• 한국정보통신학회논문지
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• 제7권2호
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• pp.208-213
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• 2003

Ad hoc 무선망은 중앙 집중화된 관리 혹은 표준화된 지원 서비스의 도움 없이 임시 네트워크를 형성시킨 wireless mobile host들의 집합이다. 이러한 환경에서는 무선 전송 전파 범위의 한계 때문에 하나의 mobile host로 패킷을 목적지에 전송하기 위해서는 다른 host들간의 협력이 필수적이며, 경로설정 프로토콜이 중요한 요소로 여겨진다. 이론적인 면에서 On-demand 경로설정방식이 Table-driven방식보다 효율적인 방식으로 제시되고 있다. 본 논문에서는 기존에 제시된 두 가지 경로설정방식 프로토콜의 대표적인 DSDV, DSR 방식을 시뮬레이션을 통해 성능을 비교 분석하여 효율적인 라우팅 프로토콜을 제시하고자 한다.

• Journal of Communications and Networks
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• 제8권4호
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• pp.422-431
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• 2006

This paper proposes an adaptive routing protocol called ARCA for converged ad-hoc and cellular network (CACN). Due to the limitation of both bandwidth and transmission range in a cell, a mobile host (MH) may not be able to make a call during busy time. CACN offers a flexible traffic diversion mechanism that allows a MH to use the bandwidth in another cell to ease the congestion problem and increase the throughput in a cellular network. Based on the presentation of CACN's physical characteristics, the paper details the design issues and operation of the adaptive routing protocol for CACN (ARCA). Detailed numerical analysis is presented in terms of both route request rejection rate and routing overhead, which, along with the simulation results, have indicated the effectiveness and efficiency of the ARCA protocol.

• 전기전자학회논문지
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• 제25권4호
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• pp.756-761
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• 2021

Dynamic route guidance (DRG) finds the fastest path from a source to a destination location considering the real-time congestion information. In Korea, the traffic state information is available by the public transportation data (PTD) which is indexed on top of the node-link map (NLM). While the NLM is the authoritative low-detailed road network for major roads only, the OpenStreetMap road network (ORN) supports not only a high-detailed road network but also a few open-source routing engines, such as OSRM and Valhalla. In this paper, we propose a DRG framework based on road network matching between the NLM and ORN. This framework regularly retrieves the NLM-indexed PTD to construct a historical speed profile which is then mapped to ORN. Next, we extend the Valhalla routing engine to support dynamic routing based on the historical speed profile. The numerical results at the Yeoui-do island with collected 11-month PTD show that our DRG framework reduces the travel time up to 15.24 % and improves the estimation accuracy of travel time more than 5 times.

• 전자공학회논문지A
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• 제32A권1호
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• pp.222-233
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• 1995

For effective module generation, a detailed router which can handle complicated routing regions on multimple layers of interconnection under various constraints is necessary. In this paper, a new improved maze routing technique is described, which can find the shortest path for each net without allowing stacked vias. In this method, two cost values are stored at each grid point. The cost values represent the routing costs from the terminal of the net being routed to the grid point. One cost value shows the cost of the shortest path without making a via at the grid point and the other cost value shows that with making a via at the grid point. This is the first systematic maze routing technique which can find the shortest path without via-stacking.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5442-5463
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• 2016

Designing efficient routing protocols for a wireless sensor network with mobile sinks (mWSN) is a challenging task since the network topology and data paths change frequently as sink nodes move. In this paper, we design a novel lightweight reactive ring based routing protocol called R3, which removes the need of proactively maintaining data paths to mobile sinks as they move in the network. To achieve high packet delivery ratio and low transmission cost, R3 combines ring based forwarding and trail based forwarding together. To support efficient ring based forwarding, we build a ring based structure for a network in a way such that each node in the network can easily obtain its ring ID and virtual angle information. For this purpose, we artificially create a virtual hole in the central area of the network and accordingly find a shortest cycled path enclosing the hole, which serves as base ring and is used for generating the remaining ring based structure. We accordingly present the detailed design description for R3, which only requires each node to keep very limited routing information. We derive the communication overhead by ring based forwarding. Extensive simulation results show that R3 can achieve high routing performance as compared with existing work.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.2002-2019
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• 2017

RPL routing protocol for low-power and lossy networks is an Internet Engineering Task Force (IETF) recommended IPv6 based protocol for routing over Low power Lossy Networks (LLNs). RPL is proposed for networks with characteristics like small packet size, low bandwidth, low data rate, lossy wireless links and low power. RPL is a proactive routing protocol that creates a Directed Acyclic Graph (DAG) of the network topology. RPL is increasingly used for Internet of Things (IoT) which comprises of heterogeneous networks and applications. RPL proposes a single path routing strategy. The forwarding technique of RPL does not support multiple paths between source and destination. Multipath routing is an important strategy used in both sensor and ad-hoc network for performance enhancement. Multipath routing is also used to achieve multi-fold objectives including higher reliability, increase in throughput, fault tolerance, congestion mitigation and hole avoidance. In this paper, M-RPL (Multi-path extension of RPL) is proposed, which aims to provide temporary multiple paths during congestion over a single routing path. Congestion is primarily detected using buffer size and packet delivery ratio at forwarding nodes. Congestion is mitigated by creating partially disjoint multiple paths and by avoiding forwarding of packets through the congested node. Detailed simulation analysis of M-RPL against RPL in both grid and random topologies shows that M-RPL successfully mitigates congestion and it enhances overall network throughput.

• 한국정보처리학회논문지
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• 제2권3호
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• pp.406-416
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• 1995

본 논문은 이동 호스트(mobile hast)를 수용하는 컴퓨터 네트워크상에 있어 이동 호스트간의 경제성 있는 통신을 지원하는 메세지 루팅 프로토콜에 관한 것이다. 제안 된 루팅 프로토콜은 이동 호스트의 위치 이동에 따른 위치 정보의 등록을 담당하는 위치 등록 프로토콜과 이동 호스트로의 신뢰성있는 메세지 전달을 수행하는 메세지 전 달 프로토콜로 구성된다. 제안 프로토콜은 주요 특성과 동작 절차를 제안 하고, 기존 의 대표적인 프로토콜들과의 비교를 통해 제안된 프로토콜이 기능적인 측면에서는 물 론 메세지 루팅시 수반되는 통신 비용(메세지 수)에 있어서도 개선되었음을 보였다.

• 전자공학회논문지
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• 제50권11호
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• pp.141-149
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• 2013

IoT (Internet of Things) 환경에서 IPv6 패킷 통신을 지원하기 위한 표준 기술로 IETF 6LoWPAN (IPv6 over Low power WAPN) 표준 기술이 많은 연구가 진행되고 있다. 6LoWPAN에서 패킷 전송을 위한 프로토콜로 주로 AODV (Ad-hoc Distance Vector) 라우팅 프로토콜 기술을 확장한 다양한 연구가 진행되고 있다. 특히, 제한된 자원을 가진 노드들로 구성된 6LoWPAN에서 네트워크 오류가 발생했을 때 신뢰성 있는 데이터 전송과 빠른 경로 설정 방법이 필요하다. 이를 위해, 본 논문에서는 IETF LOAD(6LoWPAN Ad Hoc On-Demand Distance Vector Routing) 을 확장한 최적 복구 경로 알고리즘인 회복력 있는 라우팅 프로토콜기법 (Resilient Routing Protocol) 을 제안한다. 좀 더 구체적으로, 최적 복구 경로 설정 알고리즘, 상세 프로토콜 신호 흐름도 및 패킷 전송의 신뢰성 검증을 위한 수학적인 모델을 제시하였다. 제안된 프로토콜 기법의 성능을 분석하기 위해 NS-3 (Network Simulation Tool) 를 통해 성능 분석하였고 성능 분석 결과 기존의 LOAD 라우팅에 비해 종단간 지연시간, 패킷 처리율, 패킷 전송율 및 제어 패킷 오버헤드 등의 성능 면에서 우수함을 증명하였다.

• 대한전자공학회논문지
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• 제27권3호
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• pp.124-130
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• 1990

본 논문에서는 LSI/VLSI 레이아웃 설계 자동화를 위한 새로운 레이아웃 설계언어 HAN-LALA를 제안한다. HAN-LALA는 C언어를 확장하여 사용함으로써 레이아웃 기술이 용이하고 preprocessor없이 컴파일되므로 디버깅이 쉽고 설계 시간이 단축된다. 기술 독립적인 레이아웃 설계를 가능하게 하기 위하여 설계 규칙과 공정기술을 독립된 모듈로 구성한다. 또한 관련된 오브젝트들을 그룹으로 정의하여 그룹간 배치를 행하고, river routing, 금지 영역을 고려하여 배선 등의 다양한 배선 모듈을 제공하여 세부적인 레이아웃 기술이 없어도 오류 없는 설계가 가능하다.

• 대한산업공학회지
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• 제31권4호
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• pp.316-333
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• 2005

Although some successful recognition algorithms have been developed, most of them did emphasize on extracting accurate interpretations without considerations of manufacturability. Evaluating the manufacturability for multiple features leads to produce the machining sequences. In this paper, the A* algorithm guarantees the optimal setup sequences with minimizing the machining cost. Also, tolerances including surface roughness are converted to STEP formats to be utilized for more reliable process plans. Finally, decision tables are used to create the detailed operational sequences based on geometric tolerances and surface roughness. Machining parameters such as feed, depth of cut, and cutting speed for each operation are added to the routing sheet. Windows are presented to show how the entire system works for a sample part.