DSS design programs consisting of above three techniques will provide very powerful tools in the microcomputer based process control.

• 한국정밀공학회지
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• 제12권11호
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• pp.82-90
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• 1995

This paper pressents a condition-based maintenance (CBM) method through bibration analysis. The well known frequency analysis is employed for performing machine fault diagnosis. The statistical control chart is also applied for analyzing the trend of the bearing wear. Vibration sensors are attached to prototype machine and signals are continuously monitored. The sampled data are utilized to evaluate how well the fast fourier transform(FFT) and the statistical control chart techniques could be used to identify defects of machine and to analyze the machine degradation. Experimental results show that the propowed approach could classify every mal-function and could be utilized for real machine diagnosis system.

• 수산해양교육연구
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• 제19권1호
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• pp.74-83
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• 2007

These days business logistics has become one of the very important factors of logistics cost reduction and customer service satisfaction. In order to control business logistics more effectively, many companies must be concerned about logistics performance.This study aims at analyzing information system characteristic and logistics performance. The information system characteristic variables are considered IS resource, IS strategic role. The logistics performance variables are considered logistic cost, customer service.For data on the 301 sampled company, a mail survey using a questionnaire was conducted in this study. The following results were obtained.First, IS characteristic variables were significant for logistics performance. Specially, efficient management of IS manpower and IS planning, present IS were significant for logistics performance. Second, there also were IS manpower and IS planning, present IS that indentifing high logistics performance group and low logistics performance group.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2765-2770
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• 2003

This paper introduces a novel control algorithm, energy bounding algorithm, for stable haptic interaction. The energy bounding algorithm restricts energy generated by zero-order hold within consumable energy by physical damping that is energy consumption element in the haptic interface. The passivity condition can always be guaranteed by the energy bounding algorithm. The virtual coupling algorithm restricts the actuator force with respect to the penetration depth and restricts generated energy. In contrast, energy bounding algorithm restricts the change of actuator force with respect to time and restricts generated energy by zero-order hold. Therefore, much stiffer contact simulation can be implemented by the energy bounding algorithm. Moreover, the energy bounding algorithm doesn’t is not computationally intensive and the implementation of it is very simple.

• 대한전자공학회논문지
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• 제27권2호
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• pp.1-8
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• 1990

부호율 r=b/n인 2진길쌈부호의 부등 비트오류 제어특성을 해석한다. Viterbi 복호되어 나온 b비트로 구성된 정보벡터에서 각 비트가 갖는 오류확률은 서로 다를 수 있다. 따라서 각 비트의 오류제어 성능은 그외 다른 비트의 오류제어 성능과 다를 수 있다. 이러한 부등 비트 오류특성은 DPCM 시스템의 표본 데이타를 전송할 때 전송상에서 신호대 잡음비의 개선을 위해 적용될 수 있다.

• 한국정보통신학회논문지
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• 제6권1호
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• pp.1-5
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• 2002

디지털 제어시스템을 설계하려면, 먼저 아날로그 시스템을 설계한 후, 이산화하여 디지털 시스템을 설계한다. 본 논문에서는 최적 디지털 제어기의 선계에 샘플치 제어이론을 적용한다. 특히, 아날로그 제어기들의 멀티레이트 이산화에 Η$_2$최적화를 이용한다. 멀티레이트 구조상 인과성 제약을 갖는 멀티레이트 Η$_2$최적화를 통해 해를 얻는다. 설계 예제를 통해, 기존 이산화 방법과 비교하여, 멀티레이트 설계방법의 우수성을 확인한다.

• 지구물리와물리탐사
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• 제14권1호
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• pp.1-6
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• 2011

상업적인 주파수영역 항공전자탐사 장비의 개별적인 하부시스템의 계기변화와 보정에 대한 점검방법으로 유인성 제약조건만을 사용하여 광대역 이상성분 자료로부터 통상성분을 예측하고자 한다. 이상성분 자료로부터 통상성분의 반응을 예측하는 방법은 다음을 포함한 몇 가지가 있다: (1) 기준면 변화, 보정, 위상의 점검에 대한 품질관리; (2) 이상생분 측정으로부터 통상성분의 잡음수준 예측 및 확인 그리고 향후에는 그 반대과정도 가능할 것이다; (3) 주파수영역과 시간영역의 더 나은 변환과 유인성을 충족시키기 위해 성기게 측정된 자료의 내삽 및 외삽 실제로 수치모형자료와 Resolve 헬리곱터에 탑재된 전자기 탐사 장비로 측정된 주파수 영역 자료에 대한 실험 결과, 통상성분 자료들은 비율을 맞춘 힐버트 변환에 의해서 40에서 80 ppm의 표준편차를 갖고 예측될 수 있다는 것을 알았다. 그러나, 비행간의 기준면들 사이의 상대적인 차이는 1 ppm보다 더 정확히 분석될 수 있으며 이는 계기변화 보정의 정밀도에 대해 독립적인 품질관리를 가능하게 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1-6
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• 1993

This report proposes a novel method of identification of continuous time-delay systems from sampled input-output data. By the aid of a digital pre-filter, an approximated discrete-time estimation model is first derived, in which the system parameters remain in their original form and the time delay need not be an integral multiple of th sampling period. Then an identification method combining the common linear least squares(LS) method or the instrumental variable(IV) method with the genetic algorithm(GA) is proposed. That is, the time-delay is selected by the GA, and the system parameters are estimated by the LS or IV method. Furthermore, the proposed method is extended to the case of multi-input multi-output systems where the time-delays in the individual input channels may differ each other. Simulation resutls show that our method yields consistent estimates even in the presence of high measurement noises.