• 한국응용과학기술학회지
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• 제27권2호
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• pp.129-136
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• 2010

A series of noble poly(amide-imide)s and copoly(amide-imide)s bearing 1,2-bis(4-phenoxy)benzene units were synthesized by the direct polycondensation of 1,2-bis(4-trimellitimidophenoxy)benzene[1,2-PTPB] with a combination of commercially available aromatic diamines and diacids such as m-phenylene diamine, p-phenylene diamine(PPD), isophthalic acid and terephthalic acid(TA) in N-methyl-2-pyrrolidone(NMP) using triphenyl phosphite and pyridine as a condensing agent in the presence of dehydrating agent ($CaCl_2$). The resulting polymers had inherent viscosities in the range of 0.37~0.78 dL/g and most of them were soluble m common organic solvents including NMP, dimethylacetamide, dimethylsulfoxide, dimethylformamide, and m-cresol. Wide-angle X-ray diffractograms revealed that the copoly(amide-imide) derived from PPD with mixed acids of 1,2-BTPB and TA, showed crystalline nature, whereas all of the other polymers were found to be amorphous. The glass transition temperatures of the polymers occurred over the temperature range of $270{\sim}323^{\circ}C$ in their differential scanning calorimetry curves and their 10% weight loss temperature, determined by thermogravimetric analysis in air and nitrogen atmosphere, were in the range $465{\sim}535^{\circ}C$, $500{\sim}550^{\circ}C$, respectively, indicating their good thermal stability.

• 한국미생물·생명공학회지
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• 제22권6호
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• pp.685-691
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• 1994

The biodegradation of aromatic compounds by mixed and monoculture was investigated in an artificial wastewater containing 500 mg/l of benzene(B), phenol(P), and toluene(T) in various combinations. None of three strains utilized P-xylene(X) as a carbon source, but they grew well on p-xylene in mixtures with benzene and toluene. In the mixed culture on mixed substrate, the length of lag phase was different depending on the nature of mixture. Cell growths of Flavobac- terium sp. BEN2 and Acinetobacter sp. GEM63 were inhibited in the presence of a 500 mg/l of phenol. When the mixed culture of three strains was cultured in a bench-scale reactor containing artificial wastewater, each of benzene, phenol, and toluene was not detected at 30 hrs, 50 hrs, and 12 hrs after incubation in the treatment. The removal rates of COD$_{t}$(total COD) and COD$_{s}$,(soluble COD) of upper phase after centrifugation during early 50 hrs were ca. 80% and ca. 93.8%, respectively.

• Environmental Engineering Research
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• 제17권2호
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• pp.89-94
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• 2012

Pyrolysis/gasification technology utilizes an energy conversion technique from various waste resources, such as biomass, solid waste, sewage sludge, and etc. to generating a syngas (synthesis gas). However, one of the major problems for the pyrolysis gasification is the presence of tar in the product gas. The tar produced might cause damages and operating problems on the facility. In this study, a gliding arc plasma reformer was developed to solve the previously acknowledged issues. An experiment was conducted using surrogate benzene and naphthalene, which are generated during the pyrolysis and/or gasification, as the representative tar substance. To identify the characteristics of the influential parameters of tar decomposition, tests were performed on the steam feed amount (steam/carbon ratio), input discharge power (specific energy input, SEI), total feed gas amount and the input tar concentration. In benzene, the optimal operating conditions of the gliding arc plasma 2 in steam to carbon (S/C) ratio, 0.98 $kWh/m^3$ in SEI, 14 L/min in total gas feed rate and 3.6% in benzene concentration. In naphthalene, 2.5 in S/C ratio, 1 $kWh/m^3$ in SEI, 18.4 L/min in total gas feed rate and 1% in naphthalene concentration. The benzene decomposition efficiency was 95%, and the energy efficiency was 120 g/kWh. The naphthalene decomposition efficiency was 79%, and the energy yield was 68 g/kWh.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.959-964
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• 2007

The benzene complexes with dimethyl sulfur (DMS) and fluorinated DMS (FDMS) have been investigated using ab initio calculations. The natural bond orbital (NBO) charge population on S atom varies remarkably for different conformations of DMS and FDMS, which determines the possible binding modes for their benzene complexes. The electronegative substituent at the methyl group of DMS causes a significant change in the molecular electrostatic potential around the sulfur atom and changes the interaction mode with aromatic ring. It was found that the sulfur…π interaction mode does not occur in the DMS-benzene complex, while it does in the FDMS-benzene complex. Both B3LYP and MP2 methods provide reliable structures, while the interaction energy obtained by B3LYP is unreliable.

• Journal of Microbiology
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• 제38권2호
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• pp.53-61
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• 2000

Hydroxybenzoic acids are the most important intermediates in the degradative pathways of various aromatic compounds. Microorganisms catabolize aromatic compounds by converting them to hydroxylated intermediates and then cleave the benzene nucleus with ring dioxygenases. Hydroxylation of the benzene nucleus of an aromatic compound is an essential step for the initiation and subsequent disintegration of the benzene ring. The incorporation of two hydroxyl groups is essential for the labilization of the benzene nucleus. Monohydroxybenzoic acids such as 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, and 4-hydrosybenzoic acid, opr pyrocattechuic acid that are susceptible for subsequent oxygenative cleavage of the benzene ring. These terminal aromatic intermediates are further degraded to cellular components through ortho-and/or meta-cleavage pathways and finally lead to the formation of constituents of the TCA cycle. Many groups of microorganisms have been isolated as degraders of hydroxybenzoic acids with diverse drgradative routes and specific enzymes involved in their metabolic pahtway. Various microorganisms carry out unusual non-oxidative decarboxylation of aromatic acids and convert them to respective phenols which have been documented. Futher, Pseudomonas and Bacillus spp. are the most ubiquitous microorganisms, being the principal components of microflora of most soil and water enviroments.

• 한국환경과학회지
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• 제21권3호
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• pp.305-312
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• 2012

This work is to study the variations of adsorption characteristics of binary vapor according to packing system of double-layer bed by fixed bed experiment. Breakthrough curves of single and binary vapor composed of acetone and benzene on single-layer and double-layer adsorption bed composed of activated carbon (AC) and silica-aluminar (SA) were compared. Adsorptions of binary vapor on double-layer bed were influenced by the differences of surface area between adsorbents as well as the polarity difference between adsorbent and adsorbate. The roll-up phenomenon of acetone vapor was happened by replacement with competing adsorption between acetone vapor and benzene vapor on AC bed, but it was not happened on SA bed because acetone vapor and benzene vapor had less difference in affinity with SA bed. The breakthrough times of acetone vapor and benzene vapor on AC/SA double-layer bed were three times and 1.4 times larger respectively than on SA/AC double-layer bed, the differences of breakthrough times were relatively larger than the equilibrium adsorption capacities according to packing system of double-layer bed.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.186-191
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• 1985

The effect of pressure and temperature on the stabilities of the charge transfer complexes of hexamethyl benzene with iodine in n-hexane has been investigated by UV-spectrophotometric measurements. In this experiment the absorption spectra of mixed solutions of hexamethyl benzene and iodine in n-hexane were measured at 25, 40 and $60^{\circ}C$ under 1,200, 600, 1200 and 1600 bar. The equilibrium constant of the complex formation was increased with pressure while being decreased with temperature raising. Changes of volume, enthalpy, free energy and entropy for the formation of the complexes were obtained from the equilibrium constants. The red shift at higher pressure, the blue shift at higher temperature and the relation between pressure and oscillator strength were discussed by means of thermodynamic functions. In comparison with the results in the previous studies, it can be seen that the pressure dependence of oscillator strength has a extremum behavior in durene as the variation of ${\Delta}H$ or ${\Delta}S$ with the number of methyl groups of polymethyl benzene near atmospheric pressure in the previous study. The shift or deformation of the potential in the ground state and in the excited state of the complexes formed between polymethyl benzene and iodine was considered from the correlation between the differences of the electron transfer energies and the differences of free energies of the complex formation for the pressure variation.

• 한국미생물·생명공학회지
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• 제1권1호
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• pp.51-57
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• 1973

(1) 2,2'-Methylene bis (3,4,6-trichloroacetoxy benzene)을 모체화합물로 하여 Mannich반응에 의해 11종의 새로운 화합물을 합성했다. (2) 합성화합물중 R위치에 (구조식 들어감) 기를 가진 유도체가 효모보다 세균에 대해 비교적 강한 항균력을 나타냈다.

• 한국시뮬레이션학회논문지
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• 제4권1호
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• pp.121-130
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• 1995

This paper deals with modeling and simulation of an industrial benzene-toluene-xylene plant. Because the fractionation unit of benzene-toluene-xylene plant has a narrow range of boiling point and doesn't have any sidecut and side reboiler, we employed boiling point estimation method in the modeling and simulation of the plant. Soave-Redlich-Kwong equation was used in the computation of thermodynamical properties. We solved resulting nonlinear equations by using Newton-Raphson method which is known to show fast convergence. Results of simulation showed good agreement with actual plant operation data.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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• pp.161-164
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• 2015

A short kinetic mechanism for premixed benzene/air flames was developed with a reduction method of Simulation Error Minimization Connectivity Method(SEM-CM). It consisted of 38 species and 336 elementary reactions. Flame speeds were calculated and compared with those from full mechanisms and experiments of other researcher. Those comparisons are in good agreement between the full mechanism and the short mechanism at high pressure condition. In numerical work the running time with the short mechanism was over 10 times faster than one with the full mechanism.