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Search Results: 1 - 10 of 26757 matches for " Chang Ho Seo "
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Perspective Projection Algorithm Enabling Mobile Device’s Indoor Positioning  [PDF]
Seo Woo Han, Yun Jung Lee, Ji Hyeok Yun, Chang Yong Han, Dae Ho Lee, Doug Young Suh
Journal of Computer and Communications (JCC) , 2018, DOI: 10.4236/jcc.2018.61017
Abstract:
In order to improve the user’s satisfaction with the augmented reality (AR) technology and the accuracy of the service, it is important to obtain the exact position of the user. Frequently used techniques for finding outdoors locations is the global positioning system (GPS), which is less accurate indoors. Therefore, an indoor position is measured by comparing the reception level about access point (AP) signal of wireless fidelity (Wi-Fi) or using bluetooth low energy (BLE) tags. However, Wi-Fi and Bluetooth require additional hardware installation. In this paper, the proposed method of estimating the user’s position uses an indoor image and indoor coordinate map without additional hardware installation. The indoor image has several feature points extracted from fixed objects. By matching the feature points with the feature points of the user image, we can obtain the position of the user on the Indoor map by obtaining six or more pixel coordinates from the user image and solving the solution using the perspective projection formula. The experimental results show that the user position can be obtained more accurately in the indoor environment by using only the software without additional hardware installation.
On the Dynamical Analysis in Aftershock Networks  [PDF]
Woon-Hak Baek, Kyungsik Kim, Ki-Ho Chang, Seung-Kyu Seo, Jun-Ho Lee, Dong-In Lee
Open Journal of Earthquake Research (OJER) , 2018, DOI: 10.4236/ojer.2018.71002
Abstract:
We investigate the dynamical behavior of aftershocks in earthquake networks, and the earthquake network calculated from a time series is constructed by contemplating cell resolution and temporal causality. We attempt to connect an earthquake network using relationship between one main earthquake and its aftershocks from seismic data of California. We mainly examine some topological properties of the earthquake such as the degree distribution, the characteristic path length, the clustering coefficient, and the global efficiency. Our result cannot presently determine the universal scaling exponents in statistical quantities, but the topological properties may be inferred to advance and improve by implementing the method and its technique of networks. Particularly, it may be dealt with a network issue of convenience and of importance in the case how large networks construct in time to proceed on earthquake systems.
Applications of Circular Dichroism for Structural Analysis of Gelatin and Antimicrobial Peptides
Ramamourthy Gopal,Jin Soon Park,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13033229
Abstract: Circular dichroism (CD) is a useful technique for monitoring changes in the conformation of antimicrobial peptides or gelatin. In this study, interactions between cationic peptides and gelatin were observed without affecting the triple helical content of the gelatin, which was more strongly affected by anionic surfactant. The peptides did not adopt a secondary structure in the presence of aqueous solution or Tween 80, but a peptide secondary structure formed upon the addition of sodium dodecyl sulfate (SDS). The peptides bound to the phosphate group of lipopolysaccharide (LPS) and displayed an alpha-helical conformation while (KW) 4 adopted a folded conformation. Further, the peptides did not specifically interact with the fungal cell wall components of mannan or laminarin. Tryptophan blue shift assay indicated that these peptides interacted with SDS, LPS, and gelatin but not with Tween 80, mannan, or laminarin. The peptides also displayed antibacterial activity against P. a er uginosa without cytotoxicity against HaCaT cells at MIC, except for HPA3NT3-analog peptide. In this study, we used a CD spectroscopic method to demonstrate the feasibility of peptide characterization in numerous environments. The CD method can thus be used as a screening method of gelatin-peptide interactions for use in wound healing applications.
Antifungal Activity of (KW)n or (RW)n Peptide against Fusarium solani and Fusarium oxysporum
Ramamourthy Gopal,Hyungjong Na,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms131115042
Abstract: The presence of lysine (Lys) or arginine (Arg) and tryptophan (Trp) are important for the antimicrobial effects of cationic peptides. Therefore, we designed and synthesized a series of antimicrobial peptides with various numbers of Lys (or Arg) and Trp repeats [(KW and RW) n-NH 2, where n equals 2, 3, 4, or 5]. Antifungal activities of these peptides increased with chain length. Light microscopy demonstrated that longer peptides ( n = 4, 5) strongly inhibited in vitro growth of Fusarium solani, and Fusarium oxysporum, at 4–32 μM. Furthermore, longer peptides displayed potent fungicidal activities against a variety of agronomical important filamentous fungi, including F. solani and F. oxysporum, at their minimal inhibitory concentrations (MICs) . However, RW series peptides showed slightly higher fungicidal activities than KW peptides against the two strains. Taken together, the results of this study indicate that these short peptides would be good candidates for use as synthetic or transgenic antifungal agents.
Marine Peptides and Their Anti-Infective Activities
Hee Kyoung Kang,Chang Ho Seo,Yoonkyung Park
Marine Drugs , 2015, DOI: 10.3390/md13010618
Abstract: Marine bioresources are a valuable source of bioactive compounds with industrial and nutraceutical potential. Numerous clinical trials evaluating novel chemotherapeutic agents derived from marine sources have revealed novel mechanisms of action. Recently, marine-derived bioactive peptides have attracted attention owing to their numerous beneficial effects. Moreover, several studies have reported that marine peptides exhibit various anti-infective activities, such as antimicrobial, antifungal, antimalarial, antiprotozoal, anti-tuberculosis, and antiviral activities. In the last several decades, studies of marine plants, animals, and microbes have revealed tremendous number of structurally diverse and bioactive secondary metabolites. However, the treatments available for many infectious diseases caused by bacteria, fungi, and viruses are limited. Thus, the identification of novel antimicrobial peptides should be continued, and all possible strategies should be explored. In this review, we will present the structures and anti-infective activity of peptides isolated from marine sources (sponges, algae, bacteria, fungi and fish) from 2006 to the present.
Isolation and Purification of a Novel Deca-Antifungal Peptide from Potato (Solanum tuberosum L. cv. Jopung) Against Candida albicans
Jong-Kook Lee,Ramamourthy Gopal,Chang Ho Seo,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044021
Abstract: In a previous study, an antifungal protein, AFP-J, was purified from tubers of the potato ( Solanum tuberosum cv. L Jopung) and by gel filtration and HPLC. In this study, the functional peptide was characterized by partial acid digestion using HCl and HPLC. We obtained three peaks from the AFP-J, the first and third peaks were not active in the tested fungal strain. However, the second peak, which was named Potide-J, was active (MIC; 6.25 μg/mL) against Candida albicans. The amino acid sequences were analyzed by automated Edman degradation, and the amino acid sequence of Potide-J was determined to be Ala-Val-Cys-Glu-Asn-Asp-Leu-Asn-Cys-Cys. Mass spectrometry showed that its molecular mass was 1083.1 Da. Finally, we confirmed that a disulfide bond was present between Cys 3 and Cys 9 or Cys 10. Using this structure, Potide-J was synthesized via solid-phase methods. In these experiments, only the linear sequence was shown to display strong activity against Candida albicans. These results suggest that Potide-J may be an excellent candidate compound for the development of commercially applicable antibiotic agents.
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.
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.
PG-2, a Potent AMP against Pathogenic Microbial Strains, from Potato (Solanum tuberosum L cv. Gogu Valley) Tubers Not Cytotoxic against Human Cells
Jin-Young Kim,Ramamourthy Gopal,Sang Young Kim,Chang Ho Seo,Hyang Burm Lee,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14024349
Abstract: In an earlier study, we isolated potamin-1 (PT-1), a 5.6-kDa trypsin-chymotrypsin protease inhibitor, from the tubers of a potato strain ( Solanum tuberosum L cv. Gogu Valley). We established that PT-1 strongly inhibits pathogenic microbial strains, but not human bacterial strains, and that its sequence shows 62% homology with a serine protease inhibitor. In the present study, we isolated an antifungal and antibacterial peptide with no cytotoxicity from tubers of the same potato strain. The peptide (peptide-G2, PG-2) was isolated using salt-extraction, ultrafiltration and reverse-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) showed the protein to have a molecular mass of 3228.5 Da, while automated Edman degradation showed the N-terminal sequence of PG-2 to be LVKDNPLDISPKQVQALCTDLVIRCMCCC-. PG-2 exhibited antimicrobial activity against Candida albicans, a human pathogenic yeast strain, and Clavibacter michiganensis subsp. michiganensis, a plant late blight strain. PG-2 also showed antibacterial activity against Staphylococcus aureus, but did not lyse human red blood cells and was thermostable. Overall, these results suggest PG-2 may be a good candidate to serve as a natural antimicrobial agent, agricultural pesticide and/or food additive.
Stable Isolation of Phycocyanin from Spirulina platensis Associated with High-Pressure Extraction Process
Yong Chang Seo,Woo Seok Choi,Jong Ho Park,Jin Oh Park,Kyung-Hwan Jung,Hyeon Yong Lee
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14011778
Abstract: A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%–5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely α-phycocyanin (18.4 kDa) and β-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (α,α-diphenyl-β-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield.
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