• Journal of Magnetics
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• 제17권4호
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• pp.308-315
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• 2012

Experimental investigations of the magnetization, magnetostriction and magnetoelectric (ME) effects were performed on sandwich - type Metglas/PZT/Metglas laminate composites. The results have been analyzed by taking into account the demagnetization contribution. The study has pointed out that the magnetic flux concentration is strongly improved in piezomagnetic laminates with a narrower width leading to a significant enhancement of the ME effects. The piezomagnetic laminates with the optimal area dimension were integrated to form a 2-D geomagnetic device, which simultaneously can precisely detect the strength as well as inclination of the earth's magnetic field. In this case, a magnetic field resolution of better than $10^{-4}$ Oe and an angle precision of ${\pm}0.1^{\circ}$ were determined. This simple and low-cost geomagnetic-field device is promising for various applications.

• Advances in nano research
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• 제11권6호
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• pp.581-593
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• 2021

This model is proposed to describe the buckling behavior of Carbon Nanotubes (CNTs) embedded in an elastic medium taking into account the combined effects of the magnetic field, the temperature, the nonlocal parameter, the number of walls. Using Eringen's nonlocal elasticity theory, thin cylindrical shell theory and Van der Waal force (VdW) interactions, we develop a system of partial differential equations governing the buckling response of CNTs embedded on Winkler, Pasternak, and Kerr foundations in a thermal-magnetic environment. The pre-buckling stresses are obtained by applying airy's stress function and an adjacent equilibrium criterion. To estimate the nonlocal critical buckling load of CNTs under the simultaneous effects of the magnetic field, the temperature change, and the number of walls, an optimization technique is proposed. Furthermore, analytical formulas are developed to obtain the buckling behavior of SWCNTs embedded in an elastic medium without taking into account the effects of the nonlocal parameter. These formulas take into account VdW interactions between adjacent tubes and the effect of terms involving differences in tube radii generally neglected in the derived expressions of the critical buckling load published in the literature. Most scientific research on modeling the effects of magnetic fields is based on beam theories, this motivation pushes me to develop a cylindrical shell model for studying the effect of the magnetic field on the static behavior of CNTs. The results show that the magnetic field has significant effects on the static behavior of CNTs and can lead to slow buckling. On the other hand, thermal effects reduce the critical buckling load. The findings in this work can help us design of CNTs for various applications (e.g. structural, electrical, mechanical and biological applications) in a thermal and magnetic environment.

• 대한기계학회논문집A
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• 제25권3호
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• pp.362-368
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• 2001

To design a limiting MCCB (Molded Case Circuit Breaker) mechanism, a dynamic modeling of the mechanism in which the electro-magnetic force effects are incorporated needs to be developed. Conventionally, electro-magnetic effects were considered separately for the design of the mechanism. In this paper, an electro-magnetic force that is induced by limited current is identified and included in the dynamic modeling of the mechanism. Thus, the electro-magnetic which is defined as a external force and the mechanical effects are simultaneously considered for the design of the mechanism which is composed of contactor, spring , link, latch and so on.

• Journal of Magnetics
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• 제21권2호
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• pp.255-260
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• 2016

The health effects of environmental and occupational exposure to steady magnetic fields is a matter of concern. The aim of this study was to evaluate the hematologic effects of exposure to steady magnetic fields at the electrolysis unit of a Copper complex. The population under study was the workers of the electrolysis unit of the copper refinery. The average steady magnetic field in the exposure group was 2.5 mT. The blood indices of workers exposure to steady magnetic fields after adjusting for confounders showed decreased white blood cells (except neutrophils) and increase in the number and volume of platelets. Red blood cells did not show any significant difference. Exposure to steady magnetic fields even in proposed safe limits may have hematologic effects on humans. There is a necessity for more research about the safe doses of exposure to magnetic fields.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.183.2-183.2
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• 2007

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.991-996
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• 2014

Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people's concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.

• 전기학회논문지
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• 제56권2호
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• pp.289-294
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• 2007

This paper describes the effects of rotor eccentricity in squirrel cage induction machines. Asymmetric electro-magnetic force caused by the frictional worn bearing, rotor misalignment and unbalanced rotor etc. generates an asymmetrical operation, vibration and electro-magnetic noise. The need for detection of these rotor eccentricities has pushed the development of monitoring methods with increasing sensitivity and noise immunity. In this paper, we focus on investigating the asymmetrical operation considering of unbalanced magnetic pull in squirrel-cage induction motor with 380 [V], 7.5 [kW], 4P, 1,768 [rpm]. The effects of the non-symmetric rotor and magnetic force are simulated by finite element method (FEM) and tested using search coils for measuring the actual air-gap flux.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권4호
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• pp.213-216
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• 2006

The magnetic levitation effect a high Tc superconductor beneath the toroidal permanent magnet was examined by means of a improved magnetic seesaw method. Magnetic effects associated with penetration and pinning in superconductor. One of these was focussing of magnetic field by superconductor and the other was magnetic levitation. The existence of equilibrium was shown to be related to hysteresis observed in the force separation for a toroidal permanent magnet and superconductor. Obtained results indicate that magnetic levitation effect in the present case was mainly due to diamagnetic effect.

• Journal of Welding and Joining
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• 제19권5호
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• pp.526-533
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• 2001

Induction heating of float metal products has an increasing importance in many applications, because it generates the heat within workpiece itself and provides high power densities and productivity. In this study, the induction heating of a steel plate to simulate the line heating is investigated by means of the Finite Element Analysis of the magnetic field and temperature distribution. A numerical model is used to calculate temperature distribution within the steel plate during the induction heating with a specially designed inductor. The effects of materital properties depending on the temperature and magnetic field are taken into consideration in an iterative manner. The simulation results show good magnetic field with experimental data and provide good understanding of the process. Since the numerical model demonstrates to be suitable for analysis of induction heating process, the effects of air gap and frequency on magnetic-flux and power-density distribution are also investigated. It is revealed that these process parameters have an important roles on the electro-magnetic field and power-density distribution governing the temperature distribution of the plate.

• 한국결정성장학회지
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• 제6권1호
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• pp.1-10
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• 1996

초크랄스키법에 의한 8언치 실리콘 단결정 성장시 커스프자장의 영향에 관한 수치 해석적 연구를 행하였다. 액상실리콘의 유동에 대한 모렐은 저레이놀즈수 모렐을 사용하였다. 대칭커스프자장은 유션의 강도를 감쇄하였고, 특히 도가니 벽면 근처에서의 유동의 감쇄효과가 현저하였다. 결정으로 혼업되는 산소의 농도는 인가되는 커스프자장의 증가에 따라 감소하였다. 그리고, 결정으로 혼업되는 산소농도의 균일성은 향상되었다. 비대칭커스프 자장은 결정으로 혼 입되는 산소의 농도를 중가시켰지만, 반경방향의 산소농도의 분포는 일정하게 유지되었다. 대칭 과 비대청 커스프자장의 적절한 조합을 행하면 축방향으로 일정한 산소의 분포를 갖는 적절한 조업조건이 도출될 것으로 예상된다.