• Journal of Astronomy and Space Sciences
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• v.30 no.3
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• pp.163-168
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• 2013

Parameters associated with solar minimum have been studied to relate them to solar activity at solar maximum so that one could possibly predict behaviors of an upcoming solar cycle. The number of active days has been known as a reliable indicator of solar activity around solar minimum. Active days are days with sunspots reported on the solar disk. In this work, we have explored the relationship between the sunspot numbers at solar maximum and the characteristics of the monthly number of active days. Specifically, we have statistically examined how the maximum monthly sunspot number of a given solar cycle is correlated with the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days for the corresponding solar cycle. We have calculated the linear correlation coefficient r and the Spearman rank-order correlation coefficient $r_s$ for data sets prepared under various conditions. Even though marginal correlations are found, they turn out to be insufficiently significant (r ~ 0.3). Nonetheless, we have confirmed that the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days is less steep when solar cycles belonging to the "Modern Maximum" are considered compared with rests of solar cycles. We conclude, therefore, that the slope of the linear relationship between monthly sunspot numbers and the monthly number of active days is indeed dependent on the solar activity at its maxima, but that this simple relationship should be insufficient as a valid method to predict the following solar activity amplitude.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.2
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• pp.61-71
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• 2023

The purpose of this study is to examine the relationship between POS, JR, and Innovation, and to explore the role of job psychological empowerment as a mediator in this relationship. A structured questionnaire was distributed to 25 companies in the petrochemical industry. PLS-SEM 4 was used to analyze the data of 100 valid responses. These findings suggest that employee empowerment (EMPOW) fully mediates the relationship between job resourcefulness (JR) and Innovation (INNOV). The total effect of JR on INNOV is also significant, with a beta coefficient of 0.234 and a t-value of 3.375. However, when the mediating influence of EMPOW is taken into account, the effect of JR on INNOV is no longer significant, with a beta coefficient of 0.100 and a t-value of 1.610. This suggests that EMPOW plays a key role in the relationship between JR and INNOV and that JR may not have a direct impact on Innovation. The study informs the development of interventions or strategies for promoting Innovation in organizations by identifying key factors that facilitate or inhibit the innovation process. The study further contributes to the development of new theories or models on the relationship between perceived organizational support, job resourcefulness, psychological empowerment, and Innovation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1199-1206
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• 2015

In this study, the exhaust gas of a diesel engine operating on biodiesel(BD) fuel(a mixture of diesel and soybean oil) was investigated for different fuel mixing ratios in the range of BD3 to BD100. The experiments were conducted using injection pressures of 400, 600, 800, 1000, and 1200 bar. The Pearson correlation coefficient and Spearman rank-order correlation coefficient were used to quantify the NOx and Soot emissions based on the fuel mixing ratio and injection pressure. Consequently, the Pearson correlation coefficient obtained for NOx and Soot emissions according to the mixing ratio and injection pressure was -0.811 and the corresponding Spearman rank-order correlation coefficient was -0.884, which indicated that the correlation of the NOx and Soot emissions was linear. Thus, the NOx and Soot have a trade-off relationship. Moreover, at each injection pressure, the Pearson correlation coefficient was a negative number, which indicated an inversely proportional relationship between NOx and Soot.

• Transactions on Electrical and Electronic Materials
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• v.8 no.2
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• pp.79-83
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• 2007

The implications of a theory of lubricated pad asperity wafer contact are traced through several fundamental areas of chemical-mechanical polishing. The hypothesized existence of a nanolubrication layer underlies a high accuracy model of polish rates. It also provides a quantitative explanation of a power law relationship between the coefficient of friction and a measure of pad surface flattening. The theory may further be useful for interpreting friction changes during polishing, and may explain why the coefficient of friction is sometimes observed to have a temperature or velocity dependence.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.546-549
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• 2007

When we deal with crisp data, it is common to find the correlation between variables. In this paper, we propose a method to calculate the correlation coefficient for intuitionistic fuzzy data, by adopting the concepts from the conventional statistics. The value of the correlation coefficient computed from our formula not only provides us the strength of the relationship of intuitionistic fuzzy sets, but also shows that the intuitionistic fuzzy sets are positively or negatively related.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.489-497
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• 2009

Most of existent blind watermarking methods in frequency domain use coefficient relationship to detect the watermark without original image. But the change in coefficient values occurred when the original image was attacked by lossy JPEG compression or noise addition. So robustness of watermark detection was weaken. In order to solve these problems, this paper presents a robust watermarking method, which enables multiple watermark insertion. Also, in order to reduce errors in the detected value of watermarks according to small changes in the coefficient relationship when detecting watermarks, it set the change guard value for variation of the coefficients. The experimental results show that the proposed method has good image quality and is robust to various attacks such as the JPEG lossy compression, noise addition, etc.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.226-233
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• 1998

In this paper, an experimental study was performed to investigate the speed ratio-torque-thrust characteristics for metal belt CVT. It is observed from the experimental results that nondimensional secondary thrust force follows with the existing theoretical formula with ${\mu}$=0.09~0.12 depending on the torque and the speed ratio. In order to represent these characteristics, an effective friction coefficient was introduced. Also, the slip characteristics between the belt and the pulley were investigated experimentally and traction coefficients at gross slip were obtained for various speed ratios. Using the traction coefficients and the effective friction coefficients, an improved formula for the secondary thrust force was suggested assuming that thrust force is the summation of the thrust of pseudo inactive arc and the thrust of pseudo active arc. The effective friction coefficient and the improved formula for the speed ratio-torque-thrust relationship suggested in this work can be used to obtain the appropriate secondary thrust.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.4
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• pp.28-36
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• 2002

The main purpose of this study was to estimate a new regression model to explain the relationship between urban forest and air temperature in summer, 2001. This study consists of two parts: correlation coefficient analysis and regression analysis. According to correlation coefficient analysis, thermal infra-red radiations of the major land use categories found significant difference in each category. However there were no significant relationship between the data (thermal infra-red radiation and NDVI) derived from Landsat-7 ETM+ image and air temperature at Automatic Weather Stations(AWSs). After estimating various regression models for summer air temperature, the final models were chosen. The final regression models consisted of two variables such as forest m and traffic facilities area. The regression models explained over 78% of the variability in air temperatures. The regression models with variables of forest area and traffic facilities area showed that the coefficient of the first variable was even more significant than the second one. However, the negative impact of the traffic facilities area was slightly greater than the positive impact of the forest area. Consequently, the effects of forest area and traffic facilities area were apparent to explain summer air temperature in Seoul. Therefore two policies have the most important implications to mitigate the summer air temperature in Seoul: to expand and to conserve the urban forest; and to change the Oafnc facilities'characteristics. The results from this study are expected to be useful not merely in informing the public that urban forest mitigates summer air temperahne, but in urging the necessity of budgets for trees and managing urban forests. It is recommended that field swey of summer air temperature be Performed for the vadidation of the models. The main purpose of this study was to estimate a new regression model to explain the relationship between urban forest and air temperature in summer, 2001. This study consists of two parts: correlation coefficient analysis and regression analysis. According to correlation coefficient analysis, thermal infra-red radiations of the major land use categories found significant difference in each category. However there were no significant relationship between the data (thermal infra-red radiation and NDVI) derived from Landsat-7 ETM+ image and air temperature at Automatic Weather Stations(AWSs). After estimating various regression models for summer air temperature, the final models were chosen. The final regression models consisted of two variables such as forest m and traffic facilities area. The regression models explained over 78% of the variability in air temperatures. The regression models with variables of forest area and traffic facilities area showed that the coefficient of the first variable was even more significant than the second one. However, the negative impact of the traffic facilities area was slightly greater than the positive impact of the forest area. Consequently, the effects of forest area and traffic facilities area were apparent to explain summer air temperature in Seoul. Therefore two policies have the most important implications to mitigate the summer air temperature in Seoul: to expand and to conserve the urban forest; and to change the traffic facilities'characteristics. The results from this study are expected to be useful not merely in informing the public that urban forest mitigates summer air temperature, but in urging the necessity of budgets for trees and managing urban forests. It is recommended that field survey of summer air temperature be Performed for the vadidation of the models.

• Journal of the Korean Geosynthetics Society
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• v.19 no.2
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• pp.1-11
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• 2020

The lateral bearing characteristics of large diameter drilled shaft depend greatly on the stiffness of the pile, horizontal subgrade reaction of adjacent ground. In particular, the empirical evaluation results of the horizontal subgrade reaction coefficient which are widely used in pile design are very important factors in evaluating the lateral bearing capacity of drilled shaft because the difference in bearing capacity depends on the estimated result. Nevertheless, the evaluation of the horizontal subgrade reaction coefficient on the large diameter drilled shaft is insufficient. In addition, although the range of influence and the location of the maximum moment which is the weaken zone on the pile may be correlated and relationship of these are major consideration in determining the reinforced zone of drilled shaft, the previous studies have not been evaluated it. In this study, the field test and nonlinear analysis of large diameter drilled shaft were performed to evaluate the horizontal subgrade reaction coefficient and to investigate the relationship between the influence range 1/β of the pile and the location of the maximum moment z_m. In the result, the lateral bearing capacity of drilled shaft showed a difference in results by about 190% according to the empirical equation on the horizontal subgrade reaction coefficient. And the relationship between the influence range of the pile and the location of the maximum moment was evaluated as a linear relationship depending on the soil density.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.537-544
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• 2002

Deformations of clays continue beyond the end of primary consolidation: this is secondary consolidation. Mesri(1973) have shown that C $\_$a/' is related to the natural water content W$\_$n/. For clays, C $\_$a/' is approximately equal to 0.01 W $\_$n/. And the ratio C $\_$ae// C $\_$c/ is approximately equal to 0.04. In this study, coefficient of secondary compression was analyzed by the consolidation tests datas in the 3 sites. In conclusion, coefficient of secondary compression was similar to Mesri's suggestions.