• 항공우주의학회지
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• 제30권2호
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• pp.54-60
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• 2020

Pilot fatigue is a great hazard to aviation safety. In recent years, long-distance fights have been increasing and flight hours have been increasing, which has made fatigue issues important. International organizations in the aviation sectors (ICAO, FAA, IATA etc.) recommend management of fatigue within the SMS (Safety Management System) framework. A scientific and systematic approach to measuring fatigue is required as a prerequisite to preparing safety management measures for pilot's fatigue. Therefore, in this study, I would like to consider recent trends and implications for fatigue measurement. First, I aimed to consider recent the accident cases related to fatigue. Second, I also considered how to measure the pilot's fatigue. Finally, the direction of the countermeasures against fatigue through fatigue measurement was developed and suggested.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제4권2호
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• pp.143-152
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• 2000

As muscular contraction is sustained, the Fourier spectrum of the myoelectric signal is shifted toward the lower frequency. This spectral density is associated with muscle fatigue. This paper describes a quantitative measurement method that performs the measurement of localized muscle fatigue by tracking changes of median frequency based on stationary wavelet transform. Applying to the human masseter muscle, the proposed method offers the much information for muscle fatigue, comparing with the conventional FFT-based method for muscle fatigue measurement.

• 대한간호학회지
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• 제26권4호
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• pp.868-877
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• 1996

This study was done to analyze research trends and to suggest future perspectives for nursing research on fatigue. The author reviewed 31 Korean and foreign research papers which have been published in the literature since 1970. An analysis of the study focused on the type of research subjects, type of study design. measurement instrument, and its correlated parameters. The results of the study are summarized as follows : First, within all of the studies analayzed, 14 studies were publised in Korea and 17 were published abroad. The number of studies done abroad have been increasing rapidly since 1991. Second, an analysis of the research design of the studies showed, eight studies each, Korean and foreign used survey design. Two Korean studies and seven foreign studies used a correlational design. Four comparative studies were done in Korea, but only two experimetal studies were performed abroad. Therefore, it was found that the trend of the study design used is survey design and there are more correlational studies done abroad than in Korea. Third, the type of the study subjects ; 11 Korean and three foreign studies dealt with healthy people. In addition, three Korean and 14 foreign studies investigated patients with various illnesses. It was found that patients with various illnesses were studied more frequently in foreign studies than in Korean studies. Fourth, the measurement tool used in the Korean studies ; 13 studies used a testible tool to assess patients' subjective symtoms or complaints of fatigue. The most commonly used tool used in 10 studies, was the Fatigue Self-Perception Scale, which was designed by the Labor and Health Institute of Japan. The Visual Analogue Scale was used in two studies, and Piper Fatigue Scale, addtional with physiologic parameters, was used in one study. In the foreign studies, subjective measurement tools were used in 16 studies. A combination of a subjective measurement tool with objective parameters was used in ten studies. For the subjective measurement tool used in the foreign studies, a specific measurement tool developed by the researcher which was used in seven studies. Either Rhoten Fatigue Scale or the Visual Analog Scale were used in three studies. Additionally, in order to identify the relationship between fatigue and psychological factors, The Profile of Mood State was used in three studies. Beck Depression Inventory was used in two studies. The Self Rated Depression Scale, developed by Zung, was used in one study and other measurement tools were used to measure various psychological parameters. Rhoten fatigue Checklist was also used to observe behavior patterns. Lastly, nine studies identified correlations between fatigue and other parameters. A significant correlation was found between fatigue and psychological factors such as depression, and pain. As a result of the above findings, it can be said that research trends on fatigue are increasing internationally. The selected study designs are survey studies both in Korea and abroad. There are more correlational studies abroad than in Korea. In addition, subjective measurement tools and objective parameters are used variously and combined with each other. had, there is a significant correlation between fatigue and psychological factors such as depression, and pain. More survey and correlational studies need to be done to identify the relationship of fatigue in patients with various condition or diagnoses and to suggest a scientific basis for nursing interventions with fatigue. Also, a tool to assess patient's subjective, objective, and behavioral aspects on fatigue needs to be developed.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1994년도 춘계학술대회논문집
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• pp.32-37
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• 1994

This paper surveys the various methodologies for the objective measurement of visual fatigue. Visual fatigue is a psychophysiological symtom caused by the excessive use of eyes and it can be used as an important measure of the effectiveness and the safety of visual displays. The purpose of this paper is to compare the various visual fatigue measurement methodologies in a sense of the suitability for the ergonomic research. The measurement methodologies based on accommodation, convergence, visual evoked potential, eye movement, eye blinking, and flicker fusion were discussed and compared.

• 대한인간공학회지
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• 제30권1호
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• pp.195-202
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• 2011

Objective: The aim of this study is to investigate and review the previous researches about objective measuring fatigue caused by visual stimuli. Also, we analyze possibility of alternative visual fatigue measurement methods using facial expression recognition and gesture recognition. Background: In most previous researches, visual fatigue is commonly measured by survey or interview based subjective method. However, the subjective evaluation methods can be affected by individual feeling's variation or other kinds of stimuli. To solve these problems, signal and image processing based visual fatigue measurement methods have been widely researched. Method: To analyze the signal and image processing based methods, we categorized previous works into three groups such as bio-signal, brainwave, and eye image based methods. Also, the possibility of adopting facial expression or gesture recognition to measure visual fatigue is analyzed. Results: Bio-signal and brainwave based methods have problems because they can be degraded by not only visual stimuli but also the other kinds of external stimuli caused by other sense organs. In eye image based methods, using only single feature such as blink frequency or pupil size also has problem because the single feature can be easily degraded by other kinds of emotions. Conclusion: Multi-modal measurement method is required by fusing several features which are extracted from the bio-signal and image. Also, alternative method using facial expression or gesture recognition can be considered. Application: The objective visual fatigue measurement method can be applied into the fields of quantitative and comparative measurement of visual fatigue of next generation display devices in terms of human factor.

• Safety and Health at Work
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• 제3권1호
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• pp.31-42
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• 2012

Objectives: The objectives of this study were to determine the psychological fatigue and analyze muscle activity of production workers who are performing processes jobs while standing for prolonged time periods. Methods: The psychological fatigue experienced by the workers was obtained through questionnaire surveys. Meanwhile, muscle activity has been analyzed using surface electromyography (sEMG) measurement. Lower extremities muscles include: erector spinae, tibialis anterior, and gastrocnemius were concurrently measured for more than five hours of standing. Twenty male production workers in a metal stamping company participated as subjects in this study. The subjects were required to undergo questionnaire surveys and sEMG measurement. Results: Results of the questionnaire surveys found that all subjects experienced psychological fatigue due to prolonged standing jobs. Similarly, muscle fatigue has been identified through sEMG measurement. Based on the non-parametric statistical test using the Spearman's rank order correlation, the left erector spinae obtained a moderate positive correlation and statistically significant ($r_s$ = 0.552, p < 0.05) between the results of questionnaire surveys and sEMG measurement. Conclusion: Based on this study, the authors concluded that prolonged standing was contributed to psychological fatigue and to muscle fatigue among the production workers.

• 대한기계학회논문집
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• 제15권1호
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• pp.209-217
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• 1991

본 연구에서는 이러한 제반 문제점들을 보완하여 피로균열 선단의 국소영역에 서의 변형율상태를 실시간적으로 정도 높게 측정할 수 있는 새로운 변형율측정법인 미 소원형격자변형율측정법(fine dot grid strain measurement method)을 이용하였다. 그 결과, 균열선단의 국소영역에서의 피로변형율상태를 명확히 밝혀냄은 물론 이를 기 초로 하여 국소피로변형율장을 대표할 수 있는 피로변형율확대계수 .DELTA.A를 제안하였으 며 그 유효성에 대하여 명백히 하였다.

• 한국해양공학회지
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• 제16권2호
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• pp.60-66
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• 2002

The remote measurement system(RMS) as a new experimental method is limited in its application to crack measurement at elevated temperatures because of the oxide layer on the specimen surface. Since TiAIN and Cr coating layers have a high resistance to oxidation and wear, this paper proposed a TiAIN and Cr coating technique for specimens to facilitate the measurement of crack growth behavior using RMS. To investigate the effects of the coating layer, tension and fatigue tests were carried out at room temperature and at $538^{\circ}C$. The test material was 1Cr-1Mo-0.25V steel which is widely used as a turbine rotor material. From the experimental results, it was found that the mechanical properties of the TiAIN and Cr coated specimens were similar to those of the substrate. Accordingly, the TiAIN and Cr coated layer had hardly any influence on the fatigue crack propagation.

• Journal of Welding and Joining
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• 제30권6호
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• pp.80-85
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• 2012

Fatigue cracks in structural components are the most common cause of structural failure when exposed to fatigue loading. In this respect, fatigue crack detection and structural health assessment are very important. Currently, various smart materials are used for detecting fatigue crack and measurement of SIFs(Stress Intensity Factors). So, this paper presented a measurement of SIFs using MFC(Micro Fiber Composite) sensor which is the one of the smart material. MFC sensor is more flexible, durable and reliable than other smart materials. The SIFs of Mode I(K I) as well as Mode II(K II) based on the piezoelectric constitutive law and fracture mechanics are calculated. In this study, the SIF values measured by MFC sensors are compared with the theoretical results.

• 한국안전학회지
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• 제15권1호
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• pp.132-139
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• 2000

In this study, the fatigue life assessments of steel railway bridge in Japan National Railway were carried out. This railway bridge has been under in service from 1957, and fatigue damages were occurred at bead toe of upper part of vertical stiffeners of stringers, bead toes of scallop in lower part of vertical stiffeners in stringers and crossings of cross beams and stringers. From this study, a series of field tests were carried out by stress history measurement about above mentioned points. And as a results of stress histogram analysis, cummulative fatigue damage rate and fatigue life of these members should be calculate quantitatively. And from this estimation technique, cummulative fatigue damage rate and fatigue life of this railway bridge were strongly affected in passing tonage every year and the histories of live load.