• Journal of the Korea Safety Management & Science
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• v.17 no.3
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• pp.115-123
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• 2015

The study conducted statistical analysis of survey on the 239 workers participating in national Tower Crane installation/dismantlement in order to identify work environment and health hazard exposure of Tower Crane workers. Consequently for work related safety status of Tower Crane workers, the number of installation/dismantlement work was the highest at 15-20 times per month, and safety equipments were not arranged at work and they felt highly anxious when boarding on the Tower Crane. Furthermore, it is found that they feel anxious working in the influence of the weather, noise, vibration, wind, the sun ray, and structure characteristic. They have very low satisfaction in the insecureness of workplace and the work environment, and recognizes that their work affect highly on the health. 81.6% of workers have experienced accident at work, the cause of accidents were mainly due to poor work environment, and the health abnormality they have experienced were mostly fatigue and concentration reduction. For job stress, job demand and conflict in relationship were the highest sections. Total 66.5% of workers complained of musculoskeletal disorder related subjective symptom, and back pain patients were the highest of all groups.

• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.347-359
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• 2021

This study aims to evaluate the dynamic responses of the jacket-type offshore wind turbine using FAST software (Fatigue, Aerodynamics, Structures, and Turbulence). A systematic series of simulation cases of a 5 MW jacket-type offshore wind turbine, including wind-only, wave-only, wind & wave load cases are conducted. The dynamic responses of the wind turbine structure are obtained, including the structure displacement, rotor speed, thrust force, nacelle acceleration, bending moment at the tower bottom, and shear force on the jacket leg. The calculated time-domain results are transformed to frequency domain results using FFT and the environmental load with more impact on each dynamic response is identified. It is confirmed that the dynamic displacements of the wind turbine are dominant in the wave frequency under the incident wave alone condition, and the rotor thrust, nacelle acceleration, and bending moment at the bottom of the tower exhibit high responses in the natural frequency band of the wind turbine. In the wind only condition, all responses except the vertical displacement of the wind turbine are dominant at three times the rotor rotation frequency (considering the number of blades) generated by the wind. In a combined external force with wind and waves, it was observed that the horizontal displacement is dominant by the wind load. Additionally, the bending moment on the tower base is highly affected by the wind. The shear force of the jacket leg is basically influenced by the wave loads, but it can be affected by both the wind and wave loads especially under the turbulent wind and irregular wave conditions.

• Journal of the Korean Institute of Gas
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• v.25 no.4
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• pp.1-9
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• 2021

The process and facilities of modern chemical plants are becoming increasingly complex, there is possibility of potential risk. Internal chemicals generate stress concentration when operated due to turbulence, laminar flow, pressure, temperature, friction, etc. It causes cumulative fatigue damage, which can damage or rupture chemical facilities and devices. The statistics of chemical accidents found that the highest rate of occurrence was in summer, and in the last five years statistics on chemical accidents, leakage incidents make up a decent percentage of accidents. Chemical leaks can cause serious human damage and economic damage, including explosions and environmental pollution. In this study, based on the leak accident of chemical plant, the risk analysis, and damage effects assessment were estimated using a 3D scanner and FLACS. As a result, if chemicals leak in summer, the risk is higher than in other seasons, the seasonal safety management measures, and countermeasure were estimated.

• Smart Structures and Systems
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• v.23 no.3
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• pp.263-278
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• 2019

Moving train load parameters, including train speed, axle spacing, gross train weight and axle weights, are identified based on strain-monitoring data. In this paper, according to influence line theory, the classic moving force identification method is enhanced to handle time-varying velocity of the train. First, the moments that the axles move through a set of fixed points are identified from a series of pulses extracted from the second derivative of the structural strain response. Subsequently, the train speed and axle spacing are identified. In addition, based on the fact that the integral area of the structural strain response is a constant under a unit force at a unit speed, the gross train weight can be obtained from the integral area of the measured strain response. Meanwhile, the corrected second derivative peak values, in which the effect of time-varying velocity is eliminated, are selected to distribute the gross train weight. Hence the axle weights could be identified. Afterwards, numerical simulations are employed to verify the proposed method and investigate the effect of the sampling frequency on the identification accuracy. Eventually, the method is verified using the real-time strain data of a continuous steel truss railway bridge. Results show that train speed, axle spacing and gross train weight can be accurately identified in the time domain. However, only the approximate values of the axle weights could be obtained with the updated method. The identified results can provide reliable reference for determining fatigue deterioration and predicting the remaining service life of railway bridges.

• Journal of Physiology & Pathology in Korean Medicine
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• v.34 no.6
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• pp.309-318
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• 2020

Besides respiratory infection, COVID-19 has many neurological symptoms not only loss of smell and taste but also fatigue and brain fog. But it is a challenge to treat the neurological symptoms especially of anosmia and ageusia. In order to search for the therapeutic methods, the geographical diversity and pathological mechanisms of the COVID-19 and two symptoms were investigated from the latest clinical studies. Because the environmental conditions of the monsoon climate zone of East Asia and the Mediterranean and Oceanic climate zone of Italy, Britain, United States and tropical Brazil are different, each of diverse etiology and internal milieu should be considered differently in the treatment. SARS-CoV-2 exhibits the dampness-like characteristics and the olfactory and gustatory disorders are particularly more common than other flu or cold. and it tends to show features of damaging the lung qi of olfaction and heart-spleen qi of gustation. The mechanisms of olfactory and gustatory loss are various according to precursory, inflammatory, non-inflammatory and sequelar forms, so the therapeutic method should be designed for each period and pathology. If the process of inflammation arises from nasal and respiratory, olfactory epithelium to the central nervous structure by way of blood brain barrier, the treatment should be corresponded with the stage and depth of pathogen place. And if the olfactory loss is asymptomatic or in the initial stage, it can be applied intranasal topical scent therapy to relieve temporary locking of qi movement, but maybe also used in parallel together with herbs of relieving dampness toxin latent in the lung parenchyma.

• Composites Research
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• v.22 no.1
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• pp.22-31
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• 2009

Recently the wind energy has been alternatively used as a renewable energy resource instead of the mostly used fossil fuel due to its lack and environmental issues. This work is to propose a structural design and analysis procedure for development of the 500W class small wind turbine system which will be applicable to relatively low speed region like Korea and for the domestic use. The wind turbine blade was performed structural analysis including stress, deformation, buckling, vibration and fatigue. In addition, the blade should be safe from the impact damage due to FOD(Foreign Object Damage) including the bird strike. MSC.Dytran was used in order to analyze the bird strike penomena on the blade, and the applied method Arbitrary Lagrangian-Eulerian was evaluated by comparison with the previous study results. Finally, the structural test was carried out and its test results were compared with the estimated results for evaluation of the designed structure.

• Women's Health Nursing
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• v.29 no.2
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• pp.91-103
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• 2023

Purpose: This study aimed to construct a structural equation model to explain and predict factors affecting the health-related quality of life (QoL) in female rheumatoid arthritis (RA) patients based on the health-related QoL model by Ferrans et al. (2005) and a literature review. Methods: Patients (N=243) who were either registered members of an internet cafe composed of patients with RA or rheumatology outpatients at two tertiary general hospitals in Busan, Korea, were recruited via convenience sampling. Data were collected from July 2 to September 9, 2021, and the survey was conducted using a web-based questionnaire. The data were analyzed by SPSS and AMOS 26.0. Results: The goodness-of-fit statistics of the final model exhibited good results (χ²/degree of freedom=2.68, Turker-Lewis index=.94, comparative fit index=.96, standardized root mean-squared residual=.04, root mean- square error of approximation=.08), and 11 out of 14 paths of the model were supported. The squared multiple correlation, which reflected the explanatory power of the environmental characteristics, symptoms, functional status, and perceived health status on health-related QoL, was 80%. In the hypothesis model, 10 paths had significant direct effects, 6 paths had significant indirect effects, and 12 paths had significant total (direct and indirect) effects. Conclusion: Considering that factors directly affecting the health-related QoL of female patients with RA were social support, symptoms (fatigue and depression), resilience, and perceived health status, and that resilience was the most influential factor, clinicians can encourage resilience. Hence, to improve the health-related QoL of female patients with RA, continuing management is necessary, using various intervention methods that focus on enhancing resilience from the early stage to the end of treatment for RA.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.45-55
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• 2008

The objective of this research was to develop a VEPCD (ViscoElastoPlastic Continuum Damage) Model which is used to predict the behavior of asphalt concrete under various loading and temperature conditions. This paper presents the VEPCD model formulated in a tension mode and its validation using four hot mix asphalt (HMA) mixtures: dense-graded HMA, SBS, CR-TB, and Terpolymer. Modelling approaches consist of two components: the ViscoElastic Continuum Damage (VECD) mechanics and the ViscoPlastic (VP) theory. The VECD model was to describe the time-dependent behavior of HMA with growing damage. The irrecoverable (whether time-dependent or independent) strain has been described by the VP model. Based on the strain decomposition principle, these two models are integrated to form the VEPCD model. For validating the VEPCD model, two types of laboratory tests were performed: 1) a constant crosshead strain rate tension test, 2) a fatigue test with randomly selected load levels and frequencies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.399-405
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• 2008

Development of the paved track is required as a low-maintenance of conventional line. The paved tracks are one of the types of the ballast reinforced tracks those are manufactured by adopting the prepacked concrete technique. The main elements of this tracks are large sleeper, low elastic pad, fastener, cement mortar, geotextile and recycled ballast. Low elastic pad is the most effective element of such tracks on the basis of stress-displacement characteristics, dynamic response and fatigue characteristics. The stiffness of the pad determine the stiffness of the track. Consequently, it is more important in case of concrete track structure such as paved track because application of low elastic pad seriously effect the durability and stability of the track. The main objective of this study is to confirm the reduction of train load, which transfer to roadbed through various pad effects. To achieve this task static, numerical analysis and real scale repeated loading test was performed while load reduction effect of low elastic pad was analyzed by using displacement, stress and strain ratio characteristics of the paved track.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.639-645
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• 2006

FRP (Fiber Reinforced Polymer) is an excellent new constructional material in resistibility to corrosion, high intensity, resistibility to fatigue, and plasticity. FBG (Fiber Bragg Grating) sensor is widely used at present as a smart sensor due to lots of advantages such as electric resistance, small-sized material, and high durability. However, with insufficiency of measuring displacement, FBG sensor is used only as a sensor measuring physical properties like strain or temperature. In this study, FRP and FBG sensors are to be hybridized, which could lead to the development of a smart FRP rod. Moreover, developing the estimated model for deflection with neural network method, with the data measured through FBG sensor, could make conquest of a disadvantage of FBG sensor - uniquely used for sensing strain. Artificial neural network is MLP (Multi-layer perceptron), trained within error rate of 0.001. Nonlinear object function and back-propagation algorithm is applied to training and this model is verified with the measured axial displacement through UTM and the estimated numerical values.