• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.1-10
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• 2022

The purposes of this study were to suggest 1) a future direction for Korea's machine tool industry and 2) how to secure the safety and reliability of emerging intelligent or automated machine tooling. The study concludes that, overseas, the machine tool industry is growing again while promoting innovation by converging with ICT. Accordingly, Korea also promotes ICT innovation to advance the machine tool industry, which is at the core of the national economy. As a result, unlike in the past, the frequency of serious injuries like entrapment accidents has recently decreased, while the proportion of collision accidents has increased. In addition, a new type of accident has become possible. Since ICT is network-based, the distinction between work and rest can become ambiguous; there is a risk of hacking, working hours and places are flexible and there are risk factors for diseases like chronic fatigue due to overload of specific personnel. As robots and automation are introduced, there is also a high probability of problems caused by physical and psychological burdens on system operators and resulting fatigue.

• Journal of Distribution Science
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• v.19 no.12
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• pp.91-101
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• 2021

Purpose: This study aims to explore the effects of government's value intervention messages on the prevention and control of infectious disease in the risk communication process in terms of goveremnt policy response to COVID-19 from the mismatch message perspective, and draws the relevant implicaitons. Due to the infeciton spread, some people point out that depression caused by COVID-19 is because of wrong signals of the government and infectious disease prevention and control authorities, namely value intervention messsages. Research design, data and methodology: This study examined the epidcmic situation through message deails regarding the effects of government's mismatch messages on prevention and control of infectious disease and the resulting phenomena. Results: People's lives are under serious threat overall, so the declaration of the end of COVID-19 is almost impossible unlike MERS. Economic downturn due to foreced prevention and control regulaitons of COVID-19, mistruct of social distancing, fatigue on mismatch messages, and moral hazard on the awareness of prevention and control of infectious disease are negative phenomena to risk communiaiton on COVID-19. Conclusions: This study investigated the government authorities' policy sending wrong signals due to mismatching of the reality at this point in time for infectious disease prevention and control from the risk communicaiton perspectrive.

• Korean Journal of Psychosomatic Medicine
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• v.22 no.1
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• pp.3-12
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• 2014

Objectives : We aimed to explore the relationship among fatigue and perceived stress, depressive mood in the working population. We also examined associations with demographic and life style factors and investigated the effect of individual coping skills on these associations. Methods : Fatigue Severity Scale(FSS), Perceived Stress Scale(PSS), Brief Encounter Psychosocial Instrument - Korean version(BEPSI-K), Beck Depression Inventory(BDI), Stress Coping Skill Questionnaire were administered to 621 civil servants. All of above and other demographic factors are self-administered questionnaire survey and this study is cross sectional. Results : Mean FSS score was 3.04 which was lower than 3.22, the severity cut off score. FSS, PSS, BEPSI-K, BDI were all higher in female. Subjects with active coping skills showed relatively low fatigue, perceived stress, depressive mood than those with passive coping skills. Logistic regression analyses indicated that the PSS, BDI, BEPSI-K in working population increase the risk of fatigue and regular exercise lowers the risk. Conclusions : Adults who were afflicted by stress, experienced depressive mood or were physically inactive were at much higher risk of feeling fatigue. Since no other large data sets are available for fatigue, the results from this study could serve a very useful purpose, to furnish a basis for comparison with future research results based on more complete data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.77-83
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• 2019

Upon installing a seismic isolation device on a nuclear power plant, the device takes on the suppression of seismic loads. This is expected to bring about a larger displacement than what is seen prior to the installation of the seismic isolation device. Depending on the displacement change, the seismic risk for some equipment can increase. Particularly in case of the piping system, which is used for connecting the structure isolated from seismic events with common structures, the seismic risk is expected to rise significantly. In this study, the limit state of the steel pipe tee, which is a vulnerability part of the nuclear power plant piping system, was defined as leakage, and an in-plane cyclic loading test was conducted. As it is difficult to measure the moment and rotation of the steel pipe tee using the conventional sensors, an image signal was used. This study proposed a leakage line and low-cycle fatigue curves using the relationship between the moment and the rotation of a 3-inch steel pipe tee.

• Journal of Korean Dental Science
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• v.15 no.2
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• pp.112-120
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• 2022

In this article, the contemporary root canal treatment procedure using nickel-titanium (NiTi) instruments was reviewed to understand the correlations between the properties of files and safety of the clinical usage. Literatures were reviewed according to the process of clinical procedure of the root canal preparation, mainly for shaping during orifice flaring, glide-path preparation, and main canal instrumentation. Considering the reasons for NiTi file fracture, clinically implacable issues and ideas were discussed to reduce the fracture risk and increase clinical efficiency of the NiTi file systems. Various kinds of NiTi file systems have their own characteristics and properties given from their geometries and heat treatments and so on. Proper selection and careful usage of the NiTi file systems may reduce the risk of file fracture and increase the efficiency of NiTi file systems. Understanding of the clinical implications from the mechanical properties and characteristics of the engine driven NiTi instruments may decrease the risk of NiTi file fractures and increase the success rate in root canal treatment.

• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.723-730
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• 2008

Due to the higher ratio of live load to total loads of railway bridges, the accumulated damage by cyclic fatigue is significant. Moreover, it is highly possible that the initiated crack grows faster than that of highway bridges. Therefore, it is strongly needed to assess the safety for the accumulated damage analytically. The initiation and growth of fatigue-crack are related with the stress range, number of cycles, and the stiffness of the structural system. The stiffness of the structural system includes uncertainties of the planning, design, construction and maintenance, which varies as time goes. In this study, the authors developed the design and risk assessment techniques based on the reliability theories considering the uncertainties in load and resistance. For the probabilistic risk assessment of crack growth and the remaining life of the structures by the cyclic load of railway and subway bridges, response surface method (RSM) combined with first order second moment method were used. For composing limit state function, the stress range, stress intensity factor and the remaining life were selected as input important random variables to the RSM program. The probabilities of failure and the reliability indices of fatigue life for the considered specimen under cyclic loads were evaluated and discussed.

• Journal of Preventive Medicine and Public Health
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• v.38 no.1
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• pp.45-52
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• 2005

Objectives : To investigate the fatigue subjective symptoms and VDT related risk factors in bank workers. Methods : A total of 2178 workers (62.8% male, 37.2% female) were surveyed with a self-administered and structured questionnaire consisting of 30 fatigue symptoms and other VDT related factors regarding work characteristics, work postures, work environments, personal medical histories, etc. Fatigue subjective symptoms were divided into 3 groups of 10 questions each: a dull, drowsy and exhausted feeling (Group I), a mental decline of working motivation (Group II), or a feeling of incongruity in the body and dysfunction of autonomic nervous system (Group III). Each question was weighted as 0 for 'none', 1 for 'sometimes', and 2 for 'always'. Results : Mean age was $35.8{\pm}7.2$ years ($38.9{\pm}6.0$ in males, $30.6{\pm}5.8$ in females), Mean work duration was $7.7{\pm}7.1$ years ($8.4{\pm}7.4$ in males, $6.5{\pm}6.4$ in females). Mean symptom score in males was $11.0{\pm}8.1$ ($4.9{\pm}3.1$ in Group I, $3.0{\pm}3.1$ in Group II, $3.1{\pm}2.8$ in Group III) and in females was $17.5{\pm}9.5$ ($7.0{\pm}3.8$ in Group I, $4.6{\pm}3.5$ in Group II, $5.9{\pm}3.4$ in Group III). Mean scores were higher in the order of Group I>III>II. Females had significantly higher scores than males in all three groups (p<0.001). Most common symptoms complained of as 'always' or 'sometimes' were feel strained in the eyes' (85.4%) among Group I, 'find difficulty in thinking'(54.2%) among Group II, and 'feel stiff in the shoulders (72.3%) among Group III. In multiple regression analysis, female, non-straight spine at workstation, more VDT work hours, history of physical therapy, glare of screen, overtime work, young age, and non-horizontal elbow position were significantly related with high score of symptoms. Conclusions : More supportive VDT work environment and education for correct work postures for VDT workers are recommended.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.38-44
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• 2018

Military aircraft may have fatigue cracks in structurally weak areas due to multiple factors such as the accumulation of flight time while perform various missions and unpredictable air conditions. As a fatigue crack progresses, there is a risk that the structure will be destroyed in extreme cases, which can have a significant impact on flight safety. In this study, a cracking phenomenon was observed during the periodic inspection the inner support of the fairing, which is installed to protect the connection between the wing and the body of the aircraft. Therefore, a study on a series of quality improvement processes for reformation was described. In order to identify the causes of cracks, pre-load generation occurrence during the wing assembly process was investigated and a fracture analysis was performed. Also, the design of the support structure was suggested in terms of preventing recurrence of cracks. The structural integrity was verified using a stress and fatigue life analysis.

• Physical Therapy Rehabilitation Science
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• v.6 no.3
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• pp.140-145
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• 2017

Objective: The purpose of this study was to investigate the effect of visual block with ankle joint fatigue on gait and dynamic balance ability. Design: Cross-sectional study. Methods: Thirty healthy young adults (men=15, women=15) between 22 to 25 years of age voluntarily participated in this study. All subjects performed the gait and dynamic balance test successively in two conditions: the visual block and the open eyes condition. Before the gait and dynamic balance test, muscle fatigue on the ankle joint was induced to all subjects by doing ankle dorsiflexion and plantarflexion alternately, and then gait parameters (step length, stride length, cadence, velocity, single limb support, and double limb support) were assessed by walking on the GAITRite system (CIR Systems Inc., USA). Subjects also performed the functional reach test (FRT) for assessment of dynamic balance. This study examined gait parameters and FRT scores in each visual block and open eyes condition. Results: The results showed that FRT scores with the visual block condition significantly decreased compared to without visual blocking (p<0.01). Step length, stride length, cadence, and velocity of gait parameters decreased significantly in the visual block condition (p<0.01) while there was no significant difference for single limb support. However, double limb support increased significantly in the visual block system (p<0.01). Conclusions: Therefore, blocking of visual information with muscle fatigue of the ankle joint can affect gait and balance ability of young adults and increase the risk of falls.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.13 no.2
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• pp.12-20
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• 2007

The purpose of this study was designed to find out the effectiveness of vertebral segment instability, muscle fatigue response on lumbar spine after apply lumbosacral stabilization exercise program to 4 patients with chronic low back pain and for 12 weeks. In this study, the lumbar spine motion with blind by MedX test machine and the difference of instability to lumbar vertebra segments in flexion, extension test of standing position and spinal load test(Matthiass Test) by Spinal Mouse. The stabilization exercise program was applied 2 times a week for 12 weeks in hospital and 2 times a day for 20 minutes at home. The results of the present study were as follows: 1. Instability test of lumbar vertebra segment is 2 type differential angle test between vertebrae segment and loading test of spine(matthiass) by Spinal Mouse. It appeared to improve stability of segments in sagittal plane after applying program. So lumbar spine curve increased lordosis toward anterior and was improved of the lumbar spine flexibility in flexion and extension. Specially, in matthiass test, (-) value was increased between lumbar vertebra segment when was the load on spine. And so applying stability improved after program. 2. Fatigue response test(FRT) results, in male, was raised muscle fatigue rate during increase weight, on the other hand female appeared lower than male. As a results, lumbosacral stabilization exercise was aided to improvement of lumbar spine vertebra segments stabilization. Spine instability patients will have a risk when in lifting a load or working with slight flexion posture during the daily of living life and it is probably to increase recurrence rate. Thus, not only lumbar extension muscle strength but also stability of vertebra segments in lumbar spine may be very important.