• Title/Summary/Keyword: t-square

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Evaluation of the Closed-type Sprinkler Head Activation Time (밀폐형 스프링클러 헤드의 동작시간 평가)

  • Moon-Hak, Jee;Sung-Yull, Hong
    • Fire Science and Engineering
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    • v.18 no.3
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    • pp.1-8
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    • 2004
  • As a predominant active fire suppression method, closed-type sprinkler systems are used for the purpose of fire control and suppression at the nuclear power plants as well as the industrial facilities. It goes without saying that the proper selection of the system guarantees the adequate actuation of the thermal device. Consequently, the appropriate evaluation should be executed for the thermal behavior with the theoretical and empirical approach. For this purpose, the comparison of activation time for the fusible-link type sprinkler head with the simplified fire case and t-square fire growth case was evaluated. At this paper, the comparison output was presented with the tendency of thermal behavior. In addition, we issued some technical comments for the most appropriate equation in case of the estimation of the sprinkler head activation time. We also raised some idea that should be incorporated for the usage of the t-square equation for the realistic application in the field of the performance-base fire protection approach.

Study on the Characteristics of Drawbead Forces in Automotive Stamping Dies (자동차 스템핑 금형의 드로우비드력 특성에 관한 연구)

  • Moon, S.J.;Keum, Y.T.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.431-433
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    • 2007
  • The drawbeads, which is used for controlling the flow of the sheet by imposing the tension and for preventing the springback in the sheet metal forming process, affects a lot the formability because of the differences in the restraint and opening forces according to the drawbead shapes and dimensions. In this study, the experimental device enabling to measure the drawbead restraining and opening forces was manufactured and the drawing forces of circular, square, and step drawbeads are measured. The drawbead restraining and opening forces of a circular drawbead are increased as its drawbead height is increased. Similarly, those of a square drawbead are increased as its height is increased and shoulder radii decreased. Also, those of a step drawbead are increased as its height and difference in their heights are increased.

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Analysis of the wind loading of square cylinders using covariance proper transformation

  • de Grenet, Enrico T.;Ricciardelli, Francesco
    • Wind and Structures
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    • v.7 no.2
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    • pp.71-88
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    • 2004
  • In this paper the capacity of Covariance Proper Transformation (CPT) analyses to provide information about the wind loading mechanisms of bluff bodies is investigated through the application to square cylinders. CPT is applied to the fluctuating pressure distributions on a single cylinder, as well as on a pair of cylinders in the tandem and side by side arrangements, with different separations. Both smooth and turbulent flow conditions are considered. First, through the analysis of the contributions of each CPT mode to the total fluctuating aerodynamic forces, a correspondence between modes and aerodynamic components is sought, which is then verified through examination of the mode shapes. When a correspondence between modes and aerodynamic components is found, an attempt is made to separate the different frequency contributions to the aerodynamic forces, provided by each mode. From the analyses it emerges that (a) in most cases each mode is associated to one single force component, that (b) retaining a limited number of modes allows reproducing the aerodynamic forces with a rather good accuracy, and that (c) each mode is mainly associated with one frequency of excitation.

Analysis for Water tank model simulation of parallel plate electrodes (병렬판상전극의 수조모델 시뮬레이션 해석)

  • Koh, Hee-Seog;Kim, Sung-Sam;Lee, Chung-Sik;Choi, Jong-Kyu;Ryoo, Hee-Suk
    • Proceedings of the KIEE Conference
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    • 2003.07a
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    • pp.280-282
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    • 2003
  • In this paper we tried to analyze through the water tank model to solve these kinds of problems about the square plate earth electrode using general facilities with being compared with the theory formula announced before. The square plate earth electrode that haven't investigated so far is analyzed by being based on laid rod electrode. And the each kind of calculation model was investigated with the experiment of water tank. An experiment of the vertical square Plate electrode about laying depth in the center of the surface of the water has already done with the practical models that have different forms of electrodes.

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Studies on T-Shaped composite columns consist of multi separate concrete-filled square tubular steel sections under eccentric axial load

  • Rong, Bin;You, Guangchao;Zhang, Ruoyu;Feng, Changxi;Liu, Rui
    • Steel and Composite Structures
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    • v.22 no.2
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    • pp.217-234
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    • 2016
  • In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

Identification of Uncertainty in Fitting Rating Curve with Bayesian Regression (베이지안 회귀분석을 이용한 수위-유량 관계곡선의 불확실성 분석)

  • Kim, Sang-Ug;Lee, Kil-Seong
    • Journal of Korea Water Resources Association
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    • v.41 no.9
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    • pp.943-958
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    • 2008
  • This study employs Bayesian regression analysis for fitting discharge rating curves. The parameter estimates using the Bayesian regression analysis were compared to ordinary least square method using the t-distribution. In these comparisons, the mean values from the t-distribution and the Bayesian regression are not significantly different. However, the difference between upper and lower limits are remarkably reduced with the Bayesian regression. Therefore, from the point of view of uncertainty analysis, the Bayesian regression is more attractive than the conventional method based on a t-distribution because the data size at the site of interest is typically insufficient to estimate the parameters in rating curve. The merits and demerits of the two types of estimation methods are analyzed through the statistical simulation considering heteroscedasticity. The validation of the Bayesian regression is also performed using real stage-discharge data which were observed at 5 gauges on the Anyangcheon basin. Because the true parameters at 5 gauges are unknown, the quantitative accuracy of the Bayesian regression can not be assessed. However, it can be suggested that the uncertainty in rating curves at 5 gauges be reduced by Bayesian regression.

Growth curve estimates for wither height, hip height, and body length of Hanwoo steers (Bos taurus coreanae)

  • Park, Hu-Rak;Eum, Seung-Hoon;Roh, Seung-Hee;Sun, Du-Won;Seo, Jakyeom;Cho, Seong-Keun;Lee, Jung-Gyu;Kim, Byeong-Woo
    • Korean Journal of Agricultural Science
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    • v.44 no.3
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    • pp.384-391
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    • 2017
  • Growth curves in Hanwoo steers were estimated by Gompertz, Von Bertalanffy, Logistic, and Brody nonlinear models using growth data collected by the Hanwoo Improvement Center from a total of 6,973 Hanwoo (Bos taurus coreanae) steers 6 to 24 months old that were born between 1996 and 2015. The data included three parameters: A, mature size of body measurement; b, growth ratio; and, k, intrinsic growth rate. Nonlinear regression equations for wither height according to Gompertz, Von Bertalanffy, Logistic, and Brody models were $Y_t=144.7e^{-0.5869e^{-0.00301t}}$, $Y_t=145.3(1-0.1816e^{-0.00284t})^3$, $Y_t=143.1(1+0.7356e^{-0.00352t})^{-1}$, and $Y_t=146.8(1+0.4700e^{-0.00249t})^1$, respectively, while those for hip height were $Y_t=144.5e^{-0.5549e^{-0.00312t}}$, $Y_t=145.0(1-0.1724e^{-0.00295t})^3$, $Y_t=143.1(1+0.6863e^{-0.00360t})^{-1}$, and $Y_t=146.2(1+0.4501e^{-0.00263t})^1$, respectively. Equations for body length $Y_t=174.1e^{-0.8342e^{-0.00289t}}$, $Y_t=175.8(1-0.2500e^{-0.00265t})^3$, $Y_t=170.0(1+1.1548e^{-0.00363t})^{-1}$, and $Y_t=180.3(1+0.6077e^{-0.00215t})^1$, respectively, for the same models. Among the four models, the Brody model resulted in the lowest mean square error, with mean square errors of 31.79, 30.57, and 42.13, respectively, for wither height, hip height, and body length. Also, an estimated birth wither height, birth hip height, and birth body length (77.98, 80.57, and 70.97 cm, respectively) were lower in the Brody model than in other models. An inflection point was not observed during the growth phase of Hanwoo steer according to the growth curves calculated using Gompertz, Von Bertalanffy, and Logistic models. Based on the results, we concluded that the regression equation using the Brody model was the most appropriate among the four growth models. To obtain more accurate parameters, however, using data from a wider production period (from birth to shipping) would be required, and the development of a suitable model for body conformation traits would be needed.

Effects of Convergence-based Simulation Education on the Problem Solving Ability, Self-Efficacy and Performance Confidence of Core Fundamental Nursing Skill for Nursing Students (융합시뮬레이션 교육이 간호학생의 문제해결능력, 자기효능감 및 핵심기본간호술 수행자신감에 미치는 효과)

  • Lee, Hyun-Jung
    • Journal of Convergence for Information Technology
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    • v.10 no.1
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    • pp.44-50
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    • 2020
  • This study was performed to examine the effect of convergence-based simulation education on the problem solving ability and self-efficacy and confidence of core fundamental nursing skill performance for nursing students. A non equivalent control group post-test only design was utilized(experimental group(n=97), control group (n=87)). Data were analyzed using independent t-test, Chi-square test and Pearson's correlation. The scores of the problem solving ability(t=-2.04, p=.043) and confidence of core fundamental nursing skill performance(t=5.31, p<.001) were higher than those of the experimental group than control group. It is necessary to find ways to iterative and convergent research that verifies the continuous development and effectiveness of various courses.

A Convergence Study on Effects of Gratitude Diary Writing by Smart Device on Self-Esteem and Internal & External Locus of Control in Adolescent (스마트 기기를 이용한 감사의 일기쓰기가 청소년의 자아존중감과 내외 통제성에 미치는 영향에 대한 융복합 연구)

  • Won, Su Jin
    • Journal of Convergence for Information Technology
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    • v.11 no.10
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    • pp.68-73
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    • 2021
  • This study was to identify the effects of using Gratitude Diary Writing on self-esteem and internal-external locus of control to adolescent. A randomized controlled experimental design was used. There were 20 participants in the experimental group, and 19 in the control group. Data were analyzed using Chi-square test, Fisher's exact test, t-test. The results of self-esteem(t=5.142, p=<.001) and internal-external locus of control(t=5.821 p=<.001)l showed statistically significant differences between the two groups. Using thank journal writing is effective in improving adolescents self-esteem and internal-external locus of control. If the gratitude diary writing effect of gratitude is verified by selecting a wide sample, it is expected that it will be helpful for generalize activities.

Comparison of the Power of Bootstrap Two-Sample Test and Wilcoxon Rank Sum Test for Positively Skewed Population

  • Heo, Sunyeong
    • Journal of Integrative Natural Science
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    • v.15 no.1
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    • pp.9-18
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    • 2022
  • This research examines the power of bootstrap two-sample test, and compares it with the powers of two-sample t-test and Wilcoxon rank sum test, through simulation. For simulation work, a positively skewed and heavy tailed distribution was selected as a population distribution, the chi-square distributions with three degrees of freedom, χ23. For two independent samples, the fist sample was selected from χ23. The second sample was selected independently from the same χ23 as the first sample, and calculated d+ax for each sampled value x, a randomly selected value from χ23. The d in d+ax has from 0 to 5 by 0.5 interval, and the a has from 1.0 to 1.5 by 0.1 interval. The powers of three methods were evaluated for the sample sizes 10,20,30,40,50. The null hypothesis was the two population medians being equal for Bootstrap two-sample test and Wilcoxon rank sum test, and the two population means being equal for the two-sample t-test. The powers were obtained using r program language; wilcox.test() in r base package for Wilcoxon rank sum test, t.test() in r base package for the two-sample t-test, boot.two.bca() in r wBoot pacakge for the bootstrap two-sample test. Simulation results show that the power of Wilcoxon rank sum test is the best for all 330 (n,a,d) combinations and the power of two-sample t-test comes next, and the power of bootstrap two-sample comes last. As the results, it can be recommended to use the classic inference methods if there are widely accepted and used methods, in terms of time, costs, sometimes power.