• Journal of the Korean Statistical Society
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• 제30권4호
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• pp.541-550
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• 2001

This paper considers a panel data regression model in which the disturbances follow a nested error components with serial correlation. Given this model, this paper derives several Lagrange Multiplier(LM) testis for the presence of serial correlation as well as random individual effects, nested effects, and for existence of serial correlation given random individual and nested effects.

• Progress in Superconductivity
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• 제12권1호
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• pp.46-50
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• 2010

In the superconducting $Sr_2VO_3FeAs$, containing bimetallic layers, with maximum $T_c{\approx}\;46\;K$ correlation effects on V ions have been investigated using LDA+U method. Within the local density approximation (LDA) this system has the one-third filled $t_{2g}$ manifold of V, decomposed into $d_{xy}$ of bandwidth W=2 eV and nearly degenerate $d_{zx}d_{yz}$ of W=1 eV. Consideration of correlation effects leads to a metal-insulator transition on V ions $t^{2\uparrow}_{2g}\;{\rightarrow}\;d^{1\uparrow}_{xz}\;d^{1\uparrow}_{yz}$ at the critical on-site Coulomb repulsion $U_c$= 3.5 eV. At U=4 eV, the electronic structure, in which V ions are insulating, leads to several van Hove singularities near $E_F$ and similar Fermiology with other pnictides. Applying U to V ions results in increasing Fe moment as well as V moment, indicating somewhat hybridization between Fe and V ions even though this system is strongly 2-dimesional. Our results show possible importance of correlation effects on this system.

• 생명과학회지
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• 제10권2호
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• pp.177-181
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• 2000

This study was conducted to estimate the genetic parameters such as combining ability, heritabilities and correlation coefficients forsome agronomic characters by 6$\times$6 dialled crosses of barley. The results obtained were summarized as follows. Mean squares of general combining ability(GCA) and specific combining ability(SCA) were significant for all characters observed. Mean squares of general combining ability for all characters were expressed as higher values than those of specific combining ability. Jecheon #5 showed the high general combining ability effects for culm length, and Waegwanpimack #1 showed the highest general combining ability effects for tiller number. Cygne also showed the high general combining ability effects for spike length and 1,000 grains weight. Furthermore, Plumage was expressed with the highest general combining ability effects for spike length and 1,000 grains weight. Furthermore, Plumage was expressed with the highest general combining ability effects for number of grains per spike. In specific combining ability effects, Samdugjeonbug # 45$\times$Plumage showed the high value for culm length, and Suwon #6 $\times$Waegwanpimack #1$\times$ was expressed with the highest specific combining ability effects for tiller number. Jecheon #5$\times$Plumage also showed the high specific combining ability effects for spike length and number of grains per spike. Suwon #6$\times$Cygne showed the high specific combining ability effects for 1,000 grains weight. The heritabilities of spike length an number of grains per spike were over 90%. In correlation coefficients among characters, relationships between culm length and tiller number, culm length and spike length, culm length and 1,000 grains weight, and spike length and 1,000 grains weight showed highly positively correlation.

• 한국지역사회생활과학회지
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• 제27권1호
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• pp.5-17
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• 2016

The purpose of this study was to examine the mediating effects of young children's shyness on the relationship between teacher-children relationship and young children's social competence. The subjects of the study were 270 children from three years to five years old and their teachers in Busan. Frequency, t-test, Cronbach ${\alpha}$, Pearson's correlation coefficients, and hierarchial regression were used for data analysis. The results were as follows: first, teacher-children intimacy showed positive correlation with the young children's social competence. Teacher-children conflict showed negative correlation with the young children's social competence. Second, teacher-children intimacy showed negative correlation with the young children's shyness. Teacher-children conflict showed positive correlation with the young children's shyness. Third, young children's shyness showed negative correlation with the young children's social competence. Fourth, young children's shyness had partial mediating effects on the relationship between teacher-children intimacy and young children's sociability. Young children's shyness had partial mediating effects on the relationship between teacher-children intimacy and young children's popularity and leadership. Young children's shyness had partial mediating effects on the relationship between teacher- children conflict and young children's sociability. Young children's shyness had partial mediating effects on the relationship between teacher-children conflict and young children's popularity and leadership.

• Wind and Structures
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• 제8권3호
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• pp.163-178
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• 2005

Wind-induced mean and dynamic interference effects of tall buildings are studied in detail by a series of wind tunnel tests in this paper. Interference excitations of several types of upwind structures of different sizes in different upwind terrains are considered. Comprehensive interference characteristics are investigated by artificial neural networks and correlation analysis. Mechanism of the wakes vortex-induced resonance is discussed, too. Measured results show significant correlations exist in the distributions of the interference factors of different configurations and upwind terrains and, therefore, a series of relevant regression equations are proposed to simplify the complexity of the multi-parameter wind induced interference effects between two tall buildings.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.82-87
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• 2020

The comprehensive and physics-based compact noise models for advanced CMOS devices were presented. The models incorporate important physical effects in nanoscale MOSFETs, such as the low frequency correlation effect between the drain and the gate, the trap-related phenomena, and QM (quantum mechanical) effects in the inversion layer. The drain current noise model was improved by including the tunneling assisted-thermally activated process, the realistic trap distribution, the parasitic resistance, and mobility degradation. The expression of correlation coefficient was analytically described, enabling the overall noise performance to be evaluated. With the consideration of QM effects, the comprehensive low frequency noise performance was simulated over the entire bias range.

• 자원ㆍ환경경제연구
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• 제28권3호
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• pp.327-354
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• 2019

본 논문에서는 한국의 미세먼지 발생원인을 분석하는 과정에서 기존 논문에서는 고려하지 않았던 지역 간 공간상관성(Spatial correlation)을 고려한 패널계량분석을 진행하였다. 기존 환경쿠즈네츠곡선(EKC, Environmental Kuznets Curve)에 대한 연구들에서, 인접한 국가 및 지역 간에 오염물질의 상호영향이 존재할 가능성이 있음에도 각 유닛이 독립이라고 가정한다. 본 논문에서는 한국의 미세먼지농도에 대한 지역 패널데이터를 이용하여 기존 EKC가 지역의 상호상관성을 고려하는 때도 성립할 수 있으며, 이러한 영향을 고려하지 않았을 때 미세먼지농도의 원인에 대해 과소 혹은 과대 추정될 수 있음을 규명하였다.

• 대한물리치료과학회지
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• 제18권2호
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• pp.17-28
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• 2011

Purpose: The aim of this study was to ascertain the effects of the lower extremity muscle strengthening exercise on balance and ambulation of children with cerebral palsy. Methods: 10 subjects who participated in this research undertook the 12-week the lower extremity muscle strengthening exercise program, which consisted of a series of mat exercises and sling exercises. The statistical significances were examined by using Wilcoxon signed-rank test, a non-parametric test, for evaluating the improvement of balance and ambulation of the subjects. In order to evaluate the correlation among the variables, Pearson's correlation coefficients were also calculated. In all statistical analyses the significance level was selected as ${\alpha}$=0.05. Results: Berg balance scale(BBS) was significantly increased after the intervention(p<.05). Percentage weight bearing(PWB) was decreased after the intervention, but there was no significant difference. Time up and go test(TUG) value was significantly decreased(p<.05). Gait velocities was increased after the intervention, but there was no significance. Stride length, step lengths of the affected side and the sound side were significantly increased after the intervention(p<.05). In the correlation analyses of the measures before the intervention, TUG had significant negative correlation to BBS and gait velocity(p<.05). Stride length, step lengths of the sound side and the affected side had significant positive correlation between themselves(p<.01). In the correlation analyses of the measures after the intervention, TUG had significant negative correlation to BBS and gait velocity(p<.05). BBS revealed significant positive correlations to stride length, step lengths of the sound side and the affected side(p<.05). Stride length, step lengths of the sound side and the affected side had significant positive correlation between themselves(p<.01). Conclusion: Based upon the outcomes as above, it is likely that the muscle strength exercises have substantial effects on balance and ambulation of children with cerebral palsy. Thus various lower extremity muscle strengthening exercise programs are required to be studied and developed in order to contribute to functional improvements of children with cerebral palsy.

• 한국전자파학회논문지
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• 제19권2호
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• pp.152-160
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• 2008

본 논문에서는 위상 잡음의 거리 상관 효과에 따른 직접 변환 방식의 UHF 대역 RFID 리더의 성능을 분석한다. UHF RFID 시스템은 일반적 인 무선 통신 방식과는 다르게 송신 캐 리어를 발생하는 LO 신호가 동시에 수신기의 국부 발진기로 사용되며, 이에 따라 태그 신호와 LO 신호 간의 거리 상관 효과에 의한 주기적인 신호 간섭 및 위상 잡음 감소 효과가 발생한다. 주기적인 신호 간섭 효과는 이론 및 시뮬레이션을 통해 I와 Q신호를 I/Q 다이버시티 개념으로 전력 결합함으로써 제거할 수 있음을 확인하였다. 위상 잡음 감소 효과는 전형적인 UHF 대역에서 동작하는 LO의 위상 잡음에 대한 전력 밀도 스펙트럼이 태그-리더 거리 및 옵셋 주파수에 따라 변화됨을 확인하였고, 이를 이용하여 심볼 에러 성능을 시뮬레이션 하였다. 시뮬레이션 결과, 심볼 에러에서 위상 잡음의 영향은 태그 변조 방식 중 PSK에서 특히, 변조 각도가 작을 때 크게 나타나지만, 거리 상관 효과에 의해 실제 위상 잡음이 감소되어 그 영향이 미비해짐을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제11권4호
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• pp.441-444
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• 1998

The negative direct-maternal genetic correlation $(r_{dm})$ for weaning weight is inflated when data are analyzed with model ignoring sire-by-year interactions (SY). An analytical study investigating the consequences of ignoring SY was undertaken. The inflation of negative correlation could be due to a functional relationship of design matrices for additive direct and maternal genetic effects to that for sire effects within which SY effects were nested. It was proven that the maternal genetic variance was inflated by the amount of reduction for sire variance; the direct genetic variance was inflated by four times the change for maternal genetic variance; and the direct-maternal genetic covariance was deflated by twice the change for maternal genetic variance. The findings were agreed to the results in previous studies.