• Membrane Journal
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• v.22 no.1
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• pp.46-53
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• 2012

Low-temperature carbon dioxide stripping by a vacuum membrane stripping technology was studied as a substitute for the stripping process in a conventional aqueous amine process. Composite membranes with $5{\mu}m$ thickness of PDMS (polydimethylsiloxane) dense layer on a PE (polyethylene) support layer were prepared by a casting method and used as a membrane contactor for $CO_2$ stripping. Aqueous amine solutions of 30 wt% MEA (monoethanolamine) were used as absorbents. $CO_2$ flux was examined under various operating conditions by varying the vacuum pressure (60~360 mmHg (abs.)), stripping temperature ($25{\sim}80^{\circ}C$), $CO_2$ loading (0.5~0.7). $CO_2$ stripping flux increased with increasing temperature and $CO_2$ loading as well as decreasing vacuum pressure. PDMS-PE composite membrane has stability for vacuum stripping process compared with PTFE porous membrane.

• 한국해양학회지
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• v.26 no.3
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• pp.193-203
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• 1991

KODOS (Korea Deep ocean Study)-89 sediments, recovered from western part of Clarion-Clipperton fracture zone in north Pacific, show two distinctly colored layer zones: surface yellow brown layer (unit A) and subsurface dark brown layer (unit B), and roughly recognized as Quaternary and Tertiary in age, respectively. Geochemical characteristics are also different in those two units. Smectite, water, micronodule, and heavy metal contents are higher in unit B, while POC content is higher in unit A. High smectite and low POC contents in unit B are due to the longer formation period of smectite, almost decomposition of labile organic matter in unit B relative to unit A. High water content in unit B is caused by coarse fabric which results from higher content of spicules and spines. Additionally, stronger electrostatic repulsion force caused by high smectite content also supports high water content in unit B relative to unit A. Variations in heavy metal contents are closely related to the amount of micronodule, which has higher metal contents than that of sediment. Therefore, we conclude that the differences of geochemical characteristics in unit A and unit B are resulted from the different diagenetic durations of unit A and unit B.

• Fire Science and Engineering
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• v.26 no.4
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• pp.55-62
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• 2012

The suppression mechanisms of carbon dioxide ($CO_2$) as a representative fire suppression agent were revisited using a counterflow diffusion flame which could be applied the concept of a local application system. To end this, the low strain rate $CH_4$/air counterflow diffusions with $CO_2$ addition in either fuel or oxidizer stream were examined numerically using detailed-kinetic chemistry. Radiative heat loss due to radiating gas species including $CO_2$ added was considered by the optically thin model (OTM). As a result, the critical $CO_2$ volume fractions in the oxidizer stream required to extinguish the flame were in good agreement with the experimental data reported in the literature, while somewhat under-prediction was observed with $CO_2$ added in the fuel stream. The surrogate agents were adopted to estimate the quantitative contribution with changing in global strain rate ($a_g$) on the flame extinguishment among pure dilution effect, thermal effects including radiation heat loss and chemical effect due to the $CO_2$ fire suppression agent.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.91-99
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• 2005

Acid Rock Drainage(ARD) is the product formed by the atmospheric(i.e. by water, oxygen and carbon dioxide) oxidation of the relatively common iron-sulphur mineral pyrite($FeS_2$). ARD causes the acidification and heavy metal contamination of water and soil and the reduction of slope stability. In this paper the generation characteristics and the prediction of ARD of various cut slopes were studied. An attempt to classify the rocks into several groups according to their acid generation potentials was made. Acid Base Accounting(ABA) tests, commonly used as a screening tool in ARD predictions, were performed. Fourteen rock samples were classified into PAF(potentially acid forming) group and four rock samples into NAF(non-acid forming) group. The chemical analysis of water samples strongly suggested that ARD with high content of heavy metals and low pH could pollute the ground water and/or stream water.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.717-726
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• 2017

The current allowable cross-contamination level of fatty acid methyl esters (FAME) in aviation turbine fuel (AVTUR) is 50 mg/kg, due to that the presence of FAME in AVTUR can significantly impact the fuel supply system and jet engine. It has been difficult to analyze the level of FAME in AVTUR, since it is consisted of a lot of hydrocarbons. In this study, thus, a new method using multi-dimensional GC-MS (MDGC-MS) was proposed in order to determine the FAME level in AVTUR effectively. Applying to MDGC-MS with Deans switching system enabled us to detect and quantify the FAME with low carbon numbers such as those derived from coconut oil and palm kernel oil. The matrix effect of MDGC-MS method, which could shift the FAME peaks to slightly longer retention times, was reduced by 20 times compared with that of 1-dimensional GC-MS reference method. This developed method could be suitable for qualitative and quantitative analyses to determine the contamination level of trace FAME in AVTUR.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.3
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• pp.402-408
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• 2016

Master packaging system consists of an inner individual package and secondary outer package. During the stages of chilled transport and distribution, the combination of primary individual package and secondary package was used to maintain a modified atmosphere for shiitake mushrooms. During the retail stage at higher temperature ($25^{\circ}C$), the primary individual package was exposed to display conditions after dismantling of the secondary packaging. The master packaging system was constructed to contain eight individual $30-{\mu}m$ thick polypropylene film bags of 500 g shiitake mushrooms inside a $40-{\mu}m$ low-density polyethylene bag. Carbon dioxide absorbent material [$Ca(OH)_2$] and/or moisture absorbent (superabsorbent polymer) were designed in their required amounts based on respiration characteristics and then applied to the outer secondary packaging in sachet form. Gas concentration of the packaging, temperature, and humidity were monitored throughout transport and storage. The quality of shiitake mushrooms was measured at the retail stage to determine the packaging effect. During the distribution stage of 108 h, $O_2$ and $CO_2$ concentrations in the master packaging system were maintained at 9~11% and 1~4% in the inner packaging, respectively, which are good for quality preservation. Compared to the control, the master packaging with $CO_2$ and/or moisture absorbents improved mushroom preservation and particularly reduced decay.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1124-1129
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• 2011

The importance of environment-friendly agriculture is being magnified as a new growth engine industry in pursuit of low carbon, green growth policies. In order to provide technical supports for pushing ahead with the environment-friendly agriculture policies, we estimated the effects of customized fertilization on growth and yield of rice and fertilizer reduction compared to conventional fertilization and single-element fertilization. In rice plant growth and rice yield, no statistically significant difference between the three fertilization treatments was observed. In contrast, customized fertilization showed high disaster resistance reducing the damage caused by rice lodging during a typhoon. The average N application in farms showing high rice lodging amounted to $135kg\;N\;ha^{-1}$ while $135-138kg\;N\;ha^{-1}$ was known as the critical range of rice lodging in Korea. The fertilizer reduction rate of customized fertilization compared to conventional fertilization of investigated farms was on average 22.5%. We estimated the short-term effects of customized fertilization in the first year after application. In future, there is need for continuous examination of rice growth and soil environment change due to successive application of customized fertilizer.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.417-428
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• 2021

The combustion characteristics of anthracite, which follow a complex process with low reactivity, must be considered through the dynamic behavior of circulating fluidized bed (CFB) boilers. In this study, computational fluid dynamics (CFD) simulation was performed to analyze the combustion characteristics of anthracite in a pilot scale 0.1 MW_th Oxy-fuel circulating fluidized bed (Oxy-CFB) boiler. The 0.1MW_th Oxy-CFB boiler is composed of combustor (0.15 m l.D., 10 m High), cyclone, return leg, and so on. To perform CFD analysis, a 3D simulation model reactor was designed and used. The anthracite used in the experiment has an average particle size of 1,070 ㎛ and a density of 2,326 kg/m³. The flow pattern of gas-solids inside the reactor according to the change of combustion environment from air combustion to oxygen combustion was investigated. At this time, it was found that the temperature distribution in air combustion and oxygen combustion showed a similar pattern, but the pressure distribution was lower in oxygen combustion. addition, since it has a higher CO₂ concentration in oxygen combustion than in air combustion, it can be expected that carbon dioxide capture will take place actively. As a result, it was confirmed that this study can contribute to the optimized design and operation of a circulating fluidized bed reactor using anthracite.

• Korean Journal of Organic Agriculture
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• v.29 no.2
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• pp.209-221
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• 2021

The purpose of this study is to obtain basic data on housing facilities and management of broiler welfare certified farms in Korea. We investigated breeds, flock sizes, stocking density, perches, litter, plumage condition, and other diseases. In addition, we measured temperature, relative humidity, light intensity, ammonia, and carbon dioxide concentration in the barn. As result, criteria were met in all cases that we investigated. However, farmers commonly demanded relaxation of perch and litter. Perch usage of broiler was impractical due to low usage of it. Also, litter was increased, resulting in farmers' economic burden by the imbalance between supply and demand. This situation makes farmers reuse the litter. Unfortunately, there are no clear certification standards. During re-inspection, the animal welfare certification of farms was canceled due to the reuse of litter. It is difficult to modify the standard of perch due to the strong declarative meaning of animal welfare rather than the necessity of perch usage, however, the reuse of litter should be improved. It is important to think and solve any problems faced by all farms. Especially, animal welfare standards need to be improved in more clarity and rationality.

• Food Engineering Progress
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• v.14 no.3
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• pp.249-255
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• 2010

Ten commercial activated carbons (ACs) prepared from four different sources (bamboo, wood, peat, and coal) were evaluated for their adsorptive efficiency of six volatile compounds (isoamyl alcohol, hexanal, furfural, ethyl lactate, ethyl octanoate, 2-phenyl ethanol) which were dissolved in a 30% alcoholic model solution. These six volatile compounds are frequently found in alcoholic beverages and possibly contribute to physiological hangover due to their high concentrations. They are also generally regarded as off-flavor compounds at certain levels in alcoholic beverages such as whisky and vodka. Two hundred mL of 30% alcoholic solutions containing these six volatile compounds were treated with 0.2 g of ACs while stirring for 16 hr; the treated solutions were then measured for their adsorptive efficiencies (or removal efficiencies) by gas chromatographic analysis using two different sampling methods (direct liquid injection and headspace-solid phase microextraction). The adsorptive efficiencies of the ACs varied depending on the identity of the volatile compounds and the source material used for making the ACs. Ethyl octanoate, 2-phenyl ethanol, and hexanal were removed at high efficiencies (34-100%), whereas isoamyl alcohol, ethyl lactate, and furfural were removed at low efficiencies (5-13%). AC prepared from bamboo showed a high removal efficiency for isoamyl alcohol, aldehydes (hexanal and furfural), and 2-phenyl ethanol; these major fusel oils have been implicated as congeners responsible for alcohol hangover.