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Downscaling of MODIS Land Surface Temperature to LANDSAT Scale Using Multi-layer Perceptron
최유정,염재홍 한국측량학회 2017 한국측량학회지 Vol.35 No.4
Land surface temperature is essential for monitoring abnormal climate phenomena such as UHI (Urban Heat Islands), and for modeling weather patterns. However, the quality of surface temperature obtained from the optical space imagery is affected by many factors such as, revisit period of the satellite, instance of capture, spatial resolution, and cloud coverage. Landsat 8 imagery, often used to obtain surface temperatures, has a high resolution of 30 meters (100 meters rearranged to 30 meters) and a revisit frequency of 16 days. On the contrary, MODIS imagery can be acquired daily with a spatial resolution of about 1 kilometer. Many past attempts have been made using both Landsat and MODIS imagery to complement each other to produce an imagery of improved temporal and spatial resolution. This paper applied machine learning methods and performed downscaling which can obtain daily based land surface temperature imagery of 30 meters.
TRIPLE DIFFERENCE APPROACH TO LOWEARTH ORBITER PRECISION ORBIT DETERMINATION
JayHyounKwon,염재홍,이동천,DorotaA.Grejner-Brzezinska 한국우주과학회 2003 Journal of Astronomy and Space Sciences Vol.20 No.1
Aprecisekinematicorbitdetermination(P-KOD)procedureforLowEarthOrbiter(LEO)usingtheGPSion-freetripledifferencedcarrierphasesispresented. Becausethetripledifferenced observables provide only relative information, the rst epochs positionsof the orbit should be held xed. Then, both forward and backward ltering was ex-ecuted to mitigate the effect of biases of the rst epochs position. P-KOD utilizesthe precise GPS orbits and groundstations data from International GPS Service (IGS)so that the only unknown parameters to be solved are positions of the satellite at eachepoch. Currently,the3-DaccuracyofP-KODappliedtoCHAMP (CHAllengingMin-isatellite Payload) shows better than 35 cm compared to the published rapid scienticorbit (RSO) solution from GFZ (GeoForschungsZentrumPotsdam). The data screen-ing for cycle slips is a particularly challenging procedure for LEO, which moves veryfast in the middle of the ionospheric layer. It was found that data screening usingSNR (signal to noise ratio) generates best results based on the residual analysis usingRSO. It is expectedthat muchbetteraccuracyareachievablewith renedprescreeningprocedure and optimized geometry of the satellites and ground stations.
홍준표,염재홍,이효진 한국전자파학회 2002 전자파기술 Vol.13 No.4
차세대 이동 통신은 기존의 음성 서비스뿐만 아니라 훨씬 높은 용량을 필요로 하는 고품질 멀티미디어 서비스를 제공하여야 하므로 기지국의 용량을 획기적으로 증가시키는 스마트 안테나 기술이 요구되고 있다. 스마트 안테나에 대한 논의가 IMT-2000 표준화에서 활발히 이루어지고 있으며 실시간 적응알고리즘을 장착한 스마트 안테나 제품들이 상용화되어 출시되고 있는 시점이다. 본고에서는 차세대 이동통신기술로 각광받고 있는 스마트 안테나 기술의 개념, 스마트 안테나의 종류, 적응 신호 처리 알고리즘, 스마트 안테나의 IMT-2000 표준화 동향 그리고 적용 사례들을 기술하고자 한다.