• The Korean Journal of Ceramics
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• v.1 no.3
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• pp.147-151
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• 1995

Porous composite of $Al_2O_3$ and AIN based mullite and SiC can be prepared by alumium reaction synthesis and atmosphere controllied sintering in order to improve the durability of a gas filter body. The porous $Al_2O_3$-AIN-mullite, which has a strength of 168 kg/$\textrm{cm}^2$ and porosity of 51.59%, could be obtained by stmospheric firing at $1600^{\circ}C$ and the porous $Al_2O_3$-AIN-SiC with a porosity of 33% and strength of 977 kg/$\textrm{cm}^2$, could also be prepared. The average pore size has been changed from 0.2$\mu\textrm{m}$ in a reduction atmosphere and to 2$\mu\textrm{m}$ in an air atmosphere, respectively.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.512-513
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• 2003

Human activities have become a major factor that significantly changes the global environment. Mankind has increasingly used land, water, minerals and other natural resources since the beginning of industrialization, and future growth in the population and economy is thought to further enhance the impact upon the Earth. The global climate, biogeochemical process and natural ecosystems are closely linked with one another, and changes in any one of these systems may effect the others, which could result in consequences detrimental to humans and other living organisms on the Earth.(omitted)

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1067-1070
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• 2006

Experimental samples were produced with mullite and cordierite powders with SiC. Effects of temperature, atmosphere and additive on the composite properties were investigated by XRD, STA and PSA methods. Results show that samples containing calcinate cordierite and calcinate mullite with SiC baked in air atmosphere have not suitable properties at the temperature range of $1380-1450^{\circ}C$ due to SiC intensive oxidation, while argon atmosphere decrease SiC oxidation. Using $Bi_2O_3$ as the additive, cordierite phase formation and prevention from SiC oxidation at low temperatures were achieved, leading to the improvement of physical and mechanical properties

• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.39-46
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• 1994

LiTaO3 single crystals were growth without cracking using Pt-Rh crucible and Ir crucible. The starting composition to get the melt of congruent melting composition, which has been dependent upon the experimental procedure, was taken after fixing the total growing process by the result of preliminary experiments. The Rh contamination from the Pt-Rh crucible was to be neglected if the crystal had been grown under inert atmosphere, which resulted in the crystal color being slightly yellow. This color was decolored after 24 hour's annealing at 1200℃ under air atmosphere. The optimum conditions for the crystal growing and the diameter control were so dependent upon the crucible material in spite of using the crucible of the same size. The liquid-solid interface of LiTaO3 crystal of 1" diameter has been flat if the rotation speed was 45rpm.

• Korean Journal of Poultry Science
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• v.23 no.4
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• pp.193-201
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• 1996

This experiment was carried out to find out the effect of packing methods on physico-chemical properties of breast and thigh meats in chicken, which was dried by air spray chilling method. The chicken carcass was cut into breast and thigh muscles, which were either vacuum packed or atmosphere packed, and stored at -2O˚C for 1, 4, 8, 12 and 16 wk after quick freezing at -45˚C for 35 min. The pH values of atmosphere-packed breast meat and vacuum-packed breast meat after one wk of storage were higher than those of atmosphere-packed thigh meat and vacuum-packed thigh meat(P< .05). The pH values increased as storage period extended, but no significant difference was detected between two packing method(vacuum vs. atmosphere). Total moisture contents of breast meats after one wk of storage were higher than those of thigh meats. The total moisture contents decreased slowly as storage period extended, but no significant difference was detected between two packing method(vacuum vs. atmosphere). The shear force value of thigh meat was higher than that of breast meat. The shear force values of both meats decreased as storage period extended, regardless of packing method. The water soluble protein extractability of thigh meats was higher than that of breast meat, and the water soluble protein extractability of all treatments decreased until 8 wk after storage, but increased gradually after 8 wk of storage period. The salt soluble protein extractability of breast meat was higher than that of thigh meat, and the salt soluble protein extractability of all treatments decreased as storage period extended. With regard to the packing method, the vacuum packing showed higher value than that of atmosphere packing method until 8 wk of storage. Total lipid contents of atmosphere- and vacuum-packed thigh meats at 1 wk of storage were higher than those of breast meats, and the total lipid contents of all of treatments decreased as storage period extended. However, no significant difference was detected between two packing methods. The fatty acid contents of breast and thigh meats were in order of o1eic(33,5~42.4), palmitic(19.7~30.8) and linoleic acid(10.8~17.4).

• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.681-687
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• 2008

It is well known that the water infiltration rate depends on soil properties such as soil water content, water head, capillary suction, density, hydraulic conductivity, and porosity. However, most of proposed infiltration models assume that the air phase is continuous and in equilibrium with the atmosphere or air compression and air entrapment on infiltration was not considered. This study presents experimental results on unsaturated water infiltration to relate air entrapment and hydraulic conductivity function based on soil air properties. The objectives of this study were to measure change of soil air pressure ahead of wetting front under air drain and air confined condition to find the confined air effect on infiltration rate, to reduce the entrapped air volume related with soil air pressure to increase the soil permeability, and to make a basis of infiltration process model for the purpose of improvement of infiltration rate in the homogeneous soil column. The results of the work show that soil air pressure increases according to increasement of the saturated soil depth rather than the wetting front depth during infiltration process.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.E1
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• pp.1-9
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• 2003

The soil concentrations of polychlorinated biphenyls (PCBs) were measured at 12 sites in Ansung, Kyonggi province, Korea. Correlation coefficient (r) between total PCBs and organic matter content (OM) was significant (r=0.562, p< 0.05). It suggests that organic matter may be a key factor of soil absorption of PCBs. The PCB concentrations of low chlorinated congeners with high vapor pressure were relatively abundant in air but high chlorinated congeners with low vapor pressure were mainly dominated by soil. The results indicated the influence of physicochemical properties of PCBs such as vapor pressure, octanol - air partition coefficient ( $K_{OA}$ ). The calculated soil/air fugacity quotients suggested that the soil may be a source of heavier molecular PCBs (>penta-CBs) to the atmosphere, where lighter molecular PCBs appear to be affected by a movement from air to soil, especially tetra-CBs. Therefore, PCB homologs with low vapor pressure might have been influenced by revolatilization from soil.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.157-160
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• 2010

Management of indoor air quality of underground subway station is an important issue since the limited natural ventilation, limited sunshine incoming, and highly moistured atmosphere. The improvement in IAQ of platform is expected because most stations were installed with platform screen door currently, however, the poor air quality in tunnel might be affecting subway cabin indoor. In this study, we developed the air quality assessment model based on computational fluid dynamics. The geometry of air ventilation unit, seat, LCD monitors, and passengers were modeled using commercial software (Design Modeler) and fluid pattern and pollutants trajectories were analyzed by using CFX. We predicted the thermal comfort by predicted mean vote (PMV), distribution of CO2 and PM10 concentration. It is expected that this model can be used for the performance test of air cleaners which are under development.

• Journal of Climate Change Research
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• v.4 no.4
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• pp.305-316
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• 2013

The purpose of this study is to monitor the flux of $CO_2$ between the atmosphere and forest. The main research activities are conducted at Taehwa Mt. (Gangju, Kyeonggi, Korea), The Taehwa site is located 60 km north-east from the center of Seoul Metropolitan Area. The TRF flux tower is in the middle of a Korean Pine (Pinus koraiensis) plantation ($400m{\times}400m$), surrounded by a mixed forest. Eddy covariance method was used for $CO_2$ flux above the forest. $CO_2$ flux was measured from September to November 2011 and March to June 2012. It was found that $CO_2$ fluxes were observed between the atmosphere and forest. $CO_2$ was absorbed by plants through photosynthesis during the day and released during the night. $CO_2$ flux were respectively observed 0.7~0.2, 0.5~0.1, $0.3{\sim}0.1mgCO_2m^{-2}s^{-1}$ in Septem- ber, October, November 2011. $CO_2$ fluxes released by plants in the early morning(00:00~07:30h) and evening(18:00~24:00h) time. But $CO_2$ was absorbed by plants through photosynthesis in the day time(08:00~7:30h).

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.428-432
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• 2009

40 goat kid ribcages were held for 7 days in storage conditions ($4^{\circ}C$) and used to determine the effects of three different packaging methods (atmospheric air, vacuum and modified atmosphere package (MAP) 10:70:20 mixture of $N_2:O_2:CO_2$) on meat quality of the chops. L* was affected by the packaging method being lighter than MAP chops. The coordinate a* significantly increased during storage time. For MAP-packed chops and those kept in atmospheric air, b* increased markedly during storage time whereas it remained unaffected throughout storage when in vacuum packages. Final pH values ranged from 5.6 to 5.8 and no effects were found for either storage time or packaging method. WHC means were lowest for the three packaging methods on day 7 of storage and highest on day 1. Storage time increased water loss in vacuum treatments. Trained panel colour acceptability was lower at 3, 5 and 7 days than on day 1 of storage for atmospheric air treatment and vacuum packaging, while for the MAP treatment average values on days 5 and 7 were lower than those observed on days 1 or 3. Trained panel odour was lower for atmospheric air and vacuum packages at 3, 5, and 7 days storage than at 1 day, while no differences were found in trained panel odour acceptability for MAP packages. With reference to consumers, the MAP proposed in the present study is the chosen method for storing goat meat, rather than vacuum or atmospheric air packaging.