• Title/Summary/Keyword: Fatigue Life Assessment

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An Effect of Steel Corrosion on Bond Stress-slip Relationship under Repeated Loading (반복하중하의 부착응력-슬립 관계에 미치는 철근 부식의 영향)

  • Kim, Chul-Min;Park, Jong-Bum;Chang, Sung-Pil;Kim, Jee-Sang
    • Journal of the Korea Concrete Institute
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    • v.22 no.2
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    • pp.179-186
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    • 2010
  • The bond between steel and concrete in reinforced concrete members is essential to resist external load, but the bond mechanism in reinforced concrete beams deteriorated by steel corrosion has not been clearly known yet. Most existing researches have dealt with the bond behavior of corroded steel under monotonic loading, but scarce are researches dealing with bond behavior of corroded steel under repeated loading. This study includes the experimental investigation on the bond behavior with respect to the various degrees of steel corrosion under repeated loading. According to the test results, the bond strength of corroded steel under monotonic loading increases as the rate of steel corrosion increases unless the splitting crack occurs. The slip versus number of load cycles relation was found to be approximately linear in double logarithmic scale, not only in specimens without steel corrosion but also in specimens with steel corrosion. The test results also show that the steel corrosion does not negatively affect the bond strength of corroded steel after repeated loading unless the splitting crack occurs. But the fatigue life decreases sharply after splitting crack occurs. This research will be helpful for the realistic durability design and condition assessment of reinforced concrete structures.

Quality of Life and Psychological Well-Being of Colorectal Cancer Survivors in Jordan

  • Abu-Helalah, Munir Ahmad;Alshraideh, Hussam Ahmad;Al-Hanaqta, Motasem Mohammad;Arqoub, Kamal Hasan
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.18
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    • pp.7653-7664
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    • 2014
  • Background: Colorectal ranked first among cancers reported in males and ranked second amongst females in Jordan, accounting for 12.7% and 10.5% of cancers in males and females, respectively. Colorectal cancer patients can suffer several consequences after treatment that include pain and fatigue, constipation, stoma complications, sexual problems, appearance and body-image concerns as well as psychological dysfunction. There is no published quantitative data on the health-related quality of life and psychological wellbeing of Jordanian colorectal cancer survivors. Method: This project was a cross-sectional study of colorectal cancer survivors diagnosed in 2009 and 2010. Assessment was performed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), the colorectal cancer specific module (EORTC QLQ-CR 29) and the Hospital Anxiety and Depression Scale (HADS). Data on potential predictors of scores were also collected. Results: A total of 241 subjects completed the study with mean age of $56.7{\pm}13.6$. Males represented 52.3% of study participants. A majority of participants reported good to high overall health; the mean Global health score was $79.74{\pm}23.31$ with only 6.64% of study participants scoring less than 33.3%. The striking result in this study was that none of the study participants participated in a psychosocial support group; only 4 of them (1.7%) were even offered such support. The mean scores for HADS, depression score, and anxiety score were $8.25{\pm}9$, $4.35{\pm}4.9$ and $3.9{\pm}4.6$, respectively. However, 77.1% of study participants were within the normal category for the depression score and 81.7% were within this category for anxiety score; 5.4% of participants had severe anxiety and 5.4% of them had severe depression. Discussion: Patients with colorectal cancer in Jordan have a good quality of life and psychological wellbeing scores when compared with patients from western countries. None of the colorectal cancer patients managed at the Ministry of Health received any formal counselling, or participated in psychological or social support programmes. This highlights the urgent need for a psychosocial support programme, psychological screening and consultations for patients diagnosed with colorectal cancer at the Ministry of Health Hospitals.

Cumulative Risk Assessment of Organophosphorus Pesticides in the Diet (식품을 통한 유기인계농약류의 동시노출위해성평가)

  • 이효민;한지연;윤은경;김효미;황인균;최동미;이강봉;원경풍;송인상
    • Journal of Food Hygiene and Safety
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    • v.16 no.1
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    • pp.21-26
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    • 2001
  • Risk assessment traditionally are conducted on individual chemicals; however, humans are exposed to multiple chemicals in daily life. The organophosphorus (OP) pesticides are considered in a single risk assessment because they act by a common mechanism of toxicity, and there is likely to be expose to multiple OP pesticides simultaneously or sequentially. The OP pesticides act by inhibiting the enzyme acetylcholinesterasc (AChE) and have available extensive database. AChE is widely distributed throughout the body, most importantly in the nervous system. Inhibition of AChE results in accumulation of acetylcholine in the nervous system that results in clinical signs of cholinergic toxicity, including increased salivation and lacrimation, nausea and vomiting, muscle fasciculation, lethargy and fatigue, among others. To conduct an exposure assessment for pesticides in the diet, we need to know the food consumption patterns of the populations, and the pesticide residue levels in the foods that are consumed. This study was conducted to identify cumulative dietary risk due to multiple OP pesticides that can be exposed through various foods. Total 22 food samples including cereals, vegetables and fruits were collected randomly two times from food markets in several sites (4 cities). The subjected foods were selected by regarding of highly consumed foods to general Korean people. The 12 OP pesticides including Acephate, Azinphos-methyl, Chlorpyrifos, and Diazinon were monitored. For the exposure assessment, general adult group of 60 kg body weight was regarded as target population and food consumption data suggested by Lee et al. (2000) were used as consumed value of individual food. Analyses of samples for OP pesticides have been carried out according to the multiclass multiresidue analysis method and acephate and methamidophos analysis method of Korea Food Code. In general the levels of OP pesticides found in the food samples were very low or not detected.

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Pre-Menstruation Discomforts Experienced by Women (여성이 경험하는 월경전 불편감)

  • Kim, Eun-Ha;Kim, Shin-Jeong
    • Women's Health Nursing
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    • v.7 no.4
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    • pp.631-641
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    • 2001
  • This study is to investigate women have pre menstruation discomfort, The period of this research was almost one month (from 25, August 2001 to 25, October 2001). The PAF (Premenstrual assessment form), which was made by Park, Myonng-Wha, used for this study. The confidence rate is Crombach's $\alpha$= .9773. Correcting research papers are analyzed by SPSS 7.5 program and normal feature of the subject is divided by frequency, percentage, mean, standard deviation, t-test and ANOVA. The results of this study are as follows; 1. The average age of the subjects is 26.47 age. 220 subjects(44.6%) have gastroenteric trouble like, enteritis, stomachache, laxity. 278 subjects usually have caffeine drink in routine life. 123 subjects(24.9%) have controlled their diet. The average age of the first plowing is 13.55 ages and distribution is between 10 years and 20 years. The average of the uncomfortable point is 2.84. The way to reduce the uncomfortable feeling on the menstruation is taking relax time. 2. All subjects have experienced pre menstruation discomfort, even the degree uncomfortable feeling is different. Through eighteenth categories on the research papers, average point 2.21 were calculated and many subjects have fatigue ($2.89{\pm}1.0614$) and normal physical uncomfortable ($2.84{\pm}1.0633$) and undercurrent water symptom and unsuitability ($2.45{\pm}0.9857$). 3. According to the result of this study, that shows statistical difference; age (F=2.56. p=.037). marriage (t=2.60, p=.009) the number of children(t=2.83, p=.005), stress level(F=13.03, p=.000) job(F=3.91, p=.020). monthly income(t=2.14. p=.032) uncomfortable degree on the menstruation (F=19.121, p=.000), use of contraceptive appliance or pill(t=-2.20, p=.043), schooling (F=3.30, p=.038). Further research is need to understand pie menstruation discomforts, the variables associated with them. And nursing intervention has to considered in program to reduces of pre-menstruation discomforts.

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Assessment of the Impact Factor and the Stress Histogram of Railway Bridges in Korea (국내 강철도 교량의 충격계수 및 응력빈도분포의 평가)

  • Choi, Jun Hyeok;Cho, Sun Kyu;Chang, Dong Il
    • Journal of Korean Society of Steel Construction
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    • v.9 no.4 s.33
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    • pp.489-500
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    • 1997
  • The number of railway bridges in Korea reaches to about 3,000. Among them, the ratio of steel bridges is about 47%. Most of the long span railway bridges take the truss type, its number is 15 in Korea. These bridges have more than 30 years service life, it is expected that the damages of cracks and corrosion is going. Therefore, the estimation of fatigue life with random stress is considered as significant subject in maintenance. In this paper, the random stress was measured in bridges and counted the stress cycles using the rainflow counting method So, the stress range frequencies and their equivalent stress are obtained and the amplification factor for the span length, bridge types and traveling speed is assessed by the dynamic testing. From the results, the stress range of the stringer and the lower chord is higher than the other members and the characteristics of the stress histogram is varied to the loading system and the amount of the passing through trains. And the impact effects are depended on the traveling speed as well as the span length.

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Assessment of Composite Material Flaws on the Type III Cylinders for Compressed Natural Gas Vehicles (압축천연가스자동차용 Type III 용기의 복합재 결함 평가)

  • Kim, Young-Seob;Kim, Lae-Hyun;Yang, Dong-Ju
    • Journal of Energy Engineering
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    • v.20 no.2
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    • pp.90-95
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    • 2011
  • This study was conducted to judge requalification of cylinders by assessing composite flaws such as scratches, cuts, and gouges damaging on the composite of Type III cylinders for compressed natural gas vehicles. As a result of the flaw tolerance test, all specimens have satisfied with minimum requirement cycles according to damage levels based on ISO 19078 and cyclic performance for pressure showed beyond twenty thousands in damage level 1 and 2, and did eighteen thousands to twenty-one thousands in damage level 3. Eight of twelve specimens failed the test due to composite flaws and the rest of the cylinders failed regardless of flaws. The results of Finite Element Method followed by the computer simulation indicated that the stress of 79.5 MPa calculated on the flaw model of $1.25\;mm{\times}200\;mm$ and the stress of 66.6 MPa on the non-flaw model when the service pressure applied to inside of cylinder. The difference between the models is about 19.37%. We concluded that this difference influences fatigue life and this flaw model is a critical value affecting cyclic performance of cylinders.