Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle

Yoo, Yeon Hwa,Kim, Hak-Sun,Lee, Young Han,Yoon, Choon-Sik,Paek, Mun Young,Yoo, Hanna,Kannengiesser, Stephan,Chung, Tae-Sub,Song, Ho-Taek,Suh, Jin-Suck,Kim, Sungjun The Korean Society of Radiology 2015 KOREAN JOURNAL OF RADIOLOGY Vol.16 No.5

<P><B>Objective</B></P><P>To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard.</P><P><B>Materials and Methods</B></P><P>Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences.</P><P><B>Results</B></P><P>A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (<I>p</I> < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (<I>p</I> < 0.001), as compared with two- or three-echo methods.</P><P><B>Conclusion</B></P><P>T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.</P>

Application of imputation methods with adjusting multi-center effect on Crohns disease data in Korea

Hanna Yoo 한국데이터정보과학회 2018 한국데이터정보과학회지 Vol.29 No.2

The purpose of this study is to assess the risk factors for recurrence time after the first abdominal surgery in Korean patients with Crohns disease (CD). CD patients who underwent abdominal surgery from January 2000 to December 2009 were collected from seventeen university hospitals (Lee et al. 2012). We assessed the risk factors for recurrence time after the first abdominal surgery CD using Cox regression analysis with imputing the missing covariates using single and multiple imputation methods and also adjusting for the multi-center effect. We compared our results with the complete case analysis. Using imputation methods with considering the multi-center effect, model performance was improved. Comparing between the imputation methods, multiple imputation method showed better performance than single imputation method.

Comparison of missing data methods in clustered survival data using Bayesian adaptive B-Spline estimation

Yoo, Hanna,Lee, Jae Won The Korean Statistical Society 2018 Communications for statistical applications and me Vol.25 No.2

In many epidemiological studies, missing values in the outcome arise due to censoring. Such censoring is what makes survival analysis special and differentiated from other analytical methods. There are many methods that deal with censored data in survival analysis. However, few studies have dealt with missing covariates in survival data. Furthermore, studies dealing with missing covariates are rare when data are clustered. In this paper, we conducted a simulation study to compare results of several missing data methods when data had clustered multi-structured type with missing covariates. In this study, we modeled unknown baseline hazard and frailty with Bayesian B-Spline to obtain more smooth and accurate estimates. We also used prior information to achieve more accurate results. We assumed the missing mechanism as MAR. We compared the performance of five different missing data techniques and compared these results through simulation studies. We also presented results from a Multi-Center study of Korean IBD patients with Crohn's disease(Lee et al., Journal of the Korean Society of Coloproctology, 28, 188-194, 2012).

Sample size calculations for clustered count data based on zero-inflated discrete Weibull regression models

Hanna Yoo 한국통계학회 2024 Communications for statistical applications and me Vol.31 No.1

In this study, we consider the sample size determination problem for clustered count data with many zeros. In general, zero-inflated Poisson and binomial models are commonly used for zero-inflated data; however, in real data the assumptions that should be satisfied when using each model might be violated. We calculate the required sample size based on a discrete Weibull regression model that can handle both underdispersed and overdispersed data types. We use the Monte Carlo simulation to compute the required sample size. With our proposed method, a unified model with a low failure risk can be used to cope with the dispersed data type and handle data with many zeros, which appear in groups or clusters sharing a common variation source. A simulation study shows that our proposed method provides accurate results, revealing that the sample size is aected by the distribution skewness, covariance structure of covariates, and amount of zeros. We apply our method to the pancreas disorder length of the stay data collected from Western Australia.

Application of discrete Weibull regression model with multiple imputation

Yoo, Hanna The Korean Statistical Society 2019 Communications for statistical applications and me Vol.26 No.3

In this article we extend the discrete Weibull regression model in the presence of missing data. Discrete Weibull regression models can be adapted to various type of dispersion data however, it is not widely used. Recently Yoo (Journal of the Korean Data and Information Science Society, 30, 11-22, 2019) adapted the discrete Weibull regression model using single imputation. We extend their studies by using multiple imputation also with several various settings and compare the results. The purpose of this study is to address the merit of using multiple imputation in the presence of missing data in discrete count data. We analyzed the seventh Korean National Health and Nutrition Examination Survey (KNHANES VII), from 2016 to assess the factors influencing the variable, 1 month hospital stay, and we compared the results using discrete Weibull regression model with those of Poisson, negative Binomial and zero-inflated Poisson regression models, which are widely used in count data analyses. The results showed that the discrete Weibull regression model using multiple imputation provided the best fit. We also performed simulation studies to show the accuracy of the discrete Weibull regression using multiple imputation given both under- and over-dispersed distribution, as well as varying missing rates and sample size. Sensitivity analysis showed the influence of mis-specification and the robustness of the discrete Weibull model. Using imputation with discrete Weibull regression to analyze discrete data will increase explanatory power and is widely applicable to various types of dispersion data with a unified model.

Alteration of microRNA 340-5p and Arginase-1 Expression in Peripheral Blood Cells during Acute Ischemic Stroke

Yoo, Hanna,Kim, Jinkwon,Lee, Ae-Ri,Lee, Ji-Min,Kim, Ok-Joon,Kim, Jin-Kyeoung,Oh, Seung-Hun Springer-Verlag 2019 Molecular Neurobiology Vol.56 No.5

맞춤형 챗봇 서비스 개발을 위한 성격(Personality) 중심의 인터랙션 디자인 가이드라인 연구

유한나(Hanna Yoo),이지현(Jihyun Lee) 한국디자인학회 2018 한국디자인학회 학술발표대회 논문집 Vol.2018 No.11

AI스피커 기반의 스마트홈에서 서비스 디자인을 위한 태스크 플로우 가시화 툴킷 제안

유한나(Yoo, Hanna),이지현(Lee, Jihyun) 인제대학교 디자인연구소 2018 Journal of Integrated Design Research (JIDR) Vol.17 No.3

연구배경: 최근 4차 산업혁명으로 인해 핵심 기능인 인공지능 기술이 발전하기 시작하였으며, 특히 사물인터넷은 인공지능 스피커와 결합되어 스마트홈 환경에서 새로운 사용자 경험을 제공하고 있다. 이러한 스마트홈 환경에서는 다수의 사물인터넷 기기와 인공지능 허브의 기능이 서로 결합되어 사용됨에 따라 복합적인 프로세스가 발생되며, 사용자는 다양한 방식의 인터랙션을 통해 사물을 제어할 수 있다. 연구방법: 본 연구에서는 AI스피커 기반의 스마트홈에서 전체적인 흐름과 각각의 디바이스 사용 흐름을 조망할 수 있는 태스크 플로우 가시화 툴킷을 제안하고자 한다. 그리고 개발한 툴킷의 사례 적용 및 전문가 평가를 통해 툴킷의 가치를 검증하였다. 연구결과: 스마트홈을 위한 태스크 플로우 가시화 툴킷은 AI스피커와 홈 사물인터넷 기기 간의 다양한 인터랙션 방식과 연결성뿐만 아니라 사용자와 지원업체와의 관계를 고려하여 프로세스를 가시화할 수 있다. 또한 다양한 사물인터넷 및 인공지능 서비스의 태스크 플로우가 키트형태로 제공되어, 디자이너는 쉽게 스마트홈의 프로세스를 제작할 수 있다. 결론: 본 연구에서 개발된 툴킷은 스마트홈에서 인공지능 스피커와 사물인터넷이 결합되어 발생되는 복합적인 프로세스를 가시화하여, 전반적인 프로세스를 조망하는 동시에 세부적인 플로우를 비교하여 서비스 간의 접점을 파악하는데 의미가 있다. 더 나아가 툴킷을 통해 그려진 플로우를 키트로 재활용함으로써, 다수의 서비스가 결합된 태스크 플로우를 쉽게 제작하고 타서비스의 접점과 기회영역을 발굴할 수 있을 것이다. Background: Recently, artificial intelligence technology, which is a core technology, has been developed due to the 4th industrial revolution. Especially, the Internet of Things has combined with artificial intelligent speakers to provide a new user experience in a smart home environment. In smart home environment, a complex process is created as combined use of many IoTs and AI hubs. And users can control devices through various types of interaction. Methods: In this study, a task flow toolkit was purposed to look at the entire flow and each devices usage flow in the smart home based on AI speaker. Also toolkit is validated the value by applying case to toolkit and expert evaluating. Result: The task flow toolkit for a smart home can visualize process taking into account the relationship user and support provider as well as various interaction types and connectivity between AI speakers and home IoTs. In addition, the task flows of various IoTs and artificial intelligence services are provided in kit form, so designers can easily create process of smart home. Conclusion: The toolkit developed in this study is meaningful to look at the overall process, at the same time to compare the details of the flows. So it can help to find the contact point between the services by visualizing complex process occurred from combination of AI speakers and IoTs in smart home. Furthermore, by reusing the flow made from toolkit, designer can easily create a combined workflow of multiple services and discover opportunity with third party services.

특수학급 미설치 소규모 중학교의 통합교육 실천에 대한 일반교사의 경험과 인식

유한나(Yoo, Hanna),이미숙(Lee, Misuk) 한국통합교육학회 2021 통합교육연구 Vol.16 No.1

본 연구는 특수교육대상자는 재학 중이나 특수학급이 설치되어 있지 않은 소규모 학교의 사례를 통해 통합교육이 어떠한 모습으로 이루어지고 있으며, 일반교사는 특수교육대상학생에 대해 어떠한 인식을 가지고 있는지를 살펴보고자 하였다. 본 연구를 위해 소규모 학교인 빛나중학교의 사례를 살펴보았으며, 이 학교에 재직 중인 일반교사 4명을 대상으로 심층 면담을 실시하였다. 본 연구의 결과는 다음과 같다. 첫째, 빛나중학교 교사는 특수교육대상학생의 적응과 성장을 돕기 위해 지속적인 일상생활 지도, 특수교육대상학생과의 유대관계 형성 등의 노력을 기울이고 있었다. 둘째, 빛나중학교 교사는 특수교육대상학생을 위해 맞춤형 학습지도의 제공을 통해 특수교육대상학생과 함께하는 수업을 만들기 위해 노력하고 있었다. 셋째, 빛나중학교 교사는 통합교육 환경에서의 수업관련 어려움을 언급하였고, 특수교육대상학생에 대한 지도가 적절하게 이루어지고 있는지에 대한 고민을 나타내었다. 마지막으로, 빛나중학교 교사는 특수학급이 미설치된 소규모 학교에서 통합교육을 성공적으로 실행하기 위해서는 학교 차원에서의 지원과 교육청 차원에서의 지원이 마련될 필요가 있다고 하였다. The purpose of this study is to understand the meaning of inclusive education in a small middle school without a special class and to help the successful development of inclusive education by presenting the direction of inclusive education in the future. To this end, the results were obtained by having in-depth interviews with four general teachers who were employed in a small-scale middle school not installed in a special class. Research results were as follows. In the first, small middle school without a special class, teachers were showing interest in students subject to special education. Second, in a small middle school without a special class, teachers were implementing a wild attempt to guarantee students of special education universities the right to study. Third, there were restrictions on inclusive education due to the interest and efforts of special education university students. Finally, for successful inclusive education, general teachers could see that they needed support at the education office and school level.

사회적경제 조직의 조직 양면성과 경제적·사회적 성과

유한나(Hanna Yoo),한상일(Sang-Il Han) 피터드러커 소사이어티 2021 창조와 혁신 Vol.14 No.4

사회적경제 조직의 성공과 실패는 경제적 성과와 사회적 성과의 달성을 위해 운영상의 효율성을 추구하고 새로운 기회를 탐색하는 탐색적·적응적 활동의 조화에 달려있다. 사회적경제 조직 분야의 연구는 성과에의 다양한 영향 요인을 제시하고 있는 반면 구체적인 운영 전략에 관한 연구가 부족하고, 특히 지속가능한 성과 달성의 주요 요소로 연구되고 있는 조직 양면성과 성과를 연결하여 분석하려는 시도는 없었다. 본 연구의 목적은 사회적경제 조직의 조직 양면성(탐색, 활용)이 성과 (경제적, 사회적)에 미치는 영향을 실증 규명하는 것이다. 전국 605개 사회적경제 조직의 자료를 수집하여 분석한 결과, 첫째, 조직 양면성의 두 요인인 탐색과 활용을 기준으로 구분한 4개 집단 중 양면성이 높은 조직이 양면성이 낮은 조직에 비해 성과가 높았으며, 그중 활용 중심 조직이 탐색 중심 조직과 낮은 양면성 조직에 비해 성과가 높았다. 둘째, 단일 조직 양면성 지수를 산출해 성과에 미치는 영향을 분석한 결과, 조직 양면성이 경제적 성과와 사회적 성과에 긍정적 영향을 미치며, 조직 규모가 클수록 상법상 회사일수록 성과가 향상됨을 확인하였다. 본 연구는 사회적경제 조직을 대상으로 조직 양면성의 성과에의 영향을 최초로 검증한 것으로, 조직 양면성이 사회적경제 조직의 자원 제약 조건에도 불구하고 지속적 성과 창출을 위한 운영 전략이 될 수 있다는 점에서 의의가 있다. The success and failure of social economy organizations(SEOs) depend on the balanced achievement of both economic and social performance, the pursuit of efficiency through rational management of the organization, and the harmony of exploratory and adaptive activities exploring new demands and opportunities. However, while studies analyzing social and economic performance in the area of SEOs present various results, no studies have been found analyzing the two sides of organizational ambidexterity on their performance. Therefore, this study empirically analyses the effect of organizational ambidexterity (exploration, exploitation) of SEOs on performance (economic, social). To this end, the 605 SEOs data was collected and analyzed. As a result of the difference analysis between groups, the performance of SEOs with high ambidexterity was higher than that of organizations with low ambidexterity. In addition, as a result of the regression analysis using a multiplication method, it was confirmed that ambidexterity had a positive effect on both economic and social performance. The significance of this study is that it is the first research that verified the impact of organizational ambidexterity on the performance of SEOs, and it gives operational implications to SEOs that lack slack resources.