• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.76-85
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• 2012

Air traffic controllers often experience fatigue and stress on the job due to work-related factors. Performance impairment resulting from fatigue and stress is an important concern for aviation safety. The goal of this research was to investigate fatigue and stress factors for air traffic controllers. The research involved an extensive literature review of fatigue and stress in the air traffic control environment and surveyed fatigue and job stress level of Korean air traffic controllers compared to other occupation groups. Results of survey showed that fatigue and stress levels of air traffic controllers were significantly higher than other occupation groups. Specially air traffic controllers reported that night work created high level of fatigue and perceived that physical environment and job demand induced high level of stress. In addition, implications for fatigue and stress management were discussed.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.90-98
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• 2017

This paper is concerned with air traffic controllers' fatigue and stress that they experience during their daily job particularly as being shift workers. Previous researches reveal that the controllers' fatigue and stress increase by several factors including time spent at work, traffic intensity, visibility, etc. The researches also indicate that air traffic controllers' fatigue and stress can be reasonably surrogated by their heart rate. We set three hypotheses relating the influencing factors and the fatigue and stress represented by the heart rates. Using wrist bands, air traffic controllers' heart rates at various situations are collected at Choongju airport. The hypothetical tests explicitly confirm that the heart rate is highly correlated with the traffic level and the time spent at work. In particular, it be shown that even when handling the same traffic level, air traffic controllers' stress level increases as the time they spent at work increases.

• Plant Biotechnology Reports
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• v.4 no.3
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• pp.179-183
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• 2010

Ethylene is a key gaseous hormone that controls various physiological processes in plants including growth, senescence, fruit ripening, and responses to abiotic and biotic stresses. In spite of some of these positive effects, the gas usually inhibits plant growth. While chemical fertilizers help plants grow better by providing soil-limited nutrients such as nitrogen and phosphate, overusage often results in growth inhibition by soil contamination and subsequent stress responses in plants. Therefore, controlling ethylene production in plants becomes one of the attractive challenges to increase crop yields. Some soil bacteria among plant growth-promoting rhizobacteria (PGPRs) can stimulate plant growth even under stressful conditions by reducing ethylene levels in plants, hence the term "stress controllers" for these bacteria. Thus, manipulation of relevant genes or gene products might not only help clear polluted soil of contaminants but contribute to elevating the crop productivity. In this article, the beneficial soil bacteria and the mechanisms of reduced ethylene production in plants by stress controllers are discussed.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.558-567
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• 2017

This study was conducted to analyze the turnover intentions of railway traffic controllers among employees of a domestic railway corporation. Variables influencing job turnover intention included exploited variables (empowerment, job stress, job satisfaction, organizational commitment, exhaustion) that have been actively studied in other fields. The results showed that the empowerment of railway traffic controllers did not directly affect job stress and turnover intention, but had a direct effect on job satisfaction, organizational commitment, and exhaustion. Job stress did not directly affect job satisfaction, organizational commitment, and exhaustion, and job satisfaction did not directly affect organizational commitment, burnout, and turnover intentions. Burnout has a direct effect on turnover intention, indicating that exhaustion of railroad traffic controllers has an effect on turnover intentions. In conclusion, empowerment has a direct effect on burnout and exhaustion has a direct effect on turnover intention. This study suggests that management of empowerment and exhaustion is important for the prevention of turnover of railway traffic controllers.

• Smart Structures and Systems
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• v.8 no.4
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• pp.413-431
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• 2011

Under the external shearing stress, the external radial stress and the electric potential simultaneously, the piezoelectric hollow cylinder transducer is studied. With the Airy stress function method, the analytical solutions of this transducer are obtained based on the theory of piezo-elasticity. The solutions are compared with the finite element results of Ansys and a good agreement is found. Inherent properties of this piezoelectric cylinder transducer are presented and discussed. It is very helpful for the design of the bearing controllers.

• The Korean Journal of Air & Space Law and Policy
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• v.32 no.2
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• pp.67-100
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• 2017

Throughout the history of the aviation industry, from its origins in the $20^{th}$century to the present, accidents have always occurred. This paper deals with the legal liability of air traffic controllers, who represent one of the human factors causing these accidents. Though controller negligence turns out to be a main cause of the accident, Korea does not have additional judical case, since it was firstly declared that controller negligence was accountable for the air traffic accident in 1971. As such, we examine the liability of air traffic controllers as public officers. This paper looks not only at the role of air traffic controllers and pilots in accidents, but also at the applicability of controller liability in the context of Korean law. We determine that despite the high-stress environment, air traffic controllers must share in the responsibility to provide safe air navigation. Therefore, they cannot avoid legal liability.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.119-126
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• 2018

This study intended to exploratively testify human error causing factors for railway traffic controller, using AMOS structural equation model. Through literature survey, fatigue and stress as exogenous variable, errors in information process such as cognitive, memory, storage, and execution error as endogenous variable, and accident and incident(near-miss) as dependent variable were set up. Results based on AMOS using 201 railway traffic controllers' questionnaire showed that a clear causality loop like as 'stress ${\rightarrow}$ memory error ${\rightarrow}$ storage error ${\rightarrow}$ incident(near-miss) ${\rightarrow}$ accident' is formed. This result suggests that for the purpose of mitigation of traffic controller's accident, it is so necessary to reduce memory and execution error in the information processing process based on the effective management of stress, as the precedent of them.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.39-39
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• 2000

In this paper, a decoupler of tandem cold rolling mill is designed. Before designing the decoupler, this paper improved conventional linear model by considering friction and yield stress of rolling strip. In a stand, the decoupler let an output be controlled by an input. And even if states of other stands should be changed, current stand takes no interference from those changes. In addition, with the same method, a feedforward controller is designed for an input strip thickness error. Finally, performance of controllers above is shown with nonlinear simulation.

• Smart Structures and Systems
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• v.21 no.1
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• pp.99-111
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• 2018

Wind induced large bending oscillation amplitudes in tall and slender telecommunication steel towers may lead to precocious fatigue cracks and consequent risk of collapse of these structures, many of them installed in rural areas alongside highways and in highly populated urban areas. Varying stress amplitudes at hot spots may be attenuated by means of passive control mechanical devices installed in the tower. This paper gives an account of both mathematical-numerical model and the technique applied to design and evaluate the performance of a double controller installed in existing towers which is composed by a nonlinear pendulum and a novel type of passive controller described herein as a planar motion disk mounted on shear springs. Results of experimental measurements carried out on two slender tubular steel towers under wind action demonstrate the efficiency of the double controllers in attenuating the towers bending oscillation amplitudes and consequent stress amplitudes extending the towers fatigue life.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.1-5
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• 2009

In this research, structural analysis was conducted by applying ANSYS commercial code in order to evaluate deflection quantitatively when each weight of tension controllers was centered and weights and moments on a controller controlling tension amounts was varied in a machinery manufacturing flexible flat cable. Based on the numerical structure analysis, stress, strain and amounts of maximum deformation were obtained and investigated structural validity and was reflected on design of the controller.