• Nuclear Engineering and Technology
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• v.34 no.4
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• pp.269-285
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• 2002

Water heat transfer experiments were carried out in a uniformly heated annulus with a wide range of pressure conditions. The local heat transfer coefficients for saturated water (low boiling have been measured just before the occurrence of the critical heat flux (CHF) along the length of the heated section. The trends of the measured heat transfer coefficients were quite different from the conventional understanding for the heat transfer of saturated flow boiling. This discrepancy was explained from the nucleate boiling in the liquid film of annular flow under high heat flux conditions. The well-known correlations were compared with the measured heat transfer coefficients. The Shah and Kandlikar correlations gave better prediction than the Chen correlation. However, the modified Chen correlation proposed in the present work showed the best agreement with the present data among correlations examined .

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1275-1283
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• 2006

Condensation heat transfer coefficients in a 7.92 mm inside diameter copper smooth tube were obtained experimentally for R22, R134a, and R410A. Working conditions were in the range of $30-40^{\circ}C$ condensation temperature, $95-410 kg/m^2s$ mass flux, and 0.15-0.85 vapor quality. The experimental data were compared with the eight existing correlations for an annular flow regime. Based on the heat-momentum analogy, a condensation heat transfer coefficients correlation for the annular flow regime was developed. The Breber et al. flow regime map was used to discern flow pattern and the Muller-Steinhagen & Heck pressure drop correlation was used for the term of the proposed correlation. The proposed correlation provided the best predicted performance compared to the eight existing correlations and its root mean square deviation was less than 8.7%.

• Communications for Statistical Applications and Methods
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• v.29 no.6
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• pp.655-664
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• 2022

On the motivation by an integrative study of multi-omics data, we are interested in estimating the structure of the sparse cross correlation matrix of two high-dimensional random vectors. We rewrite the problem as a multiple testing problem and propose a new method to estimate the sparse structure of the cross correlation matrix. To do so, we test the correlation coefficients simultaneously and threshold the correlation coefficients by controlling FRD at a predetermined level α. Further, we apply the proposed method and an alternative adaptive thresholding procedure by Cai and Liu (2016) to the integrative analysis of the protein expression data (X) and the mRNA expression data (Y) in TCGA breast cancer cohort. By varying the FDR level α, we show that the new procedure is consistently more efficient in estimating the sparse structure of cross correlation matrix than the alternative one.

• Child Health Nursing Research
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• v.15 no.3
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• pp.314-324
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• 2009

Purpose: This study was done to test the reliability and validity of the Korean parent as a teacher (KPAAT) inventory for a group of parents of preschoolers. Methods: For this methodological study with 187parents were recruited from October to December, 2004 using convenience sampling. Self-report questionnaires measured level of child-rearing attitude. Internal consistency reliability was assessed with Cronbach's alpha coefficients. Construct validity of KPAAT inventory was analyzed using item analyses and factor analysis. Statistical analysis was done using SPSS Program Version 14.0. Results: The Cronbach's alpha coefficient for the KPAAT inventory was 0.881. For item analyses, inter-item correlation coefficients were -0.029${\sim}$0.781. Corrected item-total correlation coefficients were 0.012-0.737. Item-to"subscale correlation coefficients ranged from 0.509 to 0.817. Subscale-to-total correlation coefficients were 0.965, 0.711, respectively. Orthogonal varimax rotation of the 85 items in 16 areas of the KPAAT inventory, showed two factors, positive parenting attitude and negative parenting attitude. These two factors explained 48.2% of the total variance. Conclusion: In the original KPAAT inventory six factors were identified through factor analysis, however, in this study only two factors were extracted. Whereas, internal consistency reliability was within an acceptable range, these results suggest additional studies are needed to improve the validity of the KPAAT inventory.

• Plant Resources
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• v.6 no.2
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• pp.134-139
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• 2003

This study was conducted to investigate the relationships between yearly variations of meteorological elements and yearly variations of productivity in rice. In addition, correlation coefficients among yield and yield components were used to find out the relationships between meteorological elements and productivity. Yearly variation of the mean air temperature in May was large with coefficients of variation(C.V.) of 25.0%, but the variation of the duration of sunshine in May were relative small. No. of panicles per hill and 1,000 grains wt. of brown rice were great with C.V. of 21.1, 19.7%, respectively, brown rice yield show more or less C.V. of 5.5% and milled rice show still less variation. Correlation coefficients between temperatures in period of cultivation from May and yield were positive correlations. Correlation Coefficients between precipitation in period of cultivation from Sep. to Oct. and yield are positive correlations. Correlation coefficients amount the panicle length, no. of panicles, no. of spikelets, ratio of ripened grains, 1,000 grains wt. of brown rice, milled rice yield, brown rice yield and milled rice yield were positively significant at the level of 1 %, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.91-97
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• 2013

The input parameters of scattering models for computing the backscattering coefficients of earth terrains are mainly soil moisture and surface roughness. The backscattering coefficients of soil surfaces are more sensitive to surface roughness than soil moisture. In this study, we propose a precise measurement method for roughness parameters and analyze measurement errors. We measured surface roughness using a pin-board profiler(1 m, 0.5 cm interval) and a laser profiler(1 m, 0.25 cm interval). The measurement differences between two profilers in an average sense are 0.097 cm for root-mean-square (RMS) height and 1.828 cm for correlation length. The analysis of the correlation functions and relative errors shows that the laser measurements are more stable than the pin-board measurements. The differences of the calculated backscattering coefficients using a surface scattering model between pin-board and laser profiler measurements are less than 1 dB.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.05a
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• pp.26-33
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• 2000

This study was conducted to investigate the relationships between yearly variations of elimatic elements and yearly variations of productivity in potato. In addition, correlation coefficients among yield and yield components were estimated. The data of yield and yield components were investigated for 9 years from 1987 to 1995. The meteorological data what gathered at the Goheung Weather Station for the same period of crop growing season were used to find out the relationships between climatic elements and crop productivity. Yearly variation of the daily minimum temperature in March and April were large with coefficients of variation (C.V.) of 126.0%, 368%, respectively, but the variation of the daily mean and maximum temperature in May and June were relative small. Stem length and number of stem show more C.V. of 9.3%, 14.3%, respectively, but the variation of the yield was relative small with 3.7%. Correlation coefficients between the amount of precipitation in April and yield, yield and daily mean temperature in June were negatively significant at the level of 5, 1 %, respectively. Correlation coefficients between the growth habits and yield are positively significant at the level of 5, 1 %, respectively. Simple linear regression equations by the least square method are estimated for stem length (Yl) and the precipitation in April(X) as Y,=82.47-0.11x (R2=0.3959), and for yield(Y2) and the precipitation in April(X) as Y,=2003.61-0.94X (R2=0.5418).

• Speech Sciences
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• v.10 no.4
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• pp.189-200
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• 2003

The objective of this study was to examine two new parameters by which we could screen people with malignant vocal folds. The new parameters were the difference sums and Pearson correlation coefficients between adjacent pairs of intensity level matrices of narrow-band spectra. Audio files from the Korean Disordered Speech Database were analyzed by Praat, a speech analysis software, to obtain matrices of 400 intensity levels at 16 time points of each sustained vowel spectra. We limited our study to 12 normal subjects and 20 patients with malignant vocal folds who recorded at least three Korean vowels at a sound-proofed booth in Busan National University Hospital. Results indicated that the average coefficients of the abnormal subjects were much lower than those of the normal subjects while the average difference sums of the patients were much higher than those of the normal ones. Also, we found that the degree of the malignancy of the vocal folds was related to the coefficients and sums. However, some subjects at the initial stages of cancerous vocal folds yielded almost comparable coefficients and difference sums to those of the normal speakers. Further studies on larger databases will be desirable to set certain criteria or threshold levels for screening people with vocal fold diseases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.633-641
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• 1999

Experiments were carried out to investigate the condensation heat transfer characteristics for R22 and its alternatives, R407C (R32/125/134a, 23/25/52wt%) and R410A (R32/125, 50/50wt%). A concentric tube heat exchanger was made to conduct condensation heat transfer tests. Mass flux and saturation temperature of refrigerants at the test section inlet were varied to get the corresponding heat transfer coefficients. Serial and parallel input of secondary fluid (water) were applied to the test subsections. Compared with existing correlations of condensation heat transfer, experimental heat transfer coefficients obtained in this study were generally higher than the predicted values, and mean absolute deviations from several correlations were shown. Wall subcooling was introduced to get a new correlation for condensation heat transfer coefficients by modifying Shah's equation. The RMS deviation of the measured heat transfer coefficients from the new correlation in this study for R22 is 9.9% and that for R407C and R410A are 10.2% and 14.6%, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.3
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• pp.183-190
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• 1993

For the efficient control of photochemical smog materials, the researches on the change patterns of photochemical smog precursors are indispensable. In this study, a time-series analysis was performed for the auto-monitoring data of Kwanghwamun and Jamsil stations in 1990, and the change patterns of photochemical smog materials were studied. Especially, auto-correlation coefficients were analyzed to investigate the cyclic characteristics of pollutants in question and cross-correlation coefficients to investigate the correlations between pollutants adjusted for time lag and between $O_3$ and meteorological factors. Results of researches are as follows: First, in the case of NO and $NO_2$ intimately related to human activities, 12-hour cycle was prevalent. But $O_3$ showed 24-hour cycle. Second, NO showed a relatively high correlation with $O_3$ and usually developed into $O_3$ 5 to 7 hours later. Third, temperature, insolation intensity, and wind speed showed a positive correlation with $O_3$ while relative humidity a negative correlation.