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Variance components for two-way nested design data
Choi, Jaesung The Korean Statistical Society 2018 Communications for statistical applications and me Vol.25 No.3
This paper discusses the use of projections for the sums of squares in the analyses of variance for two-way nested design data. The model for this data is assumed to only have random effects. Two different sizes of experimental units are required for a given experimental situation, since nesting is assumed to occur both in the treatment structure and in the design structure. So, variance components are coming from the sources of random effects of treatment factors and error terms in different sizes of experimental units. The model for this type of experimental situation is a random effects model with more than one error terms and therefore estimation of variance components are concerned. A projection method is used for the calculation of sums of squares due to random components. Squared distances of projections instead of using the usual reductions in sums of squares that show how to use projections to estimate the variance components associated with the random components in the assumed model. Expectations of quadratic forms are obtained by the Hartley's synthesis as a means of calculation.
The Impact of Shadow Education on Mainstream Education
Jaesung Choi(최재성),Soo-yong Byun(변수용) 한국고용노사관계학회 2015 한국노사관계학회 학술대회 Vol.2015 No.동계
In this study, we investigate how shadow education shapes teaching and learning processes in the mainstream educational system. In particular, we are interested in studying how the degree to which students participate in shadow education within a school affects teachers’ job satisfaction, attitudes toward students, and efforts to prepare for their class. Using recent four waves of the Analysis on the Level of School Education and Its Actual Status of Korean Schools for elementary and middle schools, we found that an increasing share of students participating in shadow education within a school had a negative impact on teachers’ effort and motivation at school. This suggests an important channel by which shadow education would have a negative consequence on the disadvantaged students who have a limited access to shadow education, which would widen educational inequality, especially in academic achievement.
Nonnegative variance component estimation for mixed-effects models
Choi, Jaesung The Korean Statistical Society 2020 Communications for statistical applications and me Vol.27 No.5
This paper suggests three available methods for finding nonnegative estimates of variance components of the random effects in mixed models. The three proposed methods based on the concepts of projections are called projection method I, II, and III. Each method derives sums of squares uniquely based on its own method of projections. All the sums of squares in quadratic forms are calculated as the squared lengths of projections of an observation vector; therefore, there is discussion on the decomposition of the observation vector into the sum of orthogonal projections for establishing a projection model. The projection model in matrix form is constructed by ascertaining the orthogonal projections defined on vector subspaces. Nonnegative estimates are then obtained by the projection model where all the coefficient matrices of the effects in the model are orthogonal to each other. Each method provides its own system of linear equations in a different way for the estimation of variance components; however, the estimates are given as the same regardless of the methods, whichever is used. Hartley's synthesis is used as a method for finding the coefficients of variance components.
Jaesung Choi,Jee-Hye Choi,Ho Woon Lee,Dongbeom Seo,Gavaachimed Lkhagvasuren,Jung-Woong Kim,Sang-Beom Seo,Kangseok Lee,Kwang-Ho Lee 생화학분자생물학회 2023 BMB Reports Vol.56 No.2
Karyopherin-α3 (KPNA3), a karyopherin- α isoform, is intimatelyassociated with metastatic progression via epithelial-mesenchymaltransition (EMT). However, the molecular mechanismunderlying how KPNA3 acts as an EMT inducer remains to beelucidated. In this report, we identified that KPNA3 was significantlyupregulated in cancer cells, particularly in triple-negativebreast cancer, and its knockdown resulted in the suppressionof cell proliferation and metastasis. The comprehensivetranscriptome analysis from KPNA3 knockdown cells indicatedthat KPNA3 is involved in the regulation of numerous EMTrelatedgenes, including the downregulation of GATA3 andE-cadherin and the up-regulation of HAS2. Moreover, it wasfound that KPNA3 EMT-mediated metastasis can be achievedby TGF-β or AKT signaling pathways; this suggests that thenovel independent signaling pathways KPNA3-TGF-β-GATA3-HAS2/E-cadherin and KPNA3-AKT-HAS2/E-cadherin are involvedin the EMT-mediated progress of TNBC MDA-MB-231 cells. These findings provide new insights into the divergent EMTinducibility of KPNA3 according to cell and cancer type.
Inhibition of Wntless/GPR177 suppresses gastric tumorigenesis
( Jaesung Seo ),( Hyun Jung Kee ),( Hye Ji Choi ),( Jae Eun Lee ),( Soo-yeon Park ),( Seung-hyun Lee ),( Mi-hyeon Jeong ),( Garam Guk ),( Sooyeon Lee ),( Kyung-chul Choi ),( Yoon Young Choi ),( Hyunki 생화학분자생물학회(구 한국생화학분자생물학회) 2018 BMB Reports Vol.51 No.5
Wntless/GPR177 functions as WNT ligand carrier protein and activator of WNT/β-catenin signaling, however, its molecular role in gastric cancer (GC) has remained elusive. We investigated the role of GPR177 in gastric tumorigenesis and provided the therapeutic potential of a clinical development of anti-GPR177 monoclonal antibodies. GPR177 mRNA expression was assessed in GC transcriptome data sets (GSE15459, n = 184; GSE66229, n = 300); protein expression was assessed in independent patient tumor tissues (Yonsei TMA, n = 909). GPR177 expression were associated with unfavorable prognosis [log-rank test, GSE15459 (P = 0.00736), GSE66229 (P = 0.0142), and Yonsei TMA (P = 0.0334)] and identified as an independent risk predictor of clinical outcomes: GSE15459 [hazard ratio (HR) 1.731 (95% confidence interval; CI; 1.103- 2.715), P = 0.017], GSE66229 [HR 1.54 (95% CI, 1.10-2.151), P = 0.011], and Yonsei TMA [HR 1.254 (95% CI, 1.049- 1.500), P = 0.013]. Either antibody treatment or GPR177 knockdown suppressed proliferation of GC cells and sensitized cells to apoptosis. And also inhibition of GPR177 suppresses in vitro and in vivo tumorogenesis in GC cells and inhibits WNT/β-catenin signaling. Finally, targeting and inhibition of GPR177 with antibody suppressed tumorigenesis in PDX model. Together, these results suggest GPR177 as a novel candidate for prognostic marker as well as a promising target for treatment of GC patients. [BMB Reports 2018; 51(5): 255-260]
Nonnegative estimates of variance components in a two-way random model
Choi, Jaesung The Korean Statistical Society 2019 Communications for statistical applications and me Vol.26 No.4
This paper discusses a method for obtaining nonnegative estimates for variance components in a random effects model. A variance component should be positive by definition. Nevertheless, estimates of variance components are sometimes given as negative values, which is not desirable. The proposed method is based on two basic ideas. One is the identification of the orthogonal vector subspaces according to factors and the other is to ascertain the projection in each orthogonal vector subspace. Hence, an observation vector can be denoted by the sum of projections. The method suggested here always produces nonnegative estimates using projections. Hartley's synthesis is used for the calculation of expected values of quadratic forms. It also discusses how to set up a residual model for each projection.
Multi-Finger 3D Landmark Detection using Bi-Directional Hierarchical Regression
Choi, Jaesung,Lee, Minkyu,Lee, Sangyoun International Society for Simulation Surgery 2016 Journal of International Society for Simulation Su Vol.3 No.1
Purpose In this paper we proposed bi-directional hierarchical regression for accurate human finger landmark detection with only using depth information.Materials and Methods Our algorithm consisted of two different step, initialization and landmark estimation. To detect initial landmark, we used difference of random pixel pair as the feature descriptor. After initialization, 16 landmarks were estimated using cascaded regression methods. To improve accuracy and stability, we proposed bi-directional hierarchical structure.Results In our experiments, the ICVL database were used for evaluation. According to our experimental results, accuracy and stability increased when applying bi-directional hierarchical regression more than typical method on the test set. Especially, errors of each finger tips of hierarchical case significantly decreased more than other methods.Conclusion Our results proved that our proposed method improved accuracy and stability and also could be applied to a large range of applications such as augmented reality and simulation surgery.
Choi, Jaesung,Choi, Ji-Yeob,Shin, Aesun,Lee, Sang-Ah,Lee, Kyoung-Mu,Oh, Juhwan,Park, Joo Yong,Lee, Jong-koo,Kang, Daehee Japan Epidemiological Association 2019 Journal of epidemiology Vol.29 No.4
<P><B>Background</B></P><P>We aimed to report the prevalence and correlates of high-risk alcohol consumption and types of alcoholic beverages.</P><P><B>Methods</B></P><P>The baseline data of the Health Examinees-Gem (HEXA-G) study participants, including 43,927 men and 85,897 women enrolled from 2005 through 2013, were used for analysis. Joinpoint regression was performed to estimate trends in the age-standardized prevalence of alcohol consumption. Associations of demographic and behavioral factors, perceived health-related effects, social relationships, and the diagnostic history of diseases with alcohol consumption were assessed using multinomial logistic regression.</P><P><B>Results</B></P><P>The prevalence of alcohol consumption remained higher in men during the study period and increased in women. The amount of alcohol consumed has increased in women, especially that from beer and makgeolli, a traditional Korean fermented rice wine. Older participants were less likely to be high-risk drinkers (men and women who drink more than 40 or 20 g/day of alcohol, respectively) and drink Soju, a distilled liquor, and beer, and more likely to drink makgeolli. Educational level was negatively associated with high-risk drinking. However, it was positively associated with the consumption of strong spirits and wine. Smoking was associated with high-risk drinking and the consumption of soju and strong spirits. Engaging in regular exercise and having stress were associated with drinking all types of beverages except for soju.</P><P><B>Conclusions</B></P><P>Sex-specific trends in alcohol consumption were influenced by demographic, behavioral, and perceived health-related factors. The findings will help improve the understanding of alcohol-related problems and provide evidence for establishing country-specific policies and campaigns in Korea.</P>