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RISS 인기검색어
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- 저자 : 안경환 ( Kyunghwan Ahn ) (검색결과 3 건)
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안경환 ( Kyunghwan Ahn ),임정철 ( Jeongcheol Lim ),이율경 ( Youlkyung Lee ),최태봉 ( Taebong Choi ),이광석 ( Kwangseok Lee ),임명순 ( Myoungsoon Im ),고영호 ( Youngho Go ),서재화 ( Jaehwa Suh ),신영규 ( Youngkyu Shin ),김명진 ( My 한국환경영향평가학회 2016 환경영향평가 Vol.25 No.2
Damyang riverine wetland was designated as a wetland protected area in 2004; that is located in the Yeongsan river mainstream. Total 30 phytosociological releves at field studies were classified with 22 vegetation types including of 101 species (unidentified 1 species). Legends of actual vegetation map were separated by 6 types; riparian forest, substitute vegetation, synanthropic vegetation, wet meadow vegetation, open water, an area of wetland vegetation is about 35 % (386,841.86㎡). Results of this study area as follows. The plant society of Damyang riverine wetland was conjectured that it was formed by rapidly water environment change with installed weir on the upstream of protected area and operating of Damyang dam on top of the basin. Until recently, the terrace land on the river was used to cultivate, but that would be formed fallow vegetation scenery on riverfront caused by no cultivation after designated protected area. Paspalum distichum var. indutum community designated as invasive alien plant by Korea Ministry of Environment was widely developed and Myriophyllum spicatum unrecorded in the country as newly alien species was discovered in the study zone. The plants as lapped over developing environment for Leersia japonica must be occupied habitat of native plant species having similar niche. The various plant society in Damyang riverine wetland should be developed because of environmental changes, disturbances and damages of stream.
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안경환 ( Kyunghwan Ahn ),임정철 ( Jeongcheol Lim ),한창욱 ( Changuk Han ),이윤경 ( Yunkoung Lee ),조항수 ( Hangsoo Cho ),서재화 ( Jaehwa Suh ),서민환 ( Minhwan Suh ),신영규 ( Youngkyu Shin ),김명진 ( Myungjin Kim ) 한국환경영향평가학회 2015 환경영향평가 Vol.24 No.5
The purpose of this study was to understand phytosociological characteristics and changes, providing basic ecology informations based for heronries. We investigated the 25 heronries sites to have more than a hundred nests in the country. The vegetations of heronries were arranged 8 plant communities that consisted of 60 families, 129 genuses and 167 species including 17 species of exotic species. The communities of heronries were composed of high NCD (Net Contribution Degree) of plants, such as pokeberry (Phytolacca americana), japanese chaff flower (Achyranthes japonica), asiatic dayflower (Commelina communis) including diagnosis species, that was heliophilous and tolerance of eutrophic and/or acidic soil condition, and had the highest composition with the annual plants. As locational condition, they were distributed a favorite feeding place (rice field, stream etc.) inside 0.5 km radius, and located on the eastern slope of the mountain. The vegetative composition among plants in the heronries didn’t have plant sociological characteristics for environmental conditions of the sites. But generally, they had trends in floristic composition like the areas of polluted soil, open canopy and disturbance.
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이동체 데이타베이스에서 도로 네트워크를 이용한 불확실 위치데이타의 질의처리
안성우(Sungwoo Ahn),안경환(Kyunghwan An),배태욱(Taewook Bae),홍봉희(Bonghee Hong) 한국정보과학회 2006 정보과학회논문지 : 데이타베이스 Vol.33 No.3
TPR-tree는 시간 함수 기반의 색인으로 위치 좌표와 속도 벡터 정보를 이용하여 이동체의 위치를 표현함으로써 현재 및 미래 위치 예측을 위한 질의에 사용된다. 그러나 이동체의 이동방향 및 속도가 특정 임계값을 벗어날 경우 매번 서버에 새로운 위치를 보고하기 때문에 차량과 같이 이동방향과 속도가 빈번하게 변하는 환경에 적용할 경우 서버로의 잦은 보고를 필요로 하게 되어 통신비용을 크게 증가시키는 문제가 있다. 통신비용을 일정하게 유지하기 위해서 이동체의 위치 보고를 일정한 시간 간격으로 수행하게 하는 방법이 있다. 그러나 일정한 시간 간격으로 보고되는 이동체의 위치를 저장하는 경우 보고 간격 사이에 속도와 방향이 변하게 되면 시간에 대한 선형적인 위치 예측 시에 오차가 발생하는 문제가 있다. 이 논문에서는 일정한 시간 간격으로 이동체의 위치보고가 이루어질 때 속도와 방향의 불확실성을 반영하여 이동체의 위치 예측을 위해 도로네트워크 정보를 적용한 질의 처리 기냅 및 데이타 저장 구조를 제시한다. 제시된 기법은 도로 네트워크 정보를 이용하여 이동체의 이동 방향을 도로 네트워크 세그먼트의 방향으로 제한함으로써 불확실 영역을 감소시키고 있으며 도로 네트워크 세그먼트의 종류벼리로 최대 속도를 설정하여 이동 속도의 변화에 대한 불확실성을 제거한다. 실험결과를 통하여 제안된 질의 처리 기법이 미래 위치에 대한 영역 질의 시에 False miss를 발생시키지 않으면서 False hit를 최소화 시키는 것을 확인함으로써 TPR-tree를 이용한 기존의 질의 처리 기법보다 질의 영역의 크기에 따라 최대 60% 이상 위치 예측 정확도가 향상됨을 알 수 있다. The TPR-tree is the time-parameterized indexing scheme that supports the querying of the current and projected future positions of such moving objects by representing the locations of the objects with their coordinates and velocity vectors. If this index is, however, used in environments that directions and velocities of moving objects, such as vehicles, are very often changed, it increases the communication cost between the server and moving objects because moving objects report their position to the server frequently when the direction and the velocity exceed a threshold value. To preserve the communication cost regularly, there can be used a manner that moving objects report their position to the server periodically. However, the periodical position report also has a problem that linear time functions of the TPR-tree do not guarantee the accuracy of the object's positions if moving objects change their direction and velocity between position reports. To solve this problem, we propose the query processing scheme and the data structure using road networks for predicting uncertainty positions of moving objects, which is reported to the server periodically. To reduce an uncertainty of the query region, the proposed scheme restricts moving directions of the object to directions of road network's segments. To remove an uncertainty of changing the velocity of objects, it puts a maximum speed of road network segments. Experimental results show that the proposed scheme improves the accuracy for predicting positions of moving objects than other schemes based on the TPR-tree.
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