Seung Yeob Lee

So Rim Han

Tae Hoon Lee

Byeoung Chul Lee

Young Tae Ryu

Ho Young Jeong

Jung Won Park

✔️본 연구실은 다양한 공학적, 사회과학적 시스템의 문제를 해결하고 최적의 의사결정을 내리기 위한 연구를 진행합니다.
✔️본 연구실
은 최적화 분야에 관심 있는 모든 분들에게 열려 있습니다.
Mathematical optimization models & solution algorithms (heuristic)
Development of artificial intelligence algorithms
Deriving quantitative decisions
Insight & optimal decision-making for management and operational issues
Engineering problem definition
Implementing virtual environments through simulation
Production & In-Factory Logistics
Robotics Delivery Service
Sustainable Remanufacturing & Reverse Logistics
Other Social Science Topics

본 연구실은 다양한 공학적, 사회과학적 시스템의 문제를 해결하고 최적의 의사결정을 내리기 위한 연구를 진행합니다. 본 연구실은 최적화 분야에 관심 있는 모든 분들에게 열려 있습니다. Mathematical optimization models & solution algorithms (heuristic) Development of artificial intelligence algorithms Deriving quantitative decisions Insight & optimal decision-making for management and operational issues Engineering problem definition Implementing virtual environments through simulation Production & In-Factory Logistics Robotics Delivery Service Sustainable Remanufacturing & Reverse Logistics Other Social Science Topics

Rolling horizon optimization of urban air mobility (UAM) service with shared riding, vertiport-airspace capacity, and recharge: a mathematical model and efficient heuristic

Meta-learning-based adaptive operator selection for traveling salesman problem

Optimization of urban logistics with multi-modal systems: A comprehensive study of the airship-vehicle routing problem

Optimizing Urban Logistics: Vehicle Routing Problem With Underground Transportation

A 3-Dimensional Cargo Loading Algorithm for the Conveyor-Type Loading System

Optimization of OmniChannel Distribution Network Using Micro Fulfillment Center Under Demand Uncertainty

The UAM sevice network: multi-objective and multi-period design for UAM airports

Optimal operation scheduling of mobile hydrogen charging stations: A mathematical optimization model and heuristic approach

Optimal scheduling and quantitative analysis for multi-flying warehouse scheduling problem: Amazon airborne fulfillment center

Toward Flexible and Persistent UAV Service: Multi-Period and Multi-Objective System Design with Task Assignment for Disaster Management

Simultaneous Cooperation of Refrigerated Ground Vehicle (RGV) and Unmanned Aerial Vehicle (UAV) for Rapid Delivery with Perishable Food

Redesign of reverse logistics network with managerial decisions on the minimum quality level and remanufacturing policy

Application of UAVs for tourism security and safety

Efficient food service chain management considering substitute products

The Flying Warehouse Delivery System: A Quantitative Approach for the Optimal Operation Policy of Airborne Fulfillment Center

Creative service design for airline's extra revenue

Truck-drone hybrid delivery routing: Payload-energy dependency and no-fly zones

Sustainable service design and revenue management for electric tour bus systems: Seoul city tour bus service and the eco-mileage program

A bi-objective network design for value recovery of neodymium-iron-boron magnets: A case study of the United States

Genetic Algorithm Based Rail Design Optimization for OHT Systems with Machine Learning Performance Prediction

A Scalable and Robust Optimization Algorithm for an Intermodal Ground-Underground-Aerial Logistics System

A UAM Routing and vertiport pad assignment : A mathematical optimization model and case study

지하물류 시스템을 통합한 다층 도심 물류 네트워크 최적화 : 차량 및 드론 경로 문제 접근

고객 픽업 기반의 지하 물류 배송 및 재고 관리 최적화

Genetic Algorithm을 활용한 반도체 OHT Rail 설계 최적화 연구

Optimization of Collaborative Truck-Drone-Subway Delivery for Urban Logistics

Transportation Mode Selection for Middle Mile Delivery: Robust Optimzization and Analysis

Flying Warehouse Delivery System with Multi-commodity Inventory Management

Optimal Operation and Effectiveness of Sustainable Eco-friendly Last Mile Delivery

Optimal Operation Scheduling of Mobile Hydrogen Charging Station for Expansion of Hydrogen Charging Infrastructure

Sharable Battery-Exchange Station for Eco-Friendly Last Mile Delivery Vehicles: Multi- Period and Multi-Objective Location Optimization with Connectivity

Simultaneous Cooperation of Refrigerated Vehicle and UAV: Route Optimization for Early Morning Delivery Service

A Study on the Vehicle Routing Problem for Repositioning Shared Micro Mobility to Improve Service Profitability

Movable Unmanned Aerial System: Optimization of System, Resource Design and Drone Routing

Truck-drone hybrid delivery routing: Payload-energy dependency and No-Fly zones

Persistent UAV delivery logistics: MILP formulation and efficient heuristic

A vehicle routing problem of both refrigerated-and general-type vehicles for perishable food products delivery

On the scheduling of systems of UAVs and fuel service stations for long-term mission fulfillment

Persistent UAV service: An improved scheduling formulation and prototypes of system components

Rolling horizon path planning of an autonomous system of UAVs for persistent cooperative service: MILP formulation and efficient heuristics

Mathematical investigation on the sustainability of UAV logistics

The flying warehouse delivery system: A quantitative approach for the optimal operation policy of airborne fulfillment center

Efficient location and allocation strategies for undesirable facilities considering their fundamental properties

Simultaneous cooperation of Refrigerated Ground Vehicle (RGV) and Unmanned Aerial Vehicle (UAV) for rapid delivery with perishable food

Toward flexible and persistent UAV service: Multi-period and multi-objective system design with task assignment for disaster management

Quantitative approaches for location decision strategies of a hotel chain network

Location, capacity and capability design of emergency medical centers with multiple emergency diseases

Sustainable value recovery of NdFeB magnets: a multi-objective network design and genetic algorithm

Quantitative approaches for economic use of emerging technology in the tourism industry: unmanned aerial vehicle systems

Byung Duk Song

The truck-drone hybrid delivery system uses a truck as a station for drones in addition to its delivery function and is getting attention because the strengths of these individual vehicles can be selectively and synergistically exploited. In this study, we extended the previous vehicle routing models to the hybrid delivery systems by taking into account two important practical issues: the effect of parcel weight on drone energy consumption and restricted flying areas. The flight range of the drones is heavily susceptible to the loaded weight due to the limited battery life. Drones are also not allowed to fly over sensitive facilities regulated by the Federal Aviation Administration (FAA) or temporarily in certain areas due to weather-related conditions. We developed a mathematical model that incorporates these issues and propose a two-phase constructive and search heuristic algorithm to provide computational efficiency of the …

The high efficiency, flexibility and low cost of Unmanned Aerial Vehicles (UAVs) present huge application opportunities in various industries. Among those various applications, we focus herein on the use of UAVs in delivery logistics. The UAV logistics system has some fundamental characteristics that distinguish it from the usual ground logistics such as limited flight time, loadable capacity, effect of cargo weight on flight ability, and others. To handle the above issues, we propose a Mixed Integer Linear Programming (MILP) formulation for derivation of persistent UAV delivery schedules. To address the computational issues, a Receding Horizon Task Assignment (RHTA) heuristic is developed and tested with numerical examples for island-area delivery.

This study examines a vehicle routing problem that encompasses both refrigerated- and general-type of vehicles for multi-commodity perishable food products delivery. It is assumed that both the location and the volume of the ordered food products for each customer are known. Furthermore, the capacity, maximum delivery time, and available number of both refrigerated- and general-type of vehicles are predetermined. By reflecting these characteristics, we develop a nonlinear mathematical model and a heuristic algorithm to generate efficient vehicle routings with the objective of maximizing the total level of the customer satisfaction which is dependent on the freshness of delivered food products. In addition, numerical examples and sensitivity analysis are provided to show the validity of the model. The aim of this study is to confirm the performance and the availability of refrigerated-type vehicle for perishable food …

The duration of missions that can be accomplished by a system of unmanned aerial vehicles (UAVs) is limited by the battery or fuel capacity of its constituent UAVs. However, a system of UAVs that is supported by automated refueling stations may support long term or even indefinite duration missions. We develop a mixed integer linear program (MILP) model to formalize the problem of scheduling a system of UAVs and multiple shared bases in disparate geographic locations. There are mission trajectories that must be followed by at least one UAV. A UAV may hand off the mission to another in order to return to base for fuel. To address the computational complexity of the MILP formulation, we develop a genetic algorithm to find feasible solutions when a state-of-the-art solver such as CPLEX cannot. In practice, the approach allows for a long-term mission to receive uninterrupted UAV service by successively handing …

The flight duration of unmanned aerial vehicles (UAVs) is limited by their battery or fuel capacity. As a consequence, the duration of missions that can be pursued by UAVs without supporting logistics is restricted. However, a system of UAVs that is supported by automated logistics structures, such as fuel service stations and orchestration algorithms, may pursue missions of conceivably indefinite duration. This may be accomplished by handing off the mission tasks to fully fueled replacement UAVs when the current fleet grows weary. The drained UAVs then seek replenishment from nearby logistics support facilities. To support the vision of a persistent fleet of UAVs pursuing missions across a field of operations, we develop an improved mixed integer linear programming (MILP) model that can serve to support the system’s efforts to orchestrate the operations of numerous UAVs, missions and logistics facilities. Further …

A networked system consisting of unmanned aerial vehicles (UAVs), automated logistic service stations (LSSs), customer interface software, system orchestration algorithms and UAV control software can be exploited to provide persistent service to its customers. With efficient algorithms for UAV task planning, the UAVs can autonomously serve the customers in real time. Nearly uninterrupted customer service may be accomplished via the cooperative hand-off of customer tasks from weary UAVs to ones that have recently been replenished at an LSS. With the goal of enabling the autonomy of the task planning tasks, we develop a mixed integer linear programming (MILP) formulation for the problem of providing simultaneous. UAV escort service to multiple customers across a field of operations with multiple sharable LSSs. This MILP model provides a formal representation of our problem and enables use in a rolling …

Unmanned aerial vehicles (UAVs) are expected to make groundbreaking changes in the logistics industry. Leading logistics companies have been developing and testing their usage of UAVs recently as an environmentally friendly and cost-effective option. In this paper, we investigate how much the UAV delivery service is environmentally friendly compared to the traditional ground vehicle (GV) delivery service. Since there are fuel (battery) and loadable weight restrictions in the UAV delivery, multi-hopping of UAV is necessary, which may cause a large consumption of electrical energy. We present a two-phase approach. In Phase I, a new vehicle routing model to obtain optimal delivery schedules for both UAV-alone and GV-alone delivery systems is proposed, which considers each system’s restrictions, such as the max loadable weight and fuel replenishment. In Phase II, CO 2 emissions are computed as a sustainability measure based on the travelling distance of the optimal route obtained from Phase I, along with various GV travel-speeds. A case study finds that the UAV-alone delivery system is much more CO 2 efficient in all ranges of the GV speeds investigated.

Purpose In the tourism industry, unmanned aerial vehicles (UAVs) can perform monitoring and patrol missions to protect assets and tourists at attractions such as coastal areas, canyons, national parks, etc. Such use of UAVs can improve safety and security of tourism attraction and facilitate tourism industry. However, there is a key issue regarding economic investment and efficient operation for actual system implementation. The purpose of this paper is to provide a guideline for supporting economic investment and the efficient operation of UAV system in the tourism industry. Design/methodology/approach Ideas and methodologies have been proposed to overcome the fundamental limitations of commercial UAVs. A mathematical optimization model is developed to determine the optimal number of UAVs to be purchased, and its operation schedules simultaneously …

In April 2016, Amazon won a patent for a flying warehouse that deploys unmanned aerial vehicles (UAVs) to deliver parcels to customers. In this system, the airborne fulfillment center (AFC) remains or moves at a high altitude, and UAVs are deployed from the AFC to deliver orders to customers. Smaller airships, also known as shuttles, may be used to replenish the AFC with inventory, UAVs, fuel, supplies, and staff. Amazon’s AFC delivery system is a novel and challenging system that can convert same-day deliveries into 10 min deliveries and provide a wide range of UAV delivery services for Amazon Prime members. However, to operate the AFC delivery system efficiently, a quantitative operation methodology needs to be developed, which considers the related regulations and consumable replenishment. In this study, mixed-integer linear programming is developed to derive optimal operation schedules for AFC …

The phrase “not in my backyard” (NIMBY) refers to the well-known social phenomena in which residents oppose the construction or location of undesirable facilities near their homes. Examples of such facilities include electric transmission lines, recycling centers and crematoria. Due to the opposition typically encountered in constructing an undesirable facility, the facility planner should understand the nature of the NIMBY phenomena and consider it as a key factor in determining facility location. We examine the characteristics of NIMBY phenomena and suggest two alternative mathematical optimization models with the objective of minimizing the total degree of NIMBY sentiments. Genetic algorithms are proposed to solve our linear and nonlinear integer programs. The results obtained via genetic algorithms for our linear integer programs are compared with those of CPLEX to evaluate their performance. The …

With the growth of e-commerce, various types of last-mile delivery services have emerged to meet customer needs. Among the most notable of these are “rapid delivery” and “perishable food delivery” services. Owing to their advantages, the use of unmanned aerial vehicles (UAVs), which are both fast and inexpensive, has received considerable interest for rapid delivery. However, because of the inherent limitations of UAVs, they are used in conjunction with other ground vehicles. In contrast, maintaining freshness during delivery of perishable food is crucial for customer satisfaction and hygiene. Consequently, the cooperative operation of refrigerated ground vehicles (RGVs) with UAVs is necessary for rapid and fresh delivery services. RGVs can focus on the delivery of perishable foods and large-sized general products in such an operation, whereas UAVs can focus on small-sized general goods. In this study, the …

Rare earth elements (REEs) such as neodymium (Nd) and dysprosium (Dy) are indispensable in modern society because they are vital for creating powerful neodymium-iron-boron (NdFeB) magnets used in many technological applications. These elements have been subject to a significant supply uncertainty. A promising strategy to alleviate supply risk is value recovery from end-of-life (EOL) products. This paper proposes a reverse supply network to optimize: 1) the locations and capacities of dismantling and recycling facilities, and 2) the transportation flows between collection centers, dismantling facilities, recycling facilities, and sales points. Two objectives are considered: maximizing profit and environmental benefits. A Pareto front is created that shows non-dominated optimal solutions. When the model was applied to the United States, California was found to be the most important state for EOL product …

Usability of lightweight unmanned aerial vehicles (UAVs) limited in a variety of activities in disaster management due to two fundamental drawbacks: limited flight duration, and limited loading capacity. With the proper system design and task assignment methodologies, these limitations can be overcome to enable long-duration UAV missions over large areas. The present study set out to determine the optimal unmanned aerial system (UAS) system design and UAV task assignment for such applications. Based on a proposed multi-objective mathematical model, exact Pareto optimal solutions were derived using the ε–constraint method. To find approximate Pareto solutions, an approximate two-phase (ATP) approach was developed, which is computationally inexpensive compare to the optimal solution approach. Through numerical experiments based on a realistic case study, it was shown that the ATP approach …

Accommodation revenue and demand are affected by hotel location, leading a lot of research to perform theoretical, empirical and operational approaches to analyze and determine the ideal location of hotels. However, operational approaches such as mathematical modeling based optimization have not received sufficient interest in hotel location research while it has been widely used for various kinds of facility locations. Therefore, two mathematical models for opening of new hotels and the closing of existing hotels to a manage hotel chain network are developed using the demand estimation and existing hotel information. In this research, hotel demand is estimated based on the accessibilities to sightseeing, transportation, business points, and market share. Gaining and/or losing of demand and the agglomeration effect are introduced as the objective of two models. Proposed mathematical models are tested to …

This paper studies the location, allocation and capacity design of emergency medical centers (EMC) in a given region under the closest assignment rule. It is assumed that for each EMC candidate center the capability and initial capacity on each category of treatable medical diseases are provided. Selected medical center receives a prescribed amount of subsidies from the government in return for the offering of medical services at a competitive cost. It is further assumed that with additional subsidies EMC candidate center can not only enlarge its capacities for treatable medical diseases but also newly begin medical treatment for the diseases not included in the original capability. The number of patients of each patient group node during a unit time is assumed to be known along with the categories of their diseases. The problem is formulated as an integer program (IP) with the objective of minimizing the total …

Neodymium–iron–boron (NdFeB) magnets are widely used in clean energy applications such as wind turbines and electric vehicles whose demand is escalating. However, rare earth elements (REEs) for manufacturing NdFeB magnets are subject to significant supply uncertainty due to Chinese near-monopolistic supply. To mitigate the risk, companies are actively pursuing value recovery from end-of-life magnets. However, the questions of how to collect used magnets and smoothly transfer them through the reverse supply chain require further investigation. To address this challenge, this paper designs an efficient NdFeB magnet recovery infrastructure by identifying the optimal processing facility locations and defining the capacities and transportation flows that maximize the economic and environmental benefits and social support for the new business. Mathematical model and a m ulti- o bjective n etwork d esign g …

The outstanding advantages of unmanned aerial vehicles (UAVs) have led to an intensive study of the UAV system over the past decade. A variety of potential UAV applications are emerging nowadays, and UAV delivery is one in the limelight. However, one of the critical issues for UAV delivery service is how UAVs can be persistently used within their fundamental limited battery capacity. One recent approach to alleviate the weaknesses is using a cooperative system of UAVs with movable stations for the delivery logistics. The movable stations move across the field of operation, providing persistent delivery service using UAVs by efficiently replenishing the consumables of UAVs. In this study, one of the compelling cooperative delivery services called the flying warehouse system is investigated. The concept of the flying warehouse delivery service has firstly filed as a patent by the e-commerce giant Amazon. The …

In reverse logistic networks, end-of-use products are collected and transported to the factory for remanufacturing. The economic and environmental values of a reverse network depend significantly on the quality of the end-of-use products and the remanufacturing policies. Therefore, it is desirable to consider the minimum quality level of the remanufacturing and the remanufacturing policy during the initial design stage. A redesign of the reverse logistics network is addressed based on decisions made regarding the location of the collection facility, the allocation, the minimum quality level and the remanufacturing policies. Based on the known continuous distribution for the quality of an end-of-use product, a bi-objective mathematical model was developed. A mathematical model was then transformed into mixed integer programmes using quadratic terms in the constraints through the development of a discretisation …

As technological innovations develop, new categories of services are emerging. In the tourism industry, one of the limelight technologies is an unmanned aerial vehicle (UAV) for virtual tourism systems, monitoring, and patrol activities for safety and security. However, for the successful application of a UAVs system, it is important to construct the system in an economic and efficient manner. In this study, quantitative approaches for a UAV system are introduced to support the economic establishment and its efficient operation. Two mathematical models are developed to construct and operate UAVs systems for recreation and safety purposes in the tourism industry. The validity of the proposed models is demonstrated via numerical experiments for both cases. To our knowledge, this is the first approach to address the issues of a UAV system design for tourism purposes. This study is expected to be the theoretical basis …

Sustainable tourism has true sustainability when it is designed economically and in an environmentally friendly fashion. A variety of methods has been explored to achieve sustainable tourism, and the use of new technologies is a significant trend for sustainable tourism. In the City Tour Bus service, an environmentally friendly tour service can be achieved by using electric buses. Moreover, the social energy saving program helps to reduce the economic burden of building eco-friendly services by providing economic incentives as rewards for environmental contributions. Two mathematical models are newly developed to quantitatively design and operate a sustainable City Tour Bus service. Mathematical model I is developed with two objective functions of minimizing total investment cost and CO 2 emissions. It derives from Pareto solutions with different number of electric buses and battery capacities. Based on the …

System Analytics & Optimization Lab

교수님 소개

송병덕

연구실 소개

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Genetic Algorithm Based Rail Design Optimization for OHT Systems with Machine Learning Performance Prediction

A Scalable and Robust Optimization Algorithm for an Intermodal Ground-Underground-Aerial Logistics System

Rolling horizon optimization of urban air mobility (UAM) service with shared riding, vertiport-airspace capacity, and recharge: a mathematical model and efficient heuristic

연구실 보유 특허

대학별 입시끈

우리 연구실 모집

교수님 소개

송병덕

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Genetic Algorithm Based Rail Design Optimization for OHT Systems with Machine Learning Performance Prediction

A Scalable and Robust Optimization Algorithm for an Intermodal Ground-Underground-Aerial Logistics System

Rolling horizon optimization of urban air mobility (UAM) service with shared riding, vertiport-airspace capacity, and recharge: a mathematical model and efficient heuristic

연구실 보유 특허

최근 3년간 연구실적 높은 연구실

대학별 입시끈

우리 연구실 모집