• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.3
• /
• pp.307-315
• /
• 2016

The aim of this research is analyzing the fundamental properties and autogenous shrinkage reducing performance of 70 and 100MPa grade high performance concrete including emusified refined cooking oil(ERCO) under the mock-up conditions. As a results of experiment, the mixture contained 0.5% of ERCO showed slightly decreased slump flow while the slump was increased and segregation resistance performance was improved as 2.5 of EIS. For air content, all mixtures satisfied target air content with increased unit weight and delayed setting time with ERCO addition. In the case of compressive strength, when ERCO was added 0.5%, the result of approximately 5 to 10% of increased compressive strength was observed. For the autogenous shrinkage, ERCO contributed on 20-30% of shrinkage reducing performance comparing to Plain mixture without ERCO. It is considered that capillary pore filling action of soap particles occurred by the reaction of ERCO in cement paste between fatty aicd and calcium hydroxide contributed the shrinkage reducing performance. Based on these mock-up test results, application of the high performance concrete mixture with ERCO on CFT actual structure was decided.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.40 no.5
• /
• pp.635-641
• /
• 2011

Anti-atherogenic effects in tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$)-stimulated human umbilical vein endothelial cells (HUVEC) are involved with suppressed oxidative stress, cell adhesion molecules, and pro-inflammatory factors. The aim of this study was to determine whether green tea seed coat ethyl acetate fraction (GTSCE) could modulate cell adhesion molecules and inflammatory mediators in HUVEC stimulated with TNF-${\alpha}$. Nitric oxide (NO) production was significantly increased in TNF-${\alpha}$-stimulated HUVEC compared to TNF-${\alpha}$ only treated cells. The NO that is produced by endothelial nitric oxide synthase dilates blood vessels and has protective effects against platelet and leucocyte adhesion. GTSCE at 25, 50, 75, and $100\;{\mu}g$/mL significantly (p<0.05) reduced TNF-${\alpha}$ production. GTSCE significantly (p<0.05) inhibited soluble vascular cell adhesion molecule-1 level, in a dose-dependent manner. Monocyte chemoattractant protein-1 level was also significantly (p<0.05) inhibited by GTSCE treatment at $75\;{\mu}g$/mL compared to the TNF-${\alpha}$-only treated group. Total antioxidant capacity by GTSCE was significantly (p<0.05) enhanced compared to the TNF-${\alpha}$-only treated group. These results suggest that GTSCE can inhibit the production of cell adhesion molecules and inflammatory mediators and could be used as a candidate bioactive material to prevent the development of atherosclerosis.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.23 no.5
• /
• pp.974-979
• /
• 2009

Proliferation of vascular smooth muscle cell(VSMC) is one of the key features in onset of atherosclerosis and restenosis after vascular surgery such as stent implant. Atherosclerotic plaques are usually composed of collagen, elatsin and smooth muscle cells. Release of matrix metalloproteinases(MMPs) is considered to have correlation with development of atherosclerotic plaques. Based on the hypothesis that MMP inhibition would be helpful in the treatment of atherosclerosis, we investigated inhibition of MMP activity and migration of TNF-$\alpha$-induced human aortic smooth muscle cell(HASMC) by Cinnamomi Ramulus(CC). The result from gelatin zymography showed that CC inhibited MMP-9 activity in a dose-dependent manner. In addition, CC considerably inhibited the migration of HASMC induced by TNF-$\alpha$, while it showed little cytotoxic effect on HASMC. These results suggest that CC can be a potential anti-atherosclerotic agent through inhibition of MMP-9 activity and SMC migration.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.805-808
• /
• 2008

This study analyzed the basic characteristics of concretes to develop 3 ingredients high performance concrete that displaced BS and FA, and the results are as follows. As part of fresh concrete characteristics, the flow was shown more increase than OPC with increase in admixture material displacement rate, and air amount tended to decrease with increase in admixture displacement rate. As hardened concrete characteristics, compressive strength decreased below OPC at early age with increase in BS and FA displacement rate, however at age 28 days, it was similar to OPC or increased above that. Particularly, at B30F15 with age 28 days, its compressive strength was about 15% higher than OPC

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.2
• /
• pp.152-158
• /
• 2022

The purpose of this study is to investigate experimentally the compressive strength and tensile behavior of cement composites reinforced by selvedge short fiber from high performance fabric. Four types of mixtures according to the types of selvedge short fibers were prepared and compressive strength and tension tests were performed. Test results showed that the compressive strength values of composites investigated in this study ranged from 64 MPa to 66 MPa and all composites showed strain-hardening behavior. The tensile strain capacity values of composites ranged from 2.6 % to 2.8 % and multiple cracking behavior was observed in all composites.

• Clinical and Experimental Pediatrics
• /
• v.49 no.4
• /
• pp.368-374
• /
• 2006

Purpose : The prevalence of obesity in children is increasing rapidly. Epidemiologic studies suggest that obesity induced atherosclerosis may start in childhood. We investigated whether obese children show early abnormalities of the arterial wall and endothelial dysfunction. Methods : Thirty-eight obese children(14-16 years old of age, male, body mass index $29.40{\pm}3.18kg/m^2$) and forty-five age and sex-matched healthy control children(body mass index $18.43{\pm}1.01kg/m^2$) were enrolled. Their carotid artery intima-media thickness(IMT) and brachial artery flowmediated dilation(FMD) response were measured by high-quality ultrasound system, and compliance, distensibility, stiffness index, incremental elastic modulus and wall stress were calculated by equation. In addition, we looked at the relations between these arterial features and metabolic cardiovascular risk factors. Results : The obese children had significantly increased IMT($0.52{\pm}0.09mm$ vs $0.40{\pm}0.07mm$, P< 0.001) and markedly impaired FMD($7.35{\pm}7.78$ percent vs $20.34{\pm}16.81$ percent, P<0.001) than the healthy controls. But the compliance and distensibility were lower, and the stiffness index, incremental elastic modules and wall stress were higher in the obese group than the control group, but not statistically significantly. Body mass index was highly associated with increased IMT(r=0.612, P<0.001) and reduced FMD(r=-0.414, P<0.001). Conclusion : We showed the deleterious effect of child obesity on both early functional and structural atherosclerotic markers. The ultrasonic findings will be used for screening and follow up markers to identify high-risk patients among obese children.

• Journal of Technologic Dentistry
• /
• v.19 no.1
• /
• pp.21-35
• /
• 1997

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-20Pd-20Cu ternary alloy and Au addition alloy. These alloys were melted and casted by induction electic furace and centrifugal casting machine in Ar atmoshpere. These specimens were solution treated for 2hr at $800^{\circ}C$ and were then quenched into iced water, and aged at $350{\sim}550^{\circ}C$ Age-hardening characteristics of the small Au-containing Ag-pPd-Cu dental alloys were investigated by means of hardness testing, X-ray diffraction and electron microscope observations, electrical resistance, differential scanning calorimetric, emergy dispersed spectra and electron probe microanalysis. Principal results are as follows : Hardening occured in two stages, I. e., stage I in low temperature and stage II in high temperature regions, during continuous aging. The case of hardening in stage I was due to the formation of the Llo type face centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affedted by the Cu concentration. In stage II, decomposition of the $\alpha$ solid solution to a PdCu ordered phase(L1o type) and an Agrich ${\alpha}2$ phase occurred and a discontiunous precipitation occurred at the grain boundary. Form the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu I type face-centered tetragonal structure. Precipitation procedure was ${\alpha}\to{\alpha}+{\alpha}2+PdCu\to{\alpha}1+{\alpha}2+PdCu$ at Pd/Cu = 1 Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at $450^{\circ}C$.

• Nuclear Medicine and Molecular Imaging
• /
• v.42 no.1
• /
• pp.8-16
• /
• 2008

Purpose: To assess the effect of extracranial-intracranial (EC-IC) bypass surgery on hemodynamic improvement, we evaluated serial regional cerebral hemodynamic change of the middle cerebral artery (MCA) in symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or MCA using $^{99m}Tc$-ECD acetazolamide stress brain perfusion SPECT (Acetazolamide SPECT). Materials and Methods: The patients who had suffered a recent stroke with atherosclerotic ICA or MCA occlusion underwent EC-IC bypass surgery and Acetazolamide SPECT at 1 week before and three to six months after surgery. For image analysis, attenuation corrected images were spatially normalized to SPECT templates with SPM2. Anatomical automated labeling was applied to calculate mean counts of each Volume-Of-Interest (VOI). Seven VOIs of bilateral frontal, parietal, temporal regions of the MCA territory and the ipsilateral cerebellum were defined. Using mean counts of 7 VOIs, cerebral perfusion index and perfusion reserve index were calculated. Results: Seventeen patients (M:F =12:5, mean age $53{\pm}2yr$) were finally included in the analysis. The cerebral blood flow of the parietal region increased at 1 week (p = 0.003) and decreased to the preoperative level at 3-6 months (p = 0.003). The cerebrovascular reserve of the frontal and parietal regions increased significantly at 1 week after surgery (p<0.01) and improved further at 3-6 months. Conclusion: Cerebrovascular reserve of the MCA territory was significantly improved at early postoperative period after EC-IC bypass and kept improved state during long-term follow-up, although cerebral blood flow did not significantly improved. Therefore, cerebrovascular reserve may be a good indicator of postoperative hemodynamic improvement resulted from bypass effect.

• Polymer(Korea)
• /
• v.25 no.4
• /
• pp.558-567
• /
• 2001

The syntheses of thermal latent catalysts have been carried out by modifying the substituent of pyrazinium salts. The thermal latent properties and cure behaviors of difunctional epoxy resin (diglycidylether of bisphenol-A, DGEBA) with 1 wt% of catalyst as an initiator were investigated by dynamic DSC method. As a result, the synthesized catalysts showed the good latent thermal properties in epoxy system. With increasing the basicity of substituted catalyst, the cure temperature and activation energy of epoxy system were increased, whereas the activity was decreased. This was probably due to the fact that the activity and cure behavior were controlled by ring strain and basicity of substituent. Consequently, the catalyst activity modified by methyl group as an electron donor was decreased in increasing of basicity in an initiation step of epoxy cure system. This is due to a decreasing of stabilities of both leaving group of pyrazinium salts and benzyl cation. However, the catalyst activity modified by cyano group as an electron acceptor was increased in increasing the stability of benzyl cation resulting from organic effects and resonance.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.1
• /
• pp.80-87
• /
• 2020

The purpose of this study is to investigate the physical properties and self-healing effects of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS). The EMMs with GGBFS were prepared with various polymer-binder ratios and GGBFS contents, and tested for strengths, adhesion in tension, water permeation and self-healing effects. The conclusions obtained from the test results are summarized as follows. The compressive strength of the EMMs with GGBFS is reduced with increasing polymer-binder ratios because of reduction of the degree of hardening in the EMMs, and is somewhat inferior to that of unmodified mortars. In the flexural and tensile strengths, the flexural strength of the EMMs is almost constant with increasing polymer-binder ratios. However, the tensile strength of the EMMs is gradually increased with increasing polymer-binder ratios. Regardless of the GGBFS contents, the adhesion in tension of the EMMs increases sharply with increasing polymer-binder ratios. The water permeation of the EMMs is remarkably reduced with increasing polymer-binder ratios and GGBFS contents. The self-healing effect of the hardener-free EMMs with GGBFS is improved with increasing water immersion period at a GGBFS content of 20%.