• The Journal of Korean Society for School & Community Health Education
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• 제20권1호
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• pp.69-84
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• 2019

Objectives: The purpose of this study is to examine change in adolescent depression across time and to determine the relation between individual and neighborhood socioeconomic status (SES) and depression. Methods: This study employed multilevel latent growth analysis using longitudinal data from Korea Children and Youth Panel Survey. A sample of this study consists of 2,351 adolescents who were in first grade of middle school in 2010. Results: Results showed that both initial level and downward trajectory of depression varied significantly across individuals as well as across neighborhoods. On the individual level, self-rated economic condition(b=-0.203, p<.001) was related to the initial level of depression. Adolescents whose father had a high educational level(b=0.028, p<.001) or whose mother had a low educational level(b=-0.022, p=.011) had lower rates of decline in adolescent depression. On the neighborhood level, neighborhood deprivation index (b=0.003, p=.019) and gini coefficient(b=0.124, p=.040) were associated with lower rates of decline in depression. Conclusions: Low SES in adolescence is correlated with worse mental health, especially depression. Social disparities in depression likely originate before adulthood. The findings argue for the importance of understanding depression in adolescence from a multilevel or ecological framework.

• Journal of Korean Academy of Nursing
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• 제45권6호
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• pp.857-867
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• 2015

Purpose: The purpose of this study was to investigate individual and organizational level of cardiovascular disease (CVD) risk factors associated with CVD risk in Korean blue-collar workers working in small sized companies. Methods: Self-report questionnaires and blood sampling for lipid and glucose were collected from 492 workers in 31 small sized companies in Korea. Multilevel modeling was conducted to estimate effects of related factors at the individual and organizational level. Results: Multilevel regression analysis showed that workers in the workplace having a cafeteria had 1.81 times higher CVD risk after adjusting for factors at the individual level (p =.022). The explanatory power of variables related to organizational level variances in CVD risk was 17.1%. Conclusion: The results of this study indicate that differences in the CVD risk were related to organizational factors. It is necessary to consider not only individual factors but also organizational factors when planning a CVD risk reduction program. The factors caused by having cafeteria in the workplace can be reduced by improvement in the CVD-related risk environment, therefore an organizational-level intervention approach should be available to reduce CVD risk of workers in small sized companies in Korea.

• Survey Research
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• 제18권2호
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• pp.67-98
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• 2017

The purposes of this study are to identify the latent classes of school violence depending on bullying and victimized experience by type and the influences of individual-level and school-level variables on determining these latent profiles. For these research goals, the present study utilized data from the Seoul Education Longitudinal Study(SELS) 5th wave, containing data from 2,195 middle school students who experienced school violences more than once. Multilevel latent profile models were applied to examine school violence among students. Our results indicated that there were four latent classes; high-level bullying and victimized group (1.7%), mainly bullying group(2.1%), mainly victimized group(3.7%), verbal bullying and victimized group(92.5%). Gender, resilience, self-control, peer relationship, parental relationship were significant determinants of the latent profiles at student level. Teacher-student relationships, school violence prevention, gender ratio of school were significant determinants of the latent profiles at school level. The present study contributed to extending theoretical discussions by classifying students into groups based on frequency and different forms of bullying and victimization. Moreover, this study examined determinants of student and school level simultaneously by dealing with multilevel data.

• Journal of Korean Academy of Nursing
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• 제38권2호
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• pp.287-297
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• 2008

Purpose: The purpose of this study was to identify factors related to nurses' organizational citizenship behavior using multilevel analysis which included both nurse characteristics at individual levels and nursing unit characteristics at group levels. Methods: The sample was composed of 1,996 nurses who were selected from 182 nursing units in 28 hospitals in six metropolitan cities and seven provinces using cluster sampling. Data were collected using self-reported questionnaires from February to March 2006. Results: The results of the study indicated that individual level variables related to organizational citizenship behavior were religion, job position, clinical career, self efficacy, positive affectivity, and supervisor support. The group level variables related to organizational citizenship behavior were collective efficacy, number of nurses in a nursing unit, and the average salary level of a nursing unit. 30.9% of individual level variances of organizational citizenship behavior were explained by the nurses' individual level variables. The explanatory power of group level variables, which is related to group level variances of organizational citizenship behavior, was 75.5%. Conclusion: This research showed that it was necessary to develop appropriate strategies related to not only individual factors, but also higher-level organizational factors such as collective efficacy, to improve individual performances in the hospital.

• Journal of Preventive Medicine and Public Health
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• 제55권5호
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• pp.444-454
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• 2022

Objectives: We aimed to identify the factors related to depression and quality of life in patients with hypertension by using multilevel regression analysis. Methods: In 2019, 229 043 participants in the Korean Community Health Survey were selected as the study group. Individual factors were identified using data from the 2019 Community Health Survey. Regional factors were identified using data from the National Statistical Office of Korea. Multilevel regression analysis was conducted to find individual and local factors affecting depression and quality of life in patients with hypertension and to determine any associated interactions. Results: As individual factors in patients with hypertension, women, those with lower education-levels, recipients of basic livelihood benefits, and those with poor dietary conditions showed stronger associations with depression and quality of life. As regional factors and individual-level variables in patients with hypertension, lower gross regional personal income, fewer doctors at medical institutions, and lower rates of participation in volunteer activities presented stronger associations with depression and quality of life. In addition, the associations of depression with gross regional personal income, the number of doctors at medical institutions, and dietary conditions were significantly stronger in patients with hypertension than in patients without hypertension. The associations of gender and employment status with quality of life were also significantly greater. Conclusions: Policy interventions are needed to adjust health behaviors, prevent depression, and improve quality of life for patients with hypertension, especially for those with the risk factors identified in this study.

• Journal of the korean academy of Pediatric Dentistry
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• 제51권1호
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• pp.40-54
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• 2024

This study aims to identify the regional distribution in the prevalence of dental caries and related multidimensional factors among 12-year-old children in Korea. Data from the 2018 Child Oral Health Survey were used to calculate the average DMFT index of 12-year-old children in metropolitan cities, and a multi-level regression model was applied to explain the regional distribution of dental caries prevalence and related factors. Factors were divided into two levels by administrative structure. This study finds a significant regional difference in the prevalence of dental caries in 12-year-old Korean children across metropolitan cities. Multilevel analysis showed that district-level factors (average number of pit and fissure-sealed permanent teeth, dental treatment demand rate, preventive treatment rate, sex ratio, and number of dentists per 100,000 people) and metropolitan-level factors (intakes of cariogenic beverages and number of pediatric dental hospitals and clinics per 100,000 people) had a significant effect on dental caries prevalence (p < 0.05). Individual characteristics and local socio-environmental factors influence the prevalence of dental caries. Especially considering the strong dependence on preventive treatment and accessibility to dental care services, it is necessary to provide adequate preventive treatment and expand health care resources in high-risk areas of dental caries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제35권1호
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• pp.44-49
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• 2022

In this paper, we investigated current (I)- and voltage (V)-sweeping properties in a double-stack structure, Ge₂Sb₂Te₅/Ti/W-doped Ge₈Sb₂Te₁₁, a candidate medium for applications to multilevel phase-change memory. 200-nm-thick and W-doped Ge₂Sb₂Te₅ and W-doped Ge₈Sb₂Te₁₁ films were deposited on p-type Si(100) substrate using magnetron sputtering system, and the sheet resistance was measured using 4 point-probe method. The sheet resistance of amorphous-phase W-doped Ge₈Sb₂Te₁₁ film was about 1 order larger than that of Ge₂Sb₂Te₅ film. The I- and V-sweeping properties were measured using sourcemeter, pulse generator, and digital multimeter. The speed of amorphous-to-multilevel crystallization was evaluated from a graph of resistance vs. pulse duration (t) at a fixed applied voltage (12 V). All the double-stack cells exhibited a two-step phase change process with the multilevel memory states of high-middle-low resistance (HR-MR-LR). In particular, the stable MR state is required to guarantee the reliability of the multilevel phase-change memory. For the Ge₂Sb₂Te₅ (150 nm)/Ti (20 nm)/W-Ge₈Sb₂Te₁₁ (50 nm), the phase transformations of HR→MR and MR→LR were observed at t<30ns and t<65ns, respectively. We believe that a high speed and stable multilevel phase-change memory can be optimized by the double-stack structure of proper Ge-Sb-Te films separated by a barrier metal (Ti).

• Journal of Veterinary Clinics
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• 제34권2호
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• pp.140-145
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• 2017

The goal of this study was to investigate risk factors associated with porcine reproductive and respiratory syndrome (PRRS) in pig farms in the Republic of Korea using logistic regression and a multilevel model. A cross-sectional study was applied to 305 pig farms with a questionnaire-based interview by veterinarians between March 2014 and February 2015. The questionnaire comprised eight categories: proximity to neighbors, disinfection, visitors, vehicles, insecticides, wild animals, gilts, and feeding. In total, 61 questions in eight categories related to pig farm biosecurity were investigated. Farms were classified as PRRS stable or unstable based on the results of an antibody test and PCR. For univariate analysis, keeping production records with computers (OR = 0.283, 95% CI = 0.056 - 1.425), accredited farm with no use of antibiotics (OR = 0.412, 95% CI = 0.134 - 1.269), reviewing health record of semen prior to purchasing (OR = 0.492, 95% CI = 0.152 - 1.589), complete isolation of runt pigs (OR = 0.264, 95% CI = 0.084 - 0.829), compulsory registering for visitors (OR = 0.424, 95% CI = 0.111 - 1.612), keeping records of insecticide history (OR = 0.406, 95% CI = 0.089 - 1.846), routine on-farm monitoring by veterinarians (OR = 0.314, 95% CI = 0.069 - 1.423), and use of on-farm checklist for biosecurity monitoring (OR = 0.313, 95% CI = 0.063 - 1.553) were found to decrease the probability of PRRS infection. Multivariate and multilevel analysis revealed only two factors, complete isolation of runt pigs (OR = 0.165, 95% CI = 0.045 - 0.602 and OR = 0.208, 95% CI = 0.055 - 0.782) and compulsory registering for visitors (OR = 0.106, 95% CI = 0.017 - 0.655 and OR = 0.119, 95% CI = 0.017 - 0.809) were found to decrease the probability of PRRS infection. The intracluster correlation coefficient of a province for multilevel model was 0.05. The results of this study might facilitate biosecurity measures for individual farms to reduce the probability of PRRS infection.

• East Asian mathematical journal
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• 제33권4호
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• pp.333-351
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• 2017

Schools are expected to ultimately moderate the difference of inequality issues among social groups and reduce the achievement gaps. This study investigates this expectation, in particular, how students' mathematics achievements are influenced by their parents' education at the individual level and by collective responsibility for teaching at the school level as well as the interaction of the two. Using a two-level hierarchical linear model, this study indicates that a school collective responsibility has a larger positive effect on students' mathematics achievement when their parents' education level is high. This means that school's collective responsibility accelerates inequity in students' mathematics achievement. Knowing that collective responsibility has less of an effect on students whose parents' education is not high, researchers, schools, and school districts should continue to search for school effects that have more of a positive impact on the relationship between mathematics achievement for students whose parents' education is not high in order to have more equitable results for all students.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.725-728
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• 2004

In this study, the effect of mode II by variation of multilevel loading direction was experimentally investigated in the fatigue crack propagation behavior. To generate mixed-mode I+II loading state, the compact tension shear(CTS) specimen and loading device were used in this tests. The experimental method divided into three steps and three cases that were step I(0$^{\circ}$), step II(30$^{\circ}$, 60$^{\circ}$, 90$^{\circ}$),step III(0$^{\circ}$) and case I(0$^{\circ}$ ⇒ 30$^{\circ}$ ⇒ 0$^{\circ}$), case II(0$^{\circ}$ ⇒ 60$^{\circ}$ ⇒ 0$^{\circ}$), case III(0$^{\circ}$ ⇒ 90$^{\circ}$ ⇒ 0$^{\circ}$). The result of test, the step II affected to the step III in the all case. Specially, The fatigue crack propagation rate was faster and the fatigue life was smaller than of mixed mode I+II(30$^{\circ}$,60$^{\circ}$) due to the effect of mode II in the step III of the case III