• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.318-323
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• 2024

In this paper, computer modeling works have been performed for the power generation Rankine cycle using new working fluids and liquefied natural gas (LNG) cold heat. PRO/II with PROVISION released January 2023 from AVEVA company was used, and Peng-Robinson equation of the state model with Twu's alpha function was selected for the modeling of the power generation cycle. Optimal working fluid composition was determined to maximize LNG cold heat to increase power generation efficiency and net power production.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.358-363
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• 2015

As a preparation process for successful establishment of demonstration offshore wind farm, analyses have been made for working time at the construction site where working time is defined as the time available for marine operation to take place under given weather conditions. Data used are hourly wave and wind data from met mast, HeMOSU-1, and 3 hour numerical model data from Korea Meteorological Administration (KMA). Seasonal results show the minimum working time during winter and moderate during autumn and spring. The most working time was seen during summer on average. Monthly analyses show the most working time in May, June, and August which was higher than the working time in July and September. Working time reaches at steady state and no significant change was seen above wave height of 1.5 m and wind speed of 8 m/s.

• Safety and Health at Work
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• v.12 no.3
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• pp.324-338
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• 2021

Background: We hypothesized that the growing demand of Korean workers for work-life balance would change the factors influencing job satisfaction. We sought to verify our hypothesis by conducting a conjoint analysis based on the Korean Working Conditions Survey (KWCS). Methods: We analyzed the raw data of the KWCS, conducted by the Occupational Safety and Health Research Institute from 2006 to 2017. To complete the analysis, we counted on a conjoint model of analysis, typically used in the analysis of customer satisfaction. The dependent variable was the satisfaction of workers with their working conditions, and the independent variables were the job quality indicators identified by Eurofound. Results: The factors that have the greatest impact on working conditions satisfaction are summarized as follows: "physical environment" for the first wave, "adverse social behavior" for the second wave, "occupational status" for the third and fourth waves, and "management quality" for the fifth wave. "Earnings" were not a major factor in determining employee job satisfaction, and the relative importance index is decreasing. Conclusion: According to the results of the analysis of the tendencies of Korean workers, the factors that affect the satisfaction with the working conditions have changed over time. It is crucial to identify factors that affect working conditions to assure the health and productivity of workers. The results of this study demonstrate that policymakers and employers are required to attentively consider human relations and social environment at work to improve working conditions in the future.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.44.1-44.12
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• 2022

Background: Recently, use of work-related communication technology-smartphones, tablets, and laptops-is increasing rapidly by development of technology with the coronavirus disease 2019 pandemic. Some studies have suggested that work-related communication technology has a significant link with work-family conflict (WFC) but these studies included only limited number of participants and lacked essential covariates. Therefore, this study analyzes this association using large representative data sample and selected waged workers who were married-couples with children. Methods: This study was conducted based on data from the 6th Korean Working Conditions Surveys (KWCS). A total of 17,426 waged workers having a marriage partner and one or more children were selected. Logistic regression analysis was performed to determine whether WFC was associated with communication technology use. The odds ratios (ORs) for WFC were stratified by sex and working hours. Results: In fully adjusted model, WFC was higher those who used communication technology outside regular working hours compared with those who did not use it (OR: 1.66; 95% confidence interval [CI]: 1.39-1.97). When stratified by sex and working hours, the effect was greater in women than in men (OR: 1.79; 95% CI: 1.42-2.26 vs. OR: 1.52; 95% CI: 1.17-1.97) and women who worked over 52 hours per week had the highest OR (3.40; 95% CI: 1.25-9.26). Conclusions: This study revealed that the work-related communication technology use outside regular working hours was associated with WFC. The association were greater among those having longer working hours and female workers. These results suggest that appropriate policy should be implemented to reduce working hours and right to disconnect after work, particularly in female workers.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.177-183
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• 2012

Objectives: The objectives of this study are to discuss the importance of job stress and to introduce a model of job stress at the shipbuilding industry considering the characteristics of the shipbuilding works. Background: Shipbuilding works consist of grinding, painting, interior works, welding, and assembling and using heavy equipment in narrow space or work at outside or at high and dangerous places. The working environments aggravate the stress to the workers. Methods: Studies of job stress in industries including shipbuilding industries were reviewed and the characteristics of jobs of shipbuilding were analyzed to find causes of job stress. Results: A model was constructed based upon these findings and reviews. Conclusions: Job stress of shipbuilding workers are very high and thus job and working conditions need to be improved to attenuate the level of job stress of shipbuilding workers. Applications: This model can be used to identify the highly stressed workers and sources of stress.

• Journal of KSNVE
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• v.9 no.4
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• pp.754-760
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• 1999

The valve motions of a reciprocating compressor generate the pressure fluctuation at the plenum which is a main source of noise and vibration of a compressor unit. But a cycle of a compressor process consists of complicated phenomena interacting in a short period of time. A mathematical model is developed by simplifying and idealizing the complicated phenomena to simulate the compressor process. The governing equations about the pressure and working fluid flow are developed from the unsteady Bernoulli equation. The pressure fluctuations at the plenums are derived from the Helmholz's resonator model. The valves are modeled as one degree of freedom spring-mass-damper system. This model is verified by the experimental results.

• Journal of the Korean Institute of Rural Architecture
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• v.7 no.2
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• pp.1-8
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• 2005

In a rural house, it is necessary to make a quality model that choose effective design value engineering. So more effective models, this study examine requests of a rural house project designers, constructors, and tenants. Checked items are classified into four groups that working area, dwelling area, constructive and environmental parts. Each groups are also divided into detailed items for basic decisional elements. When basis points sets 10, it can be divided that working area parts 3pts, dwelling area parts 2.5pts, constructive parts 3pts and environmental parts 1.5pts. In this results, we can make a proposal of evaluation on additive value quality model for a rural house in design value engineering.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.335-337
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• 2009

A scanning electron microscope(SEM) is a system that visualizes complex surface features. The resolution of SEM is affected by each of equipment components. In this study, we examined the effects of the four factors including the beam current, magnification, voltage and working distance. A statistical analysis was conducted to investigate the main and interaction effects. For a systematic characterization, a $2^4$ full factorial experiment was conducted. The $R^2$ of constructed statistical model was 88.9%. The main effect revealed that the current and working distance are dominant factors. Of the interactions, those between the current and voltage yielded the highest interaction. 3D plots generated from the model were used to explore various parameter effects.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.276-278
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• 1999

In this paper, we analyze customers' working electric energy (kWh) which is served pole-transformer in order to reduce peak load current error which is generated in application load correlation equation. The characteristic of electric load which customers are using is classified by customer's working electric energy (kWh) and ratio of cooling equipment possession. For the input data of fuzzy model, we used to kWh on April which represents basic load and kWh which is increased from April to August. The April kWh is used to classify into large, medium, small customer. Also, the increased kWh is used to know information of cooling equipment possession. For the output value of fuzzy model, we can determined peak load current limit in application load correlation equation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.687-689
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• 2014

This paper deals with the optimal muffler model by using acoustic analysis and CFD(computational fluid dynamics) analysis. The complicated muffler model could be better noise reduction performance. However, it could be worse affected to back-pressure performance by pressure drop in working fluid. High back-pressure is caused to low system efficiency. Therefore, it is important for the muffler design to consider the pressure drop. The muffler models are changed their partition plate position. Acoustic power transmission loss(TL) and pressure drop of working fluid are calculated by using computational analysis and used to build database for finding their trends. The optimal muffler model in user-interested frequency range could be selected by analyzing this database.