• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.5
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• pp.37-42
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• 2012

In this paper, a new charge pump is proposed to reduce the timing mismatch in the conventional current-steering charge pumps. Conventional current-steering charge pumps used NMOS input stages both for UP and DOWN signals, which resulted in different numbers of stage for UP and DOWN delay paths. The proposed charge pump has equalized the numbers of stages for UP and DOWN signals by using a PMOS stage for the DOWN signal. The simulation results show that the conventional current-steering charge pump has 14ns and 6ns for optimized timing mismatches between UP and DOWN signals for turn-on and turn-off, respectively. On the other hand, the proposed charge pump has improved timing mismatches of 6ns and 5ns for turn-on and turn-off, respectively. As a result, the reference spurs are reduced from -26dBc to -39dBc for the proposed charge pump. The proposed charge pump was designed by using $0.18{\mu}m$ CMOS technology. The measurement results show that the maximum variation of the charging and discharging current over the charge pump output voltage range of 0.3~1.5V is approximately 1.5%.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.29-34
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• 2010

This paper is aimed to develop monitoring software for detecting the characteristics of current and voltage signals for series arc on electric wire. In order to attain this purpose, the characteristics of series arc were analyzed by the current and voltage signals on electric wire which were installed, and also analyzed by the changes of RMS, instantaneous of waveform value in time domain and THD in frequency domain. Monitoring program which analyze the signal was developed by Labview which can analyze in time domain and frequency domain, and save data. Experimental setup for detecting verification of monitoring program was composed loads of a lamp, an electric heater and an electric fan loads which were usually using. Measurement points for detecting verification of monitoring program were selected at both the panel board and the arc generator at the same time. As results of the experiments by monitoring program, the arc current waveform showed the same characteristic in all measurement points of all load. But the arc voltage waveform was different in each measurement point. When arc occurred, the THD of current value increased above 20%. The results of this study will be effectively used in developing the preventive system of electric fire by series arc.

• Nuclear Engineering and Technology
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• v.36 no.6
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• pp.528-539
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• 2004

It is essential in commercial reactors that the safety limits imposed on the fuel pellets and fuel clad barriers, such as the linear power density (LPD) and the departure from nucleate boiling ratio (DNBR), are not violated during reactor operations. In order to accurately monitor the safety limits of current reactor states, a detailed three-dimensional (3D) core power distribution should be estimated from the in-core detector signals. In this paper, we propose a calculation methodology for detailed 3D core power distribution, using in-core detector signals and core monitoring constants such as the 3D Coupling Coefficients (3DCC), node power fraction, and pin-to-node factors. Also, the calculation method for several core safety parameters is introduced. The core monitoring constants for the real core state are promptly provided by the core design code and on-line MASTER (Multi-purpose Analyzer for Static and Transient Effects of Reactors), coupled with the core monitoring program. through the plant computer, core state variables, which include reactor thermal power, control rod bank position, boron concentration, inlet moderator temperature, and flow rate, are supplied as input data for MASTER. MASTER performs the core calculation based on the neutron balance equation and generates several core monitoring constants corresponding to the real core state in addition to the expected core power distribution. The accuracy of the developed method is verified through a comparison with the current CECOR method. Because in all the verification calculation cases the proposed method shows a more conservative value than the best estimated value and a less conservative one than the current CECOR and COLSS methods, it is also confirmed that this method secures a greater operating margin through the simulation of the YGN-3 Cycle-1 core from the viewpoint of the power peaking factor for the LPD and the pseudo hot pin axial power distribution for the DNBR calculation.

• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.2
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• pp.7-14
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• 1991

The integral model for the eddy current phenomena has been suggested. The model could lift the limitations of the previously well-known analytical model of eddy current theory. The model could be applied to two-dimentional, arbitary shaped defects. The computer programs have been developed in order to calculate the eddy current signal with the suggested integral method. The eddy current signals by the model calculations have been shown similar patterns to the actual experimental data from the real defects in the calibration standard tubes.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.443-446
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• 1991

In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the semiconductor reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is proposed in this paper and studied theoretically.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.222-229
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• 1999

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ration using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to cutting torque acting on a single tooth at the swept angle of cut and can be acquired form cutting torque signals. Average cutting torque per revolution can also be calculate form cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.57-64
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• 2000

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ratio using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to the cutting torque acting on a single tooth at the swept angle of cut and can be acquired from cutting torque signals. Average cutting torque per revolution can also be calculated from cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current. Varying immersion ratio is also estimated well using the presented algorithm.

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.240-244
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• 2010

In this work, we used PWM sampling for demodulation of a fiber-optic interferometric current transformer. The interference signal from a fiber-optic CT is sampled with PWM triggers that produce a 90-degree phase difference between two consecutively sampled signals. The current-induced phase is extracted by applying an arctangent demodulation and a phase unwrapping algorithm to the sampled signals. From experiments using the proposed demodulation, we obtained phase measurement accuracy and a linearity error, in AC current measurements, of ~2.35 mrad and 0.18%, respectively. The accuracy of the proposed method was compared with that of a lock-in amplifier demodulation, which showed only 0.36% difference. To compare the birefringence effects of different fiber-optic sensor coils, a flint glass fiber and a standard single-mode fiber were used under the same conditions. The flint glass fiber coil with a Faraday rotator mirror showed the best performance. Because of the simple hardware structure and signal processing, the proposed demodulation would be suitable for low-cost over-current monitoring in high voltage power systems.

• Proceedings of the Korean Magnestics Society Conference
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• 1997.11a
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• pp.124-125
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• 1997

• Journal of Power Electronics
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• v.19 no.3
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• pp.827-834
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• 2019

Wireless power transfer via coupled magnetic resonances has been a hot research topic in recent years. In addition, the number of related devices has also been increasing. However, reverse signals transfer is often required in addition to wireless power transfer. The structure of the circuit for a wireless power transfer system via coupled magnetic resonances is analyzed. The advantages and disadvantages of both parallel compensation and series compensation are listed. Then the compensation characteristics of the inductor, capacitor and resistor were studied and an appropriate compensation method was selected. The reverse signals can be transferred by controlling the compensation of the resistor. In addition, it can be demodulated by extracting the change of the primary current. A 3.3 MHz resonant frequency with a 100 kHz reverse signals transfer system platform was established in the laboratory. Experimental results demonstrate that wireless power and reverse signals can be transferred synchronously.