• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.119-125
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• 2003

An experiment study on pressure drop was carried out for both an adiabatic and a diabatic two-phase flow with pure refrigerants R134a and Rl23 and their mixtures as test fluids in a uniformly heated horizontal tube. The frictional pressure drop during flow boiling is predicted by using two models; the homogeneous model that assumes equal phase velocity and the separate flow model that allows a slip velocity between two phases. The measured frictional pressure drop was compared to a few available correlations. Homogeneous model considerally underpredicted the present data for mixture as well as pure component in the entire mass velocity ranges employed in the present study, while Friedel correlation was found to satisfactorily correlate the frictional pressure drop data as compared to other correlation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1049-1056
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• 2000

In this study, condensation heat transfer coefficients(HTCs) of 2 nonazeotropic refrigerant mixtures of HFC32/HFC134a and HFC134a/HCFC123 at various compositions were measured on a horizontal smooth tube. All data were taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling of 3~8K. Test results showed that HTCs of tested mixtures were 11.0~85.0% lower than the ideal values calculated by the mass fraction weighting of the pure components HTCs. Thermal resistance due to the diffusion vapor film was partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures. The measured data were compared against the predicted ones by Colburn and Drew\`s film model and a good agreement was observed.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.48-51
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• 2004

The light element candidates such as S, O, Si, and K are discussed for the reasonable compositions in the earth's core since the available data show density difference from pure iron core. These candidates are favored by the some evidences such as depletion in the crust and mantle, and lower eutectic temperature of Fe-FeS melt for sulfur. FeO phase for oxygen, lighter mass than sulfur and solubility in metallic phases for silicon, and partitioning in Fe-FeS melt for potassium. However, other problems such as short experimental data, initial compositions of these elements, and oxidation state during the formation of the earth should be solved simultaneously to confirm these light elements.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.334-336
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• 2003

Satellite and airborne hyperspectral sensor images are suitable for investigating the vegetation state in agricultural land. However, image data obtained by an optical sensor inevitably includes mixels caused by high altitude observation. Therefore, mixel analysis method, which estimates both the pure spectra and the coverage of endmembers simultaneously, is required in order to distinguish the qualitative spectral changes due to the chlorophyll quantity or crop variety, from the quantitative coverage change. In this paper, we apply our agricultural independent component analysis (ICA) model to an airborne hyperspectral sensor image, which includes noise and fluctuation of coverage, and estimate pure spectra and the mixture ratio of crop and soil in agricultural land simultaneously.

• Natural Product Sciences
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• v.13 no.2
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• pp.110-113
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• 2007

Five flavonoid derivatives, pinostrobin (1), pinocembrin (2), alpinetin (3), cardamonin (4) and boesenbergin A (5) were isolated from the rhizomes of Boesenbergia pandurata. All compounds were elucidated based on its spectroscopic data and by the comparison with the previous works. 2D NMR technique was used for the structure elucidation of boesenbergin A to complement the data reported previously. The extracts and pure compounds were screened for cytotoxic activity against HL-60 cancer cell lines (human promyelocytic leukemia). Cytotoxic screening showed most of the extracts and pure compounds isolated from the rhizomes of Boesenbergia pandurata were active against HL-60 cancer cell line. The chloroform extract and boesenbergin A showed the most potent cytotoxic activity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.2
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• pp.122-133
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• 2001

Pool boiling heat transfer coefficients(HTCs) of HFC32/HFC134a, HFC125/HFC134a, HFC32/HFC125 and HFC32/HFC125/HFC134a were measured on a horizontal smooth tube. The experimental apparatus was specially designed to simulate the real heat transfer tube with the use of the secondary fluid of water. Data were taken in the order of decreasing heat flux starting at 80kW/$m^2\; and\; ending\; at\; 5kW/m^2$ in the pool temperature at $7^{\circ}C$. Test results showed that HTCs of these mixtures were 11~38% lower than those of ideal HTCs calculated by a linear mixing rule with pure fluids、 HTCs. Experimental data were compared with Stephan & Korner, Thome, Schlunder, Thome & Shakir、s correlations only to find that those correlations were not satisfactory for all fluids. Hence, a new correlation based on the present data was proposed which could be applied even to the ternary mixture. The correlation predicts the degradation of HTCs of mixtures well, showing a mean deviation of less than 15% for all the mixture data.

• The Pure and Applied Mathematics
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• v.8 no.1
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• pp.47-51
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• 2001

We establish the global existence of nonnegative solutions to some reaction-diffusion equation for exponential nonlinearity for small initial data.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.3
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• pp.89-93
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• 2009

Purpose: To purpose of this study was the pure-tone audimetry changes to compare pre and post fogging after visual correction in normally hearing adults. Methods: The estimated that no ocular and audiolar disesases, we selected (male: 30, female: 20) in corrected visual acuity over the 1.0 eye. Pre and post fogging were measured using the pure-tone audimetry. Results: To compared fre and post fogging, fre fogging was higher than fre fogging. The take value were just about every kind of Hz but 200 Hz, respectively which were statistically significant (p<.05). Low Hz area in 250 and 500 Hz were 6.8${\pm}$8.4dBHL, 4.3${\pm}$6.6dBHL, there is not all the difference between any other area, 2000 Hz in the middle Hz area was 0.8${\pm}$4.5dBHL. Conclusions: The study presents different results of measurements in within normal limits. we thought that pure-tone thresholds to the pre and post fogging after refractive correction in normal adults and would be used basic data.

• Geophysics and Geophysical Exploration
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• v.25 no.4
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• pp.227-241
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• 2022

Full waveform inversion (FWI) in the field of seismic data processing is an inversion technique that is used to estimate the velocity model of the subsurface for oil and gas exploration. Recently, deep learning (DL) technology has been increasingly used for seismic data processing, and its combination with FWI has attracted remarkable research efforts. For example, DL-based data processing techniques have been utilized for preprocessing input data for FWI, enabling the direct implementation of FWI through DL technology. DL-based FWI can be divided into the following methods: pure data-based, physics-based neural network, encoder-decoder, reparameterized FWI, and physics-informed neural network. In this review, we describe the theory and characteristics of the methods by systematizing them in the order of advancements. In the early days of DL-based FWI, the DL model predicted the velocity model by preparing a large training data set to adopt faithfully the basic principles of data science and apply a pure data-based prediction model. The current research trend is to supplement the shortcomings of the pure data-based approach using the loss function consisting of seismic data or physical information from the wave equation itself in deep neural networks. Based on these developments, DL-based FWI has evolved to not require a large amount of learning data, alleviating the cycle-skipping problem, which is an intrinsic limitation of FWI, and reducing computation times dramatically. The value of DL-based FWI is expected to increase continually in the processing of seismic data.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.49-58
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• 2019

Major objective of the study are to analyze the trends of domestic research on pure play internet banks and to propose the future research directions of the ares. To achieve the objectives, this study first summarize the basic concepts and current status of pure play internet banks, establish analysis criteria, and analyze 56 papers based on the criteria. Major research results and future research directions are summarized as follows: non-empirical research should utilize mathematical/conceptual model rather than opinion/guidance, and empirical research should employ secondary data analysis method; in case of the individual level analysis, research on the bank personnel, and on use/outcome of customers should be performed; more organizational level studies should be performed; and in case of societal level research, impact of the pure play internet banks should be analyzed in depth.