• Restorative Dentistry and Endodontics
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• 제49권2호
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• pp.21.1-21.8
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• 2024

Objectives: This paper aims to serve as a useful guide for sample size determination for various correlation analyses that are based on effect sizes and confidence interval width. Materials and Methods: Sample size determinations are calculated for Pearson's correlation, Spearman's rank correlation, and Kendall's Tau-b correlation. Examples of sample size statements and their justification are also included. Results: Using the same effect sizes, there are differences between the sample size determination of the 3 statistical tests. Based on an empirical calculation, a minimum sample size of 149 is usually adequate for performing both parametric and non-parametric correlation analysis to determine at least a moderate to an excellent degree of correlation with acceptable confidence interval width. Conclusions: Determining data assumption(s) is one of the challenges to offering a valid technique to estimate the required sample size for correlation analyses. Sample size tables are provided and these will help researchers to estimate a minimum sample size requirement based on correlation analyses.

• Nuclear Engineering and Technology
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• 제52권1호
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• pp.192-205
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• 2020

Seismic design practices and seismic response analyses of civil structures and nuclear power plants (NPPs) have conventionally used the peak ground acceleration (PGA) or spectral acceleration (S_a) as an intensity measure (IM) of an earthquake. However, there are many other earthquake IMs that were proposed by various researchers. The aim of this study is to investigate the correlation between seismic responses of NPP components and 23 earthquake IMs and identify the best IMs for correlating with damage of NPP structures. Particularly, low- and high-frequency ground motion records are separately accounted in correlation analyses. An advanced power reactor NPP in Korea, APR1400, is selected for numerical analyses where containment and auxiliary buildings are modeled using SAP2000. Floor displacements and accelerations are monitored for the non- and base-isolated NPP structures while shear deformations of the base isolator are additionally monitored for the base-isolated NPP. A series of Pearson's correlation coefficients are calculated to recognize the correlation between each of the 23 earthquake IMs and responses of NPP structures. The numerical results demonstrate that there is a significant difference in the correlation between earthquake IMs and seismic responses of non-isolated NPP structures considering low- and high-frequency ground motion groups. Meanwhile, a trivial discrepancy of the correlation is observed in the case of the base-isolated NPP subjected to the two groups of ground motions. Moreover, a selection of PGA or S_a for seismic response analyses of NPP structures in the high-frequency seismic regions may not be the best option. Additionally, a set of fragility curves are thereafter developed for the base-isolated NPP based on the shear deformation of lead rubber bearing (LRB) with respect to the strongly correlated IMs. The results reveal that the probability of damage to the structure is higher for low-frequency earthquakes compared with that of high-frequency ground motions.

• 한국농공학회지
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• 제30권4호
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• pp.45-61
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• 1988

The purpose of this study is to develop regression equations between annual specific sedi- ment of reservoirs and physiographic factors of watersheds. 122 irrigation reservoirs, which have irrigation areas equal to or larger than 200 ha, located in Korea except Cheju province are used in the analysis. Simple regression analyses between the specific annual sediment and each of the physical characteristic factors of the reservoirs are carried out at first. Then, multiple regression analyses between the annual specific sediment and the physical characteristic factors with high correlation coefficients in the simple regression analyses are made. The results obtained from this study are as follows : 1. The results of the sirnple regression analyses show that in each province the watershed area, the length of mainstream, the circumferential length of watershed have high cor- relation coefficients (R=0.814-0.986), and that drainage density, reservoir capacity per watershed area, drainage frequency, basin relief have low correlation coefficients (R=0. 387-0.955). 2. The purposed multiple regression equations between the annual specific sediment of reservoirs and three major characteritic factors of watersheds, namely, the watershed area, the circumferential length of watershed, and the length of mainstream, are proposed as given in Table 2. 3. The result of the simple regression analyses with respect to the reservoir elevation except Jeonnam province, which has very different characteristics comparing to other provinces, shows that watershed area, main stream length and circumferential length have high correlation coefficients (R=0.806-0.884) in low-elevation reservoirs and intermediate- elevation reservoirs, but low correlation coefficients (R=0.639-0.739) in high-elevation reservoirs. 4. With respect to the reservoir elevation, the proposed multiple regression equations bet- ween the annual specific sediment of reservoirs and the three major characteristic factors of watershed which have high correlation coefficients are proposed as given in Table 5.

• Structural Engineering and Mechanics
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• 제87권5호
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• pp.419-429
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• 2023

This study conducts numerical analyses of a thin-walled composite cylinder under axial compression and internal pressure of 10 kPa. Numerical vibration correlation technique and nonlinear postbuckling analyses are conducted using the nonlinear finite element analysis program, ABAQUS. The single perturbation load approach and measured imperfection data are used to represent the geometric initial imperfection of thin-walled composite cylinder. The buckling knockdown factors are derived using present initial imperfection and analysis methods under axial compression without and with the internal pressure. Furthermore, the buckling knockdown factors are compared with the buckling test and computation time are calculated. In this study, derived buckling knockdown factors in present study have difference within 10% as compared with the buckling test. It is shown that nonlinear postbuckling analysis can derive relatively accurate buckling knockdown factor of present thin-walled cylinders, however, numerical vibration correlation technique derives reasonable buckling knockdown factors compared with buckling test. Therefore, this study shows that numerical vibration correlation technique can also be considered as an effective numerical method with 21~91% reduced computation time than nonlinear postbuckling analysis for the derivation of buckling knockdown factors of present composite cylinders.

• 대한음성학회지:말소리
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• 제55권
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• pp.45-60
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• 2005

The purpose of this paper is to represent values of acoustic cues for Korean oral stops in the multi-dimensional space, and to attempt to find possible relationships among acoustic cues through correlation analyses. The acoustic cues used for differentiation of 3 types of Korean stops are closure duration, voice onset time and fundamental frequency of a vowel after a stop. The values of these cues are plotted in the two and three dimensional space to see what the critical cues are for separation of different types of stops. Correlation coefficient analyses show that multi-variate approach to statistical analysis is legitimate, and that there are statistically significant relationships among acoustic cues but Oey are not strong enough to make the conjecture that there is a possible relationship among the articulatory or laryngeal mechanisms employed by the acoustic cues.

• 대한가정학회지
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• 제34권2호
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• pp.315-328
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• 1996

The purpose of this study was to examine how children's sibling relationships were related to their self-esteem. 440 children and their only siblings were asked to respond to two questionnaires concerning the two research variables. The questionnaires used were the SRQ (Furman & Buhrmester, 1985) and the SPPC (Harter, 1985). Ther data were analyzed through correlation analyses, stepwise multiple regression analyses, and canonical correlation analyses. The results were as follows : Warmth·Intimacy and Rivalry (parental partiality toward the child himself/herself) had positive correlations with the child's self-esteem, while sibling Conflict had negative correlations and Relative Status·Power had little correlation. The best predictor of children's self-esteem was sibling Warmth·Intimacy. The next powerful determinants were Conflict and Rivalry. Among the six self-esteem measures, the one predicted best by sibling relationships was Global Self-Worth. The next ones were Behavior·Conduct and Scholastic Competence. The findings revealed that the predictive power of the sibling relationships factors varied considerably according to such status variables as sex and birth order of children and to whether each of the two research variables was analyzed as a whole or at a factor level.

• ETRI Journal
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• 제31권2호
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• pp.151-161
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• 2009

In this paper, we propose an adaptive multiview video coding scheme based on spatiotemporal correlation analyses using hierarchical B picture (AMVC-HBP) for the integrative encoding performances, including high compression efficiency, low complexity, fast random access, and view scalability, by integrating multiple prediction structures. We also propose an in-coding mode-switching algorithm that enables AMVC-HBP to adaptively select a better prediction structure in the encoding process without any additional complexity. Experimental results show that AMVC-HBP outperforms the previous multiview video coding scheme based on H.264/MPEG-4 AVC using the hierarchical B picture (MVC-HBP) on low complexity for 21.5%, on fast random access for about 20%, and on view scalability for 11% to 15% on average. In addition, distinct coding gain can be achieved by AMVC-HBP for dense and fast-moving sequences compared with MVC-HBP.

• 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.

• 한국동물학회지
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• 제24권2호
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• pp.91-98
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• 1981

Deer mice, Peromyscus maniculatus, 의 성체 571마리의 30개 morphometric 형질들을 이용한 cluster analyses에서 두가지의 similarity 행렬식 (Average taxonomic distance와 Correlation coefficient 행렬식)을 이용한 dendrogram이 서로 다르다는 것이 확인되었다. 이들 두가지의 행렬식 중에서 taxarks의 형태적인 유연관계를 나타내는 하나의 dendrogram만을 선택하기 위한 한 객관적방법이 제안되었다. 즉 principal component analysis에 의한 결과를 비교할 표준결과로 이용하는 방법이다.

• 한국게임학회 논문지
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• 제11권4호
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• pp.61-72
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• 2011

콘솔 게임에서 조작도구는 사용자와 콘텐츠를 연결하는 중요한 매개체의 역할을 담당하고 있으며, 조작도구가 기술적으로 발전하고 산업적으로 그 수요가 확대되면서 게임 콘텐츠의 변화를 야기하고 있다. 본 연구는 은유와 환유를 통해 조작방식의 구조주의적 차별점과 궁극적으로 그것이 게임 콘텐츠에 미치는 영향을 살펴보고자 한다. 향후 콘솔 게임 조작도구의 다양화라는 전망 속에서 게임 플랫폼과 콘텐츠의 상관관계 연구는 의의를 가질 수 있을 것으로 본다.