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Choi, Kyu Sung,Choi, Seung Hong,Jeong, Bumseok Oxford University Press 2019 Neuro-oncology Vol.21 No.9
<B>Abstract</B><B>Background</B><P>The aim of this study was to predict isocitrate dehydrogenase (IDH) genotypes of gliomas using an interpretable deep learning application for dynamic susceptibility contrast (DSC) perfusion MRI.</P><B>Methods</B><P>Four hundred sixty-three patients with gliomas who underwent preoperative MRI were enrolled in the study. All the patients had immunohistopathologic diagnoses of either IDH-wildtype or IDH-mutant gliomas. Tumor subregions were segmented using a convolutional neural network followed by manual correction. DSC perfusion MRI was performed to obtain T2* susceptibility signal intensity-time curves from each subregion of the tumors: enhancing tumor, non-enhancing tumor, peritumoral edema, and whole tumor. These, with arterial input functions, were fed into a neural network as multidimensional inputs. A convolutional long short-term memory model with an attention mechanism was developed to predict IDH genotypes. Receiver operating characteristics analysis was performed to evaluate the model.</P><B>Results</B><P>The IDH genotype predictions had an accuracy, sensitivity, and specificity of 92.8%, 92.6%, and 93.1%, respectively, in the validation set (area under the curve [AUC], 0.98; 95% confidence interval [CI], 0.969-0.991) and 91.7%, 92.1%, and 91.5%, respectively, in the test set (AUC, 0.95; 95% CI, 0.898-0.982). In temporal feature analysis, T2* susceptibility signal intensity-time curves obtained from DSC perfusion MRI with attention weights demonstrated high attention on the combination of the end of the pre-contrast baseline, up/downslopes of signal drops, and/or post-bolus plateaus for the curves used to predict IDH genotype.</P><B>Conclusions</B><P>We developed an explainable recurrent neural network model based on DSC perfusion MRI to predict IDH genotypes in gliomas.</P>
가변안내깃 설치각이 다단 축류압축기 성능에 미치는 영향
박준영(JunYoung Park),서정민(JeongMin Seo),임형수(HyungSoo Lim),최범석(Bumseok Choi),최태우(Taewoo Choi),최재호(Jaeho Choi) 한국추진공학회 2016 한국추진공학회지 Vol.21 No.1
일반적으로 다단 축류압축기는 부분 부하 조건에서 충분한 운전영역을 확보하기 위해 가변안내깃을 이용한다. 본 연구에서의 해석대상인 다단 축류압축기는 입구에서의 안내깃과 함께 1단과 2단 정익을 가변안내깃으로 하여 운전영역을 확보한다. 따라서 본 연구에서는 정격회전수의 70%와 90% 회전수 조건에서의 가변안내깃의 설치각이 다단 축류압축기의 성능에 미치는 영향에 대해 조사하였다. 다단 축류압축기의 성능은 3차원 정상상태 및 비정상상태 수치해석을 이용하여 확보하였다. 각 해석기법을 통해 확보한 결과를 비교하였으며 내부유동장의 특성을 파악하였다. Generally the variable guide vane is used to secure the sufficient operating point in the off-design condition. In this study the inlet guide vane, 1st and 2nd stators in a multi-stage axial compressor are movable to obtain the operating range. So the effects of variable guide vane setting angle on the performance of 2.5 stage axial compressor were investigated at 70 % and 90 % conditions of nominal rotating speed in this paper. The steady-state and unsteady numerical analyses were conducted at each operating condition. The performance map, lost efficiency and flow fields were compared.
박준영(JunYoung Park),서정민(JeongMin Seo),임형수(HyungSoo Lim),최범석(Bumseok Choi),최태우(Taewoo Choi),최재호(Jaeho Choi) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5
일반적으로 다단 축류압축기는 부분 부하 조건에서 충분한 운전영역을 확보하기 위해 가변정익을 이용한다. 본 연구에서의 해석대상인 다단 축류압축기는 입구에서의 안내깃과 함께 1단과 2단 정익을 가변익으로 하여 운전영역을 확보한다. 따라서 본 연구에서는 정격회전수의 70% 와 90% 회전수 조건에서의 가변정익의 설치각이 다단 축류압축기의 성능에 미치는 영향에 대해 조사하였다. 다단 축류압축기의 성능은 3차원 정상상태 및 비정상상태 수치해석을 이용하여 확보하였다. 각 해석기법을 통해 확보한 결과를 비교하였으며 내부유동장의 특성을 파악하였다. Generally the variable guide vane is used to secure the sufficient operating point in the off-design condition. In this study the inlet guide vane, 1<SUP>st</SUP> and 2<SUP>nd</SUP> stators in a multi-stage axial compressor are movable to obtain the operating range. So the effects of variable guide vane setting angle on the performance of 2.5 stage axial compressor were investigated at 70 % and 90 % conditions of nominal rotating speed in this paper. The steady-state and unsteady numerical analyses were conducted at each operating condition. The performance map lost efficiency and flow fields were compared.
Hairs of discrete symmetries and gravity
Choi, Kang Sin,Kim, Jihn E.,Kyae, Bumseok,Nam, Soonkeon Elsevier 2017 Physics letters: B Vol.769 No.-
<P><B>Abstract</B></P> <P>Gauge symmetries are known to be respected by gravity because gauge charges carry flux lines, but global charges do not carry flux lines and are not conserved by gravitational interaction. For discrete symmetries, they are spontaneously broken in the Universe, forming domain walls. Since the realization of discrete symmetries in the Universe must involve the vacuum expectation values of Higgs fields, a string-like configuration (hair) at the intersection of domain walls in the Higgs vacua can be realized. Therefore, we argue that discrete charges are also respected by gravity.</P>
Weak mixing angle and proton stability in F-theory GUT
Choi, Kang-Sin,Kyae, Bumseok Elsevier 2012 Nuclear physics, B Vol.855 No.1
<P><B>Abstract</B></P><P>It is pointed out that a class of flipped SU(5) models based on F-theory naturally explains the gauge coupling unification. It is because the gauge group SU(5)×U<SUB>(1)X</SUB> is embedded in SO(10) and <SUB>E8</SUB>. To prohibit the dimension 4 and 5 proton decay processes, the structure group associated with monodromy should be SU<SUB>(3)⊥</SUB> or smaller. Extra heavy vector-like pairs of {<SUB>5−2</SUB>,<SUB>5¯2</SUB>} except only one pair of Higgs should be disallowed, because they could induce the unwanted dimension 5 proton decays. We construct a simple global F-theory model considering these points. To maintain <SUP>sin2</SUP>θW0=38 at the GUT scale, the fluxes are turned on only on the flavor branes.</P>
Bumseok Jeong,SangWon Lee,JongSun Lee,JaeHyun Yoo,KoWoon Kim,Sooyun Cho,JeeYoung Ahn,Jeewook Choi 대한신경정신의학회 2015 PSYCHIATRY INVESTIGATION Vol.12 No.2
Objective-The aim of the present study was to examine the psychometric properties of the Korean Verbal Abuse Questionnaire (K-VAQ) that consists of 15 items related with life-time verbal aggression exposure. Methods-A total of 5814 university students who agreed to take part in the study completed the K-VAQ, the Korean version of the Life Event CheckList (LEC-K) and Impact of Event Scale-Revised (K-IES-R). Internal consistency was checked by using item-total item correlation and Cronbach’s alpha coefficient. Exploratory and confirmatory factor analyses were performed, and convergent and concurrent validity levels were examined. Finally, a cluster analysis was conducted to verify the validity of the cutoff point of the K-VAQ. Results-The Cronbach’s alpha correlation coefficient was 0.9. The K-VAQ showed a single factor structure which explained 55.34% of the total variance. The K-VAQ was significantly associated with the LEC-K (r=0.24) and K-IES-R (r=0.28), indicating good convergent validity and concurrent validity. The cluster analysis provided four clusters of trauma experiences: high, moderate, low, and minimal, with K-VAQ ranges of 43–81, 20–42, 7–19, and 0–6, respectively. In a further investigation, a K-VAQ score of 40 was found to be the appropriate cutoff point to delineate the highly verbally abused group, as used in the previous studies. A sum of 36.5% of the highly verbally abused group reported to show substantial symptoms of PTSD (K-IES-R score >22). Conclusion-The present findings suggest that the K-VAQ has good psychometric properties for assessing verbal aggression among the Korean population.
주의력결핍 과잉행동장애 아동에서 틱 장애 동반 여부에 따른 확산 텐서 영상 비교 연구
최지욱,임명호,이창화,박진균,손정우,심세훈,유인규,강현수,정범석 大韓神經精神醫學會 2008 신경정신의학 Vol.47 No.5
Objectives : Diffuse tensor imaging (DTI) was applied to explore the difference in regional distribution and extent of white matter (WM) abnormalities in boys with Attention-deficit/hyperactivity disorder (ADHD) versus boys with comorbid ADHD and tic disorders. Methods : Fifteen boys with ADHD (mean age 9.3 +1.8), 24 ADHD boys with chronic tic disorder or Tourette's disorder(9.9 =b 1.2) and 9 age-, gender-matched controls (9.2 d= 1.8) received DTI assessments. Fractional Anisotropy (FA) maps of WM were compared between groups with a voxel-wise analysis after intersubject registration to MNI space. Results : Bo groups, ADHD group and ADHD with tic disorder group, commonly showed decreased FA than healthy control group in left cerebellar middle peduncle and right frontal lobe, increased FA in right middle occipital WM. In the common areas of left cerebellar middle peduncle and right middle occipital WM, comorbid group showed broader areas of significant FA. The comorbid group also showed increased FA in right cerebellar peduncle, additionally. Conclusion : The findings in ADHD group support previous ADHD hypothesis of the functional abnormalities in corticocerebellar circuit, and suggest that ADHD might have more complicated pathology of neuronal circuit including occipital visual system. The comorbid group showed common areas of overlapping but more extensive abnormalities and also had additional WM abnormalities. ADHD with chronic tic disorders may represent a severe form of ADHD with additional regions of abnormal connectivity.