• Journal of Industrial Convergence
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• v.22 no.2
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• pp.153-159
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• 2024

This study is a descriptive research study to determine the relationship between middle-aged women's social support, resilience and quality of life, and to identify factors that affect quality of life. The participants were 162 middle-aged women in G City. Data was collected from May 10 to June 10, 2023. Data were analyzed through descriptive statistics, t-test, one-way ANOVA, Pearson's correlation coefficient, and multiple regression using SPSS 25.0 program. The social support was 3.36±0.38, resilience was 3.39±0.42, and quality of life was 3.18±0.50. Quality of life was positively correlated with social support(r=.502, p<.001), resilience(r=.530, p<.001). Factors that have a significant impact on quality of life include resilience(β=.422, p<.001), social support(β=.412, p<.001) and health status(β=.212, p=.001). The total explanatory power of these variables on quality of life was 39.2%. Therefore, it is necessary to develop effective programs and strategies to improve the quality of life of middle-aged women by improving their resilience, social support, and health status.

• Journal of Environmental Health Sciences
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• v.50 no.2
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• pp.157-167
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• 2024

Background: Several previous studies have shown that commuting is a source of stress for undergraduate students. However, few studies have investigated the effect of commuting on academic stress among undergraduate students, and there has been little awareness of the environmental impact of commuting. Objectives: To evaluate the associations between commute type and/or time and academic stress among undergraduate students in South Korea, focusing on environmental sustainability. Methods: We conducted an online survey and obtained information on commute types, commute times, and academic stress from 510 undergraduate students aged ≥19 years. Academic stress was comprised of five sub-categories of stress, and total academic stress ranged from 5 to 25 points. Multiple linear regression analysis was used to analyze the associations between commute type and commute time and academic stress. Furthermore, the students were grouped into 21 categories based on their transportation mode for commuting. CO₂ emission factors per each commuting category were calculated using the transportation type's CO₂ emission data from previous studies. Spearman's correlation analysis was used to confirm the correlation between CO₂ emission factors and total academic stress. Results: Students using home-to-school transportation without transfers (vs. walking) showed a significantly higher total academic stress of 2.19 points (95% CI: 0.58, 3.80). In contrast, students using school-to-home transportation without transfers (vs. walking) showed a significantly lower total academic stress of 1.96 points (95% CI: -3.55, -0.38). Moreover, students using transportation with lower CO₂ emission factors had lower academic stress scores (home-to-school: correlation coefficient = 0.507, p<0.001; school-to-home: correlation coefficient = 0.491, p<0.001). Conclusions: Our findings suggest that both commute type and time are significantly associated with academic stress among South Korean undergraduate students. When students select environmentally-friendly transportation, they may not only improve their mental health but also improve climate resilience.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.37-47
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• 2024

This study proposes a track maintenance quantity estimation model that considers evolution of rail fatigue damage and ballast settlement based on actual maintenance data from the Gyeongbu high-speed railway, and revises the existing life cycle cost (LCC) model for railway track. Using this model, maintenance quantities and life cycle costs based on different track quality levels are evaluated and discussed. According to the results, it is confirmed that applying the track maintenance quantity estimation model that accounts for rail fatigue damage and ballast settlement allows us to reasonably estimate maintenance costs close to the actual data. The track quality coefficient significantly influences both rail and ballast maintenance quantities, with ballast maintenance having a greater impact than rail maintenance. Additionally, as train speed increases, both rail and ballast maintenance quantities rise. Moreover, a higher track quality coefficient leads to a steeper increase in maintenance quantities with increasing train speed. Consequently, LCC also exhibits a faster growth rate over time with higher track quality coefficients and faster train speeds, resulting from an increased proportion of maintenance costs.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.819-826
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• 2024

This study aims to examine the correlations between self-control, time management behavior, and SNS addiction proneness among university students, and to analyze their impact on academic procrastination. The goal is to explore intervention strategies to improve academic procrastination behaviors. The subjects of this study were 167 students from a university located in City D, who agreed to participate and responded to the survey between February 6, 2024, and April 19, 2024. The collected data were analyzed using the SPSS 21.0 statistical program, employing t-test, ANOVA, Pearson's correlation coefficient, and multiple regression analysis. Academic procrastination showed significant negative correlations with self-control (r=-.570, p<.001) and time management behavior (r=-.544, p<.001), and a significant positive correlation with SNS addiction proneness (r=.367, p<.001). The factors influencing academic procrastination were time management behavior (β=-.461, p<.001), self-control (β=-.359, p<.001), and SNS addiction proneness (β=.199, p<.001), with an explanatory power of 52%. To reduce academic procrastination among university students, it is necessary to implement various extracurricular programs aimed at improving time management behavior.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.1-6
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• 2007

In this study, we have performed the channel modification of the conventional MHEMT (metamorphic high electron mobility transistor) to improve the breakdown characteristics. The Modified channel consists of the InxGal-xAs channel and the InP sub channel instead of the InxGa1-xAs channel. Since InP has the lower impact ionization coefficient in comparison with In0.53Ga0.47As, we have adopted the InP-composite channel in the modified MHEMT. We have investigated the breakdown mechanism and the RF characteristics for the conventional and the InP- composite channel MHEMTs. From the measurement results, we have obtained the enhanced on and off-state breakdown voltages of 2.4 and 5.7 V, respectively. Also, the increased RF characteristics have brought about the decreased output conductance for the InP-composite channel MHEMT. The cut-off frequency (fT) and the maximum oscillation frequency (fmax) for the InP-composite Channel MHEMT were 160 GHz and 230 GHz, respectively. It has been shown that the InP-composite channel MHEMT has the potential applications for the millimeter wave power device.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.637-644
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• 2012

In a nuclear power plant, fretting wear due to impact motion between U-tubes and support structures located in steam generators can cause serious problems. In order to guarantee the reliability of the steam generator, the damage due to fretting wear should be thoroughly investigated. The purpose of this study is to elucidate the fretting wear mechanism qualitatively and quantitatively. Hence, fretting wear simulation is performed for the environments to which the actual steam generators in nuclear power plants are exposed. Initial experimental results are obtained for various experimental parameters, and the effect of the work rate and temperature on fretting wear is evaluated. In water, the wear coefficients for $90^{\circ}C$, $200^{\circ}C$, and $340^{\circ}C$ are found to be $9.051{\times}10^{-16}\;Pa^{-1}$, $3.009{\times}10^{-15}\;Pa^{-1}$, and $2.235{\times}10^{-15}\;Pa^{-1}$, respectively. It is also found that the wear coefficient at room temperature is larger than that at low temperature in water because of the dynamic viscosity of water.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.100-103
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• 2004

Experiments and simulation were done to study the impact of contrast agent when CT scan was used to attenuation correction for PET images in PET/CT system. Whole body phantom was imaged with various concentration of iodine-based contrast agent using CT. Mathematical emission and transmission density map with liver were made to simulate for whole body FDG imaging. Various transmission density maps was generated with non-uniform enhancement of contrast agent, hypo-attenuating of contrast agent for tumor, different concentration of contrast agent, and so on. Attenuation correction was done with all transmission maps. In the experiments, we confirmed that attenuation coefficient was changed by concentration of contrast agent. From the simulation data, image quality of attenuation corrected images was affected by contrast agent and artifact was produced by contrast agent. These results indicated that the contrast agent should be used with a full understanding of its potential problem in PET/CT system.

• Journal of Environmental Impact Assessment
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• v.26 no.1
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• pp.11-26
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• 2017

Approximate empirical equations obtained by measuring overall noise levels at different distances have been used to evaluate environmental influence of the railway noise though the accurate prediction of noise levels is important. In this paper, a noise prediction model considering the frequency characteristics of noise sources and propagation was suggested to improve the accuracy of noise prediction. The railway noise source was assorted into track, wheel, traction and aerodynamic components and they were characterized with the source strength and speed coefficient at each octave-band frequency. Correction terms for the acoustic roughness and the track/bridge condition were introduced. The sound attenuation from a source to a receiver was calculated taking account of the geometrical divergence, atmospheric absorption, ground effect, diffraction at obstacles and directivity of source by applying ISO 9613-2. For obtaining the source strength and speed coefficients, the results of rolling noise model, numerical analysis and measurements of pass-by noise were analyzed. We compared the predicted and measured noise levels in various vehicles and tracks, and verified the accuracy of the present model. It is found that the present model gives less error than the conventional one, so that it can be applied to make the accurate prediction of railway noise effect and establish its countermeasures efficiently.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.407-416
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• 2010

The purpose of this study was to examine the relationship among women's leisure dance participation, physical image and self-esteem. The subjects in this study were 300 female adults who were selected by cluster sampling from the population that consisted of women who were in their 20s to 50s. In the population, some women got leisure dance at fitness clubs, sport lovers' clubs and dance academies in Seoul and Gyeoggn Province as of 2009, and the others didn't. As for the reliability of the questionnaires used in the study, the Cronbach alpha coefficient of the questionnaires was above .70. The major statistical methods utilized in this study were Frequencies, reliability factor analysis, analysis covariate, regression analysis and path analysis. The findings of the study were as follows: First, the women who got leisuer dance evaluated their own physical image and self-esteem more favorably than the others who didn't. Second, the length of participation affected the body shape, satisfaction level and flexibility, and the intensity of participation impacted on the body shape and muscular power. Third, the length of participation had an impact on self-esteem, and the frequency of participation exerted a negative influence on that. Fourth, the degree of participation had a causal impact on physical image and self-esteem. In other words, the degree of getting leisure dance affected self-esteem in a firsthand manner and exerted a secondhand influence on that through physical image as well. The findings of the study suggested that physical image was one of major parameters to link participation in rhythmic exercise and self-esteem.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.463-473
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• 2018

This investigation was a descriptive study that examined the relationship among factors including professional autonomy, role conflict, and clinical decision-making ability of nurses on comprehensive nursing service wards. To accomplish this, a survey of 234 nurses working at D city and G city who were selected based on convenience sampling was conducted. Data were collected using a self-reported questionnaire completed by 234 nurses at four clinical hospitals from October 12, 2017 to November 30, 2017. The collected data were evaluated by t-tests, ANOVA, Pearson's correlation and stepwise multiple regression analysis. The mean clinical decision-making ability score was $3.38{\pm}0.78$, which corresponded to an intermediate level of clinical decision-making ability. Clinical decision making ability was positively correlated with professional autonomy, but role conflict showed a negative correlation. The factors having the greatest impact on clinical decision-making ability were found to be, in order, length of work, education level, professional autonomy and role conflict, which together accounted for 38.7% of the total impact. To improve clinical decision making ability, it is important to improve autonomy and role conflict. Additionally, to improve clinical decision-making ability, it is necessary to improve clinical decision-making ability to determine nurses tasks through professional autonomy and role conflict. Overall, the results of this study can be utilized as baseline data when developing a program to enhance nurses' clinical decision making ability. Moreover, it is suggested that an interventional study analyzing validity and effectiveness of developed education programs be conducted.