• 한국지능시스템학회논문지
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• 제6권2호
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• pp.111-119
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• 1996

In this paper, we propose time-optimal trajectory planning algorithms for cooperative multi-robot manipulators system considering optimal load distribution. Internal forces essentially effect on time optimal trajectory planning and if they are comitted, the time optimal scheme is not no longer true. Therefore, we try to find the internal force factors of cooperative robot manipulators system in a time-optimal aspect. In this approach, a specific generalized inverse is used and is fuzzified for the purpose. In this optimal method, the fuzzy logic concept is used and selected for diminishing computation time, for finding the load distribution factors.

• Journal of Power Electronics
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• 제12권5호
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• pp.769-777
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• 2012

In this paper, a new development in the time optimal control theory in sliding mode control systems for multi-quadrant buck converters with a variable load is presented. In general, the closed-loop time optimal control system is applied to multi-quadrant buck converters for output regulation, so that an optimal switching surface is obtained. Moreover, an adjusted optimal sliding mode controller is suggested which adjusts the controller parameters to give an optimal switching surface. In addition, a description of the transient response of the closed-loop system is proposed and used to damp any output or input disturbances in minimum time. Numerical simulations and experimental results are employed to demonstrate that the output regulation time and transient performances of dc/dc converters using the proposed technique are improved effectively when compared to the classical sliding mode control method.

• 산업기술연구
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• 제21권B호
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• pp.85-89
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• 2001

In this paper, we analyze a time-based update method in location management and calculate the optimal time-interval. The probability that an MT is j rings away from the center cell is obtained by computer programming. And using these values, an exact analysis is made for the time-based location management cost. From the result, when the time-based method is applied to location update, we can get the optimal time-interval which minimizes the location management cost.

• 전기의세계
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• 제26권2호
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• pp.84-88
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• 1977

In this paper we apply the maximum principle to design of time optimal nonlinear sampled-data control systems. We introduce the general design procedures and the mathematical formalas for time optimal processes and trajectories. Then we show the application of the technique to determine the optimal control signal, control sequence, switching time and sampling period to the given 4th order process.

• 한국컴퓨터산업학회논문지
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• 제2권9호
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• pp.1155-1162
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• 2001

본 논문은 UNIX 시스템의 최적 이용률(Optimal Utilization)을 결정하는 방법을 제시한다. 제시된 방법은 사용자가 인내할 수 있는 응답시간(Tolerable Response Time)을 제공하는 범위에서 사용자에게 허용될 수 있는 최대 이용률이 최적 이용률이 된다는 정의(Definition)를 근거로 하여 개발되었다. 인내할 수 있는 응답시간이 길어지면 최적 이용률도 높아지므로 최적 이용률은 인내할 수 있는 응답시간의 최대값에서 구해진다. 인내할 수 있는 응답시간은 서비스 목표(Service Objective)가 주어지면 도출해 낼 수 있다. 본 논문에서는 인내할 수 있는 응답시간이 0.24초라는 것과 최적 이용률의 세 가지 구성요소는 %wio, %sys, %usr 이라는 것을 보여준다. 또한 최적 이용률을 결정하는 실제의 과정을 예시하기 위하여 UNIX 운영체제를 사용하는 IBM 컴퓨터의 최적 이용률을 구하는 과정을 예시한다.

• 품질경영학회지
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• 제48권1호
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• pp.201-214
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• 2020

Purpose: The purpose of this paper is to determine an optimal number of cycle times for the replacement under the circumstance where the system is replaced at the periodic time and the multiple number of working cycles whichever occurs first and the system is minimally repaired between the replacements if it fails. Methods: The system is replaced at periodic time () or cycle time, whichever occurs first, and is repaired minimally when it fails between successive replacements. To determine the optimal number of cycle times, the expected total cost rate is optimized with respect to the number of cycle times, where the expected total cost rate is defined as the ratio of the expected total cost between replacements to the expected time between replacements. Results: In this paper, we conduct a sensitivity analysis to find the following results. First, when the expected number of failures per unit time increases, the optimal number of cycle times decreases. Second, when the periodic time for replacement becomes longer, the optimal number of cycle times decreases. Third, when the expected value for exponential distribution of the cycle time increases, the optimal number of cycle times increases. Conclusion: A mathematical model is suggested to find the optimal number of cycle times and numerical examples are provided through the sensitivity analysis on the model parameters to see the patterns for changes of the optimal number of cycle times.

• 품질경영학회지
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• 제47권1호
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• pp.87-96
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• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• 한국정밀공학회지
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• 제18권10호
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• pp.116-126
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• 2001

This paper suggests a numerical method to find optimal geometric path and minimum-time motion for a spatial 6-link manipulator arm (PUMA 560 type). To find a minimum-time motion, the optimal geometric paths minimizing 2 different dynamic performance indices are searched first, and the minimum-time motions are searched on these optimal paths. In the algorithm to find optimal geometric paths, the objective functions (performance indices) are selected to minimize joint velocities, actuator forces or the combinations of them as well as to avoid one static obstacle. In the minimum-time algorithm the traveling time is expressed by the power series including 21 terms. The coefficients of the series are obtained using nonlinear programming to minimize the total traveling time subject to the constraints of velocity-dependent actuator forces.

• 한국정보처리학회논문지
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• 제2권5호
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• pp.807-813
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• 1995

본 논문은 UNIX 시스템의 최적 이용율(Optimal Utilization)을 결정하는 방법을 제시한다. 제시된 방법은 사용자가 인내할 수 있는 응답시간(Tolerable Response Time) 을 제공하는 범위에서 사용자에게 허용될 수 있는 최대 이용율이 최적 이용율이 된다 는 정의(Definition)를 근거로하여 개발되었다. 인내할 수 있는 응답시간이 길어지면 최적 이용율도 높아지므로 최적 이용율은 인내할 수 있는 응답시간의 최대값에서 구해 진다. 인내할 수 있는 응답시간은 서비스 목표(Service Objective) 가 주어지면 도출 해낼 수 있다. 본 논문에서는 인내할 수 있는 응답시간이 0.24초라는 것과 최적 이용 율의 세가지 구성요소는 %wio, %sys, %usr이라는 것을 보여준다. 또한 최적 이용율을 결정하는 실제의 과정을 예시하기 위하여 UNIX 운영체제를 사용하는 IBM 3081 컴퓨터 의 최적 이용율을 구하는 과정을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.293-298
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• 1993

In this paper, methods for computing the time-optimal motion of a robotic manipulator are presented that considers the nonlinear manipulator dynamics, actuator constraints, joint limits, and obstacles. The optimization problem can be reduced to a search for the time-optimal path in the n-dimensional position space. These paths are further optimized with a local path optimization to yield a global optimal solution. Time-optimal motion of a robot with an articulated arm is presented as an example.