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Search Results: 1 - 10 of 30573 matches for " Dae Ho Lee "
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Generic Lightlike Submanifolds of an Indefinite Cosymplectic Manifold
Dae Ho Jin,Jae Won Lee
Mathematical Problems in Engineering , 2011, DOI: 10.1155/2011/610986
Abstract: Lightlike geometry has its applications in general relativity, particularly in black hole theory. Indeed, it is known that lightlike hypersurfaces are examples of physical models of Killing horizons in general relativity (Galloway, 2007). In this paper, we introduce the definition of generic lightlike submanifolds of an indefinite cosymplectic manifold. We investigate new results on a class of generic lightlike submanifolds of an indefinite cosymplectic manifold .
A Basic Inequality for the Tanaka-Webster Connection
Dae Ho Jin,Jae Won Lee
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/231416
Abstract: For submanifolds tangent to the structure vector field in Sasakian space forms, we establish a Chen's basic inequality between the main intrinsic invariants of the submanifold (namely, its pseudosectional curvature and pseudosectional curvature on one side) and the main extrinsic invariant (namely, squared pseudomean curvature on the other side) with respect to the Tanaka-Webster connection. Moreover, involving the pseudo-Ricci curvature and the squared pseudo-mean curvature, we obtain a basic inequality for submanifolds of a Sasakian space form tangent to the structure vector field in terms of the Tanaka-Webster connection.
Constancy of $φ-$holomorphic scetional curvature in generalized $g.f.f-$manifolds
Jae Won Lee,Dae Ho Jin
Mathematics , 2011,
Abstract: Tanno [6] provided an algebraic characterization in an almost Hermitian manifold to reduce to a space of constant holomorphic sectional curvature, which he later extended for the Sasakian manifolds as well. In this present paper, we generalize the same characterization in generalized $g.f.f-$manifolds.
Perspective Projection Algorithm Enabling Mobile Device’s Indoor Positioning  [PDF]
Seo Woo Han, Yun Jung Lee, Ji Hyeok Yun, Chang Yong Han, Dae Ho Lee, Doug Young Suh
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.61017
Abstract:
In order to improve the user’s satisfaction with the augmented reality (AR) technology and the accuracy of the service, it is important to obtain the exact position of the user. Frequently used techniques for finding outdoors locations is the global positioning system (GPS), which is less accurate indoors. Therefore, an indoor position is measured by comparing the reception level about access point (AP) signal of wireless fidelity (Wi-Fi) or using bluetooth low energy (BLE) tags. However, Wi-Fi and Bluetooth require additional hardware installation. In this paper, the proposed method of estimating the user’s position uses an indoor image and indoor coordinate map without additional hardware installation. The indoor image has several feature points extracted from fixed objects. By matching the feature points with the feature points of the user image, we can obtain the position of the user on the Indoor map by obtaining six or more pixel coordinates from the user image and solving the solution using the perspective projection formula. The experimental results show that the user position can be obtained more accurately in the indoor environment by using only the software without additional hardware installation.
The Frequency and Clinical Significance of Sister Chromatid Exchange in the Lymphocyte of Gastric Cancer Patient Exposed to Hypoxia
Dae-Kwang Kim,Jae-Ho Lee,In-Ho Kim,Dae-Kyu Song
Cancer and Clinical Oncology , 2012, DOI: 10.5539/cco.v1n1p102
Abstract: The frequency of sister chromatid exchange (SCE) in patients with gastric cancer is significantly higher than that in normal individuals; however, their characteristics have not been studied. In present study, we analyzed the correlation between the cytogenetic instability of gastric cancer patients’ peripheral lymphocytes with or without hypoxia and the characteristics of gastric cancer patients. The primary lymphocyte cultures obtained from blood samples of 40 healthy donors and 69 patients with gastric cancer were examined using SCE. The average of SCE frequency in gastric cancer was 5.91 ± 2.03/cell and the SCE phenotype was not associated with gender, tumor grade, Lauren classification, and H.pylori infection. Hypoxia increased the SCE frequency as compared with normoxia, in both the control and gastric cancer lymphocyte cultures (P < 0.001). The hypoxic effect in gastric cancer was not associated with gender, tumor grade, Lauren classification, and H.pylori infection. In conclusion, hypoxia did not facilitate an increase of SCE in the lymphocytes of the gastric cancer.
Whitening Effect of Storage Protein 2 from Silkworm Hemolymph  [PDF]
Z-Hun Kim, Jung Wook Hwang, Joon Ho Lee, Hojin Kim, Dae-Seog Lim, Sangjin Kang, Heui Sam Lee, Yong-Soo Choi
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.59089
Abstract:

This study investigated the effects of silkworm hemolymph-derived storage protein 2 (SP2) on the whitening process in mouse B16F1 melanoma cells. After the cells were treated with various concentrations of SP2 (0.1 - 1.0 mg/mL), cytotoxicity, melanin contents, and differences in mRNA and protein expression associated with melanogenesis were observed. No cytotoxicity was observed when cells were treated with SP2, even with increased SP2 concentrations of up to 2.0 mg/mL. When treated with various SP2 concentrations in the cells, the protein and mRNA expression of tyrosinase were dose-dependently decreased, respectively, and inhibition of tyrosinase was further increased by 50.0% with increasing SP2 concentration of 1.0 mg/mL. Expression mRNAs coding tyrosinase related protein-1 and protein-2 (TRP-1 and TRP-2) was also significantly decreased in a dose dependent manner. When measuring the melanin content in melanoma cells, SP2 at 1 mg/mL inhibited melanin synthesis by 73.5% compared with non-treated cells. The inhibitory effect was 2.8-fold higher than that obtained using arbutin as a positive control. This study demonstrates that SP2, as a whitening material, is capable of suppressing melanin synthesis through the downregulation of proteins and genes in the melanin biosynthesis pathway.

Folding machineries displayed on a cation-exchanger for the concerted refolding of cysteine- or proline-rich proteins
Dae-Hee Lee, Sung-Gun Kim, Dae-Hyuk Kweon, Jin-Ho Seo
BMC Biotechnology , 2009, DOI: 10.1186/1472-6750-9-27
Abstract: We have generated refolding-facilitating media immobilized with three folding machineries, mini-chaperone (a monomeric apical domain consisting of residues 191–345 of GroEL) and two foldases (DsbA and human peptidyl-prolyl cis-trans isomerase) by mimicking oxidative refolding chromatography. For efficient and simple purification and immobilization simultaneously, folding machineries were fused with the positively-charged consecutive 10-arginine tag at their C-terminal. The immobilized folding machineries were fully functional when assayed in a batch mode. When the refolding-facilitating matrices were applied to the refolding of denatured and reduced RNase A and CHMO, both of which contain many cysteine and proline residues, RNase A and CHMO were recovered in 73% and 53% yield of soluble protein with full enzyme activity, respectively.The refolding-facilitating media presented here could be a cost-efficient platform and should be applicable to refold a wide range of E. coli inclusion bodies in high yield with biological function.Escherichia coli retains its dominant position as the first choice of host for the high-throughput production of proteins of therapeutic or commercial interest because of rapid biomass accumulation, well-established genetic manipulation methods and simple process scale-up [1,2]. However, a major disadvantage derived from the intrinsic properties of E. coli is the frequent formation of an inclusion body, a dense aggregate of misfolded polypeptides [3]. Refolding the inclusion bodies into the native conformation might be straightforward if an efficient refolding scheme is established. There are a variety of conventional methodologies for refolding recombinant proteins from inclusion bodies, which contains simple dilution, dialysis and chromatographic refolding methods. Dilution is the simplest and most widely used technique and involves refolding initiation by reducing the denaturant concentration. However, the target product in dilution refold
Anti-TNF-α Activity of Portulaca oleracea in Vascular Endothelial Cells
An Sook Lee,Jin Sook Kim,Yun Jung Lee,Dae Gill Kang,Ho Sub Lee
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13055628
Abstract: Vascular inflammation plays a key role in the pathogenesis and progression of atherosclerosis, a main complication of diabetes. The present study investigated whether an aqueous extract of Portulaca oleracea (AP) prevents the TNF-α-induced vascular inflammatory process in the human umbilical vein endothelial cell (HUVEC). The stimulation of TNF-α induced overexpression of adhesion molecules affects vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1 and E-selectin for example. However, AP significantly suppressed TNF-α-induced over-expression of these adhesion molecules in a dose-dependent manner. In addition, pretreatment with AP dose-dependently reduced an increase of the adhesion of HL-60 cells to TNF-α-induced HUVEC. Furthermore, we observed that stimulation of TNF-α significantly increased intracellular reactive oxygen species (ROS) production. However, pretreatment with AP markedly blocked TNF-α-induced ROS production in a dose-dependent manner. The western blot and immunofluorescence analysis showed that AP inhibited the translocation of p65 NF-κB to the nucleus. In addition, AP suppressed the TNF-α-induced degradation of IκB-α and attenuated the TNF-α-induced NF-κB binding. AP also effectively reduced TNF-α-induced mRNA expressions of monocyte chemoattractant protein (MCP)-1 and interleukin (IL)-8 in a dose-dependent manner. Taken together, AP prevents the vascular inflammatory process through the inhibition of intracellular ROS production and NF-κB activation as well as the reduction of adhesion molecule expression in TNF-α-induced HUVEC. These results suggested that AP might have a potential therapeutic effect by inhibiting the vascular inflammation process in vascular diseases such as atherosclerosis.
Effect of epitaxial strain on ferroelectric polarization in multiferroic BiFeO3 films
Dae Ho Kim,Ho Nyung Lee,Michael D. Biegalski,Hans M. Christen
Physics , 2007, DOI: 10.1063/1.2830799
Abstract: Multiferroic BiFeO3 epitaxial films with thickness ranging from 40 nm to 960 nm were grown by pulsed laser deposition on SrTiO3 (001) substrates with SrRuO3 bottom electrodes. X-ray characterization shows that the structure evolves from angularly-distorted tetragonal with c/a ~ 1.04 to more bulk-like distorted rhombohedral (c/a ~ 1.01) as the strain relaxes with increasing thickness. Despite this significant structural evolution, the ferroelectric polarization along the body diagonal of the distorted pseudo-cubic unit cells, as calculated from measurements along the normal direction, barely changes.
Ortho-to-Para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21
Jong-Ho Shinn,Ho-Gyu Lee,Dae-Sik Moon
Physics , 2012, DOI: 10.1088/0004-637X/759/1/34
Abstract: We present near-infrared (2.5-5.0 {\mu}m) spectral studies of shocked H2 gas in the two supernova remnants IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with Infrared Camera (IRC) aboard the AKARI satellite. At the energy range 7000 K <= E(v,J) <= 20000 K, the shocked H2 gas in IC 443 shows an ortho-to-para ratio (OPR) of 2.4+0.3-0.2, which is significantly lower than the equilibrium value 3, suggesting the existence of non-equilibrium OPR. The shocked gas in HB 21 also indicates a potential non-equilibrium OPR in the range of 1.8-2.0. The level populations are well described by the power-law thermal admixture model with a single OPR, where the temperature integration range is 1000-4000 K. We conclude that the obtained non-equilibrium OPR probably originates from the reformed H2 gas of dissociative J-shocks, considering several factors such as the shock combination requirement, the line ratios, and the possibility that H2 gas can form on grains with a non-equilibrium OPR. We also investigate C-shocks and partially-dissociative J-shocks for the origin of the non-equilibrium OPR. However, we find that they are incompatible with the observed ionic emission lines for which dissociative J-shocks are required to explain. The difference in the collision energy of H atoms on grain surfaces would make the observed difference between the OPRs of IC 443 and HB 21, if dissociative J-shocks are responsible for the H2 emission. Our study suggests that dissociative J-shocks can make shocked H2 gas with a non-equilibrium OPR.
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