• Proceedings of the KSME Conference
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• 2000.11a
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• pp.564-569
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• 2000

Model Based Compensator(MBC) is recently used for the analysis of multi-variable control in frequency domain. Target loop is designed by the demanding requirements such as cross-over frequency, disturbance rejection in low frequency domain, zero steady-state error, identification of maximum and minimum singular values and sensor noise rejection in high frequency domain. Loop transfer recovery will be continued in frequency domain until the plant with MBC comes close to the target loop. In this study, the technique using MBC is applied to the elevator vibration control system. It is found that this technique is very effective to control the vibration system.

• Journal of Magnetics
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• v.22 no.1
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• pp.150-154
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• 2017

A novel high precision spatial positioning method utilizing the electromagnetic momentum, i.e., Electromagnetic Momentum Positioning (EMP), is proposed in this paper. By measuring the momentum of the electromagnetic field around the small current loop, the relative position between the sensor and the current loop is calculated. This method is particularly suitable for the application of close-range and high-precision positioning, e.g., data gloves and medical devices in personal healthcare, etc. The simulation results show that EMP method can give a high accuracy with the positioning error less than 1 mm, which is better than the traditional magnetic positioning devices with the error greater than 1 cm. This method lays the foundation for the application of data gloves to meet the accurate positioning requirement, such as the high precision interaction in Virtual Reality (VR), Augmented Reality (AR) and personal wearable devices network.

• Journal of Power Electronics
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• v.10 no.5
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• pp.518-527
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• 2010

This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.2
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• pp.115-127
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• 2020

In this paper, a sustainable close-loop supply chain (SCLSC) model is proposed for effectively managing the production, distribution and handling process of mobile phone. The proposed SCLSC model aims at maximizing total profit as economic factor, minimizing total CO₂ emission amount as environmental factor, and maximizing social influence as social factor in order to reinforce sustainability in it. Since these three factors are represented as each objective function in modeling, the proposed SCLSC model can be taken into consideration as a multi-objective optimization problem and solved using a hybrid genetic algorithm (HGA) approach. In numerical experiment, three different scales of the SCLSC model are presented and the efficiency of the HGA approach is proved using various measures of performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.397-403
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• 2016

Generally, an electrical distribution configuration is a radial system with one-way current in a distribution management system (DMS). All feeders in a DMS have tie-switches to make radial system. Sometimes, DMS should change a tie-switch for operation. In that case, the tie-switch has to be closed first; then a switch is opened as another tie-switch in order to prevent blackout for customers. At the moment when the tie-switch is closed, distribution system is operated in a loop state, not radial. Before the loop operation, DMS operator has to check any expected events for stable distribution system operation; and the most important event is a mis-operation of a protection relay. In addition, DMS operator should check voltage profile violation but a calculation method of section voltages had not been used. Thus, this paper proposes a calculation method of section voltages at a loop operation in a DMS. The proposed calculation algorithm is verified by Matlap Simulink.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2907-2912
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• 2007

The cooling water system for the PEFP 20 MeV proton accelerator was established and tested to obtain the precise resonance frequency of DTL through the temperature control of cooling water. The water temperature in the main flow loop was manipulated by adjusting the proportion of hot water returning from the DTL structures through the heat exchanger loop. Due to low duty factor operation and insufficient cooling loop installation of the DTL tanks, the manual mode operation was applied to maintain the DTL temperatures close to their resonance temperatures. The optimized process conditions with flow balancing and pressure drop in the DTL cooling systems are reported.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.49-54
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• 2012

There is a possibility that electrical sparks may occur at discontinuities in metallic structures from distance of close to high power radio/radar transmitters. Voltage may be induced on these metallic structures by the radio-frequency transmitter. In this case, a person who comes into contact with these structure may be undergone a severe electrical shock. In this paper, assessment of the electrical shock and ignition hazards was investigated through experimental which are consisted radio transmitter and metallic loop-type structure in shield room. We measured that the induced voltage was highest at 61 MHz of transmission frequency, and confirmed the possibility of electric shock and explosion induced by a voltage or spark. But it is needed additional research where is opened site.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.16-19
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• 1994

This paper describes a design method of compensators for decentralized control systems. Decentralized control problem is convenient to design multi-variable control systems and formulated as a series of independent designs. The proposed design method is composed of some steps, which is sequentially to close loop of the system diagonalized by regarding interactive subsystem as perturbation for current loop. So, on the basis of H$_{\infty}$ control theory, decentralized controllers are designed considering robust stability for diagonal systems with perturbations. A numerical example shows that the proposed design method is effective for multivariable control systems..

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.4
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• pp.534-542
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• 2017

This paper presents a fast locking technique for a fractional-N PLL frequency synthesizer. The technique directly measures $K_{VCO}$ on a chip, computes the VCO's target tuning voltage for a given target frequency, and directly sets the loop filter voltage to the target voltage before the PLL begins the normal closed-loop locking process. The closed-loop lock time is significantly minimized because the initial frequency of the VCO are put very close to the desired final target value. The proposed technique is realized and designed for a 4.3-5.3 GHz fractional-N synthesizer in 65 nm CMOS and successfully verified through extensive simulations. The lock time is less than $12.8{\mu}s$ over the entire tuning range. Simulation verifications demonstrate that the proposed method is very effective in reducing the synthesizer lock time.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.956-960
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• 2004

The Vehicle Dynamic Simulator(VDS) is a key equipment of the performance verification of attitude control subsystem and it simulates the real dynamic environment that spacecraft undergoes during mission operation. All the software models and hardware interfaces necessary for the closed-loop simulation of the spacecraft dynamics are implemented. Using VDS, KOMPAT-2 attitude control logic functions and performance was verified. In this paper, the hardware and software configurations of KOMPSAT-2 VDS was described briefly and the information flow and exchanges between software models and actual hardwares during close loop simulation was described in the systematic point of view.