• Structural Engineering and Mechanics
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• 제50권6호
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• pp.835-852
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• 2014

Despite the availability of other transport methods such as land and air transportations, marine transportation is the most preferred and widely used transportation method in the world because of its economical advantages. In service, ships experience cyclic loading. Hence, it can be said that fatigue fracture, which occurs due to cyclic loading, is one of the most critical failure modes for vessels. Accordingly, this makes fatigue failure prevention an important design requirement in naval architecture. In general, a ship structure contains many structural components. Because of this, structural modeling typically relies on Finite Element Analysis (FEA) techniques. It is possible to increase fatigue performance of the ship structures by using FEA in computer aided engineering environment. Even if literature papers as well as rules of classification societies are available to assess effect of fatigue cracks onto the whole ship structure, analytical studies are relatively scarce because of the difficulties of modeling the whole structure and obtaining reliable fatigue life predictions. As a consequence, the objective of this study is to improve fatigue strength of a mercantile vessel against fatigue loads via analytical method. For this purpose, the fatigue life of the mercantile vessel has been investigated. Two different type of fatigue assessment models, namely Coffin-Manson and Morrow Mean stress approaches, were used and the results were compared. In order to accurately determine the fatigue life of the ship, a nonlinear finite element analysis was conducted considering plastic deformations and residual stresses. The results of this study will provide the designer with some guidelines in designing mercantile vessels.

• International Journal of Reliability and Applications
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• 제3권1호
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• pp.1-16
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• 2002

In reliability engineering, the bathtub-shaped hazard rates play an important role in survival analysis and many other applications as well. For the bathtub-shaped, initially the hazard rate decreases from a relatively high value due to manufacturing defects or infant mortality to a relatively stable middle useful life value and then slowly increases with the onset of old age or wear out. In this paper, we present a new two-parameter lifetime distribution function, called the Loglog distribution, with Vtub-shaped hazard rate function. We illustrate the usefulness of the new Vtub-shaped hazard rate function by evaluating the reliability of several helicopter parts based on the data obtained in the maintenance malfunction information reporting system database collected from October 1995 to September 1999. We develop the S-Plus add-in software tool, called Reliability and Safety Assessment (RSA), to calculate reliability measures include mean time to failure, mean residual function, and confidence Intervals of the two helicopter critical parts. We use the mean squared error to compare relative goodness of fit test of the distribution models include normal, lognormal, and Weibull within the two data sets. This research indicates that the result of the new Vtub-shaped hazard rate function is worth the extra function-complexity for a better relative fit. More application in broader validation of this conclusion is needed using other data sets for reliability modeling in a general industrial setting.

• Journal of Chest Surgery
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• 제23권2호
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• pp.253-259
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• 1990

Between January, 1970 and August, 1989, a total of 81 patients whose age were more than 20 years of life, received total correction for tetralogy of Fallot. This report analyzed 70 patients among them and excluded the remaining 11 patients whose clinical data could not be found. Their mean age was 25.750.39 years[range 20 \ulcorner50]. The clinical manifestations were cyanosis and clubbing [64 pts], frequent URI[40 pts], anoxic spell [19 pts], infective endo-carditis[4 pts], brain abscess[3 pts], pulmonary tuberculosis[3 pts] and CHF, chest tightness, nephrotic syndrome, left hemiplegia, and tamponade. The types of right ventricular outflow tract obstruction were combined[46 pts], pure infundibular [21 pts] and pure valvular[3 pts]. Associated cardiovascular anomalies were PFO [27 pts], ASDi8 pts], LSVC[8 pts], aortic regurgitation [5 pts], right aortic arch, coronary artery anomalies, PDA and dextrocardia. Hospital mortality was 5.7%. The causes of death ware low cardiac output [2 pts], aggravation of CRF[1 pts] and brain damage[1 pts]. There was one late death because of residual intracardiac shunt and congestive heart failure. During the follow-up period, 16 patients were lost and the remaining 49 patients were asymptomatic and leading normal lives. Residual intracardiac shunt was detected in 5 patients with radionuclide single pass study but all of them had Qp / Qs ratio less than 1.5.

• Journal of Chest Surgery
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• 제19권4호
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• pp.627-632
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• 1986

This report describes our 17-years experience with intracardiac repair in 123 patients older than 15 years with tetralogy of Fallot. Major clinical manifestation was cyanosis and clubbing [102 Pts], but other minor associated manifestation were infective endocarditis, pulmonary tuberculosis, brain abscess, congestive heart failure, nephrotic syndrome, and tuberculous spondylitis. Prior palliative shunts had been performed in 10 patients. Preoperative hemoglobin ranged from 9.7 gm/dl to 25 gm/dl [mean 19 gm/dl]. The type of ventricular septal defect were typical perimembranous type, and total canal defect [13%]. The right ventricular outflow tract obstruction was due to combined [58.5%], infundibular [35%], and valvular stenosis [6.5%]. Transannular patch was used in 17% of patients. Hospital mortality was 9.8% in overall, but decreased to 1.7% since 1982. There was two late death [12 year actuarial survival [97%] due to fulminant hepatitis, residual abnormalities [PS, VSD]. Ninety two percent of survivors at follow-up are asymptomatic and leading an active normal life. Residual ventricular septal defect was detected with radionuclide single pass study in 15.3% of patients but almost cases were Qp/Qs less than 1.5, and only two patients had been candidates for reoperation.

• 한국해안·해양공학회논문집
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• 제34권2호
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• pp.37-45
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• 2022

경사제의 평균 잔류수명을 간편하게 추정할 수 있는 방법을 제시하였다. 누적피해의 시간 이력 자료를 기반으로 하는 추계학적 확률모형과 다르게 내구수명의 분포함수를 이용하여 평균 잔류수명을 추정하는 방법이다. 설계 내구수명과 과거 하중이력에 따라 전문가들이 판단한 내구수명의 상한치와 하한치 그리고 그 발생 가능성을 활용하여 분포함수의 모수도 쉽게 추정할 수 있다. 본 연구에서 제시된 간편법을 전면이 TTP로 피복된 경사제에 적용하였다. TTP 피복재의 시간에 따른 누적피해에 대한 모형실험 자료가 있는 동일 조건에 대하여 WP(Wiener Process) 기반의 추계학적 확률모형도 MCS(Monte-Carlo Simulation) 기법과 함께 적용하였다. 각각의 해석 방법으로부터 얻어진 결과들을 MTTF(Mean Time To Failure)와 함께 비교하여, 실제 발생 가능한 시간에 따른 모든 형태의 피해경로에 대하여 경사제의 내구수명 분포함수는 대수정규분포를 따른다는 것을 알 수 있었다. 마지막으로 본 연구에서 제시된 간편법으로 추정된 경사제의 재령에 따른 평균 잔류수명을 WP 기반 추계학적 확률모형의 결과와 비교하였다. 일정한 재령까지는 누적피해의 증가 형태와 관계없이 비교적 잘 일치하였으나, MTTF 근방의 재령에서는 선형적인 증가와 대수적인 증가 형태에서 어느 정도 차이를 보이고 있다. 따라서 불확실성을 올바로 고려하기 위해서는 추계학적 확률모형을 사용하는 것이 바람직하지만, 본 연구에서 제시한 간편법은 누적피해에 대한 시간 이력 자료를 필요로 하지 않기 때문에 항만 구조물에 대하여 평균 잔류수명 기반의 예방적 유지관리를 신속하게 계획할 필요성이 있는 경우에 유용하게 활용될 수 있다.

• 여성건강간호학회지
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• 제29권2호
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• pp.91-103
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• 2023

Purpose: This study aimed to construct a structural equation model to explain and predict factors affecting the health-related quality of life (QoL) in female rheumatoid arthritis (RA) patients based on the health-related QoL model by Ferrans et al. (2005) and a literature review. Methods: Patients (N=243) who were either registered members of an internet cafe composed of patients with RA or rheumatology outpatients at two tertiary general hospitals in Busan, Korea, were recruited via convenience sampling. Data were collected from July 2 to September 9, 2021, and the survey was conducted using a web-based questionnaire. The data were analyzed by SPSS and AMOS 26.0. Results: The goodness-of-fit statistics of the final model exhibited good results (χ²/degree of freedom=2.68, Turker-Lewis index=.94, comparative fit index=.96, standardized root mean-squared residual=.04, root mean- square error of approximation=.08), and 11 out of 14 paths of the model were supported. The squared multiple correlation, which reflected the explanatory power of the environmental characteristics, symptoms, functional status, and perceived health status on health-related QoL, was 80%. In the hypothesis model, 10 paths had significant direct effects, 6 paths had significant indirect effects, and 12 paths had significant total (direct and indirect) effects. Conclusion: Considering that factors directly affecting the health-related QoL of female patients with RA were social support, symptoms (fatigue and depression), resilience, and perceived health status, and that resilience was the most influential factor, clinicians can encourage resilience. Hence, to improve the health-related QoL of female patients with RA, continuing management is necessary, using various intervention methods that focus on enhancing resilience from the early stage to the end of treatment for RA.

• 농약과학회지
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• 제19권1호
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• pp.14-21
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• 2015

인삼의 재배환경에 따른 잔류특성을 조사하고 살포 농약의 행적을 알아보기 위하여 5년근 인삼포에 덮개 유무와 인삼 줄기의 움직임으로 생긴 구멍을 흙으로 메우는 방법 여부의 서로 다른 조건에서 azoxystrobin (20% SC)을 안전사용기준의 기준량과 배량농도로 수확 7일전까지 10일 간격으로 4회 살포하였으며, 행적 구명 시험을 위해서는 기준량을 1회 살포한 후 분석시료를 채취하였다. 재배기간 중 덮개를 설치하고 구멍을 막은 경우가 잔류량이 낮아 덮개 설치와 구멍 메우기가 잔류량 감소에 기여하는 것으로 판단되었다. 인삼에 살포한 azoxystrobin은 비표면적이 큰 잎에 가장 많이 분포하였으며, 살포시기가 인삼의 수확기에 근접할수록 잎 중 잔류량은 감소하였으나 토양표면의 검출량은 증가하였다. 뇌두를 포함한 인삼 뿌리 중 시험농약의 분포율은 약 0.1%이었으며, 인삼 섭취 시 뇌두를 제거할 경우 12.7-20.4%(평균 16.6%)의 잔류농약 섭취를 감소시키는 효과가 있었다.

• 대한간호학회지
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• 제50권4호
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• pp.554-570
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• 2020

Purpose: This study aimed to develop and test a structural equation model of health-related quality of life among older women following bilateral total knee replacement based on a literature review and Wilson and Cleary's model of health-related quality of life. Methods: One hundred ninety three women who were diagnosed with osteoarthritis, were older than 65 years, and were between 13 weeks and 12 months of having a bilateral total knee replacement were recruited from an outpatient clinic. Data were collected from July 2017 to April 2018 using a structured questionnaire and medical records. Data were analyzed using SPSS/WIN 22.0, AMOS 22.0, and Smart PLS 3.2.4. Results: The fitness of the hypothetical model was good, with coefficients of determination (R²) ranging between .28 and .75 and predictive relevance (Q²) between .26 and .73. The standardized root mean square residual of the model fit indices for the hypothetical model was .04; which explained 64.2% of physical and 62.5% of mental health-related quality of life. Self-efficacy, symptom status, functional status, and general health perceptions had a significant direct effect on physical health-related quality of life, while social support, symptom status, and general health perceptions had a significant direct effect on participants' mental-health-related quality of life. Conclusion: To improve the physical and mental quality of life of older women who receive bilateral knee replacement, nursing-based intervention strategies that reduce symptoms, improve functional status, and increase health perceptions, self-efficacy, and social support are needed. The most important factor is the symptom status.

• Journal of Chest Surgery
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• 제25권1호
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• pp.32-41
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• 1992

From August 1982 to December 1991, 58 consecutive infants with tetralogy of Fallot underwent primary repair. Age ranged from 22 days to twelve months [n=58, 8.7$\pm$2.7 months] and body weight from 3.1 to 13 kilograms [n=58, 7.8$\pm$1.7 kilograms]. Qne infant had absence of the pulmonary valve; one had Ebstein`s anomaly and one had supramitral ring. Thirty-two patients [56%] experienced anoxic spell. Preoperative pulmonary artery indices were measured in 38 cases, ranging 126-552mm2/M2BSA[n=38, 251$\pm$79mm2/M2BSA]. All infants required a right ventricular outflow tract patch; in 41, the patch extended across the pulmonary valve annulus, in 13 of them, monocusps were constructed. All had patch closure of ventricular septal defect. Two infants had REV operation for avoiding injury to the canal branch of the right coronary artery which cross the right ventricular out flow tract. Post repair PRV/LV were measured at operating room in 40 cases, which revealed mean value of 0.49$\pm$0.12 [range: 0.25-0.74]. The hospital mortality was 10.3% [6 patients], and causes of deaths were right heart failure due to sustained right ventricular hypertension[4] and right ventricular outflow tract obstruction, intractablesuraventricular tachyarrhythmia[1], hypoxia[1] due to residual right to left shunt across the atrial septal defect in patient associated with Ebstein`s anomaly. All infants were doing well at follow-up from 1 to 101 months[20.6 months /patient, 1, 072 patient-month] Serial postoperative echocardiograms revealed no residual ventricular septal defects and estimated RVOT gradients between 0 and 40 mmHg except 3 cases [50, 50, 60 mmHg]. There were no late deaths and late ventricular arrhythmias or congestive heart failure. Redo operations were done in 2 cases because of residual right ventricular outflow tract obstruction. This experience with infants with tetralogy of Fallot suggests that, if mortality is tolerable, eletive repair of tetralogy of Fallot could be reasonably undertaken during the first year of life, and even better results could be anticipated along with improvement of methods of myocardial protection and postoperative care.

• Communications for Statistical Applications and Methods
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• 제18권4호
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• pp.485-493
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• 2011

The proportional likelihood ratio order is an extension of the likelihood ratio order for the non-negative absolutely continuous random variables. In addition, the Lindley distribution has been over looked as a mixture of two exponential distributions due to the popularity of the exponential distribution. In this paper, we first recalled the above concepts and then obtained various properties of the Lindley distribution due to the proportional likelihood ratio order. These results are more general than the likelihood ratio ordering aspects related to this distribution. Finally, we discussed the proportional likelihood ratio ordering in view of the weighted version of the Lindley distribution.