• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.119-125
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• 2017

Ablative material in a rocket nozzle is exposed to high temperature combustion gas, thus undergoes complicated thermal/chemical change in terms of chemical destruction of surface and thermal decomposition of inner material. Therefore, method for conjugate analysis of thermal response inside carbon/phenolic material including rocket nozzle flow, surface chemical reaction and thermal decomposition is developed in this research. CFD is used to simulate flow field inside nozzle and conduction in the ablative material. A change in material density and a heat absorption caused by the thermal decomposition is considered in solid energy equation. And algebraic equation under boundary layer assumption is used to deduce reaction rate on the surface and resulting destruction of the surface. In order to test the developed method, small rocket nozzle is solved numerically. Although the ablation of nozzle throat is deduced to be higher than the experiment, shape change and temperature distribution inside material is well predicted. Error in temperature with experimental results in rapid heating region is found to be within 100 K.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.123-128
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• 2008

The Dissolved Organic Carbon (DOC) existing in a water includes both hydrophobic and hydrophilic substances however, most of the discussion focuses on hydrophobic substances. The hydrophobic fraction was easily removed by absorption or coagulation more than hydrophilic fraction. Therefore, control of the hydrophilic fraction is very important in water treatment process. This study is to determine the variation of DOC, the removal efficiency of DOC, and Trihalomethane formation potential (THMFP) after each stage of water treatment process by fractionating Natural Organic Matters (NOM) into hydrophobic and hydrophilic substance. DOC from raw water was fractionated at acidic pH (pH<2) using XAD 8 resin column, into two fraction : hydrophobic substance (i.e. humic substance) adsorbed on XAD 8 and hydrophilic substance which represent the organics contained in the final effluent. THMFP was carried out according to the following set condition: Cl2/DOC=4 mg/mg, incubation at $25^{\circ}C$ in darkness, pH 7 adjust with HCl or NaOH as necessary, and 72hour-contact time. THMs analyzed in this study were chloroform, bromodichloromethane, dibromochloromethan, and bromoform. Sewage was almost evenly split between the hydrophobic (56%) and hydrophilic fraction (44%). But, Aldrich humic substance (AHS) was found to contain less hydrophilics (14%) than hydrophobics (86%). The formation of THMs may depend on the source which is characterized by the composition of organic matters such as AHS and sewage. The THMFP yield of sewage and AHS were assessed as follows. The value of the THMFP reaction yield, AHS $172.65{\mu}g/mg$, is much higher than that of sewage $41.68{\mu}g/mg$. This illustrates possible significant difference in THMFP according to the component type and the proportion of organic matter existing in water source. Apparently AHS react with chlorine to produce more THMFP than do the smaller molecules found in sewage. Water treatment process may reduce THMFP, nevertheless residual DOC (the more hydrophilic substance) has significant THMFP. Further reduction in organic halide precursors requires application of alternative treatment techniques.

• Journal of the Korean Chemical Society
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• v.25 no.2
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• pp.75-84
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• 1981

Ultraviolet spectrophotometric investigations have been carried out on the systems of mesitylene with iodine, bromine, iodine monochloride and iodine monobromide in carbon tetrachloride. The results reveal the formation of the charge transfer complexes of the type, $C_6H_3(CH_3)_3{\cdot}X_2$ or $C_6H_3(CH_3)_3{\cdot}IX$ (X denotes halogen atoms). The equilibrium constants were obtained in consideration of that absorption maxima due to the formation of the charge transfer complexes shift to blue with the increasing temperatures. Thermodynamic parameters, ${\Delta}H$, ${\Delta}G$ and ${\Delta}S$ for the formation of the charge transfer complexes were calculated from these values. These results indicate that the relative stabilities of the mesitylene complexes at each temperature decrease in the order, ICl > IBr > $I_2$ > $Br_2$. This order may be a measure of their relative acidities toward mesitylene, which is explaned in terms of the relative polarizabilities of halogen molecules and the relative electronegativities of halogen atoms. These results combined with previous study of this series indicated that the relative stabilities of the polymethylbenzene complexes with iodine increase in the order Benzene < Toluene < Xylene < Mesitylene Thus, analysis of these findings is discussed.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.569-581
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• 1990

It is generated in DMF by activated catalysts of superoxo cobalt(III) complex, such as [Co(III)(Schiff base)(L)]O$_2$ (Schiff base; SED, SOPD and o-BSDT, L; DMF and Py) which mole ratio of oxygen to metal is 1:1 that oxidation major product of 2,6-di-tert-butylphenol by homogeneous oxidatve catalysts of oxygen adducted tetradentate Schiff base cobalt(III) is 2,6-ditert-butylbenzoquinone (BQ). And oxidation product of 3,3',5,5'-tetra-tert-butyldiphenoquinone (DPQ) is generated by activated catalysts such as $\mu$-peroxo cobalt(III) complex; $[Co(III)(SND)(L)]_2$$O_2$ (L; DMF and Py) which mole ratio of oxygen to metal is 1:2. It is difficult to identify these homogeneous activated catalysts such as superoxo and $\mu$-peroxo cobalt(III) complexes in DMF and DMSO solvents. But we can identify by P.V.T method of the oxygen absorption in pyridine solvent and by the reduction process occurred to four steps including prewave of O$_2$- in 1:1 oxygen adducted superoxo cobalt(III) complexes and three steps not including prewave of O$_2$- in 1:2 oxygen adducted $\mu$-peroxo cobalt(III) complexes by the cyclic voltammetry with glassy carbon electrode in 0.1 M TEAP as supporting electrolyte solutidn.

• Korean Journal of Remote Sensing
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• v.35 no.6_2
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• pp.1053-1065
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• 2019

Land use statistics calculation is very informative data as the activity data for calculating exact carbon absorption and emission in post-2020. To effective interpretation by land use category, This study classify automatically image interpretation by land use category applying forest aerial photography (FAP) to deep learning model and calculate national unit statistics. Dataset (DS) applied deep learning is divided into training dataset (training DS) and test dataset (test DS) by extracting image of FAP based national forest resource inventory permanent sample plot location. Training DS give label to image by definition of land use category and learn and verify deep learning model. When verified deep learning model, training accuracy of model is highest at epoch 1,500 with about 89%. As a result of applying the trained deep learning model to test DS, interpretation classification accuracy of image label was about 90%. When the estimating area of classification by category using sampling method and compare to national statistics, consistency also very high, so it judged that it is enough to be used for activity data of national GHG (Greenhouse Gas) inventory report of LULUCF sector in the future.

• 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.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.48-57
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• 2005

Phthalate esters are known as plasticizers and some of them suspected as endocrine disrupting chemicals. In this study, in order to identify the mechanism of phthalate esters degradation by white rot fungus, phthalic acid, which is major metabolite in the biodegradation of phthalate esters, was used. Phthalic acid 50 ppm was treated in culture medium with Polyporus brumalis. The availability of ABTS oxidation was different from control and phthalic acid treated group after 4 days of incubation. The activity was gradually increased in control group, but not in phthalic acid treated group. Especially, esterase activity of control group was maximized at 10 days of incubation, and then decreased while the activity of phthalic acid treated group was increased. Glucose was used as a carbon source, and the difference of glucose consumption by control and phthalic acid treated group was not significant. However, after 6 days of incubation the residual glucose in culture medium was rapidly decreased. The consumption rate of phthalic acid treated group was lower than control. These results might indicate that the absorption of phthalic acid in culture medium was occurred by mycelium and metabolized through some pathways as that of glucose was. To clearify the chemical modification of phthalic acid in culture medium, phthalic acid was reacted under in vitro condition which mycelium was excluded. The metabolites were analyzed by GC/MS. The results showed that phthalic acid was converted to phthalic acid anhydride by the extracellular enzymes of P. brumalis.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.6
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• pp.121-132
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• 2021

Green facade has a significant impact on building's energy performance by controlling the absorption of solar radiation and improving outdoor thermal comfort through shading and evapotranspiration. In particular, since high-density building does not enough green space, green facade, and rooftop greening using artificial ground plants are highly utilized. However, the level of cooling effect according to plant traits and irrigation control is different. Therefore, in this study, the cooling effect analyzed for a total of 4 cases by controlling the irrigation condition based on hedera and spurge. Although hedera under sufficient water had the highest cooling effect(-2℃~-4℃), had the lowest cooling effect under non-irrigation(+1.1℃~+4.4℃). In addition, hedera under sufficient water had cooling effect than hedera under non-irrigation(-1℃~-8.1℃) and in the case of spurge, it had cooling effect(-0.3℃~-7.8℃) more than non-irrigation. As a result of measuring the amount of transpiration according to the light intensity (PAR) and carbon dioxide concentration conditions, transpiration of hedera was higher than the spurge (respectively 0.63204mmolm^-2s^-1, 0.674367mmolm^-2s^-1). The difference in the cooling effect of the green facade under irrigation condition was significant. But the potential cooling effect of green facade according to plants species was different. Therefore, in order to maximize and continuously provide the cooling effect of green facade in urban areas, it is necessary to consider the characteristics of plants and the control of water supply through the irrigation system.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.16-27
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• 2022

Due to climate change, temperature is rising worldwide. Since rapid growth has been achieved focused on cities, South Korea is experiencing serious environmental problems such as heat island and air pollution in urban areas. To solve this problem, the central and each local government are actively promoting tree planting campaigns. This study quantitatively calculated changes in green areas and vegetation of Gumi by the tree planting campaign, and analyzed the temperature changes accordingly. For the target area, the green area, vegetation index, and ground temperature were calculated for 4 different time periods using the given Landsat satellite images. As a result of the study, the green area of was increased by 7.24km² and 4.93km² for two regions, respectively. Accordingly, the vegetation index increased by 0.14 to 0.16, and the temperature decreased by 0.8 to 1.2℃. The Tree planting campaign not only plays a role in lowering the temperature of the city but also does various roles such as air purification, carbon absorption, and providing green rest areas to citizens. Therefore the campaign should be carried out continuously.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.169-169
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• 2022

Over the past 100 years, the global average temperature has risen by 0.75 ℃. The Korean Peninsula has risen by 1.8 ℃, more than twice the global average. According to the RCP 8.5 scenario, the CO₂ concentration in 2100 will be 940 ppm, about twice as high as current. The National Institute of Crop Science(NICS) is using the SPAR (Soil-Plant Atmosphere Research) facility that can precisely control the environment, such as temperature, humidity, and CO₂. A Python-based colony photosynthesis algorithm has been developed, and the carbon and nitrogen absorption rate of rice is evaluated by setting climate change conditions. In this experiment, Oryza Sativa cv. Shindongjin were planted at the SPAR facility on June 10 and cultivated according to the standard cultivation method. The temperature and CO₂ settings are high temperature and high CO₂ (current temperature+4.7℃ temperature+4.7℃·CO₂ 800ppm), high temperature single condition (current temperature+4.7℃·CO₂ 400ppm) according to the RCP8.5 scenario, Current climate is set as (current temperature·CO₂400ppm). For colony photosynthesis measurement, a LI-820 CO₂ sensor was installed in each chamber for setting the CO₂ concentration and for measuring photosynthesis, respectively. The colony photosynthetic rate in the booting stage was greatest in a high temperature and CO₂ environment, and the higher the nitrogen fertilization level, the higher the colony photosynthetic rate tends to be. The amount of photosynthesis tended to decrease under high temperature. In the high temperature and high CO₂ environment, seed yields, the number of an ear, and 1000 seed weights tended to decrease compared to the current climate. The number of an ear also decreased under the high temperature. But yield tended to increase a little bit under the high temperature and high CO₂ condition than under the high temperature. In addition, In addition to this study, it seems necessary to comprehensively consider the relationship between colony photosynthetic ability, metabolite reaction, and rice yield according to climate change.