• Nuclear Engineering and Technology
• /
• v.26 no.1
• /
• pp.1-8
• /
• 1994

The flame speed correlation considering thermal-hydraulic phenomena under severe accidents is proposed and correction coefficients are defined. This correlation modifies the pressure dependency in Iijima-Takeno correlation and adds the steam suppression effects to it in the anticipated hydrogen and steam concentration ranges under severe accidents. The existing models of flame speed due to hydrogen combustion under severe accidents are based on the experiments which were performed merely at room temperature and atmospheric pressure. They have difficulty in predicting a accurate flame speed in a case of high temperature and pressure during severe accidents. Thus the flame structure is assumed as a prerequisite to the reliable determination of flame speed and theoretical model is developed. To examine the validity, flame speeds in various conditions calculated by this model are compared with those obtained by the calculation of the existing correlations of the codes such as improved HECTR and MAAP. Also the steam suppression ratio is quantified and the steam suppression coefficient is defined as a composition of mixture. Initial temperature and pressure dependencies are investigated and correction coefficents are determined. More experimental studies can be recommended to improve this correlation to its further works.

• Magazine of the Korea Concrete Institute
• /
• v.9 no.4
• /
• pp.155-165
• /
• 1997

Since the biggest time-dependent prestress loss of reactor containment structure is due to creep of concrete. the creep is one of important structural factors to be considered for the safety maintenance in the containment structure during design. construction and main enance. This paper is about the creep charactoristies of concrete for the reactor containment structure. In this paper, creep test was performed to show the creep characteristics of reactor containment concrete structure made of the type-V cement. Then, in order to evaluate the applicability of creep prediction equations of recently revised Korean Concrete Standard Specification(KSCE-96) and Japanes Concrete Standard Specification. ACI-209. CEB/FIP-90. and HANSEN, creep test results were compared with prediction results obtained from he equations. From the comparisons, it was shown that the equation of th KSCE-96 predicts creep for younger concrete than 1 year, better than the other equations and that all of the equations predicts creep, for older concrete than 1 year, smaller than test. From regression analysis. a creep prediction equation which effectively predicts creep of concrete due to loading after 1year was proposed.

• Nuclear Engineering and Technology
• /
• v.23 no.3
• /
• pp.328-339
• /
• 1991

A multi-purpose research reactor called KMRR has been developed by Korea Atomic Energy Research Institute(KAERI) to generate a maximum thermal output of 30 MW. As a part of thermal hydraulics study, pressure drop characteristics of the longitudinally finned fuel rod bundles were experimentally investigated in a recirculating water test loop. The present study is focused on the investigation of fin effects on pressure drop and the development of pressure drop correlation for the finned rod bundles in a wide range of flow conditions. Friction factor correlations for each design of the finned rod bundles are developed. The value of friction factor for the finned rod bundles was higher than the analytical solution (64/Re) of laminar circular channel new but became lower than the Blasius equation as Reynolds number was increased.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.477-480
• /
• 2006

본 논문에서는 한국 동해 강구항 전면해역에서 계절풍이 탁월한 3월과 태풍 우쿵(WUKONG) 내습시 8월에 수압식 파고계를 이용하여 파랑관측을 실시하였다. 관측파랑자료의 해석을 통해 관측시점에서의 계절풍 및 대풍내습시의 기상현황과 파랑과의 상호관련성, 발생파랑의 통계적 특성을 분석하였다. 그 결과에 따르면 관측기간동안 강구항 전면해역에서는 직립방파제 설계식의 관계식 $H_{max}\;=\;1.8H_S$를 초과하는 고파랑이 태풍 내습시 발생하며, 계절풍이 발달한 시기에는 약 3m 파고의 파랑이 발생하였다.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.2
• /
• pp.139-148
• /
• 2021

The purpose of this study performed to develop a tool to investigate sexual knowledge and sexual attitude of Mongolian university students, and to verify the validity and reliability of the developed tool.. The subjects of the study and data collection were conducted from December 1st to 30th, 2019 with 200 university students from U city in Mongolia. For tool verification, item analysis used content validity, composition validity, and reliability verification. The reliability of the tool was verified using the Cronbach's alpha coefficient, and the SPSS 26.0 version was used for statistical analysis. The results of the study consisted of 14 questions on sexual knowledge and 25 questions on sexual attitude of Mongolian university students. Results of this study could be used as a measurement tool for measuring sexual knowledge and sexual attitude of Mongolian university students and when applying the program.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.366-374
• /
• 2017

This study was conducted to explore the degree of female nursing student's dietary behavior, self esteem, dietary self-efficacy, life stress and the factors influencing dietary behavior of those surveyed. A total of 422 female nursing students in B, C city were surveyed. The data were collected between May 15 and 30 of 2016 and analyzed by a t-test, ANOVA, Pearson's correlation coefficients, and multiple regression analysis using SPSS WIN/21.0. The mean score of dietary behavior was $3.01{\pm}0.49$. In addition, there were significant differences in dietary behavior with respect to grade(F=4.823, p=0.008), residential type(F=6.067, p<.001), academic grade(F=3.907, p=0.021), health status(F=7.975, p<0.001), and degree of health concern(F=4.189, p=0.016). Moreover, there were negative correlations between dietary behavior and self esteem(r=-.238, p<0.001), and dietary self-efficacy(r=-0.438, p<0.001), while there was a positive correlation between dietary behavior and life stress(r=0.194, p<0.001). Regression analysis showed 26.7% of variance in female nursing student's dietary behavior can be explained by dietary self-efficacy, life stress, residental type, and degree of health concern. A follow-up survey investigating various factors influencing female nursing student's dietary behavior is needed and increased dietary behavior education and programs are required.

• Journal of Korean Society of Transportation
• /
• v.32 no.4
• /
• pp.410-420
• /
• 2014

This research suggests a new tram signal priority model which determines signal timings and tram intersection waiting time using analytical method. This model can calculate the signal timings for Early Green and Green Extension among the active tram signal priority techniques by tram detection time of upstream detector. Moreover, it can determine the tram intersection waiting time that means tram intersection travel time delay from a vantage point of tram travel. Under the active tram signal priority condition, priority phases can bring additional green time from variable green time of non-priority phases. In this study, the signal timing and tram intersection waiting time calculation model was set up using analytical methods. In case studies using an isolated intersection, this study checks tram intersection waiting time ranged 12.7 to 29.4 seconds when variable green times of non-priority phases are 44 to 10 seconds under 120 seconds of cycle length.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2005.05a
• /
• pp.47-55
• /
• 2005

Fire extinguisher, which is cost effective and easily accessible, is a very effective way of fire suppression. To keep its initial performance it needs periodical inspection and appropriate maintenance. However, many fire extinguishers of which the powder is incompletely coated deteriorates due to the moisture and leak of charge pressure after several years. Accordingly inappropriate powder replacement and pressurization has widely been doing by unqualified persons. Also, the absence of lifetime for fire extinguisher made people keep old bad fire extinguisher without precise inspection. This study specified those issues through case studies and suggested some ways for the systematic improvement.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.576-580
• /
• 2010

NRCS의 유출곡선지수 산정법(CN; Runoff Curve Number method)은 유역내의 토지 이용 및 토지 피복, 토양특성, 수문학적 조건 등을 이용하여 총 강우량으로부터 유효 유출량을 계산하는 방법으로서 이론의 간편성과 적용성으로 인하여 여러 분야에 적용되고 있다. 그러나, 유출곡선지수의 특성상 지역적인 특성에 따라 차이가 발생할 수 밖에 없음에도 국내에서는 대부분 미국 NEH(National Engineering Handbook)에서 제시한 기준을 이용하고 있는 실정이다. 이에 대하여 본 연구에서는 국내 유역의 강우-유출 특성을 반영한 유출곡선지수를 산정하고 강우에 따른 직접 유출량을 모의하기 위한 방법을 연구하였다. 이를 위하여 보청천 유역의 관측 강우-유출 자료에 Hawkins et al(1993)등이 제시한 점근 유출곡선지수방법을 적용하고 이를 국가수자원관리종합정보시스템(WAMIS)에서 제시한 값과 비교하였다. 또한 유역의 대표 유출곡선지수에 대한 회귀식을 유도하고 이를 이용하여 보청천 유역의 하계 유출을 모의하고 그 결과를 비교 분석 하였다. 연구결과 대표 유출곡선지수식을 이용한 유역의 직접유출 모의결과가 단일 유출곡선지수시의 모의결과보다 더 우수한 결과를 나타내었다.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.3
• /
• pp.13-22
• /
• 2004

In case of the lateral movement accurring at soft ground where a row of piles are installed, the crown failure at external arch zone of soil arching is firstly developed, and the cap failure at wedge zone in front of piles is lastly developed. Therefore, the lateral earth pressure acting on a row of piles due to soil movement should be calculated in each condition of crown and cap failures around piles. A theoretical equation of crown failure can be proposed using a cylindrical cavity expansion theory. The theoretical equation of crown failure is mainly affected by two factors. One is related to soil properties such as internal friction angle, cohesion and horizontal pressure, and the other is related to pile factors such as diameter, installation interval. Meanwhile, the yield range of lateral earth pressure is established in the estimation of theoretical equation based on crown and cap failures around piles. The theoretical values based on crown and cap failures are compared with the experimental values. The experimental values are located in the range proposed by theoretical values. Thus, it is confirmed that the theoretical values proposed in the study are very reasonable.