• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.428-437
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• 2006

Wireless ad-hoc routing has been extensively studied and many clever schemes have been proposed over the last several years. One class of ad-hoc routing is geographic routing where each intermediate node independently selects the next hop using the given location information of destination. Geographic routing, which eliminates the overhead of route request packet flooding, is scalable and suitable for large scale ad hoc networks. However, geographic routing may select the long detour paths when there are voids between a source and a destination. In this paper, we propose a novel geographic routing approach called Geographic Landmark Routing(GLR). GLR recursively discovers the intermediate nodes called landmarks and constructs sub-paths that connect the subsequent landmarks. Simulation results on various network topologies show that GLR significantly improves the performance of geographic routing.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.66-75
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• 2016

Due to aggressive scaling of device sizes and reduced noise margins, physical defects caused by aging and process variation are continuously increasing. Additionally, with scaling limitation of metal wire and the increasing of communication volume, fault tolerant method in manycore network-on-chip (NoC) has been actively researched. However, there are few researches investigating reliability in NoC with voltage-frequency-island (VFI) regime. In this paper, we propose a table-based routing technique that can communicate, even if link failures occur in the VFI NoC. The output port is alternatively selected between best and the detour routing path in order to improve reliability with minimized hardware cost. Experimental results show that the proposed method achieves full coverage within 1% faulty links. Compared to $d^2$-LBDR that also considers a routing method for searching a detour path in real time, the proposed method, on average, produces 0.8% savings in execution time and 15.9% savings in energy consumption.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.131-140
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• 2012

The shortest path search algorithm of navigation is generally based on Dijkstra algorithm and considers only the distance using the weight. Dijkstra algorithm based on the distance mainly ought to perform the 'number of nodes 1' and requires a lot of memory, for it is to start from the starting node and to decide the shortest path for all the nodes. Also, it searches only the same identical path in case of any bottleneck due to an accident nearby, since it is based only on the distance, and hence does not have a system that searches the detour road. In order to solve this problem, this paper considers only the travelling time per road (travelling speed * distance), without applying speed criteria (smoothness, slow speed, stagnation and accident control) or road class (express road, national road and provincial road). This provides an advantage of searching the detour, considering the reality that there are differences in time take for the car to travel on different roads with same distance, due to any accident, stagnation, or repair construction. The suggested algorithm proves that it can help us to reach the destination within the shortest time, making a detour from any congested road (outbreak) on providing an information on traveling time continuously(real-time) even though there is an accident in a particular road.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.153-153
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• 2017

본 연구에서는 농작업지내 모서리 점을 이용하여 자율주행 트랙터의 경로점을 생성하는 알고리즘을 개발하였다. 작업지는 직사각형의 형태에서 거리가 긴 방향으로 직선주행 경로로 하고, 직선경로의 수는 작업폭에 의해 결정되며 홀수 또는 짝수 개일 수 있다. 또한 TM좌표계에서 직선주행 경로의 기울기는 양수 또는 음수 일 수 있으며, 선회시 전체적으로 좌회전 또는 우회전하는 경우로 구분하여, 즉 총 8가지의 경우에 대하여 조건이 주어지면 경로점을 구할 수 있도록 프로그램하였다. 선회를 위한 곡선경로 생성에는 트랙터의 최소 회전반경 데이터를 사용하였으며, 이때 새로 진입할 다음 경로가 충분히 떨어져 있는 경우에는 선회 구간에서도 직선 경로 구간이 생길 수 있음을 고려하였다. 한 주기의 경로점은 직선 경로 구간의 시작점과 끝점, 선회 구간의 시작점과 끝점, 다음 직선경로로 진입을 위해 선회하기 직전까지의 직선 구간에 대한 시작점과 끝점 등 6가지의 경우로 구분할 수 있다. 이때 어떤 끝점 경로점은 다음 조작 구간의 시작점 경로점이 되므로 최종적인 경로점 데이터는 4개가 된다. 여기서, 첫 번째 경로점 생성에서는 직선구간 진입을 위한 선회구간의 시작점과 끝점은 제외하였으며, 작업지로 진입할 수 있는 입구와 출구는 동일한 것으로 가정하여, 작업이 완료되는 지점에서 선회하여 다시 출발점으로 돌아올 수 있도록 추가 구성하였다. 실제 상황에서는 직선주행 경로의 수가 정수가 되지 않을 수 있으며, 이때는 작업 구간이 약간씩 오버랩되도록 작업폭을 조정하여 경로의 수가 항상 정수가 되도록 하였다. 알고리즘 평가에 사용된 작업 패턴은 관행적인 방법으로서 작업 포장을 반으로 나누어 8자형 패턴을 이용하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.8
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• pp.269-280
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• 2022

With the rise of a decentralized finance market (so called, DeFi) using blockchain technology, users and capital liquidity of decentralized finance applications are increasing significantly. The Automated Market Maker (AMM) is a protocol that automatically calculates the asset price based on the liquidity of the decentralized trading platform, and is currently most commonly used in the decentralized exchanges (DEX), since it can proceed the transactions by utilizing the liquidity pool of the trading platform even if the buyers and sellers do not exist at the same time. However, Automated Market Maker have some disadvantages since the cost efficiency of each transaction using Automated Market Maker depends on the liquidity size of some liquidity pools used for the transaction, so the smaller the size of the liquidity pool and the larger the transaction size, the smaller the cost efficiency of the trade. To solve this problem, some platforms are adopting Transaction Path Routing Algorithm that bypasses transaction path to other liquidity pools that have relatively large size to improve cost efficiency, but this algorithm can be further improved because it uses only a single transaction path to proceed each transaction. In addition to just bypassing transaction path, in this paper we proposed a Multi-Path Routing Algorithm that uses multiple transaction paths simultaneously by distributing transaction size, and showed that the cost efficiency of transactions can be further improved in the Automated Market Maker-based trading environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.3
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• pp.663-668
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• 2010

In driving a car, turns such as left turns, right turns, or u-turns, make the speed of the car decrease considerably. A more straight path, therefore, is probably faster to arrive at the destination than zig-zag path with same distance. In this paper, we have newly proposed the turn heuristic to make more straight path. The path navigation algorithm with turn heuristic(called as TA* algorithm) could enhance the straightness of a path by putting the turned-edges to the turn cost. It requires higher cost to use TA* algorithm than traditional A* algorithm because the straight-edge first searching have increased the search space. We have improved the TA* algorithm into the variable TA* algorithm(called as VTA* algorithm) which adopt the turn-heuristic during the a portion of the whole path.

• Journal of KIISE
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• v.41 no.12
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• pp.1145-1151
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• 2014

In this paper, we propose MPLO(Multi-Path routing with Local Optimization) for load balancing in the tactical backbone network. The MPLO manages global metric and local metric separately. The global metric is propagated to other routers via a routing protocol and is used for configuring loop-free multi-path. The local metric reflecting link utilization is used to find an alternate path when congestion occurs. We verified MPLO could effectively distribute user traffic among available routers by simulation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.71-74
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• 1998

본 연구는 최소비용문제에 적용할 수 있는 사전처리 기법의 이론과 그 구현에 대해서 다룬다. 일반적으로 해법을 적용하여 문제를 풀기 이전에 최적해에서 유통량을 알 수 있는 호나 중복적인 호와 점을 제거하여 문제 크기를 줄이는 과정을 사전처리(preprocessing)라 한다. 또한 문제의 비가능성이나 입력된 문제의 정확성 등을 검사하는 과정도 사전처리에 포함하기도 한다 따라서 사전처리는 문제 축소와 입력된 문제의 정확성 검사 등을 통해 해법의 수행도와 안정성을 높이는 효과를 가져다준다. 본 연구에서는 최소비용문제의 사전처리로 비가능성 판정, 중개지에 대한 사전처리, 병렬호에 대한 사전처리, 호의 유통상한과 유통하한을 이용한 유통량고정에 대한 사전처리, 우회경로에 대한 사전처리 등을 연구하였다. 본 연구에서는 네트워크 단체법 프로그램에 최소비용문제에서의 사전처리기법을 각각 구현하여 이러한 사전처리를 하지 않았을 때와 비교하여 문제의 크기를 줄일 수 있었고 수행시간을 16%정도 줄일 수 있다는 것을 실험적으로 보였다.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.354-358
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• 2005

High-rate WPAN doesn't define the time slot assignment scheduling method of CAT So, there has been many studies regarding time slot assignment scheduling of CAT. However, present studies involve demerits about not applying various types of errors in air interface or having a starvation of a specific DEV. In this paper, we propose algorithms about supplying the intermediate channel assignment in order to avoid these demerits.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.31-33
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• 2005

이동 ad-hoc 네트워크는 기반 망의 도움 없이 모바일 노드들로만 구성되어진 임시적인 네트워크이다. ad-hoc 네트워크를 구성한 모바일 노드들은 지속적인 전원공급이 힘들기 때문에 자신의 한정된 에너지에 의존한다. 이러한 모바일 노드의 에너지 소비를 줄이기 위해 IEEE 802.11 PSM를 적용한 다중 홉 ad-hoc 네트워크 모델에 대해서 최근 많은 연구가 이루어졌다. 다중 홉 ad-hoc 네트워크에 802.11 PSM을 적용하면 송수신에 참여하지 않는 모바일 노드들의 에너지소비를 절약하게 되어 네트워크 활동시간을 증가시키게 된다.