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Search Results: 1 - 10 of 20547 matches for " Heung Up Kim "
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Duodenal obstruction after successful embolization for duodenal diverticular hemorrhage: A case report
Yu Jin Kwon, Ji Hun Kim, Seung Hyoung Kim, Bong Soo Kim, Heung Up Kim, Eun Kwang Choi, In Ho Jeong
World Journal of Gastroenterology , 2009,
Abstract: We present a 69-year-old woman with a duodenal obstruction after successful selective transcatheter arterial embolization (TAE) for a duodenal diverticular hemorrhage. Two weeks after TAE, the patient showed abrupt symptoms of duodenal obstruction. Resolving hematomas after successful selective transcatheter arterial embolization should be thoroughly observed because they might result in duodenal fibrotic encasement featuring inflammatory duodenal wall thickening, duodenal deformity, dysmotility, and finally obstruction.
Perceived Organizational Support, Job Satisfaction and Employee Performance: An Chinese Empirical Study  [PDF]
Rentao Miao, Heung-Gil Kim
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.32032
Abstract: The study investigated the generalizability of perceived organizational support and job satisfaction as positive correlations of employee performance in China. In a study conducted, 130 matched cases of 130 employees and their 34 immediate supervisors from two large-scale state-owned enterprises (SOE) were selected as participants. Well-established psychological scales measuring perceived organizational support (POS), job satisfaction, and four facets of organizational citizenship behavior (OCB) were administered. Data analyzed using zero-order correlation and hierarchical regression analysis showed positive correlations of POS and job satisfaction with work performance, and also showed independent and joint positive associations of POS and job satisfaction with OCB and each of its four dimensions.
Effect of charge doping on the electronic structure, orbital polarization, and structural distortion in nickelate superlattice
Heung-Sik Kim,Myung Joon Han
Physics , 2013, DOI: 10.1103/PhysRevB.91.235102
Abstract: Using first-principles density functional theory calculations, we investigated the effect of charge doping in a LaNiO$_3$/SrTiO$_3$ superlattice. The detailed analysis based on two different simulation methods for doping clearly shows that the electronic and structural properties change in a systematic way that the orbital polarization ({\it i.e.} relative occupation of two Ni-$e_g$ orbitals) is reduced and the Ni to apical oxygen distance enlarged as the number of doped electrons increases. Also, the rotation angles of the NiO$_6$/TiO$_6$ octahedra strongly and systematically depend on the doping so that the angle $\gamma$ gradually decreases whereas the $\alpha$ and $\beta$ increase as a function of electron doping. Further analysis shows that the electron (hole) doping can play a similar role with the compressive (tensile) strain for the octahedral rotations. Our results not only suggest a possible way to control the orbital and structural property by means of charge doping, but also provide useful information to understand the experiments under various doping situations such as oxygen vacancy.
Detection-Directed Sparse Estimation using Bayesian Hypothesis Test and Belief Propagation
Jaewook Kang,Heung-No Lee,Kiseon Kim
Mathematics , 2012,
Abstract: In this paper, we propose a sparse recovery algorithm called detection-directed (DD) sparse estimation using Bayesian hypothesis test (BHT) and belief propagation (BP). In this framework, we consider the use of sparse-binary sensing matrices which has the tree-like property and the sampled-message approach for the implementation of BP. The key idea behind the proposed algorithm is that the recovery takes DD-estimation structure consisting of two parts: support detection and signal value estimation. BP and BHT perform the support detection, and an MMSE estimator finds the signal values using the detected support set. The proposed algorithm provides noise-robustness against measurement noise beyond the conventional MAP approach, as well as a solution to remove quantization effect by the sampled-message based BP independently of memory size for the message sampling. We explain how the proposed algorithm can have the aforementioned characteristics via exemplary discussion. In addition, our experiments validate such superiority of the proposed algorithm, compared to recent algorithms under noisy setup. Interestingly the experimental results show that performance of the proposed algorithm approaches that of the oracle estimator as SNR becomes higher.
Phase Transition Analysis of Sparse Support Detection from Noisy Measurements
Jaewook Kang,Heung-No Lee,Kiseon Kim
Mathematics , 2013,
Abstract: This paper investigates the problem of sparse support detection (SSD) via a detection-oriented algorithm named Bayesian hypothesis test via belief propagation (BHT-BP). Our main focus is to compare BHT-BP to an estimation-based algorithm, called CS-BP, and show its superiority in the SSD problem. For this investigation, we perform a phase transition (PT) analysis over the plain of the noise level and signal magnitude on the signal support. This PT analysis sharply specifies the required signal magnitude for the detection under a certain noise level. In addition, we provide an experimental validation to assure the PT analysis. Our analytical and experimental results show the fact that BHT-BP detects the signal support against additive noise more robustly than CS-BP does.
Bayesian Hypothesis Test for Sparse Support Recovery using Belief Propagation
Jaewook Kang,Heung-No Lee,Kiseon Kim
Mathematics , 2012,
Abstract: In this paper, we introduce a new support recovery algorithm from noisy measurements called Bayesian hypothesis test via belief propagation (BHT-BP). BHT-BP focuses on sparse support recovery rather than sparse signal estimation. The key idea behind BHT-BP is to detect the support set of a sparse vector using hypothesis test where the posterior densities used in the test are obtained by aid of belief propagation (BP). Since BP provides precise posterior information using the noise statistic, BHT-BP can recover the support with robustness against the measurement noise. In addition, BHT-BP has low computational cost compared to the other algorithms by the use of BP. We show the support recovery performance of BHT-BP on the parameters (N; M; K; SNR) and compare the performance of BHT-BP to OMP and Lasso via numerical results.
Bayesian Hypothesis Test using Nonparametric Belief Propagation for Noisy Sparse Recovery
Jaewook Kang,Heung-No Lee,Kiseon Kim
Mathematics , 2015, DOI: 10.1109/TSP.2014.2385659
Abstract: This paper proposes a low-computational Bayesian algorithm for noisy sparse recovery (NSR), called BHT-BP. In this framework, we consider an LDPC-like measurement matrices which has a tree-structured property, and additive white Gaussian noise. BHT-BP has a joint detection-and-estimation structure consisting of a sparse support detector and a nonzero estimator. The support detector is designed under the criterion of the minimum detection error probability using a nonparametric belief propagation (nBP) and composite binary hypothesis tests. The nonzeros are estimated in the sense of linear MMSE, where the support detection result is utilized. BHT-BP has its strength in noise robust support detection, effectively removing quantization errors caused by the uniform sampling-based nBP. Therefore, in the NSR problems, BHT-BP has advantages over CS-BP which is an existing nBP algorithm, being comparable to other recent CS solvers, in several aspects. In addition, we examine impact of the minimum nonzero value of sparse signals via BHT-BP, on the basis of the results of the recent literature. Our empirical result shows that variation of x_min is reflected to recovery performance in the form of SNR shift.
On Detection-Directed Estimation Approach for Noisy Compressive Sensing
Jaewook Kang,Heung-No Lee,Kiseon Kim
Mathematics , 2012,
Abstract: In this paper, we investigate a Bayesian sparse reconstruction algorithm called compressive sensing via Bayesian support detection (CS-BSD). This algorithm is quite robust against measurement noise and achieves the performance of a minimum mean square error (MMSE) estimator that has support knowledge beyond a certain SNR threshold. The key idea behind CS-BSD is that reconstruction takes a detection-directed estimation structure consisting of two parts: support detection and signal value estimation. Belief propagation (BP) and a Bayesian hypothesis test perform support detection, and an MMSE estimator finds the signal values belonging to the support set. CS-BSD converges faster than other BP-based algorithms, and it can be converted to a parallel architecture to become much faster. Numerical results are provided to verify the superiority of CS-BSD compared to recent algorithms.
Transient elastography in chronic hepatitis B: An Asian perspective
Seung Up Kim, Kwang-Hyub Han, Sang Hoon Ahn
World Journal of Gastroenterology , 2010,
Abstract: Transient elastography (TE) is a new non-invasive tool for assessing liver stiffness, which is correlated with the histologic stage of liver fibrosis. Many studies have reported a good accuracy of TE in predicting significant fibrosis and an optimal accuracy in predicting cirrhosis. Furthermore, the potential role of TE in screening the general population has also been proven. TE thus helps physicians to decide treatment strategies, predict prognosis, and monitor disease progression in patients with chronic liver disease and to screen the general population to identify high risk patients with potential liver disease. However, most data on the clinical roles of TE have been gathered in European patients with chronic hepatitis C (CHC), because TE was first developed in France. Accordingly, much data on the usefulness of TE in patients with CHC has accumulated. Recently, however, vigorous efforts have been made to apply TE to patients with chronic hepatitis B (CHB), and TE has also proved to have acceptable accuracy in diagnosing liver fibrosis and cirrhosis in these patients. Thus, we focused on TE in the Asian population with CHB in comparison with the European population with CHC and found that the diagnostic performance and cutoff values were different between the 2 populations possibly as a result of several different confounders between Asian and European populations (the etiology of chronic liver disease, histologic features, major fluctuation in alanine aminotransferase levels, and the prevalence of high body mass index and metabolic syndrome). Therefore, further studies tailored to the Asian population with CHB should be performed before the widespread application of TE in Asian populations with CHB.
Assessment of genetic diversity of Typha angustifolia in the development of cattail stands
So Jung Min,Heung-Tae Kim,Jae Geun Kim*
Journal of Ecology and Field Biology , 2012,
Abstract: Typha angustifolia has ecological characteristics of clonal growth similar to Phragmites australis. The plant spreads byclonal growth and seed dispersal. In this study, for the three stands which have different settlement age at the Baksiljiwetland in Korea, genetic diversity was estimated by random amplification of polymorphic DNA analysis to evaluate thechange in genetic diversity of T. angustifolia during stand development in the same population. Stand (ST) 1 was the oldestand ST 4 was the youngest. ST 5 was in a small ditch out of the Baksilji. Although the ST 1, ST 2, and ST 3 did not differsignificantly in vegetational or physical environment, the genetic diversity estimated according to Nei’s gene diversity(h) and the Shannon index (i) increased in the order of ST 1 < ST 2 < ST 3 contrary to formative age. The genetic diversityof ST 4 was much higher than that of the other three stands. ST 4 has similar abiotic environmental conditions withslight T. angustifolia dominance, and seems to be in the early establishment stage. ST 5 differed from the other stands invegetational and soil environments, which can result in stressful cattail conditions. Even though the ST 5 stand was notyounger than the ST 4 stand, ST 5 showed the highest genetic diversity. Our results indicate that after early settlement ofthe T. angustifolia population, genetic diversity within the species decreased over time and that the decreasing pattern ofgenetic diversity within T. angustifolia stands is not likely to occur under stressful conditions.
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