• Korean Journal of Family Social Work
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• no.55
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• pp.237-264
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• 2017

This study empirically tests whether community participation has a positive effect on parenting efficacy among marriage immigrant women in South Korea. The 3rd wave of the Gyoenggi Education Welfare Panel data was used, which includes 396 marriage immigrant women residing in Gyoenggi Province. Findings of hierarchical multiple regression analyses suggested that higher Korean language proficiency, shorter duration of residency, lower parenting stress and more positive family environment were associated with higher parenting efficacy. Community participation level had a statistically significant and positive impact on parenting efficacy, even after controlling for other variables. The type of community activities did not have significant impact on parenting efficacy, except for children's school activities, which had a negative impact on parenting efficacy. Implications for social work practice are discussed.

• Safety and Health at Work
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• v.10 no.1
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• pp.54-60
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• 2019

Background: Increasing the establishment of integrated management systems (IMSs) is done with the purpose of leaving traditional management methods and replacing them with modern management methods. Thus, the present study sought to analyze the events and investigate the impact of IMS on health and safety performance indices in an Iranian combined cycle power plants. Methods: This case study was conducted in 2012 in all units of the Yazd Combined Cycle Power Plant on accident victims before and after the implementation of IMS. For data analysis and prediction of indices after the implementation of IMS, descriptive statistics and Kolmogorov-Smirnov test, Chi-square, linear regression, and Cubic tests were conducted using SPSS software. Results: The number of people employed in the power plant in an 8-year period (2004-2011) was 1,189, and 287 cases of work-related accidents were recorded. The highest accident frequency rate and accident severity rate were in 2004 (32.65) and 2008 (209), respectively. Safe T-score reached to below -3 during 2010-2011. In addition, given the regression results, the relation between all predictor variables with outcomes was significant (p < 0.05), except for the variable $X^1$ belonging to the accident severity rate index. Conclusion: The implementation of safety programs especially that of IMS and its annual audits has had a significant impact on reducing accident indices and improving safety within the study period. Accordingly, health and safety management systems are appropriate tools for reducing accident rate, and the use of regression models and accident indices is also a suitable way for monitoring safety performance.

• Safety and Health at Work
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• v.9 no.4
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• pp.381-387
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• 2018

Background: Physician behaviors that undermine a culture of safety have gained increasing attention as health-care organizations strive to create a culture of safety and reduce medical errors. We developed, implemented, and assessed a course to teach physicians skills regarding effective coping and interpersonal communication skills and present our results regarding outcomes. Methods: We examined a professional development program specifically designed to address unprofessional or distressed behaviors of physicians, and we evaluated the impact on burnout, quality of life, and emotional flooding scores of the physicians. Assessments of burnout, quality of life, and emotional flooding were assessed preintervention and postintervention. Results: Results demonstrated statistically significant reductions over time in physicians' emotional flooding and emotional exhaustion (EE). Specifically, using a Wilcoxon Signed-Rank test, results revealed that flooding scores at follow-up were statistically significantly lower than at baseline, V = 590, p < 0.05, and EE and personal accomplishment distributions were found to significantly deviate from normal as indicated by Shapiroe-Wilks tests (p < 0.05). A Wilcoxon signed-rank test indicated that EE scores were significantly higher at baseline compared to follow-up 1, V = 285, p < 0.05. Conclusion: We conclude that the physician participants who enrolled in the educational skills training program improved scores on emotional flooding and EE and that this may be indicative of improved skills related to their experiences and learning in the program. These improved skills in physicians may have a positive impact on the overall culture of safety in the health system setting.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.211-220
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• 2019

In this study, three kinds of bainitic steel plates are manufactured by varying the chemical compositions and their microstructures are analyzed. Tensile and Charpy impact tests are performed at room and low temperature to investigate the correlation between microstructure and mechanical properties. In addition, heat affected zone (HAZ) specimens are fabricated by a simulation of welding processes, and the HAZ microstructure is analyzed. The base steel that has the lowest carbon equivalent has the highest volume fraction of acicular ferrite and the lowest volume fraction of secondary phases, so the strength is the lowest and the elongation is the highest. The Mo steel has a higher volume fraction of granular bainite and more secondary phases than the base steel, so the strength is high and the elongation is low. The CrNi steel has the highest volume fraction of the secondary phases, so the strength is the highest and elongation is the lowest. The tensile properties of the steels, namely, strength and elongation, have a linear correlation with the volume fraction of secondary phases. The Mo steel has the lowest Charpy impact energy at $-80^{\circ}C$ because of coarse granular bainite. In the Base-HAZ and Mo-HAZ specimens, the hardness increases as the volume fraction of martensite-austenite constituents increases. In the CrNi-HAZ specimen, however, hardness increases as the volume fraction of martensite and bainitic ferrite increases.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.129-135
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• 2021

Recently, additive manufacturing (AM) technology such as powder bed fusion (PBF) and directed energy deposition (DED) are actively attempted as consumers' needs for parts with complex shapes and expensive materials. In the present work, the effect of processing parameters on the mechanical properties of 316L stainless steel coupons fabricated by PBF and DED AM technology was investigated. Three major mechanical tests, including tension, impact, and fatigue, were performed on coupons extracted from the standard components at angles of 0, 45, 90 degrees for the build layers, and compared with those of investment casting and commercial wrought products. Austenitic 316L stainless steel additively manufactured have been well known to be generally stronger but highly vulnerable to impact and lack in elongation compared to casting and wrought materials. The process-induced pore density has been proved the most critical factor in determining the mechanical properties of AM-built metal parts. Therefore, it was strongly recommended to reduce those lack of fusion defects as much as possible by carefully control the energy density of the laser. For example, under the high energy density conditions, PBF-built parts showed 46% higher tensile strength but more than 75% lower impact strength than the wrought products. However, by optimizing the energy density of the laser of the metal AM system, it has been confirmed that it is possible to manufacture metal parts that can satisfy both strength and ductility, and thus it is expected to be actively applied in the field of electric power section soon.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.549-555
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• 2021

Open hole strength of composite laminates is often used as the design allowable strength for designing composite aircraft structures, particularly those structures subjected to impact loading. Generally, the degradation of strength due to a barely visible impact damage (BVID) is assumed as the strength of 6.0 mm hole diameter in 24.0 mm width specimen. In this study, the residual strength static tests of composite laminates containing circular holes have been performed to investigate the effects of fiber orientation structure on open hole strength. The point stress criterion using a characteristic length is used to predict the open hole strength. The finite element analysis has been used to validate the analytical method. From the test results, it is shown that the characteristic length is related to the percentage of 0°, ±45° and 90° plies of the laminate. And regression analysis has performed to determine the characteristic length and strength of no hole specimens on the arbitrary layup pattern.

• Journal of Periodontal and Implant Science
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• v.51 no.2
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• pp.124-134
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• 2021

Purpose: The aim of this study was to assess the association between the clinical status of rheumatoid arthritis (RA) and periodontitis (PD) in patients diagnosed with PD and to evaluate the impact of RA treatment on the severity of PD. Methods: The study included 148 participants with PD, of whom 64 were also diagnosed with RA (PD+RA group), while 84 age-matched participants were rheumatologically healthy (PD-only group). PD severity was assessed by the following periodontal parameters: clinical attachment loss, probing pocket depth (PPD), bleeding on probing (BOP), alveolar bone loss, and number of missing teeth. RA disease characteristics and impact of disease were evaluated by the Disease Activity Score 28 using C-reactive protein, disease duration, RA treatment, the RA Impact of Disease tool, and the Health Assessment Questionnaire. Outcome variables were compared using parametric and non-parametric tests and associations were evaluated using regression analysis with the calculation of odds ratios (ORs). Results: Participants in the PD+RA group had higher mean PPD values (2.81 ± 0.59 mm vs. 2.58 ± 0.49 mm, P=0.009) and number of missing teeth (6.27±4.79 vs. 3.93±4.08, P=0.001) than those in the PD-only group. A significant association was found between mean PPD and RA (OR, 2.22; 95% CI, 1.16-4.31; P=0.016). Within the PD+RA group, moderate to severe periodontal disease was significantly more prevalent among participants with higher RA disease activity (P=0.042). The use of biologic disease-modifying antirheumatic drugs (bDMARDs) was associated with a lower BOP percentage (P=0.016). Conclusions: In patients with PD, RA was associated with a higher mean PPD and number of missing teeth. The severity of PD was affected by the RA disease clinical activity and by treatment with bDMARDs, which were associated with a significantly lower mean BOP percentage.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.45-57
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• 2008

The improved turnout system is developed to speed-up the pre-existing railroad. The research has been actively carried out far the improved turnout system and the impact factor is estimated using the data sets achieved from the dynamic wheel-load field tests in both the conventional and the improved turnout system. In this study, the track performance and roadbed behavior are examined for the conventional and improved turnout system using the estimated impact factor. Dynamic wheel load and rail pressure are evaluated to assess the track performance. Roadbed stress and settlements are estimated using numerical analysis. Additionally, the stability of roadbed is estimated in soft roadbed condition influenced by the weather effects and cyclic train loading. The results show that dynamic wheel load, rail pressure, roadbed stress, and roadbed settlements in the improved turnout system substantially decrease compared with those in the conventional turnout system.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.377-390
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• 2022

The stability of the roof rock-coal pillar-floor rock composite structure is of great significance to coal mine safety production. The cracks existing in the composite structure seriously affect the stability of the roof rock-coal pillar-floor rock composite structure. The numerical simulation tests of rock-coal-rock composite structures with different crack characteristics were carried out to reveal the composite structures' mechanical properties and failure mechanisms. The test results show that the rock-coal-rock composite structure's peak stress and elastic modulus are directly proportional to the crack angle and inversely proportional to the crack length. The smaller the crack angle, the more branch cracks produced near the main control crack in the rock-coal-rock composite structure, and the larger the angle between the main control crack and the crack. The smaller the crack length, the larger the width of the crack zone. The impact energy index of the rock-coal-rock composite structure decreases first and then increases with the increase of crack length and increases with the increase of crack angle. The functional relationships between the different crack characteristics, peak stress, and impact energy index are determined based on the sensitivity analysis. The determination of the functional relationship can fully grasp the influence of the crack angle and the crack length on the peak stress and impact energy index of the coal-rock composite structure. The research results can provide a theoretical basis and guidance for preventing the instability and failure of the coal pillar-roof composite structure.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.206-213
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• 2024

This paper aims to investigate the causal relationship between geopolitical risk and stock price volatility in the shipping industry. Given its international nature and dependence on global trade, this industry is exposed to various uncertainties and risk factors. This study specifically focuses on the impact of geopolitical risk, which has gained significant attention in recent years due to events such as the Russia-Ukraine War and the Israel-Hamas War. To analyze this relationship, the study utilizes vector autoregressive model-based causality tests. The research estimates the causal relationship between geopolitical risk indicators and the stock price volatility of five shipping companies listed on the Korea Exchange. The study covers the period from 2000 to 2023. The results indicate the following: Firstly, an increase in geopolitical risk leads to a rise in stock price volatility for shipping companies. Moreover, the impact of actual geopolitical events, rather than just diplomatic disputes, is statistically significant. Lastly, the impact of geopolitical risk is particularly significant in the bulk shipping sector.