• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.531-532
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• 2009

위치기반 라우팅 기법들은 소스에서 목적지노드로 데이터 패킷을 전송하기 위한 목적으로 널리 사용된다. 오리지널 그리디 포워딩 기법은 실제 무선링크의 신뢰성을 고려하지 않아 수많은 데이터 패킷 재전송이 발생한다. 이러한 문제를 해결하기 위해 PRR ${\times}$ Distance 기법이 제안되었지만 실제 무선링크의 비대칭성을 고려하지 않아 여전히 많은 재전송이 발생한다. 제안기법은 포워딩할 데이터 패킷을 가진 현재 노드의 전송 반경 내에서 전송 가능한 1-hop과 2-hop 라우팅 경로를 찾는다. 이들 라우팅 경로들 중 기대전송비용이 최소가 되는 경로를 선택하여 데이터와 ACK 패킷을 전송한다. 시뮬레이션을 결과를 통해 제안기법이 기존 기법들보다 높은 신뢰성과 에너지 효율을 가짐을 보인다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.159-160
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• 2020

4차 산업 혁명을 통해 산업 현장에서 수많은 작업들이 로봇을 이용한 자동화로 대체되고 있는 가운데, 물류 산업에서는 아직도 물건이나 화물을 피킹하고, 분류하는 과정에서 많은 인력이 동원된다. 이러한 것을 극복하기 위해 해외의 다양한 회사들이 피킹/분류 작업의 자동화를 위해 많은 연구를 하고 있다. 피킹/분류 시스템은 인력을 사용하는 과정에서 많은 인건비가 발생하고, 무거운 물건을 옮기다가 허리를 다치거나 중장비 운행 중 사고로 인해 인명 피해가 발생하기도 한다. 이러한 문제점을 개선하기 위해 목적지 까지 라인 트레이서를 통해 이동하며, 원하는 물건을 적재 하도록 로봇 암을 적용한 '자동물류분류 시스템' 기술을 제안한다. 기존의 단순 반복 노동의 피킹/분류 작업을 수행하며, 자동으로 지정된 검은 라인을 따라 이동하고, 어플리케이션을 통해 선택된 물건을 찾아가 적재하는 시스템이며, 원격으로 수동 조작 또한 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.559-562
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• 2020

시각-언어 이동 문제는 시각 이해와 언어 이해 능력을 함께 요구하는 복합 지능 문제이다. 본 논문에서는 시각-언어 이동 에이전트를 위한 새로운 학습 모델을 제안한다. 이 모델은 데모 데이터에 기초한 모방 학습과 행동 보상에 기초한 강화 학습을 함께 결합한 복합 학습을 채택하고 있다. 따라서 이 모델은 데모 데이타에 편향될 수 있는 모방 학습의 문제와 상대적으로 낮은 데이터 효율성을 갖는 강화 학습의 문제를 상호 보완적으로 해소할 수 있다. 또한, 제안 모델은 서로 다른 두 학습 간에 발생 가능한 학습 불균형도 고려하여 손실 정규화를 포함하고 있다. 또, 제안 모델에서는 기존 연구들에서 사용되어온 목적지 기반 보상 함수의 문제점을 발견하고, 이를 해결하기 위해 설계된 새로은 최적 경로 기반 보상 함수를 이용한다. 본 논문에서는 Matterport3D 시뮬레이션 환경과 R2R 벤치마크 데이터 집합을 이용한 다양한 실들을 통해, 제안 모델의 높은 성능을 입증하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.01a
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• pp.321-322
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• 2022

본 논문에서는 ROS(Robot Operating System) 기반으로 한 로봇(Robot)에 레이저 거리 센서(LiDAR)를 설치하여 SLAM(Simultaneous Localization And Mapping) 기법으로 지도 정보를 습득 및 저장하고, 이를 기반으로 맵핑된 환경과 환경 내 장애물을 회피하여 안전하고 정확하게 이동할 수 있도록 하였다. ROS는 하드웨어 추상화, 장치 드라이버, 시각화 도구, 패키지 관리 등 로봇 애플리케이션을 개발할 수 있도록 라이브러리와 도구를 제공한다. 또한 로봇 동작에 사용되는 프로세스 간 TCP-IP 통신을 통해 연동할 수 있도록 한다[1]. Ubuntu 18.04 버전의 OS에 ROS Melodic 버전을 설치해서 앱으로 선택된 목적지로 이동하는 물류 이송 로봇을 구현하였다.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.83-91
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• 2011

The objective of VMS(Variable Message Sign) is to provide the traffic information downstream to drivers upstream so that they can choose their routes or expect the travel time to arrive the destination. Because there is not enough time and space to show the message, VMS message should be selected carefully. However, the message of VMS has been simply selected among the pre-designed message sets based on the priority rule of events. If the traffic demand between origin and destination is identified along the freeway, message can be selected to provide the information of a route that more drivers will use. In this study, a time sliced OD(Origin/Destination) estimation method will be developed using the detector information of the on-ramp, exit ramp, and the main lanes. And the strategy of a priority rule of message was planned.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.763-770
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• 2014

In traditional routing protocols including LEACH for wireless sensor networks, nodes suffer from unbalanced energy consumption because the nodes require large transmission energy as the distance to the sink node increase. Multi-hop based routing protocols have been studied to address this problem. In existing protocols, each cluster head usually chooses the closest head as a relay node. We propose LEACH-CHT, in which cluster heads choose the path with least energy consumption to send data to the sink node. In our research, each hop, a cluster head selects the least cost path to the sink node. This method solves the looping problem efficiently as well as make it possible that a cluster head excludes other cluster heads placed farther than its location from the path, without additional energy consumption. By balancing the energy consumption among the nodes, our proposed scheme outperforms existing multi-hop schemes by up to 36% in terms of average network lifetime.

• Journal of the Korea Society of Computer and Information
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• v.13 no.2
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• pp.193-201
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• 2008

Using Network Coding in P2P systems yields great benefits, e.g., reduced download delay. The core notion of Network Coding is to allow encoding and decoding at intermediate nodes, which are prohibited in the traditional networking. However, improper implementation of Network Coding may reduce the overall performance of P2P systems. Network Coding cannot work with general arithmetic operations, since its arithmetic is over a Finite Field and the use of an efficient Finite Field arithmetic algorithm is the key to the performance of Network Coding. Also there are other important performance parameters in Network Coding such as Field size. In this paper we study how those factors influence the performance of Network Coding based systems. A set of experiments shows that overall performance of Network Coding can vary 2-5 times by those factors and we argue that when developing a network system using Network Coding those performance parameters must be carefully chosen.

• Journal of Korean Society of Transportation
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• v.32 no.6
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• pp.638-650
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• 2014

The objective of this study is to identify the causes of pedestrian volume path to the destination by investigating the influential levels of regional and planning features in the central area of Seoul. Regional characteristics can be classified from the result of the analysis and through the spatial characteristics of pedestrian volume. For global scale analysis, Ordinary Least Squares (OLS) regression is used for the degree of influence of each characteristics to pedestrian volume. For the local scale, Geographically Weighted Regression (GWR) is used to identify regional influential factors with consideration for spatial differences. The results of OLS indicate that boroughs with transportation facilities, commercial business districts, universities, and planning features with education research facilities and planning facilities have a positive effect on pedestrian volume path to the destination. Correspondingly, transportation hubs and congested areas, commercial and business centers, and university towns and research facilities in the Seoul central area can be identified through the results of GWR. The results of this study can provide information with relevance to existing plans and policies about the importance of regional characteristics and spatial heterogeneity effects on pedestrian volume, as well as significance in the establishment of regional development plans.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.7
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• pp.893-900
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• 2007

This paper suggests an algorithm that improves the disadvantages of the Dijkstra algorithm that is commonly used in GPS navigation system, searching for the shortest path. Dijkstra algorithm, first of all, requires much memory for the performance of the algorithm. It has to carry out number of node minus 1, since it determines the shortest path from all the nodes in the graph, starting from the first node. Therefore, Dijkstra algorithm might not be able to provide the information on every second, searching for the shortest path between the roads of the congested city and the destination. In order to solve these problems, this paper chooses a method of searching a number of nodes at once by means of choosing the shortest path of all the path nodes (select of minimum weight arc in-degree and out-degree), excluding the departure and destination nodes, and of choosing all the arcs that coincide with the shortest path of the path nodes, from all the node outgoing arcs starting from the departure node. On applying the suggested algorithm to 14 various digraphs, we succeeded to search the shortest path. In addition, the result was obtained at the speed of 2 to 3 times faster than that of Dijkstra algorithm, and the memory required was less than that of Dijkstra algorithm.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.123-130
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• 2023

As part of the research on cultural factors that determine international tourism demand, this study was conducted based on regional interest and the need for understanding religion. The purpose of this study is to empirically test how religious factors affect tourism demand in Korea to find out that religious factors are important considerations in establishing tourism policies and strategies. To achieve the purpose of this study, the research target areas were selected as Thailand, Indonesia, and the Philippines, which have relatively many tourists visiting Korea among Southeast Asian countries and are well known for their religious characteristics. GDP and nominal exchange rate, which are economic factors, were selected as explanatory variables. And religious diversity was selected as a characteristic factor variable of the tourism demand model based on the characteristic theory. An empirical analysis was conducted through a gravity model. As a result of the estimation, it was found that GDP has a positive effect on tourism demand in Korea. Nominal exchange rate variables and religious diversity variables were found to have a negative effect on tourism demand in Korea. We have confirmed that religion is an important factor in choosing tourist destinations for Filipino, Thai, and Malaysian tourists visiting Korea, and they choose religiously similar destinations.