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Search Results: 1 - 10 of 24 matches for " Youngjune Gwon "
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Multimodal sparse representation learning and applications
Miriam Cha,Youngjune Gwon,H. T. Kung
Computer Science , 2015,
Abstract: Unsupervised methods have proven effective for discriminative tasks in a single-modality scenario. In this paper, we present a multimodal framework for learning sparse representations that can capture semantic correlation between modalities. The framework can model relationships at a higher level by forcing the shared sparse representation. In particular, we propose the use of joint dictionary learning technique for sparse coding and formulate the joint representation for concision, cross-modal representations (in case of a missing modality), and union of the cross-modal representations. Given the accelerated growth of multimodal data posted on the Web such as YouTube, Wikipedia, and Twitter, learning good multimodal features is becoming increasingly important. We show that the shared representations enabled by our framework substantially improve the classification performance under both unimodal and multimodal settings. We further show how deep architectures built on the proposed framework are effective for the case of highly nonlinear correlations between modalities. The effectiveness of our approach is demonstrated experimentally in image denoising, multimedia event detection and retrieval on the TRECVID dataset (audio-video), category classification on the Wikipedia dataset (image-text), and sentiment classification on PhotoTweet (image-text).
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.
Vibration and Dynamic Response Control of Nonuniform Composite Rotating Blades
Sungsoo Na,Liviu Librescu,Sung-Nam Rim,Gwon-Chan Yoon
International Journal of Rotating Machinery , 2006, DOI: 10.1155/ijrm/2006/13807
Abstract: This paper addresses the free vibration, dynamic response, and the active control of composite rotating pretwisted blades modeled as nonuniform thin-walled beams, fixed at the hub at a setting angle, and incorporating piezoelectrically induced damping capabilities. In this sense, a distributed piezoelectric actuator system activated through the application of an out-of-phase electrical current is used to suppress the dynamic response of the rotating beam subjected to a Heaviside pulse. The blade model incorporates nonclassical effects such as transverse shear, secondary warping, and rotary inertias, and includes the centrifugal and Coriolis force fields. A velocity feedback control law relating the piezoelectrically induced bending moment at the beam tip with appropriately selected kinematical response quantities is used, and the beneficial effects of its implementation upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.
Determining the Factors Affecting Retention of Employees in Taiwanese Electronic's Firms - General Vs Repatriated Employees
Adam H. Cave,Wu-Hua Chung,Soon-Gwon Choi
International Journal of Academic Research in Business and Social Sciences , 2013,
Abstract: This study set out to examine the differences leading to turnover intention between two groups, general and repatriated employees. The issue of whether job satisfaction, organizational commitment and attitude of job-hopping can affect Taiwanese IT general employees and repatriates’ intention to leave the organization was analyzed, and helped to explain the potential difference in turnover intention between the two groups of employees. Based on the results, for general employees, payment, nature of work and job-hopping were found to be negatively related to turnover intention. For repatriated employees, organizational commitment was the only factor found to be significantly related to turnover intention. Surprisingly, there was no significant difference in turnover intention between the two groups, which is contrary to most empirical observations that suggest a higher rate of turnover among repatriated employees. However, there exist very strong differences in terms of reasons to leave an organization between these two groups. The findings of this paper strongly suggest that there exists substantially different reasons leading to turnover between the two groups, and that further support programs or initiatives would go a long way in addressing both groups' concerns.
Vibration and Dynamic Response Control of Nonuniform Composite Rotating Blades
Sungsoo Na,Liviu Librescu,Sung-Nam Rim,Gwon-Chan Yoon
International Journal of Rotating Machinery , 2006,
Abstract: This paper addresses the free vibration, dynamic response, and the active control of composite rotating pretwisted blades modeled as nonuniform thin-walled beams, fixed at the hub at a setting angle, and incorporating piezoelectrically induced damping capabilities. In this sense, a distributed piezoelectric actuator system activated through the application of an out-of-phase electrical current is used to suppress the dynamic response of the rotating beam subjected to a Heaviside pulse. The blade model incorporates nonclassical effects such as transverse shear, secondary warping, and rotary inertias, and includes the centrifugal and Coriolis force fields. A velocity feedback control law relating the piezoelectrically induced bending moment at the beam tip with appropriately selected kinematical response quantities is used, and the beneficial effects of its implementation upon the closed loop eigenvibration and dynamic characteristics of the blade are highlighted.
Physics of Solar Neutron Production: Questionable Detection of Neutrons from the 2007 December 31 Flare
Gerald H. Share,Ronald J. Murphy,Allan J. Tylka,Benz Kozlovsky,James M. Ryan,Chul Gwon
Physics , 2010, DOI: 10.1029/2010JA015930
Abstract: Spacecraft observations in the inner heliosphere offer the first opportunity to measure 1-10 MeV solar neutrons. We discuss the physics of low-energy neutron production in solar flares and show that, even at interacting-particle energies of 2 MeV/nucleon, neutrons with energies >10 MeV are produced. On the other hand, a significant fraction of 1-10 MeV neutrons result from interactions of >10 MeV/nucleon ions in typical flare spectra. We calculate the escaping neutron spectra for mono-energetic and power-law particle spectra at the Sun for the location and observation angle of MESSENGER at the time of its reported detection of low-energy neutrons associated with the 2007 December 31 solar flare. We detail concerns about this questionable observation of solar neutrons: 1. the inferred number of accelerated protons at the Sun for this modest M2-class flare was 10X larger than any flare observed to date, 2. the onset and duration of the 'solar' neutron count rate was similar to that of the solar energetic particles (SEPs), and 3. the authors' argument that the SEPs were dominated by electrons and so could not have produced the neutron counts locally in the spacecraft. In contrast we argue that solar energetic protons and alpha particles, through local neutron production and accidental coincidences, were the source of most of the reported 'solar-neutron' counts.
Effect of Repetitive Lysine-Tryptophan Motifs on the Eukaryotic Membrane
Ramamourthy Gopal,Jong Kook Lee,Jun Ho Lee,Young Gwon Kim,Gwang Chae Oh,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14012190
Abstract: In a previous study, we synthesized a series of peptides containing simple sequence repeats, (KW) n–NH 2 ( n = 2,3,4 and 5) and determined their antimicrobial and hemolytic activities, as well as their mechanism of antimicrobial action. However, (KW) 5 showed undesirable cytotoxicity against RBC cells. In order to identify the mechanisms behind the hemolytic and cytotoxic activities of (KW) 5, we measured the ability of these peptides to induce aggregation of liposomes. In addition, their binding and permeation activities were assessed by Trp fluorescence, calcein leakage and circular dichrorism using artificial phospholipids that mimic eukaryotic liposomes, including phosphatidylcholine (PC), PC/sphingomyelin (SM) (2:1, w/ w) and PC/cholesterol (CH) (2:1, w/ w). Experiments confirmed that only (KW) 5 induced aggregation of all liposomes; it formed much larger aggregates with PC:CH (2:1, w/ w) than with PC or PC:SM (2:1, w/ w). Longer peptide (KW) 5, but not (KW) 3 or (KW) 4, strongly bound and partially inserted into PC:CH compared to PC or PC:SM (2:1, w/ w). Calcein release experiments showed that (KW) 5 induced calcein leakage from the eukaryotic membrane. Greater calcein leakage was induced by (KW) 5 from PC:CH than from PC:SM (2:1, w/ w) or PC, whereas (KW) 4 did not induce calcein leakage from any of the liposomes. Circular dichroism measurements indicated that (KW) 5 showed higher conformational transition compared to (KW) 4 due to peptide-liposome interactions. Taken together, our results suggest that (KW) 5 reasonably mediates the aggregation and permeabilization of eukaryotic membranes, which could in turn explain why (KW) 5 displays efficient hemolytic activity.
Remote Gaze Tracking System on a Large Display
Hyeon Chang Lee,Won Oh Lee,Chul Woo Cho,Su Yeong Gwon,Kang Ryoung Park,Heekyung Lee,Jihun Cha
Sensors , 2013, DOI: 10.3390/s131013439
Abstract: We propose a new remote gaze tracking system as an intelligent TV interface. Our research is novel in the following three ways: first, because a user can sit at various positions in front of a large display, the capture volume of the gaze tracking system should be greater, so the proposed system includes two cameras which can be moved simultaneously by panning and tilting mechanisms, a wide view camera (WVC) for detecting eye position and an auto-focusing narrow view camera (NVC) for capturing enlarged eye images. Second, in order to remove the complicated calibration between the WVC and NVC and to enhance the capture speed of the NVC, these two cameras are combined in a parallel structure. Third, the auto-focusing of the NVC is achieved on the basis of both the user’s facial width in the WVC image and a focus score calculated on the eye image of the NVC. Experimental results showed that the proposed system can be operated with a gaze tracking accuracy of ±0.737°~±0.775° and a speed of 5~10 frames/s.
Anti-Microbial, Anti-Biofilm Activities and Cell Selectivity of the NRC-16 Peptide Derived from Witch Flounder, Glyptocephalus cynoglossus
Ramamourthy Gopal,Jun Ho Lee,Young Gwon Kim,Myeong-Sun Kim,Chang Ho Seo,Yoonkyung Park
Marine Drugs , 2013, DOI: 10.3390/md11061836
Abstract: Previous studies had identified novel antimicrobial peptides derived from witch flounder. In this work, we extended the search for the activity of peptide that showed antibacterial activity on clinically isolated bacterial cells and bacterial biofilm. Pseudomonas aeruginosa was obtained from otitis media and cholelithiasis patients, while Staphylococcus aureus was isolated from otitis media patients. We found that synthetic peptide NRC-16 displays antimicrobial activity and is not sensitive to salt during its bactericidal activity. Interestingly, this peptide also led to significant inhibition of biofilm formation at a concentration of 4–16 μM. NRC-16 peptide is able to block biofilm formation at concentrations just above its minimum inhibitory concentration while conventional antibiotics did not inhibit the biofilm formation except ciprofloxacin and piperacillin. It did not cause significant lysis of human RBC, and is not cytotoxic to HaCaT cells and RAW264.7 cells, thereby indicating its selective antimicrobial activity. In addition, the peptide’s binding and permeation activities were assessed by tryptophan fluorescence, calcein leakage and circular dichroism using model mammalian membranes composed of phosphatidylcholine (PC), PC/cholesterol (CH) and PC/sphingomyelin (SM). These experiments confirmed that NRC-16 does not interact with any of the liposomes but the control peptide melittin did. Taken together, we found that NRC-16 has potent antimicrobial and antibiofilm activities with less cytotoxicity, and thus can be considered for treatment of microbial infection in the future.
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.
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