• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.79-86
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• 2010

This study was performed to evaluate the flexural behavior of Hybrid fiber sheet (HFC) and Hybrid fiber bar (HFB) strengthened reinforced concrete (RC) beams. According to test results, Hybrid fiber reinforcement strengthened RC beams showed approximately 60 to 200% higher reinforcing effects than that of un-reinforced specimens. In addition, the reinforced beams showed the ideal failure pattern, which is failed presenting the ductile behavior after yielding of the reinforcing bar. More specifically, in the case of HFB reinforced RC beams, the difference with puttying method was not apparent since HFB beams reinforced using the injection of epoxy and bonding of putty showed the similar failure patterns.

• Tribology and Lubricants
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• v.15 no.1
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• pp.108-115
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• 1999

The electrical and frictional properties of oil-impregnated sintered-metal bearing (OSB) and herringbone-grooved fluid bearing (HFB) with varying loads and speeds were measured. OSB shows very good performance up to 20,000 rpm and 0.05 N, and HFB successfully works up to 35,000 rpm and 0.05 N. From the endurance tests on start-stop and continuous operation, it was confirmed that those bearings could be mass-produced fur use on scanner motor in a laser scanner unit.

• Journal of Nutrition and Health
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• v.34 no.2
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• pp.123-131
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• 2001

The purpose of this study was to investigate the effects of diet composition on serum leptin and lipids profiles in rats. At the baseline, seven 4-week-old Sprague-Dawley rats, male, were sacrificed and the remaining rats were divided into five groups and each group was fed one of the following five dietary regiments for 2 weeks and 6 weeks;the control diet AIN76(CAL, n=2l), high-carbonhydrate(rice)(HCR, n=2l), high-carbohydrate(flour)(HCF, n=2l), high-fat(corn oil)(HFO, n=2l), high-fat(beef tallow)(HFB, n=2l). Serum leptin was determined by a double antibody ELISA assay at the baseline(n=7), 6 week(n=35) and 10 week of age(n=70). At 6 weeks of age, the increase in the Food Efficiency Ratio(FER) was related to adipocyte hyperplasia in rats on HFB diets. The serum triglyceride, total cholesterol, and LDL-cholesterol increased significantly in HFB group, and decreased in HFO group compared to control group. The HFC group showed significant increase in serum triglyceride level compared with control group. After 2 weeks and 6 weeks, noticeably high increases in epididymal adipose tissue fat cell mass and numbers were observed with the HFB fed group. Serum leptin levels increased as body weight increased over the period of time(4weeks; 1.50$\pm$0.13ng/ml versus 10weeks; 2.08$\pm$-.13ng/ml). And this result shows that there are 193% higher in rats fed high fat-beef tallow diet than the control diet. Serum leptin levels of the HFB group(4.01$\pm$0.39mg/ml) were significantly higher than that of the HFO(2.06$\pm$0.5613ng/ml), CAL(2.08$\pm$0.1313ng/ml), HCR(2.41$\pm$0.2113ng/ml) and HCF(2.80$\pm$0.4713ng/ml) at p<0.05. The serum leptin concentration was positively correlated with the amount of epididymal fat pads(r=0.47 p<0.01), serum triglyceride(r=0.49, p<0.001), tatal cholesterol(r=0.48, p<0.001), LDL-cholesterol(r=0.58, p<0.001), atherogenic index(r=0.67, p<0.001), and inversely correlated with HDL-cholesterol(r=-0.65, p<0.001). In conclusion, the changes in composition of dietary fat and carbohydrate intake could affect changes in concentration of serum lipids and leptin. Especially, the high-fat diet with animal fat source could increase circulating leptin level. (Korean J Nutrition 34(2) : 123-131, 2001)

• Clinical and Experimental Reproductive Medicine
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• v.33 no.3
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• pp.171-178
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• 2006

Objective: Human embryonic stem (ES) cells have a great potential in regenerative medicine and tissue engineering. The human ES cells could be differentiated into specific cell types by treatments of growth factors and alterations of gene expressions. However, the efficacy of guided differentiation and isolation of specific cells are still low. In this study, we characterized isolated cells from differentiated human ES cells by magnetic activated cell sorting (MACS) system using specific antibodies to cell surface markers. Methods: The undifferentiated hES cells (Miz-hESC4) were sub-cultured by mechanical isolation of colonies and embryoid bodies were spontaneously differentiated with DMEM containing 10% FBS for 2 weeks. The differentiated cells were isolated to positive and negative cells with MACS system using CD34, human epithelial antigen (HEA) and human fibroblast (HFB) antibodies, respectively. Observation of morphological changes and analysis of marker genes expression were performed during further culture of MACS isolated cells for 4 weeks. Results: Morphology of the CD34 positive cells was firstly round, and then it was changed to small polygonal shape after further culture. The HEA positive cells showed large polygonal, and the HFB positive spindle shape. In RT-PCR analysis of marker genes, the CD34 and HFB positive cells expressed endodermal and mesodermal genes, and HEA positive cells expressed ectodermal genes such as NESTIN and NF68KD. The marker genes expression pattern of CD34 positive cells changed during the extension of culture time. Conclusion: Our results showed the possibility of successful isolation of specific cells by MACS system from undirected differentiated human ES cells. Thus, MACS system and marker antibodies for specific cell types might be useful for guided differentiation and isolation of specific cells from human ES cells.

• Membrane Journal
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• v.18 no.3
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• pp.214-218
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• 2008

Protain affinity membranes based on PES-BSA was preapared by the electrospinning method. The process problem caused by the electrospining was solved by using HFB having high solubility and boiling point. It was expecting that the mass production of protein affinity membrane would be possible with broad range of optimized temperature and humidity. BSA in the PES nanofiber was confirmed by the color change from colorless to violet during the biuret test. The buffer solution with DMSO showed that the amount of elution was 5 times higher than the one when the buffer solution without DMSO was used. This is due to the restriction effect of DMSO on the dissociation of L-tryptophan from BSA during the washing step.

• Membrane Journal
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• v.18 no.4
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• pp.306-316
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• 2008

The adsorption characteristics of L-tryptophan of PES-BSA affinity membranes prepared by using electro-spinning were investigated. It was found that the fiber diameters could be controlled by the comparisons of fiber diameters prepared by various spinning conditions through FESEM and Image Analyzer. Darcy's permeability constants, mechanical properties and hydrophobic properties were enhanced since micro-fibers increased by increasing the composition ratio of HFB and BSA. The elution capacity of L-tryptophan in borate-DMSO buffer solution was higher than that in tris-HCl buffer solution, while the elution capacity of A 7906 type BSA was higher than A 8022 type BSA. This is due to the characteristics of BSA type, i. e. higher purity and uniform molecular weight and better pH stability of A 7906 type BSA than those of A 8022 type BSA.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.719-724
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• 2002

Celgard and Durapore membranes were plasma-treated to enhance the hydrophobicity and durability to amine solution. The plasma gases or vapors used were $CF_4$, Hexafluorobenzene(HFP), Pentafluoropyridine(PFP) and Hexamethyldisiloxane(HMDS). The surface structure of plasma treated membranes was analyzed by FT-IR spectra. The contact angles of plasma treated Celgard and Durapore were dependent of the plasma gases used. $CF_4$ and HMDS plasma increased the contact angles of Celgard and Durapore, while HFB and PFP plasma decreased the contact angles. Durability to monoethanolamine(MEA) solution was enhanced for $CF_4$ plasma-treated Durapore, while the durability was not good for plasma-treated Celgard.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.335-340
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• 2017

Composite resin becomes an essential material in pediatric dentistry. However, incremental filling of composite resin to minimize the polymerization shrinkage takes time. To reduce the polymerization shrinkage, clinicians and researchers have focused on bulk-filling materials. Bulk-base composite resin is newly introduced as bulk-filling composite resin. The purpose of this study was to evaluate microhardness profile of bulk-base composite resin according to the depth of cure. A high flow bulk-base material and a low flow bulk-base material were used for experimental group, and a conventional composite resin was used for control group. Each group consist of 20 specimens, $3.5{\times}3.5{\times}5.0mm$ mold was used to make specimen. Specimens were sectioned at the 2 mm and the 3 mm depth with milling machine. Microhardness profile was measured at the surface, 2 mm depth, 3 mm depth, and 4 mm depth. Microhardness of control group showed statistically significant difference (p < 0.05) according to the polymerization depth. In contrast, experimental group showed no statistically significant difference, except between 0 mm and 4 mm at HFB, 0 mm and 2 mm, 0 mm and 3 mm at MFB. At the surface and the 2 mm depth, the control group showed higher microhardness than the experimental groups (p < 0.05). However, at the 4 mm depth, the experimental groups showed significantly higher microhardness (p < 0.05). The results from this study, the bulk-base composite resin showed higher microhardness at the 4 mm and lower microhardness at the surface and the 2 mm depth. Therefore, if bulk-base resin overcomes the mechanical weakness, it could be considered using in pediatric dentistry.

• Korean Journal of Food Science and Technology
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• v.39 no.4
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• pp.360-365
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• 2007

The studies for the derivatization of 3-monochloropropane-1,2-diol (3-MCPD) were performed mainly as acylation with HFBI (heptafluorobutyrylimidazole), alkylation with PBA (phenylboric acid) and silylation with BSTFA (N,O-bis[trimethylsilyl]trifluoroacetamide). Also silylation with MTBSTFA(N-methyl-N-[tert.-butyldimethylsilyl] trifluoroacetamide) and acylation with MBTFA (N-Methyl-bis[trifluoro-acetamide]) were also considered. Except the TBDMS derivative of 3-MCPD, all the derivatives were detected well. The derivatives of 3-MCPD with HFBI, PBA and BSTFA showed below 10 ${\mu}g/kg$ which was sensitive enough to satisfy Korea maximum residue limit 0.3 mg/kg. Among the tested adsorbents, Extrelut20 and Florisil were evaluated as the proper adsorbents to eliminate the soy sauce matrix for 3-MCPD. Ethyl acetate was the most efficient eluent with good recovery rate. The desired surrogate compound and internal standard were 1,2-butanediol and 1,2-dibromo-3-chloropropane, respectively. The limit of detection for PB-MCPD and TMS-MCPD were 10.16 and 7.06 ${\mu}g/kg$ on GC/MSD, respectively. HFB-MCPD derivative showed the lowest detection limits 2.98 and 5.32 ${\mu}g/kg$ by GC/ECD and GC/MSD, respectively.

• Journal of Life Science
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• v.19 no.2
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• pp.277-283
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• 2009

Biogenic amines are generally formed through the decarboxylation of specific free amino acids by exogenous decarboxylases released by microbial species associated with the fish products and fermented feeds. This study was conducted to investigate the properties of e tuna waste regarding the control of degradation of biogenic amines (histamine, tyramine, tryptamine, putrescine, and cadaverine) that might be related with the anti-nutritional factor of the tuna waste that is used for manufacturing domestic fish meal. The values of pH and the salt content were 6.51, 3.35% in tuna waste and 5.58 and 5.83% in tuna fish meal, respectively. The strains and dominant bacteria tested in the tuna waste sample were 9.20, 9.29, 5.67, 7.82 and 7.58 log CFU/g of total bacteria, aerobic plate count (APC), total coliform (TC), Lactobacillus spp. and Bacillus spp., respectively. The main histamine forming-bacteria (HFB) in tuna waste were detected by silica gel thin-layer chromatography (TLC) and 7 histamine-forming bacterial species were isolated among microbes grown in selective medium. The histamine concentration was determined by detection of fluorescence of ο-phthaldialdehyde (OPA) derivatives using HPLC and the date were used to reconfirm the identities of the amine-producing bacteria. The 15 histamine- forming bacteria strains grown in trypicase soy broth (TSB) supplemented with 1% L-histidine (TSBH) were identified as Lactococcus(L.) lactis subsp. lactis, Klebsiella pneummonlae, L. garvieae 36, Vibrio olivaceus, Hafnia alvei and L. garvieae which were main dominant amine - producing strains, and Morganella morganii identified by 16S ribosomal RNA (rRNA) sequencing with PCR amplification. A Phylogenetic tree generated from the 16S rRNA sequencing data showed different phyletic lines that could be readily classified as biogenic amine forming gram-positive and negative bacteria.