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웨어러블 심전도 측정과 임상 심전도 측정과의 상관관계에 대한 연구
이강휘(Kang-Hwi Lee),이성수(Seong-Su Lee),김상민(Sang-Min Kim),이혁재(Hyeok-Jae Lee),민경진(Kyoung-Jin Min),강현규(Hyun-Kyu Kang),이주현(Joo-Hyeon Lee),곽휘권(Hwy-Kuen Kwak),고윤수(Yun-Soo Ko),이정환(Jeong-Whan Lee) 대한전기학회 2018 전기학회논문지 Vol.67 No.12
Recent advances in ICT technology have transformed many of our daily lives and attracted a lot of attention to personal health. Heart beat measurement that reflects cardiac activities has been used in various fields such as exercise evaluation and psychological state evaluation for a long time, but its utilization method is limited due to its differentiation from clinical electrocardiogram. Therefore, in this study, we could observe the change of the measured signal according to the change of the distance and the position of the measuring electrodes which are non-standard electrode configuration. Based on the electric dipole model of the heart, correlation with clinical electrocardiogram could be confirmed by synthesizing multiple surface potentials measured with a shorter electrode distance than standard one. From the electromagnetic point of view, the distance between the measuring electrodes corresponds to the distance that the electric potential by the cardiac electric dipole moves, and the electric potential measured at the body surface is proportional to the moving distance of the electric potential. Therefore, it is preferable to make the distance between electrodes as long as possible, and to position the measuring electrode close to the ventricle rather than the atrium. In addition, it was found that standard electrocardiographic waveforms could be synthesized by using arithmetic sum of multiple measuring electrodes due to the relationship of electrical dipole vectors, which is obtained by dividing and positioning a plurality of measuring electrodes on a reference electrode line, such as Lead-I, Lead-II direction. Also, we obtained a significant Pearson correlation coefficient (r = 0.9113 ± 0.0169) as a result of synthetic experiments on four subjects.
합성곱 신경망을 이용한 Local Maximum Scalogram 기반 부정맥 분류에 관한 연구
이혁재(Hyeok-Jae Lee),민경진(Kyoung-Jin Min),이상엽(Sang-Yeob Lee),문종민(Jong-Min Moon),이강휘(Kang-Hwi Lee),이정은(Jung-Eun Lee),이정환(Jeong-Whan Lee) 대한전기학회 2021 전기학회논문지 Vol.70 No.5
The purpose of this study is to investigate whether it can be used for arrhythmia detection as a wavelet transform and another feature extraction method using the probability distribution of LMS(Local Maximum Scalogram). The SVM(Support Vector Machine) model uses two kernels: Polynomial and Radial Basis Function(RBF). Three types of data are used: standard deviation of the row (n), standard deviation of the column(n/2), and standard deviation of the row and column (3n/2) of the basic LMS matrix according to the sample (n = 90,180, 270, 360, 450), The training data of the CNN model uses two LMS matrices when fixed to and. The trained model is divided 5 times, and K-fold cross-validation is performed and evaluated using ROC, AUC, and confusion matrix. Finally, the filtered ECG data is compared with the confusion matrix result graph to consider the types of arrhythmia that are difficult to classify. CNN is evaluated to show good overall performance when is. The results of the SVM model show the possibility that the standard deviation values of the LMS’s rows and columns can be used as a feature of arrhythmic bit detection. Since it is simple but very efficient, it is expected to be used in various ways as a single feature extraction method.
Lee, Chang Hyeok,Lim, Hyo Jin,Park, Jae Hyoung,Kim, Jung Hyun,Kim, Jung Soo,Jeong, Min Joon,Song, Min Kyung,Kim, Si Hwan,Hwang, Su Min,Eom, Tae Kang,Lee, Min Jung,Lee, Yang,Ryu, Sung Ju The Kangwon-Kyungki Mathematical Society 2013 한국수학논문집 Vol.21 No.3
We continue the study of power-Armendariz rings over IFP rings, introducing $k$-power Armendariz rings as a generalization of power-Armendariz rings. Han et al. showed that IFP rings are 1-power Armendariz. We prove that IFP rings are 2-power Armendariz. We moreover study a relationship between IFP rings and $k$-power Armendariz rings under a condition related to nilpotency of coefficients.
The Role of CDX2 in Intestinal Metaplasia Evaluated Using Immunohistochemistry
Lee, Byoung Hwan,Kim, Nayoung,Lee, Hye Seung,Kang, Jung Mook,Park, Hyun Kyung,Jo, Hyun Jun,Shin, Cheol Min,Lee, Sang Hyub,Park, Young Soo,Hwang, Jin Hyeok,Kim, Jin-Wook,Jeong, Sook-Hyang,Lee, Dong Ho The Korean Society of Gastroenterology; the Korean 2012 Gut and Liver Vol.6 No.1
<P><B>Background/Aims</B></P><P>Intestinal metaplasia (IM) has been regarded as a premalignant condition. This study evaluated the role of the transforming factor CDX2 according to the severity and type of IM.</P><P><B>Methods</B></P><P>This analysis was performed on 383 subjects with IM in the antrum and/or body, with diagnoses that were categorized as controls, dysplasias, and gastric cancers. The IM grades were classified into four groups as negative, mild, moderate or severe using the updated Sydney scoring system. The IM subtypes were categorized as type I, type II, and type III using high iron diamine and alcian blue (pH 2.5) staining. The CDX2 expression in the IM foci was evaluated using immunohistochemistry in specimens from the antrum and/or body.</P><P><B>Results</B></P><P>CDX2 expression increased according to IM severity (p=0.001) but was not associated with the IM subtype (p=0.881) in the antrum specimens. Similarly, CDX2 expression increased according to the IM grade (p=0.001) but was not associated with the IM subtype (p=0.755) in the body specimens. CDX2 expression was also increased according to baseline disease in the antrum, especially dysplastic and GC group (p=0.003), but not in the body (p=0.582). However, status of <I>Helicobacter pylori</I> infection was not associated with CDX2 expression in the antrum (p=0.692) and body (p=0.271).</P><P><B>Conclusions</B></P><P>These results show that CDX2 expression is associated with the IM grade regardless of the IM subtype and that it was more frequent in the dysplasia group. These results suggest that CDX2 expression might play an important role in the progression of IM in various environments that can affect neoplastic change.</P>
Biopharmaceutical Evaluation of a Solid Dispersion System Containing Sibutramine Freebase
Lee, Min-Suk,Chang, Hee-Chul,Kim, Taewan,Park, Jung-Hwa,Lee, Bong-Sang,Kim, Sung-Hee,Kim, Do-Hwan,Kim, Bo-Gyun,Oh, Seong-Tae,Kang, Myung-Joo,Park, Jong-Hyeok,Lee, Jaehwi,Choi, Young-Wook Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.4
To increase the solubility of sibutramine freebase, the solid dispersion was prepared using a fluid-bed granulator. The solid dispersion containing sibutramine freebase was characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). After filling the sibutramine solid dispersion in the gelatin hard capsule, we performed in vitro dissolution test, the stability test under accelerated conditions and pharmacokinetic study in beagle dogs. The DSC and XRD data showed that sibutramine solid dispersion would be amorphous state. The dissolution rate of sibutramine solid dispersion was significantly increased about 70% than sibutramine freebase. The stability of sibutramine solid dispersion capsules was equivalent or above to commercial product of sibutramine. In beagle dogs, the sibutramine solid dispersion showed equivalent pharmacokinetic behavior with commercial product of sibutramine hydrochloride. In conclusion, the solid dispersion system provided a possible way to overcome the low solubility of sibutramine freebase, and the sibutramine solid dispersion can be a bioequivalent with the commercial product in humans.