• Journal of the Korean Chemical Society
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• v.19 no.1
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• pp.53-64
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• 1975

The polymerization of methyl methacrylate initiated by cobalt(II) chloride in tetrahydrofuran has been studied. The conversion was increased liearly with polymerization time at initial stage of 6${\sim}$7% conversion and then the rate of polymerization was slightly reduced, and after that the autoacceleration was observed. The rate of polymerization was increased with the concentration of cobalt(Ⅱ) chloride, but at the concentration of cobalt(II) chloride higher than $3.4{\times}10^{-4}$ mole/l the rate of polymerization was decreased. The rate of polymerization was dependent on the 1.38 power of the concentration of methyl methacrylate. The effect of the radical inhibitor DPPH was observed and the inhibition time was increased with the concentration of DPPH. The apparent overall activation energy was calculated to be 13.2 kcal/mole. In the copolymerization of methyl methacrylate ($M_1$) and styrene ($M_2$), the monomer reactivity ratio was found to be $r_1$ = 2.35, $r_2$ = 0.78. From the above results. the initiation mechanism of polymerization was discussed and it was considered that the polymerization proceeds mainly via diradical mechaism.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2983-2988
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• 2013

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the reactions of 4-chloro-2-nitrophenyl X-substituted-benzoates (1a-1h) with a series of cyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at $25.0{\pm}0.1^{\circ}C$. The Hammett plot for the reactions of 1a-1h with piperidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ${\rho}_X $ = 1.25 and r = 0.58, indicating that the nonlinear Hammett plot is not due to a change in the rate-determining step (RDS) but is caused by ground-state stabilization through resonance interactions for substrates possessing an electron-withdrawing group in the benzoyl moiety. The Br${\o}$nsted-type plot for the reactions of 4-chloro-2-nitrophenyl benzoate (1d) with a series of cyclic secondary amines curves downward with ${\beta}_2$ = 0.85, ${\beta}_1$ = 0.24, and $pK_a{^o}$ = 10.5, implying that a change in RDS occurs from the $k_2$ step to the $k_1$ process as the $pK_a$ of the conjugate acid of the amine exceeds 10.5. Dissection of $k_N$ into the microscopic rate constants $k_1$ and $k_2/k_{-1}$ ratio associated with the reaction of 1d reveals that $k_2$ is dependent on the amine basicity, which is contrary to generally held views.

• Clean Technology
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• v.2 no.1
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• pp.69-79
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• 1996

Sulfur emission control in coal gasification plants implies the removal of $H_2S$ from the fuel gas in the gas clean-up system. In this study, the effects of particle size of sorbents, temperature of sulfidation and sorbent characteristics on the $H_2S$ removal efficiency of manganese ore were investigated. Experimental results showed that the removal efficiency of $H_2S$ was optimum when the temperature was about $700^{\circ}C$. And that the smaller particle size, the higher the $H_2S$ removal efficiency, but that was not effective very much. As the temperature increases, the reactivity of sorbents has lowered because agglomeration of sorbents increased the intraparticle transport resistance. This phenomenon was confirmed by SEM photographs. The equilibrium ratio ($P_{H_2O}/P_{H_2S}$) obtained by experiments is represented as a ${\log}(P_{H_2O}/P_{H_2S})=5653/T-3.7909$. It was showed that the natural manganese ore could be used as a sorbent because its capacity for $H_2S$ removal is equivalent to the eariler developed sorbents.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.615-626
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• 2016

In the paper, mild solvent soluble alkyl group modified epoxy resins were prepared via a three-step method; (1) the condensation reaction of dodecyl phenol (DP) and formaldehyde, (2) the crosslinking reaction of dodecyl phnol novolac compound (DPC) and bisphenol A diglycidyl ether, (3) the dodecyl phenol novolac epoxy resins containing fatty acid (DPFA) was prepared by introducing fatty acid to DPC. Equivalent ratios of DP and formaldehyde were 1.25~1.333/1.0. Equivalent ratio of DPC and bisphenol A diglycidyl ether (YD-128) was 1.0/2.0. Reactivity, viscosity, molecular weight, solvent solubility, and physical properties of DPFA were investigated. The result show that as the number of aromatic ring of DPFA increased, viscosity increased and solvent solubility improved. When we test the properties of coatings by blending the synthesized DPFA with a white pigment, DPFAC-5 using triphenylphosphine (TPP) as a ring-open catalyst showed optical performance for drying time, adhesion, hardness, impact resistance, acid resistance and storage stability.

• Journal of agricultural medicine and community health
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• v.17 no.1
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• pp.46-55
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• 1992

A systematic study was conducted to identify and isolate a serologically pertinent antigen with high specific activity and low cross reactivity from P.westermani antigen. Differential centrifugation of the homogenate yield three particulate and one soluble fractions ; the $480{\times}G$ pellet(Pw1), the $7650{\times}G$ pellet(Pw2) treated with n-butanol(Pw3), and $100000{\times}G$ supernatnat(Pw4). Comparison of antigenicity of these antigens, based upon differential centrifugation, to that of saline extract of P. westermani worm(SEP) was performed by SDS-PAGE and immunoblot techniques. The results obtained were as follows : 1) The ratio of absorbance value of ELISA against paragonimiasis positive pool sera to that of negative sera was highest when using Pw3 as antigen and that was lowest using Pwl. 2) Silver stained and SDS-PAGE of each antigen showed 34 and 13Kd band as common antigen band, but Pw2 didn't show clear band. 3) By immunoblot 55 and 34Kd bands using SEP and Pw4 showed strong positive reaction without cross reaction with sera from other helmenthic infections. Using Pw3, 10Kd band was observed as specific band. In conclusion, Pw3($100000{\times}G$ pellet urea soluble, treated with n-butanol) and Pw4($100000{\times}G$ supernatant) were usable for ELISA and immunoblot technique.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.15-20
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• 2011

Although CNG is able to meet the current emission standards, it is expected to be impossible to satisfy the requirements of the next EURO-6 emission regulation without an additional after-treatment device. Hydrogen is known to be a gaseous fuel which features the wide flammability limit and the fast reactivity. A certain amount of hydrogen addition to CNG is able to extend the lean combustion range and produce lesser amounts of harmful emissions. In this research, the combustion and emission characteristics of HCNG(mixture of Hydrogen and CNG) fuel were experimented in an 11-liter heavy duty lean burn engine varying hydrogen contents, air-to-fuel ratio and spark timing. The optimization of this HCNG engine for a city bus was performed through the evaluations of oxidation catalyst characteristics.

• Mycobiology
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• v.48 no.4
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• pp.313-320
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• 2020

In Pleurotus sp., green mold, which is considered a major epidemic, is caused by several Trichoderma species. To develop a rapid molecular marker specific for Trichoderma spp. that potentially cause green mold, eleven Trichoderma species were collected from mushroom farms and the Korean Agricultural Culture Collection (KACC). A dominant fungal isolate from a green mold-infected substrate was identified as Trichoderma pleuroticola based on the sequences of its internal transcribed spacer (ITS) and translation elongation factor 1-α (tef1) genes. In artificial inoculation tests, all Trichoderma spp., including T. atroviride, T. cf. virens, T. citrinoviride, T. harzianum, T. koningii, T. longibrachiatum, T. pleurotum, and T. pleuroticola, showed pathogenicity to some extent, and the observed symptoms were soaked mycelia with a red-brown pigment and retarded mycelium regeneration. A molecular marker was developed for the rapid detection of wide range of Trichoderma spp. based on the DNA sequence alignment of the ITS1 and ITS2 regions of Trichoderma spp. The developed primer set detected only Trichoderma spp., and no cross reactivity with edible mushrooms was observed. The detection limits for the PCR assay of T. harzianum (KACC40558), T. pleurotum (KACC44537), and T. pleuroticola (CAF-TP3) were found to be 500, 50, and 5 fg, respectively, and the detection limit for the pathogen-to-host ratio was approximately 1:10,000 (wt/wt).

• Journal of Conservation Science
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• v.11 no.1 s.14
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• pp.28-37
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• 2002

The cleaning in conservation treatment of cultural heritage is very important process. For the best conservation treatment of cultural heritage, except having a good detergency, the cleaning agent must be able to keep the heritage from the secondary deposition and re-soiling, damage and etc. In this paper, the dust (lichen, algae, dust, etc.) on the surface of stone made heritage was treated with some kinds of solvents and analyzed with FT-IR to develop a cleaning agent for stone made cultural heritage. And the cleaning ability to the dust and the corrosion ratio to the granite of the cleaning agent was investigated. Nonionic surfactants were good for treatment of stone-made cultural heritage. The reason is that nonionic surfactants are stable in acidic solution, and possess low reactivity with the compound of stone and low possibility to the second contamination, and build up the reactivities of acids and oxidants. A new cleaning agent composed with $H_2O_2/HF/NP-10$ shows a good cleaning ability for the conservation treatment of stone made cultural heritage.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.332-337
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• 2008

Hydrosilylation reaction of 1,1,1,3,5,5,5-heptamethyl trisiloxane (HMTS) and unsaturated poly(oxyethylene) (UPOE) was carried out in the presence of Speier's catalyst. The effect of molar ratio of two reagents on the reactivity and the structure of the product (HMTS-POE) were investigated by FT-IR and $^1H-NMR$. The pure HMTS-POE without containing unreacted HMTS or UPOE could be obtained by the reaction with excess amount of HMTS and followed by removing unreacted HMTS under vacuum. Under the same reaction conditions, various HMTS-POEs composed of UPOEs with a different molecular weight were synthesized, and the surface tensions of HMTS-POEs were analyzed. HMTS-POE, whose EO contents are in the range of 49~57%, exhibited lower surface tension and a potential application for low molecular weight silicone modified with polyethers.

• Korean Journal of Food Science and Technology
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• v.46 no.5
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• pp.538-543
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• 2014

A sandwich enzyme-linked immunosorbent assay method (sELISA) for detecting the presence of shrimp in processed foods was developed using rabbit polyclonal antibodies against tropomyosin produced by black tiger prawns (shrimp). Based on the standard curve derived using this method, the detection range of shrimp was determined to be $1-100{\mu}g/mL$. The cross-reactivity of these antibodies toward black tiger prawns, fleshy prawns, cocktail prawns, lobster, and blue crab was 100, 73, 155, 18, and 0%, respectively. When shrimp was heated for 10 min, the mean assay recovery of tropomyosin was 121-221% at $70-100^{\circ}C$ and 7.8% at $121^{\circ}C$. When shrimp was added to cream soup, weaning food, sausage, fish paste, and sauce, the mean assay recovery was 397, 639, 168, 234, and 0%, respectively. In sample tests involving 14 commercial items, the coincidence ratio of assay results and reference was 79%.