• 전기학회논문지
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• 제64권1호
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• pp.57-63
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• 2015

Fault currents characteristics contain decaying DC offset. First cycle peak value of fault currents is higher than steady-state fault current value. These characteristics can affect the operation of protective device. To reduce the asymmetric fault current, the method using a series connection of two hybrid-type Superconducting Fault Current Limiter(SFCL) components, an auxiliary SFCL and a main SFCL, has been proposed. The auxiliary SFCL limits the first half cycle fault current, while main SFCL limits the steady state fault currents. This paper proposed a decision method of the optimal insertion resistance of auxiliary and main SFCL components. To verify the effectiveness of proposed scheme, the various simulations are performed by using Electromagnetic Transient Program(EMTP).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국제학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.964-968
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• 1988

In mechanical systems in which the dynamics of armatures is dominated by electrostatic forces, motions will generally be unstable. This paper deals with the control problems of this kind of micro electrostatic device systems. In these systems, the mass of micro mechanical parts is so small that the inertia term in the equation of motion is negligible. However, nonlinear terms, such as friction and driving force, become dominant. The purpose of this paper is to realize the stable motion without delay and, overshoot etc. A micro-mechanical system used in this paper consists of a plane wafer with striped electrodes converted with an insulation layer and thin cylindrical roller is placed over on it. The performance of motions is confirmed by some simulations.

• 대한전자공학회논문지
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• 제27권10호
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• pp.89-95
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• 1990

동작 속도와 용량성 부하에 따른 최적소자크기를 결정할 수 있는 bipolar-CMOS 버퍼 모델을 제안한다. 면적 최적화를 위한 해석적 결과를 바이폴라의 고주입 효과 및 MOS의 챠넬 속도제한영역을 가정하여 구했다. BICMOS 버퍼의 면적은 용량성 부하에 거의 비례하는 에미터 길이와 챠넬 폭을 정함으로써 최적화된다는 것을 보이고, 회로 세뮬레이션 결과와 비교하여 확인하였다.

• 전자공학회논문지D
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• 제36D권4호
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• pp.70-76
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• 1999

Punchthroush 원통형 접합의 항복전압에 대한 해석적 모델을 에피층의 두께와 nonpunchthrough 원통형 접합의 항복시 임계공핍영역폭이 함수로 제안하였다. 이 해석적 모델에서의 모든 거리변수와 전계 및 전위식을 정규화된 형태로 사용하므로써 항복전압을 소자의 물리적 parameter에 관계없이 쉽게 결정할 수 있게 하였다. 제안된 모델의 계산결과를 2차원 소자 Simulation Program인 MEDICI를 사용하여 얻은 결과와 비교하여 매우 잘 일치함을 보였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.772-775
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• 2003

A bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force applied to the shaft and the relative deformation of a bushing is nonlinear and exhibits features of viscoelasticity. A force-displacement relation for bushings is important for multibody dynamics numerical simulations. For the nonlinear viscoelastic axial response, Pipkin-Rogers model, the direct relation of force and displacement, has been derived from Lianis model and the sinusoidal input was used for Pipkin-Rogers model, and the affection of displacement with frequency change was studied with Pipkin-Rogers model.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권4호
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• pp.361-366
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• 2013

A full-range analytic drain current model for depletion-mode long-channel surrounding-gate nanowire field-effect transistor (SGNWFET) is proposed. The model is derived from the solution of the 1-D cylindrical Poisson equation which includes dopant and mobile charges, by using the Pao-Sah gradual channel approximation and the full-depletion approximation. The proposed model captures the phenomenon of the bulk conduction mechanism in all regions of device operation (subthreshold, linear, and saturation regions). It has been shown that the continuous model is in complete agreement with the numerical simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.393-396
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• 1986

A Sun-Position Sensor using four phototransistors and shadow band device has been designed, and a Sun-Tracking System which tracks varying positions of the sun in elevation and azimuth axes has been built and its performance has been analyzed on the basis of indoor experiments and computer simulations. Two permanent-magnetic Step Motors (1.8.deg./step) for the main actuators and a CRC-800A kit with the Z-80CPU for the main controller have been selected to construct the Sun-Tracking System. It has been shown that the Sun-Position Sensor has about 0.5.deg. resolution and 25msec is required for the response of a single step input to reach its steady state.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.63-66
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• 2001

In this paper a binary image encryption technique and decryption system based on a joint transform correlator (JTC) are Proposed. In this method, a Fourier transform of the encrypted image is used as the encrypted data and a Fourier transform of the random phase is used as the key code. The original binary image can be reconstructed on a square law device, such as a CCD camera after the joint input is inverse Fourier transformed. The proposed encryption technique does not suffer from strong auto-correlation terms appearing in the output plane. Based on computer simulations, the proposed encryption technique and decoding system were demonstrated as adequate for optical security applications.

• 전자공학회논문지A
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• 제33A권6호
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• pp.136-143
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• 1996

A simple analytic model for the planar junctions with multiple foating field limiting rings(FLR) is presented which yields analytic expressions for the breakdown voltage and optimum ring spacings. the normalized potential of each ring is derived as a function of the normalized depletion width and the ring spacing. Based on the assumption that the breakdwon occurs simulataneously at cylindrical junctions of FLR structure where the peak sruface electric fields are equal, the optimum ring spacings are determined. The resutls are in good agreement with the simulations obtained from two dimensional device simulation program MEDICI and with the experimental data reported. The normalized experessions allow a calculation of breakdown voltage and optimum spacing over a broad range of junction depth and background doping levels.

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권2호
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• pp.102-109
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• 2007

We propose and experimentally demonstrate a ring resonator with sharp U-turns fabricated on a silicon-on-insulator (SOI) substrate; the resonator was designed as a key part of an optical, dynamic data storage device. We discuss the optical properties of the fabricated ring resonator from the viewpoint of equi-frequency-contour behavior in a dispersion space. We successfully characterize its optical characteristics on the basis of photonic crystal physics. It is suggested that the photonic ring resonator will be applicable to optical, dynamic memory devices for optical communication systems.