• The Journal of Korean Society for School & Community Health Education
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• v.25 no.2
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• pp.27-44
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• 2024

Objectives: This study aimed to provide foundational data for preventing adolescents smoking by analyzing the relationship between adolescents' lifestyles and smoking experiences and identifying influencing factors. Methods: Secondary data analysis was conducted using the 17th (2021) Youth Health Behavior Survey data, encompassing 54,848 students from 796 schools. Variables included general characteristics, smoking status, lifestyle habits, physical activity, sleep patterns, and stress perception. Frequency analysis was used to examine general characteristics, while further analysis employed frequency analysis and the Pearson Chi-square test to compare lifestyle differences based on smoking presence. Multinomial logistic regression analysis was employed to determine factors influencing smoking experience, with IBM SPSS Statistics 28 used for all analyses at a significance level of p<.05. Results: Analysis revealed with general characteristics that the group with smoking experience exhibited a higher proportion of male students (67.4%) compared to the non-smoking group (50.1%) (p<.001). Analysis revealed that the smoking group was more likely to skip breakfast (27.7%), not consume fruit (17.8%), and consume fast food more than three times daily (0.9%). Furthermore, a higher percentage of smokers engaged in 60 minutes or more of breathless physical activity (8.4%) seven times a week, reported insufficient fatigue recovery through sleep (21.6%), and experienced very severe normal stress (17.2%) (p<.001). Analysis of the relationship between lifestyle and smoking indicated increased likelihood of smoking with zero breakfast consumption (OR=1.759, p<.001) and increased fruit consumption (OR=1.921, p<.001), while zero fast food consumption decreased smoking likelihood (OR=0.206, p<.001). Adequate sleep-related fatigue recovery reduced smoking likelihood (OR=0.458, p<.001), whereas increased stress elevated it (OR=1.260, p<.05). Conclusion: Adolescents' lifestyle habits significantly correlated with their smoking experiences, highlighting the necessity of considering lifestyle factors in smoking prevention strategies. This study provides crucial insights for promoting healthy lifestyle changes to prevent smoking among youth.

• Tuberculosis and Respiratory Diseases
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• v.42 no.6
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• pp.900-912
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• 1995

Background: Although graded exercise stress tests are widely used for the evaluation of cardiorespiratory performance, normal standards on respiratory gas exchange and ventilatory functions at maximal exercise in Koreans have not been well established. The purpose of this study is to provide reference values on these by sex and age, along with derivation of some of their prediction equations. Method: Symptom-limited maximal exercise test was carried out by Bruce protocol in 1,000 healthy adults consisting of 603 males and 397 females, aged 20~66 years. Among them VC, $FEV_1$ and MVV were also determined in 885 cases. All the subjects were members of a health center, excluding athletes. During the exercise, subjects were allowed to hold on to front hand rail of the treadmill for safety purpose. Results: The $VO_2\;max/m^2$, $VCO_2\;max/m^2$ and $V_E\;max/m^2$ were greater in males than in females and decreased with age. The RR max in men and women was similar but decreased slightly with age. The $V_T$ max was markedly greater in men but showed no significant changes with age in either gender. The mean of $V_T$ max/VC, $V_E$ max/MVV and BR revealed that there were considerable ventilatory reserves at maximal exercise even in older females. The regression equations of the cardinal parameters obtained using exercise time(ET, min), age(A, yr), height(Ht, cm), weight(W, kg), sex(S, 0=male; 1=female), VC(L), $FEV_1$(L) and $V_E$ max(L) as variables are as follows: $VO_2\;max/m^2$(L/min)=1.449+0.073 ET-0.007A+0.010W-0.006Ht-0.209S, $VCO_2\;max/m^2$(L/min)=1.672+0.063ET-0.008A+0.010W-0.005Ht-0.319S, VE max/$m^2$(L/min)=58.161+1.503ET-0.315A-9.871S or VE max/$m^2$(L/min)=47.873+6.548 $FEV_1$-5.715 S, and VT max(L)=1.497+0.223VC-0.493S. Conclusion: Respiratory gas exchange and ventilatory variables at maximal exercise were studied in 1,000 non-athletes by Bruce protocol. During exercise, the subjects were allowed to hold on to hand rail of the treadmill for safety purpose. We feel that our results would provide ideal target values for patients and healthy individuals to be achieved, since our study subjects were members of a health center whose physical fitness levels were presumably higher than ordinary population.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.437-447
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• 2011

In this study, the lower limbs joints were analyzed for features based on the biomechanical characteristics of landing techniques according to height and landing on the ground type (flats and downhill). In order to achieve the objectives of the study, changes were analyzed in detail contents such as the height and form of the first landing on the ground at different angles of joints, torso and legs, torso and legs of the difference in the range of angular motion of the joint, the maximum angular difference between joints, the lower limbs joints difference between the maximum moment and the difference between COM changes. The subjects in this study do not last six months did not experience joint injuries 10 males in 20 aged were tested. Experimental tools to analyze were the recording and video equipment. Samsung's SCH-650A model camera was used six units, and the 2 GRF-based AMTI were used BP400800 model. 6-unit-camera synchronized with LED (photo cell) and Line Lock system were used. the output from the camera and the ground reaction force based on the data to synchronize A/D Syc. box was used. To calculate the coordinates of three-dimensional space, $1m{\times}3m{\times}2m$ (X, Y, Z axis) to the size of the control points attached to the framework of 36 markers were used, and 29 where the body was taken by attaching a marker to the surface. Two kinds of land condition, 40cm and 60cm in height, and ground conditions in the form of two kinds of flat and downhill slopes ($10^{\circ}$) of the landing operation was performed and each subject's 3 mean two-way RM ANOVA in SPSS 18.0 was used and this time, all the significant level was set at a=.05. Consequently, analyzing the landing technique as land form and land on the ground, the changes of external environmental factors, and the lower limbs joints' function in the evaluation were significantly different from the slopes. Landing of the slop plane were more load on the joints than landing of plane. Especially, knee extensor moment compared to the two kinds of landing, slopes plane were approximately two times higher than flat plane, and it was statistical significance. Most of all not so much range of motion and angular velocity of the shock to reduce stress was important. In the further research, front landing as well as various direction of motion of kinetic, kinetic factors and EMG variables on lower limbs joints of the study in terms of injury-prevention-approach is going to be needed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.975-981
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• 2013

A robust optimization is only one of the ways to minimize the effects of variances in design variables on the objective functions at the preliminary design stage. To predict the variances and to formulate the probabilistic constraints are the most important procedures for the robust optimization formulation. Though several methods such as the process capability index and the six sigma technique were proposed for the prediction and formulation of the variances and probabilistic constraints, respectively, there are few attempts using a percent defective which has been widely applied in the quality control of the manufacturing process for probabilistic constraints. In this study, the robust optimization for a lower control arm of automobile vehicle was carried out, in which the design space showing the mean and variance sensitivity of weight and stress was explored before robust optimization for a lower control arm. The 2nd order Taylor expansion for calculating the standard deviation was used to improve the numerical accuracy for predicting the variances. Simplex algorithm which does not use the gradient information in optimization was used to convert constrained optimization into unconstrained one in robust optimization.

• Journal of Korean Academy of Nursing
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• v.36 no.4
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• pp.596-603
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• 2006

Purpose. This study examined Korean clinical nurses' intentions to care for SARS patients and identify determinants of the intentions. Theory of planned behavior was the framework to explain the intentions of Korean nurses for SARS patients care. Methods. A convenient sample of six hundreds and seventy nine clinical nurses from four university-affiliated hospitals located in Seoul and in Kyung-gi province was used. Self-administered (83-items) questionnaire was used to collect data. Intentions, attitude, subjective norm, perceive behavioral control, behavioral beliefs, normative beliefs, and control beliefs were the study variables. All items were measured using 7point Likert scale (-3 to +3). Data were analyzed using descriptive statistics, Pearson correlation method, and stepwise multiple regression methods. Results. Intentions and attitudes toward SARS patient care among Korean clinical nurses were moderate, but their subjective norm and perceive behavioral control of SARS patients care were negative. Stepwise multiple regression analysis indicated that attitude toward SARS patient care, perceived behavioral control, subjective norm were the determinants of the intentions for SARS patients care as theory proposed. Among the behavioral beliefs, 'SARS-patient caring would be a new experience', 'during SARS-patient caring, I should be apart from my family', 'after completing SARS-patient caring, I would be proud of myself being able to cope with a stressful event' and 'with my SARS-patient caring, patients could recover from SARS' were the significant determinants. Among the normative beliefs, colleague approval, spouse approval, and physician approval were significant determinants of the intentions. Among the control beliefs, 'SARS-patient caring would be a challenge' 'SARS-patient caring is a professional responsibility', 'tension during the care of SARS patients' and 'support from team members' were the significant determinants of the intentions. Conclusions. Korean clinical nurses in this study were not willing to care for SARS patients and showed negative attitude toward the care. They believed their friends and family were not approved their care for SARS patients. Nurses were in conflicts between professional responsibilities to care for SARS patients and personal safety. This study was the first to understand stress and burden of Korean clinical nurses who are in front line to care for newly developed communicable disease such as SARS. Under the circumstance where several fatal communicable diseases are predictable, conflicts between professional responsibility and their personal risks should be taken into considerations by nurses themselves and by nursing administrators in order to improve quality of care.

• Journal of Convergence for Information Technology
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• v.10 no.9
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• pp.88-101
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• 2020

This study was conducted to identify the factors predicting binge drinking in men and women in Korea based on the results of the 7th year 3rd National Health and Nutrition Survey. The study data used the demographic and health-related characteristics and drinking characteristics of the National Health and Nutrition Survey, and were analyzed by cross-sample analysis and logistic regression analysis. As a result of the study, age (M:p=.003, F:p<.001), drinking frequency for one year (M:p<.001, F:p<.001), amount of alcohol consumed at a time (M:p<.001) 001, F:p<.001), family/doctor's recommendation for moderation (M:p<.001, F:p<.001), stress (M:p=.025, F:p<.001), Smoking (M:p<.001, F:p<.001) were predictors for binge drinking in both men and women. In addition, education level(p=.030) and economic activity status(p=.018) for men, income level(p<.001) and marital status(p=.020) for women were identified as predictors of binge drinking, and variables explained 72.4%(p < .001) and 74.5%(p < .001) of adult male and female binge drinking. This study is meaningful in that it provided basic data on the establishment of a gender-specific binge drinking prevention policy and the restructuring of drinking culture by clarifying that the risk factors of binge drinking in Korean adults differ by gender.

• Korean Journal of Childcare and Education
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• v.11 no.4
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• pp.63-79
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• 2015

This study explored the effect of mother's employment status on family environment and physical environment and psychological environment, the main concern of this which factors have effects on marital satisfactions of either employed or non-employed mothers. First, the result of analysis on family environment according to mothers' employment status shows non-employed mother's parental stress is higher than employed mother's. Besides, non-employed mother's self-esteem is lower than employed mother's, and non-employed mother's depression is significantly high. Concerning fathers' factors, the level of conflict between husband and wife is higher among husbands when their wives are employed. In the light of childrens' factors, non-employed mothers consider that their children display more negative emotion and more picky. Children's development of employed mothers is included in normal development range more than that of non-employed mothers. Second, conflict between husbands and wives have an significantly negative effect on marital satisfaction regardless wife's employment status. Husbands' cooperation in child-rearing and marital satisfaction have a positive effect on wives' marital satisfaction. The significant factor which influences on employed mother's marital satisfaction is education level of wives. This study would be meaningful in that infancy home environment was compared focusing on the mothers' employment status, and some factors which factors(variables) have impacts on marital satisfaction of infancy mothers were examined.

• Journal of Nutrition and Health
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• v.53 no.3
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• pp.255-270
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• 2020

Purpose: The purpose of this study was to identify the factors that influence the consumption of convenience foods among Korean adolescents. Methods: This study had a descriptive cross-sectional study. Data were obtained from the 15th (2019) Korea Youth Risk Behavior Web-based Survey, which involved a nationwide representative sample of 57,303 middle- and high-school students. Convenience-food consumption was defined by frequency of adolescents consuming convenience foods obtained from convenience stores, supermarkets, and cafeterias over the previous 7 days. The analyzed variables were related to sociodemographic, mental health, and health behavior. The Rao-Scott χ² test was applied to examine the difference in the rate of consuming convenience foods obtained from convenience stores according to each factor. Hierarchical logistic regression was conducted to examine the factors that influence convenience-food consumption among Korean adolescents. Results: It was found that 29.1% of Korean adolescents consumed convenience foods obtained from convenience store more than three times per week. The significant influencing factors were female sex; low subjective academic achievement, and subjective household economic status; high perceived stress; low subjective sleep sufficiency; experience of depression; suicidal ideation; lower physical activity; skipping breakfast; lower consumptions of fruit, milk, and vegetables; higher consumptions of soda drinks, sweet drinks, caffeine, and fast food; lower water intake; current smoking and drinking; drug use; and experience of violence. Conclusion: These findings provide a better understanding of the sociodemographic, mental-health, and health-behavior factors that influence the consumption of convenience foods among Korean adolescents. We suggest that differentiated policies, strategies, and nutrition education need to be developed and implemented, in order to address the above-mentioned factors and thereby reduce such behaviors among Korean adolescents.

• Journal of the Korean Society for Railway
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• v.19 no.6
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• pp.717-726
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• 2016

Emergency tracks are necessary in case a broken down train evacuates, a train needs to make way for a faster train behind it, or a train suddenly stops and following trains must avoid colliding with it. Magnetic Levitated (maglev) Trains can change track to enter an emergency track using a segmented switch or a traverse switch. On a traverse switch, a train can change its track when the part of the track that the train is on moves to the other track. Currently manufactured Maglev trains have two bodies and the total length is 25 meters. If a traverse switch is used, it will only require 30 meters of track to move the train to the other track, so, when it comes to efficiency of costs and space, the traverse switch surpasses the articulated switch. Therefore, in this paper, an optimized design to secure structural safety and weight lightening is suggested. To achieve these results, the heights of the piled concrete and girders which are both placed on the top of the traverse switch, are set as design variables. The Finite Element Method (FEM), in application of kriging and in the design of the experiments (DOE), is used. Maximum stress, deformation, and structural weight are compared with the results, and through this process structural safety and weight lightening is proven.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.4
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• pp.152-158
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• 2018

PVT (Physical Vapor Transport) method has advantages in producing high quality, large scale wafers where many researches are being carried out to commercialize nitride semiconductors. However, complex process variables cause various defects when it had non-equilibrium growth conditions. Annealing process after crystal growth has been widely used to enhance the crystallinity. It is important to set appropriate temperature, pressure, and annealing time to improve crystallinity effectively. In this study, the effect of the annealing conditions on the crystalline structure variation of the AlN single crystal grown by PVT method was investigated with synchrotron whitebeam X-ray topography, electron backscattered diffraction (EBSD), and Rietveld refinement. X-ray topography analysis showed secondary phases, sub-grains, impurities including carbon inclusion in the single crystal before annealing. EBSD analyses identified that sub-grains with slightly tilted basal plane appeared and the overall number of grains increased after the annealing process. Rietveld refinement showed that the stress caused by the temperature gradient during the annealing process between top and bottom in the hot zone not only causes distortion of grains but also changes the lattice constant.