• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.709-717
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• 2004

The diesel engine is often a serious excitation source in ships. Both the varying cylinder gas forces and the reciprocating and rotating mass forces associated with the crank and the connecting rod mechanism produce ample possibilities for excitation of the engine structure itself, the shafting, the surrounding substructures as well as the hull girder. This paper presents a guide for optimization of excitation forces produced by the marine propulsion 2-stroke diesel engine. The computational program for predicting the excitation forces is developed and applied to 2-stroke in-line engines. The object function is defined as the work done by every cylinder excitation force which is related to the mode shape of the diesel engine system, especially in the torsional vibration of the shafting. As a practical application of the presented method. the crank angle of 7 cylinder 2-stroke engine is optimized to reduce torsional vibration stresses on the shafting. Compared with the regular firing angle, about 60 ％ of the 4th order torsional vibratory stress on the propeller shaft can be reduced by optimizing the crank angle irregularly. The usefulness of the presented optimization method is confirmed by the measurements.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4041-4046
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• 2012

The recombinant expression of proteins has been the method of choice to meet the demands from proteomics and structural genomics studies. Despite its successful production of many heterologous proteins, Escherichia coli failed to produce many other proteins in their native forms. This may be related to the fact that the stresses resulting from the overproduction interfere with cellular processes. To better understand the physiological change during the overproduction phase, we profiled the metabolites along the time course of the recombinant protein expression. We identified 32 metabolites collected from different time points in the protein production phase. The stress induced by protein production can be characterized by (A) the increased usage of aspartic acid, choline, glycerol, and N-acetyllysine; and (B) the accumulation of adenosine, alanine, oxidized glutathione, glycine, N-acetylputrescine, and uracil. We envision that this work can be used to create a strategy for the production of usable proteins in large quantities.

• Korean Journal of Occupational Health Nursing
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• v.24 no.2
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• pp.76-85
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• 2015

Purpose: The purpose of this study was to identify knowledge structure of the Korean Journal of Occupational Health Nursing from 1991 to 2014. Methods: 400 articles between 1991 and 2014 were collected. 1,369 keywords as noun phrases were extracted from articles and standardized for analysis. Co-occurrence matrix was generated via a cosine similarity measure, then the network was analyzed and visualized using PFNet. Also NodeXL was applied to visualize intellectual interchanges among keywords. Results: According to the results of the content analysis and the cluster analysis of author keywords from the Korean Journal of Occupational Health Nursing articles, 7 most important research topics of the journal were 'Workers & Work-related Health Problem', 'Recognition & Preventive Health Behaviors', 'Health Promotion & Quality of Life', 'Occupational Health Nursing & Management', 'Clinical Nursing Environment', 'Caregivers and Social Support', and 'Job Satisfaction, Stress & Performance'. Newly emerging topics for 4-year period units were observed as research trends. Conclusion: Through this study, the knowledge structure of the Korean Journal of Occupational Health Nursing was identified. The network analysis of this study will be useful for identifying the knowledge structure as well as finding general view and current research trends. Furthermore, The results of this study could be utilized to seek the research direction in the Korean Journal of Occupational Health Nursing.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.6
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• pp.609-620
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• 2002

It is well known that during tensile testing, a part of the mechanical work done on the specimen is transformed into heat energy. However, the ultimate temperature rise and the rate of temperature rise is related to the nature of the material, conditions of the test and also to the deformation behaviour of the material during loading. The recent advances in infrared sensors and image/data processing techniques enable observation and quantitative analysis of the heat energy dissipated during such tensile tests. In this study, infrared imaging technique has been used to characterise the tensile deformation in AISI type 316 nuclear grade stainless steel. Apart from identifying the different stages during tensile deformation, the technique provided an accurate full-field temperature image by which the point and time of strain localization could be identified. The technique makes it possible to visualise the region of deformation and failure and also predict the exact region of fracture in advance. The effect of thermal gradients on plastic flow in the case of interrupted straining revealed that the interruption of strain and restraining at a lower strain rate not only delays the growth of the temperature gradient, but the temperature rise per unit strain decreases. The technique is a potential NDE tool that can be used for on-line detection of thermal gradients developed during extrusion and metal forming process which can be used for ensuring uniform distribution of plastic strain.

• Journal of Information Technology Services
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• v.20 no.5
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• pp.55-71
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• 2021

Technostress management is increasingly getting important as ICT advances and infiltrates every job and task. Especially with the advent of COVID-19, workers had to switch to teleworking utilizing ICT extensively. In this study, we developed a research model explaining antecedents and their impacts on technostress in telecommuting context, especially under the COVID-19 situation. The result revealed that techno-complexity, techno-invasion, and techno-overload are the dominant factors that affect the negative psychological responses in the COVID-19 situation. Among them, we found that techno-overload maintain the most significant influence. It is due to the lack of instant feedback on workload allocations in telework and the lack of adjustment period with the sudden shift to telecommuting. In the case of techno-complexity, employees seem to experience difficulty acquiring new technical skills. Finally, the techno-invasion came out significant, signifying the infiltration of working space by home-related activities. The emotion-focused coping strategy had a moderating effect. In contrast, the problem-focused coping strategy had no significant effect, indicating that an appropriate emotional coping strategy is more important for workers undergoing extreme changes in the work environment. Subsequently, practical and theoretical implications, limitations, and future research directions are discussed.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.511-525
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• 2021

In the design of underground excavation, the shear strength (SS) is a key characteristic. It describes the way the rock material resists the shear stress-induced deformations. In general, the measurement of the parameters related to rock shear strength is done through laboratory experiments, which are costly, damaging, and time-consuming. Add to this the difficulty of preparing core samples of acceptable quality, particularly in case of highly weathered and fractured rock. This study applies rock index test to the indirect measurement of the SS parameters of shale. For this aim, two efficient artificial intelligence methods, namely (1) adaptive neuro-fuzzy inference system (ANFIS) implemented by subtractive clustering method (SCM) and (2) support vector regression (SVR) optimized by Harmony Search (HS) algorithm, are proposed. Note that, it is the first work that predicts the SS parameters of shale through ANFIS-SCM and SVR-HS hybrid models. In modeling processes of ANFIS-SCM and SVR-HS, the results obtained from the rock index tests were set as inputs, while the SS parameters were set as outputs. By reviewing the obtained results, it was found that both ANFIS-SCM and SVR-HS models can provide acceptable predictions for interlocking and friction angle parameters, however, ANFIS-SCM showed a better generalization capability.

• Structural Engineering and Mechanics
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• v.82 no.6
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• pp.757-770
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• 2022

For the design of flexural and shear crack control for reinforced concrete (RC) beams related to serviceability and reparability ensuring, eight simply-supported normal-strength reinforced concrete (NSRC) beam specimens are tested and the existing high-strength reinforced concrete (HSRC) experimental data are included in the investigation of this work. According to the investigation results of flexural and shear cracks, this works modifies the existing design formulas to determine the spacing of the tensile reinforcement for the flexural crack control of a HSRC/NSRC beam design. Additionally, for a specified shear crack width of 0.4 mm, the allowable stresses of the shear reinforcement are also identified. For the serviceability and reparability ensuring of HSRC/NSRC beams, this works proposes the relationship curves between the maximum flexural width and allowable stress of the tensile reinforcement, and the relationship curves between the shear crack width and allowable shear force that can be used to do the crack width control directly.

• Journal of Korean society of Dental Hygiene
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• v.22 no.4
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• pp.259-272
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• 2022

Objectives: To identify the factors influencing the turnover intention of registered South Korean dental hygienists and analyze the effect sizes. Methods: Overall, 54 studies based on criteria of PICO from 1 January 2000 to 11 January 2022 were extracted. The factors related to turnover intention were applied to the ecological system theory and categorized. Subsequently, the effect size of the correlations was comprehensively meta-analyzed by dividing it into protective and risk factors depending on the negative or positive correlation direction. Results: For the overall effect size, the protective factor (ES_r=-0.458) was higher than the risk factor (ES_r=0.352). In the protective factors, organizational commitment and perceived organizational support belonging to the microsystem yielded the largest effect size. Furthermore, as for risk factors, burnout, job stress, work harassment, role conflict, and emotional labor belonging to the microsystem showed a moderate effect size. Conclusions: Factors belonging to the microsystem demonstrated a large effect size in both protection and risk factors for dental hygienists' turnover intention. Additionally, the factor showing the largest effect size was protective factor categorized into a microsystem.

• Safety and Health at Work
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• v.13 no.4
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• pp.448-455
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• 2022

Background: While the organizational factors that account for firefighters' burnout have been extensively explored, the individual factors related to how they regulate interpersonal conflicts and emotions remain to be investigated. Previous research has demonstrated the association between emotional intelligence and conflict management styles and burnout, but no study has looked at the interrelationships among these factors in high-risk sectors. The present exploratory study aimed to fill this research gap by investigating the relationships between conflict management style, emotional intelligence and burnout in a sample of firefighters. Methods: A cross-sectional study was conducted with 240 French firefighters. Measures comprised validated scales of conflict management styles, emotional intelligence and burnout. Results: Results showed that the integrating conflict style reduced burnout. They also revealed the effects of emotion regulation on burnout, whereby the awareness and management of one's own emotions reduced burnout. Moreover, awareness of one's own emotions moderated the relationship between integrating conflict resolution style and burnout, whereby the effect of integrating style on reduced burnout was higher when awareness of one's own emotions was high. Conclusion: These results reveal that strategies used by firefighters to regulate their emotions in order to meet the emotional demands specific to their job are important for reducing the emotional exhaustion component of burnout. Training programs for conflict and emotion management are needed to preserve the mental health of firefighters and ensure the safety of interventions.

• Journal of the Korea Safety Management & Science
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• v.26 no.2
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• pp.79-86
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• 2024

Scientific exploration of how occupational health risks relate with occupational illnesses are essential for mitigating health-related issues in industries. This study analyzed the risk scores obtained by occupational health risk assessments at 3,172 manufacturing companies and examined their effects on occupational illness. Statistical analyses revealed that companies with an occupational health manager (scored 89.1 out of 100) had significantly higher activity scores of health management compared to those without (78.2). However, companies with a history of occupational illness (79.1) or those classified as high-risk industries (85.2) had significantly lower activity scores than their counterparts (81.7, 87.3). In addition, regression analyses using factor analysis showed that latent risk factors such as cardiovascular disease/job stress, health management, and musculoskeletal problem significantly influenced the risk of occupational illness. The activity factors such as health management, work environment management, and regulatory complaisance significant impacted the reduction of occupational illness. The findings of this study can be used to improve the occupational health risk assessment method and utilized in effectively managing occupational risks in industries.