• Journal of Ocean Engineering and Technology
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• v.25 no.6
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• pp.49-55
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• 2011

In order to analyze feasibility of replacing a conventional 6-mm Ti bar with a 5-mm bar, a series of rotating bending fatigue tests were carried out on Ti-6Al-4V bars by strengthening the fatigue performance using a special technique called UNSM (Ultrasonic Nanocrystal Surface Modification). The results of S-N curves clearly showed that the performance of the 5-mm titanium specimen was similar to that of the 6-mm specimen when the UNSM treatment was applied. The 5-mm treated specimen converged with small scattering band into the linear line of the non-treated 6-mm one. Below the fatigue life of $10^5$ cycles, the UNSM treatment did not show any significant superiority in the bending stress and fatigue life. However, over the fatigue life of $10^5$ cycles, the effect of UNSM was superior for each fatigue life, and the bending stress became longer and higher than that of the untreated one. In the case of 6-mm Ti-bar with UNSM, the fatigue limit was about 592 MPa, and there was fatigue strength increase of about 30.7% at the fatigue life of $10^4$ cycles compared to the untreated 6-mm bar. Therefore, the compressive residual stress made by the UNSM in Ti-6Al-4V increased the fatigue strength by more than 30%.

• Child Health Nursing Research
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• v.10 no.1
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• pp.80-88
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• 2004

Purpose: The purpose of this study was to explore the fatigue of the mothers of the hospitalized children's mothers in descriptive study. Method: Two hundred eighty three mothers who take care of the hospitalized children in three University hospitals were enrolled from June, 1 to October, 30, 2003. Data were collected using a questionnaire titled 'Symptom Table on Fatigue Perception' designed by the Fatigue Research Committee of Japan, consisted of a total 30 items categorized into three sub-dimensions: the physical, the psychological and the neuro-sensory. SPSS was used for the analysis of data with 0.05 of significance. Result: 1) The mean average fatigue score of subjects was 1.94(SD:.48): the physical fatigue revealed the highest value with a mean of 2.19(SD:.57), followed by psychological fatigue with a mean score of 1.85(SD:.52), neuro-sensory fatigue with a mean of 1.79(SD:.51). 2) With the respect to the general characteristics of hospitalized children and mothers, there were statistically significant differences in the mothers' fatigue perception by the child sex(t=-2.697, p=.008), the character of child(F=9.032, p=.000), the child condition compared to pre-hospitalization(F=3.523, p=.031), with or without support in domestic households(t=-1.981, p=.049), the amount of sleeping time(t=2.704, p=.007), and with or without of night-time sleep disturbance because of the child hospitalization(t=2.082, p=.038). Conclusion: These results suggest that health care professional need to be aware of the persistent presence of the maternal fatigue related to the child hospitalization and the factors worsen the degree of the fatigue.

• Child Health Nursing Research
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• v.9 no.1
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• pp.36-45
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• 2003

The purpose of this study was to explore the various aspects of the fatigue in the mothers of infants and toddlers in descriptive study. Three hundred eighty mothers who visited the public primary health care center in subrural area were enrolled from October, 2001 to June, 2002. Data were collected using a questionnaire titled 'Symptom Table on Fatigue Perception' designed by the Fatigue Research Committee of Japan, consisted of a total 30 items categorized into three subdimensions: the physical, the psychological and the neuro-sensory. SPSS was used for the analysis of data with 0.05 of significance. The results were as follows: 1. The mean average fatigue score of subjects was 1.81(SD:.41): the physical fatigue revealed the highest value with a mean of 1.92(SD:.50), followed by psychological fatigue with a mean score of 1.79(SD:.48), neuro- sensory fatigue with a mean of 1.72(SD:.44). 2. With the respect to the general characteristics of subjects, there were statistically significant differences in the mothers' fatigue perception by with or without a job or not(t=2.213, p=.028), the number of children(t=-2.157, p=.032), the degree of spouse support in domestic households(F=3.315, p=.045), the degree of spouse support in the care of children(F=12.616, p=.000), and the amount of sleeping time(t=.130, p=.000). These results suggest that health care professional need to be aware of the persistent presence of the maternal fatigue related to the child rearing and the factors worsen the degree of the fatigue.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.55-63
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• 2000

Objectives : Fatigue is a common symptom experienced by everyone. Nevertheless, clinicians have a tendency of ignoring it since fatigue itself is not considered a distinct disease. Actually, some limited research about chronic fatigue syndrome has been made within the country, but in reality, the probability of getting this syndrome is still considered very low due to the strict diagnosis standard. Therefore, there are tremendous numbers of patients who do not get enough attention from clinicians for their fatigue symptoms only because technically they do not belong to the syndrome. Therefore, a basic statistical database must be compiled and patient management programs must be developed. To accomplish this, we conducted this study by measuring degree of fatigue, clinical characteristics and processes of Oriental medical treatment of fatigue patients. Methods : The objects of this study were selected from the new patients who entered the tonification Clinic in Kynnghee Oriental Medical Center between August 11, 2000 and October 7, 2000. Their main complaint was fatigue and they did not suffer from any physical or mental problem either historically or at the time of the study. The objects were divided into two groups based on duration of fatigue; fatigue under 6 months is considered as acute fatigue and fatigue for longer than 6 months is chronic fatigue. The prepared survey sheet for measuring fatigue degree was distributed to the patients with their consent. The patients were divided again into three subgroups : the fIrst group went through 1st test and constitution test after tonification clinic; the second one went into constitution test skipping Ist measuring test; the third one went into only tonification clinic with neither 1st measuring test nor constitution test. Results : The total number of object patients was 47 and 80% of them were considered as 'fatigue patients' by the Chalder scale. Among all patients, 29.5% requested treatment for chronic fatigue, which is over 6 months. The average of scale II for all patients was 14.8, which indicates moderate fatigue. The averages of scale II-1, II-2, II-3 were respectively 7.5, 5.9, and 3.7 so the most common complaint was physical fatigue. When compared scale II based on occupations, student group scored 6.9 and office man group scored 8.5 in scale II-1, physical fatigue, but it was not significant. Conclusions : Numerous number of patients have come to Oriental medical centers or hospitals in Korea. Therefore, deeper statistical research and follow-up-monitoring are reqnired in the Oriental medical academic world. In this study, among all patients who entered the tonification Clinic in Kyunghee Oriental Medical Center, 29.5% requested treatment for chronic fatigue, which is over 6 months. This kind of statistical report is the first time trial in the Oriental medical academy world. Through these steps, more objective treatment can be made and standards of prognosis assessment can be established.tablished.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.721-724
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the plate at the end.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.668-671
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• 1995

In this study, the fatigue charateristics of weld specimen was studied experimentally by using the various specimen types. The specimen type were tensile shesr(TS) specimen, cross tension(CT) specimen, and T typr (TT) specimen. Tensile test and fatigue test were carried out and microstucture was investigated. Finite element method was used to investigate stress distribution near nugget edge. Finally fracture mechanics approach was tried to the various specimen types.

• 연구논문집
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• s.34
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• pp.59-68
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• 2004

The hot spot stress approach and the notch strain approach are discussed with some results of them. And a stress model that can be applicable to several types of weld joints with single S-N curve of the base material. The stress model uses the geometric characteristics of the stress distribution vicinity of weld joints. The model was applied to five different weld joins(the base material is SM490B). By the representative stress, the experimental fatigue data are plotted very closely to the S-N curve of the base material.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.656-658
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• 1999

This paper presents musculotendon model to show the decline in muscle force during functional electrical stimulation (FES). It represent muscle activation and contraction concepts including muscle fatigue. A muscle fatigue term in activation dynamics as a function of the intracellular acidification and the pulsewidth of stimulation pulses change activation to decline muscle force. The computer simulation shows that muscle force decline in stimulation time.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.273-277
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• 1993

Fitigue behavior of soil-cement based pavement due to repeatitive traffic loads is studied. Finite element method is employed to analyze the pavement system including base, subbase, and soil layers. The calculated stresses are then used to evaluate the fatigue life of a pavement system. For the study is needed to determine accurately the fatigue characteristic of various soil-cement systems.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.692-699
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• 2005

In order to evaluate that factors such as span length, member type and train loading affect on fatigue of steel railway bridges, in this paper, a series field tests were carried out for some plate girder bridges. From the result estimated by rainflow counting method to analyses real strain-time curve obtained from the field test, it was known that the fatigue effect is more significant in the bridge having short span length and the secondary members regardless of train load types.