• Journal of Korea Water Resources Association
• /
• v.46 no.11
• /
• pp.1115-1128
• /
• 2013

The purpose of this study is to evaluate the suspended solids and eutrophication processes relationships in Chungju lake using CE-QUAL-W2, two-dimensional (2D) longitudinal/vertical hydrodynamic and water quality model. For water quality modeling, the lake segmentation was configured as 7 branches system according to their shape and tributary distribution. The model was calibrated (2010) and validated (2008) using 2 years of field data of water temperature, suspended solids (SS), total nitrogen (TN), total phosphorus (TP) and algae (Chl-a). The water temperature began to increase in depth from April and the stratification occurred at about 10 m early July heavy rain. The high SS concentration of the interflow density currents entering from the watershed was well simulated especially for July 2008 heavy rainfall event. The simulated concentration range of TN and TP was acceptable, but the errors might occur form the poor reflection for sedimentation velocity of nitrogen component and adsorption-sediment of phosphorus in model. The concentration of Chl-a was simulated well with the algal growth patterns in summer of 2010 and 2008, but the error of under estimation may come from the use of width-averaged velocity and concentration, not considering the actual to one side inclination by wind effect.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.5
• /
• pp.741-749
• /
• 2018

The purpose of this study is to propose a rational and scientific damage calculation model in relation to damages caused by bid rigging in construction projects. Previous studies and precedents in relation to calculating damages from bid rigging suggest that the main issue was the lack of consideration in standards for deciding successful bids, selection of inadequate standard comparative markets, insufficiency in analyzing the appropriateness of competitive bid price influence factors, and absence of calculation model verification. In order to improve on these issues, a damage calculation method on alternative tenders for construction projects was proposed. For this calculation model, first, a standard market adequate to the successful bid selection standards was determined, second, an appropriate factor was selected by analyzing the correlation between competitive bid price influence factors, and third, a regression analysis was conducted on the selected factor. Lastly, this was demonstrated through verification of appropriateness, significance & normality of the proposed model and application of actual bid rigging cases. Through the proposed calculation model, this study seeks to serve as a base to prevent opportunity damages for parties involved in related court cases by early resolution of disputes and relief from issues of unfair damage burdens on a particular party.

• Journal of the Korean earth science society
• /
• v.25 no.5
• /
• pp.303-314
• /
• 2004

The purpose of this study is to analyze high school students' understanding levels about earth science terms written in Chinese characters according to learners' characteristics. In order to investigate how the responses vary according to their characteristics, first of all, proper scientific terms are selected, and then corre sponding questions about them are offered as subjects, which consists of a Korean characters type, a picture type, and a Korean and Chinese characters type. During paper test and interview, the questions are given to fifteen students from general high schools in Jecheon, Chungbuk Province. The results of the study are as follows; Students in formal operation level and field-independency answered very well and also the terms of Chinese characters type and picture type improve the students' understanding and memorization. Generally, Chinese characters have more positive influence on their learning than the negative. Therefore, in general, it seems that it's more effective to explain the sound and meaning of terms in detail and to give learners enough time to draw a picture about each term by themselves when scientific terms are delivered to students in Chinese characters in class.

• The Korean Journal of Financial Management
• /
• v.26 no.3
• /
• pp.139-169
• /
• 2009

This paper introduces the modified VaR which takes into account the asymmetry and fat-tails of financial asset distribution, and then compares its out-of-sample forecast performance with traditional VaR model such as historical simulation model and Riskmetrics. The empirical tests using stock indices of 6 countries showed that the modified VaR has the best forecast accuracy. At the test of independence, Riskmetrics and GARCH model showed best performances, but the independence was not rejected for the modified VaR. The Monte Carlo simulation using skew t distribution again proved the best forecast performance of the modified VaR. One of many advantages of the modified VaR is that it is appropriate for measuring VaR of the portfolio, because it can reflect not only the linear relationship but also the nonlinear relationship between individual assets of the portfolio through coskewness and cokurtosis. The empirical analysis about decomposing VaR of the portfolio of 6 stock indices confirmed that the component VaR is very useful for the re-allocation of component assets to achieve higher Sharpe ratio and the active risk management.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.4
• /
• pp.1013-1025
• /
• 2016

The purpose of this study was to analyze longitudinal effect of physical education activity (PEA) score on self-rated health evaluation change (SHEC). This study used hierarchical linear and nonlinear models to investigate of the SHEC during the transition into adolescence (from middle school 1st to high school 2nd grade). Using the Korea children and youth panel survey (KCYPA), data were collected over the course of five years (from 2010 and 2014). HLM 6.8 computer program was used to analyze the data. The result were as follows. First, boys' SHEC increased across the five years, and girls' SHEC decreased across the five years. Second, boys' the self-rated health was increased across the three years and decreased across the two years. Third, girls' the self-rated health was increased across the two years and decreased across the three years. Fourth, the PEA score of 1st grade of high school showed a significant positive association with the boys' SHEC. Fifth, the PEA score of 1st grade of middle school showed a significant negative association with the girls' SHEC.

• Journal of the Economic Geographical Society of Korea
• /
• v.17 no.3
• /
• pp.538-553
• /
• 2014

The aim of this study is to consider the degree of supply-demand balance in relation to the characteristics of retail sale activities in depopulation aging regions and the degree of aging by using simple regression analysis. The major findings of this study are as follows. While aging society, and aged society regions show a similar major retail sale industries, super-aged society shows fewer major industries and different industry composition. These characteristics are seen by different phenomenon and the background of the particular retail structure. The first one is that the number of employees per establishment increases when the aging phenomenon is not accelerated, and the annual sales per capita purchasing power decrease because their purchasing power becomes lower when the aging phenomenon is severe, but it also shows a high density of establishments because disperse location of establishment within depopulation aging region. The second one is the retail structure with high labor productivity in a aged and superaged society region. We identify the extent of demand and supply in general retails, fuel retails, food and beverage, and tobacco retails which represent the highest sales rates in depopulation aging region. As a result, general retails are seen as 'supply-demand balance region' in aged and super-aged society, fuel retail sales in aged and super-aged society which generally shows less sales, and food and beverages, and tobacco retails in super-aged society. The higher the degree of aging is, the less the regional differences in the gap between demand and supply is. This is because the difference in purchasing power between these regions is small.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.3
• /
• pp.467-473
• /
• 2010

The objectives of this study were to determine various bio-active components from some brown rice and milled rice of some cultivars, as well as to assess their contribution to the radical scavenging linked-antioxidant activity. DPPH or ABTS radical scavenging activities, and reducing power have been used to investigate the relative antioxidant activities of 70% ethanol extracts. The contents of total polyphenol, total flavonoid, $\gamma$-oryzanol, and vitamin E in the extracts were also measured by spectrophotometric methods or HPLC. The antioxidant components and antioxidant activities of 70% ethanol extracts from brown rice were higher than those from milled rice. In addition, our results showed that the high level of antioxidant compounds was found in brown rice of Hongjinju, and the antioxidant activities of the 70% ethanol extracts from pigmented brown rices, such as Hongjinju and Heugkwang, were comparably higher than the others.

• Journal of Korean Society of Forest Science
• /
• v.102 no.2
• /
• pp.198-203
• /
• 2013

Herein we analyzed the nuclear DNA content and the histological characteristics of the triploid of the 'Hyunsasi' (Populus alba ${\times}$ P. glandulosa $F_1$) which were developed for biomass production and molecular breeding research. The flow cytometric analysis showed that the nuclear DNA content of the 3 triploids were 1.6 times greater than those of the diploid. In terms of histological characteristics, the cross-section area of the stem of 'Line-18' was 1.6 times larger than that of the diploid. The area of pith, and cortex and phloem of the stem of 'Line-18' was also 1.6 and 2.0 times larger than that of the diploid, respectively. Moreover, the length and area of guard cell of 'Line-18' was 1.2 times larger than that of the diploid. These results helps to understand the cytological characteristics of the triploid poplar clones, and further investigations in the growth rate and wood properties of the triploids growing in the field will determine whether the triploid poplars are good candidates for molecular breeding programs and for the improvement of industrial biomass productivity.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.8
• /
• pp.1257-1263
• /
• 2014

Different fat extraction methods such as the Rose-Gottlieb, Folch, and hydrolytic methods were compared in terms of their fatty acid contents of milk powder. Contents of total saturated fatty acids by the Rose-Gottlieb, Folch, and hydrolytic methods were 8.578, 8.302, and 8.711 g/100 g milk powder while contents of total unsaturated fatty acids by the Rose-Gottlieb, Folch, and hydrolytic methods were 11.513, 11.143, and 11.669 g/100 g milk powder, respectively. These results suggest that the hydrolytic method has a similar fatty acid composition as the well-known Rose-Gottlieb method. In uncooked chicken, total fatty acid contents of breast, gamb, and wing were 6.302, 8.313, and 11.346 g/100 g, respectively. Among different cooking methods, frying increased content of total trans fatty acids up to 0.034 (breast), 0.112 (gamb), and 0.123 g/100 g (wing).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.10
• /
• pp.1258-1264
• /
• 2017

The effects of two cooking methods (grilling and boiling) on fat content, fatty acid composition, vitamin A, and vitamin E levels of chicken (breast, wing, thigh, and leg) were investigated. Cooking loss was in the range of 19.09~41.17%, and grilled chicken showed higher cooking loss than boiled chicken in all parts except the thigh. All treatments enhanced fat content except boiled chicken breast. Fatty acid contents of chicken significantly increased or decreased after heat treatments (P<0.05). Grilled wing showed the highest levels of saturated (SFA) and unsaturated fatty acids (UFA), and the highest UFA/SFA ratio was detected in boiled thigh. The highest content of trans fatty acids was detected in boiled wing (137.67 mg/100 g), although no significant difference with grilled wing (P>0.05), and trans fatty acids in breast was not detected. The content of vitamin A tended to decrease with heating in all chicken parts, whereas the content of vitamin E varied depending on the part and cooking method. In other words, vitamin E content of wing decreased after cooking, whereas contents of thigh and leg significantly increased after cooking (P<0.05). These results are helpful for choosing the best cooking method according to the part of the chicken for proper consumption of fats and vitamins.