• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.10-14
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• 2013

High precision machining technology has become one of the important parts in the development of a precision machine. Such a machine requires high precision positioning as well as high speed on a large workspace. For machining systems having a high precision positioning with a long stroke, it is necessary to examine the repeatability of reference position decision. Though ball-screw driven linear stages equipped linear scale have high precision feed drivers and a long stroke, they have some limitations for reference position decision if they have not equipped the accurate home sensor. This study is performed to experimentally examine the repeatability for home position decision of a magnetic sensor as a home switch of ball-screw driven linear stage by using capacitance probe.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.145-146
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• 2011

In this paper, a bridgeless flyback power factor correction (PFC) rectifier which uses single magnetic core is proposed. The proposed PFC rectifiers utilize bidirectional switch to handle both positive and negative input voltage without bridge diodes. A transformer with dual output windings enables the rectifier dispense with any additional magnetic component. The operation of the proposed flyback PFC rectifier is analyzed, and its higher efficiency than its conventional counterpart is verified by experiment.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.306-311
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• 2005

In this paper, the electromagnetic force acting in the arc column of 3 different extinction units is compared with using the FEM (Finite Element Method) and the arc velocity is calculated by the drag force of the fluid mechanics. The experiment for breaking the arc current was performed in each model at 100 volts in order to measure the arcing time. The outcome was compared with the computing value. As a result, this paper proposes that the divided U-shaped grid is able to shorten arcing time and improve the electric performance. It also suggests a methodology for comparing and analyzing the result obtained by simulation and experiment.

• 전기학회논문지
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• 제58권8호
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• pp.1532-1537
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• 2009

Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2100-2101
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• 2008

This paper is studied on a protective control system for electrical fire and electrical faults due to over current or electric short circuit faults by using electrical thermal characteristics of PTC (Positive Temperature Coefficient) thermistor and current response characteristics of high sensitive reed switch. The PTC thermistor has characteristic of positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with BaTiO3_Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point, and reed switch, which is used for electrical fault current sensing devices, have a excellent characteristic of response velocity in degree of ${\mu}s{\sim}ms$ that sensing magnetic flux in proportion to dimension of line current. This paper is proposed on a protective control system use PTC thermistor and reed switch for sensor which is protected from electrical fire due to overload faults or electric short circuit faults. Some experimental results of the proposed electric safety control device are confirmed to the validity of the analytical results.

• 대한전기학회논문지
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• 제33권11호
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• pp.456-463
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• 1984

The fast-rising high-voltage pulse generation circuit system of a theta pinch is both theoretically and experimentally investigated. The idealized model of this circuit system is a hybrid circuit system composed of three parts: a lumped circuit part being consisted of a capacitor bank and a spark switch connected in series, another lumped circuit part being consisted of the Blumlein transmission line, whose end load is the pinch coil. the voltage difference between two ends of the pinch coil is formulated by analyzing this hybrid circuit system by means of the law of the signal propagation in the transmission line and Kirchhoff's laws. The expedient numerical method for computer calculation is developed to generate the pulse profile of the voltage difference across the pinch coil. The period of the experimentally measured main pulse is a fourth of the theoretical one neglecting the resistance of the pinch coil. We attribute this discrepancy to the modelling in the theoretical calculation that hte resistance and inductance of the spark switch and capacitor bank are assumed to be constant through discharge. Therefore, we can see that the rise time of the imploding magnetic-field pulse is mainly dependent on the spark switch and capacitor bank.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권8호
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• pp.452-461
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• 2003

The reliability and accuracy of the information on control rod position are very important to the reactor safety and the design of the core protection system. A survey on the RSPT(Reed Switch Position Transmitter) type control rod position indicator system and its actual implementation in the existing nuclear power plants in Korea was performed first. The control rod position indicator having the high performance for SMART was developed on the basis of RSPT technology identified through the survey. The arrangement of permanent magnet and reed switches is the most important procedure in the design of control rod position indicator. The hysteresis of reed switches is one of the important factors in a repeat accuracy of control rod position indicator as well. This paper investigates efficiency of the magnetic flux concentrator and the hysteresis using FEM and verified differences in physicals characteristics by comparing the results of FEM and those of the experiment. As a result, it is shown that the characteristics of prototype control rod position indicator have a good agreement with the results of FEM.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.3114-3120
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• 2014

산업현장에서 사용되는 무선 비상호출 스위치의 성공적인 운영을 위해서는 지속적인 전원의 공급이 이루어져야 한다. 본 논문은 배터리가 필요 없는 무선 스위치에 적용할 수 있는 전자기 유도방식의 초소형 에너지 하베스팅 메커니즘 개발 및 구현된 메커니즘의 성능 실험 결과를 보여주고 있다. 연구결과로 단 방향 누름 동작과 2mm 이동거리의 제한조건 내에서, 유도기전력을 생성하는 새로운 메커니즘이 제시됐다. 또한, 구현된 메커니즘의 전자기 유도 발전 출력 성능 실험결과로 VDC $4.5V{\pm}25%$(도달시간 1.2msec), 2.5V 이상 전압의 발전시간이 65ms가 됨을 보여주고 있다.

• Journal of Power Electronics
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• 제19권1호
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• pp.11-23
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• 2019

In this study, a novel zero voltage zero current transition (ZVZCT) bidirectional DC-DC converter is proposed by employing coupled inductors. This converter can turn the main switch on at ZVZCT and it can turn it off with zero voltage switching (ZVS) for both the boost and buck modes. These characteristics are obtained by using a simple auxiliary sub-circuit regardless of the power flow direction. In the boost mode, the auxiliary switch achieves zero current switching (ZCS) turn-on and ZVS turn off. Due to the coupling inductors, this converter can make further efficiency improvements because the resonant energy in the capacitor or inductor can be transferred to the load. The main diode operates with ZVT turn-on and ZCS turn-off in the boost mode. For the buck mode, there is a releasing circuit to conduct the currents generated by the magnetic flux leakage to the output. The auxiliary switch turns on with ZCS and it turns off with ZVT. The main diode also turns on with ZVT and turns off with ZCS. The design method and operation principles of the converter are discussed. A 500 W experimental prototype has been built and verified by experimental results.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.318-321
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• 2002

Superconductivity has various applications in the whole industry such as the generation of high magnetic field for medical care and diagnosis, the lossless power transmission, environment-friendly vehicles and clean energy storage systems. This paper deals with the High-Tc superconducting(HTS) power supply using heater-triggered switch for the charging of the superconducting magnets. HTS superconducting power supply consists of two heaters, an electromagnet, and Bi-2223 solenoid and Bi-2223 pancake is used as a superconducting load, similar to real HTS magnet. The timing sequential control of two heaters and an electromagnet is an important factor to generate pumping- current in the Bi-2223 load. The thermal analysis of switching parts of the Bi-2223 solenoid according to the heater input was carried out. Based upon the analysis, the 0.8A of heater current were optimally derived. The maximum pumping current reached 1.7A.