• 전기학회논문지
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• 제66권1호
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• pp.72-81
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• 2017

We propose a switching control scheme for the control of a ball and beam system. It was reported in [4] that a ball and beam system is a nonlinear system which has an ill-defined relative degree. So, the traditional control approaches have been mostly either Jacobian-based control or approximate input-output linearized control in nature. In this paper, motivated by [7], we combine these two traditional control approaches and operate each controller via a pre-designed switching logic so that the improved control result can be obtained without any excessive use of control input. Switching algorithm is developed based on both analysis and actual experimental observation. We verify the effectiveness of our proposed controller via actual experimental results.

• 한국자동차공학회논문집
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• 제21권6호
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• pp.209-217
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• 2013

This paper presents a control strategy of 4 wheel drive (4WD) vehicles. Proposed control strategy has simple structure and can easily apply to various vehicles with low cost and time. It is consist of feedforward control for traction ability, fedback control for minimizing the wheel speed difference and yaw control for lateral stability. In addition, to integrate the traction and stability control, a blending function is applied. To evaluate the feasibility of the proposed control strategy, actual vehicle experiment is conducted after deciding the tuning parameter through the simulation. The simulation is accomplished by CarSim and Matlab/Simulink and the actual vehicle test is conducted using full size Sports Utility Vehicle (SUV) equipped rear wheel based solenoid type 4WD device.

• 전력전자학회논문지
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• 제22권3호
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• pp.223-230
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• 2017

A low-cost BLDC motor with hall sensor is used to drive the position control of a facility security monitoring system in this paper. Low measurable frequency of the hall sensor signal in low-speed regions results in difficulty in obtaining accurate speed detection and position control. To improve system control performance, we propose a variable gain of position controller and stop mode control scheme according to the motor speed and error position with pre-set deceleration time. The proposed stop mode control scheme is activated around the stop position to forcibly move the BLDC motor to the stop position in low speed. In the proposed stop mode, the motor current is controlled by the actual speed with the reference rotating angle. The control performance of the proposed position control is verified through experiments at the actual rail guided facility security monitoring system.

• 설비공학논문집
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• 제27권3호
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• pp.137-145
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• 2015

In this study, the actual energy consumption of the secondary side of District Heating System (DHS) with different hot water supply temperature control methods are compared. Three methods are Set-point Control, Outdoor Temperature Reset Control and Outdoor Temperature Prediction Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side of the system, the results show that Outdoor Temperature Prediction Control method saves more energy. In general, Outdoor Temperature Prediction Control method lowers the supply temperature of hot water, and it reduces standby losses and increases overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, Outdoor Temperature Prediction Control method saves about 7.1% in comparison to Outdoor Temperature Reset Control method and about 15.7% in comparison to Set-point Control method. Also, it is found that at when partial load condition, such as daytime, the fluctuation of hot water supply temperature with Set-point Control is more severe than Outdoor Temperature Prediction Control. Therefore, it proves that Outdoor Temperature Prediction Control is more stable even at the partial load conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.660-663
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• 1997

In recent manufacturing process, the increase of productivity is required by reducing machining time with the increase of cutting force. However, the excessive increase of cutting force can cause tool breakage, and have a bad effect on both the manufacturing machine and the workpiece. Thus, it is necessary to estimate and control cutting force in real time during the process. In this study, use of disturbance observer is proposed for the indirect cutting force estimation. The estimated cutting force is used for the real time control of feedrate, making the actual cutting force follow the reference force command. Since the suggested method does not need an expensive sensor like a dynamometer, the method is expected to be used practically. By reducing the machining time resulting from making the actual cutting force follow the reference force, the increase of productivity are also expected, and the quality of cutting surface has been improved due to the adjusted feedrate. Besides, an actual constant cutting force guarantees the prevention of tool breakage. To show the effectiveness of the suggested cutting force control method, an experimental setup has been made without the force sensor, applied to several workpieces. Experiments show that the suggested method is superior to the conventional method operated by constant feedrate.

• 전기학회논문지
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• 제61권3호
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• pp.442-450
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• 2012

Almost domestic power plants are being operated by foreign distributed control system. Many korean power plants are being operated over their lifetime so they need to be retrofitted. So we are developing the distributed control system to solve this problem by our own technique. The simulator was already made to verify the reliability of the algorithms. The unit loop function tests of all algorithms were finished in the actual distributed control system for installation of power plant and their results were satisfactory. The unit loop function tests are for each unit equipment algorithm. So the total operation tests will be made with all algorithms together in the actual distributed control system to be applied to power plant. When the verification through all tests is finished, algorithms with hardware will be scheduled to be installed and operated in the actual power plant. This research result will contribute to the safe operation of the deteriorated power plant and korean electric power supply as well as domestic technical progress. This entire processes and results for the development are written for the example of boiler feedwater master algorithm out of all algorithms in this paper.

• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.36-42
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• 2019

The ESP (Electronic Stability Program) is an active control system that controls the posture of the vehicle by sensing the unstable state of the vehicle during braking, driving, or turning. The system works if the vehicle becomes unstable and it is very dangerous to develop it in the actual vehicle. For this reason, many studies have been carried out on the method of developing with simulation such as SIL / EIL. Some advanced companies have already applied it to the product development process. In this study, ESP hydraulic system and braking device model were constructed using SimulationX to build ESP SIL / EIL model. The hydraulic system model was constructed using the actual design parameters and the performance of the hydraulic model was verified by comparing with the actual vehicle test.

• 드라이브 ㆍ 컨트롤
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• 제14권2호
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• pp.16-22
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• 2017

This paper presents the algorithm of an adaptive model-free-control-based steering control for multi-axle all-terrain cranes for which the recursive least squares with forgetting are applied. To optimally control the actual system in the real world, the linear or nonlinear mathematical model of the system should be given for the determination of the optimal control inputs; however, it is difficult to derive the mathematical model due to the actual system's complexity and nonlinearity. To address this problem, the proposed adaptive model-free controller is used to control the steering angle of a multi-axle crane. The proposed model-free control algorithm uses only the input and output signals of the system to determine the optimal inputs. The recursive least-squares algorithm identifies first-order systems. The uncertainty between the identified system and the actual system was estimated based on the disturbance observer. The proposed control algorithm was used for the steering control of a multi-axle crane, where only the steering input and the desired yaw rate were employed, to track the reference path. The controller and performance evaluations were constructed and conducted in the Matlab/Simulink environment. The evaluation results show that the proposed adaptive model-free-control-based steering-control algorithm produces a sound path-tracking performance.

• 대한간호학회지
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• 제18권2호
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• pp.118-127
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• 1988

This descriptive-correlational study was undertaken in order to examine if there was relationship between health locus of control and health behavior of 122 residents in Choong Nam Province. The sampling method was non-probability, conventent sampling technique. Questionnaire survey was conducted from March 2 to March 11, 1988. Each participant completed the Multidimensional Health Locus of control(MHLC) scale (Wallsten & Wallston, 1978) and Health Behavior scale (developed by Dr. cho) The collected data were analyzed using Peason Correlation coefficient, t-test and Analusis of Variance. The results were as follows : 1. Hypothesis 1, stating that the higer the score of internal health locus of control, the higher the Score of level of actual implementation of health behavior was supported(r＝.1344, p＜.05). 2. Hypothesis 2, stating that the higher the score of chance health locus of control, the lower the score of level of actual implementation of health behavior was not supported (r＝-.1344, p＞.05). 3. Hypothesis 3, stating that the higher the score of internal health locus of control, the higher the score of the level of perceived importance of health behavior was supported (r＝.3373, p＜.001). 4. Hypothesis 4, stating that the higher the score of chance health locus of control, the lower the score of level of perceived importance of health behavior was not supported (r＝-.0810, p＞.05). 5. The mean score of internal was 23.36, powerful others was 19.04 and chance 15.36 out of maximum range of 6-30 respectively. The mean score of level of actual implementation of health behavior was 112.84 and level of perceived importance of health behavior 143.60 our of maximum range of 32-160 respectively. 6. The variances which were related with the level of actual implementation of health behavior, were education level, occupation, economic status, referred method of primary health, management and resicent's place. And the variance which were related with the level of perceived importance of health behavior were sex, economic status and occupation.

• 한국조경학회지
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• 제36권1호
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• pp.38-48
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• 2008

This study examines the characteristics of the herbaceous vegetation structure of Haneul Park District in World Cup Park, which had previously been used as a landfill for 15 years. The survey was carried out through actual vegetation and vegetation structures from 2003 to 2006, biannually. Firstly, as a result of analysis of actual vegetation, the autumn season changed more quickly over the 2 year span than did the spring season in terms of actual vegetation area. Annual plants increased for the initial $3{\sim}4$ years and then perennial plants increased. Secondly, the results of analysis in vegetation structure are as follows: 1. The number of planted species gradually decreased. 2. Miscanthus sinensis var. purpurascens of the control region was maintained but Imperata cylindrica var. koenigii of the non-control region was invaded by Miscanthus sacchariflorus, Glycine soja and Phragmites communis etc. 3. Planted species in the control region were maintained in superior state, but the non-control region was changed by natural occurrence plants until 2006, the fourth year. 4. Physostegia virginiana and Aster koraiensis which were planted in the non-control region were maintained but most of planted species weakened and changed by natural occurrence plants including Erigeron annuus, Artemisia princeps, Setaria faberii and Phragmites communis etc. Based on the results, we suggested the management method of herbaceous vegetation in the Haneul Park District.