• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.267-269
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• 2007

PLL(Phase Locked Loop) are widely used circuit technique in modern electronic systems. In this paper, We propose the low voltage and high speed PLL. We design the PFD(Phase Frequency Detector) by using TSPC (True Single Phase Clock) circuit to improve the performance and solve the dead-zone problem. We use CP(Charge Pump} and LP(Loop filter) for Negative feedback and current reusing in order to solve current mismatch and switch mismatch problem. The VCO(Voltage controlled Oscillator) with 5-stage differential ring oscillator is used to exact output frequency. The divider is implemented by using D-type flip flops asynchronous dividing. The frequency divider has a constant division ratio 32. The frequency range of VCO has from 200MHz to 1.1GHz and have 1.7GHz/v of voltage gain. The proposed PLL is designed by using 0.18um CMOS processor with 1.8V supply voltage. Oscillator's input frequency is 25MHz, VCO output frequency is 800MHz and lock time is 5us. It is evaluated by using cadence spectra RF tools.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.875-876
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• 2006

Superconducting fault currents(SFCLs) are expected to improve not only reliability but also stability of power systems. The analysis on current limiting operations of the flux-lock type SFCL, which consists of a flux-lock reactor wound an iron core and a YBCO thin film, was compared the open-loop with the closed-loop iron core of the subtractive polarity winding. In the SFCL, operation characteristics could be controlled by adjusting the inductances and the winding directions of the coils, then magnetic field induced in the iron core. The current limiting characteristics under the same experimental conditions were generated regardless of the iron core conditions. We confirmed that capacity of the SFCL was increased effectively by the closed-loop iron core. However, the power burden of the system could be lowered by the open-loop iron core.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.178-183
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• 2006

Effect of coulomb friction and backlash on the single loop posit ion control has been studied for the precision position control. We studied and showed the limit cycle on the single loop system which used a ball screw that had the backlash. Also, We made an inner loop with a classical velocity and torque controller which was forcing the $i_d$ current to be zero by using a permanent-magnet synchronous motor and composed the outer loop with linear sensor for sensing a position of the loader. We have been shown a good result by using the dual loop through numerical simulation method.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.2
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• pp.59-61
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• 2006

In our country most of transmission lines are double-circuit lines. In these lines, the combining method of increasing conductor height and installation of passive shield-loop to mitigate magnetic field near a transmission line, is a good and feasible method. The basic principle of passive shield loop is that the field from the current induced in the shield loop conductors counteracts the field from the phase conductors. This method applied to domestic transmission lines to meet the magnetic field level, 100, 30, 10 and 4 mG, respectively. In each magnetic field level, the minimum conductor height and passive loop height are presented for the implementation of the practical design.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.74-76
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• 2017

In this paper, we introduce the CNN-based in-loop technology for HEVC, and analyze the performance of these algorithms through comparative experiments. The current in-loop filters in HEVC are composed of a deblocking filter that removes noise and a sample adaptive offset filter that compensates for signal offsets. A couple of CNN-based filters replacing the roles of these two algorithms are selected and compared.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1068-1070
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• 2000

This paper presents a method of designing the control loop for dc-to-dc converters when at characteristics of the converter's load are unknown. In the proposed method, a converter is considered as a stand-alone module that feeds a current sink load, and the control loop is designed in order to maximize the robustness of the converter's closed-loop performance. The proposed method yields a control design that provides predictable and controllable closed-loop performance for the converter loaded with an actual load.

• Smart Structures and Systems
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• v.23 no.6
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• pp.553-564
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• 2019

Modeling of magnetorheological (MR) dampers for cable vibration control to facilitate the design of even more effective and economical systems is still a challenging task. In this study, a parameter-adaptive three-element model is first established for a full-scale MR damper based on laboratory tests. The parameters of the model are represented by a set of empirical formulae in terms of displacement amplitude, voltage input, and excitation frequency. The model is then incorporated into the governing equation of cable-damper system for investigation of open-loop vibration control of stay cables in a cable-stayed bridge. The concept of optimal voltage/current input achieving the maximum damping for the system is put forward and verified. Multi-mode suboptimal and Single-mode optimal open-loop control method is then developed. Important conclusions are drawn on application issues and unique characteristics of open-loop cable vibration control using MR dampers.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.6
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• pp.33-37
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• 1974

In this paper, the radiation characteristics for the array of a circular loop antenna is studied in moving media. The medium is assumed to be homogeneous, isotropic, and to move with a constant velocity much less than the speed of light. The integral equation for the current distribution is derived and the current functions is found by means of courier Series as a solution of the integral equation. The electric field is derived from the current on circular loop antenna and the Dyadic Green's Function in moving media. The numerical calculation of the electric field concerning to the two element antenna array,, in which one element is parasitic, is carried out. The field patterns are plotted from the computed values. As a result, the field patterns in moving media, compared with the patterns in stationary media, are found to decrease in the direction of media velocity and increase in the opposite direction, and the maximum directivity is shifted.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.1
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• pp.7-12
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• 2006

This paper proposes the new voltage event detection method using the weight factor of neural network and describes control system design for the DVR(Dynamic Voltage Restorer) consisted of a rectifier and series inverter applied to 22.9kV distribution system. As this method can express the fault level of each phase, we expect the proposed method can make up for disadvantage of synchronous detection method. Also, in this paper, the control system was designed using double deadbeat controller, As it has an inner current control loop and an outer voltage control loop, we can easily limit the current level during the transient intervals by using the current control loop. Simulation and experiment are performed to prove the analysis of the voltage event detection method and double deadbeat controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.2
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• pp.262-268
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• 2019

Previous dynamic models of hysteresis motor use an extended induction machine equivalent circuit or somewhat different equivalent circuit with conventional one, which makes unsatisfiable results. In this paper, the hysteresis dynamic characteristics of the motor rotor are analyzed using the inverse Preisach model and the hysteresis motor equivalent circuit considering eddy current effect. The hysteresis loop for the rotor ring is analyzed under full-load voltage source static state. The calculated hysteresis loop is then approximated to an ellipse for simplicity of dynamic computation. The permeability and delay angle of the elliptic loop apply to the dynamic analysis model. As a result, it is possible to dynamically analyze the hysteresis motor according to the applied voltage and the rotor material. With this method, the motor speed, generated torque, load angle, rotor current as well as synchronous entry time, hunting effect can be calculated.