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MMS 포인트 클라우드를 활용한 하천제방 경사도 자동 추출에 관한 연구
김철환 ( Cheolhwan Kim ),이지상 ( Jisang Lee ),최원준 ( Wonjun Choi ),김원대 ( Wondae Kim ),손홍규 ( Hong-gyoo Sohn ) 대한원격탐사학회 2021 大韓遠隔探査學會誌 Vol.37 No.5
하천 시설물의 효율적인 유지관리를 위해서는 대상물에 대해 지속적이고, 주기적인 데이터 취득이 선행되어야 한다. 하천 시설물은 일반 시설물과 달리 넓고 긴 지역을 따라 분포하고 있으므로 지상레이저스캐너, 토탈스테이션 및 GNSS를 활용하는 기존의 하천 측량 방법으로는 공간정보를 취득하는 데에 비용·인력·시간적 한계가 존재한다. 이에 반해, 모바일매핑시스템(Mobile Mapping System, 이하 MMS)은 플랫폼의 이동과 동시에 3차원 공간정보를 취득하므로 하천 시설물의 데이터 취득에 효율적이다. 따라서 본 연구진은 MMS를 활용하여 안양천 4 km 제방에 대해 20분동안 184,646,099개의 포인트를 취득했으며, 이를 10 m 간격의 종 방향으로 분할하여 378개의 횡단면을 추출하였다. 제방 횡단면 포인트 클라우드에서 제외지의 경사면 정보만 따로 분리하여 최대 및 평균 비탈 경사를 자동으로 계산하였으며, 이를 동일 제방에 대해 수동으로 계산한 값과 비교했을 때 RMSE 기준 최대 경사 1.124°, 평균 경사 1.659°의 정확도를 확인할 수 있었다. Reference 경사는 제방의 포인트 클라우드를 plot하고 경사 계산 시 위치정보를 사용하는 두 점을 직접 선택하여 수동으로 계산하였다. 또한 자동 추출한 경사를 하천기본계획 상의 비탈 경사면 설계 기준과 비교하여 MMS를 활용한 하천 시설물 검사의 가능성을 확인하였다. Continuous and periodic data acquisition must be preceded to maintain and manage the river facilities effectively. Adapting the existing general facilities methods, which include river surveying methods such as terrestrial laser scanners, total stations, and Global Navigation Satellite System (GNSS), has limitation in terms of its costs, manpower, and times to acquire spatial information since the river facilities are distributed across the wide and long area. On the other hand, the Mobile Mapping System (MMS) has comparative advantage in acquiring the data of river facilities since it constructs three-dimensional spatial information while moving. By using the MMS, 184,646,009 points could be attained for Anyang stream with a length of 4 kilometers only in 20 minutes. Levee points were divided at intervals of 10 meters so that about 378 levee cross sections were generated. In addition, the water side maximum and average slope could be automatically calculated by separating slope plane form levee point cloud, and the accuracy of RMSE was confirmed by comparing with manually calculated slope. The reference slope was calculated manually by plotting point cloud of levee slope plane and selecting two points that use location information when calculating the slope. Also, as a result of comparing the water side slope with slope standard in basic river plan for Anyang stream, it is confirmed that inspecting the river facilities with the MMS point cloud is highly recommended than the existing river survey.
고압측 오일 회수 기술을 적용한 고압식 Scroll 압축기 개발
김철환(Cheolhwan Kim),최세헌(Seheon Choi),조양희(Yanghee Cho),이병철(Byeongchul Lee) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
Recently building energy saving has been becoming one of big attentions due to global warming among EU, US and other industrial countries. As one of these building energy saving strategies, LG Electronics has developed the high efficiency high-side shell (HSS) scroll compressor for a Building Multi Air-conditioning Systems (VRF: Variable Refrigerant Flow system), which are commonly used in Asia and Europe. For high efficiency in VRF system, new oil return mechanism is developed. As the bypass loss caused by an existing oil return to low pressure side is eliminated through newly developed oil return mechanism, which is the world first structure, the system efficiency has been improved by 15% in part load condition and 5∼7% in rated cooling/heating conditions. Accordingly, these novel mechanisms can reduce annual building HVAC energy drastically. In addition, by employing a vapor injection structure the heating capacity in cold climate (-15℃) has been increased by 27% and the system efficiency has been improved by over 10%. This paper presents not only the novel oil return mechanism but the new structure of LG Electronics' HSS scroll compressor including the high efficiency brushless DC motor.