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Search Results: 1 - 10 of 6886 matches for " Kyung-Hwan Jung "
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Punching and Local Damages of Fiber and FRP Reinforced Concrete under Low-Velocity Impact Load  [PDF]
Kyung-Hwan Min
Open Journal of Civil Engineering (OJCE) , 2018, DOI: 10.4236/ojce.2018.81006
Abstract: In recent years, the development and application of high performance fiber reinforced concrete or cementitious composites are increasing due to their high ductility and energy absorption characteristics. However, it is difficult to obtain the required properties of the FRCC by simply adding fiber to the concrete matrix. Many researchers are paying attention to fiber reinforced polymers (FRP) for the reinforcement of construction structures because of their significant advantages over high strain rates. However, the actual FRP products are skill-dependent, and the quality may not be uniform. Therefore, in this study, two-way punching tests were carried out to evaluate the performances of FRP strengthened and steel and polyvinyl alcohol (PVA) fiber reinforced concrete specimens for impact and static loads. The FRP reinforced normal concrete (NC), steel fiber reinforced concrete (SFRC), and PVA FRCC specimens showed twice the amount of enhanced dissipated energy (total energy) under impact loadings than the non-retrofitted specimens. In the low-velocity impact test of the two-way NC specimens strengthened by FRPs, the total dissipated energy increased by 4 to 5 times greater than the plain NC series. For the two-way specimens, the total energy increased by 217% between the non-retrofitted SFRC and NC specimens. The total dissipated energy of the CFRP retrofitted SFRC was twice greater than that of the plain SFRC series. The PVA FRCC specimens showed 4 times greater dissipated energy than for the energy of the plain NC specimens. For the penetration of two-way specimens with fibers, the Hughes formula considering the tensile strength of concrete was a better predictor than other empirical formulae.
Molecular Characterization of Enterotoxigenic Escherichia coli Strains Isolated from Diarrheal Patients in Korea during 2003–2011
Kyung-Hwan Oh, Dong Wook Kim, Su-Mi Jung, Seung-Hak Cho
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096896
Abstract: Enterotoxigenic Escherichia coli (ETEC) is one of the major causes of infectious diarrhea in developing countries. In order to characterize the molecular features of human ETEC isolates from Korea, we investigated the profiles of enterotoxin and colonization factor (CF) genes by polymerase chain reaction (PCR) and performed multilocus sequence typing (MLST) with a total of 291 ETEC strains. The specimens comprised 258 domestic strains isolated from patients who had diarrhea and were from widely separated geographic regions in Korea and 33 inflow strains isolated from travelers visiting other Asian countries. Heat-stable toxin (STh)-possessing ETEC strains were more frequent than heat-labile toxin (LT)-possessing ETEC strains in the domestic isolates, while the detection rates of both enterotoxin genes were similar in the inflow isolates. The profile of CF genes of domestic isolates was similar to that of inflow isolates and the major CF types of the strains were CS3-CS21-CS1/PCF071 and CS2-CS3-CS21. Most of these 2 CF types were detected in ETEC strains that possess both lt and sth genes. The major MLSTST types of domestic isolates were ST171 and ST955. Moreover, the 2 major CF types were usually found concomitantly with the 2 major MLST STs, ST171 and ST955. In conclusion, our genotyping results may provide useful information for guiding the development of geographically specific vaccines against human ETEC isolates.
Autologous chondrocyte implantation for rheumatoid arthritis of the knee: a case report
Seok-Jung Kim, Cheong-Ho Chang, Dong-Sam Suh, Hyun-Kwon Ha, Kyung-Hwan Suhl
Journal of Medical Case Reports , 2009, DOI: 10.1186/1752-1947-3-6619
Abstract: We treated rheumatoid arthritis of the right knee in a 35-year-old female Korean patient using autologous chondrocyte implantation. Twelve months after surgery, the patient could walk without pain.Autologous chondrocyte implantation appears to be effective for treating rheumatoid arthritis of the knee.Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints. To date, pharmacologic treatment remains the primary form of treatment, however, if pain and limitation of joint function become severe and debilitating, surgical treatment should be considered [1]. Over the last few decades, artificial joint replacement techniques have developed very rapidly and many arthritic conditions have thus been successfully treated [2]. However, as total joint arthroplasty is not permanent, in some cases, revisional surgery is inevitable, especially for young patients [3]. Therefore, there is an ever-increasing need for a method that biologically regenerates the arthritic lesion of the knee as patient longevity continually increases. This report presents the case of a 35-year-old woman with a painful, arthritic knee and her treatment using autologous chondrocyte implantation (ACI).A 35-year-old Korean woman with RA was admitted for right knee joint pain. Plain radiographs (Figure 1a) revealed progression of arthritis with lateral joint space narrowing when compared with radiographs obtained 4 years previously. The patient refused total joint replacement arthroplasty which our medical staff recommended and requested ACI. Knee arthroscopy was then performed to harvest 200g of autologous cartilage from the intercondylar notch (Figure 1b,c). The cartilage fragment was sent to a commercial cell culturing facility (SewonCellontech, Seoul) for processing.Autologous chondrocyte implantation was performed 6 weeks after her initial surgery when 48 × 106 chondrocytes had been cultured. Autologous chondrocytes were aseptically processed, suspended in sterile
Treatment of osteonecrosis of the femoral head using autologous cultured osteoblasts: a case report
Seok-Jung Kim, Won-Jong Bahk, Cheong-Ho Chang, Jae-Deog Jang, Kyung-Hwan Suhl
Journal of Medical Case Reports , 2008, DOI: 10.1186/1752-1947-2-58
Abstract: We present the case of a patient with bilateral osteonecrosis of the femoral head treated with autologous cultured osteoblast injection.Although our experience is limited to one patient, autologous cultured osteoblast transplantation appears to be effective for treating the osteonecrosis of femoral head.Osteonecrosis of the femoral head is a progressive disease that leads to femoral head collapse and osteoarthritis [1]. A number of surgical procedures have been developed to preserve the femoral head, however, there is no single treatment method which completely cures this debilitating disease.Bone regeneration by autogenous cell transplantation is one of the most promising treatment concepts currently being developed, as it eliminates the problems of donor site morbidity for autologous grafts, the immunological problems of allogenic grafts, and loosening of implants in total joint arthroplasty.A 31-year old man was admitted with symptoms of acute joint pain of three weeks' duration in both hips. The patient had no specific past history of disease and his laboratory findings were normal. Plain radiographs (Fig. 1A) and MR examination (Fig. 1B) revealed Ficat II osteonecrosis of both femoral heads. The left femoral head was treated by allograft immediately after core decompression, while the right side was treated by injection of autologous cultured osteoblasts for four weeks after the core decompression (Fig. 1C).Follow-up CT obtained one year following treatment, demonstrated that the right femoral head had bone reformation in multiple necrotic areas, that the femoral head was still in optimal condition, and that the left head showed absorption of the grafted bone as well as disease progression.Radiographs obtained five years following surgery showed evidence of remodeling as well as maintenance of the right femoral head, but the left femoral head showed slight irregularity, sclerotic changes, and osteophyte formation (Fig. 1D). On both the MRI (Fig. IE) and the CT
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.
Who makes utilitarian judgments? The influences of emotions on utilitarian judgments
So Young Choe,Kyung-Hwan Min
Judgment and Decision Making , 2011,
Abstract: Recent research has emphasized emotion's role in non-utilitarian judgments, but has not focused much on characteristics of subjects contributing to those judgments. The present article relates utilitarian judgment to individual disposition to experience various emotions. Study 1 first investigated the relationship among state emotions and utilitarian judgment. Diverse emotions were elicited during judgment: guilt, sadness, disgust, empathy, anger, and anxiety, etc. Using psychological scales, Study 2 found that trait emotions predict the extent of utilitarian judgments, especially trait anger, trait disgust, and trait empathy. Unlike previous research that designated emotions only as factors mitigating utilitarian judgment, this research shows that trait anger correlates positively with utilitarian judgment. On the other hand, disgust and empathy correlated negatively. Guilt and shame---though previous research argued that their absence increased utilitarian judgment---appear unrelated to the extent of utilitarian judgment. These results suggest that people's emotional dispositions can affect their judgment. This finding might contribute to untangling the complex mechanisms of utilitarian judgments.
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.
Proximity-induced giant spin-orbit interaction in epitaxial graphene on topological insulator
Kyung-Hwan Jin,Seung-Hoon Jhi
Physics , 2012, DOI: 10.1103/PhysRevB.87.075442
Abstract: Heterostructures of Dirac materials such as graphene and topological insulators provide interesting platforms to explore exotic quantum states of electrons in solids. Here we study the electronic structure of graphene-Sb2Te3 heterostructure using density functional theory and tight-binding methods. We show that the epitaxial graphene on Sb2Te3 turns into quantum spin-Hall phase due to its proximity to the topological insulating Sb2Te3. It is found that the epitaxial graphene develops a giant spin-orbit gap of about ~20 meV, which is about three orders of magnitude larger than that of pristine graphene. We discuss the origin of such enhancement of the spin-orbit interaction and possible outcomes of the spin-Hall phase in graphene.
Tetra-μ-benzoato-bis[(3-methylquinoline)copper(II)](Cu—Cu)
Byeong Kwon Park,Kyung-Hwan Jang,Pan-Gi Kim,Cheal Kim
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808024859
Abstract: In the title compound, [Cu2(C7H5O2)4(C10H9N)2], the paddle-wheel-type dinuclear complex molecule contains four bridging benzoate groups and two terminal 3-methylquinoline ligands. The asymmetric unit contains one and a half molecules with a total of three independent Cu atoms; there is an inversion center at the mid-point of the Cu...Cu bond in one molecule. The octahedral coordination of each Cu atom, with four O atoms in the equatorial plane, is completed by an N atom of a 3-methylquinoline ligand [Cu—N = 2.190 (4)–2.203 (3) ] and by another Cu atom [Cu...Cu = 2.667 (1) and 2.6703 (7) ]. The Cu atoms are all ca 0.22 out of the plane of the four bonded O atoms.
Topological fate of edge states of Bi single bilayer on Bi(111)
Han Woong Yeom,Kyung-Hwan Jin,Seung-Hoon Jhi
Physics , 2015,
Abstract: We address the topological nature of electronic states of step edges of Bi(111) films by first principles band structure calculations. We confirm that the dispersion of step edge states reflects the topological nature of underlying films. This result unambiguously denies recent claims that the step edge state on the surface of a bulk Bi(111) crystal or a sufficiently thick Bi(111) films represents non-trivial edge states of the two dimensional topologcial insulator phase expected for a very thin Bi(111) film. The trivial step edge states have a gigantic spin splitting of one dimensional Rashba bands and the substantial intermixing with electronic states of the bulk, which might be exploited further.
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