• 대한산업공학회지
• /
• 제27권3호
• /
• pp.250-259
• /
• 2001

Given a tree structured network in which each node has its own demand and also stands for a candidate location of a potential facility, such as plant or warehouse, a capacitated facility location problem on the network (CFLPOT) is to decide capacitated facility locations so that the total demand occurred on the network can be satisfied from those facilities with the minimum cost. In this paper, we first introduce a mixed integer programming formulation for CFLPOT with two additional assumptions, the indivisible demand assumption and the contiguity assumption and then show that it can be reformulated as a tree partitioning problem with an exponential number of variables. We then show that it can be solved in O($n^2b$) time by utilizing the limited column generation method developed by Shaw (1993), where n is the total number of nodes in the network and b is the maximum facility capacity. We also develop a depth-first dynamic programming algorithm with a running time of O(nb) for finding the locally maximal reduced cost which plays an important role in the limited column generation method. Finally, we implement our algorithms on a set of randomly generated problems and report the computational results.

• 산업공학
• /
• 제20권3호
• /
• pp.395-406
• /
• 2007

In the telecommunication industry, estimation of the cost of network facilities is very important since depreciation cost of the facilities accounts for a large portion of the product cost. Moreover, cost estimation in the industry becomes more difficult because of increasing indirect cost upon digital convergence, expanding multi-purpose facilities, complexity of service product, etc. Nevertheless, not much seem to have been done in improving estimation methodology of the cost of network facilities. As a result, the quality of cost information on network facilities has deteriorated, and now even decision-makers in the industry dismiss the information. Recently, two major telecommunication companies adopted a new network cost estimation method to deal with the issue. In this paper, we study the concept of new cost estimation method and the procedure to develop and apply it. We also suggest the method to carry out the cost allocation using Matlab which is more efficient and time-saving than other commercial cost calculation packages.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 2006년도 추계학술대회
• /
• pp.332-335
• /
• 2006

This paper considers a facility location problem, which is concerned with locating facilities on a supply chain network and installing the associated equipments at the facilities to meet a given set of demands. The objective function is to minimize the sum of setup cost (facility opening cost and equipment installation cost), operation cost, and distribution cost. For the equipments, various choices of equipment modes need to be determined. Moreover, in the problem, overwork is allowed each facility but at expensive operation cost. The proposed problem is characterized as being NP-hard problem, so that a heuristic algorithm is derived. In order to evaluate the performance of the proposed algorithm, computational experiments with various numerical instances are conducted.

• 경영과학
• /
• 제27권3호
• /
• pp.1-14
• /
• 2010

In this paper we study the access network design problem in Universal Mobile Telecommunication Systems (UMTS) networks. Given the location of radio base stations (node-Bs), their traffic demands, and the candidate facility centers for locating radio network controllers (RNCs), the problem is to determine the configuration of access network, including the number and location of facility centers, the number of RNCs in each facility center, and the links between RNCs and node-Bs, with the objective being to design such a network at the minimum cost. We provide a mathematical formulation of the problem with constraints on RNC and node-B capacities, along with a lower bounding method. We develop a heuristic algorithm with two different initial solution methods designed to strengthen the solution quality. The computational efficacy of their procedures is then demonstrated on a number of test problems.

• 한국건설관리학회논문집
• /
• 제7권4호
• /
• pp.91-99
• /
• 2006

본 연구는 신축 교육시설 프로젝트의 개념단계에서 공사비를 예측하기 위한 인공신경망모델의 제안을 목적으로 한다. 현행 공공 교육시설의 개념단계 공사비예측에는 기본인자인 연면적에 의한 단일변수 모델이 적용되고 있다. 그러나 개념단계에서 단일변수 공사비예측모델을 적용하여 예측된 공사비는 그 오차범위가 크고, 실시설계 완료 후 물량산출에 의해 산정된 상세공사비와 비교하여 큰 차이를 보일 경우 프로젝트의 수정이 불가피하며, 이는 프로젝트의 비용을 증가시키고 공기를 지연시킨다. 그러므로 본 연구에서는 교육시설 프로젝트의 사업계획 수립 및 예산확보 과정에서 공사비예측에 적용이 가능한다 변수 인공신경망모델을 제안하였다. 개발된 모델을 평가한 결과 평균오차율이 6.82%로써, 평균 93.18%의 정확도를 기록하였다. 제안된 인공신경망모델은 지난 5년간 신축된 교육시설의 공사예정금액을 실적자료로 사용하여 학습되었기 때문에, 차후 교육시설 신축공사의 예산편성에 그 활용이 기대된다.

• 한국경영과학회지
• /
• 제29권1호
• /
• pp.57-70
• /
• 2004

Given a tree network on which each node has its own demand and also stands for a candidate location of a potential facility. such as plant or warehouse, the f-median problem on the network (PMPOT) is to select less than or equal to P number of facility locations so that the whole demand on a node is satisfied from only one facility and the total demand occurred on the network can be satisfied from those facilities with the minimum total cost, where the total cost Is the sum of transportation costs and the fixed costs of establishing facilities. Tamir(1996) developed an O(p n$^2$) algorithm for PMPOT which is known to be the best algorithm In terms of the time complexity, where n is the number of nodes in the network, but he didn't make any comments or explanation about implementation details for finding the optimal solution. In contrast to Tamir's work, Kariv and Hakimi(1979) developed O(p$^2$n$^2$) algorithm for PMPOT and presented O(n$^2$) algorithm for finding the optimal solution in detail. In this paper, we not only develop another O(p n$^2$) dynamic programming algorithm for PMPOT that is competitive to Tamir's algorithm in terms of the time complexity, but also present O(n) algorithm that is more efficient than kariv and Hakimi's algorithm in finding the optimal solution. finally, we implement our algorithm on a set of randomly generated problems and report the computational results.

• Industrial Engineering and Management Systems
• /
• 제15권4호
• /
• pp.374-384
• /
• 2016

The efficiency of a supply chain can be extremely affected by its design which includes determining the flow pattern of material from suppliers to costumers, selecting the suppliers, and defining the opened facilities in network. In this paper, a multi-objective multi-echelon multi-product supply chain design model is proposed in which several suppliers, several manufacturers, several distribution centers as different stages of supply chain cooperate with each other to satisfy various costumers' demands. The multi-objectives of this model which considered simultaneously are 1-minimize the total cost of supply chain including production cost, transportation cost, shortage cost, and costs of opening a facility, 2-minimize the transportation time from suppliers to costumers, and 3-maximize the service level of the system by minimizing the maximum level of shortages. To configure this model a graph theoretic approach is used by considering channels among each two facilities as links and each facility as the nodes in this configuration. Based on complexity of the proposed model a multi-objective Pareto-based vibration damping optimization (VDO) algorithm is applied to solve the model and finally non-dominated sorting genetic algorithm (NSGA-II) is also applied to evaluate the performance of MOVDO. The results indicated the effectiveness of the proposed MOVDO to solve the model.

• 산업공학
• /
• 제14권1호
• /
• pp.30-38
• /
• 2001

Logistics network management has become one of the most important sources of competitive advantage regarding logistics cost and customer service in numerous business segments. Logistics network simulation is a powerful analysis method for designing and planning the logistics network optimally in an integrated way. This paper introduces a logistics network simulator, LONSIM, developed by author. LONSIM deploys a mix of simulation and optimization functions to model and analysis logistics network issues such as facility location, inventory policy, manufacturing policy, transportation mode, warehouse assignment, supplier assignment, order processing priority rule, and vehicle routes. LONSIM is built with AweSim 2.1 and Visual Basic 6.0, and executed in windows environment.

• ETRI Journal
• /
• 제30권4호
• /
• pp.587-596
• /
• 2008

Facility-based competition (FBC) in the telecommunications market is considered to have lower static efficiency in the short term and higher dynamic efficiency in the long term. Under service-based competition (SBC), the entrant can reduce its setup costs by leasing network facilities from the incumbent, which makes the entrant viable, pushes the market price down and promotes static efficiency. This paper attempts to measure static efficiency by comparing the profits of the incumbent and entrant in terms of consumer surplus and social welfare under each competition type by extending the Stackelberg model. The results, assuming a linear demand function and variation in regulatory level, show that FBC results in higher social welfare than SBC on the whole. However, SBC accompanied by strong regulation is also shown to have the potential to be superior over FBC. It is also revealed that FBC exhibits a higher producer surplus (particularly, the incumbent's producer surplus) and is, therefore, more desirable in terms of dynamic efficiency. When the entrant's cost is high in FBC, social welfare is shown to be lowered, implying that cost competitiveness is a necessary condition for social welfare.

• 한국콘텐츠학회논문지
• /
• 제18권8호
• /
• pp.102-108
• /
• 2018

비 보안영역의 외부인터넷과 보안영역의 내부업무망간에 적용된 기존의 망간 자료전송기술을 빌딩시설관리 SCADA시스템 제어망에 그대로 적용할 경우에 다양한 문제들이 도출된다. 기존의 망간 자료전송기술은 모든 데이터를 대상으로 블랙리스트 기반의 보안기법이 적용되기 때문에 고 복잡성 및 고 비용이 수반된다. 하지만, 빌딩시설관리 SCADA제어시스템에서 유통되는 데이터의 특성은 소수의 정형적인 제어 데이터가 반복성과 주기성을 갖기 때문에 이를 대상으로 화이트리스트 기반의 보안기법 적용이 가능하다. 이를 통해서 망간 자료전송에 적용된 보안기술이 단순화되어 저 비용으로 빌딩시설관리 SCADA시스템 제어망 구축이 가능하다. 본 논문에서는 이러한 문제점들을 정리하고 이를 해결하는 방안을 제시하여 빌딩시설관리 SCADA제어시스템에 특화된 빌딩 제어망 구축방안을 제안하였다.