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Search Results: 1 - 10 of 1965 matches for " Hwan Joo "
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Periodically time-varying memory static output feedback control design for discrete-time LTI systems
Dong Hwan Lee,Young Hoon Joo,Myung Hwan Tak
Mathematics , 2014,
Abstract: This paper addresses the problem of static output feedback (SOF) stabilization for discrete-time LTI systems. We approach this problem using the recently developed periodically time-varying memory state-feedback controller (PTVMSFC) design scheme. A bilinear matrix inequality (BMI) condition which uses a pre-designed PTVMSFC is developed to design the periodically time-varying memory SOF controller (PTVMSOFC). The BMI condition can be solved by using BMI solvers. Alternatively, we can apply two-steps and iterative linear matrix inequality algorithms that alternate between the PTVMSFC and PTVMSOFC designs. Finally, an example is given to illustrate the proposed methods.
Biodiesel Resistance of Thin Resin Cr-Free Steel Sheets for Fuel Tank  [PDF]
Dong-Joo Yoon, Kyung-Hwan Lee, Jong-Geun Choi, Sangkeol Noh, Jongsang Kim
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.35057
Abstract: The content of biodiesel mixed with diesel fuel were compared to inspect the fuel resistance of thin resin Cr-free steel sheets, which are widely used as steel sheets of automobile fuel tank. Some additives which can be presented during the process of biodiesel preparation were added for CCT (Cyclic Corrosion Test). These additives can accelerate the occurrence of corrosion. The corrosion was appeared on the coating and painting layer and in serious cases even substrate material was corroded. For methanol, mixing with blended fuel showed the reduction in corroded area as the additive concentration was reduced in the mixed fuel. Especially the peroxide hydrogen showed the strongest corrosiveness. It is known that formic acid has a tendency of weaker corrosiveness than peroxide hydrogen, but the corrosion is occurred throughout the specimen. Water is not mixed well with fuel, and does not seem to impact on corrosion significantly. However, water is easily mixed with other additives and is considered to facilitate the corrosion by other additives.
Comparative Genome Analysis and Phylogenetic Relationship of Order Liliales Insight from the Complete Plastid Genome Sequences of Two Lilies (Lilium longiflorum and Alstroemeria aurea)
Jung Sung Kim, Joo-Hwan Kim
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0068180
Abstract: Monocots are one of the most diverse, successful and economically important clades of angiosperms. We attempt to analyse the complete plastid genome sequences of two lilies and their lengths were 152,793bp in Lilium longiflorum (Liliaceae) and 155,510bp in Alstroemeria aurea (Alstroemeriaceae). Phylogenetic analyses were performed for 28 taxa including major lineages of monocots using the sequences of 79 plastid genes for clarifying the phylogenetic relationship of the order Liliales. The sister relationship of Liliales and Asparagales-commelinids was improved with high resolution. Comparative analyses of inter-familial and inter-specific sequence variation were also carried out among three families of Liliaceae, Smilacaceae, and Alstroemeriaceae, and between two Lilium species of L. longflorum and L. superbum. Gene content and order were conserved in the order Liliales except infA loss in Smilax and Alstroemeria. IR boundaries were similar in IRa, however, IRb showed different extension patterns as JLB of Smilax and JSB in Alstroemeria. Ka/Ks ratio was high in matK among the pair-wise comparison of three families and the most variable genes were psaJ, ycf1, rpl32, rpl22, matK, and ccsA among the three families and rps15, rpoA, matK, and ndhF between Lilium.
Cognitive Profiles and Subtypes of Patients with Mild Cognitive Impairment: Data from a Clinical Follow-Up Study  [PDF]
Kyung Won Park, Eun-Joo Kim, Hwan Joo, Sung-Man Jeon, Seong-Ho Choi, Jay C. Kwon, Byoung Gwon Kim, Jae Woo Kim
International Journal of Clinical Medicine (IJCM) , 2012, DOI: 10.4236/ijcm.2012.35068
Abstract: Background: Mild cognitive impairment (MCI) is a heterogeneous condition with a variety of clinical outcomes, the presence of which correlates with risk of Alzheimer’s disease as well as pre-clinical stages of other dementia subtypes. The aims of this study were to assess the specific patterns of cognitive profiles and to identify changes from baseline to 24 weeks in patients with MCI using detailed neuropsychological testing. Methods: We consecutively recruited 120 MCI patients at baseline according to the Petersen’s clinical diagnostic criteria, who were admitted to the Dementia and Memory Clinics. We analyzed patients who fulfilled both inclusion and exclusion criteria for MCI and classified them into four subtypes according to deficits in major cognitive domains; amnestic MCI single domain (aMCI-s), amnestic multiple domain MCI (aMCI-m), non-amnestic single domain MCI (naMCI-s) and non-amnestic multiple domain MCI (naMCI-m). Four groups of MCI were evaluated by a detailed neuropsychological battery test. Results: 83 patients with MCI at the 24-week follow-up were classified into four subtypes. The most frequent subtype was amnestic multi-domain MCI, with the frequency of MCI subtypes as follows: aMCI-s (n = 21, 25.3%), aMCI-m (n = 53, 63.9%), naMCI-s (n = 5, 6.0%) and naMCI-m (n = 4, 4.8%). In the major cognitive items of the SNSB-D, there were significant changes between the initial and follow-up tests in the domains of language, memory and the fron-tal/executive function (p < 0.05), except for attention, in all MCI patient subtypes. At 24-weeks follow-up, the conversion rate to Alzheimer’s disease was 2.4% (n = 2) from a subtype of amnestic multi-domain MCI. Conclusions: Our study revealed the most frequent subtype of MCI to be multiple domain amnestic MCI, with this subtype having a higher tendency of conversion to Alzheimer’s disease.
ATMOSPHERIC CORRECTION OF THE LANDSAT SATELLITE IMAGERY FOR TURBID WATERS
Hwan Ahn,Yu; Shanmugam,P; Hyung Ryu,Joo;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000200002
Abstract: this paper describes methods for the correction of the atmospheric effects in the landsat vis/nir imagery in relation to the retrieval of meaningful information about the ocean color, especially from case-2 waters around korean peninsula. three atmospheric correction (ac) methods implemented and examined, using the toa radiance or reflectance data, are 6s radiative transfer model, spectral shape matching (ssmm) and path-extraction methods. the results show that overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected landsat vis/nir imagery by ssmm appears to have very good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero values for the black ocean pixels of the landsat vis/nir bands. because of the standard atmosphere with constant aerosols and models adopted in 6s model, a large error is possible between the retrieved and in-situ spectra. validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of classical ac algorithms, but is feasible with ssmm.
MONITOR SPATIAL AND TEMPORAL PATTERNS OF SUSPENDED SEDIMENTS IN THE EAST CHINA AND YELLOW SEAS USING SEAWIFS DATA
Hyung Ryu,Joo; Hwan Ahn,Yu; Shanmugam,P.;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000300036
Abstract: striking patterns of suspended sediments created by a complex interplay of physical, chemical, biological and geological processes in the east china sea (ecs) and yellow sea (ys) have been investigated using seawifs ocean color imagery. the structure of these patterns can reveal a great deal about the processes underlying their formation. sea surface temperature (sst) analyzed from the advanced very high resolution radiometer (avhrr) thermal infrared data and in-situ were used to elucidate the physical factors responsible for the evolution of such patterns in the inner and outer selves areas, whilst concomitant patterns of suspended sediment were tracked from the sea-viewing wide field-of-view sensor (seawifs) ocean color imagery. a careful analysis of these patterns in conjugation with other data gave birth to the definition of the evolution of suspended sediments (ss) into four stages: (1) infant stage, (2) younger stage, (3) mature stage and (4) old stage. each of these stages experiences the different characteristics of waters and numerous physical mechanisms that control pattern formation during the winter monsoon. vertical and horizontal profiles of suspended sediments appear to be useful in predicting the evolution of these stages, of these, the younger stage is identified as important candidate to represent the intrusion of yellow sea warm current (yswc) to the northwest of the jeju-island
ANALYSIS OF LAND SAT-5 TM IMAGERY FOR EXTRACTING AQUACULTURE FARMS INFORMATION IN THE KOREAN COASTAL WATERS
Shanmugam,P.; Ahn,Yu-Hwan; Hyung Ryu,Joo;
Gayana (Concepción) , 2004, DOI: 10.4067/S0717-65382004000300038
Abstract: the objective of the present study is to compare certain conventional satellite image processing techniques with the recently evolved linear spectral unmixing method and to ascertain the best possible technique that can identify and position of aquaculture farms accurately in and around the younggwang coastal region of korea. various conventional techniques existed to extract such information are spectral enhancement and classification. however, these techniques performed on the landsat-tm imagery do not seem to yield accurate information about the aquaculture farms, and instead lead to misinterpretation and misclassification. a large discrepancy between the actual and extracted information results from spectral confusion and inadequate spatial resolution of the sensor, which leads to occurrence of mixture pixels or "mixels", which are known to be the source of errors in the classified image. to over come this problem, more recently evolved methods such as step-by-step iterative partial spectral end-member extraction linear spectral unmixing methods are attempted. large errors in extraction of aquaculture farms information through the conventional classification techniques are significantly minimized with the step-by-step iterative partial spectral end-member extraction approach and the accuracy of classification is further improved with linear spectral unmixing approach. the aquaculture fraction derived from unmxing of tm image data was validated using ndvi values in absence of field data. ndvi and aquaculture fraction are positively correlated (r2 = 0.91), indicating the reliability of the sub-pixel classification
ANALYSIS OF LAND SAT-5 TM IMAGERY FOR EXTRACTING AQUACULTURE FARMS INFORMATION IN THE KOREAN COASTAL WATERS
P. Shanmugam,Yu-Hwan Ahn,Joo Hyung Ryu
Gayana (Concepción) , 2004,
Abstract: The objective of the present study is to compare certain conventional satellite image processing techniques with the recently evolved linear spectral unmixing method and to ascertain the best possible technique that can identify and position of aquaculture farms accurately in and around the Younggwang coastal region of Korea. Various conventional techniques existed to extract such information are spectral enhancement and classification. However, these techniques performed on the Landsat-TM imagery do not seem to yield accurate information about the aquaculture farms, and instead lead to misinterpretation and misclassification. A large discrepancy between the actual and extracted information results from spectral confusion and inadequate spatial resolution of the sensor, which leads to occurrence of mixture pixels or "mixels", which are known to be the source of errors in the classified image. To over come this problem, more recently evolved methods such as step-by-step iterative partial spectral end-member extraction linear spectral unmixing methods are attempted. Large errors in extraction of aquaculture farms information through the conventional classification techniques are significantly minimized with the step-by-step iterative partial spectral end-member extraction approach and the accuracy of classification is further improved with linear spectral unmixing approach. The aquaculture fraction derived from unmxing of TM image data was validated using NDVI values in absence of field data. NDVI and aquaculture fraction are positively correlated (R2 = 0.91), indicating the reliability of the sub-pixel classification
MONITOR SPATIAL AND TEMPORAL PATTERNS OF SUSPENDED SEDIMENTS IN THE EAST CHINA AND YELLOW SEAS USING SEAWIFS DATA
Joo Hyung Ryu,Yu Hwan Ahn,P. Shanmugam
Gayana (Concepción) , 2004,
Abstract: Striking patterns of suspended sediments created by a complex interplay of physical, chemical, biological and geological processes in the East China Sea (ECS) and Yellow Sea (YS) have been investigated using SeaWiFS ocean color imagery. The structure of these patterns can reveal a great deal about the processes underlying their formation. Sea surface temperature (SST) analyzed from the Advanced Very High Resolution Radiometer (AVHRR) thermal infrared data and in-situ were used to elucidate the physical factors responsible for the evolution of such patterns in the inner and outer selves areas, whilst concomitant patterns of suspended sediment were tracked from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color imagery. A careful analysis of these patterns in conjugation with other data gave birth to the definition of the evolution of suspended sediments (SS) into four stages: (1) Infant Stage, (2) Younger Stage, (3) Mature Stage and (4) Old Stage. Each of these stages experiences the different characteristics of waters and numerous physical mechanisms that control pattern formation during the winter monsoon. Vertical and horizontal profiles of suspended sediments appear to be useful in predicting the evolution of these stages, of these, the younger stage is identified as important candidate to represent the intrusion of Yellow Sea Warm Current (YSWC) to the northwest of the Jeju-Island
ATMOSPHERIC CORRECTION OF THE LANDSAT SATELLITE IMAGERY FOR TURBID WATERS
Yu Hwan Ahn,P Shanmugam,Joo Hyung Ryu
Gayana (Concepción) , 2004,
Abstract: This paper describes methods for the correction of the atmospheric effects in the Landsat VIS/NIR imagery in relation to the retrieval of meaningful information about the ocean color, especially from Case-2 waters around Korean peninsula. Three atmospheric correction (AC) methods implemented and examined, using the TOA radiance or reflectance data, are 6S radiative transfer model, spectral shape matching (SSMM) and path-extraction methods. The results show that overall shape and magnitude of radiance or reflectance spectra of the atmospherically corrected Landsat VIS/NIR imagery by SSMM appears to have very good agreement with the in-situ spectra collected for clear and turbid waters, while path-extraction over turbid waters though often reproduces in-situ spectra, but yields significant errors for clear waters due to the invalid assumption of zero values for the black ocean pixels of the Landsat VIS/NIR bands. Because of the standard atmosphere with constant aerosols and models adopted in 6S model, a large error is possible between the retrieved and in-situ spectra. Validation suggests that accurate the retrieval of water-leaving radiance is not feasible with the invalid assumption of classical AC algorithms, but is feasible with SSMM.
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