• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.231-240
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• 2018

Bamboo is one of the major biomass resources that have many advantages such as fast growing, easy cultivation, short rotation, and a relatively lower price. In this study, the anatomical characteristics of Moso bamboo (Phyllostachys pubescens) by age from one-year-old to five-year-old were examined by optical and scanning electron microscopy. Also, the crystalline properties such as relative crystallinity and crystallite width were investigated by an X-ray diffraction method. In one-year-old bamboo xylem, a few vascular bundles showed missing bundle sheath in near the intercellular space. Moreover, one-year-old bamboo had the shortest fiber length and the smallest values in vessel diameter, width of vascular bundle, and thickness of inner layer. One-year-old bamboo also showed the smallest values in the crystallinity and crystallite width. Near epidermis samples had longer fiber length and greater vascular bundle spacing than near pith samples. Relative crystallinity and crystallite width near the epidermis were also higher than near the pith. This study revealed significant differences in qualitative and quantitative anatomical characteristics between one-year-old and two-year- or more old Moso bamboos. It is concluded that the structural differences by bamboo age can be used to differentiate the characteristics of juvenile and mature bamboo.

• Allergy, Asthma & Immunology Research
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• v.10 no.6
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• pp.614-627
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• 2018

Purpose: Asthma is a heterogeneous disease that responds to medications to varying degrees. Cluster analyses have identified several phenotypes and variables related to fixed airway obstruction; however, few longitudinal studies of lung function have been performed on adult asthmatics. We investigated clinical, demographic, and inflammatory factors related to persistent airflow limitation based on lung function trajectories over 1 year. Methods: Serial post-bronchodilator forced expiratory volume (FEV) 1% values were obtained from 1,679 asthmatics who were followed up every 3 months for 1 year. First, a hierarchical cluster analysis was performed using Ward's method to generate a dendrogram for the optimum number of clusters using the complete post-FEV1 sets from 448 subjects. Then, a trajectory cluster analysis of serial post-FEV1 sets was performed using the k-means clustering for the longitudinal data trajectory method. Next, trajectory clustering for the serial post-FEV1 sets of a total of 1,679 asthmatics was performed after imputation of missing post-FEV1 values using regression methods. Results: Trajectories 1 and 2 were associated with normal lung function during the study period, and trajectory 3 was associated with a reversal to normal of the moderately decreased baseline FEV1 within 3 months. Trajectories 4 and 5 were associated with severe asthma with a marked reduction in baseline FEV1. However, the FEV1 associated with trajectory 4 was increased at 3 months, whereas the FEV1 associated with trajectory 5 was persistently disturbed over 1 year. Compared with trajectory 4, trajectory 5 was associated with older asthmatics with less atopy, a lower immunoglobulin E (IgE) level, sputum neutrophilia and higher dosages of oral steroids. In contrast, trajectory 4 was associated with higher sputum and blood eosinophil counts and more frequent exacerbations. Conclusions: Trajectory clustering analysis of FEV1 identified 5 distinct types, representing well-preserved to severely decreased FEV1. Persistent airflow obstruction may be related to non-atopy, a low IgE level, and older age accompanied by neutrophilic inflammation and low baseline FEV1 levels.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.486-495
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• 2021

Background: Particulate matter (PM) is one of the leading causes of premature death worldwide. Previous studies in South Korea have applied a relative risk calculated from Western populations when estimating the disease burden attributable to PM. However, the relative risk of PM on health outcomes may not be the same across different countries or regions. Objectives: This study aimed to estimate the premature deaths and socioeconomic costs attributable to long-term exposure to PM in South Korea. We considered not only the difference in PM concentration between regions, but also the difference in relative risk. Methods: National monitoring data of PM concentrations was obtained, and missing values were imputed using the AERMOD model and linear regression model. As a surrogate for relative risk, hazard ratios (HRs) of PM for cardiovascular and respiratory mortality were estimated using the National Health Insurance Service-National Sample Cohort. The nation was divided into five areas (metropolitan, central, southern, south-eastern, and Gangwon-do Province regions). The number of PM attributable deaths in 2018 was calculated at the district level. The socioeconomic cost was derived by multiplying the number of deaths and the statistical value of life. Results: The average PM₁₀ concentration for 2014~2018 was 45.2 ㎍/m³. The association between long-term exposure to PM₁₀ and mortality was heterogeneous between areas. When applying area-specific HRs, 23,811 premature deaths from cardiovascular and respiratory disease in 2018 were attributable to PM₁₀ (reference level 20 ㎍/m³). The corresponding socioeconomic cost was about 31 trillion won. These estimated values were higher than that when applying nationwide HRs. Conclusions: This study is the first research to estimate the premature mortality caused by long-term exposure to PM using relative risks derived from the national population. This study will help precisely identify the national and regional health burden attributed to PM and establish the priorities of air quality policy.

• Journal of Cadastre & Land InformatiX
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• v.49 no.1
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• pp.181-195
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• 2019

This study aims to analyze the spatial context by analyzing the flow characteristics of the walking tour course and visualizing effectively using the floating population data constructed through the communication data. The floating population data refinement algorithm was developed for estimation flow population along the road and the floating population data for each walking tour courses was constructed. In order to adopt the algorithm for forming suitable for the analysis of the walking tour courses, the estimation of floating population considering the area of the road and the estimation of floating population considering the value of floating population around the road were compared. As a result, the estimation of floating population considering ambient the values of flow population was adopted, which is more appropriate to apply analysis method due to the relatively consistent data. Then, a datamining algorithm for walking tour course was constructed according to the characteristics of the floating population data, the absence of missing values. Finally, this study analyzed the flow characteristics and spatial patterns of 18 walking trails in Seoul through the floating population data according to walking tour course. To do this, the kernel density analysis and the Getis-Ord $G^*_i$ statistical hotspot analysis were applied to visualize the main characteristics of each walking tour course.

• The Journal of Korean Society for School & Community Health Education
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• v.20 no.1
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• pp.15-27
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• 2019

Objective: Patients with COPD have a lower overall quality of life than normal people. If patients with COPD do not regularly perform physical activities, their exercise capacity is reduced. It could lead to muscle loss, and negatively affect their general physical, social, and psycho-social status. The purpose of this study was to examine association with physical activity, sedentary life time and health-related quality of life in patients with COPD. Method: Of the total of 22,948 participants surveyed in Korean National Health and Nutrition Examination Survey (KNHANES 2013-2015), 8,626 participants were used for this study. Of these, under 40 years, over 80 years, missing values and abnormal values were excluded. Study variables included physical activity level, sedentary time and health-related quality of life variables. The physical activity level assessment tool was measured using International Physical Activity Questionnaire (IPAQ). Sedentary time referred to the amount of sitting time without moving the body. EQ-5D (Euro Quality of Life-5 Dimensions) was used as an index of health-related quality of life. Control variables were age, gender, income level, education level, marital status, comorbidity, smoking, BMI, cough, sputum, COPD severity. For this study, descriptive analysis, T-test, ANOVA and multivariate regression analysis were performed. Results: Of the 1,092 patients with COPD, 76.1% (n=831) were male and 23.9% (n=261) were female, while 39.0% (n=2,939) were male and 61.0% (n=4,595) were female in the comparison group without COPD. The COPD group with high level of physical activity showed a high level of EQ-5D scores ($0.9349{\pm}0.11$, p <0.001). Among patients with COPD, after adjusting for control variables, physical activity and sedentary time (physical activity level, Β=0.047, p <.001), (sedentary time, Β=-0.017, p <.05) were associated with health-related quality of life. Conclusion: Patients with COPD have a higher quality of life as their physical activity increases and the quality of life decreases as the time spent sitting increases. This study suggests that public health experts should consider improving COPD patient physical activity.

• Journal of Korea Water Resources Association
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• v.57 no.3
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• pp.209-223
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• 2024

In the context of the fourth industrial revolution, data-driven decision-making has increasingly become pivotal. However, the integrity of data analysis is compromised if data quality is not adequately ensured, potentially leading to biased interpretations. This is particularly critical for water level data, essential for water resource management, which often encounters quality issues such as missing values, spikes, and noise. This study addresses the challenge of noise-induced data quality deterioration, which complicates trend analysis and may produce anomalous outliers. To mitigate this issue, we propose a noise removal strategy employing Wavelet Transform, a technique renowned for its efficacy in signal processing and noise elimination. The advantage of Wavelet Transform lies in its operational efficiency - it reduces both time and costs as it obviates the need for acquiring the true values of collected data. This study conducted a comparative performance evaluation between our Wavelet Transform-based approach and the Denoising Autoencoder, a prominent machine learning method for noise reduction.. The findings demonstrate that the Coiflets wavelet function outperforms the Denoising Autoencoder across various metrics, including Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Mean Squared Error (MSE). The superiority of the Coiflets function suggests that selecting an appropriate wavelet function tailored to the specific application environment can effectively address data quality issues caused by noise. This study underscores the potential of Wavelet Transform as a robust tool for enhancing the quality of water level data, thereby contributing to the reliability of water resource management decisions.

• Journal of Nutrition and Health
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• v.53 no.3
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• pp.271-287
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• 2020

Purpose: Variations in the iodine contents of foods is critical for estimating the iodine intake. This study aimed to update the iodine database of common Korean foods and evaluated the iodine intake in Korean adults. Methods: A list of 855 Korean foods was selected for the updated iodine database. The updated database was established with Version 1 and 2 by applying an average or minimum value for the imputed values. The iodine intake was estimated in 5,927 Korean adults using the data from the 2013-2015 Korea National Health and Nutrition Examination Survey. Results: The analytical values in the updated database were 166 (19.4%), followed in order by 318 (37.2%), 247 (28.9%), and 124 (14.5%) for the adapted, imputed, and missing values, respectively. The median of dietary iodine intake was 352.1 ㎍/day (± 2,166.1) and 343.4 ㎍/day (± 2,161.9) in Version 1 and 2 among the total population. The contribution rates of each food group to the iodine intake were 55.7% for seaweeds, which showed a similar trend in Version 2. When subjects were divided by consumption of seaweeds, the median iodine intake was 495.7 ㎍ in the consumer group, which was almost double (241.2 ㎍) that of the non-consumer group. The proportion of subjects who consumed below the Estimated Average Requirement of iodine was 11.0% in the non-consumer group. In contrast, 11.6% in the consumer group of seaweed consumed above the Upper Level of iodine. When the dietary iodine and urinary iodine were examined, the regression coefficient was 0.11718 in Version 1 and 0.11512 in Version 2 after adjusting for age and sex. Conclusion: This study presented the variation of iodine intake in Korean adults by applying different versions of the iodine database. As the iodine intake can vary due to the highly variable concentrations in the major food sources, an iodine database is necessary to be monitored, and caution should be taken when the database is used in research.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.4
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• pp.55-64
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• 2014

While small and medium-sized companies are suffering from a shortage of workers as a result of social tendency to avoid those companies, college graduates still prefer large companies or governmental positions, which consequently results in inconsistencies in the demand and supply of work forces. The gap between them is getting so bad that employment difficulties are exacerbating. Accordingly this study tries to search for potential employee's expected value factors which make people select small and medium companies not big companies. A survey was conducted from October 1 to october 30, 2012 with university students in the Seoul metropolitan area. a total of 350 questionnaires were distributed and 335 were collected. of these, 332 questionnaires were used for data analyses excluding questionnaires with missing values. Data was analyzed by frequency, descriptive factor, reliability, and regression with SPSS win 18.0 program The result of this study were as follows. A factor analysis extracted four factors comprising small and medium companies, which we named career(factor 1), working environment(factor 2), working achievement(factor 3), job security (factor 4). This study showed that small and medium companies' preference were affected by the career, working environment, job security, corporate reputation, salary.

• Culinary science and hospitality research
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• v.20 no.2
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• pp.1-15
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• 2014

This study aims to empirically analyze the influence of emotional leadership of hotel cuisine employees on empowerment, trust and innovative behavior. Selecting cooks working for ten five-star hotels in Seoul for empirical analysis, total 500 copies of questionnaire (50 copies to each hotel) were distributed for 30 days from September $23^{rd}$ to October $22^{nd}$, 2013. Excluding the ones with missing values or too much weighted tendency, total 426 copies(85.2%) were used as the final data for statistical analysis. As a result of the analysis, the verification of causal relationships between hotel cuisine employees' perceived emotional leadership and empowerment, trust and innovative behavior within organizations is valuable enough to be used as the theoretical foundation in the future. Based on the results of such in-depth analysis, hotel cuisine employees' perceived emotional leadership can be shown through interactions between leaders and employees. The effectiveness of leadership can be maximized only when leaders and employees maintain the mutual cooperative partnership to lead employees' innovative behavior by implanting empowerment and trust in employees.

• Culinary science and hospitality research
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• v.22 no.3
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• pp.121-138
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• 2016

This study is intended to present effective career guidance and direction by identifying the various factors involved in the career preparation behavior for the improvement of the employment rate of culinary and foodservice management major field students. This study was established on the hypothesis of a structural relationship that career decision-making self-efficacy develops career maturity and career preparation behavior on the basis of social cognitive career theory, which was verified through empirical analysis. Out of 450 survey responses from by Culinary and Foodservice Management Major Students, a total of 302 questionnaires were used for the final analysis due to missing values and biased responses(response rate: 83.6%). Collected data were identified using SPSS 16.0 and AMOS 5.0. A higher-order factor model was employed (High-order model) before a confirmatory factor analysis, and this study examined its reliability and validity analysis for hypothesis testing. Career decision-making self-efficacy had positive effects on career maturity(t=6.86, p<0.001) and career preparation behavior(t=3.83, p<0.001), and career maturity had positive effects on career preparation behavior (t=2.79, p<0.01). As a result, all hypotheses were accepted. These results confirmed that strengthening students' faith in themselves with competencies is core competencies with career-related issue can be the driving force that can enable students to develop into mature professionals. Therefore, this study suggests an awareness of the importance of career decision-making self efficacy and proposes a need for a systematic and integrated career counseling program that can improve it.