• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.2
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• pp.153-161
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• 2009

A domain/boundary decomposition method is applied for efficient analyses of thermo-elasto-viscoplastic damage and contact problems under the assumption of infinitesimal deformation. For the decomposition of a whole domain and contact boundaries, all the equality constraints on the interface and contact interfaces are restated with simple penalty functional. Therefore, the non-linearity of the problem is localized within finite element matrices in a few subdomains and on contact interfaces. By setting up suitable solution algorithms, the computational efficiency can be improved considerably. The general tendency of the computational efficiency is illustrated with some numerical experiments.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.89-97
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• 1997

A genetic algorithm (GA) is a stochastic direct search strategy that mimics the process of genetic evolution. The GA applied herein works on a population of structural designs at any one time, and uses a structured information exchange based on the principles of natural selection and wurvival of the fittest to recombine the most desirable features of the designs over a sequence of generations until the process converges to a "maximum fitness" design. Principles of genetics are adapted into a search procedure for structural optimization. The methods consist of three genetics operations mainly named selection, cross- over and mutation. In this study, a method of finding the optimum topology of truss/beam structure is pro- posed by using the GA. In order to use GA in the optimum topology problem, chromosomes to FEM elements are assigned, and a penalty function is used to include constraints into fitness function. The results show that the GA has the potential to be an effective tool for the optimal design of structures accounting for sizing, geometrical and topological variables.variables.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.3
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• pp.1-8
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• 1998

This paper proposes a reinforcement genetic programming based on the reinforcement learning method for the performance improvement of genetic programming. Genetic programming which has tree structure program has much flexibility of problem expression because it has no limitation in the size of chromosome compared to the other evolutionary algorithms. But worse results on the point of convergence associated with mutation and crossover operations are often due to this characteristic. Therefore the sizes of population and maximum generation are typically larger than those of the other evolutionary algorithms. This paper proposes a new method that executes crossover and mutation operations based on reinforcement and inhibition mechanism of reinforcement learning. The validity of the proposed method is evaluated by appling it to the artificial ant problem.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.93-100
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• 1996

In this paper, a computer simulationtechnique for the forging process having a spring-attached die was presented . The penalty rigid-thermoviscoplastic finite element method was empolyed together with an interatively force-balancing method, in which the convergence was achieved when the forming load and the spring reaction force are in equilibrium within the user-specified allowable accuracy. The force balance was controled by adjusting the velocity of the spring-attched die. th minimize the number of internations, a velocity estimating schemewas proposed. Two application examples found in the related company were given. In the first application example, the predicted metal folw lines were compared with the acturally forged ones. in the second example, a hot forging process with a spring-attached die was simulated and the analyzed results were discussed in order to investigated the effects of spring-attached dies on the metal flow lines and the forming loads.

• The Korean Journal of Archival Studies
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• no.57
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• pp.35-73
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• 2018

This study aims to elucidate the implications for 20 years of the establishment of the information disclosure law by analyzing contents of the public regulations of 50 states of the United States. For the purpose, it looks at the general outline of the open meetings law of the 50 states, including the requirements and procedure of the advance notification of the meeting, and the protest procedure and penalties for the violation of the law. As a result of analysis, under the law, public meetings should announce their schedule and agenda in advance, and minutes of meetings and recording of meetings should be accessible to citizens. Furthermore, a person who violates the law for opening meetings could be fined or imprisoned. The implications for the establishment of the Open Meetings Act in Korea are as follows: First, the open meeting system starts with the appropriate period and method of advance notice of meeting holding. Second, the substantive contents of the advance notification guarantee the effectiveness of the meeting disclosure system. Third, the method and subject of advance notification should be as wide and diverse as possible. Fourth, all decisions of the meeting that violate the law are null and void. Fifth, a system should be set up so that any citizen could easily raise objections to the violation of the law. Sixth, the person who violates the law should be held responsible. Lastly, citizen access to minutes, recordings as well as comprehensive meeting minutes writing including attendees, agendas, and ballots should be guaranteed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.495-503
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• 2001

In a functionally graded materials(FGM), two constituent material particles are mixed up according to a specific volume fraction distribution so that its thermoelastic behavior is definitely characterized by such a material composition distribution. Therefore, the designer should determine the most suitable volume fraction distribution in order to design a FGM that optimally meets the desired performance against the given constraints. In this paper, we address a numerical optimization procedure, with employing interior penalty function method(IPFM) and FDM, for optimizing 2D volume fractions of heat-resisting FGMs composed of metal and ceramic. We discretize a FGM domain into finite number of homogenized rectangular cells of single design variable in order for the optimization efficiency. However, after the optimization process, we interpolate the discontinuous volume fraction with globally continuous bilinear function in order to enforce the continuity of volume fraction distributions.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.160-164
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• 2014

In this paper, an efficient robust design utilizing an enhanced Taguchi method is proposed to reduce cogging torque of a BLDC motor in the presence of design uncertainty. To overcome defects of the conventional Taguchi method in dealing with a generalized robust design problem, a penalty function and an optimal level searching technique are newly introduced. In order to verify the proposed method, a 5 kW, rated speed of 2,300 rpm, rated torque of 20 Nm BLDC motor for driving electric vehicles is optimized. Then, the robust design is compared with conceptual and deterministic ones in terms of the cogging torque, rated torque and torque ripple.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.829-837
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• 1992

This paper presents a new approach for the analysis of hot strip rolling processes. The approach is based on the finite element method and capable of predicting velocity field in the strip, temperature field in the strip, temperature field in the roll, and roll pressure. Basic finite element formulations for heat transfer analysis are described with emphasis on the treatment of numerical instability resulting from a standard Galerkin formulation. Comparison with the theoretical solutions found in the literature is made for the evaluation of the accuracy of the temperature solutions. An iterative scheme is developed for dealing with strong correlations between the metal flow characteristics and the thermal behavior of the roll-strip system. A series of process simulations are carried out to investigate the effect of various process parameters including interface friction, interface heat transfer coefficient, roll speed, reduction in thickness, and spray zone. The results are shown and discussed.

• The Korean Journal of Elementary Counseling
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• v.9 no.2
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• pp.175-193
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• 2010

The aim of this study is to examine effects of a yoga program for children on school stress of the elementary school children. To achieve this goal, total 10 students out of 231 in 6 classes among the third graders in M elementary school in B city were selected as subjects for this study. After regular school hours, they participated in a children's yoga program for 16 times for 45 minutes per session in the course of 8 weeks. An ethnographic interview was conducted to identify the effects of the program. During the initial stage of the children's yoga program, the participants were interviewed preliminarily. An analysis of areas and an analysis of classifications were made based on the initial interview results, and an area classification table was drawn on the school stress perceived by the elementary school children. After the yoga program ended, a follow up interview was made to apply an analysis of components by comparing changes in the school stress level due to a yoga effect. A research report was written through a cycle of addition and supplement in which the previous data analysis was complemented and corrected by new findings of the study. As a result of the ethnographic interview to analyze the school stress perceived by the elementary school children, and an examination of the changes in the school stress level, the children's yoga program proved to be significantly effective in reducing the school stress. However there were limitations to a certain degree in stress reduction. Details of such findings in each sub-category are as follow. First, as a result of the initial interview analysis, the school stress was classified broadly into 4 categories of study stress, friendship stress, teacher stress, and school environment stress. Second, the study stress as the first category of the school stress was classified into 3 sub-categories of homework, class, and exam stresses. In spite of minor differences among 3 sub-categories, the stress was reduced in general. Third, the friendship stress as the second category of the school stress was also classified into 3 sub-categories of bullying, alienation, and performing one's duty. There were minor differences among sub-categories, however stress reduction also appeared with the exception of the performing one's duty category which had relatively little effect from the yoga program. Fourth, regarding the teacher stress as the third school stress, a classification was made into 3 sub-categories of preference, penalty, and teaching method. Minor differences among the 3 sub-categories notwithstanding, stress reduction appeared with the exception of the teaching method stress which had relatively little effect from the yoga program. Fifth, the school environment stress as the fourth category of the school stress was classified into 2 sub-categories of school meals and facilities. Minor differences between the 2 categories notwithstanding, stress reduction appeared with the facilities stress having relatively little effect.

• Korean Security Journal
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• no.57
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• pp.177-203
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• 2018

Police Assigned to Special Guard Act was legislated in 1962 to solve issues regarding the protection of various staple industrial installations, and in 2001, the Security Services Industry Act was revised to establish an effective security system for important national facilities. Thereby the Special Guards System was instituted. The current law has two parts, with the Police Assigned to Special Guard System and Special Guards System, and many scholars have actively discussed the appropriateness of the integration of both systems to solve problems caused by a bimodal system. However, in spite of these discussions taking place in the academic world, the idea of unification lost its power when the guarantee of status regulation was established for the police assigned to special guard. Strictly speaking, police assigned to special guard is a self-guard, and a special guard is a contractual guard. So, both of them have pros and cons. Thus, it would be desirable to give a legal, constitutional guarantee for both systems by strengthening each of them and making up for the weakness of each of them rather than trying to unify police assigned to special guard and special guard. To begin this process, we need to revise unreasonable legal provisions of Security Services Industry Act and Police Assigned to Special Guard Act as below. First, since the actual responsibilities of special guards and police assigned to special guard duty are the same, we need to make the facilities which they use equal. Second, legal provisions need to be revised so that a special guard may perform the duties of a police officer, according to the Act on the Performance of Duties by Police Officers, within the facility that needs to be secured in order to prevent any vacancy in the guarding of an important national facility. Third, disqualifications for the special guards need to be revised to be the same as the disqualifications for the police assigned to special guard duty. Fourth, it is reasonable to unify the training institution for special guards and for police assigned to special guard duty, and it should be the training institution for police. On-the-job education for a security guard needs to be altered to more than 4 hours every month just like the one for police assigned to special guard duty. Fifth, for a special guard, it is not right to limit the conditions in their using weapons to 'use of weapon or explosives' only. If one possesses 'dangerous objects such as weapon, deadly weapon, and so on' and resists, a special guard should be able to use their weapon against that person. Thus, this legal provision should be revised. Sixth, penalty, range of fines, and so on for police assigned to special guard duty need to be revised to be the same as the ones for a special guard. If we revise these legal provisions, we can correct the unreasonable parts of Security Services Industry Act and Police Assigned to Special Guard Act without unifying them. Through these revisions, special guards and police assigned to special guard duty may develop the civilian guard industry wholesomely under the law, and the civilians would have a wider range of options to choose from to receive high quality security service.