• 조명전기설비학회논문지
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• 제28권2호
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• pp.60-69
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• 2014

This paper proposed the circulation current control scheme in the single phase inverter system. The load experiment of the power conversion system including the UPS usually uses the passive components such as resistors and inductors. Therefore, the energy consumption is serious problem. In addition, the system is out of order when it is installed in the local area, and the load experiment can not perform adequately after troubleshooting, because there is no the load equipment, and the power capacity is not enough in the local area. The paper does the research on the circulation current control scheme, it does not need the load equipment, and the load current can reuse as the input current of the equipment. Instead of the conventional method the voltage-voltage and voltage-current control scheme introduced the parallel converter concept is newly proposed, and the validity of the proposed control scheme is investigated by both simulation and experimental results.

• 한국수소및신에너지학회논문집
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• 제22권6호
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• pp.835-841
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• 2011

The humidification is essential for performance enhancement of the electrolysis of PEMFC because proton conductivity depends on hydration of the proton exchange membrane. In this study, the humidification experiment did about On/Off control the humidification and dew condensation for PEMFC by using of the membrane humidifiers. As the results, it was possible to approximation control of the humidity by using of the solenoid valve On/Off control on the membrane humidifier. Also the problem on the dew condensation was resolved by approximation humidity control through solenoid valve On/Off control and the removal of the dew condensation in the flow channel was verified through visualization experiment.

• 한국정밀공학회지
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• 제14권11호
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• pp.34-41
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• 1997

This paper presents a technique to control a very flexible robot moving in a vertical plane. The flexible robot is modeled as an Euler-Bernoulli beam. Elastic deformation is approximated using the assmed modes method. A comparison function which satisfies all geometric and natural boundary conditions of a cantilever beam with an end mass is used as an assumed mode shape. Lagrange's equation is utilized for the development of a discretized model. A control algorithm is developed using a simple PID cnotrol tech- nique. The proportional, integral and deivative control gains are determined based on the dominant pole placement method and tuned to show no overshoot and no steady state error, and short settling time. The effectiveness of the developed control scheme is showed in the hub angular diaplacement control experiment. Three different end masses are uned in the experiment. The experimental results show that developed control algorithm is very effective showing little overshoot, no steady state error, and less than 2.5 second settl- ing time in case of having an end mass which is equivalent to 45% of the manipulator mass. Also the experimental results show that the residual vibration fo the end point is effectively controlled.

• 한국환경복원기술학회지
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• 제7권3호
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• pp.56-63
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• 2004

This study was carried out to find out the effect of by-product gypsum(phosphogypsum, PG) application on enhancement of turf quality. For the first experiment, 10 ton $ha^{-1}$ PG was applied to 1m${\times}$10m (width${\times}$length) Plots with 4 replicates on a sloping area of fairway where turf(Zoysia japonica L.) was grown. Both top- and sub-soil samples were collected before and after treatment and were analyzed for pH, EC(e1ectrica1 conductivity), Ca and Mg contents. At the same time when soil samples were collected, specific color difference sensor value(SCDSV) that represented chlorophyll contents, fresh and dry weight of the turf were determined to find out the effect of PG treatment on turf growth. SCDSV of turf from PG treated plots measured at 98 and 147 days after treatment were significantly higher than those from control. Considering higher fresh and dry weight of leaf per unit area from PG treated plots than that from control, it was concluded that the elevated Ca and S level of the PG treated plots resulted in vigorous leaf growth of turf. For the second experiment 2, 5 and 10 ton $ha^{-1}$ PG were applied to 1m${\times}$10m(width${\times}$length) Plots with 3 replicates at a closer location as was used for the first experiment to find out the appropriate PG application rate. Before and after treatment soil and plant samples were collected and were analyzed by the same way as the first experiment. The pH of all the soil samples collected from PG treated plots at 38 days after treatment was lower than that from control. This trend changed as time passed. However, the pH of the soil from 10 ton $ha^{-1}$ PG treated plot was lower than that from control during the whole period of the second experiment. SCDSV, fresh and dry weight of leaf from PG treated plots at all 3 rates were higher than those from control for the second experiment. PG application to turf will be beneficial for both mass consumption of by-product gypsum and enhancement of turf quality.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
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• pp.1-12
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• 2001

In cold forging of piston-pin for automobile parts, the flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The purpose of this study is to investigate the material flow behavior of forward-backward extruded piston-pin through the relative velocity ratio and the stroke control of upper moving punch & container using the flow control forming technique. The finite element simulations are applied to analyse the flow defect, then the results are compared with the plasticine model material experiments. Finally, the model experiment results are in good agreement with the FE simulation ones.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1888-1893
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• 1991

Systematic design of a controller for a water temperature system was considered, with the intention of devising an accurate control experiment. The results of an experiment using a water temperature system based on the pole placement regulator showed water temperature oscillation and steady state error. This paper proposed a. method for eliminating both the oscillation and the steady state error. The oscillation was eliminated by a drive delay compensation technique, in which a future state value of the system was predicted through a real time computer simulation. The steady state error was eliminated by an steady state error correction technique, in which an actual steady state heatrate in the system model was replaced by an imaginary heatrate. By combining these two techniques, we obtained an experimental result for water temperature control of 0.01 (.deg. C) accuracy. Furthermore, the proposed method was evaluated relatively by comparing the experimental results using several other methods and proved to be the most accurate and convenient control method for the delay system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.731-736
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• 2001

In this thesis, the study on controlling of cracks of concrete box culvert in early ages is presented. The optimum construction method and economical analysis were proposed also through the experiment of the material and field test. As a result of the experiment of the material, using fly ash, CSA expansive agent and BELITE cement(type IV) showed good result in the control of cracks induced by heat of hydration and shrinkage. As a result of construction test analysis, the maintenance time of form system did not show a big difference in controlling of cracks. Control of distribution of reinforcement, spacing of expansion joint and use of BELITE cement showed big differences in the control of cracks in early ages. As a result of economical analysis, control of construction variables before construction can make it possible to reduce the repair expense.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1944-1947
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• 2005

In this paper, the control of a prosthetic arm using the flex sensor signal is described. The flex sensors are attached to the biceps and triceps brchii muscle. The signals are passed a differential amplifier and noise filter. And then the signals are converted to digital data by PCI 6036E ADC. From the data, position and velocity of arm joint are obtained. Also motion of the forearm - flexion and extension, the pronation and supination are abstracted from the data by proposed algorithm. A two D.O.F arm with RC servo-motor is designed for experiment. The arm length is 200 mm, weight is 4.5 N. The rotation angle of elbow joint is $120^{\circ}$. Also the rotation angle of the wrist is $180^{\circ}$. Through the experiment, we verified the possibility of the prosthetic arm control using the flex sensor signal. We will try to improve the control accuracy of the prosthetic arm continuously.

• 한국군사과학기술학회지
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• 제7권4호
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• pp.107-113
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• 2004

In order to model a connection part between a control fin and actuator, the related characteristics of a dynamic stiffness were extracted from experiments. These characteristics include the static stiffness of a control fin and the dynamic stiffness of an actuator, so they are called the mixed dynamic stiffness here. This mixed dynamic stiffness is used as the boundary condition of a control fin connected to an actuator when the flutter characteristics are analyzed. The simulated stiffness of an actuator is corrected from the experiment results and the mixed dynamic is finally formulated in the domain of frequencies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.110-112
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• 2003

Electric control of eddy coupling offers many new possibilities in process control and other industrial control applications. And a form of speed control for the load is affected for a system driven by costant frequency induction motor. This paper analysis speed-torque characteristic of the eddy-current coupling by using the 3-dimensional analytical method. Characteristic experiment is put into operation for the claw pole type eddy current coupling. Design procedure is presented based on the analysis.