• The Journal of Korean Institute for Practical Engineering Education
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• v.2 no.1
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• pp.35-41
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• 2010

An enzyme-catalized reaction is usually characterized by a very large increase in the rate and high specificity. Kinetics of simple enzyme-catalized reactions are often referred to as Michelis-Menten kinetics. A chemical that interferes with an enzyme's activity is called inhibitor. There are two types of enzyme inhibitions (viz. reversible and irreversible). If an inhibitor attaches to the enzyme with weak bonds, such as hydrogen bonds, the inhibition is usually reversible. Many enzyme reactions are also inhibited reversibly by their corresponding products. The rate of substrate disappearance together with the rate of product formation may be written by nonlinear differential equations. In the present study, numerical analyses of simple enzyme kinetics and inhibited enzyme kinetics are reported for the purpose of undergraduate education in engineering.

• Journal of the Korean Society of Tobacco Science
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• v.27 no.2
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• pp.171-177
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• 2005

Coconut based activated carbon and silica-gels were impregnated with 3-aminopropyltri ethoxysilan(APS) and N-(2-aminoethyl)-3-aminopropyl triethoxysilane (AEAPS) in order to investigate the effect of the amine group and the pore size of the supports on the removal of hydrogen cyanide(HCN) and aldehydes in mainstream smoke(MS). The physicochemical properties of the supports were analyzed by using thermal gravity analyzer(TGA), $N_2$ adsorption and desorption isotherms$(BET,\;N_2)$, and SEM-EDS. According to our experimental data, there was no significant difference in the delivery amount of HCN and aldehydes of non-functionalized silica-gels having meso-pores bigger than $20\AA$. In the case of silica-gels functionalized with APS(APS silica-gel), the delivery amounts of hydrogen cyanide(HCN) and aldehydes decreased with the increase of APS concentration. Silica-gel functionalized with AEAPS(AEAPS silica-gel) showed higher removal efficiency than that of APS silica-gels. The delivery amounts of HCN and aldehydes of activated carbon impregnated with APS and AEAPS increased with the increase of the APS and AEAPS concentrations. In accordance with the specific surface area analysis results, APS and AEAPS molecules decreased the specific surface area by blocking the micro-pores of the activated carbon. The volatile organic components removal efficiency by the micro-pores was higher than that of the amine group impregnated into the activated carbon.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.511-515
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• 2007

The yield of oil was rapidly increased at $440^{\circ}C$ compared to $400^{\circ}C$ and $420^{\circ}C$ when the isothermal pyrolysis of waste ship lubricating oil was carried out in tubular type reactor, and pyrolysis was almost finished within 30 min. The yield of gas was decreased depending on the reaction temperature in which that of solid was not much changed. Pyrolysis experiments of waste ship lubricating oil were carried out with used ZSM-5 produced from a petrochemical process. The yield of gas was highly increased in the case of used ZSM-5 and fresh ZSM-5 compared to the case without catalyst. The produced oil and gas were almost constant for fresh ZSM-5 and used ZSM-5 at the same reaction temperature. In the reaction temperature $400{\sim}440^{\circ}C$, the selectivity of $C_5-C_{11}$ was two times higher with fresh ZSM-5 and used ZSM-5 than the case without catalyst.

• Membrane Journal
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• v.26 no.2
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• pp.146-151
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• 2016

Sulfonated poly (arylene ether sulfone) (SPAES) random copolymers have merits such as high proton conductivity, relatively low production cost, and thermochemical resistance when applied as polymer electrolyte membranes for fuel cells. However, it is difficult to directly employ SPAES copolymers into practical fuel cell membrane applications owing to their low chemical stability and dimensional instability under harsh operation conditions. A plausible solution is to impregnate SPAES copolymers into support films (e.g., electrospun polyimide support) with interconnected pore structures and high thermochemical toughness. In this study, a SPAES copolymer with a swivel group, which induces high free volume for fast ion transport, is chosen as ionomers to prepare pore-filling membranes (PFMs). The feasibility of the resulting membranes is evaluated via membrane characterizations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.2
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• pp.99-105
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• 1991

This study was carried out to provide basic data to be necessary for the selection of an energy recovery process based on the characteristics of municipal solid wastes(MSW). The samples were collected at Kangdong-Ku in Seoul and conducted ultimate and proximate analyses. Laboratory scale anaerobic digesters were operated to determine the non biodegradable fractions of the wastes. The results indicated that carbon and hydrogen contents, and lower heating values could be calculated from the volatile contents of MSW by the following equations : C = 0.57 VS, H =0.084 VS, and HL=49.5 VS-(6-0.045VS) W. Nonbiodegradable fractions were respectively 58.9% of volatile matters and 77.7% of MSW. Incineration and refuse derived fuel(RDF) processes appeared to be the most efficient processes in terms of weight reduction and energy recovery, But determining the energy recovery processes, the fluctuations of heating values of MSW throughout a year and available landfill site and secondary pollution should be considered.

• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.98-107
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• 2017

Pd-based membranes have been widely used in hydrogen purification and separation due to their high hydrogen diffusivity and infinite selectivity. However, it has been difficult to fabricate thin and dense Pd-based membranes on a porous stainless steel(PSS) support. In case of a conventional PSS support having the large size of surface pores, it was required to use complex surface treatment and thick Pd coating more than $6{\mu}m$ on the PSS was required in order to form pore free surface. In this study, we could fabricate thin and dense Pd membrane with only $3{\mu}m$ Pd layer on a new PSS support manufactured by metal injection molding(MIM). The PSS support had low surface roughness and mean pore size of $5{\mu}m$. Pd membrane were prepared by advanced Pd sputter deposition on the modified PSS support using fine polishing and YSZ vacuum filling surface treatment. At temperature $400^{\circ}C$ and transmembrane pressure difference of 1 bar, hydrogen flux and selectivity of $H_2/N_2$ were $11.22ml\;cm^{-2}min^{-1}$ and infinity, respectively. Comparing with $6{\mu}m$ Pd membrane, $3{\mu}m$ Pd membrane showed 2.5 times higher hydrogen flux which could be due to the decreased Pd layer thickness from $6{\mu}m$ to $3{\mu}m$ and an increased porosity. It was also found that pressure exponent was changed from 0.5 on $6{\mu}m$ Pd membrane to 0.8 on $3{\mu}m$ Pd membrane.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1063-1072
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• 2000

Kinetic tests on pyrolysis of the mixture of waste automobile lubricating oil and polystyrene were carried out with thermogravimetric technique at the heating rates of 0.5, 1.0, $2.0^{\circ}C/min$ in a stirred batch reactor. The activation energy and the reaction order were determined at conversions of 1 to 100% using differential method. The mixture of waste automobile lubricating oil and polystyrene was pyrolyzed at lower temperature rather than waste automobile lubricating oil and polystyrene. respectively. Also, the thermal decomposition took place in two broad reaction steps. The pyrolyzed oil of mixture represented high selectivity of styrene monomer and dimer like that of polystyrene pyrolyzed products.

• Investigative Magnetic Resonance Imaging
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• v.8 no.2
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• pp.79-85
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• 2004

Purpose : To evaluate the usefulness and reproducibility of $^1H$ MRS in different 1.5 T MR machines with different coils to compare the SNR, scan time and the spectral patterns in different brain regions in normal volunteers. Materials and Methods : Localized $^1H$ MR spectroscopy ($^1H$ MRS) was performed in a total of 10 normal volunteers (age; 20-45 years) with spectral parameters adjusted by the autoprescan routine (PROBE package). In all volunteers, MRS was performed in a three times using conventional MRS (Signa Horizon) with 1 channel coil and upgraded MRS (Echospeed plus with EXCITE) with both 1 channel and 8 channel coil. Using these three different machines and coils, SNRs of the spectra in both phantom and volunteers and (pre)scan time of MRS were compared. Two regions of the human brain (basal ganglia and deep white matter) were examined and relative metabolite ratios (NAA/Cr, Cho/Cr, and mI/Cr ratios) were measured in all volunteers. For all spectra, a STEAM localization sequence with three-pulse CHESS $H_2O$ suppression was used, with the following acquisition parameters: TR=3.0/2.0 sec, TE=30 msec, TM=13.7 msec, SW=2500 Hz, SI=2048 pts, AVG : 64/128, and NEX=2/8 (Signa/Echospeed). Results : The SNR was about over $30\%$ higher in Echospeed machine and time for prescan and scan was almost same in different machines and coils. Reliable spectra were obtained on both MRS systems and there were no significant differences in spectral patterns and relative metabolite ratios in two brain regions (p>0.05). Conclusion : Both conventional and new MRI systems are highly reliable and reproducible for $^1H$ MR spectroscopic examinations in human brains and there are no significant differences in applications for $^1H$ MRS between two different MRI systems.

• Journal of the Korean Chemical Society
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• v.40 no.4
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• pp.243-248
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• 1996

New routes have been developed for the practical syntheses of dl-Muscone(1) employing cyclopentadecanone(2) as the starting material. In this experiment, addition of bromine to cyclopentadecanone in dried E. Ether solution with a trace of $AlCl_3$ as the catalyst were produced 2-bromocyclopentadecanone(3). This process was enhanced formation of regioselective enolate anion at $C_2$ position. 2-Bromocyclopentadecanone was put into $Li_2CO_3$-LiBr-DMF solution at 140∼150$^{\circ}C$, were produced trans- and cis-2-cyclopentadecen-1-one(4) mixture. Other by-products were reduced by control of reaction temperature and time. Trans- and cis-2-cyclopentadecen-1-one(4) mixture was directly put into dried E. Ether solvent and induce to react dropwise with $CH_3MgBr-Cu_2Cl_2$ complex, all of them got into 1,4-addition, dl-Muscone (1) was formed as the result. Conculsion, through three steps procedure from cyclopentadecanone(2) to dl-Muscone(1), the pure dl-Muscone was obtained with the high proportion of 85%, and synthetic cost was able to be much lower than any other conventional methods as there were no chemical separating steps.

• Journal of Convergence for Information Technology
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• v.11 no.9
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• pp.109-114
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• 2021

Cr(VI)-quinoline compound[(C₉H₇NH)₂Cr₂O₇] was synthesized by the reaction between of quinoline and chromium(VI) trioxide, and structure was FT-IR, elemental analysis. The oxidation ability of benzyl alcohol greatly depends upon the dielectric constant of the used organic solvent, where carbon tetrachloride was worst and N,N'-dimethylformamide was best solvent. Noticeably, in N,N'-dimethylformamide solvent, Cr(VI)-quinoline compound oxidized substituted benzyl alcohols. The Hammett reaction constant(ρ)=-0.69(303K). As a resuit, Cr(VI)-quinoline compound was found as efficicent oxidizing agent that converted benzyl alcohol, allyl alcohol, primary alcohol and secondary alcohols to the corresponding aldehydes or ketones. Cr(VI)-quinoline compound was selective oxidizing agent of benzyl alcohol, allyl alcohol and primary alcohol in the presence of secondary alcohol ones.