• Convergence Security Journal
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• v.16 no.3_1
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• pp.47-56
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• 2016

This study's goal is to consider deeper about the Context-Communication Study on candidates of future petty officers in community colleagues, therefore the study uses theoretical approaches of the communications based on literature research. The petty officer majors in community colleagues need to set a curriculum to achieve the goal of the Context-Communication Study. The class, which is a continuous class from freshman to sophomore year, needs to be designed as a combination class of command/discipline major classes and communication studies. This study shows the detail ways of the Context-Communication Study to bring student's interests by using simulation studies with writing papers, training interviews, and presentations which all will be checked by their instructors. Instructors will get students to the point that they have upscale communication abilities and language abilities. Finally, this study shows limitations of the Context-Communication Study and suggests the further direction of research.

• Transactions of the KSME C: Technology and Education
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• v.4 no.2
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• pp.75-83
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• 2016

Since fire is one of the most dangerous threats to the safety of the ship, from the safety device is installed on the vessel the digestive apparatus can be viewed as the most important safety device. The fire-extinguishing device to be mounted to the vessel structure affected the stability of the structure in accordance with the blue of the sea. In particular, the Rack part of the basic safety of a fixed fire extinguishing system in the absence of a $CO_2$ container. In this paper, by utilizing simulation techniques to apply the pressure data being ejected in each direction by ship motion and $CO_2$ containers Rack perform an analysis of the structural safety assessment was part of the digestive system accordingly.

• Applied Microscopy
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• v.28 no.3
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• pp.415-424
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• 1998

The dependency of long-range order parameter on the ordered structure of $Pb(Mg_{1/3}Nb_{2/3})O_3$ solid solutions has been investigated by means of computer simulations of high-resolution lattice images. The computer image simulations were performed by the multislice method in a wide range of sample thicknesses, defocusing values, and long-range order parameters. It was found that the lattice images of the ordered structures were predominantly dependent on the long-range order parameter, The lattice images in a complete ordered structure showed a pseudo-hexagonal pattern. As the order parameter decreases, the simulated images changed slowly from a pseudo-hexagonal pattern to a rectangular pattern. The lattice images in a complete disordered structure showed a rectangular pattern. Also, the simulated images of the $Pb(Mg_xNb_{1-x})O_3$ with different Mg:Nb ratios obtained at a given long-range order parameter were basically the same patterns, irrespective of Mg and Nb compositions.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2052-2060
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• 2006

The wear of engine valve and seat insert is one of the most important factors which affect engine performance. Because of higher demands on performance and the increasing use of alternative fuel, engine valve and seat insert are challenged with greater wear problems than in the past. In order to solve the above problems, a simulator was developed to be able to generate and control high temperatures and various speeds during motion. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity. This work focuses on the different degrees of wear at three different singular test speeds (10 Hz, 25 Hz & multi-Hz). For this study, the temperature of the outer surface of the seat insert was controlled at 350$^{\circ}C$, and the test load was 1960 N. The test cycle number was $6.0{\times}10^6$. The mean ($\pm$standard error) wear depth of the valve at 10 Hz and 25 Hz was 45.1 ($\pm$3.7)$\mu$m and 81.7 ($\pm$2.5)$\mu$m, respectively. The mean wear depth of the seat insert at 10 Hz and 25 Hz was 52.7 ($\pm$3.9)$\mu$m and 91.2 ($\pm$2.7)$\mu$m, respectively. In the case of multi-Hz it was 70.7 ($\pm$2.4)$\mu$m and 77.4 ($\pm$3.8)$\mu$m, respectively. It was found that higher speed (25 Hz) cause a greater degree of wear than lower speed (10 Hz) under identical test condition (temperature, valve displacement, cycle number and test load). In the wear mechanisms of valves, adhesive wear, shear strain and abrasive wear could be observed. Also, in the wear mechanisms of seat inserts, adhesive wear, surface fatigue wear and abrasive wear could be observed.

• Journal of Digital Contents Society
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• v.11 no.2
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• pp.203-216
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• 2010

This study analyzed educational applications in smartphones with some criteria seeking to apply online learning characteristics to smartphones. For the analysis, 85 educational applications were selected and they were classified by types of educational contents, interactions, and the combination of the educational contents and interactions. As a result, drill-and-practice and tool types of contents ranked high, and there found to be few simulation and problem solving types. In regard to interaction types, almost all of the applications had interactions only between contents and learners, which meant little active communications when using applications. Therefore, enhanced interactions and communications among learners using the social network service platform were required in order to use educational applications in a more effective way.

• Journal of Environmental Science International
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• v.25 no.7
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• pp.1017-1028
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• 2016

Wind information is one of the major inputs for the prediction of urban air flow using computational fluid dynamic (CFD) models. Therefore, the numerical characteristics of the wind data formed at their mother domains should be clarified to predict the urban air flow more precisely. In this study, the formation characteristics of the wind data in the Seoul region were used as the inlet wind information for a CFD based simulation and were analyzed using numerical weather prediction models for weather research and forecasting (WRF). Because air flow over the central part of the Korean peninsula is often controlled not only by synoptic scale westerly winds but also by the westerly sea breeze induced from the Yellow Sea, the westerly wind often dominates the entire Seoul region. Although simulations of wind speed and air temperature gave results that were slightly high and low, respectively, their temporal variation patterns agreed well with the observations. In the analysis of the vertical cross section, the variation of wind speed along the western boundary of Seoul is simpler in a large domain with the highest horizontal resolution as compared to a small domain with the same resolution. A strong convergence of the sea breeze due to precise topography leads to the simplification of the wind pattern. The same tendency was shown in the average vertical profiles of the wind speed. The difference in the simulated wind pattern of two different domains is greater during the night than in the daytime because of atmospheric stability and topographically induced mesoscale forcing.

• Journal of Advanced Navigation Technology
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• v.14 no.4
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• pp.530-536
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• 2010

This paper proposes a QoS/QoE guaranteeing scheme by reassembling packets that have already been delivered to the end systems under the condition that there is no other way to fulfill user's QoS/QoE with the current network conditions. The proposed scheme is a QoS/QoE provisioning scheme that can be applied when IPTV streaming packets have not been consecutively received by the receiver. The receiving end system modifies the continuous counter field in the MPEG-2 Transport Stream and reassembles packets based on this information. In the simulation, broadcasting streaming environment has been implemented in order to verity the QoS/QoE performance of the proposed scheme under the good and poor network conditions.

• Journal of Advanced Navigation Technology
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• v.18 no.2
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• pp.170-177
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• 2014

Genetic Algorithms are robust search and optimization techniques but have some problems such as premature convergence and convergence to local extremum. As population diversity converges to low value, the search ability decreases and converges to local extremum but population diversity converges to high value, then the search ability increases and converges to global optimum or genetic algorithm may diverge. To guarantee that genetic algorithms converge to the global optima, the genetic operators should be chosen properly. In this paper, we propose the genetic operators with the hybrid function of the average Hamming distance and the fitness value to maintain the diversity of the GA's population for escaping from the premature convergence. Results of simulation studies verified the effects of the mutation operator for maintaining diversity and the other operators for improving convergence properties as well as the feasibility of using proposed genetic operators on convergence properties to avoid premature convergence and convergence to local extremum.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.76-85
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• 2018

The interest in the Building Information Modeling (BIM) technology has risen remarkably due to the effects on construction work period reduction, cost reduction, work safety improvement, and other factors. In civil engineering field, BIM applications mainly focus on data modeling and virtual construction. In this study, we present the BIM-based virtual construction and analyze the effects of BIM for the railway facilities so that the conventional approach to the equipment operation plan can be improved in order to prevent safety accidents which can result from unclear information during the operation plan. The BIM-based virtual construction technology is applied to establish the construction plan for the site with constraints, the installation of steel girder needs to be completed, avoiding interference with the existing high-speed railway operation within a given limited time. A virtual construction model consisting of topography, structures, equipments, and avatar was built and more detailed model, including safety guard rails, was then created. Specifications of the construction equipment were input as a database, and the virtual construction model was manipulated in the equipment operation planning. Through the BIM-based virtual construction, including the verification of alternative construction method, 311 million won was saved and the construction period was shortened by 87 days compared to the original plan. In addition, it was shown that the interest and participation of the construction workers can be increased by providing the 3D virtual scene for real construction work and various safety hazards occurring during equipment operation can be effectively removed in advance by the interactive worker education.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1379-1385
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• 2017

Virtual training is a kind of training that proceeds as if it were a real situation. In recent years, there has been a growing demand for experiencing a situation in which a virtual reality technology has not been experienced directly in the real world due to the rapid development of the technology. Especially, safety education is very necessary in Korea where safety accidents are caused by many disasters. Therefore, simulation of disaster response training using virtual reality is more urgent than ever. Although the automatic defibrillator is the medical device that is most needed to rescue patients with cardiac arrest, few people know how to use it. Therefore, there are very few cases where the use of automatic defibrillators has saved the patient's life in Korea. The proposed Automated External Defibrillator virtual training system enables immersive and experiential training in real situations and effective training at low cost.