• Nuclear Engineering and Technology
• /
• v.27 no.4
• /
• pp.491-502
• /
• 1995

In accurate prediction of cross-flow based on detailed knowledge of the velocity field in subchannels of a nuclear fuel assembly is of importance in nuclear fuel performance analysis. In this study, the low-Reynolds number k-$\varepsilon$ turbulence model has been adopted in too adjacent subchannels with cross-flow. The secondary flow is accurately estimated by the anisotropic algebraic Reynolds stress model. This model was numerically calculated by the finite element method and has been verified successfully through comparison with existing experimental data. Finally, with the numerical analysis of the velocity Held in such subchannel domain, an analytical correlation of the lateral loss coefficient is obtained to predict the cross-flow rate in subchannel analysis codes. The correlation is expressed as a function of the ratio of the lateral How velocity to the donor subchannel axial velocity, recipient channel Reynolds number and pitch-to-diameter.

• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.6
• /
• pp.579-589
• /
• 2007

Contrary to the conventional single-point measuring devices such as LDV, pitot-tube, hot-wire, etc., it would be possible to measure instantaneously 3-D flow fields with a stereoscopic PIV system. In this paper, we present an analysis algorithm for a stereoscopic PIV system using the normalized cross-correlation (NCC) and a 3-D calibration based reconstruction method. The evaluation method based on NCC is one of the most accurate correlation-based methods. We validated the developed algorithm through a benchmarking comparison with 3-D artificial SPIV images and calibration target images.

• Journal of Integrative Natural Science
• /
• v.8 no.3
• /
• pp.214-220
• /
• 2015

Cancer has emerged as one of the leading cause of deaths worldwide. A three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis was performed on a series of quinazoline-based anticancer agents. Purpose of the study is to understand the structural basis for their inhibitory activity. Comparative molecular field analysis (CoMFA) technique was employed to develop 3D-QSAR model. Ligand-based alignment scheme was used to generate a reliable CoMFA model. The model produced statistically significant results with a cross-validated correlation coefficient ($q^2$) of 0.589 and a non-cross-validated correlation coefficient ($r^2$) of 0.928. Model was further validated by bootstrapping and progressive scrambling analysis. This study could assist in the design of novel and more potent anticancer agents.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.12
• /
• pp.1004-1013
• /
• 2002

Turbulent carbon dioxide flows and cooling heat transfers under supercritical state in a straight duct with a square cross-section are numerically analyzed employing low Reynolds number $\kappa-\varepsilon$ model and algebraic stress model. The flow is assumed to be (quasi-incompressible. Predicted Nusselt number and friction factor are compared with the experimental data, Blasius correlation for friction factor and Dittus-Boelter correlation for Nusselt number. Computational results for the Fanning's friction factor agree well with the all Rohsenow and Choi's correlation, Liou and Hwang's experimental data and Blasius correlation. The results obtained by algebraic stress model agree more with the Liou and Hwang's experimental data, while the results obtained by low Reynolds number $\kappa-\varepsilon$ model agree more with Blasius correlation. In the computation of Nusselt number, Dittus-Boelter correlation can not exactly fit the computational results. Therefore we propose the new correlation$Nu=0.053Re^{0.73}Pr^{0.4}$for the turbulent cooling heat transfer of carbon dioxide under supercritical state.

• The Journal of the Acoustical Society of Korea
• /
• v.36 no.4
• /
• pp.279-284
• /
• 2017

The localization of sources has a numerous number of applications. To estimate the position of sources, the relative time delay between two or more received signals for the direct signal must be determined. Although the GCC (Generalized Cross-Correlation) method is the most popular technique, an approach based on CCA (Canonical Correlation Analysis) was also proposed for the TDE (Time Delay Estimation). In this paper, we propose a new adaptive algorithm based on CCA in order to utilized the sparsity in the eigenvector of CCA based time delay estimator. The proposed algorithm uses the eigenvector corresponding to the maximum eigenvalue with log-sum regularization in order to utilize the sparsity in the eigenvector. We have performed simulations for several SNR(signal to noise ratio)s, showing that the new CCA based algorithm can estimate the time delays more accurately than the conventional CCA and GCC based TDE algorithms.

• Journal of the military operations research society of Korea
• /
• v.33 no.2
• /
• pp.61-73
• /
• 2007

We examined technological forecasting of extended TFDEA(Technological Forecasting with Data Envelopment Analysis) and thereby apply the extended method to the technological forecasting problem of main battle tank. The TFDEA has the possibility of using comparatively inefficient DMUs(Decision Making Units) because it is based on DEA(Data Envelopment Analysis), which usually leads to multiple efficient DMUs. Therefore, TFDEA may result in incorrect technological forecasting. Instead of using the simple DEA, we incorporated the concept of Super-efficiency, Cross-efficiency, and CCCA(Constrained Canonical Correlation Analysis) into the TFDEA respectively, and applied each method to the case study of main battle tank using verifiable practical data sets. The comparative analysis shows that the use of CCCA with TFDEA results in very comparable prediction accuracies with respect to MAE(Mean Absolute Error), MSE(Mean Squared Error), and RMSE(Root Mean Squared Error) than using the concept of Super-efficiency and Cross-efficiency.

• Journal of the Korean Magnetic Resonance Society
• /
• v.10 no.1
• /
• pp.46-58
• /
• 2006

With a simple pulse sequence ($\pi/2$-{gradient, duration T}-acquisition) in solution NMR, detected signal has slowly grown up to percents of the equilibrium magnetization. The source of this unusual resurrection of dephased magnetization after a crushed gradient is cross-correlated effects of radiation damping and the distant dipolar field, which has been demonstrated by a numerical simulation and theoretical analysis.

• The Journal of Engineering Geology
• /
• v.29 no.3
• /
• pp.303-314
• /
• 2019

Surface permeability and shallow geological structures play significant roles in shaping the groundwater recharge of shallow aquifers. Surface permeability can be characterized by two concepts, intrinsic permeability and hydraulic conductivity, with the latter obtained from previous near-surface geological investigations. Here we propose a hydraulic equation via the cross-correlation analysis of the rainfall-groundwater levels using a regression equation that is based on the cross-correlation between the grain size distribution curve for unconsolidated sediments and the rainfall-groundwater levels measured in the Gyeongju area, Korea, and discuss its application by comparing these results to field-based aquifer test results. The maximum cross-correlation equation between the hydraulic conductivity derived from Zunker's observation equation in a sandy alluvial aquifer and the rainfall-groundwater levels increases as a natural logarithmic function with high correlation coefficients (0.95). A 2.83% difference between the field-based aquifer test and root mean square error is observed when this regression equation is applied to the other observation wells. Therefore, rainfall-groundwater level monitoring data as well as aquifer test are very useful in estimating hydraulic conductivity.

• Nuclear Engineering and Technology
• /
• v.52 no.2
• /
• pp.296-307
• /
• 2020

Permanent magnet sodium flowmeter (PMSF) have been used to measure the sodium flow in fast breeder reactors. Due to the effects of irradiation, thermal cycling, time lapse, etc., the magnetic flux density of the PMSF will decrease after being used in the reactor for a period of time. Therefore, it must be calibrated regularly. But some flowmeters that immersed in sodium cannot be removed for an off-line calibration, so the on-line calibration is required. However, the best online calibration accuracy of PMSF using cross-correlation analysis method was 2.0-level without considering the repeatability. In order to further improve this work, the operational principle of the transducer in PMSF is analyzed and the design principle of the transducer is proposed. The transducers were tested on the sodium flow loop to collect the experimental data. The signal characteristics are analyzed from the time and frequency domains, respectively. The cross-correlation analysis method based on biased estimation is adopted to obtain the flow rate. The verification experimental results showed that the measurement accuracy is 1.0-level when the flow velocity is above 0.5 m/s, and the measurement accuracy is 3.0-level when the flow velocity is in the range of 0.2 m/s to 0.5 m/s.

• The Journal of Korean Medicine
• /
• v.39 no.2
• /
• pp.80-91
• /
• 2018

Objectives: The purpose of this study was to investigate stress and health recognition in Korean medical student by gender. Methods: 393 Korean medical student participated in this study. They were surveyed demographic characteristics(gender, age, drinking, morning diet, health recognition and etc), medical stress scale, Maslachh burnout inventory, Korea acceptance and action, and Ego Resilience Scale. For statistical analysis, chi-square test, Student t-test, correlation analysis, and simple regression analysis has been used. Results: In Medical stress scale and ego resilience, it is not significant difference by gender. Female students were significantly higher than male students in Maslach burnout inventory(P=0.015). Male students were significantly higher than female students in Korea Acceptance and Action(P=0.002). Health recognition have negative correlation between medical stress and academic exhaustion, and positive correlation between psychological flexibility and ego resilience. Conclusions: Through these results, we need to further study and develop strategies to reduce stress according to gender in Korean medical college.