• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.86-89
• /
• 1991

In recent years, Vacuum Circuit Breaker(VCB) has been widely used to enhance the confidence and at the same time to ease maintenance of waterworks requipment as the power supply breaker of high voltage motor. When making and breaking the sources as VCB the powerful surge voltage, repetitive reignition phenomenon resulted from exceeding inter-pole endurance voltage of CB, has occured. It has transmitted to the winding of motor stator through the cable, and this surge voltage is repeated over and over again before finishing making and breaking action of CB according to cumulation of repetitive reignition surge, motor has become burned in the end. This paper describes surge voltage occuring in making and breaking of VCB as circuit parameters by transient phenonenon and examines closely the variance of peak values, wavefront-length, wavetail-length, when changing inductance and capacitance of a cable. Finally we will expect to protect motor winding breakdown from surge voltage through parallel connection of suitable-size in the motor.

• Bulletin of the Korean Space Science Society
• /
• 2011.04a
• /
• pp.31.1-31.1
• /
• 2011

In this study, we investigated alignment state estimation performances of the three methods i.e. merit function regression (MFR), differential wavefront sampling (DWS) and Multiple Design Configuration Optimization (MDCO). The three target optical systems are 1) a two-mirror Cassegrain system for deep space Earth observation, 2) intermediate size three-mirror anastigmat for Earth ocean monitoring, and 3) extremely large segmented optical system for astronomical observation. We ran alignment state estimation simulation for several alignment perturbation cases including 1mm to 10mm in decenter and from 0.1 to 1 degree in tilt perturbation error for the two-mirror Cassegrain system. In general, we note that MDCO shows more competitive estimation performance than MFR and DWS. The computational concept, case definition and the simulation results are discussed with implications to future works.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1958-1959
• /
• 2006

This paper proposes a local path-planning algorithm that enables a mobile robot with vision sensor in a local area.The proposed method based on projective geometry and a wavefront method finds local-paths to avoid collisions using 3-D walls or obstacles map generated using projective geometry. Simulation results show the feasibility of the proposed method

• Korean Journal of Optics and Photonics
• /
• v.11 no.4
• /
• pp.246-249
• /
• 2000

The null lens is designed for testing the elliptical (conic constant>O) mirror which is the third mirror of the off-axis Three Mirror Anastigmat (TMA) designed as a high resolution camera for remote sensing. The mixed type design is proposed as a new design type which has a small annular flat mirror, but has as twice sensitivity as the autostigmatic type design. It is also shown that the null lens of the Mixed type is better than that of the autostigmatic type in terms of the sensitivity of the wavefront distortion which is given as the magnitude of optical path difference with respect to the change of each surface parameters such as the radius of curvature, thickness of lenses and tested mirror.

• Korean Journal of Optics and Photonics
• /
• v.9 no.3
• /
• pp.151-155
• /
• 1998

A new Fabry-Perot tunable filter has been built with simple construction, which does not require any additional aligning and/or beam-confining components for the reduction of the diffraction loss. For this feature, one of the two fibers for the filter is processed to have a concave mirror whose curvature is the same as that of the wavefront of the Gaussian beam from the first fiber. After high reflection coatings, the two fibers are aligned to result in an FP filter whose bandwidth, free spectral range, and insertion loss is 1.47nm, 52nm, 5.6dB respectively.

• Progress in Superconductivity and Cryogenics
• /
• v.2 no.1
• /
• pp.24-30
• /
• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.05a
• /
• pp.367-370
• /
• 2000

Various methods of enhancing the performance of passive range sonar arrays have been discussed, triangulation, wavefront curvature method etc. But they are not appropriate to the methods because of very low SNR in underwater environment. We made appropriate sub-arrays in a linear array and applied to the beamformers such as a minimum variance with null constraints.

• Electronics and Telecommunications Trends
• /
• v.14 no.3 s.57
• /
• pp.1-18
• /
• 1999

본 고에서는 캐릭터 애니메이션을 위한 다면체 모델링 시스템에 대한 기술동향을 분석한다. 이를 위해 다면체 모델링을 지원하는 상용 캐릭터 애니메이션 소프트웨어들에 대한 최신 동향 및 이들 중 현재 고가와 중저가 시장을 주도하고 있는 Alias/Wavefront Maya 1.0 Kinetix 3D Studio Max 2.5를 중심으로 다면체 모델링 기능들을 분석하고 성능평가를 한다. 특히 기능분석에 앞서 두 시스템의 구현 개념을 살펴봄으로써 두 시스템의 다면체 모델링 기능과 더불어 전체적인 성능에 대해서도 분석한다. 이는 다면체 모델링 기능이 단순히 독립되어 구현될 수 있는 것이 아니라 전체 캐릭터 애니메이션 소프트웨어의 구조적인 구성과 밀접한 관련을 가지기 때문이다. 마지막으로 본 고는 두 상용 시스템에 대한 다면체 모델링 기능별 분류 및 그 성능평가에 대해서 벤치마킹 표로 요약. 제시하며 끝을 맺는다.

• Electronics and Telecommunications Trends
• /
• v.14 no.3 s.57
• /
• pp.31-43
• /
• 1999

본 고에서는 3차원 애니메이션을 위한 렌더링 시스템에 대한 기술동향을 분석한다. 이를 위해 렌더링을 지원하는 상용 애니메이션 소프트웨어들에 대한 최신 동향 및 이들 중 고가와 중저가 시장을 주도하고 있는 Alias/Wavefront Maya와 Kinetix 3D Studio Max를 중심으로 렌더링 기능들을 분석하고 성능평가 한다. 이를 위해 렌더링 기능으로서 Rendering Editor, Material, Lights, Textures, Ray-Tracing 및 Shadow, 카메라 및 기타 등에 대해서 각각의 기능들에 대한 특징 및 성능 등에 대해서 언급한다. 마지막으로 본 고는 두 상용 시스템에 대한 다면체 렌더링 기능별 분류 및 그 성능평가에 대해서 벤치마킹 표로 요약.제시하며 끝을 맺는다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.02a
• /
• pp.188-189
• /
• 2000

원자력 산업에서는 레이저진동측정기와 같은 원격/비접촉 측정기술이 많이 사용된다. 가동 중인 연구용 원자로의 핵연료 진동측정 같은 경우도 이러한 원격측정기술이 요구되고 있으나, 측정 대상체가 유동하는 유체 안에 있으므로 입사한 레이저의 파면이 변형되어 레이저진동측정기의 적용이 어렵다. 적응광학계(adaptive optics system; 또는 능동광학계)는 유동 층에서 변형된 파면을 파면측정 센서로 측정하고, 변형거울(deformable mirror)등의 파면보정 장치를 사용하여 파면을 보정하는 기술이다. 본 연구에서는 Shack-Hartmann 파면측정센서를 개발하고, 변형거울과 파면측정센서를 컴퓨터에 연결하여 레이저 파면의 왜곡상태를 폐회로(closed-loop)로 보정하는 장치를 개발하였다. (중략)