• Composites Research
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• 제32권5호
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• pp.258-264
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• 2019

본 논문에서는 Hashin 파손 기준식과 crack band 모델이 접목된 손상변수를 이용하여 점진적파손해석 방법이 개발되었다. 파손기준식을 이용하여 파손의 개시 유무가 판단된다. 파손이 개시된 경우에는 각 파손모드(섬유 인장/압축, 기지 인장/압축)에서 손상변수가 선형 열화 거동에 따라 계산되고, 손상강성행렬을 계산하는데 사용된다. 손상강성행렬은 손상된 재료에 반영되고, 계산된 손상강성행렬을 이용하여 재료의 완전한 파괴를 의미하는 손상변수가 1인 시점이 되기까지 점진적 파손해석이 계속해서 반복적으로 수행된다. 일련의 과정들은 상용해석프로그램인 ABAQUS에 사용자 정의 부프로그램을 이용하여 수행되었다. 제안된 점진적파손해석 도구의 검증을 위하여, 원공을 가진 복합재료 적층판의 시험 결과와 비교를 수행하였으며, 시험 중 디지털 이미지 상관법을 이용하여 획득한 변형률 거동과 해석을 통해 획득한 변형률 거동을 비교하였다. 제안된 해석결과는 시험 결과와 비교하여 유효한 일치를 보였다.

• 대한치과교정학회지
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• 제53권6호
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• pp.365-373
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• 2023

Objective: To investigate the potential correlation between fixed orthodontic retention failure and several patient- and treatment-related factors. Methods: Patients finishing treatment with fixed appliances between 2016 and 2017 were retrospectively included in this study. Those not showing fixed retention failure were considered as control group. Patients with fixed retention failure were considered as the experimental group. Additionally, patients with failure of fixed retainers in the period of June 2019 to March 2021 were prospectively identified and included in the experimental group. The location of the first retention failure, sex, pretreatment dental occlusion, facial characteristics, posttreatment dental occlusion, treatment approach and presence of oral habits were compared between groups before and after treatment separately by using a Fisher exact test and a Mann-Whitney U test. Results: 206 patients with fixed retention failure were included, 169 in the mandibular and 74 in the maxillary jaws. Significant correlations were observed between retention failure in the mandibular jaws and mandibular arch length discrepancy (P = 0.010), post-treatment growth pattern (P = 0.041), nail biting (P < 0.001) and abnormal tongue function (P = 0.002). Retention failure in the maxillary jaws was more frequent in patients with IPR in the mandibular jaws (P = 0.005) and abnormal tongue function (P = 0.021). Conclusions: This study suggests a correlation between fixed retention failure and parafunctional habits, such as nail biting and abnormal tongue function. Prospective studies with larger study populations could further confirm these results.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.799-808
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• 2017

Failure of a redundant long-span bridge is often described by innumerable failure modes, which make the structural system reliability analysis become a computationally intractable work. In this paper, an innovative procedure is proposed to efficiently identify the dominant failure modes and quantify the structural reliability for a long-span bridge system. The procedure is programmed by ANSYS and MATLAB. Considering the correlation between failure paths, a new branch and bound operation criteria is applied to the traditional stage critical strength branch and bound algorithm. Computational effort can be saved by ignoring the redundant failure paths as early as possible. The reliability of dominant failure mode is computed by FORM, since the limit state function of failure mode can be expressed by the final stage critical strength. PNET method and FORM for system are suggested to be the suitable calculation method for the bridge system reliability. By applying the procedure to a CFST arch bridge, the proposed method is demonstrated suitable to the system reliability analysis for long-span bridge structure.

• Geomechanics and Engineering
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• 제23권1호
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• pp.51-59
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• 2020

In this paper, the WEKA platform was used to mine and analyze measured data of floor failure depth and a prediction system of floor failure depth was developed with Java. Based on the standardization and discretization of 35-set measured data of floor failure depth in China, the grey correlation degree analysis on five factors affecting the floor failure depth was carried out. The correlation order from big to small is: mining depth, working face length, floor failure resistance, mining thickness, dip angle of coal seams. Naive Bayes model, neural network model and decision tree model were used for learning and training, and the accuracy of the confusion matrix, detailed accuracy and node error rate were analyzed. Finally, artificial neural network was concluded to be the optimal model. Based on Java language, a prediction system of floor failure depth was developed. With the easy operation in the system, the prediction from measured data and error analyses were performed for nine sets of data. The results show that the WEKA prediction formula has the smallest relative error and the best prediction effect. Besides, the applicability of WEKA prediction formula was analyzed. The results show that WEKA prediction has a better applicability under the coal seam mining depth of 110 m~550 m, dip angle of coal seams of 0°~15° and working face length of 30 m~135 m.

• Journal of Pharmaceutical Investigation
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• 제15권3호
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• pp.113-120
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• 1985

The pharmacokinetics of lithium carbonate were investigated in rabbits with folate-induced renal failure. The blood level, the area under the blood concentration curve (AUC) and the biological half·life were increased significantly, and the urinary excretion was decreased significantly compared with those of normal rabbits. Correlation of serum creatinine concentration and AUC, biological half-life, and correlation of creatinine clearance and renal clearance of lithium carbonate have linear relationship respectively. In short, dosage regimen of lithium carbonate is considered to be adjusted in the dose size and the dosing interval by degree of experimental renal failure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.643-650
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• 2002

It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Yunhwajae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. The zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists, would not be relatively affected by the weathering process.

• Journal of Dental Anesthesia and Pain Medicine
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• 제15권3호
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• pp.113-119
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• 2015

Background: The inferior alveolar nerve block (IANB) is the most common anesthetic techniques in dentistry; however, its success rate is low. The purpose of this study was to determine the correlation between IANB failure and mandibular skeletal characteristics Methods: In total, 693 cases of lower third molar extraction (n = 575 patients) were examined in this study. The ratio of the condylar and coronoid distances from the mandibular foramen (condyle-coronoid ratio [CC ratio]) was calculated, and the mandibular skeleton was then classified as normal, retrognathic, or prognathic. The correlation between IANB failure and sex, treatment side, and the CC ratio was assessed. Results: The IANB failure rates for normal, retrognathic, and prognathic mandibles were 7.3%, 14.5%, and 9.5%, respectively, and the failure rate was highest among those with a CC ratio < 0.8 (severe retrognathic mandible). The failure rate was significantly higher in the retrognathic group than in normal group (P = 0.019), and there was no statistically significant difference between the other two groups. Conclusions: IANB failure could be attributable, in part, to the skeletal characteristics of the mandible. In addition, the failure rate was found to be significantly higher in the retrognathic group.

• 한국산학기술학회논문지
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• 제14권8호
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• pp.3665-3671
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• 2013

본 연구는 중학생의 안전실천과 인지실패의 정도를 알아보고, 이 들이 안전사고에 미치는 영향을 알아보기 위한 것이다. 연구대상자는 총 292명이며 2012년 11월 5일부터 11월 25일까지 설문조사하여 자료를 수집하였다. 연구도구는 SPSS win17.0을 사용하였고, 평균과 표준편차, Paired t-test, 피어슨 상관계수를 이용하였다. 대상자의 안전실천과 인지실패는 부(-)의 상관을 나타냈으며 안전에 대한 실천정도가 높은 대상자가 사고인지 실패율이 낮았다. 또한 안전사고 경험이 적게 나타났다. 그와 반대로 안전에 대한 인지실패가 높은 대상자는 안전사고 경험이 높게 나타났다. 따라서 안전실천과 인지실패의 정도를 지속적으로 파악하여 안전사고 예방에 대한 방안을 마련하기 위한 연구가 필요하다. 또한 연구의 범위를 확대함으로써 학교현장에 다양한 안전사고 예방 교육프로그램을 적용하여 안전의식 함양과 안전실천의 일반화가 이루어져야 한다.

• 기본간호학회지
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• 제16권4호
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• pp.490-496
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• 2009

Purpose: The purpose of this study was to examine the validity of a single item scale by comparing a single item scale of health related quality of life to subscopes of the multi-item scales in the Medical Outcome Study Short Form-36 (SF-36), and Minnesota Living with Heart Failure Questionnaire (MLHFQ). Method: The data from 103 patients with heart failure were analyzed. The statistics program SPSS 12.0 used for descriptive statistics. Results: Significant correlations were found between the single item scale and subscopes of SF-36, for physical functioning (r= .42), role physical (r= .22), general health perception (r= .46), vitality (r= .40), social functioning (r= .20) and mental health (r= .51), but not for body pain (r= .12) and role emotional (r= .06). Physical (r= -.41), emotional (r= -.49) and total scores (r= -.49) of MLHFQ were significantly related to the single item scale. Conclusion: The single item scale of health related quality of life showed low to moderate correlation with multi-item scales. Even though the single item scale was correlated with several subscopes of multi-item scales, the correlation was not high, so we have to use caution when using the single item scale instead of multi-item scales.

• Computers and Concrete
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• 제15권4호
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• pp.485-501
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• 2015

Cooling by the flow of water through an embedded cooling pipe has become a common and effective artificial thermal control measure for massive concrete structures. However, an extreme thermal gradient induces significant thermal stress, resulting in thermal cracking. Using a mesoscopic finite-element (FE) mesh, three-phase composites of concrete namely aggregate, mortar matrix and interfacial transition zone (ITZ) are modeled. An equivalent probabilistic model is presented for failure study of concrete by assuming that the material properties conform to the Weibull distribution law. Meanwhile, the correlation coefficient introduced by the statistical method is incorporated into the Weibull distribution formula. Subsequently, a series of numerical analyses are used for investigating the influence of the correlation coefficient on tensile strength and the failure process of concrete based on the equivalent probabilistic model. Finally, as an engineering application, damage and failure behavior of concrete cracks induced by a water-cooling pipe are analyzed in-depth by the presented model. Results show that the random distribution of concrete mechanical parameters and the temperature gradient near water-cooling pipe have a significant influence on the pattern and failure progress of temperature-induced micro-cracking in concrete.