• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.57.1-57.1
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• 2014

We present results of our investigation of intrinsic brightness temperatures of compact radio jets at radio frequencies. The intrinsic brightness temperatures of about 100 compact radio jets at 2, 5, 8, 15, and 86 GHz are estimated based on large VLBI surveys conducted in 2001-2003 (or in 1996 for the 5 GHz sample). The multi-freqeuncy intrinsic brightness temperatures of the sample of the jets are determined with a statistical method relating the observed brightness temperatures with the maximal apparent jet speed, assuming one representative intrinsic brightness temperature for the sample at each observing frequency. With investigating the observed brightness temperatures at 15 GHz in multiple epochs, we found that the determination of the intrinsc brightness temperature for our sample is affected by variability of individual jets in flux density at the time scales of a few years. This implies an importance of contemporaneity of the multi-frequency VLBI observations for the statistical method. Since our analysis is based on the VLBI observations conducted in 2001-2003, the results are less affected by the flux density variability. We found that the intrinsic brightness temperature $T_0$ increases as $T_0{\propto}{\nu}^{\epsilon}$ with ${\epsilon}{\approx}0.7$ below a critical frequency ${\nu}_c{\approx}10GHz$ where energy losses begin to dominate the emission, and above the critical frequency, $T_0$ decreases with ${\epsilon}{\approx}-1.2$ supporting for the decelerating jet model.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1422-1436
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• 1997

Numerical investigations were conducted to study the convective phenomena of an initially stably stratified salt water solution with lateral heating in a uniformly rotating annulus. The method of investigation is the finite difference analysis of the basic conservation equation for an axisymmetric, unsteady, double-diffusive convection and calculation is made for R $a_{\eta}$=2*10$^{5}$ and Ta=10$^{7}$ ~ 2.5*10$^{8}$ . Formation of layered flow structure, merging process of layers, the corresponding temperature and concentration distributions, Nu variation with time are examined. Numerical results show that in each layer, the temperature profile looks 'S'-shaped and the concentration profile is uniform due to the convective mixing. At the interface between adjacent layers, the temperature changes smoothly but the concentration changes rapidly. As the effect of the rotation increases, the generation of rolls at hot wall, the formation and merging of layers are delayed. The average Nu shows the trend of conduction heat transferees the effect of the rotation increases.n increases.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2002.11a
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• pp.147-147
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• 2002

The slowly growing microaerophilic Helicobacter strains were isolated from the fecal pallets of 2 BALB/cA-Hfh11$\^$nu/ mice with rectal prolapse. The rectums of these mice protruded approximately 2 to 3 mm from the anus and varied in color from pale pink to deep red. Histopathologically, chronic proliferative colitis and proctitis were observed. The epithelium were hyperplastic and lymphocytes infiltrated markedly in mucosa and submucosa. Our isolated bactrial strains were characterized by morphological, physiological, molecular methods and special staining, and they were found to be Helicobacter hepaticus. We could not find any other pathogens from both mice. These results demonstrate that this organism may be a pathogen of the inflammatory large bowel disease in immunodeficent mice.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.109-116
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• 2018

$Eu_2(SO_4)_3$ was synthesized by chemical precipitation method and the crystal structure was determined by Rietveld analysis. The compound crystallizes in monoclinic space group C2/c. In the air environment, $Eu_2(SO_4)_3$ is stable up to $670^{\circ}C$. The sample of $Eu_2(SO_4)_3$ was examined by Raman, Fourier-transform infrared absorption and luminescence spectroscopy methods. The low site symmetry of $SO_4$ tetrahedra results in the appearance of the IR inactive ${\nu}_1$ mode around $1000cm^{-1}$ and ${\nu}_2$ modes below $500cm^{-1}$. The band intensities redistribution in the luminescent spectra of $Eu^{3+}$ ions is analyzed in terms of the peculiarities of its local environment.

• International journal of advanced smart convergence
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• v.8 no.1
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• pp.184-195
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• 2019

This study investigates the hair restoration efficacy of selected radish saponin extracts on nude mice. Nude mice genetically predisposed to pattern balding were used in this study. Our study revealed the underlying mechanism of stimulating hair growth in athymic nude mice by repair the nu/nu follicular keratin differentiation defect. Thus, the topical application of radish saponin may represent a novel strategy for the management and therapy of certain forms of alopecia. The term of hair density of PEE treated nude mice were significantly increase as compared with of control nude mice. Histological observation of skin sample showed no hair follicle or only distorted hair follicles were observed in the control samples, in contrast, by the PEE treatment groups showed a fully formed and increased the number of hair follicles up to three times higher than that of control group in terms of the number of hair follicles in nude mouse skin.PEE treated mice the number of BrdU-labeled keratinocytes per anagen follicle increased significantly, especially in the follicular bulbs and outer root sheath compared with the control mice. Moreover, PEE-treated nude mice also exhibited a significant increase in the number of BrdU-labeled epidermal keratinocyte proliferation.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.330-338
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• 2023

In this study, impacts of an enhanced-moderation Fuel Assembly (FA) named Truly Optimized PWR (TOP) lattice, which is modified based on the standard 17 × 17 PWR FA, are investigated in a natural circulation Soluble-Boron-Free (SBF) Small Modular Reactor (SMR). Two different TOP lattice designs are considered for the analysis; one is with 1.26 cm pin pitch and 0.38 cm fuel pellet radius, and the other is with 1.40 cm pin pitch and 0.41 cm fuel pellet radius. The NuScale core design is utilized as the base model and assumed to be successfully converted to an SBF core. The analysis is performed following the primary coolant circulation loop, and the reactor is modelled as a single channel for thermal-hydraulic analyses. It is assumed that the ratio of the core pressure drop to the total system pressure drop is around 0.3. The results showed that the reactor power could be increased by 2.5% and 9.8% utilizing 1.26/0.38 cm and 1.40/0.41 cm TOP designs, respectively, under the identical coolant inlet and outlet temperatures as the constraints.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2125-2138
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• 2023

The printed circuit heat exchanger (PCHE) with airfoil fins has the benefits of high compactness, high efficiency and superior heat transfer performance. A novel multi-objective optimization approach is presented to design the airfoil fin PCHE in this paper. Three optimization design variables (the vertical number, the horizontal number and the staggered number) are obtained by means of dimensionless airfoil fin arrangement parameters. And the optimization objective is to maximize the Nusselt number (Nu) and minimize the Fanning friction factor (f). Firstly, in order to investigate the impact of design variables on the thermal-hydraulic performance, a parametric study via the design of experiments is proposed. Subsequently, the relationships between three optimization design variables and two objective functions (Nu and f) are characterized by an improved particle swarm optimization-backpropagation artificial neural network. Finally, a multi-objective optimization is used to construct the Pareto optimal front, in which the non-dominated sorting genetic algorithm II is used. The comprehensive performance is found to be the best when the airfoil fins are completely staggered arrangement. And the best compromise solution based on the TOPSIS method is identified as the optimal solution, which can achieve the requirement of high heat transfer performance and low flow resistance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.32.2-32.2
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• 2018

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.777-782
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• 2013

In order to further reduce the sulfur content in liquid hydrocarbon fuels, a desulfurization process by adsorption for removing dimethyl sulfide (DMS) and propylmercaptan (PM) was investigated. Bentonite adsorbents modified by $CuCl_2$ for the desulfurization of model oil was investigated. The results indicated that the modified bentonite adsorbents were effective for adsorption of DMS and PM. The bentonite adsorbents were characterized by X-ray diffraction (XRD) and thermal analysis (TGA). The acidity was measured by FT-IR spectroscopy. Several factors that influence the desulfurization capability, including loading and calcination temperature, were studied. The maximum sulfur adsorption capacity was obtained at a Cu(II) loading of 15 wt %, and the optimum calcination temperature was $150^{\circ}C$. Spectral shifts of the ${\nu}$(C-S) and ${\nu}$(Cu-S) vibrations of the complex compound obtained by the reaction of $CuCl_2$ and DMS were measured with the Raman spectrum. On the basis of complex adsorption reaction and hybrid orbital theory, the adsorption on modified bentonite occurred via multilayer intermolecular forces and S-M (${\sigma}$) bonds.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.116-119
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• 2010

Adsorption structures of the self-assembled thin films of $\alpha$-cyano-4-hydroxycinnamic acid (CHCA) anchoring on $TiO_2$ surfaces have been studied by using temperature-dependent diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy. From the presence of the strong $\nu(COO^-)$ band at ~1390 $cm^{-1}$ along with the disappearance of the OH bands in the carboxylic acid group in the DRIFT spectra at room temperature, CHCA appeared to adsorb onto $TiO_2$ surfaces as a carboxylate form. The absence of the out-of-plane benzene ring modes of CHCA in the DRIFT spectra suggests a rather vertical orientation of CHCA on $TiO_2$. Above ~220$ ^{\circ}C$, CHCA seemed to start to thermally degrade on $TiO_2$ surfaces referring from the disappearance of most vibrational modes in the DRIFT spectra, whereas the $\nu$(C ≡ N) bands were found to remain relatively conspicuous as the temperature increased even up to ~460$^{\circ}C$.