• 제목/요약/키워드: Drift region

검색결과 205건 처리시간 0.024초

Analysis of a Simulated Optical GSO Survey Observation for the Effective Maintenance of the Catalogued Satellites and the Orbit Determination Strategy

  • Choi, Jin;Jo, Jung Hyun;Yim, Hong-Suh;Choi, Young-Jun;Son, Ju-Young;Park, Sun-youp;Bae, Young-Ho;Roh, Dong-Goo;Cho, Sungki
    • Journal of Astronomy and Space Sciences
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    • 제32권3호
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    • pp.237-245
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    • 2015
  • A strategy is needed for a regional survey of geosynchronous orbits (GSOs) to monitor known space objects and detect uncataloged space objects. On the basis of the Inter-Agency Debris Committee's recommendation regarding the protected region of geosynchronous Earth orbit (GEO), target satellites with perigee and apogee of $GEO{\pm}200km$ and various inclinations are selected for analysis. The status of the GSO region was analyzed using the satellite distribution based on the orbital characteristics in publicly available two-line element data. Natural perturbation effects cause inactive satellites to drift to two stable longitudinal points. Active satellites usually maintain the designed positions as a result of regular or irregular maneuver operations against their natural drift. To analyze the detection rate of a single optical telescope, 152 out of 412 active satellites and 135 out of 288 inactive satellites in the GSO region were selected on the basis of their visibility at the observation site in Daejeon, Korea. By using various vertical view ranges and various numbers of observations of the GSO region, the detection efficiencies were analyzed for a single night, and the numbers of follow-up observations were determined. The orbital estimation accuracies were also checked using the arc length and number of observed data points to maintain the GSO satellite catalog.

Parallel PNP 및 N+ drift가 삽입된 높은 홀딩전압특성을 갖는 ESD보호회로에 관한 연구 (A Study on ESD Protection Circuit with High Holding Voltage with Parallel PNP and N+ difrt inserted)

  • 곽재창
    • 전기전자학회논문지
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    • 제24권3호
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    • pp.890-894
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    • 2020
  • 본 논문에서는 대표적인 ESD 보호소자인 LVTSCR의 구조적 변화를 통해 높은 홀딩전압 특성을 가지는 ESD 보호소자를 제안한다. 제안된 ESD 보호소자는 병렬 PNP path와 긴 N+ drift 영역을 삽입하여 기존의 LVTSCR보다 높은 홀딩전압을 가지며, 일반적인 SCR 기반 ESD보호소자의 단점인 Latch-up 면역특성을 향상시킨다. 또한 기생 BJT들의 유효 베이스 폭을 설계변수로 설정하였으며, N-Stack 기술을 적용하여 요구되는 application에 적용할 수 있도록 시놉시스사의 TCAD 시뮬레이션을 통해 제안된 ESD 보호소자의 전기적 특성을 검증하였다.

MCS-BEq 알고리즘에 의한 $SiH_4$ 기체의 전자수송특성 (Characteristics of Electron Transport in $SiH_4$ Gas used by MCS-BEq Algorithm)

  • 김상남;성낙진
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 학술대회 논문집 전문대학교육위원
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    • pp.159-162
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    • 2006
  • In this paper energy distribution function in $SiH_4$ has been analysed over the E/N range 0.5${\sim}$300Td and Pressure value 0.5, 1.0, 2.5 Torr by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The motion has been calculated to give swarm parameters for the electron drift velocity, diffusion coefficient, electron ionization, mean energy and the electron energy distribution function. The electron energy distribution function has been analysed in $SiH_4$ at E/N=30, 50Td for a case of the equilibrium region in the mean electron energy and respective set of electron collision cross sections. The results show that the deduced electron drift velocities, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients and mean energy agree reasonably well with theoretical for a rang of E/N values.

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볼츠만방정식과 몬테칼로법에 의한 $SiH_4$-Ar 혼합가스의 전자수송계수에 관한 연구 (The Study of Electron Transport coefficients in $SiH_4$-Ar Mixtures by Using Boltzmann Equation Analysis and Monte-Carlo Simulation)

  • 하성철;전병훈
    • 한국전기전자재료학회논문지
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    • 제14권2호
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    • pp.169-174
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    • 2001
  • The electron transport coefficients(the electron drift velocity, W, and the longitudinal and transverse diffusion coefficient, D$_{L}$ and D$_{T}$) in SiH$_4$-Ar mixtures containing 0.5% and 5.0% monosilane were calculated over the E/N range from 0.01 to 300 Td and over the gas pressure range 0.5, 1.0 and 1.5 Torr by the time-of-flight(TOF) method of the Boltzmann equation(BE.) and Monte-Carlo simulation(MCS). The electron energy distribution function in each SiH$_4$-Ar mixtures at E/N=10 Td and L=0.2 cm, which in equilibrium region in the mean electron enregy were compared.red.

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SOI-LDMOS의 드리프트 길이 변화에 따른 전기적 특성의 고온영역 신뢰성 분석 (The Reliability analysis on the High Temperature Characteristics of SOI-LDMOSFET Having Various Drift Region Length)

  • 김재석;구용서;구진근;안철
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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    • pp.1077-1080
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    • 2003
  • This paper show the measured result of electrical characteristics of SOI-LDMOSFET that is one of the high voltage devises. Especially, we observed changes of breakdown voltage, threshold voltage, on-resistance, drain current, and transconductance in accordance with drift length, main parameter of LDMOSFET. Also, we achieved reliability analysis about device operation in high temperature environment because LDMOS is applied to smart power IC.

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회전요동하는 원통내의 유동특성 - 이론적 해석 (Fluid Flow in a Circular Cylinder Subject to Circulatory Oscillation-Theoretical Analysis)

  • 서용권;김현민
    • 대한기계학회논문집B
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    • 제20권12호
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    • pp.3960-3969
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    • 1996
  • A fluid flow inside a circular cylinder subject to horizontal and circular oscillation is analyzed theoretically. Under the assumption of small-amplitude oscillation, the governing equations take linear forms. The velocity field is obtained in terms of the first kind of Bessel function of order 1. It was found that a particle describes an orbit close to a circle in the central region and an arc near the side wall. We also obtained the Stokes' drift velocity induced by the traveling wave along the circumferential direction. The Eulerian streaming velocities at the edge of the bottom and side boundary layers were also obtained. It was shown that the vertical component of the steady streaming velocity on the side wall is almost proportional to the amplitude of the free surface motion.

e ̄-CF$_4$산란의 전자이동속도 및 특성에너지 연구 (Electron Swarm Drift Velocity and Characteristic Energy in e$^{[-10]}$ -CF$_4$Scattering)

  • 임상원;유회영;김상남;하성철
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1996년도 추계학술대회 논문집
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    • pp.169-174
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    • 1996
  • In this paper, the electron transport characteristic in CF$_4$has been analysed over the E/N range 1~300(Td) by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The alteration of cross sections from the literature is avoided as much as possible in the analysis. The motion has been calculated to give swarm parameters for the electron drift velocity(W), diffusion coefficient(D$_{L}$), the ratio of the diffusion coefficient to the mobility(D$_{L}$/$\mu$), mean energy($\varepsilon$), the electron energy distribution function. The electron energy distribution function has been analysed in CF$_4$at E/N=50, 100 and 200(Td) for a case of the equilibrium region in the mean electron energy. The results of Boltzmann equation and Monte Carlo simulation have been compared with experimental data by Y. Nakamura and M. Hayashi.shi.

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유한수심에 놓인 부유체에 작용하는 시간평균 표류력 및 표류 모우먼트 (The Steady Drift Force and Moment on a Floating Body in Water of Finite Depth)

  • 최항순
    • 대한조선학회지
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    • 제24권1호
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    • pp.9-16
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    • 1987
  • The second-order steady horizontal force and vertical moment are derived for a freely-floating body in water of finite depth. Momentum relations are used in terms of the Kochin function in the fluid region far from the body. The general results look very similar to those for deep water. The water depth is formally reflected in terms of the ratio between the phase and group velocities of incident waves. Computations are made for a Series 60 hull($C_B=0.6$) and are compared with the corresponding results of deep water. It is shown that the vertical drift moment for slender ships becomes completely free from water depth when the wave-ship length ratio is taken as parameter.

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전자 Swarm법에 의한 $SiH_4$ 플라즈마의 전자이동속도 및 특성에너지 해석 (The Analysis of the Electron Drift Velocity and Characteristics Energy in $SiH_4$ Plasma gas by Electron Swarm method)

  • 이형윤;백승권;하성철
    • 한국전기전자재료학회논문지
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    • 제12권1호
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    • pp.88-93
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    • 1999
  • This paper describes the electron transport characteristics in $SiH_4$ gas calculated for the range of E/n:0.5~300(Td) and Pressure:0.5, 1, 2.5(Torr) by the Monte carlo simulation and Boltzmann equation method using a set of electron collision cross sections determined by the reported results. The motion has been calculated to give swarm parameters for the electron drift velocity, longitudinal and transverse diffusion coefficients, the electron ionization coefficients, characteristics energy and the electron energy distribution function. The electron energy distributions function has been analysed in $SiH_4$ at E/N: 30, 50(Td)for a case of the equilibrium region in the mean electron energy and respective set of electron collision cross sections. The results of Monte carlo simulation and Boltzmann equation have been compared with experimental data by ohmori ad Pollock.

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철근콘크리트 기둥의 내진성능 및 공학적 손상상태에 대한 실험적 평가 (Experimental Evaluation of the Seismic Performance and Engineering Damage State of Reinforced Concrete Columns)

  • 이도형
    • 한국지진공학회논문집
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    • 제27권2호
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    • pp.119-127
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    • 2023
  • In this paper, seismic performance evaluation was carried out for eight circular reinforced concrete columns designed seismically by KRTA[1]and KCI[8]. Primary design parameters for such columns included many longitudinal reinforcements, yield strength of reinforcements, the vertical spacing of spirals, aspect ratio, and axial force ratio. The test results showed that all the columns exhibited stable hysteretic and inelastic responses. Based on the test results, drift ratios corresponding to each damage state, such as initial yielding, initial cover spalling, initial core concrete crushing, buckling, and fracture of longitudinal reinforcement and final spalled region, were evaluated. Then, those ratios were compared with widely accepted damage limit states. The comparison revealed that the existing damage states were considerably conservative. This implies that additional research is required for the damage limit states of such columns designed seismically by current Korean design codes.