• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2001년도 춘계학술발표논문집
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• pp.325-329
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• 2001

무선 단말기를 이용한 무선 인터넷 시장은 점점 커져간다. 또한, 무선 단말기에 내장 가능한 프로그램 개발도 발전하고 있다. 이 중에서도 무선 인터넷에 접속하게 하는 마이크로브라우저에 대한 개발도 이루어 졌다. 하지만, 마이크로브라우저에 관한 기능은 아직까지 미비하다. 마이크로브라우저는 HTTP 브라우저와 WAP 브라우저로 나뉘어져 있고, 현재 이들 브라우저의 제약점들을 개선하기 위해서 자바 이용하는 브라우저가 개발되고 있다. 본 논문에서 자바를 기반으로 하는 이동단말기용 마이크로브라우저에 대하여 설계 및 구현을 하였다. 자바를 사용하기 때문에 마이크로브라우저는 무선 인터넷 상에서 필요한 자바 응용 프로그램들을 다운로드 밟을 수 있고, 또 이 응용 프로그램을 단말기 내에서 실행시킬 수 있다. 따라서 자바를 기반으로 하는 마이크로브라우저는 보다 낳은 무선 인터넷 항해를 할 수 있도록 해준다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권1호
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• pp.27-33
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• 2005

The development of modern high-energy magnet materials has allowed the replacement of field coils in many different types of electromagnetic energy conversion machines. As well, the linear synchronous motor has recently been proposed for linear motion with high efficiency and thrust. Thus, this paper presents an analytical solution for the high thrust and cost reduction of the Iron-Cored Permanent Magnet Linear Synchronous Motor (PMLSM) considering magnetization arrays and geometry. Hence, the superior utilization points in each of the magnetization arrays are provided by the height ratio of the magnet/air-gap and magnet/winding coil, etc. In formulation, the space harmonic method in analytical solutions and the generalized 2-D tensor finite element analysis can be used to evaluate force components in magneto static devices including the magnetostrictive phenomenon.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권2호
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• pp.39-52
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• 2003

This paper deals with an automatic design procedure for the maximum torque density and power factor in a synchronous reluctance motor (SynRM). The focus of this paper is the design relative to the number of flux barrier and the ratio Kw of flux barrier width to iron sheet width of a SynRM under the mechanical constraint. The Finite Elements Analysis (FEA) has been used to evaluate the maximum torque density and power factor with each rotor shape. The proposed procedure allows to define the rotor geometric dimensions starling from an existing mootor or a preliminary design. The maximum torque density and power factor of a SynRM has been resulted with the rotor design variation. To prove the propriety of the designed SynRM, the Digital Signal Processor (DSP) installed experimental devices are equipped and the efficiency characteristic test is Performed.

• 제어로봇시스템학회논문지
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• 제6권11호
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• pp.963-967
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• 2000

This paper deals with a sliding mode control with uncertainty adaptation for the robust stabilization of input-delay systems with unknown uncertainties. A sliding surface including a state predictor is employed to compensate for the effect of the input delay. The proposed method does not need a priori knowledge of upper bounds on the norm of uncertainties, but estimates those upper bounds by adaptation laws based on the sliding surface. Then, a robust control law with the uncertainty adaptation is derived to ensure the existence of the sliding mode. A numerical example is given to illustrate the design procedure.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.363-375
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• 2002

The effect of the electromagnetic force (or Lorentz force) on the flow behavior around a circular cylinder is investigated by computation. Two-dimensional unsteady flow computation for Re=10$^2$is carried out using a numerical method of finite difference approximation in a curvilinear body-fitted coordinate system by solving the momentum equations including the Lorentz force as a body force. The effect of spatial variations of the Lorentz forcing region and forcing direction along the cylinder circumference is investigated. The numerical results show that the Lorentz force can effectively suppress the flow separation and oscillation of the lift force of circular cylinder cross-flow, leading to reduction of drag.

• Transactions on Control, Automation and Systems Engineering
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• 제2권2호
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• pp.98-103
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• 2000

This paper is concerned with a delay-dependent sliding mode scheme for the robust stabilization of input-delay systems with bounded unknown uncertainties. A sliding surface based ona predictor is proposed to minimize the effect of the input delay. Then, a robust control law is derived to ensure the existence of a sliding mode on the surface. In input-delay systems, uncertainties given during te delayed time are not directly controlled by the switching control because of causality prolem of them. They can influence the stability of the system in the sliding mode. Hence, a delay-dependent stability analysis for reduced order dynamics is employed to estimate maximum delay bound such that the system is globally asymptotically stable in the sliding mode. A numerical example is given to illustrate the design procedure.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2236-2249
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• 2004

The analysis for the three-dimensional fluid flow past tube banks arranged in equilateral-triangular form at Re$\_$max/=4,000 is carried out using a large eddy simulation technique. The governing equations for the mass and momentum conservation are discretized using the finite volume method. Parallel computational techniques using MPI (Message Passing Interface) are implemented in the present computer code. The computation time decreases linearly proportional to the number of used CPUs in the present parallel computation. We obtained the time-averaged streamwise and cross-streamwise velocities and turbulent intensities. The present numerical results are compared with the PIV experimental data and agree generally well with the experimental data.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1204-1209
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• 2008

Design is important in the IT, digital appliance, and auto industries. Aesthetic and art images are being applied for better design satisfaction of the products. Various artistic image patterns are used to satisfy demand of design, but it takes much lead-time and effort to implement them for making dies and molds. In this paper, a hybrid reverse engineering method generating accurate 3D engraving models from 2D art images is proposed through image processing, 3D reconstruction, and NURBS interpolation methods. In order to generate the 3D model from the 2D artistic image, cloud points with z-depth are extracted according to intensity values of the image. An adaptive median filter and harmonic filter are used to obtain the intensity values accurately. NURBS surfaces are generated through the interpolation of the cloud points. Performance of the developed system is to be confirmed through the realization of Mona Lisa and Golden Gate Bridge.

• 한국대기환경학회지
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• 제25권4호
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• pp.255-263
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• 2009

The antifungal activity of silver, copper, and titania nanoparticles against fungal spores was investigated. Cladosporium cladosporioides spores were aerosolized and sampled on a solid agar plate using an Anderson impactor. The solid agar plate contained different concentration of nanoparticles ranging from 0 to $500{\mu}g/mL$. Silver and copper nanoparticles were shown to be an effective antifungal agent, while titania nanoparticles were not. Antifungal activity of these effective nanoparticles appeared at $300{\mu}g/mL$ concentration.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.312-316
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• 2005

The single phase induction motor has been commonly applied to small-sized electrical appliances because of its low cost, but it has low efficiency and large torque ripple, and it is incapable of speed control. However, two-phase induction motors have small torque ripple, high efficiency and variable speed control, because they are inverter fed. In this paper, the dynamic characteristics of the two-phase induction motor, such as the torque ripple, current and speed, are analyzed by using the time-stepping finite element method, and compared with the cage-type single phase induction motor.