• Korean Journal of Radiology
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• v.22 no.9
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• pp.1579-1586
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• 2021

Objective: To evaluate the diagnostic performance of the modified Korean Thyroid Imaging Reporting and Data System (K-TIRADS), and compare it with the 2016 version of K-TIRADS using the Thyroid Imaging Network of Korea. Materials and Methods: Between June and September 2015, 5708 thyroid nodules (≥ 1.0 cm) from 5081 consecutive patients who had undergone thyroid ultrasonography at 26 institutions were retrospectively evaluated. We used a biopsy size threshold of 2 cm for K-TIRADS 3 and 1 cm for K-TIRADS 4 (modified K-TIRADS 1) or 1.5 cm for K-TIRADS 4 (modified K-TIRADS 3). The modified K-TIRADS 2 subcategorized the K-TIRADS 4 into 4A and 4B, and the cutoff sizes for the biopsies were defined as 1 cm for K-TIRADS 4B and 1.5 cm for K-TIRADS 4A. The diagnostic performance and the rate of unnecessary biopsies of the modified K-TIRADS for detecting malignancy were compared with those of the 2016 K-TIRAD, which were stratified by nodule size (with a threshold of 2 cm). Results: A total of 1111 malignant nodules and 4597 benign nodules were included. The sensitivity, specificity, and unnecessary biopsy rate of the benign nodules were 94.9%, 24.4%, and 60.9% for the 2016 K-TIRADS; 91.0%, 39.7%, and 48.6% for the modified K-TIRADS 1; 84.9%, 45.9%, and 43.5% for the modified K-TIRADS 2; and 76.1%, 50.2%, and 40.1% for the modified K-TIRADS 3. For small nodules (1-2 cm), the diagnostic sensitivity of the modified K-TIRADS decreased by 5.2-25.6% and the rate of unnecessary biopsies reduced by 19.2-32.8% compared with those of the 2016 K-TIRADS (p < 0.001). For large nodules (> 2 cm), the modified K-TIRADSs maintained a very high sensitivity for detecting malignancy (98%). Conclusion: The modified K-TIRADSs significantly reduced the rate of unnecessary biopsies for small (1-2 cm) nodules while maintaining a very high sensitivity for malignancy for large (> 2 cm) nodules.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.364-367
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• 2008

This present paper describes concepts of the real-time operation monitoring system as a tool for enhancing the reliability and raising the availability of the first Korea IGCC (Integrated Gasification Combined Cycle) power plant. This system consists of five (5) modules : (1) Data Validation Module, (2) Performance Calculation Module (3) Performance Diagnostic Module, (4) Trip Information Module, and (5) Statistics Analysis Module. Among these modules, Performance Calculation Module is explained in more detail. The objective of this module is to continuously evaluate the degradation (decrease in performance) of the IGCC plant and its equipment in order to provide plant operators additional information to help them identify problems, improve performance.

• Clinical and Experimental Pediatrics
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• v.56 no.2
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• pp.45-51
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• 2013

Because nonalcoholic steatohepatitis can progress towards cirrhosis even in children, early detection of hepatic fibrosis and accurate diagnosis of nonalcoholic fatty liver disease (NAFLD) are important. Although liver biopsy is regarded as the gold standard of diagnosis, its clinical application is somewhat limited in children due to its invasiveness. Noninvasive diagnostic methods, including imaging studies, biomarkers of inflammation, oxidative stress, hepatic apoptosis, hepatic fibrosis, and noninvasive hepatic fibrosis scores have recently been developed for diagnosing the spectrum of NAFLD, particularly the severity of hepatic fibrosis. Although data and validation are still lacking for these noninvasive modalities in the pediatric population, these methods may be applicable for pediatric NAFLD. Therefore, noninvasive imaging studies, biomarkers, and hepatic fibrosis scoring systems may be useful in the detection of hepatic steatosis and the prediction of hepatic fibrosis, even in children with NAFLD.

• Progress in Medical Physics
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• v.30 no.2
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• pp.39-48
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• 2019

Deep learning has been applied to various medical data. In particular, current deep learning models exhibit remarkable performance at specific tasks, sometimes offering higher accuracy than that of experts for discriminating specific diseases from medical images. The current status of deep learning applications to molecular imaging can be divided into a few subtypes in terms of their purposes: differential diagnostic classification, enhancement of image acquisition, and image-based quantification. As functional and pathophysiologic information is key to molecular imaging, this review will emphasize the need for accurate biomarker acquisition by deep learning in molecular imaging. Furthermore, this review addresses practical issues that include clinical validation, data distribution, labeling issues, and harmonization to achieve clinically feasible deep learning models. Eventually, deep learning will enhance the role of theranostics, which aims at precision targeting of pathophysiology by maximizing molecular imaging functional information.

• The Pure and Applied Mathematics
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• v.27 no.2
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• pp.71-81
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• 2020

Multicollinearity is a common problem in linear regression models when two or more regressors are highly correlated, which yields some serious problems for the ordinary least square estimates of the parameters as well as model validation and interpretation. In this paper, first the problem of multicollinearity and its subsequent effects on the linear regression along with some important measures for detecting multicollinearity is reviewed, then the role of eigenvalues and eigenvectors in detecting multicollinearity are bolded. At the end a real data set is evaluated for which the fitted linear regression models is investigated for multicollinearity diagnostics.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.10 no.2
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• pp.67-78
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• 2006

Objectives : To review the method, validity and reliability of Impedance Cardiography and to study its oriental medical application. Method : The papers reviewed in this study were searched through internet search engines such as Springer, Science Direct, and China National Knowledge Infrastructure. Conclusion : In this study, the methodological limitations, validity and reliability of impedance cardiography were examined. Impedance Cardiography is recognized as a highly accurate non-invasive tool to assess hemodynamic parameters. The ability of impedance cardiography to assess hemodynamic parameters in non-invasive way is very suitable for researches on the effect of oriental medical therapeutics or the validation of oriental medical diagnostic.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.2
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• pp.98-103
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• 2015

Good manufacturing Practice (GMP) regulation for diagnostic and therapeutic radiopharmaceuticals was prepared at 2014. The mandatory GMP regulation becomes effective on $1^{st}$, July 2015,with two years of grace periods. Korean radiopharmaceuticals GMP regulation was consisted of quality management, personnel, premise and facility, documentation, production, quality control and self-audit and they have a very similar structure to European Union and PIC/S GMP regulation. Here, we describe detailed description of GMP regulation each part and application to radiopharmaceuticals production. And we also compare Korea, Japan and USA radiopharmaceuticals GMP regulation. GMP is a method to maintain quality of radiopharmaceuticals in daily production and it must be embedded on the manufacturing operation and management.

• Korean Journal of Radiology
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• v.23 no.4
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• pp.466-478
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• 2022

Objective: ¹⁸F-fluorodeoxyglucose (FDG) PET/CT is often used for detecting malignancy in patients with newly diagnosed hemophagocytic lymphohistiocytosis (HLH), with acceptable sensitivity but relatively low specificity. The aim of this study was to improve the diagnostic ability of ¹⁸F-FDG PET/CT in identifying malignancy in patients with HLH by combining ¹⁸F-FDG PET/CT and clinical parameters. Materials and Methods: Ninety-seven patients (age ≥ 14 years) with secondary HLH were retrospectively reviewed and divided into the derivation (n = 71) and validation (n = 26) cohorts according to admission time. In the derivation cohort, 22 patients had malignancy-associated HLH (M-HLH) and 49 patients had non-malignancy-associated HLH (NM-HLH). Data on pretreatment ¹⁸F-FDG PET/CT and laboratory results were collected. The variables were analyzed using the Mann-Whitney U test or Pearson's chi-square test, and a nomogram for predicting M-HLH was constructed using multivariable binary logistic regression. The predictors were also ranked using decision-tree analysis. The nomogram and decision tree were validated in the validation cohort (10 patients with M-HLH and 16 patients with NM-HLH). Results: The ratio of the maximal standardized uptake value (SUVmax) of the lymph nodes to that of the mediastinum, the ratio of the SUVmax of bone lesions or bone marrow to that of the mediastinum, and age were selected for constructing the model. The nomogram showed good performance in predicting M-HLH in the validation cohort, with an area under the receiver operating characteristic curve of 0.875 (95% confidence interval, 0.686-0.971). At an appropriate cutoff value, the sensitivity and specificity for identifying M-HLH were 90% (9/10) and 68.8% (11/16), respectively. The decision tree integrating the same variables showed 70% (7/10) sensitivity and 93.8% (15/16) specificity for identifying M-HLH. In comparison, visual analysis of ¹⁸F-FDG PET/CT images demonstrated 100% (10/10) sensitivity and 12.5% (2/16) specificity. Conclusion: ¹⁸F-FDG PET/CT may be a practical technique for identifying M-HLH. The model constructed using ¹⁸F-FDG PET/CT features and age was able to detect malignancy with better accuracy than visual analysis of ¹⁸F-FDG PET/CT images.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1124-1139
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• 2021

The objective assessment of atrophy and the measurement of brain volume is important in the early diagnosis of dementia and neurodegenerative diseases. Recently, several MR-based volumetry software have been developed. For their clinical application, several issues arise, including the standardization of image acquisition and their validation of software. Additionally, it is important to highlight the diagnostic performance of the volumetry software based on expert opinions. We instituted a task force within the Korean Society of Neuroradiology to develop guidelines for the clinical use of MR-based brain volumetry software. In this review, we introduce the commercially available software and compare their diagnostic performances. We suggest the need for a standard protocol for image acquisition, the validation of the software, and evaluations of the limitations of the software related to clinical practice. We present recommendations for the clinical applications of commercially available software for volumetry based on the expert opinions of the Korean Society of Neuroradiology.

• Anxiety and mood
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• v.2 no.1
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• pp.50-55
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• 2006

Objectives : In the psychiatry, structured interview is very important tool to be used in epidemiological or psychopharmacological studies. However, investigators often find that the administration of comprehensive diagnostic interviews is time-consuming and expensive to be used in clinical or research settings. Considering these points, Sheehan and his colleagues developed MINI (Mini International Neuropsychiatric Interview) to meet the need for a brief, reliable, and valid structured diagnostic interview for psychiatric disorders. The MINI has been translated into many languages and used in many countries. Therefore, we translated the MINI into Korean and determined its validity in this study. Methods : Twohundred seventy patients and normal subjects participated in the validation of the MINI versus an expert's professional opinion. Schizophrenia and other psychotic disorders, mood disorders including major depressive disorder and bipolar disorder, anxiety disorders including panic and other phobic disorders, and alcohol dependence were included in this study. The validity was obtained by examination whether MINI based diagnoses were compatible with diagnoses by expert psychiatrists. Results : The range of Kappa values was 0.22 (somatoform disorder) to 0.93 (bipolar disorder - past). Overall agreement between MINI and expert's diagnoses were good. The Kappa values for anxiety disorders seemed to be higher than those for other disorders. Conclusion : The MINI Korean version has the good validity. It also has potential applications as a diagnostic tool for psychiatric disorders.