• Title/Summary/Keyword: Degree of Fatigue

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Fatigue Strength of In-plane Welded Attachments (면내 거셋 용접연결부의 피로강도)

  • Bae, Doobyong
    • Journal of Korean Society of Steel Construction
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    • v.15 no.6 s.67
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    • pp.629-637
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    • 2003
  • This s paper presented the results of the three phases of fatigue tests to determine the fatigue strength of in-plane welded gusset joints, which are the most common details inevitably existing in the region of high stress range. A total of 57 fatigue specimens with varying thickness and strengths were made and tensile fatigue tests performed. One full-scale beam fatigue test was also performed. The validity of the fatigue strength of those details in the specification was confirmed, with the effects of thickness of flanges and welded attachments, length of attachments, and strength of applied steel examined. The characteristics of crack initiation and propagation were also observed. The test result was evaluated by comparing it with other test data and fatigue criteria of other countries. To determine the degree of stress concentration in the weld toe depending on geometric configuration such as attachment length and transition radius, analyses were performed. Compared to the present specification, analytical results indicate the need to revise and subdivide the detail categories.

The Study on Respiratory Function, Spirometric Lung Pattern and Fatigue of Elderly in a Facility

  • Shin, Hee Joon;Kim, Ji Sung;Wang, Joong San;Choi, Yoo Rim;Kim, Hong Rae;Park, Si Eun;An, Ho Jung;Min, Kyung Ok
    • Journal of International Academy of Physical Therapy Research
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    • v.4 no.1
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    • pp.488-493
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    • 2013
  • The purpose of this study was to investigate spirometric lung pattern, respiratory function and degree of fatigue by lung function tests and fatigue tests of 39 elderly people in a care facility aged 65 and over. The respiratory function tests were used to the Spirovit SP-1 and fatigue tests were used modified Piper fatigue scale(mPFS). Regarding the respiratory function, the FVC was $1.41{\pm}0.36$l, the FVC % predicted was $69.10{\pm}14.98$%, the $FEV_1$ was $1.02{\pm}0.31$l, the $FEV_1$ % predicted was $63.27{\pm}16.05$%, the $FEV_1$/FVC was $72.77{\pm}13.40$%, and the fatigue score was $5.83{\pm}1.09$. As for the spirometric lung pattern, 19 patients had a restrictive pattern(48.7%), followed by 11 with a mixed pattern(28.2%), 5 with an obstructive pattern( 12.8%), and 4 with a normal pattern(10.3%). Regarding the respiratory function and fatigue by spirometric lung pattern, the FVC and the FVC % predicted of patients with a normal pattern or an obstructive pattern were greater than other groups at a statistically significant level. As for the $FEV_1$, that of patients with a normal pattern was significantly higher than others, and for the $FEV_1$ % predicted, that of patients with a normal pattern or a restrictive pattern was significantly higher(p<.001). Fatigue score by patients with a normal pattern was significantly less than patients of other patterns(p<.001). Therefore, pulmonary physical therapy is considered necessary to improve respiratory function and fatigue degradation of elderly in a facility.

Clustering Analysis on Heart Rate Variation in Daytime Work

  • Hayashida, Yukuo;Kidou, Keiko;Mishima, Nobuo;Kitagawa, Keiko;Yoo, Jaesoo;Park, SunGyu;Oh, Yong-sun
    • Proceedings of the Korea Contents Association Conference
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    • 2017.05a
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    • pp.257-258
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    • 2017
  • Modern society tends to bring excessive labor to people and, therefore, further health management is required. In this paper, by using the clustering technique, one of machine learning methods, we try to bring out the measure of fatigue from heart rate (HR) variation during daytime work, helping people to get high-quality of healthy and calm life.

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Job Satisfaction Improvement Ways of Fire Official - With a Focus on First-aid Staff - (소방공무원의 직무만족도 향상방안 - 구급대원을 중심으로 -)

  • Kong, Ha-Sung;Lee, Woo-Seoung;Woo, Seong-Cheon
    • Fire Science and Engineering
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    • v.21 no.1 s.65
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    • pp.19-28
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    • 2007
  • The result of survey on job satisfaction of first-aid staff found that degree of work-related stress of 119 first-aid staff got total average 2.54 point (SD.44) out of 4. The degree of fatigue that first-aid staff feel got 2.09 point (SD.49) out of 4. The degree of job satisfaction of 119 first-aid staff got 2.71 point out of 5. This study suggests increasing of new hire, continuous education through teaching before employment, studying abroad, and so on, expansion and modernization of first-aid equipment, introduction and management of OAT institution for improvement of job satisfaction of first-aid staff.

Lifetime seismic performance assessment of high-rise steel-concrete composite frame with buckling-restrained braces under wind-induced fatigue

  • Liu, Yang;Li, Hong-Nan;Li, Chao;Dong, Tian-Ze
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.197-215
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    • 2021
  • Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

Prediction Model of Fatigue in Women with Rheumatoid Arthritis (여성 류마티스 관절염 환자의 피로 예측 모형)

  • Lee, Kyung-Sook;Lee, Eun-Ok
    • Journal of muscle and joint health
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    • v.8 no.1
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    • pp.27-50
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    • 2001
  • Rheumatoid arthritis is a chronic systemic autoimmune disease. Although the joints are the major loci of the disease activity, fatigue is a common extraarticular symptom that exists in all gradations of rheumatoid arthritis. Fatigue is defined as a subjective sense of generalized tiredness or exhaustion and has multiple dimensions. Therefore fatigue is a common and frequent problem for those with rheumatoid arthritis. In fact, 88-100% of individuals with rheumatoid arthritis experience fatigue. Especially the degree of fatigue is higher in women than men with rheumatoid arthritis. Despite the importance of fatigue among the patients with rheumatoid arthritis, the mechanism that leads to fatigue in rheumatoid arthritis is not completely understood. This study was intended to test and validate a model to predict fatigue in women with rheumatoid arthritis. Especially it was intended to identify the direct and indirect effects of the variables of pain, disability, depression, sleep disturbance, morning stiffness, and symptom duration to fatigue. Data were collected by questionnaires including Multidimensional Assesment of Fatigue(Tack, 1991), numeric scale of pain, graphic scale of joints, Ritchie Articular Index, Korean Health Assessment Questionnaire(Bae, et al., 1998), Inventory of Function Status(Tulman, et al., 1991), Center for Epidemiologic Studies-Depression, and Korean Sleep Scale(Oh, et al 1998). The sample consisted of 345 women with a mean duration of rheumatoid arthritis for 10.06 years and a mean age of 49.64 years. SPSS win and Win LISREL were used for the data analysis. Structural equation modeling revealed the overall fit of the model. Pain predicted fatigue directly and indirectly through disability, depression, and sleep disturbance. Disability, sleep disturbance predicted fatigue only directly, while depression only indirectly through disability and sleep disturbance. Also morning stiffness and symptom duration predicted fatigue through disability and depression. All predictors accounted for 65% of the variance of fatigue. Depression, pain, and disability predicted sleep disturbance. Depression had reciprocal relationship with disability and they both were predicted by pain directly and indirectly. In summary, pain, depression, disability, sleep disturbance, morning stiffness, and symptom duration contributed to the fatigue of patients with rheumatoid arthritis. The best predictor of fatigue was pain. This finding indicates that the modification of pain, depression, disability, sleep disturbance, morning stiffness could be nursing intervention for relief or prevention of fatigue.

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A Study On the Operating Room Nurses' Performances of Duties and Their Fatigue (수술실간호사의 직무수행과 피로에 관한 연구)

  • Park, Jeong Sook
    • Korean Journal of Occupational Health Nursing
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    • v.6 no.2
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    • pp.110-127
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    • 1997
  • The aim of this study is to present the basic datum for the promotion of effectiveness and improvement of nursery tasks, by grasping the situation of operating room nurses tasks and the degree of their fatigue. For these researches, 70 nurses out of the operating rooms of 3 university-affiliated hospitals-two in Seoul and one in Pusan, were chosen at random by a non-probability sampling method. These researches were done from April 14 to April 26 in 1997 by questionairing method. The questionaire was composed of 30 items, which asks the examinees of their physical, mental, and neurosensory symptoms, with 10 items respectively. The reliability of the research instrument was turned out very high with Cronbach's ${\alpha}=.9376$. The datum were electronically processed using Statistics Program for Social Sciences(SPSS). The analysis of datum in this study has a general character, in which the demosociological character and the special ex-officio character was calculated by frequency and percentage. The situation of tasks in operating rooms was calculated by frequency and percentage. The fatigue of operating room nurses was calculated by average and standard deviation. To compare the fatigue with regard to the character of operating room nurse's tasks, t-test and F-test(ANOVA) were used after the character of variations, and the variations at the level of P<.05 which might have some meaning was verified after the fact with Duncan's Multiple Range(DMR). The results of this research are as follows : 1) The nurses working in operating rooms show their fatigue in three fields-in Group I physical symptoms 3.28, in Group III neurosensory symptoms 2.85, and in Group II mental symptoms 2.73, which shows I Dominant type (general type). 2) They complain, in Group I they are "feeling the heavy legs," 3.28 and in Group II they "occasionally forget soon what to do," 3.09. and in Group III, they "feel lumbago," 3.47, which is the highest rate of the three. The highest rate results from the character of their tasks, in which they have to move rapidly the heavy appliances and do their jobs standing many hours, especially wearing heavy radiation protector. 3) As to transportation, subway using group feel the greatest fatigue, 3.18(F=4.315, P=.008). 4) As to department, nurses in the orthopedic's surgery part feel the greatest fatigue, 3.26(F=2.040, P=.050). 5) As to the change of physical symptoms, the group answering that they found physical abnormality after working in operating rooms show the greatest fatigue, 3.12(t=-3.13, P=.003). 6) At to the general circumstances, the group answering that they receive insufficient consideration on their physical abnormality in their department, show the greatest fatigue, 3.10(F=3.200, P=0.47). 7) As to the relation with superior officers, the group answering that their superior officer has an impetuous temperament, show great fatigue, 3.11(F=4.855, P=.011). 8) As to the time of feeling fatigue, the fatigue reaches the highest point 1~2 hours after operations, 3.04(F=2.703, P=.046). 9) When they feel fatigue after scrub nurse duties, they feel the greatest fatigue 2 hours after the duties, 3.09( F=2.841, P=.038). 10) As to the operation instruments, when they use complex instruments borrowing from the outside in addition to the basic instruments, their fatigue becomes the greatest, 3.09(F=7.831, P=.000). 11) As to the kind of operation, when they participate in orthopedic's surgery operations, they feel the greatest fatigue, 3.18(F=4.362, P=.000). With the above results, it is proved that the degree of operating room nurses' fatigue is considerably high. So it may be concluded that the measure for lessening the fatigue should be find immediately, not on the level of personal matters but on the level of hospital nursing administration.

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Fatigue Crack Localization Using Laser Nonlinear Wave Modulation Spectroscopy (LNWMS)

  • Liu, Peipei;Sohn, Hoon;Kundu, Tribikram
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.6
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    • pp.419-427
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    • 2014
  • Nonlinear features of ultrasonic waves are more sensitive to the presence of a fatigue crack than their linear counterparts are. For this reason, the use of nonlinear ultrasonic techniques to detect a fatigue crack at its early stage has been widely investigated. Of the different proposed techniques, laser nonlinear wave modulation spectroscopy (LNWMS) is unique because a pulse laser is used to exert a single broadband input and a noncontact measurement can be performed. Broadband excitation causes a nonlinear source to exhibit modulation at multiple spectral peaks owing to interactions among various input frequency components. A feature called maximum sideband peak count difference (MSPCD), which is extracted from the spectral plot, measures the degree of crack-induced material nonlinearity. First, the ratios of spectral peaks whose amplitudes are above a moving threshold to the total number of peaks are computed for spectral signals obtained from the pristine and the current state of a target structure. Then, the difference of these ratios are computed as a function of the moving threshold. Finally, the MSPCD is defined as the maximum difference between these ratios. The basic premise is that the MSPCD will increase as the nonlinearity of the material increases. This technique has been used successfully for localizing fatigue cracks in metallic plates.

Influence of high-cycle fatigue on the tension stiffening behavior of flexural reinforced lightweight aggregate concrete beams

  • Chen, How-Ji;Liu, Te-Hung;Tang, Chao-Wei;Tsai, Wen-Po
    • Structural Engineering and Mechanics
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    • v.40 no.6
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    • pp.847-866
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    • 2011
  • The objective of this study was to experimentally investigate the bond-related tension stiffening behavior of flexural reinforced concrete (RC) beams made with lightweight aggregate concrete (LWAC) under various high-cycle fatigue loading conditions. Based on strain measurements of tensile steel in the RC beams, fatigue-induced degradation of tension stiffening effects was evaluated and was, compared to reinforced normal weight concrete (NWC) beams with equal concrete compressive strengths (40 MPa). According to applied load-mean steel strain relationships, the mean steel strain that developed under loading cycles was divided into elastic and plastic strain components. The experimental results showed that, in the high-cycle fatigue regime, the tension stiffening behavior of LWAC beams was different from that of NWC beams; LWAC beams had a lesser reduction in tension stiffening due to a better bond between steel and concrete. This was reflected in the stability of the elastic mean steel strains and in the higher degree of local plasticity that developed at the primary flexural cracks.

Statistical Fracture Analysis of Turbine blade (터어빈 블레이드의 통계적 파괴 분석)

  • Choi, Jae-Ung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.2
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    • pp.101-106
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    • 2006
  • The optimum design of turbine blade at minimized fatigue life can be derived by the statistical fatigue analysis in this study, The optimum value of positions in the axes of X and Y at turbine blade can be found by design of experiments on the condition that the value of fillet radius is fixed to minimize the fatigue life. The degree of uncertainty about process at the factors in the axes of X and Y can be calculated by six sigma analysis. The optimum value of fillet radius is determined by utilizing the robust design at uncertain condition. It is concluded that maximum von Mises stress can decreased by 20% and the fatigue life can be double.

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