• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.810-813
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• 2003

Wide spread using of mobile and handy electronic apparatus is giving rise to a question on the harmfulness of health and causing troubles when electical and electronic equipments are in use. This paper reports on the experimental results obtained by using a pliable and structured specimen that has a long shape aperture, made of stainless steel fibers. Based on the TEM mode transfer structure that was designed and manufactured through HFSS, we measured electromagnetic shielding effectives, where the network analyzer was applied. We could draw a conclusion from this research that the metal fabric showed a good electromagnetic shielding effect, mainly by means of the good reflex loss at the fiber surface. Even though the material itself possesses a good absorption loss. the specimen revealed that structural factors. e.g.. the shape of the aperture. the size of the aperture, etc., can have a more influence on the shielding effect than the components of material have. A special notice is required for modeling and analyzing the electromagnetic characteristics of metal fabrics, because there exists a strong possibility that multiple reflection can happen on the surface of metal fibers. which can presume a model of fiber bundle and fabric structure.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.649-652
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• 1992

ECR(Electron Cyclotron Resonance) occure at ${\omega}_c$=${\omega}$, ${\omega}_c$:electron cycltron frequency, ${\omega}$:electromagnetic wave frequency. ECR system have several merit, 1) power transefer efficiency 2) low neutral gas pressure (below 1 mTorr) 3) high plasma density($10^{12}$ $cm^{-3}$). It is applicated variously in the field of semiconductor and new materials as the manufacturing equipment. Magnetic field in ECR system contruct resonance layer (${\omega}$=2.45GHz, $B_z$=875 Gauss) and control plasma. Plasma is almost generated at resonance layer. If the distance between substrate and resonance layer is short, uniformity of plasma is related with profile of resonance layer. Plasma have the property "Cold in Field", so directonality of magnetic field is one of the control factors of anisotropic etching. In this study, we calculate B field and flux line distribution, optimize geometry and submagnet current and improve of magnetic field directionality (99.9%) near substrate. For the purpose of calculation, vector potential A(r,z) and magnetic field B(r,z), green function and numerical integration is used. Object function for submagnet optimization is magnetic field directionality on the substrate and Powell method is used as optimization skim.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1729-1734
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• 2016

The surface inspection of a steel billet is a common practice in the steel manufacturing process prior to hot rolling to produce steel wire for tire cord. This billet surface inspection is an important process because flaws on the surface may cause major failures during the product manufacturing phase. This paper presents a computer simulation based on a finite element method for a magnetic flaw detector with a function of the current intensity, the number of coil turns, and the billet proceeding speed during the production phase based on the typical condition of conventional apparatus. Based on the simulation result, the magnitude of the electromagnetic field on the surface diminished with distance from the electromagnet. In addition, the increased current intensity and the increased number of coil turns actually induced a stronger electromagnetic field on the billet surface. On the other hand, the proceeding speed of a billet in its production line had no significant effects. The result in this study may assist to reduce trial and error and to minimize the opportunity costs during the optimization process by applying the findings of this study into the operation condition in the steel billet production line.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.3-12
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• 2001

Bluetooth stands for a technical specification for radio communication or a radio equipment that uses the Bluetooth specification of which the main purpose is to substitute the complicated communication cable of the informative device or electronic apparatus used at home or industrial fields, and was expected to be a mastermind of revolution in the short range radio communication. But the Bluetooth has recently been led to the mobile communication field which is somewhat apart from the primary purpose of Bluetooth and occur the question on its effectiveness. This paper review the situation of Bluetooth in the aspect of radio technical criteria and propose the direction for improvement of regulatory basis considering the prospection of the technical development of Bluetooth.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.78-81
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• 1990

The Engquist-Majdas second-order Absorbing Boundary Conditions (ABC) has been combined with the finite element formulation replacing the boundary integral equations in the hybrid finite-boundary element method (HEM). The method is applied to electromagnetic field radiation problems, especially to the microwave launcher, in order to verify the finite element formulation with the ABC's. The results with ABC are in good agreement with those of HEM. In order to see the applicability of the ABC, a simplified microwave oven utilizing ABC and an absorbing material are provided. The EM field distribution of the model is visualized. This method could be a useful analysis and design tool for EM field devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.341-342
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• 2006

A physical model for reduction of Electromagnetic Interference(EMI) or its predecessors, Radio Noise, Electrical Noise, or Radio-Frequency-Interference(RFI), is a rapidly expanding digital technology. It covers the frequency spectrum from DC to about 3 GHz EMI is the poisoner which does not allow radio, TV, radar, navigation, and a lot of electrical, electro-mechanical, and electronic and communication devices, apparatus and systems to operate compatibly in a common frequency spectrum environment EMI can result in a jammed radio, heart pacer failures, navigation errors and many other either nuisance or catastrophic events. Therefore, it follows that this spectrum pollution problem has reached international levels of concern and must be dealt with m proportion to the safety and economic impact Involved.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1063-1064
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• 2008

Bimodal tram has a carbody made of polymer composite material which is good electrical insulator. As an series hybrid type, Alternating voltage generated from generator coupled with CNG engine are rectified and transformed to variable voltage ranges which are applied to electrical apparatus and ECUs equipped inside of the tram. The failures of electrical insulation between high voltage($400V{\sim}800V$) and low voltage(24V) or between different kind of voltages such as AC and DC may cause some electrical interferences to prevent from operating rightly and other safety problem. This paper have investigated about the degradation factors of the electrical insulation and the earthing method available to bimodal tram, which is effective for preventing the electromagnetic interference coming from the inside or outside of tram but need some detecting measurements of earth leakage through electrical systems.

• Journal of Welding and Joining
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• v.33 no.1
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• pp.7-13
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• 2015

Magnetic pulse welding(MPW) is a solid state welding process that is accomplished by a magnetic pulse causing a high-velocity impact on two materials, resulting in a true metallurgical bond. One of the great advantages of MPW is that it is suitable for joining dissimilar metals. No heat affected zones are created because of the negligible heating and the clean surfaces formation that is a consequence of the jet and the metal is not degraded. Also, compared to other general welding processes, this process leads to only a low formation of brittle intermetallic compounds However, although this process has many advantages its application to industrial fields has so far been very low. Therefore, in this study we are presenting the principles, apparatus and application of MPW for application the industrial fields.

• Proceedings of the KIEE Conference
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• summer
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• pp.779-781
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• 2004

Recently, as the interests in the electrical propulsion ship increase, it is needed to prepare for the technical demand of the versatile HTS synchronous motor, the noble paradigm of the electrical motor. In this paper, the electrical propulsion apparatus was classified at first. The, the merits and demerits of the HTS synchronous motor were investigated. Finally, the feasibility study of development of the HTS motor was performed with electromagnetic FEM analysis. Additionally, the points to be considered in decision of the capacity or number of the HTS motor and the way to supply electricity were studied in this paper. This work would be very useful in establishing the development direction of the HTS motor

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.88-90
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• 2009

Extremely-Low-Frequency(ELF) magnetic fields are generated around power cables and bus bars in power systems. Such the stray fields may cause disturbances to nearby electronic apparatus and affect even human health. In order to seeking out a proper way to reducing the fields, the first thing to do is to accurately predict field distribution around analysis models of interest. Then, optimization techniques should be applied for finding a more improved design than the initial one. To achieve this goal, commercial electromagnetic software, MagNet, is combined with evolution strategy algorithm. For verification of the proposed method, three-phase power line cables and busbar systems have been tested.