• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.699-709
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• 2014

This paper proposes a new method for predicting the derailment of a running train under cross-wind conditions, using the single wheelset derailment theory. The conventional theories used for predicting the derailment due to cross-winds were developed under the assumption that derailment will always be of the roll-over type, thus neglecting other possible types such as wheel-climbing, which may occur under special driving conditions. In addition, these theories do not consider running conditions such as dynamic wheel-rail interactions and friction effects. The new method considers the effects of dynamic wheel-rail interaction as well as those of lateral acceleration, rail cant, and cross-winds. The results of this method were compared and verified with those of the conventional methods and numerical simulations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.61-65
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by tile design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• The KIPS Transactions:PartB
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• v.9B no.2
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• pp.147-154
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• 2002

In bulding Intelligent Agent Societies (IAS), it is very important to design and implement coordination in accordance with the known requirement and anticipated working conditions. Coordination consists of a set of mechanisms necessary for the effective operation of IAS. Currently, there is little theoretical support that could help in this research is to generate an empirically-based solving systems in which all agent share an identical goal structure and fully cooperate. And we developed a simulation model called "P-System" which produces basic data to be used for statistical analysis to generate a theory of coordination. Coordination among agent in the P-System is dependent on 23 control variables calld TEs(tweakable emtities.)And the level of coordination is represennted by an independent variabe called QMC (Quality Measure Coordination) expressed in numerical terms according tn the definiion of this study. Also, we have studied how to select unbiased subset from the huge total experimental space of the P-System and how to decide the scale of the subset.

• Journal of Radiation Protection and Research
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• v.19 no.2
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• pp.109-120
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• 1994

A method for estimating the effectiveness of each protective action against a nuclear accident has been proposed using the fuzzy set theory. In most of the existing countermeasure models in actions under radiological emergencies, the large variety of possible features is simplified by a number of rough assumptions. During this simplification procedure, a lot of information is lost which results in much uncertainty concerning the output of the countermeasure model. Furthermore, different assumptions should be used for different sites to consider the site specific conditions. Tn this study, the diversity of each variable related to protective action has been modelled by the linguistic variable. The effectiveness of sheltering and evacuation has been estimated using the proposed method. The potential advantage of the proposed method is in reducing the loss of information by incorporating the opinions of experts and by introducing the linguistic variables which represent the site specific conditions.

• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.1
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• pp.165-172
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• 2012

For practical education, many practices using various practical equipments have to be provided to students. In this study, the application of learning curve to represent student's learning process in a practical education using a equipment was studied. Learning curve model was originally developed in production management and based on human performance in human factors aspects. In this study, the application of learning curve model was studied on the eye tracking system, which is used to evaluate the usability of a product in design area. As a case study for its applicability, practical education for eye tracking system was provided to three students and then task completion times were measured for hardware system setup and gaze image recording. Learning curves were estimated for two tasks and then task completion times were predicted using the learning curves. Through ANOVA(analysis of variance) and correlation analysis, the applicability of learning curve to practical education was analysed. As the result, learning curve could be effectively applied to practical eduacation using equipment.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.439-446
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• 2016

This research examines the effect of outside director system which has been legislated after financial crisis in Korea. Outside director system is based on agency theory which assumes that a manager is selfish and opportunistic in situation where ownership and management of a firm is separated. In this situation, outside director system has an important function to monitor and keep in check a manager. Thus, we examined that outside director system works as a monitoring mechanism in Korea. And we tested that above effect is weakened in family CEO firms where it is different from assumption of agency theory in Korea. According to empirical result with 282 sample firm, it is confirmed that outside director system reduces agency cost. In family CEO firms, however, this agency cost-reducing effect becomes weak. This result suggests that outside director system needs be cautiously managed without focusing on only monitoring function.

• Journal of Korean Society of Steel Construction
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• v.21 no.6
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• pp.563-574
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• 2009

This paper briefly describes the fundamental strategies--path-tracing, pin-pointing, and path-switching--in the computational elastic bifurcation theory of geometrically non-linear single-load-parameter conservative elastic spatial structures. The stability points in the non-linear elasticity may be classified into limit points and bifurcation points. For the limit points, the path tracing scheme that successively computes the regular equilibrium points on the equilibrium path, and the pinpointing scheme that precisely locates the singular equilibrium points were sufficient for the computational stability analysis. For the bifurcation points, however, a specific procedure for path-switching was also necessary to detect the branching paths to be traced in the post-buckling region. After the introduction, a general theory of elastic stability based on the energy concept was given. Then path tracing, an indirect method of detecting multiple bifurcation points, and path switching strategies were described. Next, some numerical examples of bifurcation analysis were carried out for a trussed stardome, and a pin-supported plane circular arch was described. Finally, concluding remarks were given.

• Journal of Korean Society of Archives and Records Management
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• v.18 no.2
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• pp.215-242
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• 2018

The record continuum theory is now being studied in Australia, wherein the segregated record management of current, semi-current, and past records based on the temporal flow of the life cycle theory are being critcized. In addition, it emerged as a new paradigm for electronic record management without time and spatial constraints. Moreover, it is recognized as a logical and conceptual entity rather than as a fixed physical object. It also makes it possible to record multiple records in consideration of the complex, multidimensional environment of records. Based on this record continuation theory, the current information and communications technology (ICT) is applied to the four axes and dimension of the record continuation diagram of theoretical researcher Frank Upward. The researchers aim to realize a video recording management method suitable for the electronic record age.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.23-30
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory. A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by the design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.366-375
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• 1992

The aminolysis of carbamates are studied MO theoretically using AM1 method. The results indicated that the reactivity is determined by bond-making and-breaking and steric effects; as a result the $B_{AC}2$ mechanism is favored due to favorable contribution of bond formation in agreement with experimental results. We found that although thermal 2＋2 reaction is forbidden, it becomes allowed when the total electrons involved are six in a four-center reaction and proceeds by a consecutive onestep mechanism. Comparison of activation barriers show that greater energy is required in breaking a sigma bond compared with the energy required for breaking a $\pi$ bond, by 17 kcal/mol and the six membered ring structure is favored about 5 kcal/mol sterically.