• International Journal of Aerospace System Engineering
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• v.5 no.1
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• pp.9-18
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• 2018

The longitudinal flight parameters of a light airplane are estimated from flight test data by use of the output error method. The reliability of the flight test measurement is examined in engineering judgment, scatter and Cramer-Rao bound, which turns out to be satisfactory with minor defects. Estimated parameter values are validated by comparing the simulated responses with the ones from actual flight tests. The FTD(Flight Training Device) of a light airplane turns out to satisfy the qualification of FAA Level 5 FTD in longitudinal motion. All the necessary practices for generation of high-fidelity data in longitudinal motion of a light aircraft are successfully performed in this study.

• Korean Journal of Child Studies
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• v.25 no.6
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• pp.35-52
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• 2004

The purpose of this study is to explore the relation among mother's rearing attitude in infancy, children's self-concept and the relationship with friends in childhood by using the longitudinal data originated by the Korean Institute for Research in the Behavioral Sciences(KIRBS). Specifically, using Structural Equation Modeling(SEM), the causal relation among the mother's rearing attitude in infancy, children's self-concept and the relationship with friends in childhood were examined across a 8-year-period. The subjects were 68 children(38 boys and 30 girls) from the KIRBS longitudinal data. The results showed that mother's rearing attitude in infancy can be consequential environmental variable factor, and children's self-concept do not play an essential intermediate role between mother's rearing attitude in infancy and the relationship with friends in childhood. This study used a newly attempted method in the field of Human Development.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.5
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• pp.622-626
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• 2002

Growth records over six generations of 686 pigs in SD-II Swine Line were used to estimate the genetic and phenotypic covariance functions for body weight as longitudinal data. A random regression model with Legendre polynomials of age as independent variables was used to estimate the (co)variances among the regression coefficients, thus the coefficients of genetic and permanent environmental covariance functions by restricted maximum likelihood employing the average information algorithm. The results showed that, using litter effect as additional random effect, a reduced order of fit did not describe the data adequately. For all five orders of fit, however, the change trends of genetic and phenotypic (co)variances were very similar from ${\kappa}$=3 onwards.

• International Journal of Contents
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• v.15 no.3
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• pp.7-12
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• 2019

The purpose of this study was to analyze characteristics and patterns of 'better class' by using the longitudinal text mining big data analysis technique from subjective lecture evaluation comments. First, this study classified upper 30% classes to deduce certain characteristics and patterns from every five-year subjective text data for 10 years. A total of 47,177courses (100%) from spring semester 2005 to fall semester 2014 were analyzed from a university at a metropolitan city in the mid area of South Korea. This study extracted meaningful words such as good, course, professor, appreciation, lecture, interesting, useful, know, easy, improvement, progress, teaching material, passion, and concern from the order of frequency 2005-2009. The other set of words were class, appreciation, professor, good, course, interesting, understanding, useful, help, student, effort, thinking, not difficult, explanation, lecture, hard, pleasant, easy, study, examination, like, various, fun, and knowledge 2010-2014. This study suggests that the characteristics and patterns of 'better class' at college, should be analyzed according to different academic code such as liberal arts, fine arts, social science, engineering, math and science, and etc.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1439-1447
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• 2014

Most of literatures on Korean child aggression are based on using the cross-sectional data sets. Although there is a related study with a longitudinal data set, it is assumed that the data sets measured repeatedly in the longitudinal data are mutually independent. A longitudinal data analysis for Korean child aggression is then necessary. This study is to analyze the effect of child development outcomes including academic achievement, self-esteem, depression anxiety, delinquency, victimization by peers, abuse by parents and internet using time on child aggression with Korea Welfare Panel Study data observed three times between 2006 and 2012. Since Korea Welfare Panel Study data have missing values, the missing at random is assumed. The linear mixed effect model and the restricted maximum likelihood estimation are considered.

• The Mathematical Education
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• v.55 no.4
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• pp.447-465
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• 2016

The purpose of this study is to analyze longitudinal trends of students' mathematical affective domain by use of the data mining method. For this purpose, we used the Korea education longitudinal study(KELS 2005) which was the survey data for students' achievement test, affective domain test, teachers' evaluation, and parents' evaluation from $7^{th}$ grader in the year of 2005 to $11^{th}$ grader in the year of 2010. Subjects of this study is a total of 5040 students who answered to the mathematical affective domain survey in KELS 2005. The result findings are as follows. First, students' affective domain had changed negatively as they went up to higher grade. Second, if students' affective domain had built at a certain level in $7^{th}$ grade, the level did not change easily until $11^{th}$ grade. Third, major factors of students' affective domain were shown to be self-efficacy, intrinsic motivation, efforts and patient, and time management.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.654-667
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• 2003

This paper presents a consequence of the systematic approach to identify the aerodynamic parameters of an unmanned aerial vehicle (UAV) equipped with the automatic flight control system. A 3-2-1-1 excitation is applied for the longitudinal mode while a multi-step input is applied for lateral/directional excitation. Optimal time step for excitation is sought to provide the broad input bandwidth. A fully automated programmed flight test method provides high-quality flight data for system identification using the flight control computer with longitudinal and lateral/directional autopilots, which enable the separation of each motion during the flight test. The accuracy of the longitudinal system identification is improved by an additional use of the closed-loop flight test data. A constrained optimization scheme is applied to estimate the aerodynamic coefficients that best describe the time response of the vehicle. An appropriate weighting function is introduced to balance the flight modes. As a result, concurrent system models are obtained for a wide envelope of both longitudinal and lateral/directional flight maneuvers while maintaining the physical meanings of each parameter.

• Journal of muscle and joint health
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• v.8 no.2
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• pp.278-286
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• 2001

With the aging of society a great deal of interest is being placed on the value of longitudinal data in evaluating physiological losses. We present data on test-one/test-two reliability and reproducibility for measures of training, bone density from a longitudinal study of master athletes. Fifty-two males (mean age at test $1=58.2{\pm}9.8\;years$) and thirty-two females ($54.4{\pm}8.8\;years$) were selected from the study population. Bone mineral density was determined using DEXA (Hologic 1500). The characteristics of the subjects are presented below as $means\;{\pm}\;S.D$. The data was imported into the Statistical Package for the Social Science (SPSS 9.0, Chicago, IL). Paired t-tests were performed between visit 1 and visit 2 in subjects. Pearson correlations were performed. The results of this study indicate the measures of training history, body mass and bone density are reasonably stable and reproducible. We conclude that body composition and bone density parameters are stable and reproducible over time in active older subjects. Physiologic measures in master athletes are fairly stable, and reproducible over time Longitudinal studies investigating age-related changes in master athletes need to be conducted on a time schedule of greater than two years.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.201-210
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• 2024

In empirical software engineering research, there is an increased use of questionnaires and surveys to collect information from practitioners. Typically, such data is then analyzed based on overall, descriptive statistics. Overall, they consider the whole survey population as a single group with some sampling techniques to extract varieties. In some cases, the population is also partitioned into sub-groups based on some background information. However, this does not reveal opinion diversity properly as similar opinions can exist in different segments of the population, whereas people within the same group might have different opinions. Even though existing approach can capture the general trends there is a risk that the opinions of different sub-groups are lost. The problem becomes more complex in case of longitudinal studies where minority opinions might fade or resolute over time. Survey based longitudinal data may have some potential patterns which can be extracted through a clustering process. It may reveal new information and attract attention to alternative perspectives. We suggest using a data mining approach to finding the diversity among the different groups in longitudinal studies (agile skeptics). In our study, we show that diversity can be revealed and tracked over time with the use of clustering approach, and the minorities have an opportunity to be heard.

• Journal of the Korean Data and Information Science Society
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• v.25 no.5
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• pp.987-998
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• 2014

The primary purpose of this paper is to derive a benchmark dose lower limit (BMDL) of lead for the attention deficit/hyperactive disorder (ADHD) based on a longitudinal cohort data set which is referred to as CHEER data set. The CHEER data were recently recruited from the Ministry of Environment of S. Korea to investigate the effect of environment on children's health We first confirm the correlation of ADHD with the blood lead level using a linear mixed effect model. We report from the longitudinal characteristic of CHEER data that ADHD scores tend to have "regression to the mean". A dose-response curve of blood lead level with ADHD being the end point is derived and from this dose-response curve a few BMDLs are derived based on corresponding assumptions on the benchmark region.