• 전기의세계
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• v.26 no.2
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• pp.99-103
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• 1977

The object of this work is to study an optimal design problem of the proportional load-frequency controller for the single-control area power system. The selfservice power station is still a popular means as a power supplying source on ships or in a certain manufacturing area. The power system of this kind can be formulated as a single control-area system and it attracts a certain academic interest in controlling the system frequency under disturbances. In this paper, the single control-area system is mathematically formulated as a linear, time-invariant system in state-space under certain assumptions. The optimal proportional control law and the realization of the controller in closed loop-version is studied so that the final system designed can attain the system frequency to the nominal stationing value after the small load-disturbance. As in general cases of optimal design problems, the performance index is assumed to be quadratic in states and the control effort, and the infinite time control process is assumed in this work. The final control system realized depicts certain improvements in case study; in stability, transient responses and in steady-state frequency deviation, even though the steady state error did not attain the zero value.

• Journal of Arbitration Studies
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• v.28 no.2
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• pp.179-200
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• 2018

The purpose of this study is to investigate the effects of service training and arbitration support on superstore workers' work performance. The conclusion could be summarized as follows. First, as a result of Hypothesis 1 that service training and arbitration support for superstore workers would significantly affect the factor of workers' emotional labor, when surface acting of emotion and frequency of expressing emotions were the dependent variable, only arbitration support was positively correlated. When emotional diversity was the dependent variable, there was a significantly positive relationship with service training. Second, for Hypothesis 2 that service training and arbitration support for superstore workers would significantly influence the workers' job satisfaction, it was found that only organizational support was significantly positive when wage satisfaction was the dependent variable. When job satisfaction was the dependent variable, service training and arbitration support were significantly correlated positively. Third, for Hypothesis 3 that service training and arbitration support for superstore workers would significantly affect the service delivery level when service responsiveness was the dependent variable, service training and arbitration support were significantly positive. When service expertise was the dependent variable, there was also a significantly positive relationship with service training and arbitration. On the other hand, all the three independent variables-service training, organizational support, and arbitration support-showed a significantly positive relationship when the willingness and effort of service was the dependent variable.

• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.73-93
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• 2012

With an active structural involvement in spiral case structure (SCS) that is always the design and research focus of hydroelectric power plant (HPP), the compressible membrane sandwiched between steel spiral case and surrounding reinforced concrete was often assumed to be linear elastic material in conventional design analysis of SCS. Unfortunately considerable previous studies have proved that the foam material serving as membrane exhibits essentially nonlinear mechanical behavior. In order to clarify the effect of membrane (foam) material's nonlinear stress-strain behavior on SCS, this work performed a case study on SCS with a compressible membrane using the ABAQUS code after a sound calibration of the employed constitutive model describing foam material. In view of the successful capture of fitted stress-strain curve of test by the FEM program, we recommend an application and dissemination of the simulation technique employed in this work for membrane material description to structural designers of SCS. Even more important, the case study argues that taking into account the nonlinear stress-strain response of membrane material in loading process is definitely essential. However, we hold it unnecessary to consider the membrane material's hysteresis and additionally, employment of nonlinear elastic model for membrane material description is adequate to the structural design of SCS. Understanding and accepting these concepts will help to analyze and predict the structural performance of SCS more accurately in design effort.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.12 no.19
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• pp.25-30
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• 1989

This study is concerned with a job sequencing method using the concept of sampling technique. This sampling technique has never been applied to develop the scheduling algorithms. The most job sequencing algorithms have been developed to determine the best or good solution under the special conditions. Thus, it is not only very difficult, but also taken too much time to develop the appropriate job schedules that satisfy the complex work conditions. The application areas of these algorithms are also very narrow. Under these circumstances it is very desirable to develop a simple job sequencing method which can produce the good solution with the short tine period under any complex work conditions. It is called a sampling job sequencing method in this study. This study is to examine the selection of the good job sequence of 1%-5% upper group by the sampling method. The result shows that there is the set of 0.5%-5% job sequence group which has to same amount of performance measure with the optimal job sequence in the case of experiment of 2/n/F/F max. This indicates that the sampling job sequencing method is a useful job sequencing method to find the optimal or good job sequence with a little effort and time consuming. The results of ANOVA show that the two factors, number of jobs and the range of processing time are the significant factors for determining the job sequence at $\alpha$=0.01. This study is extended to 3 machines to machines job shop problems further.

• Journal of Industrial Convergence
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• v.1 no.1
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• pp.159-169
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• 2003

In the 21st century, a time for smaller companies is fast approaching. A lot of people believe that the small and mid-sized companies will be a main force for industry. However, this concept could only be possible after we find some solutions for the general, labor shortage problem. Specifically, the majority of these challenges stem from improper distribution of labor within each company's divisions. These labor shortages have been influenced by a variety of exogenous (human) variables. The sources of the most serious problems come from the lack of appropriate labor and their fair wages. The work environment is also a contributing factor. These items are considered to be serious challenges to the development of smaller enterprises. The purpose of this study is to explore these difficulties. For solving the labor shortage, enterprises and government should offer employees supportive benefits. Enterprise companies should make an effort to improve their work environments. Companies should also use innovative strategies to raise labor compensation. With this in mind, smaller firms should struggle to retain their employees for an extended period of time and commit to an organizational business strategy. Governments should try to develop a higher recognition of smaller enterprises. They should create human power recruitment, development, and recourse policies as needed. Furthermore, they should manipulate existing policies to support human resource development that aids these companies to be more competitive with larger ones. Additionally, it is necessary to develop new, creative programs to help with the social recognition of smaller enterprises.

• The Korean Journal of Health Service Management
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• v.12 no.3
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• pp.95-106
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• 2018

Objectives: The purpose of this study was to analyze the recent research trends in health and mental health literacy and suggest their implications for future research. Methods: Ninety six articles on the topics of health literacy and mental health literacy that were published in journals in Korea during the last 10 years analyzed. Results: The majority of articles were published in medical journals, whereas the articles published in social and natural sciences journals were conducted by multidisciplinary research teams and seemed to be increasing generally. The participants studied in the selected articles were mostly older adults followed by adults aged 18 and over, and other various groups including health professionals and immigrant groups. More than 97% of the articles used quantitative research methods. Conclusions: Health literacy mirrors other health inequalities. To increase the level of understanding of health information, studies should be conducted using various variables. It is also necessary to develop a community education program that can be implemented in the community. Futher, the results highlighted the importance of interdisciplinary research. It is hoped that this effort will help solve t health inequality.

• Journal of Korean Biological Nursing Science
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• v.24 no.3
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• pp.141-149
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• 2022

Purpose: This study aimed to investigate the effects of grit and body composition on fatigue and burnout in shift-working nurses. Methods: A descriptive cross-sectional design using self-report questionnaires was employed. Data were collected between February and April 2021 from 192 shift-working nurses in 22 units of C tertiary hospitals. Of the 192, 175 nurses returned their completed questionnaires (return rate: 91.1%). The participants objectively measured their body composition for three consecutive days using a home body composition measurement scale. Results: Nurses with higher consistency of interest were more likely to have lower chronic fatigue (B = -5.23, p= .013), lower emotional exhaustion (B = -2.75, p< .001), and decreased depersonalization (B = -1.08, p= .014). Perseverance of effort was not statistically significant for fatigue; however, it was statistically significant for higher personal accomplishment among the subdomains of burnout (B= 2.50, p< .001). Skeletal muscle mass and body mass index had no significant effect on fatigue and burnout. Conclusion: To reduce fatigue and burnout in shift-working nurses, comprehensive efforts at the organizational and individual levels should be implemented to increase their grit. Further research is needed to determine whether body composition affects fatigue and burnout in shift-working nurses.

• Korean Journal of Exercise Nutrition
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• v.23 no.1
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• pp.55-62
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• 2019

[Purpose] The effect of acute nitrate supplementation on muscle fatigue is largely unknown. This study aimed to evaluate the effect of acute nitrate supplementation on muscle fatigue. [Methods] Thirty-five recreationally active subjects consumed 140 ml of beetroot (BR) juice (nitrate: 8 mmol·d^-1) or placebo (PL) 12 and 2.5 hours before two exercise sessions. Peak torque was measured during 50 repetitions, at maximal effort, and during concentric knee extensions at 90°·s^-1. Blood pressure (BP) was recorded pre- and post-exercise. [Results] Peak torque, maximum work, rate of fatigue, and rate of work fatigue were similar between the BR and PL conditions. Post-exercise diastolic BP (BR: 67.2 ± 9.8 vs. PL: 64.5 ± 7.9 mmHg, p < 0.05) and mean arterial pressure (BR: 91.6 ± 9.3 vs. PL: 88.8 ± 8.2 mmHg, p < 0.05) were higher with BR supplementation. [Conclusion] These findings suggest that the acute intake of BR juice had no effect on knee extensor muscle strength or fatigue but increased BP in a healthy recreationally active population.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.74-79
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• 2013

Aiming at reducing deaths and injuries involving construction crane operations, OSHA has recently updated its 40-year-old crane safety standards with new rules addressing the use of cranes and derricks in construction. The goal of this change in rule is to deal with the leading causes of fatalities related to crane and derrick operations. Employers in the construction industry are mandated to ensure that employees in the work zone are trained to recognize hazards associated with the use of the equipment and any related duties that they are assigned to perform. However, those responsible at construction sites for the supervision and management of safe crane operations often lack the integrated knowledge of the standards, regulations and best practices for conducting or supervising daily, monthly, or quarterly inspection of cranes. As such, proper planning, management and implementation of crane operations, including inspections are just as paramount to reducing accidents on the construction site. It is important that engineers responsible for the management and planning of crane operations understand the latest OSHA crane and hoisting standards to ensure a safer work environment is maintained. Many on site engineers overseeing crane operations do not have adequate training, experience, and knowledge of the inspection requirements to assess safe crane operation and too often rely on the crane operator's judgement. This paper highlights recent research effort in defining significant changes in new crane and hoisting standards and provides basis for safety construction operations.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.1-6
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• 2013

Concrete construction requires utilization of many temporary facilities such as formwork, shoring, and scaffolding. Appropriate use of these temporary facilities greatly impacts the quality, cost, schedule, and safety of concrete construction. The current practice in design and planning of temporary facilities is often manual, error-prone, and re-active based on construction site layout, status, and progress in the field. Early design and planning of temporary facilities for concrete construction using Building Information Modeling (BIM) technology offers a potential solution. Although some commercially-available software exists that assists in the generation of temporary facility designs, the construction industry lacks tools that support detailed planning and design of many other temporary facilities. This research presents our early work in automating the design and planning of temporary facilities utilizing BIM. Algorithms were developed to automatically assess geometric conditions of work space to detect required temporary facilities and design them. The proposed methodology was implemented in a test model. By automatically incorporating temporary facilities into BIM, more realistic construction models can be created with less effort and errors. Temporary facilities-loaded models can finally be used for communication, bill of materials, scheduling, etc. and as a benchmark for field installation of temporary formwork, shoring, and scaffolding systems.