• Journal of Preventive Medicine and Public Health
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• v.30 no.4 s.59
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• pp.852-869
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• 1997

This study was conducted to develop and evaluate the reliability and the validity of a questionnaire in order to determine the applicability as a screening tool for estimating environmental exposure and health effects related to air pollution. The questionnaire was developed with adopting some items of others such as ISAAC or ATS-DLD. And then we performed test-retest to 89 middle school students and their mothers at interval of three months. Cohen's Kappa values, weighted Kappa values, Spearman's correlation coefficients, and Pearson's correlation coefficients for each item were computed as reliability coefficients. The validity coefficients and validity coefficient bounds were also obtained by simply using these reliability coefficients. As results, Kappa ranged broadly from 0.10 to 0.61 of the items 'diet', $0.52\sim0.79$ of the environmental tobacco smoke, $0.39\sim0.44$ of the functional categories of surrounding environment, and $0.39\sim0.44$ of the using transportation systems; these items were regarded as confounding factors. For items related to health outcomes, Kappa ranged from -0.02 to 0.37 in the respiratory system of past medical history, and from 0.11 to 0.55 in the current health status. But Kappa of the others were over 0.60. In conclusion, if some items can be corrected or modified, the questionnaire developed in this study can be used as a tool for evaluating environmental exposure and health effects associated with air pollution.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.4
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• pp.235-241
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• 2014

A ground-based microwave scatterometer has an advantage for monitoring soil moisture content using multi-polarization, multi-frequencies and various incidence angles. In this paper, ground-based multi-frequency (L-, C-, and X-band) polarimetric scatterometer system capable of making observations every 10 min was used to monitor the soil moisture conditions in a corn field over an entire growth cycle. Measurements of volumetric soil moisture were obtained and their relationships to the backscatter observations were examined. Time series of soil moisture content was not corresponding with backscattering coefficient pattern over the whole growth stage, although it increased until early July (Day Of Year, DOY 160). We examined the relationship between the backscattering coefficients from each band and soil moisture content of the field. Backscattering coefficients for all bands were not correlated with soil moisture content when considered over the entire stage ($r{\leq}0.48$). However, L-band Horizontal transmit and Horizontal receive polarization (HH) had a good correlation with soil moisture ($r=0.85^{**}$) when LAI was lower than 2. Prediction equations for soil moisture were developed using the L-HH data. Relation between L-HH and soil moisture shows linear pattern and related with soil moisture content ($R^2=0.77$). Results from this study show that backscattering coefficients of microwave scatterometer appear to be effective to estimate soil moisture content in the field level.

• Journal of the Korean Society of Tobacco Science
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• v.3 no.1
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• pp.41-48
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• 1981

Dihaploid lines were derived from the anthers of the F, of single cross, "Va 115" x"SC 72" (Nicotiana tabacum L.). The path-analysis, correlation coefficient, and variation of characteristics among dihaploid families were evaluated. Dihaploid lines displayed much greater variation than their parents. The genetic correlation coefficient between yield and total alkaloids of dihaploids was significantly lower than that of conventional varieties and lines. In path-analysis which relates yield components to yield, number of leaves harvested and leaf width had a direct effect on yield. a direct effect on yield.

• Honam Mathematical Journal
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• v.28 no.3
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• pp.317-326
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• 2006

Based on the geometrical representation of a generalized intuitionistic fuzzy set, we take into account all three parameters describing generalized intuitionistic fuzzy set and propose new methods to calculate the correlation coefficient for generalized intuitionistic fuzzy sets by means of mathematical statistics.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.25-32
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• 2006

Purpose : To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. Materials and Methods : An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined In each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Results : Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and - 0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlation with clinical bone quality classification with correlation coefficients -0.506 significantly (p<0.05). Conclusion : This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.141-152
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• 1996

This study is an attempt to investigate the chemical components of precipitation and its variation according to surface wind. Precipitation samples were collected by an wet-only precipitation sampler during the period of October 1994 to September 1995 at Kyungsan in Korea. The results obtained in t체s study are summerized as follows. The annual average of precipitation pH is 5.0, the highest month of pH is July of 5.5, and the lowest month of pH is December of 4.4. The most frequent appearance is in the range of pH 5.0 to 5.5 and its rate is 56.8%, The order of ion concentration In precipitation is SO42->NO3->Cl- in case of anion and $Ca^{2+}$>$NH_4^{+}$>$Na^+$>$Mg^{2+}$ in case of cation. It is found from our analysis that the correlation coefficient among the precipitation pH and ion components is below r=0.3, while the correlation coefficient between $SO_4^{2-}$ and NO_3^{-}$, $Na^+$ and $Cl^+$ is above r=0.8, respectively. The mean pH of precipitation is 4.8 under the westerly wind and 5.2 under the easterly wind. The concentrations of anion and cation under the westerly wind are more than the concentrations under the easterly wind. In autumn, the concentration of Na+ and $Cl^+$ under the easterly wind are higher than the concentration under the westerly wind. The correlation coefficients between wind speed and pH, ion components show very low correlation of -0.41 r 0.2. But the present study show that the correlation coefficient between wind speed and pH of precipitation is positive and the correlation coefficients between wind speed and ion concentration is negative.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.15-20
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• 2001

This study investigated the condensation heat transfer coefficients of R-22, R-290 and R-600a inside horizontal tube. Heat transfer measurements were peformed for smooth tube with outside diameter of 12.7 mm Condensation temperatures and mass velocity were ranged from 308 K to 323 K and $51kg/\textrm{m}^2s$s to $250kg/\textrm{m}^2s$, respectively. The test results showed that the local condensation heat transfer coefficients increased as the mass flux increased, and also the effects of mass velocity on heat transfer coefficients of R-290 and R-600a were less than R-22. Average condensation heat transfer coefficients of natural refrigerants were superior to that of R-22. The present results had a good agreement with Haraguchi's correlation.

• Wind and Structures
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• v.34 no.1
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• pp.81-90
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• 2022

To better understand the vortex-induced vibration (VIV) characteristics of a 5:1 rectangular cylinder, the distribution of aerodynamic force and the non-dimensional power spectral density (PSD) of fluctuating pressure on the side surface were studied in different VIV development stages, and their differences in the stationary state and vibration stages were analyzed. The spanwise and streamwise correlations of surface pressures were studied, and the flow field structure partitions on the side surface were defined based on the streamwise correlation analysis. The results show that the variation tendencies of mean and root mean square (RMS) pressure coefficients are similar in different VIV development stages. The RMS values during amplitude growth are larger than those at peak amplitude, and the smallest RMS values are observed in the stationary state. The spanwise correlation coefficients of aerodynamic lifts increase with increase of the peak amplitude. However, for the lock-in region, the maximum spanwise correlation coefficient for aerodynamic lifts occurs in the VIV rising stage rather than in the peak amplitude stage, probably due to the interaction of vortex shedding force (VSF) and self-excited force (SEF). The streamwise correlation results show that the demarcation point positions between the recirculation region and the main vortex region remain almost constant in different VIV development stages, and the reattachment points gradually move to the tailing edge with increasing amplitude. This study provides a reference to estimate the demarcation point and reattachment point positions through streamwise correlation and phase angle analysis from wind tunnel tests.

• Journal of Korea Multimedia Society
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• v.8 no.12
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• pp.1631-1637
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• 2005

Based on the generalized Gaussian pdf of DCT coefficients of images, Hernandez et al. propose the ML test applied watermark decoder. For images with watermarks shaped by the visibility thresholds of DCT coefficients and the luminance masking of human visual system, they conclude that the ML test with an appropriately chosen parameter associated with the pdf of DCT coefficients outperforms the correlation based decoder. In this paper, the parameter is estimated using various methods including a novel one for watermarks shaped by the visibility thresholds of DCT coefficients and the luminance masking as Hernandez et al. did and with the contrast masking added, and its effect on performance is compared.

• Speech Sciences
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• v.9 no.3
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• pp.3-16
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• 2002

We examined some problems in speaker identification procedures: transformation of acoustic parameters into auditory scales, invalid measurement values, and comparability of spectral energy values across the frequency range. To resolve those problems, we analyzed the acoustic spectral energy of three Korean numbers produced by ten female students from narrow-band spectrograms at 19 proportional time points of each voiced segment. Then, cells of the first five spectral matrices were averaged to form a matrix model for each speaker. The correlation coefficients and sum of the absolute amplitude difference in each pair of the spectral models of the ten subjects were obtained. Also, some individual matrix models were compared to those of the same subject or the other subject with a similar spectral model. Results showed that in numbers '2' and '9' subjects could not be clearly distinguished from the others but in number '4' it shed some possibility of setting threshold values for speaker identification if we employed the coefficients and the sum of absolute difference. Further studies would be desirable on various combinations of the range of long-term average spectra and the degree of signal pre-emphasis.