• Korean Management Science Review
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• v.25 no.1
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• pp.107-121
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• 2008

As to more efficiently manage the inventory in the retail supply chain and to meet the customer demand in a timely manner, vendor-managed inventory (VMI) has been widely accepted, which manages inventory in the retail supply chain via sharing information and collaborating with the retailers. Applying VMI generates vendor-managed inventory/distribution problem (VMIDP), which involves inventory management for both the vendor and the retailers, and the design of vehicle routes for delivery, to minimize the total operating cost in the supply chain. In this paper, we suggest a mixed integer programming (MIP) model to obtain the optimal solution for VMIDP in a two-echelon retail supply chain, and develop an efficient heuristic based on the operating principles of the MIP model. To evaluate the performance of the heuristic, its solution was compared with the one of the MIP model on a total of twenty seven test problems. As a result, the heuristic found optimal solutions on seven problems in a significantly reduced time, and generated a 4.3% error rate of total cost in average for all problems. The heuristic is applied to the case problem of the local famous franchise company together with GIS, showing that it is capable of providing a solution efficiently in a relatively short time even in the real world situation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.1
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• pp.29-35
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• 2004

Locomotive scheduling in railway systems experiences many difficulties because of the complex interrelations among resources, knowledge and various constraints. Artificial intelligence technology has been applied to solve these scheduling problems. These technologies have proved to be efficient in representing knowledge and rules for complex scheduling problems. In this paper, we have applied the CSP (Constraints Satisfaction Problems) programming technique, one of the AI techniques, to solve the problems associated with locomotive scheduling. This method is more effective at solving complex scheduling problems than available mathematical programming techniques. The advanced locomotive scheduling system using the CSP programming technique is realized based on the actual timetable of the Saemaul type train on the Kyong-bu line. In this paper, an overview of the CSP programming technique is described, the modeling of domain and constraints is represented and the experimental results are compared with the real-world existing schedule. It is verified that the scheduling results by CSP programming are superior to existing scheduling performed by human experts. The executing time for locomotive scheduling is remarkably reduced to within several decade seconds, something requiring several days in the case of locomotive scheduling by human experts.

• Industrial Engineering and Management Systems
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• v.12 no.2
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• pp.151-160
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• 2013

In the past decades, several algorithms based on evolutionary approaches have been proposed for solving job shop scheduling problems (JSP), which is well-known as one of the most difficult combinatorial optimization problems. Most of them have concentrated on finding optimal solutions of a single objective, i.e., makespan, or total weighted tardiness. However, real-world scheduling problems generally involve multiple objectives which must be considered simultaneously. This paper proposes an efficient particle swarm optimization based approach to find a Pareto front for multi-objective JSP. The objective is to simultaneously minimize makespan and total tardiness of jobs. The proposed algorithm employs an Elite group to store the updated non-dominated solutions found by the whole swarm and utilizes those solutions as the guidance for particle movement. A single swarm with a mixture of four groups of particles with different movement strategies is adopted to search for Pareto solutions. The performance of the proposed method is evaluated on a set of benchmark problems and compared with the results from the existing algorithms. The experimental results demonstrate that the proposed algorithm is capable of providing a set of diverse and high-quality non-dominated solutions.

• Advances in Computational Design
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• v.7 no.4
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• pp.297-319
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• 2022

Due to their natural and social revelation, also their ease and flexibility, human collective behavior and teamwork sports are inspired to introduce optimization algorithms to solve various engineering and scientific problems. Nowadays, meta-heuristic algorithms are becoming some striking methods for solving complex real-world problems. In that respect in the present study, the authors propose a novel meta-innovative algorithm based on soccer teamwork sport, suitable for optimization problems. The method may be referred to as the Soccer League Optimization-based Championship Algorithm, inspired by the Soccer league. This method consists of two main steps, including: 1. Qualifying competitions and 2. Main competitions. To evaluate the robustness of the proposed method, six different benchmark mathematical functions, and two engineering design problem was performed for optimization to assess its efficiency in achieving optimal solutions to various problems. The results show that the proposed algorithm may well explore better performance than some well-known algorithms in various aspects such as consistency through runs and a fast and steep convergence in all problems towards the global optimal fitness value.

• The Journal of the Korea Contents Association
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• v.11 no.6
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• pp.59-66
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• 2011

Resource constrained project scheduling problem with multiple resource constraints as well as precedence constraints is well-known as one of the NP-hard problem. Since these problems can't be solved by the deterministic method during reasonable time, the heuristics are generally used for getting a sub-optimal during reasonable time. In this paper, we introduce an efficient genetic algorithm for resource constrained project scheduling problem using crossover which is applying schema theory and real world tournament selection strategy. Experimental results showed that the proposed algorithm is superior to conventional algorithm.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.5
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• pp.467-476
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• 2020

Indoor space has been one of the focal points for geospatial research as various factors such as increasing demands for application and demand for adaptive response in emergencies have arisen. IndoorGML (Indoor Geography Markup Language) has provided a standardized method of representing the topological aspect of micro-scale environments, with its extensive specifications and flexible applicability. However, as more real-world problems and needs demand attention, suggestions to improve this standard, such as representing IndoorPOI (Indoor Points of Interest), have arisen. Hence, existing algorithms and functionalities that we use on perceiving these indoor spaces must also adapt to accommodate said improvements. In this study, we explore how to define spatial neighborhoods in indoor spaces represented by an integrated IndoorGML and IndoorPOI data. We revisit existing approaches to combine the aforementioned datasets and refine previous approaches to perform neighborhood spatial queries in 3D. We implement the proposed algorithm in three use cases using sample datasets representing a real-world structure to demonstrate its effectiveness for performing indoor spatial analysis.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.546-553
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• 2012

Compact routing intends to achieve good tradeoff between the routing path length and the memory overhead, and is recently considered as a main alternative to overcome the fundamental scaling problems of the Internet routing system. Plenty of studies have been conducted on compact routing, and quite a few universal compact routing schemes have been designed for arbitrary network topologies. However, it is generally believed that specialized compact routing schemes for peculiar network topologies can have better performance than universal ones. Studies on complex networks have uncovered that most real-world networks exhibit power-law degree distributions, i.e., a few nodes have very high degrees while many other nodes have low degrees. High-degree nodes play the crucial role of hubs in communication and inter-networking. Based on this fact, we propose two highest-degree landmark based compact routing schemes, namely HDLR and $HDLR^+$. Theoretical analysis on random power-law graphs shows that the two schemes can achieve better space-stretch trade-offs than previous compact routing schemes. Simulations conducted on random power-law graphs and real-world AS-level Internet graph validate the effectiveness of our schemes.

• School Mathematics
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• v.2 no.1
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• pp.203-241
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• 2000

This study aims to suggest a model of task development for mathematics performance assessment and to develop performance tasks for the fifth graders in the primary school on the basis of this model. In order to achieve these aims, the following inquiry questions were set up: (1) to develop open-ended tasks and projects for the fifth graders, (2) to develop checklists for measuring the abilities of mathematical reasoning, problem solving, connection, communication of the fifth graders more deeply when performance assessment tasks are implemented and (3) to examine the appropriateness of performance tasks and checklists and to modify them when is needed through applying these tasks to pupils. The consequences of applying some tasks and analysing some work samples of pupils are as follows. Firstly, pupils need more diverse thinking ability. Secondly, pupils want in the ability of analysing the meaning of mathematical concepts in relation to real world. Thirdly, pupils can calculate precisely but they want in the ability of explaining their ideas and strategies. Fourthly, pupils can find patterns in sequences of numbers or figures but they have difficulty in generalizing these patterns, predicting and demonstrating. Fifthly, pupils are familiar with procedural knowledge more than conceptual knowledge. From these analyses, it is concluded that performance tasks and checklists developed in this study are improved assessment tools for measuring mathematical abilities of pupils, and that we should improve mathematics instruction for pupils to understand mathematical concepts deeply, solve problems, reason mathematically, connect mathematics to real world and other disciplines, and communicate about mathematics.

• Research in Mathematical Education
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• v.27 no.1
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• pp.25-47
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• 2024

Mathematical modeling activities are gaining popularity in K-12 mathematics education curricula worldwide. These activities serve dual purposes by aiding students in making sense of real-world situations intertwined with social justice while acquiring mathematical knowledge. Despite efforts to prepare teacher candidates for instructing in mathematical modeling within a single country, little attention has been given to teacher candidates' approaches to mathematical modeling on a social justice issue from different countries. This article employs an in-depth, small-scale comparative study to examine the approaches of U.S. and Korean teacher candidates in solving a justice-oriented mathematics task. Our findings reveal that, although both U.S. and Korean teacher candidates identified certain variables as key when constructing a mathematical model, Korean teacher candidates formulated a more nuanced model than U.S. candidates by considering diverse variables. However, U.S. teacher candidates exhibited a heightened engagement in linking the task to social justice issues, whereas Korean teacher candidates barely perceived real-world problems in relation to social justice concerns. This study serves as a valuable tool to inform the roles and limitations of teacher education programs, shaped within specific educational contexts.

• Journal of Cadastre & Land InformatiX
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• v.49 no.2
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• pp.123-134
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• 2019

The introduction of the world geodetic reference system in cadastral sector can apply the international standardization of cadastral survey and can be the basis for the creation of new industries by merging with other industries based on spatial information. With the introduction of the world geodetic reference system, non-coincidence land may cause problems which are whether the cadastral record and the real estate register are not consistent, etc. This problem infringes on the protection of ownership of citizens suggested in the main purpose of ｢Act On The Establishment, Management, Etc. Of Spatial Data｣. We have analyzed at overlapping cases between private land and overlapping cases between national and public land and suggested institutional improvement measures to solve problems arising on the site. As a result, it will be necessary to introduce a transformation verification measure by the world geodetic reference system in order to assign a function as a cadastral records to mapping converted to the world geodetic reference system. It is also expected that the legal and institutional basis should be established for alert adjustment and positioning through verification measures. Finally, it is difficult to determine the transformation factor as the co-ordinates of common points also differ because survey results vary by work area. Therefore, it is deemed necessary to consider the requirement to use the cadastral measurement basis by the world geodetic reference system in 2021.