• Journal of the Korean Society for Advanced Composite Structures
• /
• v.2 no.4
• /
• pp.1-10
• /
• 2011

This study investigates the performance of composite (steel-concrete) frame structures through numerical experiments on individual connections. The innovative aspects of this research are in the use of connections between steel beams and concrete-filled tube (CFT)columns that utilize a combination of low-carbon steel and shape memory alloy (SMA) components. In these new connections, the intent is to utilize the recentering provided by super-elastic shape memory alloy tension bars to reduce building damage and residual drift after a major earthquake. The low-carbon steel components provide excellent energy dissipation. The analysis and design of these structures is complicated because the connections cannot be modeled as being simply pins or full fixity ones they are partial restraint (PR). A refined finite element (FE) model with sophisticated three dimensional (3D) solid elements was developed to conduct numerical experiments on PR-CFT joints to obtain the global behavior of the connection. Based on behavioral information obtained from these FE tests, simplified connection models were formulated by using joint elements with spring components. The behavior of entire frames under cyclic loads was conducted and compared with the monotonic behavior obtained from the 3D FE simulations. Good agreement was found between the simple and sophisticated models, verifying the robustness of the approach.

• Clean Technology
• /
• v.26 no.1
• /
• pp.7-12
• /
• 2020

Ti-SBA-15 catalysts doped with lanthanide ions (Ln/Ti-SBA-15) were successfully synthesized using conventional hydrothermal method. In addition, they were characterized by XRD, FT-IR, DRS, BET, and PL. The activity of these materials on the photocatalytic decomposition of methylene blue under ultraviolet light irradiation was also examined. Ti-SBA-15 catalysts doped with various lanthanide ions maintained their mesoporous structure. The pore size and pore volume of Ln/Ti-SBA-15 materials decreased but their surface area increased upon the doping of lanthanide ion. Ln/Ti-SBA-15 materials exhibited the type IV nitrogen isotherm with desorption hysteresis loop type H2, which was characteristic of mesoporous materials. The size of hysteresis increased in the doping of lanthanide ions on Ti-SBA-15 material. There was no absorption in the visible region (> 400 nm) regardless of the doping of lanthanide ions to TiO₂ particles, while the broad bands at 220 nm appeared at the Ln/Ti-SBA-15 samples, indicating the framework incorporation of titanium into SBA-15. 1 mol% Pr/ Ti-SBA-15 catalysts showed the highest photocatalytic activity on the decomposition of methylene blue but the Ti-SBA-15 catalysts doped with Eu, Er, and Nd ions showed lower activity compared to pure Ti-SBA-15 catalyst. The PL peaks appeared at about 410 nm at all catalysts while the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of methylene blue.

• KSBB Journal
• /
• v.16 no.6
• /
• pp.603-608
• /
• 2001

In this study, we studied on the remeval of toluene vapors in a lab-scale biofilter. Biofiltration was performed in a column fed downflow with contaminated air at ambient conditions. The column was packed with mixture of Peat and Calstene(5:3 vol. Ratio), Synthesized media, Bark and Wood chip, which were inoculated with microbial population of selected stains(Pseudomonas. putida, KCCM 11343, ATCC 12633). The microorganisms were immobilized on the bed medium and then biofilm were formed. The biofilter was operated under the conditions of various inlet toluene concentrations for 180 days and treated up to the elimination capacity of maximum 40 g/㎥hr at the inlet load of 30 g/㎥ hr with percentage removals of 20∼90% and gas retention times between 1 and 2 min. The pressure drop was very negligible through the biofilter columps because its value of 0.054 cmH$_2$O/m was much less than others. The effect of operating conditions such as flow rate, inlet toluene concentration and moisture contents on the performance of the biofilter was sequentially investigated in this study.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.1 no.3
• /
• pp.225-232
• /
• 2013

The inorganic insulating material was fabricated with quartzite, ordinary portland cement(OPC), lime, anhydrous gypsum and foaming agent by hydrothermal reaction. The inorganic insulating material was fabricated by using autoclave chamber under high-temperature and high-pressure. The inorganic insulating material is a porous lightweight concrete. Because of its porous structure, properties of inorganic insulating material were light-weight and high-heat insulation property. Properties of fabricated inorganic insulating material were $0.26g/cm^3$ in specific gravity, 0.4MPa in compressive strength and 0.064W/mK in thermal conductivity. In this study, the inorganic insulating material was fabricated and analyzed at different size of quartzite/OPC, various foaming reagent and functional additives to improve the properties. Consequently, polydimethylsiloxane can improve density and thermal conductivity. Especially, polydimethylsiloxane showed excellent improvement in compressive strength.

• Korean journal of applied entomology
• /
• v.4
• /
• pp.47-50
• /
• 1965

Many of the chlorophenol derivatives are widely used as insecticides, herbicides and plant growth regulators. The function and use of these chemicals would be different according to the number of chlorine and their chemical structures. It was reported in this article that 1) Bis(trichlorophenoxy) ethane was synthesized with 2 mol-trichlorophenol and 1 moi-dibromoethane in 2 moi-Sodium hydroxide alcohol solution, and 3) the insecticidal activity of Bis(trichlorophenoxy) ethane was compared with Phenkapton, Tedion V-18, BHC, and DDT, on Citrus red mite, Bombix mori (Silk worm), and Daikon leaf beetle(Phaedon brassicae) 3) The toxicity of Bis(2, 4, 5-trichlorophenoxy) ethane and Bis(2, 4, 5-trichlorophenoxy) ethane was studied on mice. The following results were obtained. 1) Yield of Bis(2, 4, 5-trichlorophenoxy) ethane, $50.06\%$, m.p. $157-159^{\circ}C$, and yield of Bis(2,4, 6-trichlorophenoxy) ethane, $32.60\%$, m.p. $162-163^{\circ}C$. 2) Insecticidal activity of Bis(2, 4, 5-trichlorophenoxy) ethane to Citrus red mite is stronger than that of Tedion V-18, and weaker than that of Phenkapton. 3) Insecticidal activity of Bis(2, 4, 5-trichlorophenoxy) ethane to Bombix mori is weaker than those of BHC and DDT. 4) Insecticidal activity of Bis(2. 4, 5-trichlorophenoxy) ethane to Daikon leaf beetle proved to be ineffective. 5) Five rams of Bis(2, 4, 5-trichlorophenoxy) ethane and Bis(2, 4, 6-trichlorophenoxy) ethane pet kg of body weight respectively were given to mice orally, and none of the mouse was killed by it after a period of 72 hours. Therefore it seems that there is almost no toxicity.

• Applied Chemistry for Engineering
• /
• v.28 no.3
• /
• pp.263-271
• /
• 2017

The application of mass spectrometry to polymer science has rapidly increased since the development of MALDI-TOF MS. This review summarizes current polymer analysis methods using MALDI-TOF MS, which has been extensively applied to analyze the average molecular weight of biopolymers and synthetic polymers. Polymer sequences have also been analyzed to reveal the structures and composition of monomers. In addition, the analysis of unknown end-groups and the determination of polymer concentrations are very important applications. Hyphenated techniques using MALDI-tandem MS have been used for the analysis of fragmentation patterns and end-groups, and also the combination of SEC and MALDI-TOF MS techniques is recommended for the analysis of complex polymers. Moreover, MALDI-TOF MS has been utilized for the observation of polymer degradation. Ion mobility MS, TOF-SIMS, and MALDI-TOF-imaging are also emerging technologies for polymer characterization because of their ability to automatically fractionate and localize polymer samples. The determination of polymer characteristics and their relation to the material properties is one of the most important demands for polymer scientists; the development of software and instrument for higher molecular mass range (> 100 kD) will increase the applications of MALDI-TOF MS for polymer scientists.

• Journal of Life Science
• /
• v.17 no.8 s.88
• /
• pp.1147-1151
• /
• 2007

The human skin is constantly exposed to environmental irritants such as ultraviolet, smoke and chemicals. Free radicals and reactive oxygen species caused by them play critical roles in cellular damage. They not only injure the skin structure but also participate in the immensely complex inflammatory reaction. Anti-wrinkle effects of the Oriental herb extracts(OHE) were evaluated by the determination of anti-oxidation, collagenase inhibition and collagen synthesis in normal human fibroblast. OHE showed antioxidative activity as high as vitamin C, trolox and DL-penicillamine. Also OHE showed promotive effect on collagen synthesis and inhibitory effect on collagenase activity. These results demonstrated that OHE could be useful as an anti-wrinkle cosmetic ingredient.

• Journal of the Korean Chemical Society
• /
• v.41 no.7
• /
• pp.357-361
• /
• 1997

8-Azaxanthine (1), 3-${\beta}$-D-ribofuranosyl-8-azaxanthine (2), 3-${\beta}$-D-ribofuranosyl-8-azaxanthine-5'-monophosphate (3), and 3-${\beta}$-D-ribofuranosyl-8-azaxanthine-5'-(3-pyridinylcarbonyl)monophosphate (4) were synthesized. The in vitro antitumor activities of the synthesized compounds against P388 mouse leukemia, FM3A mammary carcinoma, and U937 human histiocytic lymphoma cells were determined by MTT assay. 2 with unnatural N-3 and C-1' glycoside bond had activity against three tumor cell lines and $IC_{50}$s of these compounds were 0.05, 0.06, and 0.06 ${\mu}mol/mL$ against three tumor cell lines, respectively. But these compounds had no antibacterial activity. $IC_{50}$s against U937 human histiocytic lymphoma cells were verified with the structural modification: $IC_{50}$s of 1, 2, 3, and 4 were 0.33, 0.06, 0.25, and 0.33 ${\mu}mol/mL$, respectively.

• Journal of Plant Biotechnology
• /
• v.41 no.3
• /
• pp.107-115
• /
• 2014

Vegetable oils (triacylglycerols) produced mainly in seeds of plants are used for valuable foods that supply essential fatty acids for humans as well as industrial raw materials and biofuel production. As the demanding for vegetable oils has increased, plant metabolic engineering to produce triacylglycerols in biomass such as leaves has been considered and explored for alternative source of vegetable oils. Leaves are genetically programmed to supply the fixed carbon by photosynthesis to other organs for plant development and growth. Therefore, in order to produce and accumulate triacylglycerols in leaves, one should take account of multiple metabolic pathways such as carbon flux, competition of carbohydrate and fatty acid biosynthesis, and triacylglycerols turnover in leaves. The recent metabolic engineering strategy has showed potential in which the co-expression of three genes WRINKLED1, DGAT1, and OLEOSIN involved in the critical step for increasing the fatty acid synthesis, accumulating triacylglycerols, and protecting triacylglycerols, respectively produced higher amount of vegetable oils in leaves. Developing of genetically engineered plants producing vegetable oil in biomass at non-agricultural lands will be promising to the future success of the field.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.10
• /
• pp.574-580
• /
• 2020

An inorganic binder is eco-friendly because it can be cured at low temperatures and does not emit harmful gases. In addition, related research is progressing rapidly owing to the small defects in the core. On the other hand, inorganic binders based on silicates (SiO₂-Na₂O) have unique absorbent properties. This results in the absorption of moisture from the air and the weakening of the bonding force. In particular, the castings used in cast steel require high-strength properties because of the higher temperatures than aluminum castings. In this study, waxes containing ester groups were selected to improve the absorption of moisture of inorganic binders. The inorganic binder was characterized by X-ray fluorescence and thermogravimetric analysis-differential thermal analysis. The inorganic binder core strength was then evaluated. In the case of an inorganic binder containing wax, the water resistance increased to 216 N/㎠, confirming the up to 55% improvement in strength. Excellent casting characteristics were confirmed through steel castings.