• 천문학회보
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• 제35권2호
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• pp.51.2-51.2
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• 2010

We have investigated 63 intense geomagnetic storms (Dst $\leq$ -100 nT) that occurred from 1998 to 2006. Using these events, we compared Dst forecast models: Burton et al. (1975), Fenrich and Luhmann (1998), O'Brien and McPherron (2000a), Wang et al. (2003), and Temerin and Li (2002, 2006) models. For comparison, we examined a linear correlation coefficient, RMS error, the difference of Dst minimum value (${\Delta}$peak), and the difference of Dst minimum time (${\Delta}$peak_time) between the observed and the predicted during geomagnetic storm period. As a result, we found that Temerin and Li model is mostly much better than other models. The model produces a linear correlation coefficient of 0.94, a RMS (Root Mean Square) error of 14.89 nT, a MAD (Mean Absolute Deviation) of ${\Delta}$peak of 12.54 nT, and a MAD of ${\Delta}$peak_time of 1.44 hour. Also, we classified storm events as five groups according to their interplanetary origin structures: 17 sMC events (IP shock and MC), 18 SH events (sheath field), 10 SH+MC events (Sheath field and MC), 8 CIR events, and 10 nonMC events (non-MC type ICME). We found that Temerin and Li model is also best for all structures. The RMS error and MAD of ${\Delta}$peak of their model depend on their associated interplanetary structures like; 19.1 nT and 16.7 nT for sMC, 12.5 nT and 7.8 nT for SH, 17.6 nT and 15.8 nT for SH+MC, 11.8 nT and 8.6 nT for CIR, and 11.9 nT and 10.5 nT for nonMC. One interesting thing is that MC-associated storms produce larger errors than the other-associated ones. Especially, the values of RMS error and MAD of ${\Delta}$peak of SH structure of Temerin and Li model are very lower than those of other models.

• 디지털융복합연구
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• 제18권10호
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• pp.361-370
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• 2020

본 연구는 간호대학생의 월경태도, 일상생활 스트레스, 임상실습 스트레스가 월경전증후군에 미치는 영향을 확인하기 위한 서술적 조사연구이다. 수집된 자료는 SPSS 22.0 프로그램을 이용하여 t-test, one-way ANOVA, Pearson's correlation coefficient, multiple linear regression으로 분석하였다. 분석결과 월경전증후군은 대상자의 월경에 대한 태도(r=.28, p=.004), 일상생활 스트레스(r=.31, p=.001) 그리고 임상실습 스트레스(r=.29, p=.003)와 정적 상관관계가 있는 것으로 나타났다. 회귀분석을 한 결과 월경전증후군에 영향을 미치는 예측 요인은 운동의 규칙성과 월경통으로 나타났는데 즉, 운동을 규칙적으로 하지 않을수록(β=-.18, p=.006), 월경통이 심할수록(β=.51, p=.000) PMS를 더 경험한 것으로 나타났다. 회귀모형의 설명력은 38.0%이었다.

• Korean Journal of Radiology
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• 제19권6호
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• pp.1021-1030
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• 2018

Objective: We evaluated the effect of various patient characteristics and time-density curve (TDC)-factors on the test bolus-affected vessel enhancement on coronary computed tomography angiography (CCTA). We also assessed the value of generalized linear regression models (GLMs) for predicting enhancement on CCTA. Materials and Methods: We performed univariate and multivariate regression analysis to evaluate the effect of patient characteristics and to compare contrast enhancement per gram of iodine on test bolus (${\Delta}HUTEST$) and CCTA (${\Delta}HUCCTA$). We developed GLMs to predict ${\Delta}HUCCTA$. GLMs including independent variables were validated with 6-fold cross-validation using the correlation coefficient and Bland-Altman analysis. Results: In multivariate analysis, only total body weight (TBW) and ${\Delta}HUTEST$ maintained their independent predictive value (p < 0.001). In validation analysis, the highest correlation coefficient between ${\Delta}HUCCTA$ and the prediction values was seen in the GLM (r = 0.75), followed by TDC (r = 0.69) and TBW (r = 0.62). The lowest Bland-Altman limit of agreement was observed with GLM-3 (mean difference, $-0.0{\pm}5.1$ Hounsfield units/grams of iodine [HU/gI]; 95% confidence interval [CI], -10.1, 10.1), followed by ${\Delta}HUCCTA$ ($-0.0{\pm}5.9HU/gI$; 95% CI, -11.9, 11.9) and TBW ($1.1{\pm}6.2HU/gI$; 95% CI, -11.2, 13.4). Conclusion: We demonstrated that the patient's TBW and ${\Delta}HUTEST$ significantly affected contrast enhancement on CCTA images and that the combined use of clinical information and test bolus results is useful for predicting aortic enhancement.

• 미래기술융합논문지
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• 제2권3호
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• pp.25-32
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• 2023

본 연구는 응급구조(학)과 대학생을 대상으로 코로나19에 대한 지식 및 태도와 감염관리 수행도 간의 관련성을 알아보기 위해 시행하였다. 연구 대상은 전라남북도, 광주광역시에 소재한 3-4년제 응급구조(학)과에 재학 중인 대학생 154명이고, 수집된 자료는 SPSS/WIN 16.0을 이용하여 빈도와 백분율, 합(Sum), 평균 및 표준편차, t-test, ANOVA(Scheffe), Pearson's Correlation Coefficient, Multiple Linear Regression으로 분석하였다. 응급구조(학)과 대학생들의 감염관리 수행도에 코로나19에 대한 태도와 지식 순으로 영향을 미쳤다. 따라서 응급구조(학)과 대학생들의 감염관리 수행도를 높이기 위해 코로나19에 대한 지식 및 태도를 향상시킬 수 있는 정규 또는 비정규 교육과정, 다학제적 교육과정 개발 및 적용이 필요하다.

• 대한기계학회논문집A
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• 제29권2호
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• pp.232-238
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• 2005

In this study the four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Ultrasonic tests were performed to get the correlation with fracture toughness. The modified theoretical Vary's equation, considering nonlinear response due to material degradation, was proposed for the correlations between ultrasonic parameters and fracture toughness. Experimental results indicate that ultrasonic attenuation coefficient, velocity and nonlinear parameters produce the correlations with fracture toughness and yield strength.

• Tribology and Lubricants
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• 제7권2호
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• pp.46-50
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• 1991

The Frictional behavior in single crystal (111) p-type silicon as influenced by electolytic solutions have been studied. Linear scratching by diamond indentor was carried out to show the variation of friction between silicon and diamond indentor immersed in electrolytic solutions. The results indicate that concentration of the solutions influence the fricational coefficient. In addition there is a correlation between measured zeta-potential and frictional coefficients. The zeta-potential in various concentrations was measured to estimate the variation of the Peierls energy. The proposed model predicts a minimum frictional coefficient near a concentration of $10^{-3}$ M/l NaOH in deionized water and explains the chemomechanical effect observed in this study.

• 물과 미래
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• 제16권3호
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• pp.159-169
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• 1983

본 연구는 하천의 DO 기준을 유지하기 위해 하천유역내의 각 처리장에 요구되는 폐수처리의 최적효율과 최소처리비용의 조합을 결정하는 선형계획법에 있어서 제약조건의 제식(inventory equations)으로 이용되는 Camp-Dobbinstlr과 Streeter-Phelps 식에 의한 최적수질관리의 해를 상호 비교분석하였다. 그 결과 상관관계가 0.997로 강상관관계를 보여 주었고 측정하기 어려운 R, A, K$$의 파라메터를 영으로 가정한 Streeter-Phelpstlr을 선형계획법의 제약조건의 제식으로 사용하여 최적해를 구하여도 만족함을 줄 수 있음을 알았으며 이 결과로 실제 하천유역을 대상으로 하여 하천유역의 최적수질 관리의 해를 구하였다.

• 대한화학회지
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• 제7권4호
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• pp.264-270
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• 1963

前報에서 誘導한 置換基效果 一般關係式은 溶媒組成에 따르는 常數, Y를 potential energy 項에 代置함으로서 solvolysis 反應에 適用할 수가 있다. 新方程式, $\Delta{\Delta}H^\neq=a'Y+b\Delta{\Delta}S^\neq$, 의 適用性은 文獻에 報告된 35個反應에 對한 直線關係를 調査해 봄으로서 檢討하였다. 結果로 平均 相關係數 0.977을 얻었고, 따라서 이 方程式이 solvolysis反應에 一般的으로 適用됨을 밝혔고, 또 Grunwald-Winstein의 式이 지니는 몇몇 難點을 解決할 수가 있음을 알 수 있었다. enthalypy-entopy 直線效果는 外部 enthalpy와 外部 entropy에 限한 것이며, 嚴格히 말해서 外部 enthalpy entropy 直線效果임을 强調하였다.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3865-3872
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• 2011

A quantitative structure-property relationship (QSPR) study was performed for the prediction of the absorption maxima of azobenzene dyes. The entire set of 191 azobenzenes was divided into a training set of 150 azobenzenes and a test set of 41 azobenzenes according to Kennard and Stones algorithm. A seven-descriptor model, with squared correlation coefficient ($R^2$) of 0.8755 and standard error of estimation (s) of 14.476, was developed by applying stepwise multiple linear regression (MLR) analysis on the training set. The reliability of the proposed model was further illustrated using various evaluation techniques: leave-many-out crossvalidation procedure, randomization tests, and validation through the test set.

• 한국안전학회지
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• 제29권6호
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• pp.151-157
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• 2014

This study deals with the rear-end collision at roundabouts. The purpose of this study is to develop the accident models of rear-end collision in Korea. In pursuing the above, this study gives particular attention to developing the appropriate models using Poisson, negative binomial model, ZAM, multiple linear and nonlinear regression models, and statistical analysis tools. The main results are as follows. First, the Vuong statistics and overdispersion parameters indicate that ZIP is the most appropriate model among count data models. Second, RMSE, MPB, MAD and correlation coefficient tests show that the multiple nonlinear model is the most suitable to the rear-end collision data. Finally, such the independent variables as traffic volume, ratio of heavy vehicle, number of circulatory roadway lane, number of crosswalk and stop line are adopted in the optimal model.