• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.133-138
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• 1991

The aim of the present paper is to develop a computer program predicting ultimate fracture strength of initially cracked structure under monotonically increasing external loads. For this purpose, two kinds of 3-D isoparametric solid elements, one 6-node wedge element and another 8-node brick element are formulated along the small deformation theory. Plasticity in the element is checked using von Mises' yield criterion. Elasto-plastic stiffness matrix of the element is calculated taking account of strain hardening effect. If the principal strain at crack tip which is one nodal point exceeds the critical strain dependin on the material property, crack tip is supposed to be opened and the crack tip node which was previously constrained in the direction perpendicular to the crack line is released. After that, the crack lay be propagated to the adjacent node. Once a crack tip node is fractured, the energy of the newly fractured node should be released which is to be absorbed by the remaining part. The accumulated reaction force which was carried by the newly fractured node so far is then applied in the opposite direction. During the action of crack tip relief force, since unloading may be occured in the plastic element, unloading check should be made. If a plastic element unloads, elastic stress-strain equation is used in the calculation of the stiffness matrix of the element, while for a loading element, elasto-plastic stress-strain equation is continuously used. Verification of the computer program is made comparing with the experimental results for center cracked panel subjected to uniform tensile load. Also some factors affecting ultimate fracture strength of initially cracked plate are investigated. It is concluded that the computer program developed here gives an accurate solution and becomes useful tool for predicting ultimate fracture load of initially cracked structural system under monotonically increasing external loads.

• Journal of the Korea Concrete Institute
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• v.16 no.6 s.84
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• pp.785-794
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• 2004

This paper describes a new refined truss modeling technique derived based on the well-known relationship of V=dM/dx=zdT/dx+Tdz/dx in a reinforced concrete beam subjected to combined shear and moment loads. The core of the model is that a new perspective on the shear behavior can be gained by considering the variation of the internal arm length along the span, so that the shear resistance mechanism can be expressed by the sum of two base components; arch action and beam action. The sharing ratio of these two actions is determined by accounting for the compatibility of deformation associated to the two actions. Modified Compression Field Theory and the tension-stiffening effect formula in CEB/FIP MC-90 are employed in calculating the deformations. Then the base equation of V=dM/dx has been numerically duplicated to form a new refined truss model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.284-290
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• 2016

As the recently advanced scientific developments result in high lever of the usability and the needs for the electrical equipment and devices in various situations, the safety technologies protecting malfunction and electrical critical damages including soft and hardware from the unexpectedly radiated electromagnetic interferences are required gradually. In addition, the numerical analysis for the miniaturized electrical components and equipments as well as the conventional electrical devices installed inside the electrically large enclosures and structures requires the memory requirement and time consumption too big to be handled in a realistic situation, which will result in a limitation in solving the complete set of maxwell's equations. In this paper, PWB method based on statistical theory and topological modeling with appropriate zoning concepts are introduced for the EM analysis of an electrically large complex structures.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.597-600
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• 2008

Recently, Several Mega project are been performing as a multi-dimensional development project in Korea, but some problem has been revealed about deficiency of the history, experience, and skill. A multi-dimensional development project require the technology which can manage mega project to its specific at the level of program management. predicting schedule and schedule management are the most important for mega project, been performing over several years. This research shows the method of predicting and planning schedule in the early stage as a pre-study on developing a technology of schedule management. First of all, it presents the development of database considering the specific of mega project that can accumulate the history of schedule and search the schedule according to the type of single and multi building. Also it suggests the method of prediction schedule by creating scenarios according to owner requirements and cash flow, affecting schedule management in the early stage, and the shortening possibility of schedule duration using CCPM theory.

• Transactions of the KSME C: Technology and Education
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• v.2 no.2
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• pp.99-104
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• 2014

Convergence education is one of the most frequently studied topics in the academic world as well as other various areas of the society today. The importance of convergence-based course in engineering education has long been discussed and resulted in society-wide consensus with series of attempts to apply the theory. To bring about fruitful outcome through theses efforts, we have to establish the sustainable and systematic convergence education in engineering. With this goal, we will cover the critical comprehension on the modern studies divided by three concepts(the truth, the good, and the beauty) and review the notion of "Transdisciplinarity", thereby proposing the macro goals of the convergence-based course in engineering. To realize our goals, we will suggest "Engineering aesthetics" as a convergence-based course in engineering.

• Korean Security Journal
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• no.50
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• pp.287-303
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• 2017

Industrial security research has shown a rapid increase over the past decade. With the establishment of the Korean Association for Industrial Security in 2008 and the establishment of the departments of industrial security in recent years, academic interests and research on industrial security are also spreading at a rapid pace. Although academic interest and research have grown in quantitative terms, research on theoretical fields that are the basis of academic systematization is extremely limited. There is a focus on the issue of specific issues and practical solutions without worrying about the theoretical basis including conceptualization. Therefore, in most studies, the concept of industrial security remains at the level of accepting the concept applied in the previous research. Most industrial security research focuses on the specific topic of 'industrial technology protection' because it considers the concept of industrial security to be reduced to industrial technology protection. Although industrial security is composed of a wide range of fields, recognizing a specific field as an entirety of industrial security appears to be a serious problem. As a result, the concept of industrial security in industrial security research is being used ambiguously, incorrectly, and conveniently. It is necessary to accurately and recognize the concept of industrial security based on logical clarity and empirical feasibility.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.75-84
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• 2010

Controlled traffic intersection is critical point in terms of transportation network performance, where the most of traffic congestion arises. One of the most important and favorable measure of effectiveness in the signal controlled intersection is approach delay. Although lots of efforts to develop traffic delay estimation models have been made throughout the years, most of them were focusing on homogeneous traffic flow. The purpose of this research is to develop a traffic delay estimation model for traffic flow mixed with bus based on the horizontal shockwave theory. Traffic simulation is performed to test the adaptation level of the model in generic environment. The result shows that the delay increases with increasing bus traffic. Overall model accuracy comparing simulation result is acceptable, that shows the error range around 10 percent.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.109-120
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• 2010

This study aims to develop mathematical models for estimating saturation flow rates at the stop line of signalized intersection due to Workzones in the vicinity, since the saturation flow rate is the most critical parameter in capacity analysis for signalized intersections. It was found by reference review that saturation flow rates are sensitively influenced by the location of Workzone, the number of lanes, cycle length and effective green time. Extensive microscopic simulation runs were also performed and compared to the those of mathematical models for model verification. Mathematical models were developed based on traffic flow theory and dualizing them by the location of workzones. And then each result produced by changing important parameter values was carefully examined and analyzed. Small but consistent differences in saturation flow rate values between mathematical models and simulations exist. However, the pattern of changes in saturation flow rates depending on each variable was similar.

• Journal of Chest Surgery
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• v.24 no.11
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• pp.1081-1089
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• 1991

Atrial fibrillation is characterized by beat to beat irregularity of shape, size, conduction time and polarity. The mechanism of atrial fibrillation can be explained by so called "Multiple wavelet theory". The adverse effect of atrial fibrillation is the decrease of cardiac output by absence of atrial kick[10 ~ 15%] and the possibility of thrombosis in the left atrium which is dangerous to develop the thromboembolism is increased. The present study was designed to assess the effect of overdrive pacing on the suppression of recurring of atrial fibrillation after open heart surgery and the results were summarized as follows: 1. There were no significant differences of factors between converting patients and non-converting patients to normal sinus rhythm by electric cardioversion after open heart surgery. 2. Among converting patients to normal sinus rhythm, there were no significant differences of factors between study group and control group. 3. Cardiothoracic Ratio on the preoperative chest film was significantly larger in the patients of recurring atrial fibrillation within 72hrs than in the patients of maintaining normal sinus rhythm. [61.7$\pm$ 1.4% vs 67.7$\pm$2.4%, p=0.03] 4. There was a significant difference of suppressive effects between overdrive pacing group and control group among recurred cases until 24, 48, and 72hours [Fisher`s exact test ; p=0.037, p=0.076, p=0.53, respectively] 5. There was a difference of the delay of recurring of atrial fibrillation between study group and control group among recurred cases within 72 hours.[53.4$\pm$6.9hr vs. 19.3$\pm$3.8 hr, p<0.01] We think that the overdrive pacing may suppress the natural pacemaker and the converted normal sinus rhythm is maintained longer than control group during critical immediate postoperative period.ve period.

• Korean Journal of Logic
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• v.13 no.2
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• pp.27-59
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• 2010

After the unexpected death of the late professor Young-Jung Kim on July 28th last year, 4 pieces of paper unpublished were discovered. Those papers reveal that he had a grand program. In particular, we found that he had his own ideas and theory which he called "Presupposition Logic" and "Field Logic". In this paper, I will call his program "Presupposition Logic Program". He explored a new logic system, Presupposition Logic, in order to realize necessity and possibility of the closer relationship between logic and critical thinking. In this paper, I will expound what his "presupposition" and "Presupposition Logic" are and why he thought Presupposition Logic is necessary from a perspective of logic. And I will critically elucidate what was the problem that troubled him.