• Journal of Sericultural and Entomological Science
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• v.7
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• pp.1-26
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• 1967

In order to develop the standards for the measurement of drought resistance in mulberry trees (Morus genus) the varietal differences of drought resistance were measured for 30 mulberry varieties, and the relationships between the drought resistance and the histological and physiological characteristics of mulberry leaves were investigated. The results were summarized as follows; 1. It is reasonable to use the drought resistance ratio, expressed by D/D'＊100, for the standard of drought resistance measurement for mulberry tree as a perennial tree crop. Where: D stands for growth amount(shoot length) in the plot of dry treatment, at the end of treatment. D' stands for an expected value of D which is expressed by B＊C/A. Here, A is the growth amount of wet treatment plot at the beginning of treatment, B is the growth amount of dry treatment plot at the beginning of treatment, and C is the growth amount of wet treatment plot at the end of treatment. 2. The results obtained from the application of above formula showed that the varieties Cadaneo, Tahozosaeng, Yongchunchuwu, Kaeryang suban. and Kabsun were highly resistant to drought and the varieties Jukmok, Shipyung, Sobun, Kaeryangzosaeng shipmoonza and Chungagokyo were highly susceptible. 3. Among leaf tissues. the rate of inter-cellular space showed the highest relationship with drought resistance. The correlation coefficient calculated (r=0.4153) was highly significant. Other leaf tissues such as epidermis and palisade showed no significant correlations with drought resistance. 4. The size and density of stomata were correlated to drought resistance. That is: Correlation between drought resistance and size of stomata(length ${\times}$ width)......r= -0. 3253(signif. at 5%) density(No. of stomata/l$\textrm{mm}^2$......r= +0.5047(signif. at 1%)

• Tunnel and Underground Space
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• v.13 no.2
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• pp.100-107
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• 2003

Deformation is found by an external force in the rock which has internal stress. So, deformation is increased in time what is stressed under constant load. Rock materials collapse suddenly in a long period when the creep rate increases slightly. So mechanical deformability of the ground is an essential condition for determination of long term safety in structures. The result of analysis in 40%, 50%, 60%, 70% of constant load in creep test, strain velocity constants $\alpha$ and ${\gamma}$ increase with load increasement. Griggs equation is more exact than Li and Xia, Singh equation, and G$_2$of a flow constant by Burger's model decreases with stress increasement, but η$_1$,η$_2$and G$_1$ manifest irregularly in this study.

• Analytical Science and Technology
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• v.17 no.5
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• pp.423-433
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• 2004

This study was examined occurrence of bisphenol A (BPA) and nonylphenol (NP) in waterworks system of Seoul, Korea from September 2002 to December 2003. The levels of BPA and NP in Han-river and its tributaries were as followed: Paldang-dam, ND(not detected)${\sim}0.033{\mu}g/L$ and $ND{\sim}0.823{\mu}g/L$; Kyungahn-creek, $ND{\sim}0.659{\mu}g/L$ and $ND{\sim}3.827{\mu}g/L$; Whangsuk-creek, $ND{\sim}0.528{\mu}g/L$ and $ND{\sim}12.724{\mu}g/L$, respectively. In water of 6 intake-station, the contents of NP and BPA were detected $0.122{\sim}2.724{\mu}g/L$, and $ND{\sim}0.260{\mu}g/L$, respectively. In the finished- and tap-water of three drinking water treatment plants (DWTPs) around Whangsuk-creek, BPA was not detected in all samples, while NP was in ppt levels in whole. Through the process of DWTP, also, the removal ratio of NP was above 80% in all this. Therefore, this result was suggested that levels of BPA and NP in waterworks system depended on non-point contaminants and swage treatment plants in the Han-river shed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.234-245
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• 2020

This study examined the developmental trajectories of parenting efficacy of mothers of multicultural families and how these trajectories differentiate perceived mothers' career-related behaviors as well as the socio-psychological and academic characteristic of their children in the first grade of high school. The latent class analysis (LCA) and BCH method were applied by using data drawn from the 4th to 10th graders in 2011-2017 from the Multicultural Adolescents Panel Study (MAPS). Results showed that the latent profiles were classified into four groups based on the developmental trajectories of parenting efficacy of mothers of multicultural family: 'high level increasing-decreasing', 'above average increasing-decreasing', 'average unchanged', and 'below average unchanged'. As for demonstrated outcomes, the high parenting efficacy group increased when children were in elementary school but decreased when children were in middle school. At the same time, the low parenting efficacy group did not show much change during these periods. Next, parenting efficacy was a significant determinant of perceived mothers' career-related behaviors and socio-psychological and academic characteristic of their children who attend high school. Based on these results, this study implies a theoretical foundation for developing policies to encourage parenting efficacy of mothers of multicultural families and may result in positive socio-psychological and academic characteristics of their children in high school.

• Proceedings of the KIEE Conference
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• summer
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• pp.372-374
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• 2004

22.9kV 가공배전선은 여러 요소들로 구성되기 때문에 뇌격에 대한 반응도 단순하지 않다. 현재의 절연협조는 대표적인 선로모델에 패한 선로상수, 접지저항 등의 대표 값을 사용하여 EMTP로 계산한 뇌충격과전압 값을 근거로 하고 있다. 절연협조 수준에 따라 경제성이 결정되고 계산에 의한 모델해석결과는 실제의 현상과 많은 차이를 나타낼 수 있음에도 불구하고 현재의 기준은 계산과정에서 사용되는 모델과 특성 값의 유효성을 확인하는 수준에 머물고 있다. 이 연구에서는 ICG로 충격전류를 인가하여 여러 가지 경우에 애자 양단에 인가되는 과전압을 실측하였다. 실측 결과 접지특성은 애자에 인가되는 과전압에 많은 영향을 미치지 않는다는 것을 알 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.109-109
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• 2021

우리나라의 수자원 정책은 1960~80년대까지 성장 중심으로 추진되어 왔으나 환경오염, 소득 양극화 등의 여러 한계(the Limit to Growth)에 부딪히면서 성장과 함께 환경과 복지를 고려한 정책이 대두되기 시작하였다. 물분야는 수량과 수질 인프라에 지속적 투자를 통해 상수도 보급률은 97%, 하수도 보급률은 94%까지 향상되었으나, 물 서비스에 대한 계층·지역·세대 간 격차와 불평 등은 여전히 존재하고 있다. 따라서 증거기반에 입각한 전국민의 보편적 물복지 정책 실현을 위해서는 정량적 평가에 의한 물복지 수준 진단이 필요하다. 본 연구는 우리나라의 물복지 수준진단을 위한 지표와 지수체계의 개발 및 분석을 통하여 지자체의 물복지 상황을 진단하고, 이에 따른 물복지 정책을 진단하고자 한다.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.227-238
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• 2003

Understanding of a creep behavior in rocks under a constant load, due to visco-elastic properties of rock, is an essential element to predict a long term ground deformation. In order to clarify the creep characteristics of the mudstone in Duho formation at Pohang basin, deposited during Tertiary, a series of laboratory tests including physical properties, unconfined compressive strength and uniaxial creep tests, was performed. The mudstone showed a higher creep potential due to 26% of clay minerals such as illite and chlorite. The unconfined compressive strength of the rock was $462{\;}kg/\textrm{cm}^2$ in average, and four creep tests were performed under constant stress of 40 to 70 % of the strength. The creep constants in the empirical and theoretical equations were deduced from the time-strain curves obtained from the tests. Among the several equations, the empirical equation proposed by Griggs and theoretical equation of Burger’s model are appreciated as the best one to express the creep behavior of the mudstone. Instantaneous elastic strain was linearly increased with stress level but strain velocity during the first creep is decreased with a similar pattern by time lapse regardless the stress level.

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.39-51
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• 2012

The time-dependent characteristics of mudstone in this study were analyzed by performing creep tests for the mudstone in Pohang. The creep tests were conducted on various boundary conditions to observe the time-dependent behavior of mudstone and the results were compared with values predicted by established visco-elastic model and empirical equations. As a result of analysis for empirical equations proposed by Griggs(1936), Cottrell(1952) and Singh(1975), the creep constants generally tend to increase as increasing the stress level and water content. Moreover, the values predicted by Singh's equation were well fitted for the test results. Therefore, it is expected to be reasonable that creep behavior of mudstone is analyzed using Singh's equation. As a result of analysis for a Burger's model, the predicted values were well fitted for the test results. Therefore, it is expected be reasonable that the creep behavior of mudstone by a rheological model is analyzed using Burger's model.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.32-40
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• 2018

An impact localization for a carbon fiber reinforced plastic (CFRP) composite plate was performed using the multiplexed fiber bragg grating (FBG) sensors and the error-outlier based impact localization algorithm. We found that the optimal impact localization with the maximum error of 31.82 mm and the averaged error of 6.31 mm are obtained when the error threshold (ET) and constant level (CL) are 0.3 nm and 110, respectively. Moreover, the detailed process of impact localization under certain optimal parameters and the relevant results were thoroughly investigated. We conclude that the multiplexed FBG sensors and the error-outlier based impact localization algorithm are suitable for an impact localization on composite structures, and expect that they can be utilized for various structural health monitoring (SHM) in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.375-384
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• 2020

This study examined the trajectories of the marital satisfaction of parents to classify its latent classes and how marital satisfaction influences the behavioral problems of their children between the identified latent classes. The 1st to 8th and 10th data from the Korea Child-Adolescent Panel Survey were analyzed using the latent class growth analysis and BCH method. First, based on the mother's trajectory of marital satisfaction, five latent classes were identified: 'low constant', 'intermediate constant', 'temporary increment-constantly decrement', 'high constant, and 'highest constant'. At the same time, based on the father's trajectory of marital satisfaction, four latent classes were identified: 'increment', 'intermediate-slightly decrement', 'high-slightly decrement', and 'highest constant'. Second, mothers with low marital satisfaction had more children with behavioral problems, and their influence had more problems with internalized behavioral problems. These problems progressed to externalized behavioral problems as they grew. Both internalized and externalized behavioral problems were also found between the identified latent classes of the father's marital satisfaction. Children of fathers with low marital satisfaction showed more behavioral problems. These findings suggest that the marital satisfaction of parents is an important variable that can influence the behavioral problems of their children.