• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.623-629
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• 2008

New high strength bolts are required due to the development of the high strength steel, the ultra-thick steel plates, and the long-span bridge, though high strength bolts with tensile strength of 1,000 MPa are mainly used in construction site of every country. Consequently, in this study, we estimated the fatigue strength by performing fatigue test of slip-resistant splices with slip coefficients applying the newly developed F13T high strength bolts. The fatigue test satisfied the Category B requirements with the fatigue strength of slip-resistant splices. Also we analyzed the fatigue fracture characteristics of slip-resistant splices.

• Journal of Korean Society of Steel Construction
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• v.16 no.6 s.73
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• pp.847-855
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• 2004

The criterion or specification on fatigue design has been generally based on fatigue strength curve derived by tests on specimens with varying thickness (10-30mm). Making the plate thicker, however, also decreases fatigue strength. It has been noted from the test results and the results of the analysis by fracture mechanics that the effect of thickness cannot be bypassed. From the several fatigue strength curves of specimen tests, modification of fatigue strength on plate thickness has been proposed. In this study, fatigue tests on SM520C-TMC were carried out, and the effects of thickness were evaluated. Finally, in consideration of the thickness, the modification of fatigue strength was derived. Comparing the results of this paper with those of previous studies, an outline of the behavior obtained is similar to previous ones, but the rate of decrease is smaller.

• Korean Journal of Culture and Social Issue
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• v.12 no.3
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• pp.69-83
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• 2006

The purpose of the present driving simulation study was to investigate the effects of fatigue induced both by sleep deprivation and time-on-task on driver's driving performance. The results are as followings. First, although the drivers in almost every experimental conditions showed faster driving speed than that was required, the drivers in the sleep-deprivation and over 1-hour time-on-task condition drove slower than the target speed. Second, the drivers in the sleep-deprivation and over 1-hour time-on-task condition crossed the lane less frequently than those in the other conditions, they weaved more in the lane. Third, as the drivers became more fatigued both by sleep deprivation and continuous driving, they reported higher fatigue scores in the subjective fatigue ratings. The results suggested that although the drivers might adapt a compensative driving strategies when they were fatigued, their driving performances were indeed impaired, in general.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.1-10
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• 2005

In this study, accelerated pavement tester(APT) was performed on long-life asphalt pavements that can save maintenance and user costs by increasing the design life twice longer than conventional asphalt pavements. Basic material testings are first conducted on a high modulus base(HMB) mixture developed in this study. Four different pavement sections including thin and thick conventional and thin and thick HMB courses are constructed to compare the load-carrying capacities and to investigate the fatigue and rutting performances using an accelerated pavement tester. Tensile strain values at the bottom of base courses under the various loading levels are measured. The tensile strain values of the HMB sections are lower than those of the conventional sections. It is observed from the APT performed on the thin pavement sections that no significant cracks are developed up to the 180,000 cycles of a wheel load. In terms of rutting, only 3mm of rutting is developed in the thick HMB section while 5.3mm of rutting is developed in the thick conventional section at the 90,000 cycles of the wheel load. The HMB material developed in this study can be successfully used in the long-life asphalt pavements because of its excellent fatigue and rutting performances. It is estimated from a series of structural analysis that the use of the HMB material instead of the conventional base materials may reduce the asphalt thickness at least 5cm because of its better load-carrying capacity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.667-679
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• 2022

Fatigue damage analysis of ships includes parameters considering operational factors. Due to these operational variables, there is a difference between the fatigue damage estimated during the design stage and the actual accumulated fatigue damage. Likewise, there are various loading conditions for the real container ships, but at design stage the fatigue damage is calculated by applying the representative loading conditions. Moreover, although the difference in fatigue damages is expected when the actual and design loading conditions are applied, there are few studies on the contributions of the fatigue damage based on the loading conditions of container ships. In this paper, fatigue contributions were investigated from various cargo weight distributions. The hull girder loads calculated through seakeeping analysis and fatigue damages obtained by performing spectral fatigue analysis were identified under new loading conditions. As a result, it was found that the variation of cargo weight distribution in the container ship brought about changes in the hull girder loads and fatigue damage by affecting the hull girder stress.

• The Journal of the Convergence on Culture Technology
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• v.4 no.4
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• pp.11-20
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• 2018

The purpose of this study was to examine the effect of the application of cool dialysis on dialytic stability, feeling of fatigue, pruritus and dialysis adequacy in hemodialysis. Methods: The study design was nonequivalent control group pretest-posttest design. The subjects were 50 patients who were hospitalized to hemodialysis. The experimental group cool dialysis(n=25) and the control group received only the usual treatment (n=25). The collected data were analyzed using independent t-test to examine study hypothesis. Results: The level of dialytic stability (F=5.53, p=.023) and feeling of fatigue (F=4.01, p<.001) in the experimental group were significantly different from that of the control group. However, the level of pruritus(F=.74, p=.394) and dialysis adequacy(F=1.02, p=.327) in the experimental group were not different from that of the control group. Conclusion: The study findings confirm that cool dialysis as an effective intervention alleviating dialytic stability and feeling of fatigue.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.352-354
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• 2021

코로나 19의 확산으로 인해 온·오프라인의 경계가 희미해짐과 동시에 비대면 형태 서비스가 확산되고 있으며, 교육 분야에서도 비대면 화상 강의와 원격수업의 적용이 일상화되고 있다. 기존의 비대면 화상 강의 시스템의 경우, 피교육자 신원확인 미흡에 따른 비인가자 접근 및 교육 방해 행위가 발생하였고, 교육내용 및 보고서 등 교육자와 피교육자 간 송·수신 내용 노출의 위험성이 있으며, 대량의 트래픽 유발에 따른 수업 방해가 가능하여 보안상의 대책이 요구된다. 본 논문에서는 기존의 비대면 형태의 피교육자 신원확인 미흡에 따른 비인가 접근 및 교육 방해 행위와 교육자와 피교육자 사이의 송·수신 내용의 위험성을 해결하고, 대량의 트래픽 유발에 따른 수업 방해에 대한 보안대책으로 블록체인 기반 DID 비대면 실습교육 플랫폼 설계를 제안한다.

• Journal of Welding and Joining
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• v.6 no.3
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• pp.43-55
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• 1988

An experimental study was carried out to identify the fatigue fractue behavior of weld zone in generally rolled steel for marine structure. The bending an shear loads were applied simultaneously on the specimens to simulate real load condition for marine structure. The effect of the stress intensity factor under mode I with II loading condition on the initiation and the propagation of a crack were investigated, with particular emphaiss on mode II. When the $K_{II}$ stress intensiy factor in mode II was applied under mode I load condition, the growth behavior of a crack seems to be affected mainly by the anisotropic characteristic of materials. Especially, when the crack was located in and near the weld zone and parallel to th weld line, the propagation behaviour was turned out to be quite different from that of the base metal along the direction transverse to the weld line. In general, the propagation veiocity of the cracks in and near the weld zone was found to be slower that the velocity in base metal.

• Korean Journal of Poultry Science
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• v.10 no.2
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• pp.97-101
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• 1983

A study was conducted to investigate possibility of utilizing dried citrus peel (DCP) as an ingridient of broiler diets. Fresh citrus peels were collected from a citrus processing plant, and were sun-dried and ground. Both chemical analyses and a feeding trial were carried out. DCP was analyzed for proximate nutrients, amino acids and some minerals. In the feeding trial, a total of 192 day-old female broiler chicks of Manor strain was divided into 16 groups of 12 birds each. Each group was fed one of the 4 different levels(0, 2, 4 and 6%) of DCP replacing an equivalent amount of wheat bran in the diet with 4 replications for 6 weeks. Body weight gain, feed intake and feed efficiency of broilers fed different levels of DCP showed no significant differences among treatments. Immediately after termination of the feeding trial, cach bird was examined for shank color using Roche's Egg Yolk Color Fan. Shank color index of birds increased consistently (P＜0.05) as the level of DCP fed increased, indicating that DCP can be used as a source of pigments. It was concluded from the results that DCP could be used up to 6% in place of wheat bran in broiler diets without adverse effects.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.178-188
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• 2017

This study is a descriptive research on the subjects of hospital nurses to investigate the effect of job satisfaction and fatigue on their nursing professional attitudes. The subjects were 262 nurses working at five general hospitals in J and S cities. Data collection was conducted from December 2014 to January 2015 using structured questionnaires on job satisfaction, fatigue and nursing professional attitudes. As a result of the study, nurses' nursing profession attitude was high in 30 year old and married nurses, and in clinical experience of either less than a year or more than six years, and nurses' nursing profession attitude was higher in charge nurses and head nurses than in general nurses. The most influential factors affecting the nursing professional attitude were job satisfaction, clinical career, and fatigue in that order. These findings provide theoretical evidence to explain the importance of job satisfaction and fatigue variables in influencing factors on nursing professional attitude. Therefore, in clinical practice, it is necessary to develop and implement an education program to improve nursing professional attitudes by considering nurses' job satisfaction, clinical career and fatigue level.