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모바일 네트워크 환경에서 IEEE 802.21 MIH를 이용한 이기종간의 스케일러블 비디오 전송 방법 연구
고준호(Ko Jun-Ho),이은조(Lee Eun-Jo),박승권(Park Sung-Kwon) 한국방송·미디어공학회 2008 한국방송공학회 학술발표대회 논문집 Vol.2008 No.-
최근 유/무선 통신망과 접속 기술의 발달로 사용자들은 다양한 네트워크로의 접근이 가능하게 되었다. 하지만 이러한 여러 종류의 접속 기술은 접속 기술간 서비스 이동에 따른 이동성 보장이 서로 독립적이기 때문에 핸드오버 시 부가적인 지연이 발생하는 문제가 있다. 또한 다른 접속 서비스로의 비디오 전송 시 Qos 보장이 어려운 문제점이 있다. 따라서 본 논문에서 IEEE 802.21 Media Independent Handover 정보 서비스를 이용하여 네트워크 접속망에서 스케일러블 비디오 코딩 전송 방법을 제안한다. 이는 MIH Function에서 각 단말기에 대한 데이터 전송률과 Qos 정보를 MIH 정보 서버로부터 얻어 비디오 스케일링 레이어를 결정한다. 이렇게 결정된 스케일링 레이어를 이용하여 스케일러블 비디오 코딩을 수행한 후, 각각의 단말기에게 비디오를 전송하게 된다. 이러한 새로운 스케일러블 비디오 전송 모델은 서로 다른 여러 종류의 해상도, 화질, 프레임 전송률을 갖는 영상을 다양한 네트워크의 다양한 디바이스로 적응적인 비디오 전송이 가능하다.
고준호(Junho Ko),박철원(Chul-Won Park),김윤상(Yoon Sang Kim) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.7
최근 전력 시스템의 IT화가 본격적으로 진행되면서 전력 설비에 대한 감시를 위해 다양한 기술을 활용하여 감시시스템(monitoring system)을 구축하고자 하는 연구가 진행되고 있다. 전력 감시시스템은 전력선로와 설비에 설치되는 다양한 센서 요소로 측정된 데이터를 실시간으로 계측함으로써, 전력 시스템의 상태를 감시하는 것이 목적으로, 다중 센서들이 유/무선 통신망을 이루는 센서 네트워크로 구성된다. 본 논문은 국내 전력 감시시스템에 적용되고 있는 다양한 센서 네트워크의 유무선 통신기술사례에 대해 소개한다.
고준호 ( Joon Ho Ko ),조영재 ( Young Jae Cho ) 서울시정개발연구원 2008 연구보고서 Vol.2008 No.13
Increasing demand for the vehicle use coupled with the increasing vehicle ownership in the Seoul Metropolitan area requires more efficient travel demand management (TDM) strategies toward an optimal use of roadway facilities. In particular, the recent high-rising oil price stresses the importance of the private vehicle trip conversion to alternative modes. This study identifies that future TDM strategies should focus on the reduction of vehicle trip distance by applying value pricing and customized approaches tailored to the target groups and areas. This study recognizes that the distance-based fee system such as mileage-based insurance program, mileage-based vehicle tax, and mileage-based congestion charging would be an alternative to the current transportation policies. In fact, the distance-based system can provide an extra incentive to drive less and opportunities to save transportation costs for the drivers who intend to reduce their car reliance. Thus, the distance-based system can be a more equitable and efficient approach generating social benefits such as reduced emissions and lowered congestion levels. The three distance-based fee systems are reviewed and the effectiveness of the distance-based congestion charging system for urban expressways is evaluated. For the evaluation, two freeways, Olympic Expressway and Gang-byun-buk-ro are selected for the implementable target corridors as the two corridors are heavily congested routes running east-west along the Han River. The evaluation results indicate that an introduction of the mileage-based congestion charging system would reduce traffic demand for the corridors by 12.6%. In addition, travel speed is estimated to increase by more than 20%, little adversely affecting the whole roadway network in Seoul. These achievements from the new policy appear to be crucial in that the corridors should provide an enhanced mobility service to drivers. This study suggests that the distance-based user fee system should be a viable approach that can mitigate the external effects from traffic congestion. In particular, the system seems superior in that it is equitable and efficient to fix traveller`s behavior encouraging an use of transportation resources in an efficient manner. Future studies should identify any obstacles in adopting such policies and at the same time solutions to overcome the obstacles.
서울시 지하철체계 분석을 통한 지역별 최적 접근수단 모색
고준호 ( Joon Ho Ko ),이세희 ( Se Hee Lee ) 서울시정개발연구원 2008 연구보고서 Vol.2008 No.52
The subway system is a critical element of the urban transportation system in Seoul, covering about 35% of the total trips made in Seoul. However, it should be noted that the subway mode share has stayed at the same level even after the bus reform implemented in 2004, which incurred an increase of bus mode share from 26.0% to 27.6%. This situation implies that various efforts, including the establishment of an efficient access system to subway stations, should be made to increase the subway ridership. This study first makes an effort to identify the factors affecting the subway ridership based on regression analyses. In the analyses, district (Seoul is composed of 25 districts) was utilized as a spatial unit or a data collection unit. In doing so, the 25 districts were compared in terms of the subway modes share and subway ridership influencing factors, including the station catchment area ratio and the degree of connectivity of the transit stations within a district. In addition, access trip characteristics were identified on a district level. An interesting finding concerning the access modes is that the trunk line buses are as much used as local buses as an access mode. Local buses have been considered as a major access mode, together with walking, to subway stations. The bus reform in 2004, which introduced an unified transit fare scheme relying on only travelled distance, thus free transfer, may render the trunk line bus an another important access mode to stations. Before the bus reform, the fare of local buses was cheaper than that of trunk line buses, thus citizens preferred to using local buses as an access mode to stations. The estimated regression model with a determination coefficient of 0.79 is composed of four significant (at a significance level of 0.05) explanatory variables: degree of connectivity, ratio of station catchment area, number of local bus lines, and travel time of trunk line buses to stations. Another model with only two variables, degree of connectivity and ratio of station catchment area, showed, however, a determination coefficient of 0.70, implying these two variables can explain a significant portion of the variation associated with the subway mode share on a district level. This finding suggests that subway infra provision is a critical element as a way of attracting more passengers. This study also noted that an efficient access system should be placed as an important element that increases ridership, as suggested by the variables such as number of local bus lines and travel time of trunk line buses to stations which were identified as significant variables in the regression model. Policy makers should be advised that the subway service improvement can be achieved by obtaining adequate supports from the bus service network as well as walking environment surrounding the path to and from subway stations.