• Management Science and Financial Engineering
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• v.6 no.2
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• pp.29-45
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• 2000

We consider the design of a two-level telecommunication network having logical full-mesh/star topology, with the implementation of conduit systems taken together. The design problem is then viewed as consisting of three subproblems: locating hub facilities, placing a conduit network, and installing cables therein to configure the logical full-mesh/star network. Without partitioning into subproblems as done in the conventional approach, the whole problem is directly dealt with in a single integrated framework, inspired by some recent successes with the approach. We successfully formulate the problem as a variant of the classical multicommodity flow model for the fixed charge network design problem, aided by network augmentation, judicious commodity definition, and some flow restrictions. With our optimal model, we solve some randomly generated sample problems by using CPLEX MIP program. From the computational experiments, it seems that our model can be applied to the practical problem effectively.

• Journal of Engineering Education Research
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• v.20 no.5
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• pp.34-42
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• 2017

This study aimed to identify the causal relationships among self-regulated learning strategy, problem solving efficacy, task value and learning outcome, and mediation effect of self-regulated learning strategy in engineering capstone design course. The data were collected from 363 university students who enrolled in capstone design courses and analyzed using structural equation modeling method. The results were: first, problem-solving efficacy and task value exerted significant effects on self-regulated learning strategy. Second, self-regulated learning strategy exerted significant effects on learning outcome, but problem-solving efficacy and task value did not. Third, problem-solving efficacy and task value showed significant indirect effects on learning outcome, which confirmed that self-regulated learning strategy fully mediated between two exogenous variables and learning outcome.

• Computers and Concrete
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• v.26 no.1
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• pp.1-10
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• 2020

In this paper, a procedure for automated optimized design of reinforced concrete frames has been presented. The procedure consists of formulation and solution of the design problem in the form of an optimization problem. The minimization of total cost of R/C frame has been taken as the objective of optimization problem. In this research, consistent approximation method is applied to explicitly formulate constraints and objective function in terms of the design variables. In the presented method, the primary optimization problem is replaced with a sequence of explicit sub-problems. Each sub-problem is efficiently solved using the Sequential Quadratic Programming (SQP) method. The proposed method is demonstrated through a four-story frame and an eight-story frame, and the optimum results are compared with those in the available literature. It is shown that the proposed method can be easily applied to obtain rational, reliable, economical and practical designs for Reinforced Concrete Moment Resisting Frames (RCMRFs) while it is converged after a few analyses.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.67-84
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• 2000

In this paper, we address a network design problem including the decision of hub facility locatiions which is typically found in a communicatio and a transportation network design studies. Due to the administrative and the geographical restrictions, it is common to assume that each user should be assigned to only one hub facility. To construct such a network, three types of network costs should be considered: the fixed costs of establishing the hubs and the arcs in the network, and the variable costs associated with transversing the network. The complex problem is formulated as a mixed IP embedding a multicommodity flow problem. Exploiting its special structure, a dual-based heuristic is then developed, which yields near-optimal design plans. The test results indicate that the heuristic is an effective way to solve this computationally complex problem.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.581-587
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• 2008

This paper presents a railway network design problem (RNDP), which can be formulated as a bi-level program. In bi-level program upper level program is to minimize total travel cost including the construction cost of the railway facilities, whilst lower one describes the railway route choice behavior of passengers. We also propose a heuristic method for solving the program because it is a kind of NP-hard problem. From two numerical railway examples, we confirm that the RNDP and its algorithm produce a reasonable solution and that it is applicable to real world.

• Journal of The Korean Association of Information Education
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• v.22 no.4
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• pp.427-438
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• 2018

The purpose of this study is to analyze the effect of SW education applying CSCL based design thinking on elementary school students' creativity and problem solving skills. The study was conducted on 28 elementary school students in grades 4,5,6 participated in J university-sponsored educational donation program during the winter break. A SW education program based on design thinking was developed and applied to experimental group. First, we conducted a pre-test to check creativity and problem solving skills. After that, SW education program applying CSCL-based design thinking was conducted for 42 hours. Finally, post-test was conducted to examine creativity and problem solving skills. As a creativity test tool, the TTCT pattern test forms A and B of Torrance were used and analyzed. As the problem solving skills test tool, the problem solving skills test for the elementary school students developed as a life-ability measurement tool were used and analyzed. As a result of the verification, it was found that SW education applying design thinking was effective in improving elementary school students' creativity and problem solving skills.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.223-233
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• 2021

This study is was conducted for 37 first-year students (including 27 males and 10 females) enrolled in the engineering product design class opened as a regular class in the second semester of 2018 at 'A' University in Seoul to examine creative problem solving experiences in class using design_thinking. In this study, creative problem-solving ability was divided into creative personality and problem-solving ability and in the results of examining the difference in pre- and post-creative problem solving abilities through Hotelling's T-square test and t-test, among the creative personality, the tolerance & passion, humor, curiosity, and progressive attitude were found to significantly increase after class. Next, in the results of examining the process of creative problem solving through the reflection journal, in the empathy and prototyping and testing stages of design thinking, more activities for problem solving appeared, and at the stage of problem definition and idea generation, it can be seen that more activities expressing creative personality appear. The results of this study show that creative problem-solving abilities can be improved through design thinking, suggesting that instructional support for effective design thinking should be designed.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.1-9
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• 2011

An optimal design method for a structural control system considering load variations due to their uncertain characteristics is studied in this paper. The conventional design problem for a control system generally deals with the optimization problem of a structural control system and interaction between the structure and the control device. This study deals with the optimization problem of a load-structure-control system and the more complicated interactions with each other. The problem of finding the load that maximizes the structural responses and the structural control system that minimizes the responses simultaneously is formulated as the min-max problem. In order to effectively obtain the optimal design variables, a co-evolutionary algorithm is adopted and, as a result, an optimal design procedure for the linear structural control system with uncertain dynamic characteristics is proposed. The example design and simulated results of an earthquake excited structure validates the proposed method.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.708-713
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• 2000

The design of experiment(DOE) is getting more attention in the engineering community since it is easy to understand and apply. Recently, engineering designers are adopting DOE with orthogonal arrays when they want to design products in a discrete design space. In this research, a design flow with orthogonal arrays is defined fur structural design according to the general DOE. The design problem is defined as a general structural optimization problem. Sensitivity information is evaluated by the analysis of variance(ANOVA), and an optimum design is determined from analysis of means(ANOM). Interactions between design variables are investigated to achieve additivity which should be valid in DOE. When strong interactions exit, a method is proposed. Some methods to consider the problem are suggested.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.227-234
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• 2023

In this paper, we developed a design thinking-based artificial intelligence education program for middle school students and applied it to verify the impact on creative problem-solving skills. The inspection tool used the Creative Problem Solving Profile Inventory (CPSPI), an inspection tool for measuring creative thinking type ability based on the CPS theory of Hwasun Lee, Jungmin Pyo, Insoo Choe(2014). CPSPI included the steps of evaluating cognitive preferences and cognitive abilities by supplementing the limitations of existing tests, and sharing and persuading one's ideas with others. Before and after applying the design thinking-based artificial intelligence education program, as a result of analyzing the creative problem-solving ability, it increased significantly in all areas. As a result of analyzing the creative problem-solving ability of middle school students, significant results were found in the areas of Problem Detection and Analysis, Idea Generation, Action plan, Execution, Persuasion and Communication. The effect of design thinking was confirmed as a teaching and learning method to improve creative problem-solving ability in artificial intelligence education.