• Experimental and Molecular Medicine
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• v.50 no.12
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• pp.12.1-12.14
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• 2018

Osteoporosis develops with high prevalence in both postmenopausal women and hypogonadal men. Osteoporosis results in significant morbidity, but no cure has been established. Mesenchymal stem cells (MSCs) critically contribute to bone homeostasis and possess potent immunomodulatory/anti-inflammatory capability. Here, we investigated the therapeutic efficacy of using an infusion of MSCs to treat sex hormone-deficient bone loss and its underlying mechanisms. In particular, we compared the impacts of MSC cytotherapy in the two genders with the aim of examining potential gender differences. Using the gonadectomy (GNX) model, we confirmed that the osteoporotic phenotypes were substantially consistent between female and male mice. Importantly, systemic MSC transplantation (MSCT) not only rescued trabecular bone loss in GNX mice but also restored cortical bone mass and bone quality. Unexpectedly, no differences were detected between the genders. Furthermore, MSCT demonstrated an equal efficiency in rectifying the bone remodeling balance in both genders of GNX animals, as proven by the comparable recovery of bone formation and parallel normalization of bone resorption. Mechanistically, using green fluorescent protein (GFP)-based cell-tracing, we demonstrated rapid engraftment but poor inhabitation of donor MSCs in the GNX recipient bone marrow of each gender. Alternatively, MSCT uniformly reduced the $CD3^+T$-cell population and suppressed the serum levels of inflammatory cytokines in reversing female and male GNX osteoporosis, which was attributed to the ability of the MSC to induce T-cell apoptosis. Immunosuppression in the microenvironment eventually led to functional recovery of endogenous MSCs, which resulted in restored osteogenesis and normalized behavior to modulate osteoclastogenesis. Collectively, these data revealed recipient sexually monomorphic responses to MSC therapy in gonadal steroid deficiency-induced osteoporosis via immunosuppression/anti-inflammation and resident stem cell recovery.

• Korean Journal of Remote Sensing
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• v.20 no.5
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• pp.289-305
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• 2004

Atmospheric correction of Landsat Visible and Near Infrared imagery (VIS/NIR) over aquatic environment is more demanding than over land because the signal from the water column is small and it carries immense information about biogeochemical variables in the ocean. This paper introduces two methods, a modified dark-pixel substraction technique (path--extraction) and our spectral shape matching method (SSMM), for the correction of the atmospheric effects in the Landsat VIS/NIR imagery in relation to the retrieval of meaningful information about the ocean color, especially from Case-2 waters (Morel and Prieur, 1977) around Korean peninsula. The results of these methods are compared with the classical atmospheric correction approaches based on the 6S radiative transfer model and standard SeaWiFS atmospheric algorithm. The atmospheric correction scheme using 6S radiative transfer code assumes a standard atmosphere with constant aerosol loading and a uniform, Lambertian surface, while the path-extraction assumes that the total radiance (L/sub TOA/) of a pixel of the black ocean (referred by Antoine and Morel, 1999) in a given image is considered as the path signal, which remains constant over, at least, the sub scene of Landsat VIS/NIR imagery. The assumption of SSMM is nearly similar, but it extracts the path signal from the L/sub TOA/ by matching-up the in-situ data of water-leaving radiance, for typical clear and turbid waters, and extrapolate it to be the spatially homogeneous contribution of the scattered signal after complex interaction of light with atmospheric aerosols and Raleigh particles, and direct reflection of light on the sea surface. The overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected Landsat VIS/NIR imagery by SSMM appears to have good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero water-leaving radiance for the black ocean pixels. Because of the standard atmosphere with constant aerosols and models adopted in 6S radiative transfer code, a large error is possible between the retrieved and in-situ spectra. The efficiency of spectral shape matching has also been explored, using SeaWiFS imagery for turbid waters and compared with that of the standard SeaWiFS atmospheric correction algorithm, which falls in highly turbid waters, due to the assumption that values of water-leaving radiance in the two NIR bands are negligible to enable retrieval of aerosol reflectance in the correction of ocean color imagery. Validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of the classical algorithms, but is feasible with SSMM.

• Journal of the Korean Society of Child Welfare
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• no.36
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• pp.101-132
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• 2011

Using data collected from Korean mothers (N＝429) with preschool children (aged 3 to 5 years) in 12 day care centers in Seoul, this study aims to empirically demonstrate the different pathways acute and chronic stress affect parenting efficacy of mothers according to the income group to which they belong. Analytic results show mothers in the low-income group show higher levels of depressive symptoms than mothers in the middle-income group, and the former also show more frequent and higher levels of acute and chronic stress than the latter. The mediation model results show that acute stress and chronic stress did not directly affect parenting efficacy, but rather indirectly affect parenting efficacy through maternal depressive symptoms. Acute stress and chronic stress are both significant factors affecting depressive symptoms with chronic stress exerting greater influence. When the total effect was analyzed, chronic stress has a greater effect on parenting efficacy than acute stress. The effect of chronic stress on maternal depressive symptoms is greater on low-income mothers than middle-income mothers, while the effect of acute stress on maternal depressive symptoms and the effect of those symptoms on parenting efficacy are greater on middle class families than low-income families. In order to maximize effective parenting in high-risk situations, the psychological welfare of mothers needs to be protected from the environmental difficulties they face. Based on the results, policies to support women and parents at the national and social levels are discussed.

• Korean Journal of Social Welfare Studies
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• v.40 no.3
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• pp.377-406
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• 2009

This study used laten class growth analysis to identify discrete developmental patterns of delinquent behaviors in adolescence. This present article also examined associations among these trajectories to determine how the development of delinquent behaviors relates to protective and risk factors, which include parental monitoring, attachment with parent, association with deviant peers, self-control, and negative stigma from others. Four-wave panel data from a Korea Youth Panel Study were used for the latent class growth model analysis. The sample consisted of 3,446 adolescents who were assessed at 4 measurement waves with approximately 1-year interval. Four trajectories of delinquent behaviors emerged: delinquency persistence, delinquency increaser, delinquency decreaser, normative group(almost no delinquent behaviors). Association with deviant peers had the most proximal strong influence on the probability of being in the delinquency increaser and delinquency persistence group compared, noed to the normative group. Parental monitoring, self-efficacy and negative stigma also differentiated the four delinquent behavior trajectories from one another after controllig for socio-demographic variables. The study suggested that there is a significant heterogeneity in the timing and change rate of delinquency progression. Adolescent delinquency prevention and intervention programs will need to consider this heterogeneity and enhance attention to protective and risk factors depending on the subpopulation.

• Journal of the Korean Society of Child Welfare
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• no.40
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• pp.41-71
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• 2012

The purpose of this study is to examine longitudinal impacts of various factors on happiness in primary school children. Specifically, attachment theory and ecosystems perspective were utilized for the purpose of this study. We used Korea Youth Panel Survey, which is a 5-year longitudinal data collected from fourth grade in elementary school to second grade in middle school Latent growth model was employed as the analytic method. The findings of this study are as follow: first, academic achievement, self-esteem, parent attachment, peer attachment, teacher attachment, and community attachment all decreased over the 5-year study period. Also, the intercept and the slope variance of variables were found to be statistically significant. This means that there are significant differences in the intercept and the slope of individuals. Second, self-esteem, parent attachment, and peer attachment were found to have cross-sectional influences on happiness. This means that self-esteem, parent attachment, and peer attachment are positively associated with happiness at the intercept. Also, self-esteem, parent attachment, teacher attachment, and community attachment were found to have longitudinal influences on happiness. This means that the higher levels of community attachment at the intercept is associated with slower the rate of decrease in happiness at the slope. In addition, faster rates of decrease in self-esteem, parent attachment, teacher attachment, and community attachment are associated with faster the rate of decrease in happiness. Third, this study conducted multiple group analysis with gender. The findings of this analysis revealed no significant differences in analytic models between males and females. Based on these findings, theoretical and practice implications with regard to happiness in primary school children are discussed.

• Korean Journal of Social Welfare Studies
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• v.49 no.2
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• pp.93-124
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• 2018

Using the Korean Survey of Household Finances and Living Conditions panel data from 2012~2016, this study analyzed youth (19~34 years) poverty and employment and examined the factors that affect employment status. The analysis revealed an increase in the proportion of young people who are students or jobless; the economic conditions of the young people varied by factors such as marital status, education, job status, and loans; and the government public transfer policy had little impact on reducing the relative poverty rate of the youth. We also examined the factors affecting the youth's employment status and the risk of being employed in low-paid jobs, using multi-logit and logit regression model respectively. Considering employment status, the older and more educated the youth were, the less frequently they were employed in temporary or daily jobs instead of regular ones, but there was no difference between genders in terms of having temporary or daily jobs. A logit analysis on the determinants of low-paid jobs demonstrated that women, the less educated, spouses or children of the household, and temporary or daily workers have a greater probability of working at low-paid jobs. As women became older, their risk of having low-paid jobs increased, which demonstrated the phenomenon of "lock-in" at low-paid jobs. Temporary or daily workers of all age groups faced a higher risk of lowpaid employment, which stood out for the youth. Based on these results, we suggest that government employment and welfare policies should consider individual characteristics of the youth and their life cycle, along with efforts to supply decent jobs, continuously and stably.

• Korean Journal of Social Welfare Studies
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• v.47 no.3
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• pp.251-277
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• 2016

The purpose of this study was to examine the effects of adolescents' mobile phone dependency on depression and aggression and to identify mediating effects of parenting attitudes and peer relationships. This study used data from the 4th and 5th waves of 2010 KCYPS (Korean Children and Youth Panel Survey). Structural Equation Model(SEM) was conducted to examine the mediating effects of parenting attitudes and peer relationships. The results showed that adolescents' mobile phone dependency had positive effects on depression and aggression. In addition, the relationship between adolescents' mobile phone dependency and depression was partially mediated by parenting attitudes and peer relationships. The relationship between adolescents' mobile phone dependency and aggression was also partially mediated by parenting attitudes and peer relationships. Based on these findings, further suggestions are provided to reduce adolescents' depression and aggression by decreasing mobile phone dependency and improving parenting attitudes and peer relationships.

• Journal of the Korean Society of Child Welfare
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• no.54
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• pp.145-172
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• 2016

The purpose of this study was to examine whether parenting attitudes would have an effect on the developmental trajectories of school adjustment for adolescents in out-of-home care. Additionally, we hypothesized that this model would be different between boys and girls. In this study, we analyzed three waves of data collected from 341 adolescents living in residential facilities, group homes or foster homes by using cluster sampling methods. Growth-curve longitudinal analysis was conducted, and the results indicated that levels of school adjustment had increased from the 1st through the 3rd grade of middle school. Positive parenting attitudes had a positive impact on initial school adjustment and rate of change, whereas negative parenting attitudes had a negative impact only on the initial school adjustment. Second, multi-group analysis revealed that there were group differences between boys and girls in their initial school adjustment by positive parenting attitudes. Based on these results, this study discussed further suggestions to increase school adjustments for adolescents in out-of-home care.

• Journal of the Korean Society of Child Welfare
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• no.40
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• pp.109-137
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• 2012

The purpose of this study is to examine the effects of direct experience with school violence on internet game addiction and school adjustment focusing on the mediating effect of depression. A survey of 559 middle school students in Seoul, Gyeonggi Province, and Pusan was conducted. The data were analyzed using AMOS 18.0. The results are as follows. First, 43.9% of the study sample experienced school violence in the previous year. In terms of internet game addiction, 45.9% were identified to be potentially addicted, and 6.6% were considered to be addicted to internet games. Second, results from the structural equation model show that school violence has positive effects on depression and internet game addiction. Third, depression has a positive effect on internet game addiction and a negative effect on school adjustment. Fourth, internet game addiction negatively affects school adjustment. Based on these research results, the findings from this study suggest need for intervention programs targeted to prevent school violence, internet game addiction, depression, and school adjustment.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.5
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• pp.141-157
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• 2019

The purpose of this study was to verify the effects of personal characteristics and military service experience on their entrepreneurial intention. Hypotheses were developed based on extant literature and tested using the data collected by surveys to retiring officers and NCOs. The conclusions drawn from the analysis were as follows. First, the major factors affecting the voluntary self-employment intention are role model, perceived desirability, and working environment. Second, the biggest difficulty in preparing to start a self-employed business is the lack of founding capital and entrepreneurial information. Third, the respondents believe that military career is not helpful in starting a business. Fourth, there were many negative perceptions that the education and training from the military does not help the self-employment. As a result, it is believed that improvement of entrepreneurial education in the military and expansion of entrepreneurial education during service are required. Especially, the education focusing on self-employed entrepreneurship should be improved. It is recommendable that the entrepreneurial education now being carried out by the Military Outplacement Training Institute should be extended not only during the outplacement period but also the normal service period, thereby increasing the intention of the military official.