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Search Results: 1 - 10 of 20710 matches for " Gyeong-Ok Kim "
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Synthesis and Control of the Shell Thickness of Polyaniline and Polypyrrole Half Hollow Spheres Using the Polystyrene Cores
Su-Ryeon Yun,Gyeong-Ok Kim,Chan Woo Lee,Nam-Ju Jo,Yongku Kang,Kwang-Sun Ryu
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/894539
Abstract: Polyaniline (Pani) and polypyrrole (Ppy) half hollow spheres with different shell thicknesses were successfully synthesized by three steps process using polystyrene (PS) as the core. The PS core was synthesized by emulsion polymerization. Aniline and pyrrole monomers were polymerized on the surface of the PS core. The shells of Pani and Ppy were fabricated by adding different amounts of aniline and pyrrole monomers. PS cores were dissolved and removed from the core shell structure by solvent extraction. The thicknesses of the Pani and Ppy half hollow spheres were observed by FE-SEM and FE-TEM. The chemical structures of the Pani and Ppy half hollow spheres were characterized by FT-IR spectroscopy and UV-Vis spectroscopy. The shell thicknesses of the Pani half hollow spheres were 30.2, 38.0, 42.2, 48.2, and 52.4 nm, while the shell thicknesses of the Ppy half hollow spheres were 16.0, 22.0, 27.0, and 34.0 nm. The shell thicknesses of Pani and Ppy half hollow spheres linearly increased as the amount of the monomer increased. Therefore, the shell thickness of the Pani and Ppy half hollow spheres can be controlled in these ranges.
Fruit Characteristics and Mineral Nutrient Concentrations Depending on Different Sizes of “Fuyu” Persimmon Fruits  [PDF]
Seong-Tae Choi, Gwang-Hwan Ahn, Eun-Gyeong Kim, Ji-Young Son, Yeo-Ok Park, Wan-Kyu Joung
Agricultural Sciences (AS) , 2019, DOI: 10.4236/as.2019.108076
Abstract: This study investigated the relationships between fruit size and other fruit quality components in “Fuyu” persimmon. The flower buds were thinned to leave one or two buds per bearing shoot in mid-May. All fruits were harvested on November 12 and they were divided into six size classes by fresh weight. The length/diameter (L/D) ratio and flesh firmness significantly decreased as fruit size increased. Large fruits had a redder skin color with more seeds than small ones. There was a strong negative relationship between fruit size and the L/D ratio (R2 = 0.741, p ≤ 0.01) and firmness (R2 = 0.604, p ≤ 0.01). Skin color and number of seeds per fruit were positively related to fruit size, especially skin color where the relationship was highly positive (R2 = 0.771, p ≤ 0.01). There was a weak, but non-significant positive relation between fruit size and soluble solids. P, K, and Ca concentrations significantly decreased with increasing fruit size. Highly negative relationships were found between fruit size and fruit P (R2 = 0.393, p ≤ 0.01), K (R2 = 0.446, p ≤ 0.01), and Ca (R2 = 0.417, p ≤ 0.01) concentrations. Fruit N and Mg concentrations were not affected by fruit size. It was concluded that fruit size is related to shape, coloration, flesh firmness, and number of seeds per fruit, affecting concentrations of some mineral nutrients in fruits.
The Effect of Smartwork Environment on Organizational Commitment and Innovative Behavior in the Global Financial Service Industry  [PDF]
Myong Ok Kim, Sooyeon Shin
Journal of Service Science and Management (JSSM) , 2015, DOI: 10.4236/jssm.2015.81014
Abstract: This study analyzed how smartwork environment perceived by employees in global financial service industry (GFSI) influences their organizational commitment and innovative behavior. Data were collected through a questionnaire survey from 147 respondents randomly selected from seven global financial service firms in Seoul, Korea, where all three types of smartwork setting (working at home, mobile office, and smartwork center) are utilized. We found that no specific characteristic of smartwork environment (presenteeism, IT complexity, security risks, task interdependence) was significantly related to organizational commitment. For innovative behavior, only IT complexity and security risks of smartwork environment appeared to be significantly related. Contrary to our expectations, it was found that the negative emotion and stress of employees as to the complexity of IC technology and IT security risks can actually inspire their innovative behavior.
Quantile regression with varying coefficients
Mi-Ok Kim
Mathematics , 2007, DOI: 10.1214/009053606000000966
Abstract: Quantile regression provides a framework for modeling statistical quantities of interest other than the conditional mean. The regression methodology is well developed for linear models, but less so for nonparametric models. We consider conditional quantiles with varying coefficients and propose a methodology for their estimation and assessment using polynomial splines. The proposed estimators are easy to compute via standard quantile regression algorithms and a stepwise knot selection algorithm. The proposed Rao-score-type test that assesses the model against a linear model is also easy to implement. We provide asymptotic results on the convergence of the estimators and the null distribution of the test statistic. Empirical results are also provided, including an application of the methodology to forced expiratory volume (FEV) data.
Dynamic choosability of triangle-free graphs and sparse random graphs
Jaehoon Kim,Seongmin Ok
Mathematics , 2015,
Abstract: The \textit{$r$-dynamic choosability} of a graph $G$, written ${\rm ch}_r(G)$, is the least $k$ such that whenever each vertex is assigned a list of at least $k$ colors a proper coloring can be chosen from the lists so that every vertex $v$ has at least $\min\{d_G(v),r\}$ neighbors of distinct colors. Let ${\rm ch}(G)$ denote the choice number of $G$. In this paper, we prove ${\rm ch}_r(G)\leq (1+o(1)){\rm ch}(G)$ when $\frac{\Delta(G)}{\delta(G)}$ is bounded. We also show that there exists a constant $C$ such that for the random graph $G=G(n,p)$ with $\frac{2}{n}
Isolation and Characterization of Volatile Organic Compounds-Degrading Bacillus Strains from Loess  [PDF]
Soo Yeon Lee, Hye Yun Oh, Ok Bin Kim
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.44A007
Abstract:

Volatile organic compounds (VOCs) are harmful to human health and the environment. Recently, loess (Hwangtoh) was used as an eco-friendly interior paint formulation in Korea. It is used even more commonly as a filter carrier to remove VOCs. In this study, we isolated Bacillus strains from a loess filter. The strains that were tolerant to VOCs were labeled according to the series VOC01 to VOC35. Four strains—VOC03, VOC11, VOC18, and VOC30—were investigated for their ability to degrade cyclohexane and toluene. Strain VOC18 best degraded both VOCs, whereas VOC03 demonstrated no ability to degrade VOCs. In keeping with this, VOC18 grew best on cyclohexane or toluene as the sole carbon source. The strains were identified by their physiochemical and phylogenetic characteristics. Strain VOC18 was determined as a strain of Bacillus cereus; VOC11 and VOC30 were determined as differentiated strains of B. thuringiensis. Strain VOC03, which demonstrated high tolerance but no ability to degrade VOCs, was identified as a strain of B. megaterium.

Buffon’s Needle Algorithm to Estimate π  [PDF]
Chi-Ok Hwang, Yeongwon Kim, Cheolgi Im, Sunggeun Lee
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.83022
Abstract: Buffon’s needle experiment was originally devised to get the value of π. With the advent of computers, Buffon’s needle algorithm has been used pedagogically as an example of Monte Carlo methods in introduction classes, and there are many Buffon’s needle algorithm implementations available on the internet. However, for the calculation of π, the exact value of π is used in the programs for Buffon’s needle angle sampling, and hence the example is not demonstrated correctly. This brief note presents a random angle sampling algorithm for the Buffon’s needle. We then compare the Buffon’s needle and Hit-and-Miss integration algorithms using Monte Carlo laboriousness comparison, and find that the Hit-and-Miss algorithm is superior.
Enhanced stability of nano-emulsified paclitaxel  [PDF]
Ju Young Lee, Da Yeon Kim, Gyeong Hae Kim, Kkot Nim Kang, Byoung Hyun Min, Bong Lee, Jae Ho Kim, Moon Suk Kim
Journal of Biomedical Science and Engineering (JBiSE) , 2011, DOI: 10.4236/jbise.2011.45044
Abstract: The main goal of this work was to develop an optimal self-microemulsifying paclitaxel prepared with PLGA and solubilizer such as tetraglycol, Cremophor ELP, and Labrasol. The prepared PTx-loaded SMES showed the size of the range of 80–130 nm by dy-namic light scattering and a spherical shape by atomic force microscopy. In experiment of storage stability in deionized water (DW) or blood condition, PTx-loaded SMES showed good stability in DW and comparable stability in blood condition at 37oC for 7 days. In addition, PTx-loaded SMES showed a sig-nificant inhibitory effect on B16F10 melanoma proli-feration. In conclusion, we confirmed that the for-mulations tried in this study could be used as admin-istration form for animal trials of PTx.
Patterns of Citing Korean DOI Journals According to CrossRef's Cited-by Linking and a Local Journal Citation Database
Tae-Sul Seo,Eun-Gyeong Jung,Hwanmin Kim
Journal of Information Science Theory and Practice , 2013, DOI: 10.1633/jistap.2013.1.2.4
Abstract: Citing literature is a very important activity for scholars in writing articles. Many publishers and libraries build citation databases and provide citation reports on scholarly journals. Cited-by linking is a service representing what an article cites and how many times it cites a specific article within a journal database. Recently, information services based on DOIs (Digital Object Identifiers) have been increasing in number. CrossRef, a non-profit organization for the DOI registration agency, maintains the DOI system and provides the cited-by linking service. Recently, the number of Korean journals adopting DOI is also rapidly increasing. The Korea Institute of Science and Technology Information (KISTI) supports Korean learned societies in DOI related activities in collaboration with CrossRef. This study analyzes cited patterns of Korean DOI journal articles using CrossRef's cited-by linking data and a Korean journal citation database. This analysis has been performed in terms of publication country and the language of journals citing Korean journal articles. The results show that DOI, SCI(E) (Science Citation Index (Expanded)), and English journals are more likely to be cited internationally.
Characteristics of neutrons and proton beams arising from two different Beam Nozzles
Yeon-Gyeong Choi,Yu-Seok Kim
Physics , 2015,
Abstract: Tandem or Van de Graaff accelerator with an energy of 3-MeV is typically used for PIXE analysis. In this study, the beam line design used in PIXE analysis was used to increase the production of isotopes instead of the typical low-energy accelerator from a 13-MeV cyclotron. For PIXE analysis, the proton beam should be focused at the target through the use of a nozzle after degrading the proton beam energy from 13-MeV to 3-MeV using an energy degrader. Previous studies have been conducted to determine the most appropriate material and thickness of the energy degrader. Based on the energy distribution of the degraded proton beam and the neutron occurrence rate at the degrader an aluminum nozzle of X thickness was determined to be the most appropriate nozzle construction. Neutrons are created by the collision of 3-MeV protons into the nozzle after passage through energy degrader. In addition, a sufficient intensity of proton beam is required for non-destructive analysis of PIXE. Therefore, in order to optimize nozzle design, it is necessary to consider the number of neutrons which arise from the collision of protons inside the nozzle, as well as the track direction of the generated secondary neutrons, with the primary aim of ensuring a sufficient number of protons passing through the nozzle as a direct beam. A number of laboratories are currently conducting research related to the design of nozzles used in accelerator fields, mostly relating to medical fields. In this paper, a comparative analysis was carried out for two typical nozzle shapes in order to minimize losses of protons and generation of secondary neutrons. The neutron occurrence rate and the number of protons after passing through the nozzle were analyzed using a Particle and Heavy Ion Transport code System (PHITS) program, in order to identify the nozzle which generated the strongest proton beam.
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