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Search Results: 1 - 10 of 3882 matches for " Jong Bae "
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On the existence of solutions of strongly damped nonlinear wave equations
Jong Yeoul Park,Jeong Ja Bae
International Journal of Mathematics and Mathematical Sciences , 2000, DOI: 10.1155/s0161171200000971
Abstract: We investigate the existence and uniqueness of solutions of thefollowing equation of hyperbolic type with a strong dissipation:utt(t,x)−(α
Effect of data normalization on fuzzy clustering of DNA microarray data
Seo Kim, Jae Lee, Jong Bae
BMC Bioinformatics , 2006, DOI: 10.1186/1471-2105-7-134
Abstract: In this study we applied the fuzzy partitional clustering method known as Fuzzy C-Means (FCM) to overcome the limitations of hard clustering. To identify the effect of data normalization, we used three normalization methods, the two common scale and location transformations and Lowess normalization methods, to normalize three microarray datasets and three simulated datasets. First we determined the optimal parameters for FCM clustering. We found that the optimal fuzzification parameter in the FCM analysis of a microarray dataset depended on the normalization method applied to the dataset during preprocessing. We additionally evaluated the effect of normalization of noisy datasets on the results obtained when hard clustering or FCM clustering was applied to those datasets. The effects of normalization were evaluated using both simulated datasets and microarray datasets. A comparative analysis showed that the clustering results depended on the normalization method used and the noisiness of the data. In particular, the selection of the fuzzification parameter value for the FCM method was sensitive to the normalization method used for datasets with large variations across samples.Lowess normalization is more robust for clustering of genes from general microarray data than the two common scale and location adjustment methods when samples have varying expression patterns or are noisy. In particular, the FCM method slightly outperformed the hard clustering methods when the expression patterns of genes overlapped and was advantageous in finding co-regulated genes. Thus, the FCM approach offers a convenient method for finding subsets of genes that are strongly associated to a given cluster.DNA microarray technology has the potential to create enormous quantities of data in short times. The vast amounts of information generated by microarray experiments have led to the need for methods for analyzing such data. Clustering has proved to be an important tool for this purpose. Th
GA-Based Image Restoration by Isophote Constraint Optimization
Hang Joon Kim,Jong Bae Kim
EURASIP Journal on Advances in Signal Processing , 2003, DOI: 10.1155/s1687617203212142
Abstract: We propose an efficient technique for image restoration based on a genetic algorithm (GA) with an isophote constraint. In our technique, the image restoration problem is modeled as an optimization problem which, in our case, is solved by a cost function with isophote constraint that is minimized using a GA. We consider that an image is decomposed into isophotes based on connected components of constant intensity. The technique creates an optimal connection of all pairs of isophotes disconnected by a caption in the frame. For connecting the disconnected isophotes, we estimate the value of the smoothness, given by the best chromosomes of the GA and project this value in the isophote direction. Experimental results show a great possibility for automatic restoration of a region in an advertisement scene.
Microwave distribution in stacked Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ intrinsic Josephson junctions in a transmission-line geometry
Myung-Ho Bae,Hu-Jong Lee
Physics , 2003, DOI: 10.1063/1.1610258
Abstract: The microwave distribution inside a rectangular stack (15 $\mu$m$\times$0.72 $\mu$m$\times$60 nm) of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ intrinsic Josephson junctions (IJJs) was studied. The stack was microfabricated into a transmission-line geometry, with a few hundred nm thick Au layers deposited on top and bottom of the stack. The microwave distribution was monitored by measuring the anomalous suppression of the tunneling critical current of the IJJs with varied microwave power at frequencies in the W band. This technique can provide valuable information on the microwave transmission modes inside the sandwiched stack of IJJs, which is utterly important for the high-frequency device applications using IJJs, such as fluxon-flow THz oscillators.
Vortex-flow electromagnetic emission in stacked intrinsic Josephson junctions
Myung-Ho Bae,Hu-Jong Lee
Physics , 2006, DOI: 10.1063/1.2191415
Abstract: We confirmed the existence of the collective transverse plasma modes excited by the motion of the Josephson vortex lattice in stacked intrinsic Josephson junctions of Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ by observing the multiple subbranches in the Josephson-vortex-flow current-voltage characteristics. We also observed the symptom of the microwave emission from the resonance between the Josephson vortex lattice and the collective transverse plasma modes, which provides the possibility of developing Josephson-vortex-flow electromagnetic oscillators.
Collective resonance modes of Josephson vortices in sandwiched stack of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ intrinsic Josephson junctions
Myung-Ho Bae,Hu-Jong Lee
Physics , 2003, DOI: 10.1103/PhysRevB.70.052506
Abstract: We observed splitting of the low-bias vortex-flow branch in a dense-Josephson-vortex state into multiple sub-branches in current-voltage characteristics of intrinsic Josephson junctions (IJJs) of Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ single crystals in the long-junction limit. Each sub-branch corresponds to a plasma mode in serially coupled Josephson junctions. Splitting into low-bias linear sub-branches with a spread in the slopes and the inter-sub-branch mode-switching character are in good quantitative agreement with the prediction of the weak but finite inter-junction capacitive-coupling model incorporated with the inductive coupling. This suggests the importance of the role of the capacitive coupling in accurately describing the vortex dynamics in serially stacked IJJs.
A Census of Gas Outflows in Type 2 Active Galactic Nuclei
Hyun-Jin Bae,Jong-Hak Woo
Physics , 2014, DOI: 10.1088/0004-637X/795/1/30
Abstract: We perform a census of ionized gas outflows using a sample of ~23,000 type 2 active galactic nuclei (AGNs) out to z~0.1. By measuring the velocity offset of narrow emission lines, i.e., [O III] {\lambda}5007 and H{\alpha}, with respect to the systemic velocity measured from the stellar absorption lines, we find that 47% of AGNs display an [O III] line-of-sight velocity offset $\geq$ 20 km/s. The fraction of the [O III] velocity offset in type 2 AGNs is comparable to that in type 1 AGNs after considering the projection effect. AGNs with a large [O III] velocity offset preferentially have a high Eddington ratio, implying that the detected velocity offsets are related to black hole activity. The distribution of the host galaxy inclination is clearly different between the AGNs with blueshifted [O III] and the AGNs with redshifted [O III], supporting the combined model of the biconical outflow and dust obscuration. In addition, for ~3% of AGNs, [O III] and H{\alpha} show comparable large velocity offsets, indicating a more complex gas kinematics than decelerating outflows in a stratified narrow-line region.
A Skin Fixation Method for Decreasing the Influence of Wound Contraction on Wound Healing in a Rat Model
Seong Hwan Bae,Yong Chan Bae,Su Bong Nam,Soo Jong Choi
Archives of Plastic Surgery , 2012, DOI: http://dx.doi.org/10.5999/aps.2012.39.5.457
Abstract: Background The elasticity of the back skin of the rat reduced the tension around woundsduring the wound healing process in that region, and thus activates wound contraction. Theauthors proposed two skin fixation methods using readily available materials to decrease theinfluence of wound contraction on wound healing and designed an experiment to determinetheir effects.Methods The authors made 36 skin wounds on the backs of 18 rats, and they divided theminto three groups. Each group was treated with three different kinds of dressing materials,each with different skin fixing characteristics. Group A was a control group. Group B andgroup C were dressed by the first and the second skin fixation method. We measured the areasof the wounds post-surgically and calculated the wound area reduction rates.Results The two skin fixation methods both reduced the effect of wound contractioncompared to the control group. Each of the two methods had different outcomes in reducingwound contraction.Conclusions The experiment demonstrated significant differences among the wound areasand the wound area reduction rates of the three groups as a result of differences in thedegree of wound contraction. To obtain accurate results from wound healing experiments,appropriate skin fixation methods must be adopted.
An In-situ XPS study of non-evaporable ZrVFe getter material
Jang-Hee Yoon,Won Baek Kim,Jong Sung Bae,Jong Pil Kim
Journal of Analytical Science & Technology , 2010,
Abstract: To investigate the temperature dependence of a synthesized Zr57V36Fe7 non evaporable vacuum getter material, the in-situ temperature x-ray photoelectron spectroscopy (in-situ XPS) were performed in a UHV chamber equipped with a programmable ceramic sample heating system. The surface and bulk composition of Zr, V, and Ti was determined in the as-received state and after in-situ heating from 50℃ to 600℃ at 50℃per step. The peak fitting results for O 1s, C 1s, Zr 3d, V 2p, and Fe 2p high resolution spectra were acquired and the chemical state of the elements were then characterized as a function of heating temperature. In-situ XPS investigations showed that oxide reduction proceeds via the formation of sub-oxides with the simultaneous formation of carbides in the region near the surface. The activation temperature for completion of the Zr57V36Fe7 alloy, which approximates the XPS peaks changed from oxide to metallic state(20 % of the oxide peak), was determined around 480℃. The findings suggest that the in-situ temperature XPS technique is a useful analytical tool for evaluating activation characteristics of NEG materials.
Depth profile analysis of nanometric multilayer coatings by radio-frequency glow discharge optical emission spectroscopy
Jang-Hee Yoon,Jong-Pil Kim,Kyung Joong Kim,Jong-Seong Bae
Journal of Analytical Science & Technology , 2010,
Abstract: Radiofrequency glow discharge optical emission spectrometry(RF-GD-OES) was used to quantitatively analyze the depth of nanometric Cr/Ni multilayers on a silicon substrate. The technique permitted the rapid and accurate depth profiling of multilayers, down to the nanometer range. The analytical parameters were optimized for the RF-GD-OES depth quantitative analysis of Cr/Ni multilayers on a Si substrate. To validate the RF-GD-OES results, a TEM image was obtained in addition to performing the AES and SIMS depth profiling. confirm the validity of the GD-OES data, TEM imagewas obtained and both AES depth profiling, and SIMS depth profiling were preformed. The findings indicate that RF-GD-OES is a promising analytical tool for the accurate and rapid depth profiling of nanometric metal multilayers on semiconducting substrates.
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