• Journal of Nutrition and Health
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• v.31 no.1
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• pp.36-45
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• 1998

Dietary and other factors affecting bone density of 32 Korean healthy college women aged 19-23 years were assessed. Data for food and nutrient intake was obtained by a semiquantitiative food frequency questionnaire. Serum samples were anlayzed for total Ca, P, Ca++, PTH, calcitonin and 25-hydroxycholecalciferol , (25-OH-Vit D3) and BMDs of lumbar spine(L2-L4), femoral neck(FN), ward's triangle (WT) and trochanter(TR) were measured by an XR-series X-ray bone densitometer. Relationships between the factors and BMDs were analyzed by stepwise multiple regression analysis and Pearson's correlation coefficient(r). The results are summarized as follows. Mean daily intake of energy(86.1%), Ca(74.3%), vitamin A (53.75), Fe(49.75) and vitamin B$_2$(86.6%) were lower while other notrients incuding P(126%) were higher than the Korean RDA. The BMDs of lumbar spines and femurs ranged from 0.73g/$\textrm{cm}^2$ to 1.23g/$\textrm{cm}^2$and 0.48g/$\textrm{cm}^2$ to 1.04g/$\textrm{cm}^2$, respectively. Both protein and P intakes were inversely associated with serum total Ca. Furthermore, Ca intake as well as Ca/P ratio (Ca/P) were inversely associated with serum ionized Ca(Ca++) concentration. The intakes of protein P and Ca , however, were not significantly associated with the BMDs measured in this study. There were little association between BMDs and alcoholic beverage or caffeine consumption. The only significant association detected was a positive relationship between caffeine consumption and BMD of WT. It seemed to be noticeable that BMDs of L2-L$_4$, FN and WT were significantly inversely associated with serum P concentration. However, there was no significant association between BMDs and the levels of total Ca to Ca++ in serum. Body weight was positively associated with BMD of lumbar spine and BMI was also positively associated with BMDs of FN and WT. The subjects who had an early menarche appeared to have higher BMDs than those who had had a late mearche. According to stepwise multiple regression analysis. Menarche and BMI were stronger determinants of BMDs in the young women than was diet. P intake appeared to be a more potent dietary determinant than Ca intake. The three factors, menarche, BMI , and P intake , additionally accounted for 24% and 378% of the variance in BMDs of FN and L$_2$-L$_4$, respectively. Further investigation is necessary to determine the factors needed to increase serum P level which negatively affects. BMD in young Korean college women.

• Journal of the Korea Society for Simulation
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• v.23 no.1
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• pp.21-31
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• 2014

In this article, data mining simulation is applied to find a proper approach and results of analysis for study of variables related to organization. Also, turnover intention and organizational commitment are used as target (dependent) variables in this simulation. Classification and regression tree (CART) with ensemble methods are used in this study for simulation. Human capital corporate panel data of Korea Research Institute for Vocation Education & Training (KRIVET) is used. The panel data is collected in 2005, 2007, and 2009. Organizational commitment variables are analyzed with combined measure variables which are created after investigation of reliability and single dimensionality for multiple-item measurement details. The results of this study are as follows. First, major determinants of turnover intention are trust, communication, and talent management-oriented trend. Second, the main determining factors for organizational commitment are trust, the number of years worked, innovation, communication. CART with ensemble methods has two ensemble CART methods which are CART with Bagging and CART with Arcing. Comparing two methods, CART with Arcing (Arc-x4) extracted scenarios with very high coefficients of determination. In this study, a scenario with maximum coefficient of determinant and minimum error is obtained and practical implications are presented. Using one of data mining methods, CART with ensemble method. Also, the limitation and future research are discussed.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.1
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• pp.58-64
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• 2009

The objectives of this study were to investigate the aggregate fragmentation in wet-sieving and to evaluate the relationship between the aggregate fragmentation fractal dimension and macro-porosity of upland soils, using three different textural types of soils including Gopyeng series (Fine, Typic Hapludalfs), Gyuam series (Fine silty over coarse silty, Fluvaquentic Eutrudepts), and Jungdong series (Coarse loamy, Typic Udifluvents) located in Gyeonggi province. Undisturbed soil samples with five replicates were seasonally sampled and used for measuring water stable aggregate, macropores, and physico-chemical properties of soils. The aggregate stability in wet-sieving was digitalized as three types of fragmentation fractal dimension ($D_f$), geometric mean diameter (GMD), and mean weight diameter (MWD). $D_f$ had higher correlation with GMD than with MWD. Seasonal aggregate stability showed the highest values in summer, and decreased in the order of spring and autumn. The macroporosity had higher in topsoil, in autumn, and in ridge, than in plow pan layer, in summer, and in row, respectively. The relationship between $D_f$ and macroporosity, especially more than 99 m, showed high correlation only in soils with $D_f$ less than 3.1, which means more aggregated soils compared to soils with $D_f$ more than 3.1. Besides, in the soils with the fractal dimension less than 3.1, the power function relation between saturated hydraulic conductivity and macroporosity more than 99 m had relatively high determinant coefficient, and vice versa. Therefore, it could be thought that fragmentation fractal dimension is available for confirming macroporosity induced from aggregation.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.772-779
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• 2012

For improving performance of conical air diffuser generating fine bubble, both experimental and numerical simulation method were used. After adapting diffusers inner real scale bubble column, suitable for various diffuser submergence, the effect of diffuser submergence on oxygen transfer performance such as Oxygen Transfer Coefficient ($K_{L}a_{20}$) and Standard Oxygen Transfer Efficiency (SOTE) was investigated empirically. As flow patterns for various diffuser number and submergence were revealed throughout hydrodynamic simulation for 2-phase fluid flow of air-water, the cause of the change for oxygen transfer performance was cleared up. As results of experimental performance, $K_{L}a_{20}$ was increased slightly by 7% and SOTE was increased drastically by 39~72%, 5.6% per meter. As results of numerical analysis, air volume fraction, air and water velocity in bioreactor were increased with analogous flow tendency by increasing diffuser number. As diffuser submergence increased, air volume fraction, air and water velocity were decreased slightly. Because circulative co-flow is determinant factor for bubble diffusion and rising velocity, excessive circulation intensity can result to worsen oxygen transfer by shortening bubble retention time and amount.

• Journal of Korea Port Economic Association
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• v.28 no.1
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• pp.263-288
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• 2012

This study aims to define which factors will contribute to vitalization of Saemangeum New Port to secure international competitiveness in order to attract international shipping companies, shippers and forwarders in constructing Saemangeum New Port, and to propose subsequent implications. For research methods of the current study, a factor analysis and a decision making method of analytic hierarchy process(AHP) were used. Through precedent studies, total 11 measuring variables were selected including short entrance and exit channels, main infrastructure development project, tax cut and deregulation, and through a factor analysis, total 3 high rank evaluation factors including 'location and facilities', 'surrounding infrastructure and hydrophile property', and 'local policy and environment'. Analysis results summarizing a test of reliability of measuring variables in this study indicate that as Cronbach alpha coefficient of total 11 measuring variables were turned out to be over 0.8, it is surpassing general average 0.6, which means there is reliability.

• The Journal of Engineering Geology
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• v.18 no.2
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• pp.167-176
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• 2008

The variation characteristics of groundwater level with distance from shoreline at Jeju Island was investigated using groundwater level data monitored from 257 wells for dry season (December 1998) and wet season (July 1997), respectively. Groundwater levels of the dry season were $7.46{\sim}203.8\;m$ with an average of 60.49 m, while those of the wet season were $4.01{\sim}204.10\;m$ with an average of 57.66 m. Groundwater level of the dry season was higher than that of the wet season, which was caused by heavy rains between June and October, 1998 at the Jeju Island. Correlation coefficients between altitude and groundwater level for dry and wet seasons were above 0.86, and those between dry season and wet season groundwater levels were very high above 0.95. 257 groundwater level data were classified at an interval of 500 m. Average values for altitude, groundwater levels and distance from shoreline were calculated for 17 intervals. Altitude and groundwater level fur dry and wet seasons at $0{\sim}4\;km$ intervals were increased with distance from shoreline, but those at $4{\sim}9\;km$ intervals were irregularity. Linear functions of the groundwater level for dry and wet seasons as distance from shoreline were estimated, and the coefficient of determinant at $0{\sim}4\;km$ interval data was higher than it at $0{\sim}9\;km$ interval data. Increasing rate of groundwater level at $0{\sim}4\;km$ intervals was more 2 times than it at $0{\sim}9\;km$ intervals. This results are caused by linear increase of groundwater level to 4 km from shoreline and by irregularity of groundwater level at the $4{\sim}9\;km$ intervals.