• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.158.1-158.1
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• 2013

Microwave는 일반적으로 300 [MHz]~30 [GHz] 사이의 주파수를 가지는 전파로 1 [m] 이하의 파장을 가진다. Microwave를 이용한 플라즈마의 경우 낮은 이온 에너지, 효율적인 전자 가열, 넓은 동작압력 범위, 높은 밀도 등의 장점을 가지고 있어 PECVD(Plasma Enhanced Chemical Vapor Deposition)에 적합한 플라즈마 소스라고 할 수 있다. 또한 Microwave는 파장의 길이가 증착이 이루어지는 진공 챔버의 길이보다 매우 작기 때문에 대면적 적용성이 용이하므로 현재 많은 연구가 이루어지고 있다. 본 연구에서는 Fluid Simulation을 통해 Maxwell's equation, continuity equation, electromagnetic wave equation 등을 이용하여 Microwave의 파워 및 압력에 따른 플라즈마 parameter를 계산하고, 자체 제작한 Linear microwave plasma 장치에서 정전 탐침(Langmuir Probe)을 이용하여 플라즈마 Parameter를 측정하였다. 또한 Simulation 결과와 실험결과를 비교 분석하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.3
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• pp.181-192
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• 2012

Here in this paper, the steady paint film flow on a vertical wall of a non-Newtonian pseudo plastic fluid for drainage problem has been investigated. The exact solution of the nonlinear problem is obtained for the velocity profile. Also the average velocity, volume flux, shear stress on the wall, force to hold the wall in position and normal stress difference have been derived. We retrieve Newtonian case, when material constant ${\mu}_1$ and relaxation time ${\lambda}_1$ equal zero. The results for co-rotational Maxwell fluid is also obtained by taking material constant ${\mu}_1$ = 0. The effect of the zero shear viscosity ${\eta}_0$, the material constant ${\mu}_1$, the relaxation time ${\lambda}_1$ and gravitational force on the velocity profile for drainage problem are discussed and plotted.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1501-1505
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• 1999

Expansion dynamics of C$^{+}$ ions ejected from 355-nm laser ablation of graphite target in vacuum has been investigated by pulsed-field time-of-flight (TOF) mass spectrometry. A strong nonlinear dependence of the amount of desorbed C$^{+}$ ions on laser fluence is interpreted by the mechanism that C$^{+}$ ions are produced directly from the graphite via conversion of the multiphoton energy into thermal energy. The temporal evolution of C$^{+}$ ions was measured by varying the delay time of the ion repelling pulse with respect to the laser irradiation, which provides significant information on the ablated plume characterization. The TOF distributions of ablated ions showed a bimodal shape and could be fitted by shifted Maxwell-Boltzmann distributions. The velocity of the fast component increases with the delay time, whereas the slow component (< 500 m/s) exhibits a constant velocity. Also studied were the effects of the laser fluence on the energetics of C$^{+}$ ions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.309-317
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• 2012

Recent years have witnessed the use of micro shock tube in various engineering applications like micro combustion, micro propulsion, particle delivery systems etc. The flow characteristics occurring in the micro shock tube shows a considerable deviation from that of well established conventional macro shock tube due to very low Reynolds number and high Knudsen number effects. Also the diaphragm rupture process, which is considered to be instantaneous process in many of the conventional shock tubes, will be crucial for micro shock tubes in determining the near diaphragm flow field and shock formation. In the present study, an axi-symmetric CFD method has been applied to simulate the micro shock tube, with Maxwell's slip velocity and temperature jump boundary conditions. The effects of finite diaphragm rupture process on the flow field and the shock formation was investigated, in detail. The results show that the shock strength attenuates rapidly as it propagates through micro shock tubes.

• International Journal of Railway
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• v.3 no.1
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• pp.14-18
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• 2010

This paper describes design and characteristic analysis of long primary type linear synchronous motor (LSM) for high speed train system. LSM is designed using loading distribution method and magnetic equivalent circuit. For characteristic analysis of LSM, analytical and numerical methods are applied. Analytical method for solving the magnetic field distribution of the analytic model is based on the Maxwell’s equations. Using the characteristic equation and magnetic equivalent circuit, we analyze the effect of variation of parameters, and then we validate the result by comparing with numerical method by finite element method (FEM). We compare the analytical method with numerical method for analyzing the effect by variable parameters. This result will be useful of design and forecast of performance without FEM.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.828-832
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• 1995

This paper describes the efficient design, analysis method and experimental verification of capacitor discharge impulse magnetizer system. A capacitor discharge magnetizer system is used to produce a high current impulse of short duration in this magnetizing fixture. The parasitic resistance and parasitic inductance of the capacitor discharge impulse magnetizer system have been estimated using known air-core test coil. Finite element analysis (using MAXWELL 2-D field simulator) and magnetizing circuit analysis (using SPICE) are also used as part of the design and analysis process of the capacitor discharge impulse magnetizer system. Application study for a magnetizing fixture design is shown. 8-pole magnetizing fixture has been designed and analyzed using finite element analysis. The fixture design for 8-pole magnet are presented along with the experimental results. The experimental results have been achieved using a high-voltage, high-energy capacitor discharge impulse magnetizer and 8-pole iron core fixtures (charging voltage : 2000[V], capacitor bank : 4000[$\mu\textrm{F}$]).

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.790-794
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• 1995

Differential equations governing dynamic behavior of toroid-shaped ferro-magnetic material having a small gap of uniform width were derived incorporating Maxwell equations of electromagnetic induction relevent to the system and Newtonian equation of motion. Once the external uniform magnetic field was applied within the material through dc-circuit around the toroid, gap begin to change which lead to the abrupt variation of field in the material and gap according to the differential equations already derived. Characteristics of current and electromotive force with respect to time in the circuit consisting of inductance and resistance in series could be predicted from numerical solutions of these equations. As current in the circuit increasesl, magnetic field in the material increases, thus, the gap starts to shrink due to increased attractive force between gap and elastic restoring force in the material. With an appropriate selection of elastic constant of toroidal ferromagnetic material and design of gap structure it is possible to obtain the specified in both linear and nonlinear magnetic characteristics, such as current dependent and independent inductance.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.833-836
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• 1995

A capacitor discharge impulse magnetizer is used to produce a high current pulse of short duration in a magnetizing fixture for magnets of the various shapes. The problem of designing custom fixtures for magnetization has often been considered more of conventional experience than a scientific theory. Therefore, the design of magnetizingfixture has until recently been a "cut and try" process. It was common to literally blow up one or more fixtures beforeachieving the desired results. Finite element CAD package allow the design of such a fixture. Since magnetizing fixtures come in a variety of sizes and shapes, there is usually no simple analysis method that can be used to estimate the field characteristics of the fixtures. Instead, one typically uses finite element analysis. FEA program MAXWELL is the primary tool used here. The purpose of this study was a examine both theoretically and experimentally the field characteristics inside the fixture. Independent of sizes and shapes of magnetizing fixtures, the desired magnetic field can be obtained with resonable predictability. The experimental results have been achieved using a 1000[V], 22.4[KJ] capacitor discharge magnetizer and iron-core fixtures.

• Journal of Magnetics
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• v.20 no.1
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• pp.57-61
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• 2015

In this paper wireless power transmission system based on magnetic resonance coupling circuit was carried out. With the research objectives based on the mutual coupling model, mathematical expressions of optimal coupling coefficients are examined. Equivalent circuit parameters are calculated by Maxwell software, and the equivalent circuit was solved by Matlab software. The power transfer efficiency of the system was derived by using the electrical parameters of the equivalent circuit. System efficiency was analyzed depending on the different air gap values for various characteristic impedances. Hence, magnetic resonance coupling involves creating a resonance and transferring the power without radiating electromagnetic waves. As the air gap between the coils increased the coupling between the coils were weakened. The impedance of circuit varied as the air gap changed, affecting the power transfer efficiency.

• Journal of Magnetics
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• v.18 no.3
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• pp.250-254
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• 2013

In this research, the linear electrical generator in wave energy farm utilizing resonance power buoy system is studied. The mechanical resonance characteristics of the buoy and the wave are analyzed to maximize the kinetic energy in a relatively small wave energy area where WRPS is operated. In this research, we chose an analog model of the linear electrical generator of which size is one-hundredth of an actual size of it in WPRS (Wave energy farm utilizing Resonance Power buoy System) prior to verifying the characteristics of actual model of linear electrical generator in WRPS. In addition, the finite element analysis is conducted using commercial electromagnetic analysis software named MAXWELL to examine the electric characteristic of linear generator. Finally, for the verification of dynamic and electric characteristics of linear generator, the prototype was manufactured and the experiments to measure the displacement and the output electric power were performed.