• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.2
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• pp.101-111
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• 2012

In the ALC(Autoclaved lightweight concrete) manufacturing process, if the pre-cured semi-cake is removed after proper time is passed, it will be hard to retain the moisture and be easily cracked. Therefore, in this research, we took the research by multiple regression analysis to find relationship between variables for the prediction the hardness that is the control standard of the removal time. We study the relationship between Independent variables such as the V/T(Vibration Time), V/T movement, expansion height, curing time, placing temperature, Rising and C/S ratio and the Dependent variables, the hardness by multiple regression analysis. In this study, first, we calculated regression equation by the regression analysis, then we tried phased regression analysis, best subset regression analysis and residual analysis. At last, we could verify curing time, placing temperature, Rising and C/S ratio influence to the hardness by the estimated regression equation.

• Journal of Digital Convergence
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• v.11 no.9
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• pp.103-111
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• 2013

As the demand-oriented management has been getting important in Supply Chain Management (SCM), various forecasting methods have been suggested including regression analyses. However, dependency structures among variables have been captured by a correlation coefficient, only. It results in inaccurate demand predictions. This paper suggests a new and effective forecasting modeling framework using student's t-copula function. In order to show overall modeling procedures framework, heavy tail typed numerical data and its copula estimations are provided. The suggested methodology can contribute to decrease the bullwhip effect and to stabilize volatile environment in a supply chain network.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.153-153
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• 2012

기후변화는 강우량, 기온, 해수면온도 등 많은 수문기상학적 요소에 영향을 끼치고 있으며 이러한 영향에 대한 연구가 활발하게 진행되고 있다. 그 중에서도 수공구조물의 설계에 직접적으로 영향을 끼치는 강우특성에 대한 연구는 기후변화로 야기되는 강우의 비정상성(non-stationary)을 중심으로 이루어지고 있다. 현재 수문설계량은 강우량의 빈도해석을 통해 산정되는데, 이러한 빈도해석은 기본적으로 연최대강우자료의 정상성(stationary)과 독립성(independent)을 가정하고 이루어진다. 그러나 기후변화로 연최대강우자료에 경향성이나 변동성이 나타남에 따라 경향성과 변동성을 고려할 수 있는 빈도해석 기법의 개발에 대한 필요성이 증가하고, 실제로 2000년대에 들어서면서부터 우리나라뿐만 아니라 전 세계적으로 이루어지고 있다. 연최대강우자료의 정상성을 판단하기 위해 강우자료에 대한 경향성 분석을 수행하게 되는데, 경향성 분석을 위해 다양한 통계적 기법들이 적용되고 있다. 그러나 현재 경향성 분석방법의 적용에 대한 뚜렷한 기준이 없어 여러 가지의 경향성 분석 방법을 적용하여 다수의 분석방법별 결과를 종합하여 경향성 유무를 판단하고 있는 실정이며, 동일자료에 대해서도 연구에 따라 다른 결과가 나타나고 있다. 따라서 본 연구에서는 경향성 분석방법의 기각력을 비교검토하여 경향성 분석방법의 적용에 필요한 기준을 제시하고자 한다. 이를 위해 경향성 분석을 위해 널리 사용되고 있는 t-test, Mann-Kendall test, Hotelling-Pabst test를 비교하고자 한다. 여기에서 t-test는 매개변수를 사용하는 매개변수적 방법이고, Mann-Kendall test와 Hotelling-Pabst test는 비매개변수적 방법이다. 귀무가설의 경우 t-test는 경향성이 없다고 가정하고 있는데 반해, Mann-Kendall test와 Hotelling-Pabst test는 경향성이 있다고 가정하고 있다. 기각력 검토를 위해서는 Monte Carlo simulation을 이용하였다.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.31-36
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• 2021

In order to understand the age and growth characteristics of Pacific anchovy, Engraulis japonicus, the 506 otoliths of individuals collected in the southern waters of Korea in 2004 were analyzed. Monthly age of anchovies was estimated based on the age determined through the year rings and their collection date. The growth parameters obtained using the monthly folk lengths were a theoretical maximum body length of 132.9 mm, a growth coefficient of 0.1079/month and a theoretical age of 0.0262 month when the fork length is zero. The growth equation of von Bertalanffy presented by the growth parameters was L_t=132.9(1-e^{-0.1079(t-1.0262)}). The estimation of growth parameters based on the monthly age established through year ring and collection date was deemed appropriate for understanding the growth characteristics of anchovies.

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.140-152
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• 2020

This study analyzed the satisfaction and utilization of the institutional applications used by child-education institutions from a parent's perspective. The research target is a parent who enlisted their children in private kindergarten institution located in Gyeong-gi province and final research outcomes are 443 in total. The difference in satisfaction and utilization have been identified with demographic descriptive statistics, students t-test, and F-test statistics analysis method. First, the result of T-test on the difference in satisfaction and utilization based on parents' employment status shows that statistically significant difference was found in convenience from overall satisfaction, communication from overall utilization and child-parent relationship. Second, the F-test of differences in satisfaction and utilization showed a statistically significant difference in education utilization variables, with all variables in educational background and motivation. In terms of utilization, parents' educational background and overall utilization, and children's age were confirmed to have significant differences in communication, children's relationship, and motivation in basic life. Third, the result of multiple regression analysis shows that all predictors, including ease of use, communication, and satisfaction with educational activities, have a statistically significant impact on utilization standard variables, relative contributions showed the highest level of communication satisfaction. Therefore this paper implicates that institutional applications can maximize educational effectiveness by checking the applicability of active communication and educational activities with parents and actively communicating with parents in early childhood through various educational content applications.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.505-512
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• 2021

This study is to strengthen the competitiveness of 5-star hotel restaurants in Seoul, and the paired sample t-test was used. As a result of the study, first, the importance variables of hotel restaurants were measured as high variables such as'taste and quality of food(4.30)' and'diversity of menus(4.17)'. Second, the variables satisfied by customers visiting hotel restaurants were 'quantity of food(3.86)', 'taste and quality of food(3.78)', and 'diversity of menus(3.75)', etc. were surveyed. Third, as a result of IPA analysis, the variables in the first quadrant were the restaurant staff's expertise, cleanliness of the restaurant, the taste and quality of the food, the variety of menus, rapid service, food plating, the amount of food served, and the atmosphere of the restaurant. External environment, etc. were derived. In the second quadrant, cleanliness of restaurant tableware, freshness of food, and restaurant view were investigated. In the third quadrant, the reputation, restaurant toilet cleanliness, table cleanliness, parking facilities, transportation and convenience, etc. belong to this. Finally, variables belonging to the fourth quadrant were investigated such as reasonable price, cost-effectiveness and affordability, friendliness of restaurant staff, clothing and appearance of restaurant staff, and restaurant interior.

• Sleep Medicine and Psychophysiology
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• v.24 no.1
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• pp.32-37
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• 2017

Objectives: A supine sleep position increases sleep apneas compared to non-supine positions in obstructive sleep apnea syndrome (OSAS). However, supine position time (SPT) is not highly associated with apnea-hypopnea index (AHI) in OSAS. We evaluated the correlation among sleep-related variables and SPT in OSAS. Methods: A total of 365 men with OSAS were enrolled in this study. We analyzed how SPT was correlated with demographic data, sleep structure-related variables, OSAS-related variables and heart rate variability (HRV). Multiple linear regression analysis was conducted to investigate the factors that affected SPT. Results: SPT had the most significant correlation with total sleep time (TST ; r = 0.443, p < 0.001), followed by sleep efficiency (SE ; r = 0.300, p < 0.001). Snoring time (r = 0.238, p < 0.001), time at < 90% SpO2 (r = 0.188, p < 0.001), apnea-hypopnea index (AHI ; r = 0.180, p = 0.001) and oxygen desaturation index (ODI ; r = 0.149, p = 0.004) were significantly correlated with SPT. Multiple regression analysis revealed that TST (t = 7.781, p < 0.001), snoring time (t = 3.794, p < 0.001), AHI (t = 3.768, p < 0.001) and NN50 count (t = 1.993, p = 0.047) were associated with SPT. Conclusion: SPT was more highly associated with sleep structure-related parameters than OSAS-related variables. SPT was correlated with TST, SE, AHI, snoring time and NN50 count. This suggests that SPT is likely to be determined by sleep structure, HRV and the severity of OSAS.

• Geotechnical Engineering
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• v.13 no.3
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• pp.63-76
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• 1997

To investigate the engineering characteristics of crushed rockfill material, the large-scaled triaxial tests have been carried out, The rpckfill is made from the greywacke, and the 3 parallel gradations with different maximum particle size(dmu=38.1mm, 25.4mm and 19.1mm) were designed for the test. The dimension of the specimen is 300mm in diameter and 600mm in height, and the applied confining stress varied from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$. The test results show that the influence of the maximum particle size on the stress -strain r$51.6^{\circ}\; to\; 40.5^{\circ}$ when the confining stress increases from 5t/$51.6^{\circ}$ to 60t/$51.6^{\circ}$ The hyperbolic parameter values estimated from the test result for rockfill are much different from the recommended values by Duncan et. at(1980) for GW and GP material, especially in the $\phi$ ad K-values.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.431-438
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• 2017

The purpose of the study was to identify the factors on Gatekeeper behavior of adolescents for suicide prevention. The participants were five high school students from D metropolitan city. The collected data were analysed using t-test, ANOVA, Multiple regression with SPSS 21.0 program. In the results of the study, Gatekeeper behavior showed significant difference by gender(t=2.85, p=.005), type of school(t=-2.81, p=.006), experience of significant others' suicide(t=-2.09, p=.038). Gatekeeper behavior had a positive relationship with the perception toward suicide prevention(r=.23, p=.006) and the knowledge about suicide prevention(r=.42, p<.001). In regression analysis, significant influencing factors on Gatekeeper behavior were the perception toward suicide prevention (${\beta}=.20$, p=.006) and the knowledge about suicide prevention(${\beta}=.35$, p<.001), and these variables showed 24.3% of variance. Therefore, it need to develop the intervention for improving positive perception and active knowledge about suicide prevention in adolescents. In addition, future study to identify various predictable variables is needed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.144-152
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• 2011

The existing underground trenchless methods use reinforcing rod in steel tube to obtain structural stiffness. However, there are some problems such as inconvenience of work and expensive material fee which are resulted from limited working space and reinforcing work. To resolve these problems, a new trenchless method, namely P.S.T method (Prestressed Segment Tunnel Method), is developed which uses joint to connect the steel segment and form erection structure in underground construction. Further, installing strands for prestressing. In order to evaluate the flexural capacity of the P.S.T method structure, experiment was conducted. The parameters considered in the experiment are the span-to-depth ratio, diameter of steel tube at corner, prestressing force and welding of joint. Altogether examining the flexural behavior, the effect of deflection in structure according to different parameters has also been analysised.