• 한국국방경영분석학회지
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• 제6권2호
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• pp.47-67
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• 1980

Interactions of major activities participating in fleet operations are investigated in the framework of a closed queueing network system with finite aircrafts assigned to it. An implementable algorithm is developed, which is useful for computing the distributions needed to evaluate the effects of the interactions on the fleet operations. The availability management program is focused on seeking an optimal resource allocation to multiple repair-shops to maximize the fleet availability subject to the budget constraint.

• 한국항해학회지
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• 제23권4호
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• pp.63-76
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• 1999

This paper aims at developing an integrated fleet management support system for industrial carriers who usually control the vessels of their own or on a time charter to minimize the cost of shipping their cargoes. The work is mainly concerned with the operational management problem of the fleet owned by a major oil company, a typical industrial carrier. The optimal fleet management problem for the major oil company can be divided into two phase problem. The front end corresponds to the production operation problem of the transportation of crude oil, the refinery operation, and the distribution of product oil to comply with the demand of the market. The back end is to tackle the fleet scheduling problem to meet the seaborne transportation demand derived from the front end. Relevant optimization models for each phase are proposed and described briefly. Then a user-friendly integrated fleet management support system is built based on the proposed optimization models for both ends under Windows environment. A case study reflecting the practices of fleet management problem for the major oil company is carried out by using the system.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.223-224
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• 2023

Optimal fleet management in the planning stage is one of the most critical activities that guarantee successful construction projects. In South Korea, the construction standard production rate database (CSPRD) is normally employed. However, when it comes to a trade-off problem that involves decision-making on optimal sets of equipment to perform a certain task, the method will require the planners' in-depth knowledge and experience regarding the target process and a time consuming estimation of the performance of every possible scenario must be conducted for the deduction of the optimal fleet management. On this account, this research paper proposes a lightweight method of using mixed integer nonlinear programming (MINLP) in multi-objective problems based on CSPRD-based mathematical equations to assist planners in the preplanning stage of choosing the optimal sets of types and size machinery to efficiently arrange the construction scheduling and budgeting.

• 로봇학회논문지
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• 제17권4호
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• pp.407-416
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• 2022

Multiple AMRs have been proved to be effective in improving warehouse productivity by eliminating workers' wasteful walking time. Although Multi-agent Path Finding (MAPF)-based solution is an optimal approach for this task, its deployment in practice is challenging mainly due to its imperfect plan-execution capabilities and insufficient computing resources for high-density environments. In this paper, we present a MAPF-based fleet management system architecture that robustly manages multiple robots by re-computing their paths whenever it is necessary. To achieve this, we defined four events that trigger our MAPF solver framework to generate new paths. These paths are then delivered to each AMR through ROS2 message topic. We also optimized a graph structure that effectively captures spatial information of the warehouse. By using this graph structure we can reduce computational burden while keeping its rescheduling functionality. With proposed MAPF-based fleet management system, we can control AMRs without collision or deadlock. We applied our fleet management system to the real logistics warehouse with 10 AMRs and observed that it works without a problem. We also present the usage statistic of adopting AMRs with proposed fleet management system to the warehouse. We show that it is useful over 25% of daily working time.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.537-539
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• 2015

considerate operation is a major issue in the equipment-intensive operation. Identifying an optimal equipment combination is important to achieve low-energy operations. An Earthwork operation planning system, which measures the energy consumption of construction operations by taking into account construction equipments' engineering attributes (e.g., weight, capacity, energy consumption rate, etc.) and operation conditions (e.g., road condition, attributes of materials to be moved, geometric information, etc.), is essential to achieve the low-energy consumption. This study develops an automated computerized system which identifies an optimal earthmoving equipment fleet minimizing the energy consumption. The system imports a standard template of earthmoving operation model and compares numerous scenarios using alternative equipment allocation plans. It finds the fleet that minimizes the energy consumption by enumerating all cases using sensitivity analysis. A case study is presented to verify the validity of the system.

• 대한토목학회논문집
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• 제35권2호
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• pp.501-514
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• 2015

토공작업은 모든 종류의 토목공사에 기본이 되는 공종으로 공기, 공사비와 생산성에 영향을 미치는 요소이다. 토공은 그룹으로 형성된 다수의 건설장비들이 필요한 기계화 작업이며 건설장비로 인하여 많은 연료를 소비하는 작업이다. 그러나 일반적으로 토공작업은 건설장비 운전자의 경험과 직관에 의하여 수행되기 때문에 낮은 생산성, 높은 연료사용량 및 탄소를 많이 배출시킬 수 있는 문제점을 갖고 있다. 최근 연구에 의하면 이러한 문제점의 해결책의 하나로 건설장비 플릿관리 시스템이 제안되고 있다. 건설장비 플릿관리 시스템은 효과적인 토공계획, 최적의 건설장비 할당, 효율적인 건설장비 운영, 빠른 정보교환 등과 같은 기능을 수행한다. 본 연구에서는 건설장비 플릿관리 시스템 구축시 필요한 주요 방법론을 제시하는 것을 목적으로 하고 있다. 토공작업을 위한 3D 솔리드 파라메트릭 모델 형성, 옥트리를 이용한 토량배분, 건설장비 플릿구성 및 운영 방법론을 제시하였다. 건설장비 플릿관리 시스템의 효용성을 건설장비 가동률, 연료사용량, 이산화탄소 배출량 측면에서 검증해 보기 위하여 시뮬레이션을 실시하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.317-320
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• 2005

The LBS (Location-Based Services) are valuable information services combined the location of moving object with various contents such as map, POI (point of Interest), route and so on. The must general service of LBS is route determination service and its applicable parts are FMS (Fleet Management System), travel advisory system and mobile navigation system. The core function of route determination service is determination of optimal route from source to destination in various environments. The MODB (Moving Object Database) system, core part of LBS composition systems, is able to manage current or past location information of moving object and massive trajectory information stored in MODB is value-added data in CRM, ERP and data mining part. Also this past trajectory information can be helpful to determine optimal route. In this paper, we suggest methods to determine optimal route by querying past trajectory information in MODB system and verify the effectiveness of suggested method.

• 수산해양교육연구
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• 제29권2호
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• pp.503-512
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• 2017

Over the past few years, as maritime trade and traffic were highly expanding, problem of invasive species via ballast water have been raised. In 1988, Canada and Australia had firstly experience that unexpected and hazardous species were observed on their own sea, they have issued the problem to MEPC under the IMO. At the end of many years of discussion, on the diplomatic conference in 13 Feb. 2004, "International Convention for the Control and Management of Ballast Water and Sediments of the Ship" was adopted. Requirements for entering into force of this Convention is that 30 countries ratify and world merchant marine fleet is more than 35% and BWM Convention will be effected after 12months from date satisfying conditions. With Finland ratifying the BWM Convention on 8 Sep. 2016, the fleet amounted to 35.1441% and ratification country became 52 countries. Therefore, after 12month, BWM Convention will be formally effected on 8 Sep. 2017. Ballast Water Treatment System is to be fitted in new ships as well as existing ships. Thus, there are concerns of ship owners to be suitably installed a variety typed BWTS in many kinds of vessels. As approaching for resolving these problems, engineering analysis was carried out research studies and detailed design to analyze to optimal installation space for retrofitting a BWTS using 3D Scanning method, targeting representative DWT 180K Bulk carrier of dry cargo vessels charged more 40% on worldwide vessel and mainly two type BWTS as electrolysis treatment type and ultra violet treatment type. Optimal design of 3D Scanning technology was applied to analyze four step process and the overall conclusion was described in this paper.

• Management Science and Financial Engineering
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• 제17권2호
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• pp.1-21
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• 2011

This paper considers an integrated inventory-distribution system with a fleet of heterogeneous vehicles employed where a single warehouse distributes a single type of products to many spatially distributed retailers to satisfy their dynamic demands. The problem is to determine order planning at the warehouse, and also vehicle schedules and delivery quantities for the retailers with the objective of minimizing the sum of ordering cost at the warehouse, inventory holding cost at both the warehouse and retailers, and transportation cost. For the problem, we give a Mixed Integer Programming formulation and develop a Lagrangean heuristic procedure for computing lower and upper bounds on the optimal solution value. The Lagrangean dual problem of finding the best Lagrangrean lower bound is solved by subgradient optimization. Computational experiments on randomly generated test problems showed that the suggested algorithm gives relatively good solutions in a reasonable amount of computation time.

• 대한교통학회지
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• 제22권7호
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• pp.107-117
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• 2004

특송 소화물 수송은 상품의 생산과 소비에 직결되어 있으며 소비자에 대한 원활한 소화물 수송이 경제에 미치는 영향이 지대하므로 그 중요성은 날로 증대하고 있다. 특히, 소비자 중심의 다 빈도 소량 운송시대로의 전환과 택배 등 특송 소화물 운송 산업의 활성화에 대한 화물수송 증가추세에 비해 적절한 계획 및 정책이 결여되어 있는 실정이다. 본 논문에서는 물류센터(단지)에서 모든 고객에게 수 배송을 가장 빠른 시간 내에 완료하여 고객이 서비스를 받기 위해 대기하는 시간을 최소화하는 차량경로를 결정하는 배송완료시간 최소화를 위한 차량경로모형을 제시한다. 본 연구에서는 마지막으로 방문을 받는 수요자의 대기시간을 최소화하는 개념으로서 생산문제와 비교하면 단위시간당 동일한 비용이 지출된다고 가정 할 때 모든 제품의 생산 및 판매까지의 총 비용을 최소화하는 것이 고전적인 차량경로문제라고 본다면 모든 제품의 생산완료 시점을 최소화하여 납기일을 단축시키는 것이 특징으로 볼 수 있다. 본 수리모형이 고전적인 차량경로문제와 구별되는 개념 중 하나는 각 차량의 마지막 방문수요지에서 물류센터로 복귀하는 시간은 고려하지 않으며 이에 따라 동일한 수요자를 방문하더라도 방문순서에 따라서 이동시간이 상이한 것과 또한 차량들이 방문하는 총 이동시간이 동일하더라도 경로 변경에 따라 모든 수요자 중 가장 마지막에 방문을 받는 수요자의 대기시간을 단축할 수 있다. 일반적으로 이러한 모형은 배송을 완료하는 시점이 중요시 되는 특송 소화물, 신문배송 문제, 신선함을 요하는 상품 또는 퀵 서비스 등 다양한 서비스 문제에 확대 적용할 수 있다. 제시된 모형은 ILOG Cplex 및 Solver를 활용하여 기존 차량경로문제와 비교하여 다양한 고객 및 차량 수에 대하여 최적해에 근접한 해를 쉽게 구할 수 있다.