• Management & Information Systems Review
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• v.29 no.4
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• pp.109-121
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• 2010

In this study, we propose a solution procedure to solve travelling salesman problem(TSP) with special cost function, route dependent travelling salesman problem(RDTSP). First, we develop an integer programming model to describe the problem. In the model, a variable means a possible route. And, the number of variables in this model are extremely large. So, we develop a LP relaxation problem of the IP model and solve the relaxation problem by a column generation technique. The relaxation problem does not guarantee the optimal solution. If we get an integer solution in the ralaxation problem, then the solution is an optimal one. But, if not, we cannot get an optimal solution. So, we approach a branch and price technique. The overall solution procedure can be applied a printed circuit board(PCB) assembly process.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.649-654
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• 2008

In the definition of non additive path, the sum of travel costs of links making up the path is not equal to the path cost. There are a variety of cases that non-additivity assumption does not hold in transportation fields. Nonetheless, traffic equilibrium models are generally built up on the fundamental hypothesis of additivity assumption. In this case traffic equilibrium models are only applicable within restrictive conditions of the path cost being linear functions of link cost. Area-wide road pricing is known as an example of realistic transportation situations, which violates such additivity assumption. Because travel fare is charged at the moment of driver's passing by exit gate while identified at entry gate, it may not be added linearly proportional to link costs. This research proposes a novel Wordrop type of traffic equilibrium model in terms of area-wide road pricing schemes. It introduces binary indicator variable for the sake of transforming non-additive path cost to additive. Since conventional shortest path and Frank-Wolfe algorithm can be applied without route enumeration and network representation is not required, it can be recognized more generalized model compared to the pre-proposed approaches. Theoretical proofs and case studies are demonstrated.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.555-556
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• 2023

본 논문에서는 제조/물류 기업 등 제품(물품) 이동 작업 시 효율적인 경로 제공을 위한 경로 최적화 기법을 제안한다. 이 기법은 업무지원 시스템(MES, ERP, WMS 등)이 구축되어있는 기업을 대상으로 공간정보와 업무지원 시스템에 저장되는 제품 데이터를 기준 정보로 하며, 다익스트라(Dijkstra), 개미 집단 알고리즘(Ant Colony Algorithm, ACO)등 경로 탐색 알고리즘을 적용하여 문제를 해결하고자 한다. 공간정보는 공장(현장)의 레이아웃(Layout)과 제품이 적재/출하되는 렉(Rack) 등의 위치 정보가 포함되고, 업무지원 시스템에서 제품의 현재 위치, 공정 상태, 등록 시간, 제품 크기 등을 사용한다. 제안하는 기법은 상기 기준 정보를 경로 탐색 알고리즘에 적용하여 적재/출하, 공정 이동, 보관 장소 변경 등 제품의 위치가 변경되는 경우에 경로를 최적화할 수 있는 기법을 제안한다. 제품 이동 작업은 대부분 노동력에 의존하는 작업으로 경로 최적화 기법을 제안함으로써, 인력 비용 감소와 향후 로봇 기반의 제품 이동 작업에도 적용하여 자동화된 작업효과를 가져다 줄 것으로 기대한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.245-248
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• 2009

Recently, Many studies have been progressing to path-finding with dynamic information on the Terminal Based Navigation System(TBNS). However, the most of existing algorithms are based on $A{\ast}$ algorithm. Path-finding algorithms which use heuristic function may occur a problem of the increase of exploring cost in case of that there is no way determined by heuristic function or there are 2 way more which have almost same cost. In this paper, two abstract graph(AG) that are different method of construction, Homogeneous Node merging($AG^H$) and Connected Node Merging($AG^C$), are implemented. The abstract graph is a simple graph of real road network. The method of using the abstract graph is proposed for reducing dependency of heuristic and exploring cost. In result of evaluation of performance, $AG^C$ has better performance than $AG^H$ at construction cost but $AG^C$ has worse performance than $AG^H$ exploring cost.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.117-130
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• 2005

In both deteministic user Optimal Traffic Assignment Model (UOTAM) and stochastic UOTAM, travel time, which is a major ccriterion for traffic loading over transportation network, is defined by the sum of link travel time and turn delay at intersections. In this assignment method, drivers actual route perception processes and choice behaviors, which can become main explanatory factors, are not sufficiently considered: therefore may result in biased traffic loading. Even though there have been some efforts in Stochastic UOTAM for reflecting drivers' route perception cost by assuming cumulative distribution function of link travel time, it has not been fundamental fruitions, but some trials based on the unreasonable assumptions of Probit model of truncated travel time distribution function and Logit model of independency of inter-link congestion. The critical reason why deterministic UOTAM have not been able to reflect route perception cost is that the route perception cost has each different value according to each origin, destination, and path connection the origin and destination. Therefore in order to find the optimum route between OD pair, route enumeration problem that all routes connecting an OD pair must be compared is encountered, and it is the critical reason causing computational failure because uncountable number of path may be enumerated as the scale of transportation network become bigger. The purpose of this study is to propose a method to enable UOTAM to reflect route perception cost without route enumeration between an O-D pair. For this purpose, this study defines a link as a least definition of path. Thus since each link can be treated as a path, in two links searching process of the link label based optimum path algorithm, the route enumeration between OD pair can be reduced the scale of finding optimum path to all links. The computational burden of this method is no more than link label based optimum path algorithm. Each different perception cost is embedded as a quantitative value generated by comparing the sub-path from the origin to the searching link and the searched link.

• The KIPS Transactions:PartC
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• v.11C no.2
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• pp.263-268
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• 2004

The end-to-end characteristic Is an important factor for QoS support. Since network users and required bandwidths for applications increase, the efficient usage of networks has been intensively investigated for the better utilization of network resources. The distributed adaptive routing is the typical routing algorithm that is used in the current Internet. The DCLC(Delay Constrained 1.east Cost) path problem has been shown to be NP-hard problem. The path cost of LD path is relatively more expensive than that of LC path, and the path delay of LC path is relatively higher than that of LD path in DCLC problem. In this paper, we investigate the performance of heuristic algorithm for the DCLC problem with new factor which is probabilistic combination of cost and delay. Recently Dr. Salama proposed a polynomial time algorithm called DCUR. The algorithm always computes a path, where the cost of the path is always within 10% from the optimal CBF. Our evaluation showed that heuristic we propose is more than 38% better than DCUR with cost when number of nodes is more than 200. The new factor takes in account both cost and delay at the same time.

• 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.13 no.11
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• pp.2367-2372
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• 2009

Recently, Many studies have been progressing to path-finding adapted dynamic information on the Terminal Based Navigation System(TBNS). The algorithms proposed are based on $A^*$ algorithm. Path-finding algorithms which use heuristic function may occur a problem of the increase of exploring cost. Path-finding with an abstract graph which expresses real road network as a simple graph is proposed for reducing dependency of heuristic and exploring cost. In this paper, two abstract graph that are different method of construction, Homogeneous Node merging($AG^H$) and Connected Node Merging($AG^C$), are implemented. In result of evaluation of performance, $AG^C$ has better performance than $AG^H$ at construction cost and the number of node access but $AG^C$ has worse performance than AGH at exploring cost.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.520-522
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• 2001

Quality-of-Service(QoS) 라우팅은 네트워크 활용률 및 사용자의 서비스 수준을 향상시킬 수 있는 장점에도 불구하고 그 복잡성 및 비용으로 인해 실제 IP 네트워크 상에 널리 기용되지 못하고 잇다. 이를 해결하기 위한 많은 연구가 이루어졌으나 기존의 분산된 경로 계산에 의존하고 있기 때문에 라우팅 성능과 프로토콜 오버헤드 간의 균형문제(trade-offs)를 해결하는데 한계가 있다. 이에 본 논문에서는 기존의 분산 QoS 라우팅의 근본적인 문제들을 해결하기 위해 중앙 집중적인 서버 기반 QoS 라우팅 메카니즘을 새로이 제안하고, 라우트 서버의 효율적인 경로 계산 및 네트워크 상태 정보 유지를 위한 방안에 대해서도 논의한다. 시뮬레이션을 통한 성능 분석 결과 서버 기반 QoS 라우팅은 정확한 네트워크 상태 정보를 사용하기 때문에 라우팅 성능 및 네트워크 활용률을 보다 더 향상시킬 수 있을 뿐 아니라, 네트워크 상태 정보의 교환이 필요하지 않기 때문에 기존의 프로토콜 오버헤드로 감소시킬 수 있음을 볼 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.399-402
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• 2013

PMIPv6(Proxy Mobile IPv6)는 네트워크 주도형 IP 기반 이동성 관리 프로토콜로서 액세스 시스템의 종류나 단말의 능력에 의존하지 않고, 단말 이동성 제어가 가능하다. 이러한 PMIPv6에 SIP 이동성을 접목하면 더 효율적인 경로를 사용해 터미널 이동성 및 세션 이동성을 확립할 수 있다. 이러한 이동성 관리를 위해 현재 PMIPv6-SIP에 대한 활발한 연구가 진행되고 있지만, 효과적인 성능평가 및 수학적 모델링이 표준화되지 못하고 있다. 이에 새로운 PMIPv6-SIP 아키텍쳐를 제안하고 핸드오버 시에 발생되는 지연과 패킷손실을 Pure-SIP과 비교하여 수학적인 모델링을 통한 효과적인 성능평가를 제안한다.