• 제목/요약/키워드: student-t

검색결과 2,366건 처리시간 0.034초

Coronary Artery Stenosis Quantification for Computed Tomography Angiography Based on Modified Student's t-Mixture Model

  • Sun, Qiaoyu;Yang, Guanyu;Shu, Huazhong;Shi, Daming
    • ETRI Journal
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    • 제39권5호
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    • pp.662-671
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    • 2017
  • Coronary artery disease (CAD) is a major cause of death in the world. As a non-invasive imaging modality, computed tomography angiography (CTA) is now usually used in clinical practice for CAD diagnosis. Precise quantification of coronary stenosis is of great interest for diagnosis and treatment planning. In this paper, a novel cluster method based on a Modified Student's t-Mixture Model is applied to separate the region of vessel lumen from other tissues. Then, the area of the vessel lumen in each slice is computed and the estimated value of it is fitted with a curve. Finally, the location and the level of the most stenoses are captured by comparing the calculated and fitted areas of the vessel. The proposed method has been applied to 17 clinical CTA datasets and the results have been compared with reference standard degrees of stenosis defined by an expert. The results of the experiment indicate that the proposed method can accurately quantify the stenosis of the coronary artery in CTA.

증명에서 경험적 관점의 한계에 대한 중학교 3학년 학생들의 이해 연구 (A study on the understanding of limitations of experiential viewpoints for 9th grade students)

  • 노은환;강정기
    • 한국수학교육학회지시리즈A:수학교육
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    • 제54권1호
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    • pp.13-30
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    • 2015
  • The mathematical object is conceptual. Thus we can not prove the property of mathematical object in experimental viewpoint but in conceptual viewpoint. We performed the experiment for 28 middle school students to investigate whether they understand this. As a result, the majority of student didn't cognize the limit of experimental method. We had also individual interviews with four students. As results, one student was exactly cognizing the limit of experimental method, but he couldn't prove logically. The others didn't cognize the limit of experimental method. They thought that the proposition was already true regardless of the error. And one of them even thought that to be equal approximately was the same of to be equal exactly. Also, one student has confused between the experimental viewpoint and the conceptual viewpoint. This implies that it is necessary to help students understand the limit of experimental method.

GARCH-X(1, 1) model allowing a non-linear function of the variance to follow an AR(1) process

  • Didit B Nugroho;Bernadus AA Wicaksono;Lennox Larwuy
    • Communications for Statistical Applications and Methods
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    • 제30권2호
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    • pp.163-178
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    • 2023
  • GARCH-X(1, 1) model specifies that conditional variance follows an AR(1) process and includes a past exogenous variable. This study proposes a new class from that model by allowing a more general (non-linear) variance function to follow an AR(1) process. The functions applied to the variance equation include exponential, Tukey's ladder, and Yeo-Johnson transformations. In the framework of normal and student-t distributions for return errors, the empirical analysis focuses on two stock indices data in developed countries (FTSE100 and SP500) over the daily period from January 2000 to December 2020. This study uses 10-minute realized volatility as the exogenous component. The parameters of considered models are estimated using the adaptive random walk metropolis method in the Monte Carlo Markov chain algorithm and implemented in the Matlab program. The 95% highest posterior density intervals show that the three transformations are significant for the GARCHX(1, 1) model. In general, based on the Akaike information criterion, the GARCH-X(1, 1) model that has return errors with student-t distribution and variance transformed by Tukey's ladder function provides the best data fit. In forecasting value-at-risk with the 95% confidence level, the Christoffersen's independence test suggest that non-linear models is the most suitable for modeling return data, especially model with the Tukey's ladder transformation.

대학도서관 시설기준에 관한 연구 (A study on standards for college and university library building areas)

  • 손정표
    • 한국도서관정보학회지
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    • 제23권
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    • pp.363-404
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    • 1995
  • This study is to set up a model of minimum and optimum standards for college and university library building areas in Korea. The results of this study are summarized as follows: 1. minimum standards(proposal) At first, Areas needed by factors of space component are as follows: User space --- 0.45 $m^{2}$ per student. Collection space --- 0.0107 $m^{2}$ per volume Staff space --- 10.1 $m^{2}$ per person Space attached to user, collection and staff space --- 5% of the sum of user, collection and staff areas(0.041 $m^{2}$ per student). Nonassignable space --- 25% of the sum of user, collection and staff areas (0.21 $m^{2}$ per student). Next, the formula to calculate the total area of the college and university library building is as follows: N = 0.45T $m^{2}$(a) + 0.0107V $m^{2}$(b) + 10.1S $m^{2}$(c) + 0.05(a+b+c) $m^{2}$, NS = 0.25N $m^{2}$. 2. Optimum standards(proposal) At first, Areas needed by factors of space component are as follows: User spae --- 0.64 $m^{2}$) per student. Collection space --- 0.01 $m^{2}$ per volume Staff space --- 9.7 $m^{2}$ per person Space attached to user, collection and staff space --- 5% of the sum of user, collection and staff areas(0.073 $m^{2}$ per student). Nonassignable space --- 25% of the sum of user, collection and staff areas(0.38 $m^{2}$ per student). Next, the formula to calculate the total area of the college and university library building is as follows: N = 0.64T $m^{2}$(a) + 0.01V $m^{2}$(b) + 9.7S $m^{2}$(c) + 0.05(a+b+c) $m^{2}$, NS = 0.25N $m^{2}$.

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비행교관의 변혁적 리더십이 학생조종사의 심리적 안정감과 학업만족에 미치는 영향 (Effects of Flight Instructor's Transformative Leaderships on Student Pilot's Psychological Stabilities and Learning Satisfactions)

  • 박원태
    • 한국항공운항학회지
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    • 제28권3호
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    • pp.41-51
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    • 2020
  • This research is accomplished to verify objectively how flight instructor's transformative leadership affects student pilot's psychological stabilities and learning satisfactions. Flight instructor's transformative leadership factor divided into individual consideration, intellectual stimulus and charisma from exploring factor analysis. Psychological stability factor subdivided into happiness, concentration and satisfaction. Learning satisfaction factor subdivided into participation, recommendation, persistence, accomplishment and relationship. According to the analysis of flight instructor's transformative leadership effect on psychological stability, it showed that it has statistical significance on happiness, concentration and satisfaction. It also has positive influence on happiness and concentration. The result from regression analysis showed that individual consideration and charisma affected happiness and concentration in order. However, satisfaction from individual consideration, intellectual stimulus and charisma didn't show statistical significance to student pilot's satisfaction. Analysis of flight instructor's transformative leadership on student pilot's learning satisfaction showed statistical significance between them. Intellectual stimulus and charisma had positive influence on student pilot's learning satisfaction. Regression analysis showed charisma and intellectual affect student pilot's learning satisfaction in order.

여고생의 뷰티관심도, 뷰티제품 및 멀티기능 뷰티제품 관심도에 따른 뷰티행동 연구 (A Study on the Beauty Action of the High-School Girl with the Beauty, Beauty Products, and Multi-function Beauty Product Interest)

  • 방기정
    • 패션비즈니스
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    • 제17권4호
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    • pp.124-139
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    • 2013
  • Teenage girls under the influence of the physical changes due to the rapid physical development and appearance are interested. 200 parts were used for the statistical analysis of this research against the common excitation high school student positioned in Seoul. First, there was lots of the girl student managing the appearance due to the psychological satisfaction. And the girl student without the friend of the opposite sex managed the appearance at the psychological satisfaction. Because to be more important, thing including the studying, and etc. was the priority the girl student who doesn't the appearance management did not do the appearance management. Second, the factor found out over one month allowance 50,000 circle to be the very important factor through the beauty action high of the high beauty product concern degree and girl student action of the beauty product concern degree and girl student where there is the friend of the opposite sex. Third, the more the concern degree about the beauty product was high as the concern degree about the beauty was high, the girl student in high school could know that beauty action was high as the concern degree about the multi function beauty product was high.

시뮬레이션기반 실습교육이 간호대학생의 고용가능성, 진로탐색행동 및 진로결정 자기효능감에 미치는 효과 (The Effect of Simulation-based Practice Education on Employability, Career Exploration Behavior and Decision-making Self-efficacy of the Nursing Students)

  • 정미현;서요한
    • 한국응용과학기술학회지
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    • 제36권3호
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    • pp.709-725
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    • 2019
  • 본 연구의 목적은 시뮬레이션기반 실습교육이 간호대학생들의 고용가능성, 진로탐색행동 및 진로결정 자기효능감에 미치는 효과를 확인하고자 시도되었다. 비동등성 대조군 전후설계를 적용한 유사실험설계로 J지역 소재 3학년 학생을 편의표집하여 총 120명의 간호대학생들로, 실험군 60명, 대조군 60명이 연구에 참여하였다. 실험군은 6주간 실험에 참여하였다. 연구결과, 시뮬레이션기반 실습교육은 간호대학생의 고용가능성(t=-2.31, p=.023), 진로탐색행동(t=-3.05, p=.003)을 유의하게 증가시켰으나, 진로결정 자기효능감(t=-.87, p=.387)은 통계적으로 유의한 차이가 없었다. 결론적으로 시뮬레이션기반 실습교육은 간호대학생들의 교육에 유용하므로 강화해야 할 것이다.

Building Science, Technology, and Research Capacity in Developing Countries: Evidence from student mobility and international cooperation between Korea and Guatemala

  • Bonilla, Kleinsy;Salles-Filho, Sergio;Bin, Adriana
    • STI Policy Review
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    • 제9권1호
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    • pp.99-132
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    • 2018
  • Developing countries face numerous challenges in the process of building science, technology, and research capacity; in particular, the formation and accumulation of skilled S&T workforce. The lack of organized and sustainable higher education options (Master and Doctoral programs), nonexistent or low-quality academic programs, and the absence of research-oriented study options are some of the strong contributors for talented students to emigrate to developed countries. At the same time, the consolidation of a global knowledge economy, the internationalization of higher education, and the competition to attract foreign talent in industrialized countries present challenges for underdeveloped nations to retain their already scarce skilled human resources. In this context, student mobility has been used as a policy mechanism to cope with S&T workforce shortages in S&T laggard nations. It has also enabled opportunities for international cooperation to play a key role. While significant literature has been devoted to studying the gains of developed nations with the arrival and potential migration of the mobilized students, few scholarly inquiries have addressed the benefits and losses experienced by their countries of origin. More importantly, limited research can be found on policy options and policy implications for developing countries to deal with the dilemmas presented by the brain-drain/brain-circulation debate. The goal of this article is to study empirical evidence of an international cooperation initiative for student mobility between the Republic of Korea and Guatemala (implemented during 2009-2015). The paper analyzes this particular international cooperation experience from the perspective of the different actors involved and attempts to draw policy implications and policy options for developing countries to deal with potential risks and gains derived from international mobility for their S&T capacity building.

대한치주과학회지에 게재된 학술논문의 통계분석에 대한 평가 (Evaluation of Statistical Analysis of Articles in Journal of Korean Academy of Periodontology)

  • 남민숙;전창길;한경윤;김병옥;신광용
    • Journal of Periodontal and Implant Science
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    • 제30권3호
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    • pp.699-707
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    • 2000
  • The purpose of this study was to analyze the statistical errors of articles in the Journal of Korean Academy of Periodontology from 1973 to 1999. Of the 662 articles examined, 263 were included which analyzed the data. They were classified into 2 groups with time lapse; group 1: 1973∼1989, group 2: 1990∼1999. Authors made checklists for analyzing the data and detecting the errors and analyzed them with professional statistician. The results were as follows: 1. Of 263 atricles which applied statistical method, 40(19.3%) was in group 1, 223(49.0%) in group2. 2. In the number of statistical method applied, 170(64.6%) were analyzed with 1 statistical method, 73(27.8%) with 2 methods, 18(6.8%) with 3 methods, and 2(0.8%) with 4 methods 3. The number of statistical methods applied was 14, and they were applied in order of 119 of ANOVA, 72 of Student t-test, 63 of Paired t-test, 36 of CORRELATION, and 21 of Mann- Whitney U test. 4. In 87(33.1%) of 263 articles and in 18 error items, statistical errors were found out. In group I, 9 items (55%) of error were found out, and were in order of 5 of Student t-test instead of Paired t-test, and 4 of unnecessary statistical analysis. In group II, 16 items (29.1%) of error were found out, and were in order of 22 of Student t-test instead of Paired t-test, 7 of no multiple comparison test after ANOVA, 6 of Student t-test instead of ANOVA, 6 of unnecessary statistical analysis, and 5 of ANOVA instead of Paired t-test. In conclusion, the results noted that statistical analyses were increased, but statistical errors were decreased with time. But authors suggest that researchers should refer to standard statistical texts and seek advice from professional statisticians to avoid the statistical errors.

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현실주의 수학교육론에 근거한 비율그래프 지도에 관한 연구 (A Study on Teaching of Ratio Graph based on Realistic Mathematics Education)

  • 윤재훈;류성림
    • 한국수학교육학회지시리즈C:초등수학교육
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    • 제11권1호
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    • pp.39-57
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    • 2008
  • 본 연구에서는 현실주의 수학교육 이론을 바탕으로 '비율그래프' 단원을 재구성한 수업이 학생들의 수학 학업성취도와 수학적 성향에 어떤 영향을 주는지를 알아봄으로써 교실 수업을 개선하기 위한 것이다. 연구 대상은 6학년 학생 68명(실험반 34명, 비교반 34명)이었으며, 수업은 MiC 교재를 참고하여 재구성한 프로그램을 8차시에 걸쳐 실시하였다. 본 연구를 통해 얻은 결론은 다음과 같다. 첫째, 현실주의 수학교육론에 근거하여 재구성한 교재를 활용한 수업이 학습자의 수학 학업성취도 향상에 긍정적인 영향을 미치는 것으로 확인되었다. 둘째, 현실주의 수학교육론에 근거하여 재구성한 교재를 활용한 수업이 학습자의 수학적 성향에 긍정적인 영향을 미치는 것으로 확인되었다.

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