• 한국광학회지
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• 제19권1호
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• pp.80-83
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• 2008

광집게는 매질보다 큰 굴절률을 가지는 마이크로 크기의 구형 유전체를 강하게 집속되는 레이저를 이용해서 포획하고 움직이는 도구이다. 본 논문에서는 FDTD 방법을 이용해서 포획 힘을 계산하고, 그 방법을 설명하였다. 강하게 집속되는 레이저는 nonparaxial Gaussian beam을 이용해서 표현하였으며, 레이저가 대상물체와 매질에서 진행하는 것은 FDTD 방법을 이용해서 시뮬레이션 하였다. 레이저를 계산공간 전체에서 해석적으로 표현하기 위해서 scattered field formulation을 이용하였다. FDTD 방법을 이용해서 대상물체의 안팎의 전자기장을 시뮬레이션하고, 그 결과를 이용해서 Maxwell's stress tensor에 기반하여 포획 힘을 계산하였다.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1380-1385
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• 2020

An annular linear induction electromagnetic pump (ALIP) which has a developed pressure of 0.76 bar and a flow rate of 100 L/min is designed to analysis end effect which is main problem to use ALIP in thermohydraulic system of the prototype generation-IV sodium-cooled fast reactor (PGSFR). Because there is no moving part which is directly in contact with the liquid, such as the impeller of a mechanical pump, an ALIP is one of the best options for transporting sodium, considering the high temperature and reactivity of liquid sodium. For the analysis of an ALIP, some of the most important characteristics are the electromagnetic properties such as the magnetic field, current density, and the Lorentz force. These electromagnetic properties not only affect the performance of an ALIP, but they additionally influence the end effect. The end effect is caused by distortion to the electromagnetic field at both ends of an ALIP, influencing both the flow stability and developed pressure. The electromagnetic field distribution in an ALIP is analyzed in this study by solving Maxwell's equations and using numerical analysis.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권10호
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• pp.699-703
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• 1999

An experimental study to identify the energized status of the 22.9kV underground power cable by the detection of vibration has been performed. We have derived that there exists vibration at double the line frequency in live cables by electromagnetic force. The relative amplitudes of the cable vibration according to the energized status of the cable were calculated by computer simulation. The cable vibration can also be picked up by accelerometer. A prototype was tested on the underground distribution system in Chonan substation, KEPCO. Comparison between simulation results and field test results was performed. The results showed that the energized status of the calble can be identified by measuring the vibration of the cable using accelerometer.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.176-187
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• 2015

DC bias will cause abnormal vibration of transformers. Aiming at such a problem, transformer vibration affected by DC bias has been studied combined with transformer core and winding vibration mechanism use multi-physical field simulation software COMSOL in this paper. Furthermore the coupling model of electromagnetic-structural force field has been established, and the variation pattern of inner flux density, distribution of mechanical stress, tension and displacement were analyzed based on the coupling model. Finally, an experiment platform has been built up which was employed to verify the correctness of model.

• 한국정밀공학회지
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• 제15권4호
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• pp.148-155
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• 1998

It is commonly known that, in GMAW, the characteristics of metal transfer and the size of molten drop are highly dependent on the welding current. These changes in the characteristics of metal transfer has a considerable effect on the weld quality, and a lot of studies have been made on metal transfer modes for that reason. In this study, two cases were investigated; the one in which the metal transfer proceeds with gravitational force, surface tension, and no electromagnetic force, and the other in which the process has electromagnetic term in addition, where the current density in the fluid has been assumed to have Gaussian distribution on any given cross-section and it acts vertically. Using fluid flow analysis, this study has observed the whole process of the development and break-up of the molten drop, and it also showed that transitional processes, drop rate, and the drop size in each metal transfer mode can be estimated.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.613-617
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• 2011

In the present paper, a new type of electrical actuator, an electromagnetic force driving actuator (EMFA), applicable to air circuit breaker is developed and analyzed. Transient analysis is performed to obtain the dynamic characteristics of EMFA. The distribution of static magnetic flux is obtained using the finite element method. The coupled problems of electrics and mechanics governing equations are solved using the time-difference method. According to the interception rate of each contactor, investigation of the contactor spring load condition is conducted and applied to the threelink system. Comparisons of the dynamic characteristics of the three-link simulation and experimental data are performed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.194-197
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• 2009

The TR forging is a kind of continuous grain flow forging. The preform of crank shaft for TR forging process was a round bar with a ring groove. In the first stage, the preform was partly heated by induction heating and then forged by vertical and horizontal force in sequence. In this study, the simulation process of induction heating was proposed to evaluate the temperature distribution of preform for TR forging. The equivalent circuit method was adopted to find coil current of the preform with a various dimensions and power levels. With these results, the coupled electromagnetic and transient thermal analysis for induction heating was performed to evaluate the temperature distribution at the preform of crank shaft during induction heating process. This FE analysis technique with equivalent circuit method was verified by comparing the analysis results with the experimental results.

• 정보저장시스템학회논문집
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• 제6권1호
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• pp.6-11
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• 2010

Researches for actuator which is appropriate to slim optical disk drive (ODD) have been progressed for a long time. Various types of actuators are suggested to secure high performances with slim thickness. In this paper, the slim actuator with symmetric electromagnetic (EM) circuit is suggested to apply slim ODD. Various EM circuits are proposed to increase EM force in the focusing and the tracking directions. Flexible mode frequencies and driving sensitivities are increased by using stress distribution and design of experiment (DOE). Consequently, final model is suggested to have high flexible mode frequencies and driving sensitivities.

• Journal of Magnetics
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• 제22권2호
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• pp.203-213
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• 2017

Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.

• 한국광학회지
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• 제2권2호
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• pp.74-82
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• 1991

서로 마주보며 비춰진 원형편극된 두 $TEM_{00}$ 레이저 광속내에 부양된 균질구에 작용하는 광압분포를 조사하였다. 두 레이저 광속의 간섭효과를 고려하여 광압성분의 해석적 표현이 유도되었으며 정상 평면전자기파의 경우와 비교되었다. 광압분포에 대한 수치해석 결과가 제공되었으며 그 물리적 의미가 논의되었다.