• Journal of Korean Dental Science
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• v.12 no.1
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• pp.13-19
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• 2019

Purpose: The aim of this study was to compare the flexural strength of provisional fixed dental prostheses which was three-dimensional (3D) printed by several build directions. Materials and Methods: A metal jig with two abutment teeth and pontic space in the middle was fabricated. This jig was scanned with a desktop scanner and provisional restoration was designed on dental computer-aided design program. On the preprocessing software, the build angles of the restorations were arranged at $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ and support was added and resultant structure was sliced to a thickness of $100{\mu}m$. Processed restorations were printed with digital light processing type 3D printer using poly methyl meta acrylate-based resin. After washing and post-curing, compressive loading was applied at a speed of 1 mm/min on a metal jig fixed to a universal testing machine. The maximum pressure at which fracture occurred was measured. For the statistical analysis, build direction was set as the independent variable and fracture strength as the dependent variable. One-way analysis of variance and Tukey's post hoc analysis was conducted to compare fracture strength among groups (${\alpha}=0.05$). Result: The mean flexural strength of provisional restoration 3D printed with the build direction of $0^{\circ}$ was $1,053{\pm}168N$; it was $1,183{\pm}188N$ at $30^{\circ}$, $1,178{\pm}81N$ at $45^{\circ}$, $1,166{\pm}133N$ at $60^{\circ}$, and $949{\pm}170N$ at $90^{\circ}$. The group with a build direction of $90^{\circ}$ showed significantly lower flexural strength than other groups (P<0.05). The flexural strength was significantly higher when the build direction was $30^{\circ}$ than when it was $90^{\circ}$ (P<0.01). Conclusion: Among the build directions $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ set for 3D printing of fixed dental prosthesis, an orientation of $30^{\circ}$ is recommended as an effective build direction for 3D printing.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.274-283
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• 2019

Beta diversity is an efficient means of assessing the spatial variation in community composition among sites. To present fish community variation and LCBD (Local Contribution to Beta Diversity) among sites in stream, 6 sampling sites were selected in Cheonggye stream. Fish communities, environmental and habitat variables were collected at sites from April 2014 to October 2015. We used the total variance of the fish community data table (site-by-species community table) based on different forms, presence-absence, abundance, and Hellinger transformation, to estimate and compare beta diversity and LCBD. Fish community data table transformed by Hellinger distance showed the higher values of beta diversity than presence-absence and abundance data table. A similar patterns of LCBD were observed with presence-absence and Hellinger transformed data table. Low value of beta diversity calculated by community data table with abundance was due to the non-normality of fish assemblage data. Additionally, correlation coefficients were calculated to evaluate the relationships among LCBD, community indices and physicochemical variables. LCBD showed negative correlation coefficients with Shannon diversity. Overall, application of beta diversity analysis is an efficient method of addressing spatial variation of fish communities and ecological uniqueness of the sites in stream.

• 한국사회정책
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• v.23 no.2
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• pp.173-200
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• 2016

This study has two objectives. First, this study examines subjective well-being among elders that operationalize life satisfaction and aging anxiety, guided by life-course perspective. Second, it examines the relationship between subjective well-being and age-friendly environment factor structure among age-cohort groups. This study employs the stratified sampling method from 4,000 Seoul citizens. Main findings from the multivariate regression analyses include: (1) as age increases, aging anxiety levels appeared to be higher, while decreasing the life satisfaction. (2) a substantially larger variance of life satisfaction and aging anxiety was accounted for by demographic variables and age-friendly environments across age-cohort groups. (3) the influence of age-friendly environment factors such as neighborhood problems, accessibility to social activities, social services and parks on subjective well-being was different across age-cohort groups. This study discusses the policy and practical implications of the results.

• Journal of Life Science
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• v.32 no.10
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• pp.803-811
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• 2022

Despite the importance of traditional Korean fermented foods, little is known about the microbial communities and diversity of fermented soy products. To gain insight into the unexplored microbial communities of both Doenjang (DJ) and Ganjang (GJ) that may contribute to the fermentation in Korean traditional foods, we carried out next-generation sequencing (NGS) based on the V3-V4 region of 16S rDNA gene analysis. The alpha diversity analysis results revealed that both the Shannon and Simpson diversity indices were significantly different between the two groups, whereas the richness indices, including ACE, CHAO, and Jackknife, were not significant. Firmicutes were the most dominant phylum in both groups, but several taxa were found to be more abundant in DJ than in GJ. The proportions of Bacillus, Kroppenstedtia, Clostridium, and Pseudomonas and most halophiles and halotolerant bacteria, such as Tetragenococcus, Chromohalobacter, Lentibacillus, and Psychrobacter, were lower in DJ than in GJ. Linear discriminant effect size (LEfSe) analysis was carried out to discover discriminative functional biomarkers. Biomarker discovery results showed that Bacillus and Tetragenococcus were identified as the most important features for the classification of subjects to DJ and GJ. Paired-permutational multivariate analysis of variance (PERMANOVA) further revealed that the bacterial community structure between the two groups was statistically different (p=0.001).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5A
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• pp.433-442
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• 2010

A control of chloride diffusion coefficient is very essential for service life of reinforced concrete (RC) structures exposed to chloride attack so that much studies have been focused on this work. The purpose of this study is to derive the intended diffusion coefficient which satisfies intended service life and propose a technique for optimum concrete mixture through genetic algorithm(GA). For this study, 30 data with mixture proportions and related diffusion coefficients are analyzed. Utilizing 27 data, fitness function for diffusion coefficient is obtained with variables of water to binder ratio(W/B), weight of cement, mineral admixture(slag, flay ash, and silica fume), sand, and coarse aggregate. 3 data are used for verification of the results from GA. Average error from fitness function is observed to 18.7% for 27 data for diffusion coefficient with 16.0% of coefficient of variance. For the verification using 3 data, a range of error for mixture proportions through GA is evaluated to 0.3~9.3% in 3 given diffusion coefficients. Assuming the durability design parameters like intended service life, cover depth, surface chloride content, and replacement ratio of mineral admixture, target diffusion coefficient, where exterior conditions like relative humidity(R.H.) and temperature, is derived and optimum design mixtures for concrete are proposed. In this paper, applicability of GA is attempted for durability mixture design and the proposed technique would be improved with enhancement of comprehensive data set including wider range of diffusion coefficients.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.797-804
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• 2006

A development of regression model for asphalt concrete pavements using Falling Weight Deflectometer deflections is presented in this paper. A backcalculation program based on layered elastic theory was used to generate the synthetic modulus database, which was used to generate 95% confidence intervals of modulus in each layer. Using deflection basins of FWD data used in developing this procedure were collected from Pavement Management System in flexible pavements. Assumptions of back-calculation are that one is 3 layered flexible pavement structure and another is depth to bedrock is finite. It is found that difference of between 95% confidence intervals and modulus ranges of other papers does not exist. So, the data of 95% confidence intervals in each layer was used to develop multiple regression models. Multiple regression equations of each layer were established by SPSS, package of Statics analysis. These models were proved by regression diagnostics, which include case analysis, multi-collinearity analysis, influence diagnostics and analysis of variance. And these models have higher degree of coefficient of determination than 0.75. So this models were applied to predict modulus of domestic asphalt concrete pavement at FWD field test.

• Journal of Korea Entertainment Industry Association
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• v.13 no.7
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• pp.285-294
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• 2019

The purpose of this study is to assess construct validity and verify the concept of the Happiness-enhancing Activities and Positive Practices Inventory(HAPPI) developed by Henricksen & Stephens(2013), for Korean old adults who participating physical activities with measuring happiness-related propensity. In this study, the research model was confirmed by evidenced based on the content validity, EFA, construct validity of the latent structure analysis with CFA, reliability as internal consistency. Using self-reported questionnaire conducted among 370 participants who physical activities. Total of 344 data were selected. As a result, internal consistency α was acceptable. Evidence-based on convergent and discriminant of the CFA as GFI=.925, CFI .962, TLI .953, and RMSEA .062 appeared significantly. Model goodness-of-fit, C.R. ratio(Critical ratio: estimates/SE) and Squared Multiple Correlations(SMC), and average variance extracted(AVE) was verified with the hypothesis of the model. Therefore, HAPPI validity evidence for the model fit was confirmed. In conclusion, the HAPPI 4 factors and 16 items(Other-focused, Personal recreation and interests, Achievement, Self-Concordant Work, Spiritual and thought-related) has reliable evidence to apply for Korean old adults and applicable assessment of happiness.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.164-170
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• 2024

The light buoy, a floating structure at sea, is prone to drifting due to external factors such as oceanic weather. This makes it imperative to monitor for any loss or displacement of buoys. In order to address this issue, the Ministry of Oceans and Fisheries aims to issue alerts for buoy displacement by analyzing historical buoy position data to detect patterns. However, periodic lifting inspections, which are conducted every two years, disrupt the buoy's location pattern. As a result, new patterns need to be analyzed after each inspection for location monitoring. In this study, buoy position data from various periods were analyzed using convex hull and distance-based clustering algorithms. In addition, the optimal data collection period was identified in order to accurately recognize buoy location patterns. The findings suggest that a nine-week data collection period established stable location patterns, explaining approximately 89.8% of the variance in location data. These results can improve the management of light buoys based on location patterns and aid in the effective monitoring and early detection of buoy displacement.

• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.169-187
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• 1995

Contemporary US metropolitan areas have undergone divergent economic transformation, and as a result labor markets have become the focus of concern in their role as determinants of earnings attainment. Explanations of individual earnings attainmnent as a lobor market outcome have been established in two diafferent stances one who emphasizes personal or group attributes in the human capital perspective and the other who emphasizes economic structure in the labor market segmentation perspective. While remaining at the conceptual level and yet relatively unexplored, the importance of place in labormarket operation is a significant advancement as it appears in labor market areas and local labor markets considering that labor market areas represent the intersection of labor market structure and individual labor market experiences at specific geographic places. The substantive inquiry of this study was to explore labor market characteristics and their differentiation across large metropolitan areas, and assess their effects on the individual earnings attainment. Integating individual attributes and labor market characteristics as major factors of labor market operation, this study intended to contextualize individual earnings attainment with geographic labor market areas. Using 1990 US population census 5% "Public-Use Microdata Samples, " the largest 65 metropolitan areas were first selected and employed male workers who are aged between 25 and 50 for whites, blacks, asians, and hispanics. As an initial step earnings differentials between racial/ethnic groups and selected 65 metropolitan areas were examined using analysis of variance, and then earnings differentials were attributed to the individual attributes such as education, age, and immigration status, and four dimensions of metropolitan labor market differentiation devised by principal component analysis of industrial and occupational segments: Public versus Blue Collar Core(CS1), Finance-Core Utility versus Blue Collar Local Monopoly (CS2), Oligopoly versus Blue Collar Periphery(CS3), and Self Employed-White Collar Periphery versus Low-Skill Core(CS4). As a final analysis, individual earnings were related to each individual attribute and its interaction with metropolitan labor market characteristics to examine how the differentiated metropolitan labor market characteristics alter the role of individual attributes on earnings attainment. The findings indicated that individual attributes, education in particular exert significant effects on earnings attainment, but their effects were significantly altered by metropolitan labor market characterristics. Particularly important dimensions were: Oligopoly differentiated from Blue Colla Periphery metropolitan areas enhancing earnings returns to individual attributes for all groups but minority groups (black, asians, hispanics) rely more on this, and Finance-Core Utility differentiated from Blue Collar Local Monopoly metropolitan areas provide higher earnings returns to whites exclusively. These findings suggest that individuals with identical individual attributes involving racial/ethnic categories would have different earnings atteinments depending on the metropolitan labor market characteristics where they reside. Referring back to the major traditions of the human capital and the labor market segmentation in labor market research, the interaction between individual attributes and metropolitan labor market haracteristics on earnings attainment highlights the complimentary nature of the two on earnings determination in particular geographic places, Hence, labor market characteristics differentiatcd across metropolitan areas are an integral part of labor market operation which should be considered for the explanation of individual earnings attainment and racial/ethnic group earnings differentials. Gcographic places are the important contexts for labor market segmentation and individual labor market experiences. In conclusion, this study brings geographic labor markets to the forefront in the examination of individuals' earnings attainments. The empirical vaidation of the role of metropolitan labor market charecteristics on earnings attainment, while exploratory contributes towards a broader perspective of geographic labor market research that recognizes that individuals' labor market experiences are intertwined with geographic contexts of labor market operatin. operatin.

• Journal of Nutrition and Health
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• v.51 no.4
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• pp.340-356
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• 2018

Purpose: This study was conducted to develop a nutrition quotient (NQ) to assess overall dietary quality and food behaviors of Korean adults. Methods: The NQ was developed in three steps: item generation, item reduction, and validation. Candidate items of the NQ checklist were derived from a systematic literature review, expert in-depth interviews, statistical analyses of the Korea National Health and Nutrition Examination Survey (2010 ~ 2013) data, and national nutrition policies and recommendations. A total of 368 adults (19 ~ 64 years) participated in a one-day dietary record survey and responded to 43 items in the food behavior checklist. Pearson's correlation coefficients between responses to the checklist items and nutritional intake status of the adults were calculated. Item reduction was performed, and 24 items were selected for a nationwide survey. A total of 1,053 nationwide adult subjects completed the checklist questionnaires. Exploratory and confirmatory factor analyses were performed to develop a final NQ model. Results: The 21 checklist items were used as final items for NQ. Checklist items were composed of four factors: nutrition balance (seven items), food diversity (three items), moderation for the amount of food intake (six items), and dietary behavior (five items). The four-factor structure accounted for 41.8% of the total variance. Indicator tests of the NQ model suggested an adequate model fit (GRI = 0.9693, adjusted GFI = 0.9617, RMR = 0.0054, SRMR = 0.0897, p < 0.05), and item loadings were significant for all subscales. Standardized path coefficients were used as weights of the items. The NQ and four-factor scores were calculated according to the obtained weights of the questionnaire items. Conclusion: NQ for adults would be a useful tool for assessing adult dietary quality and food behavior. Further investigations of adult NQ are needed to reflect changes in their food behavior, environment, and prevalence of chronic diseases.