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WRC-2000 회의의 71 GHz 이상 대역의 주파수 재분배 최종 결과
정현수,이황재,정희창,배석희,강상선,정애리,한석태,CHUNG HYUNSOO,RHEE HWANG-JAE,CHUNG HEECHANG,BAE SEOK-HEE,KANG SANG-SUN,CHUNG AEREE,HAN SEOG-TAE 한국천문학회 2000 天文學論叢 Vol.15 No.1
Radio astronomy, on its part, requires 'quiet zones' to be able to receive incoming cosmic signals unaffected by interference to enable astronomers and others learn about universe. The agenda item 1.16 of WRC-2000 contains a number of issues relevant for radio astronomy, but some of them are more important than others. The preparations for WRC-2000 have reached a close-to-final stages, with a number of proposals to this agenda item submitted to the ITU by many countries and groups of countries, like APT, CEPT and CITEL. There is no clear preference to anyone of these proposals since their differences are only minor. However, several points remain to be solved in the APT and CITEL. Fortunately, the preparation went very well, and consensus was reached on allocations above 71 GHz and three resolutions. The radio astronomy has obtained about 100 GHz of new spectrum allocations in bands above 71 GHz. In addition, a new resolution was approved by plenary meeting of WRC-2000. It deals with the consideration by a future WRC of sharing and compatibility issues between passive and active services in adjacent bands particularly with the space services (downlinks) into radio astronomy above 71 GHz. Therefore, in future, there should be a need for studies to be made to determine if and under what conditions sharing is possible, given that modifications were made on the basis of requirements known now and that little was known of requirements and implementation plans for active services in bands above 71 GHz.
정현수,정희창,이황재,배석희,강상선,정애리,한석태,CHUNG HYUNSOO,CHUNG HEECHANG,RHEE HWANG-JAE,BAE SEOK-HEE,KANG SANG-SUN,CHUNG AEREE,HAN SEOG-TAE 한국천문학회 2000 天文學論叢 Vol.15 No.1
We have analyzed the frequency sharing in the range of 71-275 GHz, which was adopted as a main topic of the WARC-2000 at the previous conference WARC-97. Though the technology of the active services has not been fully developed in this frequncy range, the heavy usage of this technology is expected in foreseeable future. To protect the passive services from spurious and out-of-band emissions of active services, realignment of the spectrum between 71 GHz and 275 GHz is strongly required. In addition, some effort should be made to allocate special bands for the radio astronomy service.
위성영상의 감독분류를 위한 훈련집합의 특징 선택에 관한 연구
곽장호 ( Jang Ho Kwak ),이황재 ( Hwang Jae Rhee ),이준환 ( Joan Whoan Lee ) 大韓遠隔探査學會 1999 大韓遠隔探査學會誌 Vol.15 No.1
위성에서 관측된 다 대역 위성영상 데이터를 이용목적에 따라 분류하기 위해서는 복잡한 처리과정과 많은 시간을 필요로 하며, 감독분류시 훈련데이터의 선택과 고려되는 다양한 특징 값들은 분류 정확도를 좌우할 만큼 민감한 특성을 나타내고 있다. 따라서 본 논문에서는 훈련데이터의 선택과 다양한 특징 값들 중 실제 영상분류에 기여도가 높은 특징을 추출하기 위하여 퍼지 기반의 γ모델을 이용한 분류네트웍을 구성하였다. 훈련집합 선택시 분류하고자 하는 지역의 밝기 분포도, 텍스쳐 특징 그리고 NDVI(Normalized Difference Vegetation Index)를 분류에 사용될 특징으로 선택하였고, 분류네트웍 출력 값의 오류가 최소화 되도록 Gradient Descent 방법을 이용하여 각 노드의 γ파라미터를 훈련시키는 과정을 채택하였다. 이러한 훈련을 통하여 얻어진 파라미터를 이용하면 각 노드의 연결특성을 알 수 있으며, 다양한 입력 노드의 특징들 중 영상분류에 기여도가 적은 특징들을 추출하여 제거할 수 있다. It is complicate and time-consuming process to classify a multi-band satellite imagery according to the applications. In addition, classification rate sensitively depends on the selection of training data set and features in a supervised classification process. This paper introduced a classification network adopting a fuzzy-based γ-model in order to select a training data set and to extract features which highly contribute to an actual classification. The features used in the classification were gray-level histogram, textures, and NDVI (Normalized Difference Vegetation Index) of target imagery. Moreover, in order to minimize the errors in the classification network, the Gradient Descent method was used in the training process for the γ-parameters at each node used. The trained parameters made it possible to know the connectivity of each node and to delete the void features from all the possible input features.