• Journal of Korean Institute of Industrial Engineers
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• v.33 no.3
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• pp.290-302
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• 2007

This paper introduces several decision-making problems that need to be solved in order to facilitate the efficient operation of container terminals. These decision-making problems include the berth planning problem, the quay crane scheduling problem, the unload/load sequencing problem, the yard allocation problem, and the short-term scheduling of transporters and yard cranes. These problems can be classified into strategic decision problems, tactical decision problems, and real time operational decision problems. This paper proposes definitions of the problems that can be used to develop mathematical models for the problems.

• Smart Structures and Systems
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• v.20 no.2
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• pp.115-126
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• 2017

The modal identification of large civil structures such as bridges under the ambient vibrational conditions has been widely investigated during the past decade. Many operational modal analysis methods have been proposed and successfully used for identifying the dynamic characteristics of the constructed bridges in service. However, there is very limited research available on reliable criteria for the robustness of these identified modal parameters of the bridge structures. In this study, two time-domain operational modal analysis methods, the data-driven stochastic subspace identification (SSI-DATA) method and the covariance-driven stochastic subspace identification (SSI-COV) method, are employed to identify the modal parameters from field recorded ambient acceleration data. On the basis of the SSI-DATA method, the modal contribution indexes of all identified modes to the measured acceleration data are computed by using the Kalman filter, and their applicability to evaluate the robustness of identified modes is also investigated. Here, the benchmark problem, developed by Hong Kong Polytechnic University with field acceleration measurements under different excitation conditions of a cable-stayed bridge, is adopted to show the effectiveness of the proposed method. The results from the benchmark study show that the robustness of identified modes can be judged by using their modal contributions to the measured vibration data. A critical value of modal contribution index of 2% for a reliable identifiability of modal parameters is roughly suggested for the benchmark problem.

• Journal of the Korea Safety Management & Science
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• v.16 no.1
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• pp.69-77
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• 2014

The environment and requirements of modern war fields have been affected and thus changed by a variety of issues. To this end, the development of safety-critical weapon systems frequently need to meet those changes even in the operational phase. The necessity of the changes may be due to the preparation for mass-production or the request originated from the user military forces. To meet such a need can be even tougher in the development of safety-critical weapon systems since the integration of the requirements for both systems design and systems safety would make it troublesome. To handel the matter in this paper, utilization of architecture DB is proposed. Specifically, the situation in demand has first been analyzed and then a problem-solving process to accommodate the design changes has been constructed. In doing so, the concept of the aforementioned integration is particularly focused on the functional architecture, which could be a core concept of our approach to solving the problem. The result of a case study demonstrating the method studied using a computer-aided systems engineering tool is also presented.

• East Asian mathematical journal
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• v.24 no.5
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• pp.547-564
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• 2008

The purpose of this study was to investigate 5th graders' performance for mixed operational problem. For this purpose. two kinds of studies were conducted: a descriptive study by pencil and paper tests(32 problems) and a clinical study by interviews. The conclusions drawn from the results obtained in this study were as follows: First, students were highly scored in pencil and paper tests(M=85.25%). But that score is not up to scratch. Because the problem was composed of simple calculations and if students calculate problems from only let side, they gel 75% right answer, etc. Second, most of students solved mixed operational problems by text-based way, but some students solved flexibly. There are several error types. The main error type is students' following the wrong order of calculations. Some students have obstacles to express their thought with numerical expressions. So they make errors. Third, students solve mixed operational problems with various strategies. For examples, they solve problems by describing calculation procedures, drawing lines to indicate the order of calculations, carrying out two numerical expressions, etc.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.793-796
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• 1996

This study proposes a new algorithm which performs a production simulation under various constraints and maintains computational efficiency. In order to consider the environmental and operational constraints, the proposed algorithm is based on optimization techniques formulated in LP form In the algorithm, "system characteristic constraints" reflect the system characteristics such as LDC shape, unit loading order and forced outage rate. By using the concept of Energy Invariance Property and two operational rules i.e. Compliance Rule for Emission Constraint, Compliance Rule for Limited Energy of Individual Unit, the number of system characteristic constraints is appreciably reduced. As a solution method of the optimization problem, the author uses Karmarkar's method which performs effectively in solving large scale LP problem. The efficiency of production simulation is meaningful when it is effectively used in power system planning. With the proposed production simulation algorithm, an optimal expansion planning model which can cope with operational constraints, environmental restriction, and various uncertainties is developed. This expansion planning model is applied to the long range planning schemes by WASP, and determines an optimal expansion scheme which considers the effect of supply interruption, load forecasting errors, multistates of unit operation, plural limited energy plants etc.

• Journal of The Korean Association For Science Education
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• v.9 no.1
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• pp.19-37
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• 1989

The purpose of this study was to investigate the development of logical thinking and scientific reasoning pattern of Korean high school students. To carry out this study subjects were selected about 2,000 Junior high school students, and about 4,100 senior high school students throughout the nation. They were identified as concrete, transitional or formal operational stage with the use of TOLT(the Test of Logical Thinking) by Tobin and Capie(1980), and TOSR(the Test of Scientific Reasoning) by W.A Farmer(1986). This study turned out that more than 76% of Junior high school students were classified as the concrete operational stage and about 44% of senior high school students were classified as the formal operational stage, while about 26% of them were still in the concrete operational level. This study showed that the main factor of the intellectual development of students is learning by the gradual advancement of their grades and especially entrance into the senior high school rather than by the physical growth. This study also showed that there are the take-off stage of the development of logical thinking between fourteen and fifteen years of their ages. Less than 25% of junior high school students were in the formal operational stages which are capable of control of variables, probabilistic, correlation and combinational logic in problem-solving situation, while 33-54% of senior high school students were in the formal operational levels. 38% of junior high school students were in the formal operational stage which is capable of proportional logic, while about 55% of senior high school students were in the formal operational stage. Less than 20% of senior high school students were classified as group of highly capable of scientific reasoning, while more than 23% of them were classified as group of poor capability. It also turned out that there are differences or no differences between male and female students of each school in problem-solving situation regarding each logic approach. These differences were proved to be fluctuating depending on the situations and their grades. The other results of this study is similar to those of other researches such as Tomlinson-Keasey 1972, Coleman 1973, Lawson 1973, Lawson and Renner 1974, Neimark 1975, Han 1982, and Kim 1989.

• Journal of Distribution Science
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• v.12 no.9
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• pp.113-123
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• 2014

Purpose - After Korea's Free Economic Zone (FEZ) system was launched in 2003, there have been many debates about upgrading it and its support systems. However, as of 2013, there were insufficient results. Further, upon the designation of the East Coast and Chungbuk as official FEZs from February 4, 2013 by the 56th the Commission, there is a concern that many people are in the area designated as FEZ 8. This study investigates Korea's new FEZ system as part of Korea's primary new economic development policy in the 21st century. Therefore, this study examines views on the weaknesses of the past ten years of FEZs so that Korea can expand its FEZ system. Research design, data, and methodology -Many countries have considered the FEZ as an economic special zone. By reviewing previous research models, this study provides an update using recent data and materials, until 2013, from the Center of Free Economic Zones. In previous studies, the lack of support systems was attributed to proposals to ensure operational autonomy and differentiation of each FEZ; however, the main cause cannot be solved through regulatory issues, as difficulties caused by the operational system are responsible for the problems. We wish to analyze the FEZ, specifically the operational system; this is the main issue of this study. Results - After the first FEZs were established, it became necessary to have basic plans, as investment results in 2013 compared to the same period this year led to lower earnings in the first half of 2014. We propose an improvement of the operational system because in the free economic zones, the operational system is the root cause of the underlying problem. The results of this research are as follows. The weak management of the FEZ system is influenced by weak investment, delayed development, foreigners' living facilities, benefits of foreign investments, the control tower's policy making decision process, quickness of the process of satisfying legal requirements, and support For the independence of FEZs. Conclusion - Local governments do not have legal rights over FEZ deregulation and investment industries. This study suggests that the local government should have more independence from the central government. Moreover, independent management committees are more effective for ensuring public rights, better employee responsibilities, and better-qualified personnel. The FEZ committee struggles to effectively manage the locations of FEZs, foreign investments, and related facilities under the control of the Ministry of Trade, Industry and Energy. Thus, the FEZ committee should be under either the Prime Minister's office or the Presidential committee, to control and effectively coordinate between the local and central governments. If the problem clearly applies to the operational system in 2013, it is necessary to provide materials and methods so that the results of the first half of 2014 can be computed despite the data limits and lack of resources, and the data can be analyzed in a more diachronic thesis.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.65-77
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• 2013

In this paper, we develop the operational Tau method for solving nonlinear Volterra integro-differential equations of the second kind. The existence and uniqueness of the problem is provided. Here, we show that the nonlinear system resulted from the operational Tau method has a semi triangular form, so it can be solved easily by the forward substitution method. Finally, the accuracy of the method is verified by presenting some numerical computations.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.500-505
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• 1995

This paper describes the results of simulation of a CANDU operational transient problem (re-startup after short shutdown) using the Coupled Reactor Kinetics(CRKIN) code developed previously with CANDU Reactor Regulating System(RRS) logic. The performance in the simulation is focused on investigating the behaviours of neutron power and regulating devices in accordance with the changes of xenon concentration following the operation of the RRS.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.829-831
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• 1999

This paper considers the problem of identifying the time-varying parameters of Bilinear systems. The Parameters, in this paper, are identified by using the EBPOMs (Extended Block Pulse Operational Matrices) which can reduce the burden of operation and the volume of error caused by matrices multiplication