• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.611-620
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• 2006

In the shear failure mechanism of a beam, beam and arch actions always exist simultaneously. According to the shear span to depth ratio, the proportion between these two actions is varied and the contribution of these actions to shear capacity is changed. Moreover, the current codes provide recommendations based on experimental results of normal strength concrete, so the application range of concrete strength must be extended. Based on this mechanism and new requirement, a simplified analytical equation for shear capacity prediction of reinforced high strength concrete beams without stirrups is proposed. To reflect the change in the contribution between these actions, stress variation in the longitudinal reinforcement along the span is considered by use of the Jenq and Shah Model. Dowel action with horizontal splitting failure and shear friction between cracks are also taken into account. ize effect is included to derive a more precise equation. Regression analysis is performed to determine each variable and simplify the equation. And, the formula derived from theoretical approaches is evaluated by comparison with numerous experimental data, which are in broad range of concrete strength(especially in high strength concrete), shear span to depth ratio, geometrical size and longitudinal steel ratio. It is shown that the proposed equation is more accurate and simpler than other empirical equations, so a wide range of a/d can be considered in one equation.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.412-419
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• 2009

The purpose of this study was to provide the reference data evaluating the treatment effect of orthopedic appliances. The skeletal and dental growth increments were measured in 24 normal mixed dentition children (boys: 14, girls: 10) by three serial lateral cephalograms: initial mean age: 9${\pm}$1.3 years, mean observation period: 13${\pm}$1.3 months. Cephalometric changes were analysed. The results were as follows: 1. In boys, the maxilla showed forward and downward growth pattern and the mandible showed forward growth pattern (p<0.05). In girls, the maxilla and mandible showed forward and downward growth pattern(p<0.05). 2. Horizontal growth of both maxilla and mandible in girls was superior to those in boys (A point; girls: 2.39mm, boys: 1.26mm, with p<0.05), whereas vertical growth of both maxilla and mandible in boys was similar to those in girls. 3. The change in tooth axis showed labioversion of upper incisor (p<0.01) and comparatively stable lower incisor position.

• Journal of Korean Society of Forest Science
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• v.88 no.2
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• pp.240-248
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• 1999

On the basis of data obtained from five forest roads collapsed due to a heavy rainfall of 1995 in Chunchon, Kangwon-do, this study was carried out to evaluate and predict the fill slope failure of forest roads with four factors of forest road structure and those of location condition by using Quantification theory(II). The results were summarized as follows ; In the structure factors of forest road, the fill slope failure was mainly occurred in longitudinal gradients less than $2^{\circ}$ or more than $4^{\circ}$, distance of surface-flow longer than 80m, fill slope length greater than 6m, and fill slope gradients steeper than $35^{\circ}$. In the factors of location condition, the failure was mainly occurred in ridge portion of road position, weathered rock and soft rock of constituent material, slope gradients in the range from $35^{\circ}$ to $45^{\circ}$, and concave and convex of longitudinal slope forms. The priority order for factors influencing on fill slope failure was ranked by fill slope length, constituent material, road position, and so on. And the rate of correct discrimination by analysis of fill slope failure was estimated at the high prediction of 86.5%.

• Journal of Science Education
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• v.34 no.1
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• pp.1-11
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• 2010

This study analyzes the factors influencing academic achievement on mathematic and scientific subject and its change in Korean youth by using a sample from KYPS(Korea Youth Panel Survey) data. The results are as follows: First, academic achievement on mathematic and scientific subject of Korean youth shows quadratic curve that their interrelationship between intercept and slope of academic achievement are negative which is statistically significant. Second, analysis of Latent Growth Models shows that parents, teacher, peer group, self esteem, income of family, high school tracks are found to be a statistically significant factor on mathematic. And scientific subject is affected by parents, teacher, peer group, self esteem, income of family, high school tracks. Also, Interesting finding is that father's job is not significant to dependent variables. These findings show that academic achievement on mathematic and scientific subject of the Korean youth are the quadratic curve and influenced by parents, teacher, peer group, self esteem, income of family, high school tracks. To improve youth's mathematic and scientific, Korea educational fields and educators should have policy to care youth's relationship with parents, teachers and self esteem.

• Korean Journal of Social Welfare
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• v.66 no.1
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• pp.61-85
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• 2014

Lately, as the problem of the aged poverty becomes a big social issue, this paper studies the problem of financial stability with respect to the income and consumption of before-and-after retirement generations. After dividing the data in Korean Longitudinal Study of Ageing(KLoSA) into retired and non-retired groups, this study compares the difference among ageing groups by cross analysis and t-test. First, the result tells that the total personal income of retired group is lower than the one of non-retired group. Second, the public pension income benefit ratio of retired group is only 30% of it's total income, and the amount of public pension appears to be 40% of the total pension income. The benefit ratio of the personal pension income is low as about 1% in both groups, The private transfer income of the retired group takes relatively large portion in its total personal income. Third, as people gets older, financial stability gets worse because consumption does not decrease as much as the income decreases. Fourth, it is turned out that the expectation of old life supporting from nation is low in both groups. Fifth, the factors that affects the income of the public pension in the retired group are gender, age, education, and health status, when compared with the factors to the personal total income of the non-retired group. In terms of policy, this paper emphasizes the needs of the intensification of the public pension and the support for the revitalization of the personal pension.

• Korean Journal of Social Welfare
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• v.66 no.4
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• pp.5-23
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• 2014

This study performed a series of analyses to examine the effects of regular exercise on depression using data from the HAS (Hallym Aging Study) and the KLoSA(Korean Longitudinal Study of Ageing). The effect of regular exercise on depression was tested through propensity score matching methods. In addition, analyses of five indirect effect models were performed to verify a theoretical description about how regular exercise has an effect on depression. The results of analysis were as follows. First, it was found in the two samples that elderly people who exercise regularly have a lower level of depression compared to those who do not. Second, the results of analysis of five indirect effect models were all significant. The psycho-physiological models showed the effect of regular exercise on depression using ADL(Activities of Daily Living) and grip strength. The psycho-social models also demonstrated the effect of regular exercise on depression using variables related to social activities. Based on these findings, intervention strategies to prevent depression was discussed.

• Korea journal of population studies
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• v.26 no.2
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• pp.197-219
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• 2003

Using the panel data from the National Longitudinal Survey of Youth 79, we test the effects of relative status inconsistency within American young couples on the direction of migration as well as on migration propensities. Key findings in this study indicate that only couples in which the wife's education is greater than the husband's education are less likely to migrate than couples for which the wife's status is as lower than the husband's. There are no differences in the propensity for rural couples to migrate to urban counties or for urban couples to migrate to rural counties based on status inconsistency between spouses. However, we find that there is the gendered difference in the effect of status inconsistency on the probability of family migration. A spouse's higher status has an impact on a wife's probability of migration but does not affect a husband's migration propensity in a comparable situation. These findings are most consistent with a gender role perspective on migration since increases in the wife's status have little effect on family migration, once the presence and age of children is controlled.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.325-354
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• 2020

This study utilized longitudinal data from the 2013 year (Secondary Middle School) to 2017 year (Secondary High School) of the Seoul Education Termination Study. Using the latent growth model and the piecewise growth model, we investigated the changes in mathematics academic achievement, internal factors(self-concept, self-control, self-assessment of life satisfaction), and external factors(school climate, guardians) as students' grades increased, and examined whether internal factors and external factors influence the changes in mathematics academic achievement. We examined whether internal and external factors influence the change in academic achievement. As a result of analysis, it was found that mathematics academic achievement remained unchanged from the first grade of middle school to the second grade of middle school, and steadily increased from the second grade of middle school to the first grade of high school, and then decreased slightly in the second grade of high school. The internal and external factors had little change. It has been found that self-concept, self-control as internal factors, and school climate as external factors influence changes in mathematics academic achievement.

• Management & Information Systems Review
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• v.39 no.3
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• pp.37-51
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• 2020

Customer participation in the service encounter plays an important role in the interaction process. In addition, customer participation is affecting the development of relationships between customer-service provider. Previous researches revealed the role of customer participation through a fragmented and cross-sectional approach, however, given the dynamics of the relationship, it is necessary to identify the role of customer participation from a longitudinal perspective. In addition, it is necessary to determine the cause of the overlap between the antecedent variables and consequent variables. This study aims to identify the relational role of customer participation by clarifying how customer participation affects relationship development from a longitudinal perspective, focusing on trust and commitment variables which are keys to relationship marketing. The related role of customer participation is analyzed through a regression analysis through long-term data. The results of the study showed that commitment(t1) directly had a positive effect on customer participation. However, trust(t1) has been shown to have a direct positive effect on the sub-dimensions of customer participation, such as personal interaction and responsible behavior. Customer participation(t2) affected by this trust(t1) and commitment(t1) again turned out to have a positive effect on trust(t3) and commitment(t3). In conclusion, although customer participation is affected by the relational variables, it can be seen that customer participation is a major factor that can improve the relational variables again through the interaction process. For this reason, a service firm can seek to develop relationships with customers by drawing and utilizing their needs to exchange information and to interact in the service encounter.

• Progress in Medical Physics
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• v.26 no.2
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• pp.106-111
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• 2015

In Tomotherapy the couch sags during the treatment due to the weight of the patient. In this study, we developed a simple method to obtain the amount of the sag and the pitch angle of the couch using the image processing technique of MVCT images in Tomotherapy. Using the method we evaluated the sag and pitch of couch for 22 head and neck patients and one craniospinal irradiation (CSI) patient. The sag and the average pitch angle of couch were 0.40~1.54 mm and $0.7^{\circ}$ for head and neck patients, respectively. For head and neck patients, the sag increased as the longitudinal length of the irradiation volume increased and the pitch angle showed no relationship with the longitudinal length. For the CSI patient the sag was 4.97 mm. Using the method the amount of the couch sag could be measured easily and the measured data could be useful in determination of margins considering the table sag error.