• Structural Engineering and Mechanics
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• 제19권3호
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• pp.347-359
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• 2005

This paper attempts to develop the analytical model of estimating the fatigue damage using a linear elastic fracture mechanics method. The stress history on a welding member, when a truck passed over a bridge, was defined as a block loading and the crack closure theory was used. These theories explain the influence of a load on a structure. This study undertook an analysis of the stress range frequency considering both dead load stress and crack opening stress. A probability method applied to stress range frequency distribution and the probability distribution parameters of it was obtained by Maximum likelihood Method and Determinant. Monte Carlo Simulation which generates a probability variants (stress range) output failure block loadings. The probability distribution of failure block loadings was acquired by Maximum likelihood Method and Determinant. This can calculate the fatigue reliability preventing the fatigue failure of a welding member. The failure block loading divided by the average daily truck traffic is a predictive remaining life by a day. Fatigue reliability analysis was carried out for the welding member of the bottom flange of a cross beam and the vertical stiffener of a steel box bridge by the proposed model. Results showed that the primary factor effecting failure time was crack opening stress. It was important to decide the crack opening stress for using the proposed model. Also according to the 50% reliability and 90%, 99.9% failure times were indicated.

• 성인간호학회지
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• 제14권2호
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• pp.184-193
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• 2002

Purpose: The purpose of this study was to assess the characteristics of the user of complementary alternative therapies(CAT) and to identify the important predictive factors associated with them. Method: This study included 142 patients attending outpatient rheumatology clinics of D Hospital in Busan between July and August in 2001. The multiple logistic regression model was developed to estimate the likelihood of user or nonuser of CAT. Result: The duration of illness and chance score of health locus of control were found to be significant factors through the estimated coefficients of using CAT. Duration of illness is longer and chance score of health locus of control is higher in patients who have used CAT in past than that of nonuser. When the model performance was evaluated by comparing the observed outcome with predicted outcome, the model correctly identified 95% of user of CAT and 31% of nonuser. Conclusion: In this survey, duration of illness and chance score of health locus of control are found to be significant factors in predicting utilization of CAT. Nurses who care for rheumatoid arthritis patients should take consideration into health locus of control in planning health education programs.

• 한국지형학회지
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• 제26권2호
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• pp.1-14
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• 2019

This study analyzed the relativity between block stream and talus distributions by employing a likelihood ratio approach. Possible distribution sites for each debris slope landform were extracted by applying a spatial integration model, in which we combined fuzzy set model, Bayesian predictive model, and logistic regression model. Moreover, to verify model performance, a success rate curve was prepared by cross-validation. The results showed that elevation, slope, curvature, topographic wetness index, geology, soil drainage, and soil depth were closely related to the debris slope landform sites. In addition, all spatial integration models displayed an accuracy of over 90%. The accuracy of the distribution potential area map of the block stream was highest in the logistic regression model (93.79%). Eventually, the accuracy of the distribution potential area map of the talus was also highest in the logistic regression model (97.02%). We expect that the present results will provide essential data and propose methodologies to improve the performance of efficient and systematic micro-landform studies. Moreover, our research will potentially help to enhance field research and topographic resource management.

• Journal of Chest Surgery
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• 제57권3호
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• pp.302-311
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• 2024

Background: Unexpected conversion to thoracotomy during planned video-assisted thoracoscopic surgery (VATS) can lead to poor outcomes and comparatively high morbidity. This study was conducted to assess preoperative risk factors associated with unexpected thoracotomy conversion and to develop a risk scoring model for preoperative use, aimed at identifying patients with an elevated risk of conversion. Methods: A retrospective analysis was conducted of 1,506 patients who underwent surgical resection for non-small cell lung cancer. To evaluate the risk factors, univariate analysis and logistic regression were performed. A risk scoring model was established to predict unexpected thoracotomy conversion during VATS of the lung, based on preoperative factors. To validate the model, an additional cohort of 878 patients was analyzed. Results: Among the potentially significant clinical variables, male sex, previous ipsilateral lung surgery, preoperative detection of calcified lymph nodes, and clinical T stage were identified as independent risk factors for unplanned conversion to thoracotomy. A 6-point risk scoring model was developed to predict conversion based on the assessed risk, with patients categorized into 4 groups. The results indicated an area under the receiver operating characteristic curve of 0.747, with a sensitivity of 80.5%, specificity of 56.4%, positive predictive value of 1.8%, and negative predictive value of 91.0%. When applied to the validation cohort, the model exhibited good predictive accuracy. Conclusion: We successfully developed and validated a risk scoring model for preoperative use that can predict the likelihood of unplanned conversion to thoracotomy during VATS of the lung.

• Childhood Kidney Diseases
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• 제12권2호
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• pp.178-185
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• 2008

목 적 : 최근 I, II 등급 방광 요관 역류의 임상적 중요성이 적어지면서 요로감염 영아 모두에게 침습적인 VCUG를 시행하여야 하는지에 대한 의문이 제기되어 있다. 요로감염이 있는 3개월 미만의 영아를 대상으로 III 등급 이상의 중증 방광 요관 역류에 대한 예측인자를 알아보고 VCUG의 시행 여부에 대한 임상적인 근거를 제시하고자 하였다. 방 법: 2004년 1월부터 2007년 9월까지 가천의과대학교 병원에 입원해서 요로감염으로 치료받은 3개월 미만의 환아 중 초음파 검사와 VCUG를 시행받은 환아를 대상으로 하였다. 후향적인 의무기록의 검토를 통하여 I 군(III-V 등급의 방광 요관 역류)과 II 군 (정상 혹은 I, II 등급의 방광 요관 역류) 간의 임상적 지표와 영상 검사 결과를 비교 검토하였다. 초음파의 민감도와 특이도 및 양성예측도와 음성예측도, 그리고 위험도와 우도비를 구하여 중증 방광 요관 역류에 대한 진단적 가치를 알아보았다. 결 과: 총 54명(남아 41명, 여아 13명) 의 대상아 중에서 I군이 14명, II군이 40명이였다. I 군에서 CRP가 높았고(6.11$\pm$5.18와 3.27$\pm$3.45, P=0.025) 비정상적인 초음파 소견이 많았지만(71.4%와 22.5%, P=0.002) 관련 인자를 보정한 후에는 초음파만이 통계적인 유의성이 있었다(P=0.002). 원인균, 균혈증 및 DMSA 이상소견은 두 군간에 유의한 차이가 없었다. 중증 방광 요관 역류에 대한 초음파의 민감도는 71.4%(41.9-91.4), 특이도는 77.5%(61.5-89.1), 위험도는 6.9(1.58-30.41)이었고 음성예측도는 88.6%(73.2-96.7), 음성우도비는 0.37(0.16-0.86)을 나타내었으나($\alpha$=0.05, 검정력 94%) III 등급의 방광 요관 역류4명은(28.6%)은 정상적인 초음파 소견을 보였다. 결 론 : 3개월 미만의 요로감염이 있는 영아에서 중증 방광 요관 역류 에 대해 VCUG를 대체할만한 예측인자를 규명하지 못했다. 따라서 모든 요로감염 영아(3개월 미만)에서 VCUG의 시행이 필요할 것으로 생각된다.

• 대한산업공학회지
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• 제19권2호
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• pp.35-41
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• 1993

Statistical calibration is a useful technique for achieving compatibility between two different measurement methods, and it usually consists of two steps : (1) estimation of the relationship between the standard and nonstandard measurements, and (2) prediction of future standard measurements using the estimated relationship and observed nonstandard measurements. A predictive multivariate errors-in-variables model is presented for the multivariate calibration problem in which the standard as well as the nonstandard measurements are subject to error. For the estimation of the relationship between the two measurements, the maximum likelihood (ML) estimation method is considered. It is shown that the direct and the inverse predictors for the future unknown standard measurement are the same under ML estimation. Based upon large-sample approximations, the mean square error of the predictor is derived.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.622-625
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• 2004

This paper presents multi-source spatial data integration models based on probability theory for landslide hazard assessment. Four probabilistic models such as empirical likelihood ratio estimation, logistic regression, generalized additive and predictive discriminant models are proposed and applied. The models proposed here are theoretically based on statistical relationships between landslide occurrences and input spatial data sets. Those models especially have the advantage of direct use of continuous data without any information loss. A case study from the Gangneung area, Korea was carried out to quantitatively assess those four models and to discuss operational issues.

• 응용통계연구
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• 제21권5호
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• pp.835-843
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• 2008

In this paper, we investigate a Bayesian inference for software reliability models based on mean value functions which take the form of the mixture of beta distribution functions. The posterior simulation via the Markov chain Monte Carlo approach is used to produce estimates of posterior properties. Its applicability is illustrated with two real data sets. We compute the predictive distribution and the marginal likelihood of various models to compare the performance of them. The model comparison results show that the model based on the beta-mixture performs better than other models.

• 전자공학회논문지B
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• 제31B권12호
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• pp.108-115
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• 1994

Most pattern classifiers have been designed based on the ML (Maximum Likelihood) training algorithm which is simple and relatively powerful. The ML training is an efficient algorithm to individually estimate the model parameters of each class under the assumption that all class models in a classifier are statistically independent. That assumption, however, is not valid in many real situations, which degrades the performance of the classifier. In this paper, we propose a minimum-error-rate training algorithm based on the MAP (Maximum a Posteriori) approach. The algorithm regards the normalized outputs of the classifier as estimates of the a posteriori probability, and tries to maximize those estimates. According to Bayes decision theory, the proposed algorithm satisfies the condition of minimum-error-rate classificatin. We apply this algorithm to NPM (Neural Prediction Model) for speech recognition, and derive new disrminative training algorithms. Experimental results on ten Korean digits recognition have shown the reduction of 37.5% of the number of recognition errors.

• Journal of the Korean Data and Information Science Society
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• 제10권1호
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• pp.119-133
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• 1999

마코브체인 몬테칼로 방법을 소프트웨어 신뢰모형에 이용하였다. 베이지안 추론에서 조건부 분포를 가지고 사후분포를 결정하는데 있어서의 계산 문제를 고찰하였다. 특히 레코드값을 통계량을 갖고서 혼합과정과 중첩과정에 대하여 깁스샘플링 알고리즘과 메트로폴리스 알고리즘을 활용하여 베이지안 계산과 모형 선택을 제시하고 모의실험자료를 이용하여 수치적 인 계산을 시행하고 그 결과를 비교하였다.