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Search Results: 1 - 10 of 20490 matches for " Jongwon Kim "
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Effect of Laryngopharyngeal Anatomy on Expiratory Airflow and Submicrometer Particle Deposition in Human Extrathoracic Airways  [PDF]
Xiuhua Si, Jinxiang Xi, Jongwon Kim
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.34036
Abstract: The objective of this study is to systematically assess the influences of the larynopharyneal anatomical details on airflow and particle behaviors during exhalation by means of image-based modeling. A physiologically realistic nose-throat airway was developed with medical images. Individual airway anatomy such as uvula, pharynx, and larynx were then isolated for examination by progressively simplifying this image-based model geometry. Low Reynolds number (LRN) k-w model and Langrangian tracking model were used to simulate the dynamics of airflow and particle transport for a wide range of exhalation conditions (4-45 L/min) and particle sizes (1 nm-1 μm). Results showed that pharyngeal anatomical details exerted a significant impact on breathing resistance and particle profiles. Abrupt pressure drop resulting from the uvula-related airway obstruction was observed. Even though the total deposition rate in the nasal airway is largely unaffected by the upstream effect, the local deposition patterns vary notably. Results of this study also indicate that the pressure drop appears to be an appropriate parameter to characterize the geometric variations for diffusive depositions. Inclusion of pressure drop (D0.5Q-0.62dp0.07) gives an improved correlation than using the conventional diffusion factor (D0.5Q0.28).
Epoxidation of Diosgenin, 25(R)-1,4,6-Spirostatrien-3-one and 25(R)-4,6-Spirostadien-3β-ol
Eunsook Ma,Jongwon Kim
Molecules , 2003, DOI: 10.3390/81200886
Abstract: Upon treatment of 25(R)-spirost-5-en-3β-ol (diosgenin), 25(R)-1,4,6-spirostatrien-3-one and 25(R)-4,6-spirostadien-3β-ol with 30% H2O2 and 5% NaOH in methanol, diosgenin did not react, 25(R)-1,4,6-spirostatrien-3-one was converted to 25(R)-1α,2α-epoxy-4,6-spirostadien-3-one and 25(R)-4,6-spirostadien-3β-ol was oxidized to give a small amount of 25(R)-4,6-spirostadien-3-one, while most of the original starting material remained unchanged. On the other hand, reactions of diosgenin, 25(R)-1,4,6-spirostatrien-3-one and 25(R)-4,6-spirostadien-3β-ol with m-chloroperoxybenzoic acid in chloroform yielded 25(R)-5α,6α-epoxyspirostan-3β-ol, 25(R)-6α,7α-epoxy-1,4-spirostadien-3-one and 25(R)-4β,5β-epoxy-6-spirosten-3β-ol, respectively.
Design of 3D Space Following Positioning System Based on ZigBee  [PDF]
Liang Zhang, Xinnian Li, Honghuan Zhu, Jongwon Kim
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.31004
Abstract:

The research on positioning system and spatial alignment is a big topic. In this paper, we proposed a design (that) studies two issues. One is the study of range positioning algorithm based on ZigBee communication system. The other one is spatial alignment platform which is controlled with two servos. Hardware and software control system was realized, which also consists of two parts, ZigBee network positioning system and automatic orientation platform.

An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation
Nitin Radhakrishnan,Jongwon Park,Chang-Soo Kim
Sensors , 2012, DOI: 10.3390/s120708955
Abstract: Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems.
Media-Oriented Service Composition with Service Overlay Networks: Challenges, Approaches and Future Trends (Invited Paper)
JongWon Kim,Sang Woo Han,Dong-Hoon Yi,Namgon Kim
Journal of Communications , 2010, DOI: 10.4304/jcm.5.5.374-389
Abstract: The massive and timely delivery of media is gradually integrating itself with the dynamic composition of media-oriented services so that new types of customized media services can be created according to the diverse de- mand of end users. The resulting effective and differentiated networking support will become one of the most important requirements of the network infrastructure in the future. In this survey paper, we first present the emerging trend on the interaction of media-oriented service composition and overlay-based networks by introducing related technical issues. Then, we describe the top-down and the bottom- up approaches that coordinate service mapping using the service overlay networks (SONs) and provisioning resources for them, respectively. Finally, we examine latest research on futuristic overlay networks for service realization.
The Effects of Market Properties on Portfolio Diversification in the Korean and Japanese Stock Markets
Cheoljun Eom,Jongwon Park,Woo-Sung Jung,Taisei Kaizoji,Yong H. Kim
Quantitative Finance , 2009,
Abstract: In this study, we have investigated empirically the effects of market properties on the degree of diversification of investment weights among stocks in a portfolio. The weights of stocks within a portfolio were determined on the basis of Markowitz's portfolio theory. We identified that there was a negative relationship between the influence of market properties and the degree of diversification of the weights among stocks in a portfolio. Furthermore, we noted that the random matrix theory method could control the properties of correlation matrix between stocks; this may be useful in improving portfolio management for practical application.
Quantitative Morphological and Biochemical Studies on Human Downy Hairs using 3-D Quantitative Phase Imaging
SangYun Lee,Kyoohyun Kim,Yuhyun Lee,Sungjin Park,Heejae Shin,Jongwon Yang,Kwanhong Ko,HyunJoo Park,YongKeun Park
Physics , 2015,
Abstract: This study presents the morphological and biochemical findings on human downy arm hairs using 3-D quantitative phase imaging techniques. 3-D refractive index tomograms and high-resolution 2-D synthetic aperture images of individual downy arm hairs were measured using a Mach-Zehnder laser interferometric microscopy equipped with a two-axis galvanometer mirror. From the measured quantitative images, the biochemical and morphological parameters of downy hairs were non-invasively quantified including the mean refractive index, volume, cylinder, and effective radius of individual hairs. In addition, the effects of hydrogen peroxide on individual downy hairs were investigated.
Serum Bilirubin Affects Graft Outcomes through UDP-Glucuronosyltransferase Sequence Variation in Kidney Transplantation
Jung Pyo Lee, Do Hyoung Kim, Seung Hee Yang, Jin Ho Hwang, Jung Nam An, Sang Il Min, Jongwon Ha, Yun Kyu Oh, Yon Su Kim, Chun Soo Lim
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093633
Abstract: Background Oxidative stress is a major mediator of adverse outcome after kidney transplantation. Bilirubin is produced by heme oxygenase-1 (HO-1), catalyzed by UDP-glucuronosyltransferase (UGT1A1), and has potential as an antioxidant. In this study, we investigated the effects of HO-1 and UGT1A1 sequence variations on kidney allograft outcomes. Methods Clinical data were collected from 429 Korean recipients who underwent kidney transplantation from 1990–2008. Genotyping for UGT1A1*28 and HO-1 (A?413T) was performed. Acute rejection and graft survival were monitored as end-points. Results Serum levels of total bilirubin were significantly increased after transplantation (0.41±0.19 mg/dL to 0.80±0.33 mg/dL, P<0.001). Post-transplant 1-year bilirubin level was higher in 6/7 or 7/7 carriers compared with 6/6 homozygotes in terms of the UGT1A1*28 polymorphism (6/6 vs. 6/7 vs. 7/7: 0.71±0.27 vs. 1.06±0.36 vs. 1.10±0.45 mg/dL, P<0.001). According to an additive model of genotype analysis, the 7-allele genotype had a protective effect on the development of acute rejection compared with the 6-allele (odds ratio 0.43, 95% CI 0.25–0.73, P for trend = 0.006). Multivariate Cox regression analysis revealed that individuals carrying the 7-allele had a decreased risk of graft loss, by a factor of 0.36 (95% CI 0.15–0.85, P = 0.019). The HO-1 (A?413T) polymorphism had no effect on serum bilirubin levels or graft outcomes. Conclusions The UGT1A1*28 polymorphism is associated with changes in serum bilirubin and with graft outcome after kidney transplantation.
Open Strings in PP-Wave Background from Defect Conformal Field Theory
Peter Lee,Jongwon Park
Physics , 2002, DOI: 10.1103/PhysRevD.67.026002
Abstract: We consider open strings ending on a D5-brane in the pp-wave background, which is realized in the Penrose limit of $AdS_5 \times S^5$ with an $AdS_4\times S^2$ brane. A complete list of gauge invariant operators in the defect conformal field theory is constructed which is dual to the open string states.
Genetic Predisposition of Donors Affects the Allograft Outcome in Kidney Transplantation; Polymorphisms of Stromal-Derived Factor-1 and CXC Receptor 4
Jung Pyo Lee,Jong Bin Bae,Seung Hee Yang,Ran-hui Cha,Eun Young Seong,Yang Jin Park,Jongwon Ha,Myoung Hee Park,Jin Ho Paik,Yon Su Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016710
Abstract: Genetic interaction between donor and recipient may dictate the impending responses after transplantation. In this study, we evaluated the role of the genetic predispositions of stromal-derived factor-1 (SDF1) [rs1801157 (G>A)] and CXC receptor 4 (CXCR4) [rs2228014 (C>T)] on renal allograft outcomes. A total of 335 pairs of recipients and donors were enrolled. Biopsy-proven acute rejection (BPAR) and long-term graft survival were traced. Despite similar allele frequencies between donors and recipients, minor allele of SDF1 rs1801157 (GA+AA) from donor, not from recipients, has a protective effect on the development of BPAR compared to wild type donor (GG) (P = 0.005). Adjustment for multiple covariates did not affect this result (odds ratio 0.39, 95% C.I 0.20–0.76, P = 0.006). CXCR4 rs2228014 polymorphisms from donor or recipient did not affect the incidence of acute rejection. SDF1 was differentially expressed in renal tubular epithelium with acute rejection according to genetic variations of donor rs1801157 showing higher expressions in the grafts from GG donors. Contrary to the development of BPAR, the presence of minor allele rs1801157 A, especially homozygocity, predisposed poor graft survival (P = 0.001). This association was significant after adjusting for several risk factors (hazard ratio 3.01; 95% C.I = 1.19–7.60; P = 0.020). The allelic variation of recipients, however, was not associated with graft loss. A donor-derived genetic polymorphism of SDF1 has influenced the graft outcome. Thus, the genetic predisposition of donor should be carefully considered in transplantation.
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