• Journal of KIISE
• /
• v.44 no.7
• /
• pp.710-718
• /
• 2017

As graphs are becoming increasingly large, the costs for storing and managing data are increasing continuously. Shortest path discovery over a large graph requires long running time due to frequent disk I/Os and high complexity of the graph data. Recently, graph summarization techniques have been studied, which reduce the size of graph data and disk I/Os by representing highly dense subgraphs as a single super-node. Decompressing should be minimized for efficient shortest path discovery over the summarized graph. In this paper, we analyze the decompression performance of a summarized graph and propose an approximate technique that discovers the shortest path quickly with a minimum error ratio. We also propose an exact technique that efficiently discovered the shortest path by exploiting an index built on paths containing super-nodes. In our experiments, we showed that the proposed technique based on the summarized graph can reduce the running time by up to 70% compared with the existing techniques performed on the original graph.

• Journal of Broadcast Engineering
• /
• v.8 no.2
• /
• pp.136-145
• /
• 2003

This paper proposes a DTV receiver using beamforming techniques to improve indoor and mobile reception. The proposed DTV receiver estimates the directions of arrival (DOAs) of incoming signals using Capon's DOA estimation method and generates an adaptive antenna beam pattern to the estimated DOA of the mainpath signal to Improve the channel condition. After beamforming, a following decision feedback equalizer (DFE) removes the remaining multipath components. The proposed receiver can be implemented with a conventional DTV receiver without anymodification. The performance of the proposed receiver is analyzed with modified Brazilian field test models, which include DOA information of Incoming signals. Simulation results show that the proposed receiver can satisfy the threshold of visibility (TOV) when input signal to noise ratio is slightly over 10 dB.

• Journal of Korean Society of Transportation
• /
• v.26 no.6
• /
• pp.17-27
• /
• 2008

Logistic activities of shippers contains only origin-destin commodity flow information, but also contract relationships, cash flows and distribution channels. Under the lack of understanding of physical distribution channels, most studies have focused on the social and psychological aspects between manufacturers and retailers (e.g., mutual trust, power, conflict, reciprocal commitment, and so on). This study reports empirical results of distribution channel choice drawn from 2001 Korean Commodity Flow Survey(CFS) conducted by Korean government. Based on the CFS data, four distribution channels are classified. This study scrutinized how various factors including mode, commodity and firms characteristics affect distribution channel choice, and reported the problems of 2001 CFS survey questionaires and future directions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.2
• /
• pp.793-803
• /
• 2013

This study was performed to determine the usefulness of scanpath similarity analysis as one of new web usability testing. The 5 websites of public institutions were used and 15 students participated. First of all, eye movements were tracked and visual appeal ratings were measured as participants freely viewed each website for 3 seconds. Subsequently in continuously tracking the eye movements we asked the participants to perform 17 missions. Finally, in interview the participants rated on satisfaction, awareness, and mission difficulty. Results of this study showed that scanpath similarity had a significant relationship with both the visual appeal ratings(first impression) and the satisfaction. In other words, higher the visual appeal ratings were related to higher scanpath similarity. This result showed that measurement such as scanpath similarity of eye movements could become an objective index for usability testing instead of subjective evaluation such as the satisfaction. We discussed possibility that the usability testing by using the scanpath similarity with both fixation and duration on eye movements will find more appropriately inference on observers' experiences in websites.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.4
• /
• pp.354-363
• /
• 2012

Now there are a lot of expired satellites or space debris around the earth orbit and they threaten the operating satellites and manned space missions. KOMPSAT-2 that scheduled to operate the mission by July, 2013 also has to consider the space debris. This paper introduces the '25 years rules' that must be re-entered within 25 years after the space mission for LEO satellites and describes the removal trajectory design that satisfies the '25 years rules' and minimizes fuel consumption. And this paper suggests monte-carlo simulation for risk analysis that causes the approaching object to the removal trajectory. The result shows that the collision probability of worst case presents 6.0741E-07 and it need to more analysis about precise satellite safety during removal maneuver because there is no information about the object size that approaching to the satellites.

• Convergence Security Journal
• /
• v.23 no.5
• /
• pp.107-116
• /
• 2023

The management of professional manpower with expertise in performing specific tasks can be said to be a very important issue at the national level. Recently, interest in industrial technology protection experts continues to expand, but difficulties are growing due to the lack of policy evidence. Considering these points, this study conducted a fact-finding survey on personnel in charge of industrial technology protection, and through this, quantitative, qualitative, and job path analysis were performed for related job performers. These results are considered to be significant in that they can be used as basic information for fostering industrial technology protection experts in the future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2007.12a
• /
• pp.243-244
• /
• 2007

부산항에서 환적되어 일본으로 향하는 화물을 대상으로 각 일본항만까지의 해상운송에 지역별 JR(Japan Rail) 컨테이너센터까지의 내륙운송을 합한 이동경로와 비용에 관한 측면을 조사하여 이를 시나리오 분석을 이용하여 연구를 수행하였다. 일본을 네 개의 지역으로 나누어 일본의 항만을 큐슈, 동부, 중부, 관서지역으로 구분하였으며, 일본 주요대형항만과 중소형항만을 비교하여 효율적인 운송루트를 찾는 것에 중점을 두고 분석을 수행하였다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2007.10a
• /
• pp.227-230
• /
• 2007

대규모 노천광산의 개발과정에서 배수 및 운반 설계는 매우 중요한 작업 요소이며, 그 결과에 따라 채광 효율성과 광산 운영비용이 크게 달라질 수 있다. 본 연구에서는GIS를 이용하여 노천광산의 배수 및 운반 시스템을 최적화할 수 있는 새로운 채굴적 설계 방안을 제시하였다. 대부분의 노천광산에서 빈번하게 수행되는 지상 지형측량 결과를 이용하여 수치표고모델을 생성하였고, 수계분석 알고리즘을 적용하여 강우시 노천광산 배수 시스템의 특성을 분석하였다. 또한, 최적경로 분석 알고리즘과 다중 의사결정 기법을 접목하여 폐석 트럭의 최적 운반경로를 분석하고, 트럭 운반 시스템의 효율성을 평가할 수 있는 방법을 제시하였다. 인도네시아 파시르 석탄 노천광산을 대상으로 적용시험을 수행한 결과, 배수 및 운반 설계 과정에서 GIS가 효과적으로 활용될 수 있음을 확인할 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2013.05a
• /
• pp.244-247
• /
• 2013

본 논문에서는 목적지들의 중요도를 이용하여 강화학습에 의한 목적지 경로 탐색을 제안한다. 일반적인 목적지 경로탐색은 목적지의 중요도나 방문빈도를 고려하지 않는 최단경로탐색을 수행한다. 그러므로 방문객들의 요구에는 맞지 않는 경로를 탐색한다. 강화학습의 특징은 관심 대상에 대한 구체적인 지배 규칙의 정보 없이도 최적화된 행동 방식을 학습시킬 수 있는 특징이 있다. 이를 이용하면 주요목적지를 누락시키지 않고 방문객들의 요구에 만족하는 경로를 탐색할 수 있다. 기존에 이용되고 있는 경로탐색 알고리즘과 강화학습기법이 적용된 알고리즘을 서로 분석하여 비교한다.

• Proceedings of the Korea Contents Association Conference
• /
• 2004.11a
• /
• pp.369-373
• /
• 2004

이동 가입자에 대한 효율적인 이동성 관리는 이동통신망에서 매우 중요한 역할을 한다. 본 논문에서는 이동기준 위치등록(MBR) 방식을 개선한 새로운 위치등록 방식을 제안한다. 기본 아이디어는 위치등록 수행 후 이동국의 이동경로를 내부 메모리에 기억하고 있다가 이동 가입자가 최근에 위치등록을 수행한 셀의 주변에서 이동하는 경우 불필요한 위치등록이 일어나지 않도록 하는 것이다. 제안한 방식의 분석은 이동기준 위치등록 방식과의 비교를 통하여 수행하였다. 분석 결과 제안한 방식은 이동기준 위치등록 방식에 비해 위치등록 회수가 작아서 그 성능이 우수함을 알 수 있었다.