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Search Results: 1 - 10 of 11572 matches for " Phil-Hyun Kang "
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Effect of Addition of Soybean Oil and Gamma-Ray Cross-linking on the Nanoporous HDPE Membrane
Jong-Seok Park,Jong-Bae Choi,Hui-Jeong Gwon,Youn-Mook Lim,Myung Seob Khil,Phil-Hyun Kang,Young-Chang Nho
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/418021
Abstract: A nanoporous high-density polyethylene (HDPE) membrane was prepared by a wet process. Soybean oil and dibutyl phthalate (DBP) were premixed as codiluents, and gamma-rays were used for the cross-linking of HDPE. The pore volume of the nanoporous HDPE membranes with soybean oil was affected by the extracted amount of oil. The tensile strength of the membrane improved with an increasing absorbed dose up to 60 kGy, but decreased at 80 kGy due to severe degradation. The ionic conductivity of the nanoporous HDPE membrane did not really change with an increasing absorbed dose because the pores had already been formed before the gamma-ray radiation. Finally, the electrochemical stability of the HDPE membrane increased when the absorbed dose increased up to 60 kGy.
Valproic Acid Induces Hair Regeneration in Murine Model and Activates Alkaline Phosphatase Activity in Human Dermal Papilla Cells
Soung-Hoon Lee, Juyong Yoon, Seung Ho Shin, Muhamad Zahoor, Hyoung Jun Kim, Phil June Park, Won-Seok Park, Do Sik Min, Hyun-Yi Kim, Kang-Yell Choi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034152
Abstract: Background Alopecia is the common hair loss problem that can affect many people. However, current therapies for treatment of alopecia are limited by low efficacy and potentially undesirable side effects. We have identified a new function for valproic acid (VPA), a GSK3β inhibitor that activates the Wnt/β-catenin pathway, to promote hair re-growth in vitro and in vivo. Methodology/ Principal Findings Topical application of VPA to male C3H mice critically stimulated hair re-growth and induced terminally differentiated epidermal markers such as filaggrin and loricrin, and the dermal papilla marker alkaline phosphatase (ALP). VPA induced ALP in human dermal papilla cells by up-regulating the Wnt/β-catenin pathway, whereas minoxidil (MNX), a drug commonly used to treat alopecia, did not significantly affect the Wnt/β-catenin pathway. VPA analogs and other GSK3β inhibitors that activate the Wnt/β-catenin pathway such as 4-phenyl butyric acid, LiCl, and BeCl2 also exhibited hair growth-promoting activities in vivo. Importantly, VPA, but not MNX, successfully stimulate hair growth in the wounds of C3H mice. Conclusions/ Significance Our findings indicate that small molecules that activate the Wnt/β-catenin pathway, such as VPA, can potentially be developed as drugs to stimulate hair re-growth.
Storing and Searching Metadata for Digital Broadcasting on Set-Top Box Environments  [PDF]
Jong-Hyun Park, Ji-Hoon Kang
Journal of Software Engineering and Applications (JSEA) , 2008, DOI: 10.4236/jsea.2008.11005
Abstract: Digital broadcasting is a novel paradigm for the next generation broadcasting. Its goal is to provide not only better quality of pictures but also a variety of services that is impossible in traditional airwaves broadcasting. One of the important factors for this new broadcasting environment is the interoperability among broadcasting applications since the environment is distributed. Therefore the broadcasting metadata becomes increasingly important and one of the metadata standards for a digital broadcasting is TV-Anytime metadata. TV-Anytime metadata is defined using XML schema, so its instances are XML data. In order to fulfill interoperability, a standard query language is also required and XQuery is a natural choice. There are some researches for dealing with broadcasting metadata. In our previous study, we have proposed the method for efficiently managing the broadcasting metadata in a service provider. However, the environment of a Set-Top Box for digital broadcasting is limited such as low-cost and low-setting. Therefore there are some considerations to apply general approaches for managing the metadata into the Set-Top Box. This paper proposes a method for efficiently managing the broadcasting metadata based on the Set-Top Box and a prototype of metadata management system for evaluating our method. Our system consists of a storage engine to store the metadata and an XQuery engine to search the stored metadata and uses special index for storing and searching. Our two engines are designed independently with hardware platform therefore these engines can be used in any low-cost applications to manage broadcasting metadata.
$B_d-\bar{B}_d$ mixing vs. $B_s-\bar{B}_s$ mixing with the anomalous $Wtb$ couplings
Lee, Jong Phil;Lee, Kang Young
High Energy Physics - Phenomenology , 2008,
Abstract: We explore the effects of the anomalous $tbW$ couplings on the $\bd$ mixing and recently measured $\bs$ mixing. The combined analysis of mixings via box diagrams with penguin decays provides strong constraints on the anomalous top quark couplings. We find the bound from the $\bd$ mixing data is stronger than that from the $\bs$ mixing.
Vehicle License Plate Detection Method Based on Sliding Concentric Windows and Histogram
Kaushik Deb,Hyun-Uk Chae,Kang-Hyun Jo
Journal of Computers , 2009, DOI: 10.4304/jcp.4.8.771-777
Abstract: Detecting the region of a license plate is the key component of the vehicle license plate recognition (VLPR) system. A new method is adopted in this paper to analyze road images which often contain vehicles and extract LP from natural properties by finding vertical and horizontal edges from vehicle region. The proposed vehicle license plate detection (VLPD) method consists of three main stages: (1) a novel adaptive image segmentation technique named as sliding concentric windows (SCWs) used for detecting candidate region; (2) color verification for candidate region by using HSI color model on the basis of using hue and intensity in HSI color model verifying green and yellow LP and white LP, respectively; and (3) finally, decomposing candidate region which contains predetermined LP alphanumeric character by using position histogram to verify and detect vehicle license plate (VLP) region. In the proposed method, input vehicle images are commuted into grey images. Then the candidate regions are found by sliding concentric windows. We detect VLP region which contains predetermined LP color by using HSI color model and LP alphanumeric character by using position histogram. Experimental results show that the proposed method is very effective in coping with different conditions such as poor illumination, varied distances from the vehicle and varied weather.
Rapid and Accurate Multiple Testing Correction and Power Estimation for Millions of Correlated Markers
Buhm Han,Hyun Min Kang,Eleazar Eskin
PLOS Genetics , 2009, DOI: 10.1371/journal.pgen.1000456
Abstract: With the development of high-throughput sequencing and genotyping technologies, the number of markers collected in genetic association studies is growing rapidly, increasing the importance of methods for correcting for multiple hypothesis testing. The permutation test is widely considered the gold standard for accurate multiple testing correction, but it is often computationally impractical for these large datasets. Recently, several studies proposed efficient alternative approaches to the permutation test based on the multivariate normal distribution (MVN). However, they cannot accurately correct for multiple testing in genome-wide association studies for two reasons. First, these methods require partitioning of the genome into many disjoint blocks and ignore all correlations between markers from different blocks. Second, the true null distribution of the test statistic often fails to follow the asymptotic distribution at the tails of the distribution. We propose an accurate and efficient method for multiple testing correction in genome-wide association studies—SLIDE. Our method accounts for all correlation within a sliding window and corrects for the departure of the true null distribution of the statistic from the asymptotic distribution. In simulations using the Wellcome Trust Case Control Consortium data, the error rate of SLIDE's corrected p-values is more than 20 times smaller than the error rate of the previous MVN-based methods' corrected p-values, while SLIDE is orders of magnitude faster than the permutation test and other competing methods. We also extend the MVN framework to the problem of estimating the statistical power of an association study with correlated markers and propose an efficient and accurate power estimation method SLIP. SLIP and SLIDE are available at http://slide.cs.ucla.edu.
Two-Dimensional Axisymmetric Collapse of Thermally Unstable Primordial Clouds
Chang Hyun Baek,Hyesung Kang,Dongsu Ryu
Physics , 2002, DOI: 10.1086/345814
Abstract: We have performed two-dimensional hydrodynamic simulations of the collapse of isolated axisymmetric clouds condensing via radiative cooling in a primordial background gas. In order to study the development of the so-called ``shape-instability'', we have considered two types of axisymmetric clouds, oblate and prolate clouds of various sizes and with axial ratios of $0.5 \leq {R_{\rm c,R}} /{R_{\rm c,z}} \leq 2$. We find that the degree of oblateness or prolateness is enhanced during the initial cooling phase. But it can be reversed later, if the initial contrast in cooling times between the cloud gas and the background gas is much greater than one. In such cases an oblate cloud collapses to a structure composed of an outer thin disk and a central prolate component. A prolate cloud, on the other hand, becomes a thin cigar-shape structure with a central dense oblate component. The reversal of shape in the central part of the cooled clouds is due to supersonic motions either along the disk plane in the case of oblate clouds or along the symmetry axis in the case of prolate clouds. For a background gas of $T_h=1.7\times 10^6$K and $n_h=0.1 \cm3$ in a protogalactic halo environment, the mean density of the cloud gas that has cooled to $10^4$K increases to $100 n_h$ or so, in our simulations where nonequilibrium cooling is adopted and the background gas cools too. The spherical Jeans mass of such gas is estimated to be about $M_J \sim 5\times10^{7}\Msun$. In order for cloud mass to exceed the Jeans mass and at the same time in order for the thermal instability to operate, the initial cloud size should be around $1 - 1.5 l_{\rm cool}$ where $l_{\rm cool}$ is the cooling length.
The GDOF of 3-user MIMO Gaussian interference channel
Jung Hyun Bae,Jungwon Lee,Inyup Kang
Mathematics , 2012,
Abstract: The paper establishes the optimal generalized degrees of freedom (GDOF) of 3-user $M \times N$ multiple-input multiple-output (MIMO) Gaussian interference channel (GIC) in which each transmitter has $M$ antennas and each receiver has $N$ antennas. A constraint of $2M \leq N$ is imposed so that random coding with message-splitting achieves the optimal GDOF. Unlike symmetric case, two cross channels to unintended receivers from each transmitter can have different strengths, and hence, well known Han-Kobayashi common-private message splitting would not achieve the optimal GDOF. Instead, splitting each user's message into three parts is shown to achieve the optimal GDOF. The capacity of the corresponding deterministic model is first established which provides systematic way of determining side information for converse. Although this deterministic model is philosophically similar to the one considered by Gou and Jafar, additional constraints are imposed so that capacity description of the deterministic model only contains the essential terms for establishing the GDOF of Gaussian case. Based on this, the optimal GDOF of Gaussian case is established with $\mathcal{O}(1)$ capacity approximation. The behavior of the GDOF is interestingly different from that of the corresponding symmetric case. Regarding the converse, several multiuser outer bounds which are suitable for asymmetric case are derived by non-trivial generalization of the symmetric case.
Outage-based ergodic link adaptation for fading channels with delayed CSIT
Jung Hyun Bae,Jungwon Lee,Inyup Kang
Mathematics , 2012,
Abstract: Link adaptation in which the transmission data rate is dynamically adjusted according to channel variation is often used to deal with time-varying nature of wireless channel. When channel state information at the transmitter (CSIT) is delayed by more than channel coherence time due to feedback delay, however, the effect of link adaptation can possibly be taken away if this delay is not taken into account. One way to deal with such delay is to predict current channel quality given available observation, but this would inevitably result in prediction error. In this paper, an algorithm with different view point is proposed. By using conditional cdf of current channel given observation, outage probability can be computed for each value of transmission rate $R$. By assuming that the transmission block error rate (BLER) is dominated by outage probability, the expected throughput can also be computed, and $R$ can be determined to maximize it. The proposed scheme is designed to be optimal if channel has ergodicity, and it is shown to considerably outperform conventional schemes in certain Rayleigh fading channel model.
On the achievable region for interference networks with point-to-point codes
Jung Hyun Bae,Jungwon Lee,Inyup Kang
Mathematics , 2013,
Abstract: This paper studies evaluation of the capacity region for interference networks with point-to-point (p2p) capacity-achieving codes. Such capacity region has recently been characterized as union of several sub-regions each of which has distinctive operational characteristics. Detailed evaluation of this region, therefore, can be accomplished in a very simple manner by acknowledging such characteristics, which, in turn, provides an insight for a simple implementation scenario. Completely generalized message assignment which is also practically relevant is considered in this paper, and it is shown to provide strictly larger achievable rates than what traditional message assignment does when a receiver with joint decoding capability is used.
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