• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.2
• /
• pp.112-121
• /
• 2013

The calibration of resistance factor in reliability theory for limit state design of gravel compaction piles (GCP) requires a reliable estimate of ultimate bearing capacity. The static load test is commonly used in geotechnical engineering practice to predict the ultimate bearing capacity. Many graphical methods are specified in the design standard to define the ultimate bearing capacity based on the load-settlement curve. However, it has some disadvantages to ensure reliability to obtain an uniform ultimate load depend on engineering judgement. In this study, a well-fitting nonlinear regression model is proposed to estimate the ultimate bearing capacity, for which a nonlinear regression analysis is applied to estimate the ultimate bearing capacity of GCP and the results are compared with those calculated using previous graphical method. Affect the resistance factor of the estimate method were analyzed. To provide a database in the development of limit state design, the load test conditions for predicting the ultimate bearing capacity from static load test are examined.

• The Journal of Engineering Geology
• /
• v.18 no.1
• /
• pp.27-36
• /
• 2008

To derive easily the coefficient of permeability from several other soil properties, the estimation model of coefficient of permeability was proposed using linear regression analysis. The coefficient of permeability is one of the major factors to evaluate the soil characteristics. The study area is located in Kangwon-do Pyeongchang-gun Jinbu-Myeon. Soil samples of 45 spots were taken from the study area and various soil tests were carried out in laboratory. After selecting the soil factor influenced by the coefficient of permeability through the correlation analysis, the estimation model of coefficient of permeability was developed using the linear regression analysis between the selected soil factor and the coefficient of permeability from permeability test. Also, the estimation model of coefficient of permeability was compared with the results from permeability test and empirical equation, and the suitability of proposed model was proved. As the result of correlation analysis between various soil factors and the coefficient of permeability using SPSS(statistical package for the social sciences), the largest influence factor of coefficient of permeability were the effective grain size, porosity and dry unit weight. The coefficient of permeability calculated from the proposed model was similar to that resulted from permeability test. Therefore, the proposed model can be used in case of estimating the coefficient of permeability at the same soil condition like study area.

• Korean Journal of Plant Resources
• /
• v.23 no.2
• /
• pp.172-178
• /
• 2010

This study was carried out to investigate abiotic and biotic environmental factors affecting homoharringtonine (HHT) contents of Cephalotaxus koreana, whereby, to provide basic information of high value-added industry production of HHT as a promising anti-cancer agent. For correlation between abiotic environmental factors (soil moisture, soil pH, habitat density and temperature) and HHT contents, the contents were highly correlated with soil moisture (0.77) and soil pH (-0.68). For multiple regression analysis of relationship between abiotic environmental factors (soil moisture and soil pH) and HHT contents, soil moisture appeared to be strongly affecting the contents relatively due to being significant at only its regression coefficient ($26.48^{***}$). For the effect of biotic environmental factors (damage index) affecting HHT contents, the contents was quadratic with equation of $H=278.23+1242D-398.87D^2$, also, damage index had strong effect on the contents. Finally, for the result of the most influencing an environmental factor on HHT contents, both damage index and soil moisture were suitable in second polynomial regression, also, damage index ($R^2=0.73^{***}$) was turned out to be more influencing factor than soil moisture ($R^2=0.67^{**}$) on HHT contents relatively. Therefore, we predict that HHT contents in the trees of Cephalotaxus koreana is produced as a chemical defense mechanism triggered by a stress-related damage of fungi or insects.

• The Journal of Engineering Geology
• /
• v.31 no.4
• /
• pp.701-718
• /
• 2021

Geological field surveys and a series of laboratory tests were conducted to obtain data related to landslides in Sancheok-myeon, Chungju-si, Chungcheongbuk-do, South Korea where many landslides occurred in the summer of 2020. The magnitudes of various factors' influence on landslide occurrence were evaluated using logistic regression analysis and an artificial neural network. Undisturbed specimens were sampled according to landslide occurrence, and dynamic cone penetration testing measured the depth of the soil layer during geological field surveys. Laboratory tests were performed following the standards of ASTM International. To solve the problem of multicollinearity, the variation inflation factor was calculated for all factors related to landslides, and then nine factors (shear strength, lithology, saturated water content, specific gravity, hydraulic conductivity, USCS, slope angle, and elevation) were determined as influential factors for consideration by machine learning techniques. Minimum-maximum normalization compared factors directly with each other. Logistic regression analysis identified soil depth, slope angle, saturated water content, and shear strength as having the greatest influence (in that order) on the occurrence of landslides. Artificial neural network analysis ranked factors by greatest influence in the order of slope angle, soil depth, saturated water content, and shear strength. Arithmetically averaging the effectiveness of both analyses found slope angle, soil depth, saturated water content, and shear strength as the top four factors. The sum of their effectiveness was ~70%.

• Journal of Community Nutrition
• /
• v.4 no.2
• /
• pp.90-98
• /
• 2002

This study was performed to examine the dietary and BMI change of Koreans after moving to America and to identify the factors influencing changes of BMI. The subjects were 192 Korean-Americans (men : 86, women : 106) residing in the eastern area of the U.S.A. 1) subjects reported significantly increased consumption frequency in American foods like, low fat milk(p<0.001), cold cereals (p<0.001), whole wheat bread(p<0.001), hamburger(only in males p<0.01) and pizza(only in males p<0.01). Whereas significantly decreased consumption frequency in fish (p<0.05), cooked vegetables(p<0.001), kimchi(p< 0.001) and cooked rice (p<0.001) were reported. 2) It was reported that weight, accordingly BMI were significantly increased (p<0.01). The smoking habit score was significantly decreased for males (p<0.05). 3) Multiple linear regression analysis for BMI change showed that education years in Korea was the most prominent negative factor(p<0.001) in predicting BMI change in America. Elevated frequencies of alcohol, chicken and soft drink in America were also associated with greater increase of BMI. When the length of residence (increase of age) was included in regression model, the increase of age was the most significant factor (p<0.001). Changes of chicken and soda scores were other significant factors.

• Korean Chemical Engineering Research
• /
• v.47 no.5
• /
• pp.599-607
• /
• 2009

This study was conducted to derive the five correlations which could predict specific gravity(or heating value), compression factor, density, etc., if we know heating value or specific gravity only. To make a sufficient number of raw data for regression, SGERG EOS was modified into equation of heating value. Based on these raw data, five correlations were obtained and the uncertainties of the correlations were evaluated. The results showed that the uncertainties were near 0.1% in most conditions of natural gas and so the correlations could be used in natural gas industry and academic fields.

• Journal of Families and Better Life
• /
• v.25 no.6
• /
• pp.121-131
• /
• 2007

The purpose of this study was first to reveal the factors of time management behaviors of college students. The second purpose was to examine the effects of those factors on the satisfaction of time management. The data were collected from 400 college students in Seoul by a self-administered questionnaire. Frequencies, Cronbach's alpha, Factor analysis, Pearson's correlation analysis and Multiple linear regression were conducted by SPSS WIN12.0. The major findings were as follows. First, factor analysis of 20 items on the time management behaviors related questions revealed six factors: establishment of standards, reality, overlapping, checking, adjusting and facilitating. Second, many factors such as facilitating, establishment of standards, reality, overlapping were significant in the regression analyses for the satisfaction of time management. Especially, establishment of standards and facilitating had high levels of effort on the satisfaction of time management. In combination, these results suggest that establishment of standards and facilitating are very important factors for high satisfaction of time management.

• Journal of the Ergonomics Society of Korea
• /
• v.31 no.5
• /
• pp.695-704
• /
• 2012

Objective: The purpose of this study was to investigate major factors influencing adoption of smartphone to promote its use by older adults. Background: Despite increasing proportion of elderly people and elderly market, the proportion of elderly smartphone user is still relatively small compared to whole smartphone users. Thus, we need to find out major factors influencing adoption of smartphone to increase proportion of elderly smartphone users. Method: Seven major factors were extracted from 36 survey questions using factor analysis. Regression analysis was also applied to determine specific factors affecting intention of use based on user versus non-user of smartphone, age, gender, and educational background. Results: As results of factor analysis and regression analysis, major factors influencing adoption of smartphone for elderly users were significantly different according to gender, age, educational background based on smartphone users or non-users. Conclusion: The result of this study identified major factors influencing adoption of smartphone for the elderly and provided basic information related to adoption of smartphone according to elderly people's characteristics. Consequently, we can expect to reduce the information gap and to improve quality of life for the elderly. Application: The development and marketing strategy could be applied differently based on the factors influencing adoption of smartphone. It is also possible to develop a prediction model for smartphone adoption according to elderly users' characteristics.

• Korean Journal of Agricultural Science
• /
• v.44 no.4
• /
• pp.620-635
• /
• 2017

This study was intended to identify the main factors responsible for the decline in purchase of imported agricultural and fish products after Japan's nuclear power plant accident in 2011 and to compare the effects on imported agricultural produce and imported fish products. Logit model and multiple regression model analyses were performed using consumers' survey data. Psychological and qualitative factors reflecting consumers' food safety awareness and purchasing preferences, which were extracted by Factor analysis, were included as the models' explanatory variables, along with socio-demographic and economic factors. The Logit estimation showed aged, married, and low-income households had significantly higher probability of reducing their purchases of imported agricultural and fish products. However, the multiple regression results pointed out that the actual rate of decrease of imported agricultural and fish products purchases were more significantly affected by non-socio demographic factors such as past experience of purchasing imported agricultural and fish products, future intention to purchasing Japanese agricultural and fish products, and the ratio of imported to domestic agricultural and fish products before the nuclear accident, as well as consumers' feeling of food insecurity and their purchasing preferences. Moreover, the results showed that Korean consumers have reacted more sensitively to the decline in imported fish products than imported agricultural produce after the nuclear accident based on the marginal effects of various socio-demographic and economic factors.

• Journal of The Korean Digital Architecture Interior Association
• /
• v.13 no.3
• /
• pp.15-23
• /
• 2013

As a succeeding analysis on the variables' significance to 'Quality of Life(QOL)'(Kim, Dong-Yoon, 2012a), which has a purpose of trying to enhance the intersubjectiveness by means of quantitive methods to find the factors on the QOL, this study aims at finding the time serial change in the deciding factors to deepen the related researches on the theme. Using the similar statistical methods such as multiple regression and factor analysis for "2012 Seoul Survey" this study shows two similar points and one differentia. The similarities include the fact that five subcategories of happiness have relative statistical importance in the order of (1)financial condition, (2)health condition, (3)social activities, (4)community relationship and (5)family life and the fact that the five subcategories are conceptually different from the 5 deciding factors, which means the possibility to improve the survey design. And the difference is the 5 factors such as (1) social trust - amenities, (2)cultural life, (3)social indiscrimination - hope for elevation, (4)sharing - giving and (5)community spirit which are largely different from preceding study. Although only the first two factors have statistical significance this result has a implication that they reflect the new paradigm of social capital and the essential necessity of human survival; sharing-community-culture.