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Search Results: 1 - 10 of 35366 matches for " Sung-Woo Cho;Joon-Ho Lee "
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Effect of Threshold Value on the Performance of Natural Frequency-Based Radar Target Recognition
Sung-Woo Cho;Joon-Ho Lee
PIER , 2013, DOI: 10.2528/PIER12103104
Abstract: In this paper, the performance analysis of the natural frequency-based radar target recognition in the time domain is considered. We investigate the dependence of the probability of correct classification on a specific threshold value, and determine the optimum threshold value for two targets, and the sub-optimal threshold for multiple targets to maximize the probability of correct classification. Based on the probability density function (PDF) of some quantity consisting of the projections of the late time response onto the column spaces of the matrices constructed using the natural frequencies of the specific targets, we propose how to determine an optimum threshold in the sense that the probability of correct classification of two targets is maximized. By extending the scheme for two targets, we show how to determine a threshold value close to the optimal threshold for multiple targets. The scheme is validated by comparing the performance using the analytic method with that using the Monte-Carlo simulation.
Efficient Implementation of the Capon Beamforming Using the Levenberg-Marquardt Scheme for Two Dimensional Aoa Estimation
Sung-Woo Cho;Joon-Ho Lee
PIER , 2013, DOI: 10.2528/PIER12122711
Abstract: In this paper, we adopt the Levenberg-Marquardt (LM) algorithm to implement the nonlinear multivariable optimization for azimuth/elevation angle-of-arrival (AOA) estimation based on the Capon beamforming algorithm. The formulation is based on the fact that the cost function of the Capon algorithm can be expressed in a least-squares form. The performance in terms of the root mean square error (RMSE) and the computational complexity is illustrated via numerical results.
Performance Analysis of Radar Target Recognition Using Natural Frequency: Frequency Domain Approach
Joon-Ho Lee;Sung-Woo Cho;Sang-Hong Park;Kyung-Tae Kim
PIER , 2012, DOI: 10.2528/PIER12071107
Abstract: We consider the performance analysis of natural frequency-based radar target recognition in the frequency domain. Based on the probability density function (PDF) of some quantity consisting of the projections of the frequency response onto the column spaces of the matrices constructed using the natural frequencies of the specific targets, we propose to analytically calculate the probability of the correct classification, where the PDF is obtained from the inverse Fourier transform of the characteristic function. The scheme is validated by comparing the performance using the analytic method with that using the Monte-Carlo simulation.
Application of the Newton Method to Improve the Accuracy of Toa Estimation with the Beamforming Algorithm and the Music Algorithm
Joon-Ho Lee;Yeong-Seok Jeong;Sung-Woo Cho;Woon-Young Yeo;Kristofer S. J. Pister
PIER , 2011, DOI: 10.2528/PIER10112608
Abstract: In this paper, a numerical method for improving the performance of the beamforming algorithm and the MUSIC algorithm for TOA (Time-of-Arrival) estimation is presented. It has been shown that the conventional beamforming algorithm and the MUSIC algorithm can be used for time delay estimation. Using the beamforming algorithm and the MUSIC algorithm for TOA estimation, the initial estimate for the TOA is obtained. To improve the accuracy of the TOA estimation, we apply the Newton iteration to the initial estimate. The initial estimates obtained from the beamforming algorithm and the MUSIC algorithm are updated to obtain the final estimates which are more accurate than the initial estimates in terms of the RMSE (Root Mean Square Error). To find the TOA which maximizes the beamforming spectrum or the MUSIC spectrum, we find the TOA at which the derivative of the beamforming spectrum with respect to the delay is zero. To find numerically the TOA at which the derivative of the beamforming spectrum or the MUSIC spectrum is zero, the Newton iteration is adopted. In numerical results, the validity of the proposed scheme is illustrated using various examples.
Analysis of Radiological Terrorism on Metropolitan Area
Hosik Yoo,Jeong-ho Lee,Sung-woo Kwak
Energy and Environment Research , 2011, DOI: 10.5539/eer.v1n1p24
Abstract: Possible terrorist attacks on metropolitan areas using radioactive materials have become the subject of lengthy research. This paper discusses an analysis that was conducted through a series of processes: selection of target areas, radioactive materials that may be used, scenario generation, analysis of risk by experts, and radiological consequences. A total of 336 different cases for evaluation were prepared using qualitative judgments; and a risk analysis was conducted to predict the consequence of a successful attack. A HOTSPOT code (which is widely used for initial assessments for emergency response planning) was adopted to evaluate radiological consequences from developed scenarios. We selected the target areas based on data such as: population, number of places where radioactive materials are stored and used, and quantity of radioactive materials. Seven different kinds of radioactive material and two kinds of explosives were considered in building the database. The results suggest that the dispersion distance from an explosion of radioactive material is dependent upon wind currents and the types of detrimental radioactive material utilized. Information from the database established by using radiological scenarios discussed in this study would be useful for countering a radiological attack at the early stag--from the perspective of physical protection.
Positive Association between Aspirin-Intolerant Asthma and Genetic Polymorphisms of FSIP1: a Case-Case Study
Jason Kim, Jeong Hyun Kim, Tae Joon Park, Joon Seol Bae, Jin Sol Lee, Charisse Pasaje, Byung Lae Park, Hyun Sub Cheong, Jong-Sook Park, Sung-Woo Park, Soo-Taek Uh, Mi-Kyeong Kim, Inseon S Choi, Sang Heon Cho, Byoung Whui Choi, Choon-Sik Park, Hyoung Doo Shin
BMC Pulmonary Medicine , 2010, DOI: 10.1186/1471-2466-10-34
Abstract: Aim of this study is to find out whether FSIP1 polymorphisms affect the onset of AIA in Korean population, since it is known that AIA is genetically affected by various genes.We conducted association study between 66 single nucleotide polymorphisms (SNPs) of the FSIP1 gene and AIA in total of 592 Korean subjects including 163 AIA and 429 aspirin-tolerant asthma (ATA) patients. Associations between polymorphisms of FSIP1 and AIA were analyzed with sex, smoking status, atopy, and body mass index (BMI) as covariates.Initially, 18 SNPs and 4 haplotypes showed associations with AIA. However, after correcting the data for multiple testing, only one SNP showed an association with AIA (corrected P-value = 0.03, OR = 1.63, 95% CI = 1.23-2.16), showing increased susceptibility to AIA compared with that of ATA cases. Our findings suggest that FSIP1 gene might be a susceptibility gene for aspirin intolerance in asthmatics.Although our findings did not suggest that SNPs of FSIP1 had an effect on the reversibility of lung function abnormalities in AIA patients, they did show significant evidence of association between the variants in FSIP1 and AIA occurrence among asthmatics in a Korean population.Asthma is a disease that affects a large number of people globally, which is estimated to be about 300 million worldwide [1] and about 3 million asthma patients in South Korea. The disease is defined by the lung inflammation and difficulty of breathing when the suspect is under the influence of various factors that trigger the asthma reaction. Among these factors, non-steroidal anti-inflammatory drugs such as aspirin are known to cause aspirin-intolerant asthma. The AIA was first described in 1922 [2,3], and its most noticeable symptoms include aspirin sensitivity, bronchial asthma, and chronic rhinosinusitis with nasal polyposis [4-6]. When non-steroidal anti-inflammatory drugs such as aspirin are ingested, the drugs cause bronchoconstriction in the patients. Aspirin, also known as ace
Roles of cysteine residues in the inhibition of human glutamate dehydrogenase by palmitoyl-CoA
Sung-Woo Cho
BMB Reports , 2012,
Abstract: Human glutamate dehydrogenase isozymes (hGDH1 andhGDH2) have been known to be inhibited by palmitoyl-CoAwith a high affinity. In this study, we have performed the cassettemutagenesis at six different Cys residues (Cys59, Cys93,Cys119, Cys201, Cys274, and Cys323) to identify palmitoyl-CoA binding sites within hGDH2. Four cysteine residuesat positions of C59, C93, C201, or C274 may be involved, atleast in part, in the inhibition of hGDH2 by palmitoyl-CoA.There was a biphasic relationship, depending on the levels ofpalmitoyl-CoA, between the binding of palmitoyl-CoA and theloss of enzyme activity during the inactivation process. The inhibitionof hGDH2 by palmitoyl-CoA was not affected by theallosteric inhibitor GTP. Multiple mutagenesis studies on thehGDH2 are in progress to identify the amino acid residuesfully responsible for the inhibition by palmitoyl-CoA.
Development operators on 4D moving object databases
JUN Sung-woo,LEE Yang-koo,KIM Sang-ho,CHI Jeong-hee,RYU Keun-ho
重庆邮电大学学报(自然科学版) , 2004,
Clinician awareness of tetanus-diphtheria vaccination in trauma patients: a questionnaire study
Young-Hoon Yoon, Sung-Woo Moon, Sung-Hyuk Choi, Young-Duck Cho, Jung-Youn Kim, Young-Ho Kwak
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2012, DOI: 10.1186/1757-7241-20-35
Abstract: Questionnaires were sent to the directors of the emergency departments of resident training hospitals certified by the Korean Society of Emergency Medicine.Two thirds of the emergency department directors surveyed reported applying tetanus prophylaxis guidelines to more than 80% of wounded patients. However, about 45% of clinicians in the emergency departments considered giving less than half of the wounded patient tetanus booster vaccinations, and there were no distinct differences in tetanus booster vaccination rates among different age groups. Most emergency physicians are familiar with tetanus prophylaxis guidelines for wound management. However, more than half of the emergency department directors reported that the major reason for not considering tetanus-diphtheria vaccination was due to assumptions that patients already had tetanus immunity.Attitude changes should be encouraged among emergency physicians regarding tetanus prophylaxis. As emergency physicians are frequently confronted with patients that are at a high risk for tetanus infection in emergency situations, they need to be more informed regarding tetanus immunity epidemiology and encouraged to administer tetanus booster vaccines.
Inhibition of glutamate dehydrogenase and insulin secretion by KHG26377 does not involve ADP-ribosylation by SIRT4 or deacetylation by SIRT3
Eun-A Kim1,#, Seung-Ju Yang2,#, Soo Young Choi3, Woo Je Lee4,* & Sung-Woo Cho1,*
BMB Reports , 2012,
Abstract: We investigated the mechanisms involved in KHG26377 regulationof glutamate dehydrogenase (GDH) activity, focusing onthe roles of SIRT4 and SIRT3. Intraperitoneal injection of micewith KHG26377 reduced GDH activity with concomitant repressionof glucose-induced insulin secretion. Consistent withtheir known functions, SIRT4 ribosylated GDH and reduced itsactivity, and SIRT3 deacetylated GDH, increasing its activity.However, KHG26377 did not affect SIRT4-mediated ADP-ribosylation/inhibition or SIRT3-mediated deacetylation/activationof GDH. KHG26377 had no effect on SIRT4 protein levels,and did not alter total GDH, acetylated GDH, or SIRT3 proteinlevels in pancreatic mitochondrial lysates. These results suggestthat the mechanism by which KHG26377 inhibits GDHactivity and insulin secretion does not involve ADP-ribosylationof GDH by SIRT4 or deacetylation of GDH by SIRT3.
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