• 한국가시화정보학회지
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• 제14권3호
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• pp.46-50
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• 2016

The objective of the present study is to perform experiments for water filled cavity heated and cooled from the side at $Ra=8.5{\times}108$. This experiment can provide validation database of the standard k-${\varepsilon}$ turbulence model for single-phase turbulent natural convection which has been regarded as one of the important phenomena in nuclear safety. For the natural convection inside a cavity, temperature and velocity were obtained by thermometry and PIV (Particle Image Velocimetry) methods. These results would be used for validation of standard k-${\varepsilon}$ turbulence model.

• 한국가스학회지
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• 제16권4호
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• pp.23-31
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• 2012

밀폐 공간 내의 천연가스 공급 시스템에서 가스 누설에 따른 재난을 방지하고 보다 안전한 설계를 하기 위해서는 누출된 천연가스의 확산거동을 이해하고 예측할 수 있는 기술이 필요하다. 본 연구에서는 CFD를 사용한 해석법을 제시하고, 기 수행된 British Gas Technology Co.의 실험결과와 비교하여 타당성을 제시하였다. 노즐에서의 분출유량 2D 해석 결과는 실험결과와 2.6% 이내로 잘 일치함을 보였다. 또한, 다양한 강제 환기 조건에 따른 가스 확산 특성을 비정상상태 3차원 CFD 해석을 수행한 결과 실험결과와 정성적인 경향이 잘 일치됨을 보였다.

• 한국재료학회지
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• 제14권11호
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• pp.775-779
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• 2004

For improvement of heat dissipation performance, heat analysis is conducted on the newly designed heat sinks under two convection conditions by using computational fluid dynamics(CFD). Three types of heat sink, plate, wave and top vented wave, are used, and convection conditions are the variations of gravity direction at natural convection and of fan location at forced convection. The results of analysis showed that the heat resistances of top vented wave heat sink were $0.17^{\circ}C$/W(forced convection) and $0.48^{\circ}C$/W(natural convection). In the case of natural convection, gravity direction affected heat flow change, and protection against heat performance was superior in case of z-axis gravity direction. Under the forced convection, all the heat sinks revealed superior thermal characteristics in the fan position of z-axis rather than y-axis. In this study, it was observed that the top vented wave type heat sink showed the best ability of heat radiation comparing with the others.

• 한국소음진동공학회논문집
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• 제26권1호
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• pp.27-38
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• 2016

The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.

• 한국과학교육학회지
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• 제16권4호
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• pp.351-364
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• 1996

This study aimed at identifying the organization of contents, the level and scope, the time of study and experiment acivities in science text books by comparing and analizing the characteristics of the Elementary School Educational Curriculum in Korea, China and Japan. First, the objectives of science subject are focussed on understanding nature exactly, learning inquiry methods and developping scientific attitudes. This is very desirable in the lights of teaching students' characteristics. Second, three countries, Korea, China and japan treat the natural phenomena impartially in the formation of the contents of natural science. Especially, china threats scientic contents related to the real life themes importantly. Third, the number of concepts and pages of the natural science textbook are put in Korea. China and Japan in order. Time of study and the level scope of contents in natural science should be composed of desirable national situations. Forth, the time of experiment activities is put in Korea, Japan and china also in order.

• 한국동물학회지
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• 제20권1호
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• pp.1-8
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• 1977

1974年 安養에서 採集한 초파리의 走光性行動에 대한 人爲淘汰實驗을 행하였다. 淘汰의 結果, 第10世代까지의 走光性 및 避光系統의 遺傳率은 每世代當 2$\\sim$4%로 나타났다. 淘汰系統間의 相對交配實驗의 結果, 避光行動을 나타내는 遺傳子가 走光性遺傳子에 대하여 部分的 優性의 효과가 있음을 알았고, 그 효과는 淘汰의 後期世代에서 더욱 뚜렷하였다. 淘汰15世代後, 走光性과 避光性系統에 대하여 人爲淘汰를 中止하고 自然淘汰에 의한 遺傳子의 行動을 調査하였다. 實驗結果, 數世代以內에 最初集團의 走光性指數로 환원되었다. 이러한 현상은 自然淘汰에 의한 遺傳的復元性의 一例라고 생각된다.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.832-845
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• 2024

Reactor cavity cooling systems (RCCSs) comprising passive safety features use the atmosphere as a coolant, which cannot be lost. However, their drawback is that they are easily affected by atmospheric disturbances. To realize the commercial application of the two types of passive RCCSs, namely RCCSs based on atmospheric radiation and atmospheric natural circulation, their safety must be evaluated, that is, they must be able to remove heat from the reactor pressure vessel (RPV) surface at all times and under any condition other than under normal operating conditions. These include both expected and unexpected natural phenomena and accidents. Moreover, they must be able to eliminate the heat leakage emitted from the RPV surface during normal operation. However, utilizing all of the heat emitted from the RPV surface increases the degree of waste heat utilization. This study aims to understand the characteristics and degree of passive safety features for heat removal by comparing RCCSs based on atmospheric radiation and atmospheric natural circulation under the same conditions. It was concluded that the proposed RCCS based on atmospheric radiation has an advantage in that the temperature of the RPV could be stably maintained against disturbances in the ambient air.

• 한국가정과교육학회지
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• 제13권1호
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• pp.1-11
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• 2001

Home economics education professional knowledge consists of empirical interpretive critical science component. Thus it is imperative that the alternative research perspectives be used to gain certain knowledge for the profession of home economics education. In human inquiry and education there is a growing concern that the dominant research paradigm positivist natural science model is inadequate to address the phenomena constructed by persons. However, Home economics education has not examined and almost utilized alternative research perspectives. This review will probe research logic and resecrach methodology of qualitative inquiry within home economics education and highlight the shift from positivism to post-positivism.

• International journal of advanced smart convergence
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• 제2권2호
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• pp.7-9
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• 2013

Current physics-based simulation is an important tool in the fluid animation. However some problems require a new change to current research trends which depend only on the simulation. The ultimate goal of this project is to obtain information of flow example, analyze an example through machine learning and the novel fluid animation reconfigure without physical simulation.

• 대한의용생체공학회:의공학회지
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• 제5권1호
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• pp.33-38
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• 1984

Biological rhythms are very important phenomena to generate, grow a living thing. However, the origin of rhythms are not disclosed completely until now. Eack myocardial cell has a natural rhythm of itself, and synchronization is happened when two cells are come in contact with each other. In this research, a simple synchronization model has been proposed and studied, refering to the physiological model. The changes of the synchronization rhythms in experimental results are compared with that of the model.