• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.275-292
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• 2010

동일 환자에게 적용된 2가지 진단검사의 정확성을 비교하기 위한 방법들 중에서 두개의 ROC곡선 아래 면적(AUC; Area Under Curve)의 차이는 주요한 잣대 중 하나이다. 본 연구에서는 AUC의 차이를 추정하는 방법으로 비모수적방법, 최대가능도법, 일반화추축량에 의한 방법, 붓스트랩방법의 4가지를 포함확률(coverage probability), 기대길이 (expected length) 측면에서 모의실험을 통하여 비교하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권9호
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• pp.4587-4592
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• 2012

Purpose: This study used receiver operating characteristic curve to analyze Surveillance, Epidemiology and End Results (SEER) neuroblastoma (NB) and other peripheral nerve cell tumors (PNCT) outcome data. This study found under usage of radiotherapy in these patients. Materials and methods: This study analyzed socio-economic, staging and treatment factors available in the SEER database for NB and other PNCT. For the risk modeling, each factor was fitted by a generalized linear model to predict the outcome (soft tissue specific death, yes/no). The area under the receiver operating characteristic curve (ROC) was computed. Similar strata were combined to construct the most parsimonious models. A random sampling algorithm was used to estimate the modeling errors. Risk of neuroendocrine (other endocrine including thymus as coded in SEER) death was computed for the predictors. Results: There were 5261 patients diagnosed from 1973 to 2009 were included in this study. The mean follow up time (S.D.) was 83.8 (97.6) months. The mean (SD) age was 18 (25) years. About 30.45% of patients were un-staged. The SEER staging has high ROC (SD) area of 0.58 (0.01) among the factors tested. We simplified the 4-layered risk levels (local, regional, distant, un-staged/others) to a simpler 3-tiered model with comparable ROC area of 0.59 (0.01). Less than 50% of PNCT patients received radiotherapy (RT) including the ones with localized disease. This avoidance of RT use occurred in adults and children. Conclusion: The high under-staging rate may have precented patients from selecting definitive radiotherapy (RT) after surgery. Using RT for, especially, adult PNCT patients is a potential way to improve outcome.

• 한국한의학연구원논문집
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• 제17권2호
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• pp.107-113
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• 2011

Objectives : Sasang typology is extensively studied for the Sasang constitution diagnosis objectification with various data, for example, questionaires, reference materials, etc and analyzed with the several statistical methods. In this study, we used ROC-curve (Receiver Operating Characteristic curve) analysis to diagnose Sasang constitution, which is a kind of epidemiologic research methods and is away from traditional statistical methods. Methods : We collected personality questionnaire which consists of 15 items, from 24 oriental medical clinics. We analyzed the sensitivity and specificity using ROC curve method based on the score of personality questionnaire and also investigated classification accuracy and cut-off value of Sasang constitution. Results : The AUC (area under the ROC curve) value was 0.508 (p=.5511) for Taeeumin, 0.629 (p<.0001) for Soeumin and 0.604(p<.0001) for Soyangin, respectively. so the classification accuracy for Soeumin was highest Soeumin for over 30 points and Soyangin for below 28 points respectively. Conclusions : We suggest that Taeeumin is not classified easily in the ROC-curve analysis. We may classify Soeumin and Soyangin but the accuracy of Sasang constitutional diagnosis is still low.

• 한국의류학회지
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• 제34권3호
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• pp.385-392
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• 2010

The breast types of middle-aged women of 80A (formerly 80B) size were classified through a 3D scanned nude body. Thirty seven measurements including the radius of curvature, surface area, volume, surface length, and breast displacements were used as input variables. We extracted five main factors through the factor analysis of the measurements and classified 36 subjects into 3 clusters through the cluster analysis. As a result of the factor analysis, the size of the breast, breast sag, the curvature of the inner and the outer breast curve, the width of the breast, and the nipple direction were found as the main factors. For the results of the classification of breast types, Cluster 1 was characterized by narrow breast width and unsymmetrical under the breast curve, whereas Cluster 2 was a wide and sagged shape. Cluster 3 was classified into big breast volume and symmetrical under-breast curve. The results are useful to the product development of high quality brassieres which reflect the 3D characteristics of breast types of middle-aged women.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권1호
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• pp.1-7
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• 2021

Air-water interfacial area is of great importance for the analysis of contaminant mass transfer processes occurring in the soil systems. Capillary bundle model has been proposed to estimate the specific air-water interfacial areas in unsaturated soils. In this study, the measured air-water interfacial areas of a soil (loam) using the gaseous interfacial tracer technique were compared to those from capillary bundle model. The measured values converged to the specific solid surface area (7.6×104 ㎠/㎤) of the soil. However, the simulated air-water interfacial areas based on the capillary bundle model deviated significantly from those measured. The simulated values were substantially over-estimated at low end of the water content range, whereas the model under-estimated the air-water interfacial area for the most of the water content range. This under-estimation is considered to be caused by the nature of the capillary bundle model that replaces the soil pores with a bundle of glass capillaries and thus no surface roughness at the inner surface of the capillaries is taken into account for the estimation of the air-water interfacial area with the capillary bundle model. Subsequently, appropriate correction is necessary for the capillary bundle model to estimate the air-water interfacial area in soils. Since the soil-moisture release curve data is the basis of the capillary bundle model, the model can be of use due to its simplicity, while the gaseous tracer technique requires complicated experimental equipment followed by moment analysis of the breakthrough curves. The size distribution profile of the pores filled with gas estimated by the water retention curve was found to be similar to that of particle size at different size range. The shifted distribution of gas-filled pores toward smaller size side compared to the particle size distribution was also found.

• 한국콘텐츠학회논문지
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• 제11권10호
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• pp.342-348
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• 2011

생체 간이식 공여자를 대상으로 시행되는 간생검 조직소견의 지방변성 정도와 복부초음파검사 결과를 분석하여, 지방간 질환의 진단에 있어서 초음파검사의 타당성을 알아보고자 하였다. 총 지방 함유량 10% 기준으로 범주화 하여 10% 이하를 음성, 10% 이상을 양성으로 하였을 때 초음파검사의 민감도는 64.6%이었고, 특이도는 68% 이었으며, 양성 예측도와 음성 예측도는 각각 76.8%, 54% 이었다. 초음파검사 결과 정상과 경증을 음성으로, 중등도를 양성으로 조작하였을 때 초음파검사의 민감도는 26.8% 이었고, 특이도는 100% 이었으며, 양성 예측도와 음성 예측도는 각각 100%, 45.5% 이었다. 총 지방 함유량 10% 이상을 상태변수(State variable)로 ROC curve 분석을 시행 하였을 때. 간/신장 명도비의 곡선하면적(Area under curve, AUC)은 0.859로 지방간을 예측하는데 좋은 지표로 나타났으며, 95% 신뢰구간(CI: 0.795~0.922)이 통계적으로 유의한 값을 보였다(p<0.001). 지방간진단에 있어서 복부초음파검사는 간생검 병리학적 결과를 예측하는데 높은 타당도를 보였다.

• 대한통합의학회지
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• 제10권3호
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• pp.107-117
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• 2022

Purpose : The purpose of this study was to establish a model of the predictive factors for success or failure of examinees undertaking the Korean physical therapist licensing examination (KPTLE). Additionally, we assessed the pass/fail cut-off point. Methods : We analyzed the results of 10,881 examinees who undertook the KPTLE, using data provided by the Korea Health Personnel Licensing Examination Institute. The target variable was the test result (pass or fail), and the input variables were: sex, age, test subject, and total score. Frequency analysis, chi-square test, descriptive statistics, independent t-test, correlation analysis, binary logistic regression, and receiver operating characteristic (ROC) curve analyses were performed on the data. Results : Sex and age were not significant predictors of attaining a pass (p>.05). The test subjects with the highest probability of passing were, in order, medical regulation (MR) (Odds ratio (OR)=2.91, p<.001), foundations of physical therapy (FPT) (OR=2.86, p<.001), diagnosis and evaluation for physical therapy (DEPT) (OR=2.74, p<.001), physical therapy intervention (PTI) (OR=2.66, p<.001), and practical examination (PE) (OR=1.24, p<.001). The cut-off points for each subject were: FPT, 32.50; DEPT, 29.50; PTI, 44.50; MR, 14.50; and PE, 50.50. The total score (TS) was 164.50. The sensitivity, specificity, and the classification accuracy of the prediction model was 99 %, 98 %, and 99 %, respectively, indicating high accuracy. Area under the curve (AUC) values for each subject were: FPT, .958; DEPT, .968; PTI, .984; MR, .885; PE, .962; and TS, .998, indicating a high degree of fit. Conclusion : In our study, the predictive factors for passing KPTLE were identified, and the optimal cut-off point was calculated for each subject. Logistic regression was adequate to explain the predictive model. These results will provide universities and examinees with useful information for predicting their success or failure in the KPTLE.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.867-870
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• 2014

Purpose: This study used receiver operating characteristic curve to analyze Surveillance, Epidemiology and End Results (SEER) ependymoma data to identify predictive models and potential disparity in outcome. Materials and Methods: This study analyzed socio-economic, staging and treatment factors available in the SEER database for ependymoma. For the risk modeling, each factor was fitted by a Generalized Linear Model to predict the outcome ('brain and other nervous systems' specific death in yes/no). The area under the receiver operating characteristic curve (ROC) was computed. Similar strata were combined to construct the most parsimonious models. A random sampling algorithm was used to estimate the modeling errors. Risk of ependymoma death was computed for the predictors for comparison. Results: A total of 3,500 patients diagnosed from 1973 to 2009 were included in this study. The mean follow up time (S.D.) was 79.8 (82.3) months. Some 46% of the patients were female. The mean (S.D.) age was 34.4 (22.8) years. Age was the most predictive factor of outcome. Unknown grade demonstrated a 15% risk of cause specific death compared to 9% for grades I and II, and 36% for grades III and IV. A 5-tiered grade model (with a ROC area 0.48) was optimized to a 3-tiered model (with ROC area of 0.53). This ROC area tied for the second with that for surgery. African-American patients had 21.5% risk of death compared with 16.6% for the others. Some 72.7% of patient who did not get RT had cerebellar or spinal ependymoma. Patients undergoing surgery had 16.3% risk of death, as compared to 23.7% among those who did not have surgery. Conclusion: Grading ependymoma may dramatically improve modeling of data. RT is under used for cerebellum and spinal cord ependymoma and it may be a potential way to improve outcome.

• 한국해양공학회지
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• 제6권2호
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• pp.35-40
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• 1992

A recently developed new technique for measuring the fraction of wetted area has applied to pool boiling of water. The basis of the new applied technique of ultrasonic makes use of the reflection of ultrasonic from the vapour surface to measure the fraction of wetted area values. The results are the measured fraction of wetted area values in nucleate and transition boiling and the pool boiling curve for water under steady state conditions. The measurement of this paper shows a fraction of wetted areaf around 0.98 at the critical heat flux for water.

• Nuclear Medicine and Molecular Imaging
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• 제41권3호
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• pp.201-208
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• 2007

목적: 유방암의 감별진단에서 기존의 유방 초음파 검사나 핵의학 유방SPECT의 진단성능에는 한계가 있다. 저자들은 초음파 컴퓨터진단시스템(CAD: computer aided diagnosis)의 적용에 의하여 유방 SPECT의 진단성능이 향상되는지를 알아보았다. 대상 및 방법: 유방초음파 및 유방 SPECT(Tc-99m tetrofosmin)를 시행하고 수술후 확진된 여자환자 40명(21명:악성종양, 19명:양성병변)의 영상자료를 분석하였다. 유방초음파영상을 컴퓨터분석 소프트웨어를 이용하여 병변의 경계를 분리한 후, 영상의 형태학적 특성들을 추출하였다. 초음파영상에서 추출된 형태학적 특성 중에서 감별능력이 있는 것으로 판단된 특성들을 골라 정량화하였다. 정량화된 형태학적 특성값들을 유방SPECT에서 구한 병변 대 반대측 유방의 방사능비와 판별분석에 의하여 결합하여 새로운 파라메터인 D-수치를 산출하였다. 유방SPECT의 병변 방사능비, 유방초음파 컴퓨터진단시스템의 악성확률 및 두가지를 결합한 D-수치에 대하여 수신자판단특성곡선(ROC curve) 분석을 이용하여 최적 판별 수치(cut-off value)를 구하고 이에 의한 유방암 진단의 예민도, 특이도 및 정확도를 계산하여 유방 SPECT과 초음파 컴퓨터진단시스템의 결합에 의한 진단성능을 기존의 유방 SPECT의 진단성능과 비교하였다. 결과: ROC curve분석상에서 유방암 진단에 대한 성능은 유방초음파의 컴퓨터 분석시스템 및 유방SPECT 각각 모두 우수하였다(area under curve=0.831 and 0.846). 두 결과를 통계적인 방법으로 결합하였을 때 ROC curve분석의 area under curve는(0.860) 향상되었으나, 최적 판별 수치(cut-off value)에 의한 유방암 진단의 예민도, 특이도 및 정확도에는 통계적인 차이는 없었다. 결론: 유방초음파의 컴퓨터분석시스템의 결과를 유방 SPECT에 적용하여 유방암의 진단성능을 향상시킬 수 있었지만 통계적으로는 유의하지 못하였다. 향후 추가적인 연구가 필요할 것으로 보인다.