• 대한기계학회논문집A
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• 제24권7호
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• pp.1650-1660
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• 2000

Continuous casting process has been adopted increasingly in recent years to save both energy and labor. It has experienced a rapid development in the production of semi-finished steel products, rep lacing the conventional route of ingot casting and rolling. In order to achieve this merit, however, more studies about the mechanism between roll and slab are needed. In this paper, a dynamic bulging in steel cast slabs was simulated by considering the solidification and heat transfer. This study is to prevent internal cracks of a slab in a bending and unbending zone. The value of moving strand shell bulging between two supporting rollers under the ferrostatic pressure and slab-self weight has been calculated in terms of creep and elasto-plasticity. The strain and strain rate distributions in solidified shell undergoing a series of bulging are calculated with working boundary conditions.

• Journal of Communications and Networks
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• 제18권6호
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• pp.938-947
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• 2016

A mobile ad hoc network (MANET) is a collection of mobile nodes communicating in an infrastructure-less environment without the aid of a central administrating authority. Such networks entail greater dependency on synergy amongst the nodes to execute fundamental network operations. The scarcity of resources makes it economically logical for nodes to misbehave to preserve their resources which makes secure routing difficult to achieve. To ensure secure routing a mechanism is required to discourage misbehavior and maintain the synergy in the network. The proposed scheme employs a partially distributed dynamic model at each node for enhancing the security of the network. Supplementary information regarding misbehavior in the network is partially distributed among the nodes during route establishment which is used as a cautionary measure to ensure secure routing. The proposed scheme contemplates the real world scenario where a node may exhibit different kinds of misbehavior at different times. Thus, it provides a dynamic decision making procedure to deal with nodes exhibiting varying misbehaviors in accordance to their severity. Simulations conducted to evaluate the performance of the model demonstrate its effectiveness in dealing with misbehaving nodes.

• 수산해양기술연구
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• 제43권3호
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• pp.212-221
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• 2007

This paper describes on the evaluation and management of work process in suction hopper dredger and grab bucket dredger as an application of a PC-based ECDIS system. The dynamic tracking of dredging bucket and the data logging of grab dredging information were performed by using the grab dredging vessel "Kunwoong G-18". The position and route tracking of the dredger moving toward the ocean dumping site of dredged material was performed by using the hopper dredging vessel "Samyang-7". The evaluation of wok process in the dredging field, for grab dredger, was continuously carried out on January to May, 2006, in Incheon Hang and for hopper dredger, on July to December, 2003, in Busan Hang, Korea. The dredging information, such as dredger's position, heading, dredging depth and route track which was individually time stamped during the dredging operation, was automatically processed in real-time on the ECDIS and displayed simultaneously on the S-57 ENC chart. From these results, we conclude that the ECDIS system can be applied as a tool in order to manage the work process during the dredging operation, and also in order to generate the factual record of the dredging activities that is sufficient for dredging inspector to accurately evaluate the contract performance even in the absence of a full-time onboard inspector.

• 대한교통학회지
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• 제14권3호
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• pp.45-59
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• 1996

The shortest path algorithm for route guidance is implicitly required not only to support geometrical variations of transportation network such as U-TURN or P-TURN but to efficiency search reasonable routes in searching mechanism. The purpose of this paper is to integrate such two requirements ; that is, to allow U-TURN and P-TURN possibilities and to cut down searching time in locating routes between two points (origin and destination) in networks. We also propose a new type of link searching algorithm which can solve the limitation of vine building algorithm at consecutively left-turn prohibited intersections. The test site is a block of Gangnam road network that has some left-turn prohibited and allowed U-TURN intersections. Four models have been identified to be comparatively analyzed in terms of searching efficiency. The Models are as follows : (i) Model 1 - Link Searching Dijkstra Algorithm without Searching Area Extraction (SAE) ; (ii) Model 2 - Link Searching Dijkstra Algorithm with SAE ; (iii) Model 3 - Link Searching Bidirectional Dijkstra Algorithm without SAE ; and (iv) Model 4 - Link Searching Bidirectional Dijkstra Algorithm with SAE. The results of comparative evaluation show that Model 4 can effectively find optimum path faster than any other models as expected. Some discussions and future research agenda have been presented in the light of dynamic route guidance application of the urban ATIS.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (3)
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• pp.346-348
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• 2002

차량 항법 시스템(Car Navigation System)은 요즘 많은 발전을 거듭하여 차량 이용시 사용자가 가고자하는 목적지까지의 길을 쉽게 안내하고 있다. 이런 기술의 발전은 단순한 정적인 길 안내(Static Route Guidance) 뿐만 아니라. 동적인 길 안내(Dynamic Route Guidance)를 함으로써 자동차 운전자가 쉽고 빠른 길을 안내 받을 수 있게 되었다. 그러나 이러한 교통정보는 매우 변화가 심하므로 최초로 경로를 전송 받은 후 그 경로상에 교통정보가 변화하였다면, 이미 전송 받은 경로는 실시간으로 적극적으로 대응할 수 없고 실제 막히는 길로 안내할 수 있다. 목적지까지의 거리가 먼 경우 이런 현상이 더욱 심하게 나타날 수 있다. 이런 경우 운전자는 실제로는 막히는 길로 안내 받을 수 밖에 없다. 이런 문제점을 해결하기 위해 교통정보를 수집하는 기존의 시스템에 Ad Hoc 네트워킹이 가능한 시스템을 탑재한 교통정보 수집 차량(Probe Car)을 이용한다. 정보 수집 차량이 극심한 정체를 발견하면 근처를 지나는 경로를 가진 차량에게 이를 전달하여 새로운 경로를 다운받을 수 있도록 한다. 이런 방법은 Ad Hoc Relaying System〔l〕을 이용하여 가능하며, 센터에 수집되고 가공되는 시간을 최대한 줄일 수 있으며, 센터의 통신 오버헤드를 최소화할 수 있다. 또한 기지국에 호가 집중되어 call blocking이 발생함 경우에 이를 해결할 수 있다.

• 한국통신학회논문지
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• 제34권4A호
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• pp.309-315
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• 2009

무선 Ad-hoc 네트워크는 이동 노드로 구성되는 동적 네트워크이다. 일반적으로 Ad-hoc 네트워크에서 노드는 랩탑, PDA, 모바일 폰 등과 같은 장치로 블루투스나 IEEE 802.11(위피) 네트워크 인터페이스의 특징을 가지고 분산방식으로 통신을 한다. 이러한 Ad-hoc 네트워크의 특성에 기인한 이동성은 라우팅 프로토콜 디자인에 중요한 특징적 요소가 된다. 본 논문에서는 토폴로지 변화에 잘 적응하는 향상된 경로 관리 기법을 제안한다. 제안된 알고리즘에 주된 특징은 경로 실패를 방지하기 위해서 링크 단절 전에 다음-홉 노드를 대체 이웃 노드에 스위칭 하는 방식이다. NS2를 이용한 무선 Ad-hoc 네트워크의 다양한 환경에서 시뮬레이션을 수행한 결과 제안된 알고리즘 성능이 기존의 AODV 프로토콜에 비교하여 향상되었음을 보인다.

• 경영과학
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• 제33권1호
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• pp.101-117
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• 2016

In 2000s, incidence of natural disaster is increasing continuously. Therefore, the necessity of research on the effective disaster response is emphasized. Korea is not safe from natural disaster. Natural disasters like torrential downpours, typhoons have occurred more frequently than before. In addition disasters like droughts and MERS has also occurred. Therefore, needs for effective systems and algorithms to respond disaster are increased. This study covers the vehicle routing problem for effective logistics in disaster situations caused by natural disasters. The emergency vehicle route problem has different property from the general vehicle route problem. It has the property of the importance of deadline, the uncertain and dynamic demand information, and the uncertainty in information transfer. In this study, a solution that focused on the importance of deadline. In this study, the heuristic solution using the genetic algorithm are suggested. Finally the simulation experiment which reflects the actual environment are conducted to verify the performance of the solution.

• 한국통신학회논문지
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• 제29권9B호
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• pp.808-817
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• 2004

최근 Low-Rate WPAN 기술에 관한 많은 연구가 진행되고 있다. Low-Rate WPAN 은 사용자가 실질적으로 인식하지 못하는 상황에서도 주변환경에 존재하는 많은 수의 센서를 통해 컴퓨터를 이용한 개선된 서비스제공에 목적을 두고있다. Low-Rate WPAN 환경을 구성하는 센서 디 B} 이스는 빈번한 이동성을 가지게 되고 새로운 경로 탐색을 위한 메카니즘을 필요로 하게 되므로, 본 논문에서는 센서 디바이스의 위치정보를 이용한 Low-Rate WPAN 환경에서의 효율척언 라우팅 메카니즘을 제안한다. 제안한 메카니즘은 기존 방법들에 비해 라우팅 메시지 수를 감소시킬 수 있음을 시뮬레이션을 통해 입증한다.

• 한국정보통신학회논문지
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• 제6권1호
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• pp.30-35
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• 2002

동적 라우팅은 최적경로를 선택하고 라우팅테이블을 업데이트 하기 위해 라우팅 프로토콜을 사용한다. 가장 널리 사용되는 라우팅 프로토콜은 거리벡터 알고리즘을 이용한 라우팅인포메이션 프로토콜(RIP)이다. RIP는 최적경로서 최저 흡수의 경로를 취한다. 하지만 이 RIP는 매우 심각한 단점을 가지고 있다. 그것은 15 흡수 이상의 목적지에 대한 네트워크의 라우팅테이블을 유지할 수 없다는 것이다. 이를 극복하기 위해 TCP/IP에서 개발된 링크상태 프로토콜인 OSPF가 사용된다. OSPF는 큰 네트워크에 적합하고 RIP가 갖은 단점들을 극복 했다. 본 논문은 동일한 네트워크에서 메세지 전달과 지연, 링크 사용율, 메세지 전달갯수 같은 두 프로토콜사이의 트래픽과 링크효율을 분석하였다.

• International Journal of Computer Science & Network Security
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• 제24권5호
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• pp.119-128
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• 2024

The moveable ad hoc networks are untrustworthy and susceptible to any intrusion because of their wireless interaction approach. Therefore the information from these networks can be stolen very easily just by introducing the attacker nodes in the system. The straight route extent is calculated with the help of hop count metric. For this purpose, routing protocols are planned. From a number of attacks, the wormhole attack is considered to be the hazardous one. This intrusion is commenced with the help of couple attacker nodes. These nodes make a channel by placing some sensor nodes between transmitter and receiver. The accessible system regards the wormhole intrusions in the absence of intermediary sensor nodes amid target. This mechanism is significant for the areas where the route distance amid transmitter and receiver is two hops merely. This mechanism is not suitable for those scenarios where multi hops are presented amid transmitter and receiver. In the projected study, a new technique is implemented for the recognition and separation of attacker sensor nodes from the network. The wormhole intrusions are triggered with the help of these attacker nodes in the network. The projected scheme is utilized in NS2 and it is depicted by the reproduction outcomes that the projected scheme shows better performance in comparison with existing approaches.