• The Korean Journal of Ceramics
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• 제5권3호
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• pp.296-302
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• 1999

The state of the art of the 2-stage swirl calciner is to make 2-stage counter gas flow in a calciner with cooler hot air. Gas flow in the calciner increases retention time of raw mix particles. Simple structure of the 2-stage swirl calciner operated optimally the rotary cement kiln. In this study, in order to decide the entrance type of the cooler air of the optimal calciner model, an entrance cooler air velocity, the input points of raw mix were analyzed in many aspects with cold model experiment and computational fluidized dynamic simulation. It was found that the entrance type of cooler air fully splite 2-stage for the optimal condition of the cold model calciner. The operation conditions were that the input feeding, the cooler air velocity and the air velocity of throat were 0.33kg/$\textrm m$3$, 15m/s and 20m/s respectively. The performance of 150 t/d the pilot plant connected with the kiln rising duct was that volume capacity of the calciner is over 430 kg/$\textrm m$3$-h, decarbonation rate of raw mix apparently 90%, heat consumption 950 kcal/kg-cli and retention time of raw mix 2.4 sec. Its the best operating condition is cooler air velocity 18m/s, the gas velocity of throat 25m/s, feeding rate of raw mix 10t/h. The operating experience of the pilot plant confirmed the success of scale up for over 3000 t-cli/d.

• 한국식품과학회지
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• 제28권6호
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• pp.1177-1179
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• 1996

식품포장재에 함유되어있는 톨루엔 및 잔류용제를 용출분석하는 방법으로 headspace gas chromatography (static headspace method)를 이용하였다. 5종(methanol, isopropyl alcohol, ethyl acetate, methyl ethyl ketone, toluene)의 표준용제에 대한 머무름시간과 상대표준편차를 검토해 본 결과, 이상적인 머무름시간의 상대표준편차라 할 수 있는 0.15% 이하로 양호하였으며 재현성도 우수하였다. 인쇄된 포장재를 분석한 결과. 주로 methanol, toluene, methyl ethyl ketone이 검출되었고, methanol은 불검출${\sim}0.939\;mg/m^2$, toluene은 불검출${\sim}1.403{\;}mg/m^2$, methyl ethyl ketone은 불검출${\sim}0.932\;mg/m^2$ 함유 되어있는 것으로 나타났으며, 총 잔류 용제는 불검출${\sim}2.433{\;}mg/m^2$ 함유되어 있는 것으로 나타났다.

• 한국환경과학회지
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• 제15권3호
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• pp.211-219
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• 2006

An experimental study on the removal of VOCs gas using a biomembrane reactor were carried out at various inlet gas concentration, specific loading rate, retention time and gas flow rate of volume. The variations of efficiency and various parameters, which are relevant to gas removal, with mixing of soluble gas and without have been discussed. More than 95% of the toluene and methanol present in the feed was successfully removed in each study. The elimination of methanol with mixture of soluble compound of about 300 mg/h corresponds to a portion of 21% if there is a feed stream of 1400 mg/h. On the contrary the maximum efficiency of about 72% of toluene was reached. This is to be rated as a treatment of sorption that the limiting factor of the dismantling speed could be represented by this difficult degradable component. Nevertheless the elimination capacities for this reactor for toluene were on a very high level. For substances which show a very high solubility in silicon rubber an advantage of a bio membrane is clearly shown. Therefore a similarly good result is expected for n-hexane, because of its relatively good permeability which was distinguished during permeation experiments.

• 한국농공학회지
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• 제32권3호
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• pp.102-115
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• 1990

Importance of anaerobic digestion as an energy generating device has been increased as fuel shortage becomes serieous. Several modification methods on the conventional digesters including Powdered Activated Carbon (PAC) addition and two-phase digestion were studied to enhance the gas production. This study investigated the effects of PAC on anaerobic digestion of chicken manure in terms of gas production and sludge stabilization. As a first experiment, an optimum PAC dose for efficient gas production was determined in a batch test. In semi-continuous experiments, an optimum Sludge Retention Time (SRT) at that PAC concentration and an overall substate utilization rate coefficient were investigated. A portion of gas increased by PAC addition was estimated using a substrate utilization rate coefficient of microorganisms attached on PAC. This test was performed in batch experiments using acetic acid as a substrate. The digesters for all experiments were kept 35${\pm}$ 1˚C in a heated water bath. Mixing was performed manually once a day and the produced gas was collected for daily reading. The following conclusions were made for this study. 1. Cptimum PAC concentration was 5% total solids, where gas production rate was increased by 20 percents. 2. Optimum SRT was 7.5 days. 3. Substrate utilization rate coefficient of microorganisms attached on PAC was about twice as much as that of suspended ones.

• 한국환경보건학회지
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• 제24권1호
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• pp.1-8
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• 1998

This study was carried to investigate the treatment characteristics of the phenol and catechol with an anaerobic fluidized bed reactor(AFBR) having a dimension of 9 cm i.d. and 1.25 m height. The reactor was operated at $35\pm 1\circ$C. The COD concentration of the effluent, the gas production rate and the composition of gas were measured to determine the performance of the AFBR as the hydraulic retention time(HRT) was decreased from 2 days to i day at 600 mg/l of the phenol and catechol concentration. Stable treatment of the phenol wastewater could be achieved with the AFBR at 18 days but the catechol wastewater couldn't be. At HRT 2 days, the phenol wastewater showed the COD reduction efficiency of 93% and the gas production of 2.7 l/day and the catechol wastewater was obtained the COD reduction efficiency of 82% and the gas production of 0.72 l/day. Also at HRT 1 day the phenol and catechol wastewater showed the COD reduction efficiency of 95% and 73% and the gas production of 4.0 l/day and 1.25 l/day, respectively.

• 한국환경보건학회지
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• 제25권3호
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• pp.29-35
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• 1999

Quantity and composition of biogas from semi-continuous anaerobic digestion of straw were obtained experimentally in laboratory scale digesters fed with 1 liter of 5% straw-water mixture and maintained at 35$^{\circ}C$. Experiments were carried out for hydraulic retention time(HRT) of 8, 10 and 15days, respectively. The amount and composition of biogas produced were measured until steady-state was achieved for each run. The amount of biogas and methane percent go through a maximum and decrease continuously towards the steady-state after three times operation of hydraulic retention time(HRT). Methane gas production rates at steady-state increase with the increasing of HRT. Biogas production of 0.45 liter/day with 25% methane, 0.42 liter/day with 33.7% methane and 0.492 liter/day with 31.7% methane were obtained for 8, 10 and 15days of HRT, respectively. The high proportion of soluble carbohydrates present in straw makes the volatile fatty acids to build up within the digester causing a drop in pH that inhibits digestion. Regular control of pH is therefore necessary by adding alkalinity. Reductions in COD increase with increase in HRT. The stratification of plant material within the digester is different from that of manure, and modifications in design and operation of digesters may be necessary if they are fed with plant matter.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권1호
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• pp.13-17
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• 2017

Over 30% of domestic soil contamination has occurred via petroleum products and complex oil. Moreover, contamination by complex oil is more intense than it is by a single petroleum product species. In this study, we analyzed sectional TPH (total petroleum hydrocarbon) pattern and sectional ratio of current domestically distributed petroleum products, such as kerosene, diesel, bunker C, and lubricant and complex oils, to determine pollution characteristics of the soil. In the TPH pattern, kerosene, which is a light distillate, had an early retention time, and lubricant oil, which is a heavy distillate, had a late retention time in the gas chromatogram. In addition, we obtained a complexly contaminated soil via diesel and lubricant oil from the Navy and inspected it for its ratio of complex oil species. The inspection results showed that this soil was contaminated with 85% diesel and 15% lubricant oil. The method developed in this study could be used to determine complex petroleum sources and ratios at sites with accidentally contaminated soil.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.14-17
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• 2002

To increase the efficiency of a two-stage anaerobic wastewater digestion system, various polymers were added to the methanogenic reactor as supports. The addition of polyurethane addition (6%, w/v) to the methanogenic reactor facilitated the organic loading rate (2-day Hydraulic Retention Time), higher than that of the conventional methanogenic reactor (6-day HRT). During the operation of the polyurethane-added reactor, a significant decrease in the organic mass in the effluent (COD 5-6 kg/l) was achieved, compared to that of the conventional reactor (COD 15-20 kg/l). The methane gas production rate also improved about 3-fold in the polyurethane-added reactor. More biomass was found to accumulate in the polyurethane-liquid phase (volatile solid, 26-28kg) than in the free-liquid phase (volatile solid, 5- 7 kg/l) after 90 days of operation. A scaled-up experiment with a polyurethane-added 2.5-1 reactor confirmed the previous results, and no adverse effects such as plugging or channeling due to decreased efficiency was observed even after 4 months of operation.

• Journal of Ecology and Environment
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• 제29권4호
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• pp.381-387
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• 2006

We analyzed the total yields and composition of essential oils in leaf extracts of Nepeta cataria by Gas Chromatography Mass Spectrometry (GC-MS). Thirty-six compounds representing 97.0% of total oil were detected. The major constituents of essential oils in Nepeta cataria were nepetalactone (90.9%), unidentified compound (Retention time 17.35; 1.82%), 1,8-cineol (1.49%), ${\beta}-caryophyllene$ (1.12%), and ${\beta}-pinene$ (1.078%). The volatile compounds in leaf extracts of N. cataria concentrated to nepetalactone ($88.83{\sim}93.33%$) remarkably. In the essential oil of N. cataria cis,trans-nepetalactone ($30.2{\sim}37.8%$) and cis,cis-nepetalactone ($31.5{\sim}37.0%$) were found as the main constituents. The effects of essential oil of N. cataria on the growth of six microorganisms (Bacillus cereus, B. subtilis, B. amyloliquefaciens, Escherichia coli, Staphylococcus aureus subsp. aureus, and Pseudomonas aeruginosa) were investigated. The essential oil of N. cataria had strong inhibitory effect on the growth of three fungal species (Bacillus cereus, B. subtilis, and B. amyloliquefaciens). The essential oil from N. cataria was found to have a low antimicrobial activity against Staphylococcus aureus subsp. aureus, while no activity were found against Escherichia coli and Pseudomonas aeruginosa. Results indicate the significant antimicrobial effect, which may be depended on the yield of nepetalactone.

• 한국대기환경학회지
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• 제25권5호
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• pp.420-431
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• 2009

Characteristics and advantages of the thermal desorption-comprehensive two dimensional gas chromatography-time of flight mass spectrometry (TD-GCxGC-TOFMS) were discussed and the organic compound's analysis result was shown for the ambient $PM_{2.5}$ sample collected in Seoul, Korea. Over 10,000 individual organic compounds were separated from about $70{\mu}g$ of aerosols in a single procedure with no sample pre-treatment. Among them, around 300 compounds were identified and classified based on the mass fragmentation patterns and GCxGC retention times. Several aliphatic compounds groups such as alkanes, alkenes, cycloalkanes, alkanoic acids, and alkan-2-ones were identified as well as 72 PAH compounds including alkyl substituted compounds and 8 hopanes. In Seoul aerosol, numerous oxidized aromatic compounds including major components of secondary organic aerosols were observed. The inventory of organic compounds in $PM_{2.5}$ of Seoul, Korea suggested that organic aerosol were constituted by the compounds of primary source emission as well as the formation of secondary organic aerosols.