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Search Results: 1 - 10 of 652 matches for " YEON "
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3D volume extraction of cerebrovascular structure on brain magnetic resonance angiography data sets  [PDF]
Do-Yeon Kim
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.510070
Abstract: The use of computers in facilitating their processing and analysis has become necessary with the increaseing size and number of medical images. In particular, computer algorithms for the delineation of anatomical structures and other regions of interest, which are called image segmentation, play a vital role in numerous biomedical imaging applications such as the quantification of tissue volumes, diagnosis, localization of pathology, study of anatomical structure, treatment planning, and computer-integrated surgery. In this paper, a 3D volume extraction algorithm was proposed for segmentation of cerebrovascular structure on brain MRA data sets. By using a priori knowledge of cerebrovascular structure, multiple seed voxels were automatically identified on the initially thresholded image. In the consideration of the preserved voxel connectivity—which is defined as 6-connectivity with joint faces, 18-connectivity with joint edges, and 26-connectivity with joint corners— the seed voxels were grown within the cerebrovascular structure area throughout 3D volume extraction process. This algorithm provided better segmentation results than other segmentation methods such as manual, and histogram thresholding approach. This 3D volume extraction algorithm is also applicable to segment the tree-like organ structures such as renal artery, coronary artery, and airway tree from the medical imaging modalities.
Hepatic vessel segmentation on contrast enhanced CT image sequence for liver transplantation planning  [PDF]
Do-Yeon Kim
Journal of Biomedical Science and Engineering (JBiSE) , 2013, DOI: 10.4236/jbise.2013.64063
Abstract:

The structure and morphology of the hepatic vessels and their relationship between tumors and liver segments are major interests to surgeons for liver surgical planning. In case of living donor liver transplantation (LDLT), the most important step in determining donor suitability is an accurate assessment of the liver volume available for transplantation. In addition, the mutual principles of the procedures include dissection in the appropriate anatomic plane without portal occlusion, minimization of blood loss, and avoidance of injury to the remaining liver. It is essential first step to identify and evaluate the major hepatic vascular structure for liver surgical planning. In this paper, the threshold was determined to segment the liver region automatically based on the distribution ratio of intensity value; and the hepatic vessels were extracted with mathematical morphology transformation, which called hit operation, that is slightly modified version of hit-and-miss operation on contrast enhanced CT image sequence. We identified the vein using the preserved voxel connectivity between two consecutive transverse image sequences, followed by resection into right lobe including right hepatic vein, middle hepatic vein branches andleft lobe including left hepatic vein. An automated hepatic vessel segmentation scheme is recommended for liver surgical planning such as tumor resection and transplantation. These vessel extraction method combined with liver region segmentation technique could be applicable to extract tree-like organ structures such as carotid, renal, coronary artery, and airway path from various medical imaging modalities.

Computer Simulation Study of Biopolymer Betanova  [PDF]
Seung-Yeon Kim
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.312002
Abstract:

Betanova is a monomeric, three-stranded antiparallel beta-sheet protein with twenty residues. The pathways between the folded native structure and unfolded conformations of betanova are studied using UNRES force field and the most popular computer simulation method, Metropolis Monte Carlo algorithm. At a fixed temperature, 100 Monte Carlo simulations are performed, starting from the folded native structure, and the pathways are obtained at two different temperatures.

Folding and Unfolding Simulations of a Three-Stranded Beta-Sheet Protein  [PDF]
Seung-Yeon Kim
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.41003
Abstract:

Understanding the folding processes of a protein into its three-dimensional native structure only with its amino-acid sequence information is a long-standing challenge in modern science. Two- hundred independent folding simulations (starting from non-native conformations) and two- hundred independent unfolding simulations (starting from the folded native structure) are performed using the united-residue force field and Metropolis Monte Carlo algorithm for betanova (three-stranded antiparallel beta-sheet protein). From these extensive computer simulations, two representative folding pathways and two representative unfolding pathways are obtained in the reaction coordinates such as the fraction of native contacts, the radius of gyration, and the root- mean-square deviation. The folding pathways and the unfolding pathways are similar each other. The largest deviation between the folding pathways and the unfolding pathways results from the root-mean-square deviation near the folded native structure. In general, unfolding computer simulations could capture the essentials of folding simulations.

Synthesizing Nanoparticles Using Reactions Occurring in Aerosol Phases  [PDF]
Ho Yeon Yoo, Stanley Bruckenstein
Advances in Nanoparticles (ANP) , 2013, DOI: 10.4236/anp.2013.24042
Abstract:

Our ultimate objective is to form nanoparticles by merging oppositely charged nanodroplets containing different constituents of the nanoparticle and construct a desktop apparatus to do this. These nanodroplets will be in oppositely charged aerosols originating from oppositely charged solutions containing the different component of the nanoparticle. In this paper, as the first stage in establishing the feasibility of this concept, we demonstrate that droplets formed from uncharged solutions will merge and the product of such reactions is the same as when their bulk solutions are mixed. We demonstrate that this is the case for three classes of reactions: the chemiluminescent reaction between Luminol and Potassium Ferricyanide, the pH sensitive fluorescence of Umbelliferone and the precipitation of Silver Chromate by reaction of Silver Nitrate with Potassium Chromate. We present arguments that our future goal using oppositely charged droplets is more efficient synthetically and will produce a narrow distribution of nanoparticle sizes.

Overexpression of OsMAPK2 Enhances Low Phosphate Tolerance in Rice and Arabidopsis thaliana  [PDF]
Yeon Jae Hur, Doh Hoon Kim
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.54059
Abstract:

The mitogen-activated protein kinase (MAPK) cascade is the most important mechanism in environmental responses and developmental processes in plants. The OsMAPK2 gene has been found to function in plant tolerance to diverse biotic/abiotic stresses. This paper presents evidence that OsMAPK2 (Oryza sativa MAP kinase gene 2) is responsive to Pi deficiency and involved in Pi homeostasis. We found that full-length expression of OsMAPK2 was up-regulated in both rice plants and cell culture in the absence of inorganic phosphate (Pi). The transgenic rice and Arabidopsis plants overexpressing OsMAPK2 showed affected root development and increased plant Pi content compared with wild-type plants. Overexpression of OsMAPK2 controlled the expression of several Pi starvation-responsive genes. Our results indicated that OsMAPK2 enables tolerance phosphate deficiency and is involved in Pi homeostasis.

Probing for Dynamics of Dark-Energy in Mass Varying Neutrinos: Cosmic Microwave Background Radiation and Large Scale Structure
Keum, Yong-Yeon
High Energy Physics - Phenomenology , 2007, DOI: 10.1142/S0217732307025388
Abstract: We present cosmological perturbation theory in neutrino probe interacting dark-energy models, and calculate cosmic microwave background anisotropies and matter power spectrum. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for the cosmic acceleration today. We consider several types of scalar field potentials and put constraints on the coupling parameter between neutrinos and dark energy. Assuming the flatness of the universe, the constraint we can derive from the current observation is $\sum m_{\nu} < 0.87 eV$ at the 95 % confidence level for the sum over three species of neutrinos.
An evaluation of empirical regression models for predicting temporal variations in soil respiration in a cool-temperate deciduous broad-leaved forest
Na-Yeon Lee
Journal of Ecology and Field Biology , 2010,
Abstract: Soil respiration (RS) is a critical component of the annual carbon balance of forests, but few studies thus far haveattempted to evaluate empirical regression models in RS. The principal objectives of this study were to evaluate therelationship between RS rates and soil temperature (ST) and soil water content (SWC) in soil from a cool-temperatedeciduous broad-leaved forest, and to evaluate empirical regression models for the prediction of RS using ST and SWC.We have been measuring RS, using an open-flow gas-exchange system with an infrared gas analyzer during the snowfreeseason from 1999 to 2001 at the Takayama Forest, Japan. To evaluate the empirical regression models used for theprediction of RS, we compared a simple exponential regression (flux = aebt: Eq. [1]) and two polynomial multiple-regressionmodels (flux = aebt × (θν – c) × (d – θν)f: Eq. [2] and flux = aebt × (1 – (1 – (θν/c))2): Eq. [3]) that included two variables (ST:t and SWC: θν) and that utilized hourly data for RS. In general, daily mean RS rates were positively well-correlated withST, but no significant correlations were observed with any significant frequency between the ST and RS rates on periodsof a day based on the hourly RS data. Eq. (2) has many more site-specific parameters than Eq. (3) and resulted in somesignificant underestimation. The empirical regression, Eq. (3) was best explained by temporal variations, as it provideda more unbiased fit to the data compared to Eq. (2). The Eq. (3) (ST × SWC function) also increased the predictive abilityas compared to Eq. (1) (only ST exponential function), increasing the R2 from 0.71 to 0.78.
Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps
Moo-Yeon Lee
Advances in Mechanical Engineering , 2012, DOI: 10.1155/2012/863731
Abstract:
A Checklist of the Families Lonchaeidae, Pallopteridae, Platystomatidae, and Ulidiidae (Insecta: Diptera: Tephritoidea) in Korea with Notes on 12 Species New to Korea
Ho-Yeon Han
Animal Systematics, Evolution and Diversity , 2013, DOI: http://dx.doi.org/10.5635/ased.2013.29.1.56
Abstract: A preliminary list of the following four tephritoid families is provided including 30 Korean species, of which 12 are new to Korea: two Lonchaeidae, three Pallopteridae (two new to Korea), 17 Platystomatidae (two new to Korea), and eight Ulidiidae (all new to Korea). This list is mainly based on the insect collection at the Yonsei University Wonju Campus and on previous publications concerning these taxa. Although a full taxonomic revision for each family is required in the long term, this preliminary list will provide a useful starting point to further investigation of these families. For the other three tephritoid families known in Korea but not treated in the present study, 89 species of Tephritidae, 14 species of Pyrgotidae, and one species of the rare family Ctenostylidae have been reported previously. A total of 134 species in seven families are officially recognized for the Korean fauna of the superfamily Tephritoidea.
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