• 대한기계학회논문집B
• /
• 제26권1호
• /
• pp.55-65
• /
• 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.

• 한국압력기기공학회 논문집
• /
• 제4권2호
• /
• pp.1-6
• /
• 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.

• 한국지진공학회논문집
• /
• 제16권6호
• /
• pp.29-36
• /
• 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.

• 한국조리학회지
• /
• 제12권4호
• /
• pp.284-298
• /
• 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.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.1178-1183
• /
• 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.

• 한국연소학회지
• /
• 제18권3호
• /
• pp.54-60
• /
• 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
• /
• 제52권1호
• /
• pp.51-58
• /
• 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.

• 한국컴퓨터정보학회논문지
• /
• 제23권1호
• /
• pp.139-145
• /
• 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.

• 한국대기환경학회지
• /
• 제17권1호
• /
• pp.85-96
• /
• 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.

• 한국보육지원학회지
• /
• 제7권2호
• /
• pp.115-135
• /
• 2011

본 연구는 팀 구성원들과 관계를 형성하여 협동하는 능력을 길러주고, 자신과 타인에 대해 이해하고 신뢰가 바탕이 되어야 하는 예비유아교사들에게 스토리텔링 기법을 활용하여 협동학습 모형을 개발하고자 한다. 이러한 연구의 목적을 달성하기 위하여 문헌 및 사례연구를 통하여 스토리텔링기반 협동학습 모형 초안을 구안하고, 이를 현장에 적용하여 모형의 강점과 개선점을 중심으로 수정 보완하여 모형을 구안하였다. 도출된 모형의 초안은 P시 D대학 유아교육과 학생을 대상으로 6주에 걸쳐 현장적용 하였다. 그 결과, 협동학습에 대한 긍정적인 반응과 협동학습에 대한 재인식하기, 팀 구성원의 역할분담 재구성에 대한 필요성이 도출되었고, 이를 바탕으로 모형을 수정 보완하여 예비유아교사를 위한 협동학습 모형의 최종안을 구안하였다.