• 대한간호학회지
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• 제35권1호
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• pp.47-55
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• 2005

Purpose: This study was to evaluate the validity of the Pediatric Index of Mortality Ⅱ(PIM Ⅱ). Method: The first values on PIM Ⅱ variables following ICU admission were collected from the patient's charts of 548 admissions retrospectively in three ICUs(medical, surgical, and neurosurgical) at P University Hospital and a cardiac ICU at D University Hospital in Busan from January 1, 2002 to December 31, 2003. Data was analyzed with the SPSSWIN 10.0 program for the descriptive statistics, correlation coefficient, standardized mortality ratio(SMR), validity index(sensitivity, specificity, positive predictive value, negative predictive value), and AUC of ROC curve. Result: The mortality rate was 10.9% (60 cases) and the predicted death rate was 9.5%. The correlation coefficient(r) between observed and expected death rates was .929(p<.01) and SMR was 1.15. Se, Sp, pPv, nPv, and the correct classification rate were .80, .96, .70, .98, and 94.0% respectively. In addition, areas under the curve (AUC) of the receiver operating characteristic(ROC) was 0.954 (95% CI=0.919～0.989). According to demographic characteristics, mortality was underestimated in the medical group and overestimated in the surgical group. In addition, the AUCs of ROC curve were generally high in all subgroups. Conclusion: The PIM Ⅱ showed a good, so it can be utilized for the subject hospital. better.

• Communications for Statistical Applications and Methods
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• 제16권6호
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• pp.1005-1012
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• 2009

The area under the curve(AUC) is commonly used as a measure of the receiver operating characteristic(ROC) curve which displays the performance of a set of binary classifiers for all feasible ratios of the costs associated with true positive rate(TPR) and false positive rate(FPR). In the bipartite ranking problem where one has to compare two different observations and decide which one is "better", the AUC measures the quantity that ranking score of a randomly chosen sample in one class is larger than that of a randomly chosen sample in the other class and hence, the function which maximizes an AUC of bipartite ranking problem is different to the function which maximizes (minimizes) accuracy (misclassification error rate) of binary classification problem. In this paper, we develop a way to construct the unified framework for AUC maximizer including support vector machines based on maximizing large margin and logistic regression based on estimating posterior probability. Moreover, we develop an efficient algorithm for the proposed unified framework. Numerical results show that the propose unified framework can treat various methodologies successfully.

• 자원환경지질
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• 제46권4호
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• pp.301-312
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• 2013

산사태는 지형, 지질, 임상, 토양 등과 같은 다양한 요인들이 복합적으로 작용하여 발생한다. 따라서 산사태 발생위치와 산사태 유발 요인 사이의 상관관계를 파악할 수 있는 다양한 분석 기법이 사용되고 있으며 본 연구에서는 산사태 위험지역을 정량적으로 예측할 수 있는 효과적인 기법을 제안하고자 퍼지관계 기법과 인공신경망 기법을 이용하여 포항지역의 산사태 취약성을 분석하였다. 취약성 분석을 위해 먼저 산사태 위치를 파악하여 현황도를 작성하였으며, 산사태 발생과 관련 있는 11개의 요인들에 대한 공간 데이터베이스를 구축하였다. 퍼지관계 기법에서는 cosine amplitude method를 이용해 각 요인 별 퍼지 소속 함수 값을 획득하고 퍼지관계 함수 연산을 이용하여 취약성도를 작성하였다. 인공신경망 기법에서는 오류 역전파 알고리즘을 이용하여 산사태와 관련 요인들 간의 상대적 가중치를 결정하고 취약성도를 작성하였다. 두 기법으로 도출된 산사태 취약성도의 ROC(Receiver Operating Characteristic)와 AUC(Area Under the Curve)를 통한 검증 결과는 82.18%와 87.4%로 나타났다. 퍼지 관계 및 인공신경망 기법 모두 높은 예측 정확도를 보여 취약성 분석 기법으로서의 적용 가능성이 있는 것으로 분석되었다. 한편 본 연구지역의 경우 인공신경망 기법이 퍼지관계 기법에 비해 좀 더 나은 예측 정확도를 보이는 것으로 분석되었다.

• Clinical and Experimental Reproductive Medicine
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• 제36권4호
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• pp.255-263
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• 2009

목 적: 한국 가임기 여성의 다낭난소증후군 진단시에 복식 초음파를 이용하는 방법의 유용성과 정확도를 분석하여 국내 다낭난소증후군의 진단 기준 마련에 도움이 되고자 하였다. 연구방법: 이화여자대학교 목동병원에서 선별설문조사를 받은 15~44세 여성 8,793명에서 복식 초음파를 시행한 총 701명 중, 정상 월경을 하면서 안드로겐 과다 및 초음파의 다낭난소 소견이 없는 정상 대조군에서 복식 초음파를 시행한 185명과 초음파 검사 소견을 제외하고 NIH 진단 기준으로 다낭난소증후군을 진단 받은 248명의 환자에서 복식 초음파를 시행한 소견을 ROC (receiver operating characteristic) 곡선 분석하였다. 결 과: 정상 대조군의 평균 연령은 $23.64{\pm}4.26$세로 복식 초음파로 측정된 평균 난소 부피는 $6.03{\pm}1.89\;cm^3$, 평균 난포 개수는 $6.49{\pm}1.93$개였다. 복식 초음파를 진단에 사용할 경우 난소 부피를 이용하면 AURC (area under the ROC curve)가 0.761로 난소 부피>$9\;cm^3$ 기준일 때, 민감도 51.0%, 특이도 91.4%였다. 난포 개수에 대한 AURC는 0.733으로 ${\geq}9$개 기준일 때, 민감도 54.9%, 특이도 87.0%였으며, 난포 개수 ${\geq}10$개 기준일 때, 민감도 53.2%, 특이도 90.4%였다. 복식 초음파로 난소 부피와 난포 개수를 검사하여 다낭난소증후군의 선별 진단에 이용하기에는 부적합하였다. 결 론: 복식 초음파를 이용하여 다낭난소증후군을 진단하는 방법은 유용성과 정확도에서 신뢰할만하지 못하다.

• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1044-1050
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• 2014

Since there is no consensus about the most reliable assays to detect invasive aspergillosis from samples obtained by minimally invasive or noninvasive methods, we compared the efficacy of an enzyme-linked immunosorbent assay (ELISA) for galactomannan (GM) detection and quantitative real-time PCR assay (qRT-PCR) for the diagnosis of invasive pulmonary aspergillosis. Neutropenic, male Sprague-Dawley rats (specific pathogen free; 8 weeks old; weight, $200{\pm}20g$) were immunosuppressed with cyclophosphamide and infected with Aspergillus fumigatus intratracheally. Tissue and whole blood samples were harvested on days 1, 3, 5, and 7 post-infection and examined with GM ELISA and qRT-PCR. The A. fumigatus DNA detection sequence was detected in the following number of samples from 12 immunosuppressed, infected rats examined on the scheduled days: day 1 (0/12), day 3 (0/12), day 5 (6/12), and day 7 (8/12) post-infection. The sensitivity and specificity of the qRT-PCR assay was 29.2% and 100%, respectively. Receiver operating characteristic curve (ROC) analysis indicated a Ct (cycle threshold) cut-off value of 15.35, and the area under the curve (AUC) was 0.627. The GM assay detected antigen in sera obtained on day 1 (5/12), day 3 (9/12), day 5 (12/12), and day 7 (12/12) post-infection, and thus had a sensitivity of 79.2% and a specificity of 100%. The ROC of the GM assay indicated that the optimal Ct cut-off value was 1.40 (AUC, 0.919). The GM assay was more sensitive than the qRT-PCR assay in diagnosing invasive pulmonary aspergillosis in rats.

• 한국융합학회논문지
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• 제13권1호
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• pp.399-408
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• 2022

본 연구에서는 65세 이상 고령자를 대상으로 대사증후군 진단을 위한 지질비율 지표의 유용성을 비교하고자 하였다. 2018년 1월부터 2020년 12월까지 서울지역 종합병원에서 건강검진을 받은 65세 이상 1,464명을 대상으로 하였다. 혈액검사를 통해 혈장 동맥경화 지수를 포함한 지질비율 지표를 측정하였다. 지질비율 지표의 사분위수에 따른 대사증후군 유병률은 로지스틱 회귀분석으로 확인하였다. 또한 수신자 조작 특성(receiver operating characteristic, ROC) 곡선으로 지질비율 지표의 대사증후군 예측능력과 절단값을 추정하였다. 동맥경화 지수와 허리둘레의 상관성이 남녀 모두에서 가장 높았으며(r=0.278, p<0.001 vs r=0.252, p<0.001), 지질비율 지표는 1사분위수와 비교하여 4사분위수에서 대사증후군 발병률이 높았다. 혈장 동맥경화 지수는 다른 지질비율 지표보다 ROC 곡선 아래의 면적(area under the ROC curve; AUC)값이 남녀 각각 0.826(95% CI=0.799-0.850), 0.852(95% CI=0.820-0.881)로 가장 높게 나타났으며, 최적 절단값은 남녀 모두 0.44였다(p<0.001). 따라서 지질비율 지표 중 혈장 동맥경화 지수는 65세 이상 고령자의 대사증후군 진단에 가장 유용한 지표로 나타났다.

• Clinical and Experimental Pediatrics
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• 제60권9호
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• pp.290-295
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• 2017

Purpose: Airway pathology in children with atopic asthma can be reflected by the concave shape of the maximal expiratory flow-volume (MEFV) curve and high fractional exhaled nitric oxide (FeNO) values. We evaluated the capacity of the curvilinearity of the MEFV curve, FeNO, and their combination to distinguish subjects with atopic asthma from healthy individuals. Methods: FeNO and angle ${\beta}$, which characterizes the general configuration of the MEFV curve, were determined in 119 steroid-naïve individuals with atopic asthma aged 8 to 16 years, and in 92 age-matched healthy controls. Receiver operating characteristic (ROC) curve analyses were performed to determine the cutoff points of FeNO and angle ${\beta}$ that provided the best combination of sensitivity and specificity for asthma detection. Results: Asthmatic patients had a significantly smaller angle ${\beta}$ and higher FeNO compared with healthy controls (both, P<0.001). For asthma detection, the best cutoff values of angle ${\beta}$ and FeNO were observed at $189.3^{\circ}$ and 22 parts per billion, respectively. The area under the ROC curve for the combination of angle ${\beta}$ and FeNO improved to 0.91 (95% confidence interval [CI], 0.87-0.95) from 0.80 (95% CI, 0.75-0.86; P<0.001) for angle ${\beta}$ alone and 0.86 (95% CI, 0.82-0.91; P=0.002) for FeNO alone. In addition, the combination enhanced sensitivity with no significant decrease in specificity. Conclusion: These data suggest that the combined use of the curvilinearity of the MEFV curve and FeNO is a useful tool to differentiate between children with and without atopic asthma.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2567-2570
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• 2013

Background: This study analyzed Surveillance, Epidemiology and End Results (SEER) data to assess if socio-economic factors (SEFs) impact on endometrial cancer survival. Materials and Methods: Endometrial cancer patients treated from 2004-2007 were included in this study. SEER cause specific survival (CSS) data were used as end points. The areas under the receiver operating characteristic (ROC) curve were computed for predictors. Time to event data were analyzed with Kaplan-Meier method. Univariate and multivariate analyses were used to identify independent risk factors. Results: This study included 64,710 patients. The mean follow up time (S.D.) was 28.2 (20.8) months. SEER staging (ROC area of 0.81) was the best pretreatment predictor of CSS. Histology, grade, race/ethnicity and county level family income were also significant pretreatment predictors. African American race and low income neighborhoods decreased the CSS by 20% and 3% respectively at 5 years. Conclusions: This study has found significant endometrial survival disparities due to SEFs. Future studies should focus on eliminating socio-economic barriers to good outcomes.

• 전기학회논문지
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• 제67권7호
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• pp.928-933
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• 2018

Nowadays, gastropathy is a common disease. As endoscopic equipment are developed and used widely, it is possible to provide a large number of endoscopy images. Computer-aided Diagnosis (CADx) systems aim at helping physicians to identify possibly malignant abnormalities more accurately. In this paper, we present a CADx system to detect and classify the abnormalities of gastric lesions which include bleeding, ulcer, neuroendocrine tumor and cancer. We used an Inception module based deep learning model. And we used data augmentation for learning. Our preliminary results demonstrated promising potential for automatically labeled region of interest for endoscopy doctors to focus on abnormal lesions for subsequent targeted biopsy, with Az values of Receiver Operating Characteristic(ROC) curve was 0.83. The proposed CADx system showed reliable performance.

• Communications for Statistical Applications and Methods
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• 제25권3호
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• pp.307-319
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• 2018

High-throughput technologies enable the simultaneous evaluation of thousands of genes that could discriminate different subclasses of complex diseases. Ranking genes according to differential expression is an important screening step for follow-up analysis. Many statistical measures have been proposed for this purpose. A good ranked list should provide a stable rank (at least for top-ranked gene), and the top ranked genes should have a high power in differentiating different disease status. However, there is a lack of emphasis in the literature on ranking genes based on these two criteria simultaneously. To achieve the above two criteria simultaneously, we proposed to apply a previously reported metric, the modified area under the receiver operating characteristic cure, to gene ranking. The proposed ranking method is found to be promising in leading to a stable ranking list and good prediction performances of top ranked genes. The findings are illustrated through studies on both synthesized data and real microarray gene expression data. The proposed method is recommended for ranking genes or other biomarkers for high-dimensional omics studies.