• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.55-65
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• 2002

In this study, the procedures for the preliminary design of the turbo-shaft engine for the light multi-purpose helicopter are established. The engine specifications are determined through the performance analysis on the on-design and off-design conditions by the use of simulation program. In addition, the effect of humidity on the engine performance is examined by considering the change of the gas properties and characteristic maps due to moisture contents. The calculation results show that the engine power is reduced by the existence of moisture in working fluid.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.4 no.2
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• pp.1-6
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• 2008

Very High Temperature Gas Cooled Reactor (VHTR) has been selected as a high energy heat source for nuclear hydrogen generation. The VHTR can produce hydrogen from heat and water by using a thermo-chemical process or from heat, water, and natural gas by steam reformer technology. A co-axial double-tube primary hot gas duct (HGD) is a key component connecting the reactor pressure vessel and the intermediate heat exchanger (IHX) for the VHTR. In this study, a preliminary design analysis for the primary HGD of the nuclear hydrogen system was carried out. These preliminary design activities include a determination of the size, a strength evaluation and an appropriate material selection. The determination of the size was undertaken based on various engineering concepts, such as a constant flow velocity model, a constant flow rate model, a constant hydraulic head model, and finally a heat balanced model.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.29-36
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• 2012

Involved in a research for the application of seismic isolation to the nuclear industry, this study evaluates firstly the responses of seismic isolation system considering general ranges of structural period and damping ratio by using preliminary design formula. Secondly, coupling effects of input motions were evaluated to find out appropriate conditions of excitations and effect of the iteration for calculating yield displacement of lead core was also assessed in terms of response of a seismically isolated structure. Finally, the results of preliminary design calculation were compared with those of dynamic analysis and the propriety of the formula was evaluated and appropriate ranges of reduction factor were also suggested from the results.

• Culinary science and hospitality research
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• v.12 no.4 s.31
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• pp.284-298
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• 2006

This study aimed at defining radish cultivars to a best cooking usage based on their physiochemical and textural characteristics of Nabakkimchi. Baekkwang, Daeburyong, Chungwoon and Taebaek were used as four types of radish cultivars. Nabakkimchi was stored at $8^{\circ}C$ either after fermentation for 12 hours at $25^{\circ}C$(A group) or without preliminary fermentation(B group). As storage period went by, lightness was decreased. Haziness of liquid showed sudden increase at preliminary fermentation in group A, while it increased between the third day and fifth day in group B. Hardness of 'Fall season' type was relatively high after storage. pH was suddenly decreased on the second day in A group and on the fifth day in B group. Acidity was suddenly increased on the second day in A group and since the third day at B group. As a result of sensory evaluation, Chungwoon stored for 2 days after preliminary fermentation was the best variety.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1178-1183
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• 2006

This paper describes the plans of considering the environmental influences in the preliminary feasibility investigation of railroad work. Because the cost-benefit analysis method about the environmental costs by air pollution and traffic noise is mainly applied in preliminary feasibility investigation, not only the verification in the calculation method of these environmental costs but also the consideration in the environmental costs of the topographical damage and the ecosystem extinction by railroad work is needed. The environment-friendly plans in choosing the locations of the railroad route and station are also suggested, and they include (1) consideration of environment protection area, residential zone, and region with scenic beauty, (2) application of the existing railroad route and station, and (3) railroad route parallel to another traffic facility.

• Journal of the Korean Society of Combustion
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• v.18 no.3
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• pp.54-60
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• 2013

This paper shows a general development process for aircraft gas turbine combustors. As a first step for developing the preliminary combustor design program, several combustor sizing methodologies using reference area concepts are reviewed. There are three ways to determine the reference area; 1) combustion efficiency approach, 2) pressure loss approach, 3) velocity assumption approach. The current study shows the comparisons of the calculated results of combustor reference values from the pressure loss and velocity assumption approaches. Further works are required to add iterative steps in the program using more reasonable values of pressure loss and velocities, and to evaluate the sizing results using data for actual combustor performance and sizes.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.51-58
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• 2020

Despite the recent growth of interest in molten salt reactor technology and the crucial role which heat transfer plays in the design of power reactors, specific studies on the design of heat exchangers for the Molten Salt Fast Reactor have not yet been performed. In this work we deliver a preliminary but quantitative analysis of the intermediate heat exchangers, based on reference design data from the SAMOFAR H2020-Euratom project. Two different promising reference technologies are selected for study thanks to their compactness features, the Printed Circuit and the Helical Coil heat exchangers. We present preliminary design results for each technology, based on simplified design tools. Results highlight the limiting effects of the compactness constraints imposed on the fuel salt inventory and the allowed size. Large pressure drops on both flow sides are to be expected, with negative consequences on pumping power and natural circulation capabilities. The small size required for the flow channels also represents possible fabrication issues and safety concerns regarding channel blockage.

• Journal of the Korea Society of Computer and Information
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• v.23 no.1
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• pp.139-145
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• 2018

This paper recommends flipped learning as a method to improve the learning abilities and the level of software utilization when it comes to using computers in children education institutes. Flipped learning enables a class fully making use of the up-to-date multimedia-related technology. Especially, flipped learning leads a participation-oriented class rather than lecture-based ones. Young child's teachers can, not only improve their capabilities to utilize multimedia, but also manage classes that follow the trend of the fourth industrial revolution. Therefore, this paper introduces the importance of media education when it comes to training preliminary teachers and suggests a flipped learning curriculum. This paper finds significance in future efficient education for raising creative and integrated thinking children.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.85-96
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• 2001

The objective of this study is to develop the water spraying which can effectively by applied to the control or suppression of the fugitive dust generated from the scrap metal handling area at the Port of Inchon. As a first step toward this goal, we carried out some preliminary analyses on the chemical composition, physical shape, and particle size distribution of the sample dust. Next, to quantitatively investigate the effect of adding surfactants to the spraying water on the wettability of the sample dust, the Standard Sink Test was carried out for four different surfactants and at six different concentrations using the surfactants considered in this study. Results of from the preliminary analysis indicated that the main chemical component consisting of the sample dust is Goethite(FeO(OH)) and that the particles smaller than 10 ${\mu}{\textrm}{m}$ in geometric diameter occupy about 36% of the sample dust in mass. This result implies that the fugitive dust generated from the scrap metal handling area at the Port of Inchon should affect the environment nearby more than we have expected. This is because of relatively large mass percentage of the small metal particles less than 10${\mu}{\textrm}{m}$ in geometric diameter, what we may call respirable particles. As for the results of the Standard Sink Test, higher surfactant concentration tends to result in the higher wettability of the sample dust for the surfactants considered in this study, which in turn ensures the high particle collection efficiency of the droplets generated from the water spraying system. Based upon this preliminary results, studies to develop more sophisticated scaled model for dynamic test in underway and the effort to find the best surfactants as well as the optimum operating conditions are being made at the same time.

• Korean Journal of Childcare and Education
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• v.7 no.2
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• pp.115-135
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• 2011

The purpose of this study was to developing a cooperative learning model utilize storytelling technique to the Preliminary childhood teachers whose learning was in order to improve ability and collaboration of making relationships a teams members by the cooperative learning which was performed on the basis of the confidence after understanding themselves and others. To achieve the purpose, the study was performed by dividing into two stages. First, the draft of storytelling based cooperative learning model was proposed by performing a literature survey and a case study. Second, the draft model was applied to the actual work. And the draft was modified and developed to the final model on the basis of the draft model's strenth and implemented to 39 students who were the sophomore of child care education department and enrolled the profession class of at B college P city for 8 weeks. From the implementation result of the model, it was obtained that there was the positive reaction on applying storytelling technique to the beginning stage of cooperative learning. And adding of 'Re-constitution role sharing team' step in the original steps was suggested. In the end, this model was modified and issued based on the research result. The researchers proposed a cooperative learning model storytelling based for Preliminary childhood teachers which consists 6 phases : (1) understanding cooperative learning (2) Building the team and role sharing team (3) theme setting and theme structuralization (4) Re-constitution role sharing team (5) announcement of the results and evaluating (6) reflection of general.