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Search Results: 1 - 10 of 20463 matches for " Hansoo Kim "
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Fe–Al–Mn–C lightweight structural alloys: a review on the microstructures and mechanical properties
Hansoo Kim, Dong-Woo Suh and Nack J Kim
Science and Technology of Advanced Materials , 2013,
Abstract: Adding a large amount of light elements such as aluminum to steels is not a new concept recalling that several Fe–Al–Mn–C alloys were patented in 1950s for replacement of nickel or chromium in corrosion resistance steels. However, the so-called lightweight steels or low-density steels were revisited recently, which is driven by demands from the industry where steel has served as a major structural material. Strengthening without loss of ductility has been a triumph in steel research, but lowering the density of steel by mixing with light elements will be another prospect that may support the competitiveness against emerging alternatives such as magnesium alloys. In this paper, we review recent studies on lightweight steels, emphasizing the concept of alloy design for microstructures and mechanical properties. The influence of alloying elements on the phase constituents, mechanical properties and the change of density is critically reviewed. Deformation mechanisms of various lightweight steels are discussed as well. This paper provides a reason why the success of lightweight steels is strongly dependent on scientific achievements even though alloy development is closely related to industrial applications. Finally, we summarize some of the main directions for future investigations necessary for vitalizing this field of interest.
Photoinduced Membrane Damage of E. coli and S. aureus by the Photosensitizer-Antimicrobial Peptide Conjugate Eosin-(KLAKLAK)2
Gregory A. Johnson, E. Ann Ellis, Hansoo Kim, Nandhini Muthukrishnan, Thomas Snavely, Jean-Philippe Pellois
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091220
Abstract: Background/Objectives Upon irradiation with visible light, the photosensitizer-peptide conjugate eosin-(KLAKLAK)2 kills a broad spectrum of bacteria without damaging human cells. Eosin-(KLAKLAK)2 therefore represents an interesting lead compound for the treatment of local infection by photodynamic bacterial inactivation. The mechanisms of cellular killing by eosin-(KLAKLAK)2, however, remain unclear and this lack of knowledge hampers the development of optimized therapeutic agents. Herein, we investigate the localization of eosin-(KLAKLAK)2 in bacteria prior to light treatment and examine the molecular basis for the photodynamic activity of this conjugate. Methodology/Principal Findings By employing photooxidation of 3,3-diaminobenzidine (DAB), (scanning) transmission electron microscopy ((S)TEM), and energy dispersive X-ray spectroscopy (EDS) methodologies, eosin-(KLAKLAK)2 is visualized at the surface of E. coli and S. aureus prior to photodynamic irradiation. Subsequent irradiation leads to severe membrane damage. Consistent with these observations, eosin-(KLAKLAK)2 binds to liposomes of bacterial lipid composition and causes liposomal leakage upon irradiation. The eosin moiety of the conjugate mediates bacterial killing and lipid bilayer leakage by generating the reactive oxygen species singlet oxygen and superoxide. In contrast, the (KLAKLAK)2 moiety targets the photosensitizer to bacterial lipid bilayers. In addition, while (KLAKLAK)2 does not disrupt intact liposomes, the peptide accelerates the leakage of photo-oxidized liposomes. Conclusions/Significance Together, our results suggest that (KLAKLAK)2 promotes the binding of eosin Y to bacteria cell walls and lipid bilayers. Subsequent light irradiation results in membrane damage from the production of both Type I & II photodynamic products. Membrane damage by oxidation is then further aggravated by the (KLAKLAK)2 moiety and membrane lysis is accelerated by the peptide. These results therefore establish how photosensitizer and peptide act in synergy to achieve bacterial photo-inactivation. Learning how to exploit and optimize this synergy should lead to the development of future bacterial photoinactivation agents that are effective at low concentrations and at low light doses.
Quantitative correlation between promoter methylation and messenger RNA levels of the reduced folate carrier
Rui Yang, Wei-Wei Li, Bang H Hoang, Hansoo Kim, Debabrata Banerjee, Albert Kheradpour, John H Healey, Paul A Meyers, Joseph R Bertino, Richard Gorlick
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-124
Abstract: In the current study, RFC promoter methylation was assessed using methylation specific PCR in a panel of malignant cell lines (n = 8), including MDA-MB-231, and M805, a MTX resistant cell line directly established from the specimen of a patient with malignant fibrohistocytoma, whom received multiple doses of MTX. A quantitative approach of real-time PCR for measuring the extent of RFC promoter methylation was developed, and was validated by direct bisulfite genomic sequencing. RFC mRNA levels were determined by quantitative real-time RT-PCR and were related to the extent of promoter methylation in these cell lines.A partial promoter methylation and RFC mRNA down-regulation were observed in M805. Using the quantitative approach, a reverse correlation (correlation coefficient = -0.59, p < 0.05) was identified between the promoter methylation and RFC mRNA levels in this a panel of malignant cell lines.This study further suggests that promoter methylation is a potential basis for MTX resistance. The quantitative correlation identified in this study implies that promoter methylation is possibly a mechanism involved in the fine regulation of RFC transcription.Methotrexate (MTX) remains an important drug in the treatment of a variety of malignancies, such as acute lymphocytic leukemia (ALL), choriocarcinoma, non-Hodgkin's lymphoma, osteosarcoma, breast cancer, and head and neck cancer. The mechanisms of MTX resistance include: 1) impaired drug transport; 2) reduced drug accumulation because of decreased MTX polyglutamylation or increased drug hydrolysis; 3) increased drug efflux possibly mediated by multiple drug resistance associated proteins (MRPs); 4) alterations in the structure or expression of the target enzyme dihydrofolate reductase (DHFR) and some novel mechanisms proposed recently [1-3]. MTX is delivered into cells predominantly via the reduced folate carrier (RFC), a bi-directional anion exchanger with 12 putative transmembrane domains [4]. To generate sufficien
A genome-wide Asian genetic map and ethnic comparison: The GENDISCAN study
Young Ju, Hansoo Park, Mi Kyeong Lee, Jong-Il Kim, Joohon Sung, Sung-Il Cho, Jeong-Sun Seo
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-554
Abstract: We constructed the genetic map of a Mongolian population in Asia with CRIMAP software. This new map, called the GENDISCAN map, is based on genotype data collected from 1026 individuals of 73 large Mongolian families, and includes 1790 total and 1500 observable meioses. The GENDISCAN map provides sex-averaged and sex-specific genetic positions of 1039 microsatellite markers in Kosambi centimorgans (cM) with physical positions. We also determined 95% confidence intervals of genetic distances of the adjacent marker intervals.Genetic lengths of the whole genome, chromosomes and adjacent marker intervals are compared with those of Rutgers Map v.2, which was constructed based on Caucasian populations (Centre d'Etudes du Polymorphisme Humain (CEPH) and Icelandic families) by mapping methods identical to those of the GENDISCAN map, CRIMAP software and the Kosambi map function. Mongolians showed approximately 1.9 fewer recombinations per meiosis than Caucasians. As a result, genetic lengths of the whole genome and chromosomes of the GENDISCAN map are shorter than those of Rutgers Map v.2. Thirty-eight marker intervals differed significantly between the Mongolian and Caucasian genetic maps.The new GENDISCAN map is applicable to the genetic study of Asian populations. Differences in the genetic distances between the GENDISCAN and Caucasian maps could facilitate elucidation of genomic variations between different ethnic groups.Genetic maps provide specific positions of genetic markers, which are required for performing genetic studies. Linkage analyses, which aim to identify genetic loci related to human phenotypes and complex diseases, have been performed with Caucasian genetic maps even in Asian populations, because no comprehensive Asian genetic maps with dense markers have yet been introduced. Since multipoint methods are frequently used in linkage analyses, it is important to use correct maps for the population being studied [1].Distance between adjacent genetic markers in
hESC Expansion and Stemness Are Independent of Connexin Forty-Three-Mediated Intercellular Communication between hESCs and hASC Feeder Cells
Jin-Su Kim, Daekee Kwon, Seung-Taeh Hwang, Dong Ryul Lee, Sung Han Shim, Hee-Chun Kim, Hansoo Park, Won Kim, Myung-Kwan Han, Soo-Hong Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069175
Abstract: Background Human embryonic stem cells (hESCs) are a promising and powerful source of cells for applications in regenerative medicine, tissue engineering, cell-based therapies, and drug discovery. Many researchers have employed conventional culture techniques using feeder cells to expand hESCs in significant numbers, although feeder-free culture techniques have recently been developed. In regard to stem cell expansion, gap junctional intercellular communication (GJIC) is thought to play an important role in hESC survival and differentiation. Indeed, it has been reported that hESC-hESC communication through connexin 43 (Cx43, one of the major gap junctional proteins) is crucial for the maintenance of hESC stemness during expansion. However, the role of GJIC between hESCs and feeder cells is unclear and has not yet been reported. Methodology/Principal Findings This study therefore examined whether a direct Cx43-mediated interaction between hESCs and human adipose-derived stem cells (hASCs) influences the maintenance of hESC stemness. Over 10 passages, hESCs cultured on a layer of Cx43-downregulated hASC feeder cells showed normal morphology, proliferation (colony growth), and stemness, as assessed by alkaline phosphatase (AP), OCT4 (POU5F1-Human gene Nomenclature Database), SOX2, and NANOG expression. Conclusions/Significance These results demonstrate that Cx43-mediated GJIC between hESCs and hASC feeder cells is not an important factor for the conservation of hESC stemness and expansion.
Current Status of Pyroprocessing Development at KAERI
Hansoo Lee,Geun-IL Park,Jae-Won Lee,Kweon-Ho Kang,Jin-Mok Hur,Jeong-Guk Kim,Seungwoo Paek,In-Tae Kim,IL-Je Cho
Science and Technology of Nuclear Installations , 2013, DOI: 10.1155/2013/343492
Abstract: Pyroprocessing technology has been actively developed at Korea Atomic Energy Research Institute (KAERI) to meet the necessity of addressing spent fuel management issue. This technology has advantages over aqueous process such as less proliferation risk, treatment of spent fuel with relatively high heat and radioactivity, and compact equipments. This paper describes the pyroprocessing technology development at KAERI from head-end process to waste treatment. The unit process with various scales has been tested to produce the design data associated with scale-up. Pyroprocess integrated inactive demonstration facility (PRIDE) was constructed at KAERI and it began test operation in 2012. The purpose of PRIDE is to test the process regarding unit process performance, remote operation of equipments, integration of unit processes, scale-up of process, process monitoring, argon environment system operation, and safeguards-related activities. The test of PRIDE will be promising for further pyroprocessing technology development. 1. Introduction Pyroprocessing treatment can reduced the volume, radioactivity, and heat load of the light water reactor (LWR) spent fuels [1]. In addition, pyroprocessing based on the group recovery of transuranic element (TRU) can provide metal fuels for the sodium-cooled fast reactor while keeping higher intrinsic proliferation resistance. Therefore, successful development of pyroprocessing can save disposal space, reduce the radiotoxicity of spent fuels, and increase uranium utilization efficiency. Korea Atomic Energy Research Institute (KAERI) has been developing pyroprocessing since 1997. The concept development, bench scale testing, and demonstration of laboratory scale key unit process had been carried out since 2006. From 2007 to 2011, the focus moved to the design and construction of engineering-scale integrated system. Pyroprocess integrated inactive demonstration facility (PRIDE) was constructed in 2011 and it began test operation in 2012. Process flow diagram consists of head-end processes (decladding, voloxidation, oxide feed preparation), electrochemical processes (electrolytic reduction, electrorefining, electrowinning), and waste treatment processes as shown in Figure 1. Figure 1: Flow diagram of pyroprocessing (PRIDE at KAERI). 2. Unit Process of Pyroprocessing 2.1. Head-End Process The head-end process in pyroprocessing is to convert spent fuel assembly into a suitable feed material which is supplied to the electrolytic reduction process. The first step of head-end process is to disassemble spent pressurized water
Correlations between Transmembrane 4 L6 Family Member 5 (TM4SF5), CD151, and CD63 in Liver Fibrotic Phenotypes and Hepatic Migration and Invasive Capacities
Minkyung Kang, Jihye Ryu, Doohyung Lee, Mi-Sook Lee, Hye-Jin Kim, Seo Hee Nam, Haeng Eun Song, Jungeun Choi, Gyu-Ho Lee, Tai Young Kim, Hansoo Lee, Sang Jick Kim, Sang-Kyu Ye, Semi Kim, Jung Weon Lee
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102817
Abstract: Transmembrane 4 L6 family member 5 (TM4SF5) is overexpressed during CCl4-mediated murine liver fibrosis and in human hepatocellular carcinomas. The tetraspanins form tetraspanin-enriched microdomains (TEMs) consisting of large membrane protein complexes on the cell surface. Thus, TM4SF5 may be involved in the signal coordination that controls liver malignancy. We investigated the relationship between TM4SF5-positive TEMs with liver fibrosis and tumorigenesis, using normal Chang hepatocytes that lack TM4SF5 expression and chronically TGFβ1-treated Chang cells that express TM4SF5. TM4SF5 expression is positively correlated with tumorigenic CD151 expression, but is negatively correlated with tumor-suppressive CD63 expression in mouse fibrotic and human hepatic carcinoma tissues, indicating cooperative roles of the tetraspanins in liver malignancies. Although CD151 did not control the expression of TM4SF5, TM4SF5 appeared to control the expression levels of CD151 and CD63. TM4SF5 interacted with CD151, and caused the internalization of CD63 from the cell surface into late lysosomal membranes, presumably leading to terminating the tumor-suppressive functions of CD63. TM4SF5 could overcome the tumorigenic effects of CD151, especially cell migration and extracellular matrix (ECM)-degradation. Taken together, TM4SF5 appears to play a role in liver malignancy by controlling the levels of tetraspanins on the cell surface, and could provide a promising therapeutic target for the treatment of liver malignancies.
Design of Quantification Model for Ransom Ware Prevent  [PDF]
Donghyun Kim, Seoksoo Kim
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33C030
Abstract:

The growth of ICT within the society has become increasingly digitized, thus, the overall activity has amounted to various researches for protecting any data from malicious threats. Recently, ransomware has been a rapidly propagated subject for social engineering techniques especially the ransomware. Users can delete a ransomeware code using an antivirus software code. However, the encrypted data would be impossible to recover. Therefore, ransomware must be prevented and must have early detection before it infects any data. In this paper, we are proposing a quantification model to prevent and detect any cryptographic operations in the local drive.

Trends of Noninvasive Radiofrequency and Minimally Invasive Treatment for the Management of Facial Aging  [PDF]
Sunghee Kim, Moonjong Kim
Journal of Cosmetics, Dermatological Sciences and Applications (JCDSA) , 2019, DOI: 10.4236/jcdsa.2019.91003
Abstract: Various treatments for the management of facial aging have been performed among which noninvasive radio-frequency (RF; i.e., thermage) treatment and minimally invasive treatments are on the rise. The purpose of this study was to analyze trends of the treatment of facial aging in Korea and to investigate relationships between the use of noninvasive RF and minimally invasive treatments. A retrospective analysis conducted on data from 4021 patients showed that thermage treatment increased by 134.9% over 5 years. As a person ages, the rate of facial treatment with both the botulinum toxin (for the masseter and lines of the glabella, lateral canthus, and forehead) and the PDO thread lift increases. The use of the treatments, nasolabial fold filler and Silhouette Soft Thread, however, was not associated with aging. The patients receiving thermage treatment were less likely to undergo any of the other treatments including PDO thread lift, Silhouette Soft Thread, nasolabial fold filler, or any of the botulinum toxin treatments. Overall, the results showed that patients who had received noninvasive RF tended to receive less minimally invasive treatment.
The Effect of Prunella on Anti-Inflammatory Activity in RAW264.7 Mouse Macrophage Cells  [PDF]
Meehye Kim
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.39170
Abstract: The extracts of Prunella vulgaris L. (Labiatae), a popular Western and Chinese herbal medicine, was shown to have anti-inflammatory properties, which might be due to partially, their rosmarinic acid content. Inhition of prostaglandine E2 (PGE2) production in lipopolysaccharide (LPS) stimulated RAW264.7 mouse macrophage cells was assessed with an enzyme immunoassay (EIA) following 8-hour treatments with Prunella vulgaris extracts or fractions. Results showed that 95% ethanol extracts from P. vulgaris significantly inhibited PGE2 production. In further studies, fraction 2 from the 95% ethanol extract of P. vulgaris significantly reduced PGE2 production at 66 µg/ml (72% reduction). Cytotoxic-ity did not play a role in the noted reduction of PGE2 seen in either the extracts or fractions from P. vulgaris. High performance liquid chromatography analysis showed that there was 1.4 mM rosmarinic acid in 95% ethanol Prunella extract (201 mg/ml crude extract). Our results suggest that rosmarinic acid may contribute toward the anti-inflammatory activity of Prunella in a dose-response manner. Prunella might have a potential to be used as a functional food for anti-inflammatory activity.
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