• 대한기계학회논문집A
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• 제26권1호
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• pp.15-22
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• 2002

This paper introduces a compensating system for machining error, which is resulted from chucking with separated jaws. In machining the chucked cylindrical workpiece, the deterioration of machining accuracy, such as out-of-roundness is inevitable due to the variation of the radial compliance of the chuck workpiece system which is caused by the position of jaws with respect to the direction of the applied force. To compensate the chucking compliance induced error, firstly roundness profile of workpiece due to chucking compliance after machining needs to be predicted. Then using this predicted profile, the compensated tool feed trajectory can be generated. And by synchronizing the cutting tool feed system with workpiece rotation, the chucking compliance induced error can be compensated. To satisfy the condition that the cutting tool feed system must provide high speed and high position accuracy, brushless linear DC motor is used. In this study, firstly through the force-deflection experiment in workpiece chucked lathe, the variation of radial compliance of chuck workpiece system is obtained. Secondly using the mathematical equation and cutting experiment result, the predicted profile of workpiece and its compensation tool trajectory are generated. Thirdly the configuration of compensation system using linear motor is introduced, and to improve the system performance, PID controller is designed. Finally the tracking performance of system is examined by experiment. Through the real cutting experiment, roundness is significantly improved.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권3호
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• pp.154-161
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• 2005

This paper proposes a speed-sensorless induction motor control system using a rotor speed compensation. To explain the proposed system, this paper describes an induction motor model in the synchronous reference frame for the vector control. The rotor flux is estimated by the rotor flux observer using the reduced-dimensional state estimator technique. The estimated rotor speed is directly obtained from the electrical frequency, the slip frequency, and the rotor speed compensation with the estimated q-axis rotor flux. The error of the rotor time constant is indirectly reflected in the rotor speed compensation using the compensation of the flux error angle. To precisely estimate the rotor flux, the actual value of the stator resistance, whose actual variation is reflected, is derived. An implementation of pulse-width modulation (PWM) pulses using an effective space vector modulation (SVM) is briefly mentioned. For fast calculation and improved performance of the proposed algorithm, all control functions are implemented in software using a digital signal processor (DSP) with its environmental circuits. Also, it is shown through experimental results that the proposed system gives good performance for the speed-sensorless induction motor control.

• International journal of advanced smart convergence
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• 제5권1호
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• pp.34-46
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• 2016

Networked Control System (NCS) has evolved in the past decade through the advances in communication technology. The problems involved in NCS are broadly classified into two categories namely network issues due to network and control performance due to system network. The network problems are related to bandwidth allocation, scheduling and network security, and the control problems deal with stability analysis and delay compensation. Various delays with variable length occur due to sharing a common network medium. Though most delays are very less and mostly neglected, the network induced delay is significant. It occurs when sensors, actuators, and controllers exchange data packet across the communication network. Networked induced delay arises from sensor to controller and controller to actuator. This paper presents an adaptive delay compensation process for efficient control. Though Smith predictor has been commonly used as dead time compensators, it is not adaptive to match with the stochastic behavior of network characteristics. Time delay adaptive compensation gives an effective control to solve dead time, and creates a virtual environment using the plant model and computed delay which is used to compensate the effect of delay. This approach is simulated using TrueTime simulator that is a Matlab Simulink based simulator facilitates co-simulation of controller task execution in real-time kernels, network transmissions and continuous plant dynamics for NCS. The simulation result is analyzed, and it is confirmed that this control provides good performance.

• 항공우주시스템공학회지
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• 제10권1호
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• pp.86-94
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• 2016

In this paper, position control of focal plane compensation device using piezoelectric actuator is conducted. The forcal plane compensation device installed on earth observation satellite camera compensates micro-vibration from reaction wheels. In this study, four experimental models of the open-loop compensation device are derived using MATLAB system identification toolbox in the input range of 0~50Hz. Subsequently, the PID controller for each model is designed and the performance test of each controller is conducted through MATLAB/Simulink. According to frequency response analysis of the closed-loop compensation device system, the PID controller designed for 38~50Hz input range has enough tracking performance for the whole 0~50Hz input range. The maximum output error is about $1{\mu}m$ for the input range. The simulation results has been verified by the experimental method.

• International Journal of Precision Engineering and Manufacturing
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• 제7권2호
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• pp.18-24
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• 2006

This paper proposes a LuGre Model-Based Neural Network (MBNN) friction compensation algorithm for a linear motor stage. For matching the friction phenomena in both the motion-start region and the motion-reverse region, the LuGre dynamic model is employed into the proposed compensation algorithm. After training of the model-based neural network is completed, the estimated friction for compensation is obtained. From the obtained result we find that the new structure gains advantage over the non-friction compensation system on the performance of the compensator in both regions. The proposed compensator is evaluated and compared experimentally with an uncompensated system on a microcomputer controlled linear motor tracking system in the final section of the paper. The experimental results show the improvement on the maximum velocity error and the root mean square tracking error in the motion-start region ranges from 34% to 53% and from 53% to 75% respectively, and in the motion-reverse region from 48% to 65% and from 79% to 90% respectively.

• 전력전자학회논문지
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• 제5권4호
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• pp.377-385
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• 2000

본 논문에서는 국내 최초로 설치된 Custom Power기기인 배전용 STATCOM(STATic COMpensator)의 기기 신뢰성 확보를 위힌 기가 테스트 및 설계통 운전 분석결과를 보이고 있다. Custom Power는 유연송전시스템(FACTS : Flexible AC Transmission System)과 같이 교류전력계통을 제어함으로써 효율적이고 유연한 전력계통의 운용과 구성을 목적으로 한다. STATCOM은 Custom Power기기의 한 형태로 무효전력 보상, 전압조정, 그리고 전압 퓰리커 억제 등의 기능을 가진다. 본 논문에서는 STATCOM 시운전 결과 무효전력과 역률 보상에서 우수한 성능을 보임을 확인할 수 있다.

• 산업경영시스템학회지
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• 제18권34호
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• pp.15-23
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• 1995

We study how to determine backorder cost at the warehouse in a one-warehouse/N-retailer distribution system such that channel efficiency (minimizing total system costs) is improved. We define backorder costs as compensation that the warehouse pays to the retailer for the number or orders delayed due to stockout at the warehouse. We answer two questions : (1) "Should the warehouse compensate for his backorder\ulcorner" and (2) "Is there any equilibrium for both the warehouse and retailer while they are seeking for their own profits\ulcorner" We show that : (1) "The warehouse should pay backorder costs for the sake of channel efficiency." and (2) "There exists an equilibrium that is infiuenced by the amount of compensation." First, we prove the existence of a mutually acceptable equilibrium for both the warehouse and the retailer, which is different from Nash equilibrium because they independently maximize their respective profits with incomplete information about each other. Second, we prove that the equilibrium moves to a point such that channel efficiency is improved if the warehouse compensates the retailers for his backorders. We show the existence of an optimal compensation that minimizes total system costs. Third, we show that the amount of optimal compensation increases as the ratio of mean lead time for the warehouse to that for the retailer increases.ouse to that for the retailer increases.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.769-780
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• 2018

This paper presents an analysis of the power gain under partial shading conditions (PSC) when the partial shade loss is being compensated in photovoltaic(PV) system. To analyze the power gain, our study divides the mismatch loss into partial shade loss and operating point loss. Partial shade loss is defined as the power difference between a normal string and a partially shaded string at the maximum power point (MPP). Operating point loss is defined as the power loss due to the operating point shift while following the MPP of the PV array. Partial shading in a PV system affects the maximum power point tracking (MPPT) control by creating multiple MPPs, which causes mismatch losses. Several MPPT algorithms have been suggested to solve the multiple MPP problems. Among these, mismatch compensation algorithms require additional power to compensate for the mismatch loss; however, these algorithms do not consider the gain or loss between the input power required for compensation and the increased output power obtained after compensation. This paper analyzes the power gain resulting from the partial shade loss compensation under PSC, using the V-P curve of the PV system, and verifies that power gain existence by simulation and experiment.

• 한국사회복지학
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• 제59권3호
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• pp.59-73
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• 2007

본 연구는 산재보험의 재해보상이 산재 여부에 따라 급여 수급을 전액받거나 혹은 전액 받지 못하는 체계로 인해 산재여부에 대한 판정의 복잡성과 갈등의 요소가 내재되어 있는 문제점의 개선에 초점을 두고 있다. 재해보상형태는 초기 원인주의에 입각한 사용자의 배상책임에 따라 배상 정도가 결정되었으나, 이후 무과실책임주의로의 전환과 재해인정범위의 확대 과정을 거치게 되었다. 이러한 발전은 재해인정에 있어서 All or Nothing 원칙 강화로 이어지게 된다. All or Nothing 원칙이 상당한 논란의 소지가 있음에도 부분인정제도를 도입하기 어려운 이유는 행정적 복잡성을 더욱 심화시키는 점에 있다. 따라서 선진국에서는 사회보장의 종합적 차원에서 보편적 보장을 통해 전체인정제도의 한계를 극복하고 있다. 하지만 한국의 경우 재해로 인한 비용발생이나 소득손실에 대해 종합적 보장체제가 이뤄져 있지 않아 산재인정과 관련된 논란이 심해질 우려가 있다. 따라서 보상차등화의 취지와 논리 수용을 통한 제도개선과 더불어 장기적으로는 종합적인 재해보상 체제 구축이 요구된다.

• 한국정밀공학회지
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• 제21권2호
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• pp.83-91
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• 2004

This paper illustrates the feasibility and the effectiveness of the disturbance feedforward compensation control proposed in the previous paper. The compensator is designed experimentally by means of the Multiple Filtered-x Least Mean Square algorithm. A 2-DOF active magnetic bearing system subject to base motion is built and the compensation control is applied. The experimental results demonstrate that the compensation control reduces the air-gap responses within 10$%$ of those by the feedback control alone without increasing the control inputs.