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Search Results: 1 - 10 of 3293 matches for " Joon Jeong "
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Interface Reactions and Synthetic Reaction of Composite Systems
Joon Sik Park,Jeong Min Kim
Materials , 2010, DOI: 10.3390/ma3010264
Abstract: Interface reactions in composite systems often determine their overall properties, since product phases usually formed at interfaces during composite fabrication processing make up a large portion of the composites. Since most composite materials represent a ternary or higher order materials system, many studies have focused on analyses of diffusion phenomena and kinetics in multicomponent systems. However, the understanding of the kinetic behavior increases the complexity, since the kinetics of each component during interdiffusion reactions need to be defined for interpreting composite behaviors. From this standpoint, it is important to clarify the interface reactions for producing compatible interfaces with desired product phases. A thermodynamic evaluation such as a chemical potential of involving components can provide an understanding of the diffusion reactions, which govern diffusion pathways and product phase formation. A strategic approach for designing compatible interfaces is discussed in terms of chemical potential diagrams and interface morphology, with some material examples.
Reference-based fair MAC algorithm in Wi-Fi WLANs with capture effect
Jiwoong Jeong, Sunwoong Choi and Joon Yoo
EURASIP Journal on Wireless Communications and Networking , 2013, DOI: 10.1186/1687-1499-2013-50
Abstract: The widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Due to the inherent characteristics of the wireless medium in WLAN systems, the capture effect significantly affects the system performance; a receiver can successfully decode a collided frame given that its signal-to-interference and noise ratio is sufficiently high enough, but results in an unfair channel access share among the wireless nodes. In this article, we propose fair capture effect aware MAC (FC-MAC) algorithm, which achieves channel access fairness using a feedback control mechanism. We determine the average waiting time as a common control reference, which provides fair channel access even when the capture effect is present. In result, the algorithm enables each node to converge to a fair channel access share. Among multiple points that yields fair channel access, we determine the optimal target reference that maximizes the aggregate throughput. Through both dynamic system modeling and extensive simulation studies, we show that the FC-MAC algorithm is stable and achieves fairness while improving the aggregate throughput.
Recursive Implementation of Natural Frequency-Based Radar Detection Using the Lrt Scheme
Joon-Ho Lee;So-Hee Jeong
PIER , 2013, DOI: 10.2528/PIER13011701
Abstract: We address the performance analysis of the natural frequency-based radar target detection in this paper. We show how to calculate the detection performance recursively by making a polynomial approximation of the probability density function (PDF) of the standard normal distribution. Why we make a polynomial approximation of the PDF of the standard normal distribution is that the PDF of the standard normal distribution is not analytically integrable but that the polynomial is definitely analytically integrable, which makes it possible to calculate the detection performance without look-up table. The Taylor polynomial is used for an approximation of the PDF of the standard normal distribution. We derive the error of the approximation, the bound of the error of approximation, and the optimal polynomial approximation in the sense that the bound of the error of the approximation is minimized. We validate the derived expressions via numerical simulation.
Increased expression of oxyproteins in the optic nerve head of an in vivo model of optic nerve ischemia
Kim Joon Mo,Kim Yu Jeong,Kim Dong Myung
BMC Ophthalmology , 2012, DOI: 10.1186/1471-2415-12-63
Abstract: Background To investigate the effects of microvascular compromise on the expression of oxidative proteins in the optic nerve head. Methods Endothelin-1 (0.1 μg/day) was delivered to the perineural region of the anterior optic nerve by osmotically driven minipumps for two, four, and eight weeks in ten rabbits, respectively. As a control, a balanced salt solution was delivered for two and eight weeks in five rabbits, respectively. Expression of oxyproteins in the cornea, vitreous, retina, and optic nerve head for each time period was determined using the OxyBlot protein oxidation detection kit. Retina was stained with H&E and TUNEL for histological examination. Results There was a significant increase in the expression of oxyproteins in the optic nerve head after two weeks of endothelin-1 administration (p < 0.001, Mann Whitney U test). In contrast, there was no expression of oxyproteins in the cornea, retina, or vitreous. The number of cells in the retinal ganglion cell layer, inner nuclear layer, and outer nuclear layer decreased remarkably with time in the endothelin-1-treated group. Furthermore, the inner and outer nuclear layers, as well as the inner and outer plexiform layers, became thinner over time. Conclusions Administration of endothelin-1 to the microvasculature of the optic nerve leads to increased expression of oxyproteins in the optic nerve head and loss of retinal ganglion cells.
An Auto-Configuration of 4M Group Management Using Wireless Sensor Networks  [PDF]
Suk-Keun Cha, Jeong-Hoon Lee, Han Gyu Kim, Joon Jae Yoo, Jung Hoon Kang, Dong Hoon Kim, Jun Yeob Song
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.24052
Abstract: The first tier of automotive manufacturers has faced to pressures about move, modify, updating tasks for manufacturing resources in production processes from demand response of production order sequence for motor company and process innovation purpose for productivity. For meets this requirements, it has to require absolutely lead time to re-wiring of physical interface for production equipment, needs for change existing program and test over again. For prepare this constraints, it needs studying an auto-configuration functions that build for both visibility and flexibility based on the 4M (Man, Machine, Material, Method) group management which is supports from WSN (Wireless Sensor Network) of the open embedded device called M2M (Machine to Machine) and major functions of middleware including point manager for real-time device communication, real-time data management, Standard API (Application Program Interface) and application template management. To be application system to RMS (Reconfigurable Manufacturing System) for rapidly response from various orders and model from motor company that is beginning to establishing the mapping of manufacturing resources of 4M using WSN.
NUNS: A Nonuniform Network Split Method for Data-Centric Storage Sensor Networks
Ki-Young Lee,Hong-Koo Kang,In-Su Shin,Jeong-Joon Kim,Ki-Joon Han
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/659235
Abstract: If data have the same value frequently in a data-centric storage sensor network, then the load is concentrated on a specific sensor node and the node consumes energy rapidly. In addition, if the sensor network is expanded, the routing distance to the target sensor node becomes longer in data storing and query processing, and this increases the communication cost of the sensor network. This paper proposes a nonuniform network split(NUNS) method that distributes the load among sensor nodes in data-centric storage sensor networks and efficiently reduces the communication cost of expanding sensor networks. NUNS splits a sensor network into partitions of nonuniform sizes in a way of minimizing the difference in the number of sensor nodes and in the size of partitions, and it stores data occurring in each partition in the sensor nodes of the partition. In addition, NUNS splits each partition into zones of nonuniform sizes as many as the number of sensor nodes in the partition in a way of minimizing the difference in the size of the split zones and assigns each zone to the processing area of each sensor node. Finally, we performed various performance evaluations and proved the superiority of NUNS to existing methods.
Aggregate Queries in Wireless Sensor Networks
Jeong-Joon Kim,In-Su Shin,Yan-Sheng Zhang,Dong-Oh Kim,Ki-Joon Han
International Journal of Distributed Sensor Networks , 2012, DOI: 10.1155/2012/625798
Abstract: Recently as efficient processing of aggregate queries for fetching desired data from sensors has been recognized as a crucial part, in-network aggregate query processing techniques are studied intensively in wireless sensor networks. Existing representative in-network aggregate query processing techniques propose routing algorithms and data structures for processing aggregate queries. However, these aggregate query processing techniques have problems such as high energy consumption in sensor nodes, low accuracy of query processing results, and long query processing time. In order to solve these problems and to enhance the efficiency of aggregate query processing in wireless sensor networks, this paper proposes Bucket-based Parallel Aggregation (BPA). BPA divides a query region into several cells according to the distribution of sensor nodes and builds a quadtree, and then processes aggregate queries in parallel for each cell region according to routing. It sends data in duplicate by removing redundant data, which, in turn, enhances the accuracy of query processing results. Also, BPA uses a bucket-based data structure in aggregate query processing, and divides and conquers the bucket data structure adaptively according to the number of data in the bucket. In addition, BPA compresses data in order to reduce the size of data in the bucket and performs data transmission filtering when each sensor node sends data. Finally, in this paper, we prove its superiority through various experiments using sensor data.
Effect of the H1N1 Influenza Pandemic on the Incidence of Epidemic Keratoconjunctivitis and on Hygiene Behavior: A Cross-Sectional Study
Hyun Su Kim, Ho Chun Choi, Belong Cho, Joon Yong Lee, Min Jeong Kwon
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023444
Abstract: Background EKC is transmitted chiefly by direct hand contact. It is suspected that the 2009/2010 influenza pandemic influenced hand washing. This study aims to examine the relationship between the 2009/2010 H1N1 influenza pandemic and hygiene behavior. Methods We compared the EKC prevalence trends before, during and after the 2009/2010 influenza pandemic by using a t-test comparison of EKC sentinel surveillance. Results During the pre-pandemic period, the incidence of EKC increased from the 21st to the 44th week each year. However, during the pandemic period in 2009, there was no epidemic peak. In the post-pandemic period, the epidemic curve was similar to that in the pre-pandemic period. Compared to the pre-pandemic period, the total number of EKC patients during the pandemic period showed a decrease of 44.9% (t value = ?7.23, p = 0.002). Comparing the pre-pandemic and pandemic periods by age group, we found there to be a significant decrease in the number of EKC patients for all age groups (?4.12≤t value≤?7.23, all P<0.05). This finding was most evident in the teenage group (62%) compared to the other age groups (decreases of 29 to 44%). Conclusions A continuing effort should be made to educate the public on basic infection prevention behaviors in the aftermath of the pandemic, particularly to teenagers.
Identification of Type 2 Diabetes-associated combination of SNPs using Support Vector Machine
Hyo-Jeong Ban, Jee Yeon Heo, Kyung-Soo Oh, Keun-Joon Park
BMC Genetics , 2010, DOI: 10.1186/1471-2156-11-26
Abstract: We analyzed the importance of gene-gene interactions in T2D susceptibility by investigating 408 single nucleotide polymorphisms (SNPs) in 87 genes involved in major T2D-related pathways in 462 T2D patients and 456 healthy controls from the Korean cohort studies. We evaluated the support vector machine (SVM) method to differentiate between cases and controls using SNP information in a 10-fold cross-validation test. We achieved a 65.3% prediction rate with a combination of 14 SNPs in 12 genes by using the radial basis function (RBF)-kernel SVM. Similarly, we investigated subpopulation data sets of men and women and identified different SNP combinations with the prediction rates of 70.9% and 70.6%, respectively. As the high-throughput technology for genome-wide SNPs improves, it is likely that a much higher prediction rate with biologically more interesting combination of SNPs can be acquired by using this method.Support Vector Machine based feature selection method in this research found novel association between combinations of SNPs and T2D in a Korean population.It is estimated that by the year 2030, there will be ~366 million people affected by Type 2 diabetes (T2D) worldwide [1], with many of those affected lying in the middle to late adult years group [2]. T2D is genetically heterogeneous disease by the complex interplay of several environmental factors and susceptibility genes [3]. Single-nucleotide polymorphism (SNP) exhibits an abundant form of genetic variations. SNPs can be distinguished from other rare variations by more than 1% frequency in the human population when a single nucleotide replaces one of the three nucleotides. The human genome contains about 10~30 million SNPs with an average SNP every 100~300 bases. More than 5 million human SNPs have been identified and the information is publicly available (NCBI dbSNP Build 129). A SNP in a protein coding sequence (CDS) can induce amino acid changes, resulting in functional changes in the protein. Some SNP
An outbreak of post-acupuncture cutaneous infection due to Mycobacterium abscessus
Joon Song, Jang Sohn, Hye Jeong, Hee Cheong, Woo Kim, Min Kim
BMC Infectious Diseases , 2006, DOI: 10.1186/1471-2334-6-6
Abstract: Patients were defined as clinic patients with persistent cutaneous infections at the acupuncture sites. Medical records for the previous 7 months were reviewed. Clinical specimens were obtained from the patients and an environmental investigation was performed. M. abscessus isolates, cultured from patients, were compared by pulsed-field gel electrophoresis (PFGE).Forty patients who attended the Oriental medicine clinic and experienced persistent cutaneous wound infections were identified. Cultures from five of these patients proved positive, and all other diagnoses were based on clinical and histopathologic examinations. All environmental objects tested were negative for M. abscessus, however, most were contaminated by various nosocomial pathogens. Molecular analysis using PFGE found all wound isolates to be identical.We have identified a large outbreak of rapidly growing mycobacterial infection among patients who received acupuncture at a single Oriental medicine clinic. Physicians should suspect mycobacterial infections in patients with persistent cutaneous infections following acupuncture, and infection control education including hygienic practice, should be emphasized for Oriental medical doctors practicing acupuncture.Acupuncture has become increasingly accepted as a form of alternative medicine in Western countries, though it has been practiced for hundreds of years by Oriental medical doctors in South Korea. As of 2002, about 13,000 Oriental medical doctors were licensed through the national examination for medical practice. These practitioners are recognized as a type of medical doctor by the South Korean public, however, Oriental medical doctors and other medical doctors are educated, and subsequently practice, in a separate system. Therefore, Oriental medical doctors are relatively unfamiliar with infection control, and usually see patients in general office rooms.Acupuncture can be complicated by infections caused by environmental microorganisms or patie
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