• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.267-271
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• 2004

The satellite in the geostationary orbit rotates around Earth center with the same angular rate as the Earth. So, the Earth can be observed with sequential time series. GOES(Geostationary Operational Environmental Satellites)-9 is a meteorological satellite, which is now located at 155ㆁE geostationary orbit location in order to monitor East-Asia meteorological environment including Korean Peninsular. Every meteorological information is acquired from GOES-9 with the period of about 1 hour. COMS(Communication, Ocean and Meteorological Satellite) has been developed by KARI(Korea Aerospace Research Institute) since 2003 and will be launched at 2008. COMS will be located at different orbit location compared to GOES-9. In this study, a simulated COMS image which is the perspective from different geostationary orbit location is generated using an GOES-9 image.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.405-411
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• 2009

Railway signaling system in a rapid transit using the ATC system the approved a speed limit to a train and a part of signaling system in a metro approved a distance which is possible to move. Referring to the way of transmitting train control information, there are the one transmitting it to the on-board system of a train using the direct track, the another transmitting it establishing an instrument, and the other transmitting an instrument by a railway track. The one is the method using the direct track as a conductor for composing the part of the track and attaining the information controlling a train by transmitting a signal to the track. It is used for the high-speed railway and the subway. The method using the track attains information by transmitting it to returned information, and the on-board system of a train attains it by magnetic coupling. Because many reinforcing bars on the concrete slab track are used, interaction between a rail and a reinforcing bar that is not produced on ballast track is made. Due to the interaction, the electric characteristic of rail is changed. In the current paper, we numerically computed the coupling coefficient between the rail and the reinforcing bar based on the concrete slab track throughout the model related to the rail and the reinforcing bar using the concrete slab track that is used in the second interval of the Gyeongbu high-speed railway, and we defined the coupling coefficient not changed in the electric characteristic of rail in the condition that there is no interaction between the rail and the reinforcing bar.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.120.2-120.2
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• 2012

천리안위성은 2010년 6월 발사되어 지구적도상공 약36,000km, 동경 128.2도에 위치하고 지구 자전 방향으로 지구와 같은 속도로 회전하며 24시간 한반도를 관측하는 정지궤도위성이다. 정지궤도위성은 높은 고도로 인하여 태양활동 변화에 따른 태양풍, 고에너지 전자 등에 의한 영향을 직접적으로 받는 환경에 놓여있다. 과거 사례들로부터 정지궤도위성의 오작동은 태양활동에 의해 다양한 현상으로 발생될 수 있다는 사실도 밝혀졌다. 본 연구에서는 2013년 태양활동 극대기를 대비하여 태양활동 변화가 천리안위성의 탑재체에 끼치는 영향에 대해 조사되었다. 천리안위성은 기상 해양관측을 위한 광학탑재체와 통신서비스를 위한 통신탑재체로 이루어져있다. 이 중 우리는 2011년에 발생된 X등급의 태양폭발 규모에 따라서 기상관측을 수행하는 기상탑재체 상태가 태양폭발이 없는 기간의 상태와 어느 정도 차이를 보이는지 분석하였다. 2011년에 발생된 경보는 3단계 10회, 4단계 2회로 발생빈도가 증가하는 추세이다. 4단계 경보의 태양폭발에도 천리안위성은 모든 부분에서 정상운영을 유지하고 있다. 이번연구를 통해 태양폭발 규모에 따른 기상탑재체의 영향 정도를 가시화하여 앞으로 발생 가능한 문제를 예측하고 대비함으로서 안정적인 위성운영을 도모하고자 한다.

• Journal of Korean Electronics
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• v.1 no.11
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• pp.58-61
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• 1981

• Photonics industry news
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• s.7
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• pp.66-67
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• 2001

• Journal of Korean Electronics
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• v.25 no.8
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• pp.15-15
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• 2005

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.583-588
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• 2010

Track irregularities is one of key factors influencing running behavior of train. In order to ensure safety and ride comfort, it is highly important that relationship between track irregularity and running behavior of vehicle is identified and the criteria for track irregularities is adequately established. Numerical analysis was conducted to investigate influence of surface on running behavior of KTX and various wavelength and amplitude of surface were considered in numerical analysis. Derailment, lateral load, bogie acc., body acc. of numerical analysis results were investigated to evaluate the effect on track profile on safety and ride comfort of KTX.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.659-664
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• 2020

In this paper, we propose a silicon-based electro-optic (EO) modulator which can modulate a sign of a topological charge number l of |l|=1 orbital angular momentum (OAM) mode. The proposed EO modulator consists of position-dependent doped Si waveguide core and undoped SiO2, cladding, which enables control of the effective index and propagation loss of two OAM constitutive eigenmodes. The modulator functions as OAM mode maintaining waveguide at -0.33V and as topological charge sign inverter at 10V. The output OAM mode purity is calculated through electric field distribution, showing high purity of |l|>0.92 in both cases.

• Defense and Technology
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• no.1 s.37
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• pp.7-15
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• 1982

• Defense and Technology
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• no.7 s.209
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• pp.30-37
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• 1996