• 대한산업공학회지
• /
• 제33권2호
• /
• pp.265-272
• /
• 2007

The purpose of Vehicle Routing Problem (VRP) is to design the least costly (distance, time) routes for a fleet of identically capacitated vehicles to serve geographically scattered customers. There may be some restrictions such as the maximal capacity for each vehicle, maximal distance for each vehicle, time window to visit the specific customers, and so forth. This paper is concerned with VRP to minimize the sum of elapsed time from departure, where the elapsed time is defined as the time taken in a moving vehicle from the depot to each customer. It is important to control the time taken from departure in the delivery of perishable products or foods, whose freshness may deteriorate during the delivery time. An integer linear programming formulation is suggested and a heuristic for practical use is constructed. The heuristic is based on the set partitioning problem whose performances are compared with those of ILOG dispatcher. It is shown that the suggested heuristic gave good solutions within a short computation time by computational experiments.

• 산업융합연구
• /
• 제21권8호
• /
• pp.129-136
• /
• 2023

본 연구는 시뮬레이션기반 분만간호 실습이 간호대학생의 문제해결의 적극성, 임상수행능력, 팀효능감에 미치는 효과를 검증하기 위한 단일군 전·후 설계의 유사실험 연구이다. D시에 소재한 S대학의 간호대학생 3학년을 대상으로 시뮬레이션기반 분만간호 실습을 운영하였으며, 사전·사후 설문에 응답한 78명의 자료를 분석하였다. 자료수집은 2022년 8월 30일부터 2022년 10월 28일까지 이루어졌으며, 자료분석은 SPSS 27.0 프로그램을 사용하여 분석하였다. 연구 결과 시뮬레이션기반 분만간호 실습은 간호대학생의 문제해결의 적극성, 임상수행능력, 팀효능감에 긍정적인 효과가 있는 것으로 확인되었다. 이에 간호대학생에게 임상 현장 사례를 기반한 분만간호 시뮬레이션 교육을 적용한다면 임상에서 요구하는 핵심 능력 및 교육 만족도 향상에 긍정적인 영향을 미칠 것으로 생각된다. 그러나 연구결과를 일반화하는데 한계가 있어 충분한 표본 수의 무작위 대조군 사전·사후 연구를 통해 그 효과를 검증하고, 효과의 지속성을 장기적으로 추적 관찰할 필요가 있다.

• 대한산업공학회지
• /
• 제37권4호
• /
• pp.331-341
• /
• 2011

This paper considers an inbound lot-sizing and outbound dispatching problem for a single product in a thirdparty logistics (3PL) distribution center. Demands are dynamic and finite over the discrete time horizon, and moreover, each demand has a delivery time window which is the time interval with the dates between the earliest and the latest delivery dates All the product amounts must be delivered to the customer in the time window. Ordered products are shipped by multiple vehicle types and the freight cost is proportional to the vehicle-types and the number of vehicles used. First, we formulate a mixed integer programming model. Since it is difficult to solve the model as the size of real problem being very large, we design a conventional genetic algorithm with a local search heuristic (HGA) and an improved genetic algorithm called adaptive genetic algorithm (AGA). AGA spontaneously adjusts crossover and mutation rate depending upon the status of current population. Finally, we conduct some computational experiments to evaluate the performance of AGA with HGA.

• 대한산업공학회지
• /
• 제40권4호
• /
• pp.435-441
• /
• 2014

This paper considers a single-product problem for inbound lot-sizing and outbound dispatching at a third-party warehouse, where the demand is dynamic over the discrete time horizon. Each demand must be delivered into the corresponding delivery time window which is the time interval characterized by the earliest and latest delivery dates of the demand. Ordered products are shipped by heterogeneous container types. Each container type has type-dependent carrying capacity and the unit freight cost depends on each container type. Total freight cost is proportional to the number of each container type used. Also it is assumed that related cost functions are concave and backlogging is not allowed. The objective of the paper is to simultaneously determine the optimal inbound lot-sizing and outbound dispatching plans that minimize total costs which include ordering, shipping, and inventory holding costs. The optimal solution properties are characterized for the problem and then a dynamic programming algorithm is presented to find the optimal solution.

• 한국컴퓨터정보학회논문지
• /
• 제14권4호
• /
• pp.59-67
• /
• 2009

무선 센서 네트워크에서 위치 기반 그리디 포워딩 기법(Geographic greedy forwarding) 은 한 홉 내의 주위 노드들의 위치 정보만 가지고 데이터 전송 경로를 설정하기 때문에 자신보다 목적지에 더 가까운 노드가 존재하지 않는 경우 데이터를 전달할 수 없는 경우가 발생한다. 본 논문에서는 이러한 보이드 문제가 발생한 환경에서 데이터를 효과적으로 전송하기 위해 향상된 위치 기반 라우팅 알고리즘(CGR: Cost based Geographic Routing)을 제안한다. 제안하는 CGR 알고리즘은 그림자 경계 영역을 설정하고 설정된 영역에 존재하는 노드들끼리 비용 함수 연산 알고리즘을 통하여 효과적인 그리디 포워딩이 수행되도록 한다. 시뮬레이션 결과, 제안한 알고리즘이 기존의 알고리즘보다 평균 전체 라우팅 경로길이가 줄어들 뿐만 아니라, 데이터 전달성공 비율이 높고 에너지 절감 효과가 뛰어남을 확인하였다.

• Journal of Information Technology Applications and Management
• /
• 제26권1호
• /
• pp.53-64
• /
• 2019

The purpose of this study is to find out the fast delivery route that several drones return a truck again after departing from it for delivery locations at each cluster while the truck goes through the cluster composed of several delivery locations. The main issue is to reduce the total delivery time composed of the delivery time by relatively slow trucks via clusters and the sum of maximum delivery times by relatively fast drones in each cluster. To solve this problem, we use a three-step heuristic approach. First, we cluster the nearby delivery locations with minimal number of clusters satisfying a constraint of drone flight distance to set delivery paths for drones in each cluster. Second, we set an optimal delivery route for a truck through centers of the clusters using the TSP model. Finally, we find out the moved centers of clusters while maintaining the delivery paths for the truck and drones and satisfying the constraint of drone flight. distance in the two-dimensional region to reduce the total delivery time. In order to analyze the effect of this study model according to the change of the number of delivery locations, we developed a R-based simulation prototype and compared the relative efficiency, and performed paired t-test between TSP model and the cluster-based models. This study showed its excellence through this experimentation.

• 국제학술발표논문집
• /
• The 6th International Conference on Construction Engineering and Project Management
• /
• pp.704-705
• /
• 2015

Recent research has been ongoing for modular buildings in the country, and interest increases. However, in accordance with legal restrictions in the country with regard to Project Delivery system of Modular Building, the activation of modular buildings industry is obstructed. In Korea, in accordance with national contract law, the construction contract is apply to the project delivery system of modular buildings, and in accordance with Framework Act on the Construction Industry, The project delivery system of modular buildings has to be a separate order. The definition of separate order in contract as defined in the law is that the electric work and Communication work and digestion facility work has to be separate each contract in order to be ensured professionalism. In accordance with law, the project delivery system of modular buildings is that the contract for construction is concluded with the Owner and the Construction Contractor and the contract for goods is concluded with the construction Contractor and modular manufacturer. Due to these project delivery system, the domestic factory production rate when making a modular unit is significantly reduced compared to the rate of factory production abroad and the domestic factory production rate is estimated to 10-20%. Due to the factory production rate is also low, despite what can be done at the factory the workload in construction field increases. According to the workload in field increases, the effect of the schedule reduction can be reduced. It resolved to form a consortium with a modular manufacturer and construction companies or the contract is concluded with Owner, modular manufacturer and construction companies in each. In this paper, we propose a specific project delivery system for modular building to solve the problem of the low factory production rate and the problem of schedule reduction. Through this paper, due to the variety of project delivery system on modular buildings is expected to contribute to the activation of modular buildings.

• 대한산업공학회지
• /
• 제23권2호
• /
• pp.275-288
• /
• 1997

The container transportation problem is a kind of generalized pickup and delivery problem(GPDP), and a typical NP-hard problem of which polynomial algorithm has not yet been developed. In this problem, trucks have to transport containers from origins to destinations, while have to satisfy several restrictions such as request time, cargo closing time, driver's break time. In this paper, we present a straightforward heuristic and a user-interactive truck dispatching system which supports decision makers.

• 정보처리학회논문지C
• /
• 제8C권5호
• /
• pp.621-628
• /
• 2001

SET은 전자상거래에 있어서 가장 많이 사용되고 있는 결재 시스템 규약 중의 하나이다. 그러나 전자상거래에서 실질적인 배달이나 배달 확인과정에 대해서는 SET은 고려하고 있지 않다. 따라서 본 논문에서는 배달이나 배달 확인에 의한 지불에 대한 보안성을 좀 더 높여주는 SKP(Secure Key Protocol)를 제안한다. 그리고 Petri Nets 모델링 방법을 이용하여, SKP를 적용한 SET 모델의 적합성 여부를 증명한다.

• Journal of Communications and Networks
• /
• 제16권6호
• /
• pp.656-666
• /
• 2014

In delay tolerant networks (DTNs), delay is inevitable; thus, making better use of buffer space to maximize the packet delivery rate is more important than delay reduction. In DTNs, epidemic routing is a well-known routing protocol. However, epidemic routing is very sensitive to buffer size. Once the buffer size in nodes is insufficient, the performance of epidemic routing will be drastically reduced. In this paper, we propose a buffer scheme to optimize the performance of epidemic routing on the basis of the Lagrangian and dual problem models. By using the proposed optimal buffer scheme, the packet delivery rate in epidemic routing is considerably improved. Our simulation results show that epidemic routing with the proposed optimal buffer scheme outperforms the original epidemic routing in terms of packet delivery rate and average end-to-end delay. It is worth noting that the improved epidemic routing needs much less buffer size compared to that of the original epidemic routing for ensuring the same packet delivery rate. In particular, even though the buffer size is very small (e.g., 50), the packet delivery rate in epidemic routing with the proposed optimal buffer scheme is still 95.8%, which can satisfy general communication demand.