• 한국정보통신학회논문지
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• 제11권12호
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• pp.2343-2351
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• 2007

본 논문은 시변 펄스형 자기장(Time-varying Magnetic field)을 반복적으로 발생시키는 전원장치 및 전원장치에서 발생된 에너지를 자기장으로 발생키시기 위한 자기유도 코일 probe의 설계 및 구현을 통하여 짧은 시간($300{\mu}s$이하) 동안 고자기장(${\sim}1.2Tesla$)을 발생시켰다. 시간과 펄스 주기를 순차적으로 조정 할 수 있는 다단 메쉬 방식으로 설계하여 고반복적($0.1Hz{\sim}20Hz$)으로 스위칭했을 경우에도 동일한 출력세기를 발생시킬 수 있는 자기장 의료기기 시스템을 구현하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.507-513
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• 2010

This paper is described the analysis of time-varying low-frequency electric magnetic field emitted from electric rolling stocks fed by VVVF inverter, in reference to allowable magnitude for exposures to time-varying electromagnetic field issued by International Commission on Non-Ionizing Radiation Protection(ICNIRP). The level of the magnetic field strength was measured, in reference to the standard for occupational environments, which takes into account the public person's protection against the excessive emission of the low-frequency magnetic field, 5 Hz ~ 2 kHz.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.383-384
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• 2014

This paper investigates the experimental and simulated time-varying magnetic field generation in a chlor-alkali manufacturing process. 19kA thyristor-based rectifier is modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. The mechanical structure of current carrying conductor is simplified as an infinite long busbar model and low frequency harmonic contents up to 65kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc busbar of rectifier infringing the limit of ICNIRP. Along with simulation analysis the experimental measurement of the time-varying magnetic field in ac input busbar, rectifier block, dc load and busbar are presented. The experimental test results partly confirm the simulation results.

• 한국초전도ㆍ저온공학회논문지
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• 제8권3호
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• pp.59-62
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• 2006

For electric power applications of Bi-2223/Ag superconducting tapes, a transport characteristic is important issue. A transport characteristic is strongly depends on the magnitude and direction of external time-varying magnetic field. To verify a effect of external magnetic field, we manufactured a prototype magnet and obtained transport characteristics with respect to the magnitude, the direction and the frequency of external magnetic field. The data acquired in this paper will be used as a source for the study of HTS electric power applications which is supposed to carry on.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1225-1227
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• 2005

A Bi-2223 tape has beer developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system. In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called "dynamic resistance". We developed an evaluation setup, which can measure transport loss in external at magnetic fields. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of an external ac magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of an external ac field on transport loss with different experimental conditions. This paper describes test results and discussions on correlation between the dynamic resistance and the transport loss for the Bi-2223 tape.

• 조명전기설비학회논문지
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• 제28권10호
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• pp.63-68
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• 2014

This paper deals with a methodology that applies the time-varying magnetic fields produced by the cloud discharges to find the direction of thunderstorm movement. We investigated the basic performance of the magnetic field measurement system composed of multi-turn loop-type sensors, the differential amplifier and active integrator. As a result, the response characteristics of the magnetic field sensor system to sinusoidal signals was excellent. The frequency bandwidth ranges from about 1 kHz to 500 kHz, the response sensitivity was 0.16mV/nT. In addition, we proposed the algorithm that determines the direction of lightning discharges using the comparison of the output signals of right-angled loop-type magnetic field sensors. The accuracy of the direction finding of lightning discharges is fairly well within the measurement error of less than $5^{\circ}$. The magnetic field measurement system proposed in this work can be used to track the direction of thunderstorm movement.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.232-233
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• 2010

This paper investigates occupational exposure to time-varying magnetic field generation in high power rectifier systems. Two different kinds of high power rectifier systems of 25kA are modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. In order to focus on the qualitative effect of rectifier operation, the mechanical structure of current carrying conductors is simplified as infinite long bus-bar model and low frequency harmonic contents up to 65kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc side of rectifier infringing the limit from ICNIRP. The multilevel rectifier-IGCT type has almost negligible field generation from ac input side and smaller harmonic contents in dc load side complying with ICNIRP guideline. This remarkable advantage of multilevel rectifier-IGCT type can lead to very simple site layout design for installation and cost-effective compliance to guideline of occupational exposure against magnetic field.

• 한국전기전자재료학회논문지
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• 제18권5호
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• pp.473-477
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• 2005

A Bi-2223 tape has been developed for power applications such as a fault current limiter, a power cable and a superconducting magnetic energy storage system. In such applications, the Bi-2223 tape carries time varying transport current and in addition experiences time varying external magnetic field. It is well known that the external magnetic field not only causes magnetization loss in the Bi-2223 tape, but also drastically increases transport loss due to a so-called 'dynamic resistance' We developed an evaluation setup, which can measure transport loss in external at magnetic fields. Using this equipment, we measured the dynamic resistances for various amplitudes and frequencies of an external at magnetic field perpendicular to the face in the tape. Simultaneously we investigated the effect of an external ac field on transport loss with different experimental conditions. This paper describes test results ana discussions on correlation between the dynamic resistance and the transport loss for the Bi-2223 tape.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.616-619
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• 2000

It is important to control the plasma characteristics for high quality plasma process. Recently, a novel method proposed by us, named as Enhanced-ICP, using periodic weak time-varying axial magnetic field added to a normal ICP source, has improved etch characteristics much. Variation of plasma characteristics according to the frequency of time-varying axial magnetic field have been measured and analyzed.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권10호
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• pp.509-516
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• 2001

Isolated phase bus(IPS) has a special structure for carrying large current generated by a generator to a main transformer. In the analysis of IPB, the understanding of the magnetic field distribution generated by large current is important. Especially, while the bus conductor current is flowing, almost same amount of current as bus conductor current is induced in the enclosures under the influence of time varying magnetic field, and therefore the large electric loss and the deterioration of insulating capability might occur due to Joule heating effect. Hence for the optimal design of IPB satisfying the condition to minimize the loss, the accurate analysis of magnetic field distribution and the eddy current characteristics of three phase isolated phase bus have been investigated. In the analysis of time varying magnetic field, instead of finite difference method(FDM) which is generally used, finite element method with phasor concept is investigated under the assumption that the bus current is purely sinusoidal. The characteristics is studied along the phase angle by comparing the effect of eddy current on the magnetic field distribution with the case that eddy current is not considered, and also the effect of material, thickness and radius of enclosure on the eddy current distribution is discussed.