• The Journal of the Korea Contents Association
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• v.20 no.7
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• pp.547-559
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• 2020

Social Networking Service (SNS) is a part of our daily lives, with their positive and negative impacts. This study investigates SNS fatigue in men and women of different cultural backgrounds as well as the relationship between SNS fatigue and the intentions to cease SNS activities. The study results show that during SNS activities, women are more concerned for their reputation; participants with East Asian cultural backgrounds experience burdens with respect to relationships, and participants with Western cultural backgrounds experience fatigue with respect to privacy concerns. No statistical significance was identified between SNS fatigue and the intentions to cease SNS activity; although people experienced fatigue, they did not desire to stop SNS use. This study reveals that culture and gender impacts SNS fatigue, and few people quit SNS despite the fatigue.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.28-33
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• 2016

The spiropyran is a typical material having photodegradation properties in the process of photochromism. The spiropyran has been utilized in various applications such as optical switch, optical memories, and biosensor because of its remarkable stability, fast responsive time, stronger color change, and photo-induced controllability. However, the spriropyran is photodegraded by the repetitive optical irradiation. The photodegradation of spiropyran have been investigated by using UV-Visible spectroscopy, nuclear magnetic resonance (NMR), and Raman spectroscopy. Herein, the properties of spiropyran were characterized by using terahertz time-domain spectroscopy (THz-TDS) in the terahertz frequency region. In terahertz region, the measured absorbance of spiropyran was increased due to the photodegradation induced by the repetitive UV irradiation. The absorbance tendency of spiropyran in the terahertz frequency region was compared with that in the visible region, and they were completely opposite to each other.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.49-60
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• 2017

As well as the strength check, fatigue life check is also mainly required for designing mooring lines of the floating structures. In general, forces which induce dynamic structural response significantly affect to fatigue design of the mooring lines. So, waves are mainly considered as the governing loading for fatigue design of the mooring lines. In this study, characteristics of the fatigue damage of the mooring lines for submerged floating tunnels (SFT) under irregular waves are investigated. For this study time domain hydrodynamic analysis is used to obtain motion of the tunnel and tension and stresses of the mooring lines under the specific environmental conditions. Also, the Rainflow-counting method, the Palmgren-Miner's rule, and S-N curves for floating offshore structures presented by DNV recommendation is applied to calculate the fatigue damage due to the fluctuating stresses. Referring to the design plactice of the tendon pipes for TLP (tension-leg platform), which is very similar structural system to SFT, it is assumed that a 100 year return period wave attacks the SFT systems during 48 hours and the fatigue damages due to the environmental loading are calculated. Following the analysis sequence, the effects of the tunnel draft, spacing and initial inclination angle of the mooring lines on the fatigue damage under the specific environmental loadings are investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.264-274
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• 2018

This study constructed a prediction model based on covariance structure to identify the causal relationship between job stress, fatigue, burnout, and job satisfaction on turnover intention in nurses working in general hospitals. The study subjects were 648 nurses at a general hospital in D city. Data collection was surveyed by using self-administered questionnaires structured during the period from November 1, 2016 to December 31, 2016. As a result, the level of turnover intention was significantly higher in the group showing higher job stress, fatigue, and burnout and significantly higher in the group showing lower job satisfaction. The turnover intention of subjects showed a significant positive correlation with job stress, fatigue, and burnout but showed a negative correlation with job satisfaction. As a result of covariance structure analysis, job stress had greater influence on turnover intention than fatigue, burnout, and job satisfaction. Higher job stress, fatigue, and burnout and lower job satisfaction were associated with increased turnover intention. The results of this study show that the turnover intention of general hospital nurses is significantly related to job stress, fatigue, burnout, and job satisfaction. In particular, job stress had a greater effect on turnover than fatigue, burnout, and job satisfaction. Therefore, in order to lower the turnover intention of general hospital nurses, it is necessary to seek ways to mitigate job stress.

• Composites Research
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• v.31 no.6
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• pp.332-339
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• 2018

Fiber metal hybrid laminate (FML) can be used as an economic material with superior mechanical properties and light weight than conventional metal by bonding of metal and FRP. However, there are disadvantages that it is difficult to predict fracture behavior because of the large difference in properties depending on the type of fiber and lamination conditions. In this paper, we study the failure behavior of hybrid materials with laminated glass fiber reinforced plastics (GFRP, GEP118, woven type) in Al6061-T6 alloy. The Al alloys were coated with GFRP 1, 3, and 5 layers, and fracture behavior was analyzed by using a static test and a low cycle fatigue test. In the low cycle fatigue test, strain - life analysis and the total strain energy density method were used to analyze and predict the fatigue life. The Al alloy did not have tensile properties strengthening effect due to the GFRP coating. The fatigue hysteresis geometry followed the behavior of the Al alloy, the base material, regardless of the GFRP coating and number of coatings. As a result of the low cycle fatigue test, the fatigue strength was increased by the coating of GFRP, but it did not increase proportionally with the number of GFRP layers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.434-439
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• 2021

We assessed the effects of intravenous (IV) ascorbic acid administration on fatigue in women undergoing laparoscopic myomectomy. We analyzed the secondary endpoint results of a randomized, double-blind, placebo-controlled trial. Fifty patients undergoing laparoscopic myomectomy received IV ascorbic acid (2g) or placebo (randomly 1:1 ratio) intravenously during surgery. On day 2 post-surgery, we measured the level of fatigue using the Brief Fatigue Inventory-Korean version. Forty-five women (experimental arm 23, control arm 22) were eligible for analysis after 5 women (experimental arm 2, control arm 3) were excluded due to withdrawal of consent, cancellation of surgery or non-measurement of the endpoints. The baseline and operative characteristics were similar between arms and the global fatigue score of the experimental arm (4.56 ± 2.63) was not significantly different from that of the control arm (5.21 ± 2.02, P = 0.351). However, the fatigue score of the experimental arm tended to be lower than that of the control arm in most domains. IV ascorbic acid administration did not significantly reduce the level of fatigue in women undergoing laparoscopic myomectomy as compared to placebo. More research is needed to better understand the effects of ascorbic acid on fatigue in surgical patients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3148-3154
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• 2010

This paper presents the probabilistic analysis for fatigue life of Glass/Epoxy laminates with impact-induced damage. For this, a series of impact tests were perfomed on the Glass/Epoxy laminates using instrumented impact testing machine. Then, tensile and fatigue tests carried out so as to generate post-impact residual strength and fatigue life. Two Parameter Weibull distribution was used to fit the residual strength and fatigue life data of Glass/Epoxy composite laminates. The residual strength was affected by impact energy and their variance decreased with increasing of impact energy. The fatigue life of impacted laminates was greatly reduced by impact energy and this trend depended on applied stress amplitude. Additionally, the variation of fatigue life was gradually decreased with the applied stress amplitude.

• Composites Research
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• v.12 no.3
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• pp.26-35
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• 1999

The static strength and fatigue life of repaired graphite/epoxy laminates are observed using tensile coupon. The lay-up of investigated laminates was [$0^{\circ}$/$\pm$$45^{\circ}$/$90^{\circ}$]$_s$. Static strength was measured from the specimens prepared by various repair techniques such as precured-single patch, precured-double patch and cure-in-place methods. The strength was recovered to the extent of 60~80 % of unnotched case. Fatigue life was also measured from the laminates repaired with cure-in-place method. Hwang and Han's MFLPE 1(modified fatigue life prediction equation 1), which was based on the fatigue modulus degradation model and reference modulus, was chosen for fatigue life prediction of repaired specimen and compared with the conventional fatigue life equation such as S-N curve and Basquin's relation. The MFLPE 1 has better agreement with experimental data than S-N curve and Basquin's relation.

• Journal of Korean Society of Steel Construction
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• v.14 no.3
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• pp.453-461
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• 2002

This study investigated the fatigue stength of non-load carrying cruciform welded joints, which was maunfactured using the SM570 and POSTEN80 high strengh steel. Factors such as fatigue strength, fatigue crack initiation and propagation, thickness effect, and the relatioinship between the static strength and the fatigue strength were examined and compared with previous fatigue testing results. Results showed that the fatigue strength of SM570 and POSTEN80 steel are higher than the grade represented on the design specification. It is also identified the size effect and the dependence of the static stength in a few cases.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.2
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• pp.79-85
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• 1996

Prediction of fatigue life and monitoring of fracture process for adhesively bonded CFRP composites joint have been investigated by analysis of acoustic emission signals during the fatigue and tension tests. During fatigue test, generated acoustic emission is related to stored elastic strain energy. By results of monitoring of AE event rate, fatigue process could be divided into two regions, and boundaries of two regions, fatigue cycles of the initiation of fast crack growth, were 70-80% of fatigue life even though the fatigue life were highly scattered from specimen to specimen. The result shows the possibility of predicting catastrophic failure by acoustic emission monitoring.