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Search Results: 1 - 10 of 25878 matches for " Dae-Woong Lee "
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On the same $N$-type of the suspension of the infinite quaternionic projective space
Dae-Woong Lee
Mathematics , 2010,
Abstract: Let $[\rho_{i_k},[\rho_{i_{k-1}},...,[\rho_{i_{1}}, \rho_{i_2}] ...]]$ be an iterated commutator of self-maps $\rho_{i_j} : \Sigma {\Bbb H}P^\infty \to \Sigma {\Bbb H}P^\infty, j = 1,2, ..., k$ on the suspension of the infinite quaternionic projective space. In this paper, it is shown that the image of the homomorphism induced by the adjoint of this commutator is both primitive and decomposable. The main result in this paper asserts that the set of all homotopy types of spaces having the same $n$-type as the suspension of the infinite quaternionic projective space is the one element set consisting of a single homotopy type. Moreover, it is also shown that the group $\text{Aut}(\pi_{\leq n} (\Sigma {\Bbb H}P^\infty)/\text{torsion})$ of automorphisms is finite for $n \leq 9$, and infinite for $n \geq 13$, and that $\text{Aut}(\pi_{*} (\Sigma {\Bbb H}P^\infty)/\text{torsion})$ becomes non-abelian.
On the digital homology groups of digital images
Dae-Woong Lee
Computer Science , 2011,
Abstract: In this article we study the digital homology groups of digital images which are based on the singular homology groups of topological spaces in algebraic topology. Specifically, we define a digitally standard $n$-simplex, a digitally singular $n$-simplex, and the digital homology groups of digital images with $k$-adjacency relations. We then construct a covariant functor from a category of digital images and digitally continuous functions to the one of abelian groups and group homomorphisms, and investigate some fundamental and interesting properties of digital homology groups of digital images, such as the digital version of the dimension axiom which is one of the Eilenberg-Steenrod axioms.
Comparison of Risk Assessment for a Nuclear Power Plant Construction Project Based on Analytic Hierarchy Process and Fuzzy Analytic Hierarchy Process  [PDF]
Dae-Woong Shin, Yoonseok Shin, Gwang-Hee Kim
Journal of Building Construction and Planning Research (JBCPR) , 2016, DOI: 10.4236/jbcpr.2016.43010
Abstract: Recently, plant construction throughout the world, including nuclear power plant construction, has grown significantly. The scale of Korea’s nuclear power plant construction in particular, has increased gradually since it won a contract for a nuclear power plant construction project in the United Arab Emirates in 2009. However, time and monetary resources have been lost in some nuclear power plant construction sites due to lack of risk management ability. The need to prevent losses at nuclear power plant construction sites has become more urgent because it demands professional skills and large-scale resources. Therefore, in this study, the Analytic Hierarchy Process (AHP) and Fuzzy Analytic Hierarchy Process (FAHP) were applied in order to make comparisons between decision-making methods, to assess the potential risks at nuclear power plant construction sites. To suggest the appropriate choice between two decision-making methods, a survey was carried out. From the results, the importance and the priority of 24 risk factors, classified by process, cost, safety, and quality, were analyzed. The FAHP was identified as a suitable method for risk assessment of nuclear power plant construction, compared with risk assessment using the AHP. These risk factors will be able to serve as baseline data for risk management in nuclear power plant construction projects.
Age-related changes of ocular parameters in Korean subjects
Dae Woong Lee, Joon Mo Kim, Chul Young Choi, et al
Clinical Ophthalmology , 2010, DOI: http://dx.doi.org/10.2147/OPTH.S11661
Abstract: ge-related changes of ocular parameters in Korean subjects Original Research (3054) Total Article Views Authors: Dae Woong Lee, Joon Mo Kim, Chul Young Choi, et al Published Date July 2010 Volume 2010:4 Pages 725 - 730 DOI: http://dx.doi.org/10.2147/OPTH.S11661 Dae Woong Lee1, Joon Mo Kim1, Chul Young Choi1, Donghun Shin2, Ki Ho Park3, Jung Gon Cho4 1Department of Ophthalmology, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea; 2School of Medicine, University of Queensland, Brisbane, Queensland, Australia; 3Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea; 4Yebon Eye Clinic, Seoul, Korea Aims: To evaluate the age-related variations of ocular parameters in Korean subjects. Methods: We recruited 314 normal subjects who visited the department of -Ophthalmology between January 2007 and October 2007. Refraction, axial length, corneal curvature, white-to-white distance, anterior chamber depth, corneal endothelial cell density, and retinal nerve fiber layer (RNFL) thickness were measured using auto-refractive keratometer, intraocular lens master, noncontact specular microscope, and optical coherence tomography. Result: In correlation analysis, from 19 to 82 years, hyperopic shift showed a strong positive statistical correlation with age (r = 0.553, P < 0.001). Corneal curvatures increased (r = 0.221, P < 0.001), while axial length (r = -0.506, P < 0.001), anterior chamber depth (r = -0.491, P < 0.001) and white-to-white distance (r = -0.205, P < 0.001) decreased with age. Also, -corneal endothelial cell density was lower in older patients than in younger patients (r = -0.409, P < 0.001). Compared to younger patients, RNFL thickness was lower in the older patients as well, in all quadrants (superior, r = -0.283, P < 0.001; inferior, r = -0.230, P < 0.001; nasal, r = 0.025, P = 0.676; and temporal, r = -0.393, P < 0.001). According to multiple regression analysis, out of the six parameters measured, only hyperopic shift, anterior chamber depth and corneal endothelial cell density (P < 0.05) had statistically significant -correlation with age. Conclusion: Some of the ocular parameters changed with aging. Hyperopic shift, shallowing anterior chamber depth, and reduction of corneal endothelial cell density were only definitely related to age.
Technical issues and new devices of ESD of early gastric cancer
Wan Sik Lee,Jin Woong Cho,Young Dae Kim,Kyu Jong Kim
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i31.3585
Abstract: Endoscopic submucosal dissection (ESD) is a highly refined technique compared to conventional endoscopic mucosal resection. It enables complete resection of early gastric cancer (EGC) which has no possibility of lymph node metastasis. Indication for ESD of EGC generally entails early gastric cancer confined to the mucosa with well differentiated histology, though there are clinically suitable expanded criteria. As ESD requires specific skill and expertise, endoscopists need to be familiarized with basic methods and the use of special devices. The essence of the technique is to dissect the submucosal layer with direct vision and maintain the cutting plane above the underlying proper muscle layer. Although there are some differences in the detailed technical aspect, the cardinal method of ESD is now well established and standardized. Furthermore, research and development of new ESD devices that render more efficient, safe ESD are still in progress to improve the overall result of ESD on early gastric cancer.
Age-related changes of ocular parameters in Korean subjects
Dae Woong Lee,Joon Mo Kim,Chul Young Choi,et al
Clinical Ophthalmology , 2010,
Abstract: Dae Woong Lee1, Joon Mo Kim1, Chul Young Choi1, Donghun Shin2, Ki Ho Park3, Jung Gon Cho41Department of Ophthalmology, Sungkyunkwan University School of Medicine, Kangbuk Samsung Hospital, Seoul, Korea; 2School of Medicine, University of Queensland, Brisbane, Queensland, Australia; 3Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea; 4Yebon Eye Clinic, Seoul, KoreaAims: To evaluate the age-related variations of ocular parameters in Korean subjects.Methods: We recruited 314 normal subjects who visited the department of -Ophthalmology between January 2007 and October 2007. Refraction, axial length, corneal curvature, white-to-white distance, anterior chamber depth, corneal endothelial cell density, and retinal nerve fiber layer (RNFL) thickness were measured using auto-refractive keratometer, intraocular lens master, noncontact specular microscope, and optical coherence tomography.Result: In correlation analysis, from 19 to 82 years, hyperopic shift showed a strong positive statistical correlation with age (r = 0.553, P < 0.001). Corneal curvatures increased (r = 0.221, P < 0.001), while axial length (r = -0.506, P < 0.001), anterior chamber depth (r = -0.491, P < 0.001) and white-to-white distance (r = -0.205, P < 0.001) decreased with age. Also, -corneal endothelial cell density was lower in older patients than in younger patients (r = -0.409, P < 0.001). Compared to younger patients, RNFL thickness was lower in the older patients as well, in all quadrants (superior, r = -0.283, P < 0.001; inferior, r = -0.230, P < 0.001; nasal, r = 0.025, P = 0.676; and temporal, r = -0.393, P < 0.001). According to multiple regression analysis, out of the six parameters measured, only hyperopic shift, anterior chamber depth and corneal endothelial cell density (P < 0.05) had statistically significant -correlation with age.Conclusion: Some of the ocular parameters changed with aging. Hyperopic shift, shallowing anterior chamber depth, and reduction of corneal endothelial cell density were only definitely related to age.Keywords: corneal endothelial cell density, hyperopic, corneal curvatures, axial length, anterior chamber depth
Limited endoscopic sphincterotomy plus large balloon dilation for choledocholithiasis with periampullary diverticula
Hyung Wook Kim, Dae Hwan Kang, Cheol Woong Choi, Jong Hwan Park, Jin Ho Lee, Min Dae Kim, Il Doo Kim, Ki Tae Yoon, Mong Cho, Ung Bae Jeon, Suk Kim, Chang Won Kim, Jun Woo Lee
World Journal of Gastroenterology , 2010,
Abstract: AIM: To investigate the effectiveness and safety of limited endoscopic sphincterotomy (EST) plus large balloon dilation (LBD) for removing choledocholithiasis in patients with periampullary diverticula (PAD).METHODS: A total of 139 patients with common bile duct (CBD) stones were treated with LBD (10-20 mm balloon diameter) after limited EST. Of this total, 73 patients had PAD and 66 patients did not have PAD (controls). The results of stone removal and complications were retrospectively evaluated.RESULTS: There were no significant differences between the PAD and the control groups in overall successful stone removal (94.5% vs 93.9%), stone removal in first session (69.9% vs 81.8%), mechanical lithotripsy (12.3% vs 13.6%), and complications (11.0% vs 7.6%). Clinical outcomes were also similar between the types of PAD, but the rate of stone removal in first session and the number of sessions were significantly lower and more frequent, respectively, in type B PAD (papilla located near the diverticulum) than controls [23/38 (60.5%) vs 54/66 (81.8%), P = 0.021; and 1 (1-2) vs 1 (1-3), P = 0.037, respectively] and the frequency of pancreatitis was significantly higher in type A PAD (papilla located inside or in the margin of the diverticulum) than in controls (16.1% vs 3.0%, P = 0.047).CONCLUSION: Limited EST plus LBD was an effective and safe procedure for removing choledocholithiasis in patients with PAD. However, some types of PAD should be managed with caution.
Is obesity associated with gastropharyngeal reflux disease?
Cheol Woong Choi, Gwang Ha Kim, Chul Soo Song, Soo Geun Wang, Byung Joo Lee, Hoseok I, Dae Hwan Kang, Geun Am Song
World Journal of Gastroenterology , 2008,
Abstract: AIM: To examine the association between obesity and gastropharyngeal reflux disease (GPRD) as well as gastroesophageal reflux disease (GERD)METHODS: We conducted a cross-sectional study of consecutive patients undergoing ambulatory 24-h dual-probe pH monitoring from July 2003 to December 2006. The association between body mass index (BMI) and parameters about gastroesophageal or gastropharyngeal reflux was examined in univariate and multivariate analyses.RESULTS: A total of 769 patients (307 men and 462 women; mean age 50.7 years) were finally enrolled. Most variables showing gastroesophageal reflux was higher in the obese patients than the patients with normal BMI. There was no difference in all the variables showing gastropharyngeal reflux according to the BMI. After adjustment for age, sex, alcohol intake and smoking, obese patients demonstrated an about 2-fold increase in risk of GERD compared with patients with normal BMI (OR, 1.9; 95 CI, 1.3-2.9), but overweight patients did not demonstrate increased risk of GERD (OR, 1.2; 95 CI, 0.8-1.7). Both obese patients and overweight patients did not demonstrated increased risk of GPRD compared with patients with normal BMI (OR, 1.1; 95 CI, 0.8-1.7; and OR, 0.9; 95 CI, 0.6-1.3, respectively).CONCLUSION: Obesity is not associated with GPRD reflux while it is associated with GERD.
AKARI Infrared Observations of the Supernova Remnant G292.0+1.8: Unveiling Circumstellar Medium and Supernova Ejecta
Ho-Gyu Lee,Bon-Chul Koo,Dae-Sik Moon,Itsuki Sakon,Takashi Onaka,Woong-Seob Jeong,Hidehiro Kaneda,Takaya Nozawa,Takashi Kozasa
Physics , 2009, DOI: 10.1088/0004-637X/706/1/441
Abstract: We present the results of AKARI observations of the O-rich supernova remnant G292.0+1.8 using six IRC and four FIS bands covering 2.7-26.5 um and 50-180 um, respectively. The AKARI images show two prominent structures; a bright equatorial ring structure and an outer elliptical shell structure. The equatorial ring structure is clumpy and incomplete with its western end opened. The outer shell is almost complete and slightly squeezed along the north-south direction. The central position of the outer shell is ~ 1' northwest from the embedded pulsar and coincides with the center of the equatorial ring structure. The equatorial ring and the elliptical shell structures were partly visible in optical and/or X-rays, but they are much more clearly revealed in our AKARI images. There is no evident difference in infrared colors of the two prominent structures, which is consistent with the previous proposition that both structures are of circumstellar origin. However, we have detected faint infrared emission of a considerably high 15 to 24 um ratio associated with the supernova ejecta in the southeastern and northwestern areas. Our IRC spectra show that the high ratio is at least partly due to the emission lines from Ne ions in the supernova ejecta material. In addition we detect a narrow, elongated feature outside the SNR shell. We derive the physical parameters of the infrared-emitting dust grains in the shocked circumstellar medium and compare the result with model calculations of dust destruction by a SN shock. The AKARI results suggest that the progenitor was at the center of the infrared circumstellar shell in red supergiant stage and that the observed asymmetry in the SN ejecta could be a result of either a dense circumstellar medium in the equatorial plane and/or an asymmetric explosion.
Far-Infrared Luminous Supernova Remnant Kes 17
Ho-Gyu Lee,Dae-Sik Moon,Bon-Chul Koo,Takashi Onaka,Woong-Seob Jeong,Jong-Ho Shinn,Itsuki Sakon
Physics , 2011, DOI: 10.1088/0004-637X/740/1/31
Abstract: We present the results of infrared (IR; 2.5--160 um) observations of the supernova remnant (SNR) Kes 17 based on the data obtained with the AKARI and Spitzer satellites. We first detect bright continuum emission of its western shell in the mid- and far-IR wavebands together with its near-IR molecular line emission. We also detect hidden mid-IR emission of its southern shell after subtraction of the background emission in this region. The far-IR luminosity of the western shell is ~ 8100 L_sun, which makes Kes 17 one of the few SNRs of significant far-IR emission. The fittings of the spectral energy distribution indicate the existence of two dust components: ~ 79 K (hot) and ~ 27 K (cold) corresponding to the dust mass of ~ 6.2x10^{-4} M_sun and ~ 6.7 M_sun, respectively. We suggest that the hot component represents the dust emission of the material swept up by the SNR to its western and southern boundaries, compatible with the distribution of radio continuum emission overlapping the mid-IR emission in the western and southern shells. The existence of hot (~ 2,000 K), shocked dense molecular gas revealed by the near-IR molecular line emission in the western shell, on the other hand, suggests that the cold dust component represents the dust emission related to the interaction between the SNR and nearby molecular gas. The excitation conditions of the molecular gas appear to be consistent with those from shocked, clumpy admixture gas of different temperatures. We discuss three possibilities for the origin of the bright far-IR emission of the cold dust in the western shell: the emission of dust in the inter-clump medium of shocked molecular clouds, the emission of dust in evaporating flows of molecular clouds engulfed by hot gas, and the emission of dust of nearby molecular clouds illuminated by radiative shocks.
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