• 한국태양에너지학회 논문집
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• 제31권5호
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• pp.85-90
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• 2011

The effects of $CO_2$ ppm in atmosphere on the values of the total emissivity are studied. The predictions by several methods are compared. The predicted value differences between modified Kondratyev model and Hottel model are the smallest with in the range of values tested. The $CO_2$ ppm is varied from 300 ppm to 600 ppm. By Wide Band model, the total emissivity increases with increasing density-path length product rather linearly up to 0.1 g/$cm^2$. For given $CO_2$ ppm, the total emissivity increases as the air thickness increases. The same is true for both temperature and pressure increase. The temperature range tested is 220 to 300 K. Around 260K, the total emissivity is less sensitive with increasing temperature than with decreasing temperature. The pressure is varied from 0.94 to 1.06 atm. The percentage change of total emissivity with pressure change from 1atm is at most the percentage change of the pressure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 논문집 센서 박막재료연구회 및 광주 전남지부
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• pp.75-79
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• 2008

In this paper, we measured the activation energy of the Bisphenol A type Epoxy resin (DGEBA)-Jeffamine system according to an irradiation. We put the mixed solutions to the silicon mold after mixing both DGEBA(216g) and Jeffamine(93.9g), curing agent of amine system. The mixed solutions were cured in the atmosphere during 24hours after finishing the first curing during 4hours in the vacuum oven under $80^{\circ}C$. The mixed solutions were cured in the atmosphere during 24hours after finishing the second curing during 12hours in the vacuum oven under $60^{\circ}C$ again. Prepared samples were irradiated to the dose rate of 8kGy/hr with 500kGy, 700kGy, 1000kGy, 1500kGy, 2000kGy, 2500kGy. Experimental results indicated activation energy of the samples reduced as the irradiation dose increased because of the peroxides of the Epoxy created by the oxidation and the radiation.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.728-734
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• 2011

$LiFePO_4$ is a promising cathode material for secondary lithium batteries due to its high energy density, low cost and safety. $LiFePO_4$ was synthesized by the citrate process under reductive, neutral, and oxidative, atmospheres and the crystal structure was analyzed by X-ray powder diffraction. The samples synthesized under $N_2$ and $H_2$ atmosphere showed a single phase of a olivine structure, where the samples synthesized under $O_2$ atmosphere exhibited second phase of $Fe2O_3$. All the samples synthesized at 400, 600 and $800^{\circ}C$ under $N_2$ atmosphere presented a single phase of olivine. Residual organic material was observed for the sample synthesized at $400^{\circ}C$. There was nearly no intensity difference between the samples synthesized at $600^{\circ}C$ and $800^{\circ}C$. The electrochemical characteristic of the $LiFePO_4$ synthesized at $600^{\circ}C$ in the $N_2$ atmosphere was analyzed. The result exhibited an high discharge capacity of 160 mAh/g at the first cycle, and 155-160 mAh/g after 45 cycles.

• 한국포장학회지
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• 제21권1호
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• pp.1-10
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• 2015

Enzyme kinetics-based respiration model can be effectively used for estimating respiration rate in $O_2$ consumption and $CO_2$ production of fresh produce as a function of $O_2$ and $CO_2$ concentrations. Arrhenius equation can be applied to describe the temperature dependence of the respiration rate. Parameters of enzyme kinetics-based respiration model and activation energy of Arrhenius equation were compiled from analysis of literature data and closed system experiment. They enable to estimate the respiration rate for any modified atmosphere conditions at temperature of interest and thus can be used for design of modified atmosphere packaging of fresh produce.

• 한국분말재료학회지
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• 제27권3호
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• pp.233-240
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• 2020

Nano-sized ZnSe particles are successfully synthesized in an aqueous solution at room temperature using sodium borohydride (NaBH₄) and thioglycolic acid (TGA) as the reducing agent and stabilizer, respectively. The effects of the mass ratio of the reducing agent to Se, stabilizer concentration, and stirring time on the synthesis of the ZnSe nanoparticles are evaluated. The light absorption/emission properties of the synthesized nanoparticles are characterized using ultraviolet-visible (UV-vis) spectroscopy, photoluminescence (PL) spectroscopy, and particle size analyzer (PSA) techniques. At least one mass ratio (NaBH4/Se) of the reducing agent should be added to produce ZnSe nanoparticles finer than 10 nm and to absorb UV-vis light shorter than the ZnSe bulk absorption wavelength of 460 nm. As the ratio of the reducing agent increases, the absorption wavelengths in the UV-vis curves are blue-shifted. Stirring in the atmosphere acts as a deterrent to the reduction reaction and formation of nanoparticles, but if not stirred in the atmosphere, the result is on par with synthesis in a nitrogen atmosphere. The stabilizer, TGA, has an impact on the Zn precursor synthesis. The fabricated nanoparticles exhibit excellent photo-absorption/discharge characteristics, suggesting that ZnSe nanoparticles can be alloyed without the need for organic solutions or high-temperature environments.

• Nuclear Engineering and Technology
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• 제35권2호
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• pp.171-177
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• 2003

A dynamic compartment model was required for the prediction of radiological consequences of the tritiated vapor released from the nuclear facility after an accident. A computer code, ECOREA-T, was developed by incorporating the unit models for the evaluation of tritium behavior in the environment. Dry deposition of tritiated vapor from the atmosphere to the soil was calculated using a deposition velocity. Transport of tritium from the atmosphere to the plant was calculated using a specific activity model, and the result was compared with the Belot's analytic solution. Root uptake of tritiated water from the soil and formation of OBT from T were considered in the model. The ECOREA-T code was verified by comparing the results from the other computer codes using a scenario developed through BIOMOVS II study. The results showed good agreements.

• 한국환경과학회지
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• 제6권4호
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• pp.351-357
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• 1997

In the Atmosphere under the various physical and chemical condition different chemical reactions occur and there are a number of air pollutants which are generated by photochemical reaction by absorbing solar energy. Therefor various testing simulation was done as foundation work to develop the numerical model for the prediction of concentration of air pollutants. It was shown change of msjor air pollutants concentration In according to variation of photodissociation speed constant, Kl and Initial condition of air pollutants concentration which plays major role In photochemical reaction. The photochemical reaction model which was used In this study Is found to be useful for understanding relationship among the concentration of reacting air pollutants and the prediction of concentration of air pollutants in urban atmosphere.

• Nuclear Engineering and Technology
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• 제34권3호
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• pp.242-249
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• 2002

The relationship between the tritium release rate from the nuclear power plant and tritium concentration in the environment around the Kori site was modeled. The tritium concentration in the atmosphere was calculated by multiplying the release rates and $\chi$/Q values, and the d3V deposition rate at each sector according to the direction and the distance was obtained using a dry deposition velocity. The area around Kori site was divided into 6 zones according to the deposition rate. The six zones were divided into 14 compartments for the numerical simulation. Transfer coefficients between the compartments were derived using site characterization data. Source terms were calculated from the dry deposition rates. Tritium concentration in surface soil water and groundwater was calculated based upon a compartment model. The semi-analytical solution of the compartment model was obtained with a computer program, AMBER. The results showed that most of tritium deposited onto the land released into the atmosphere and the sea. Also, the estimated concentration in the top soil agreed well to that measured. Using the model, tritium concentration was predicted in the case that the tritium release rates were doubled.

• 열처리공학회지
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• 제9권1호
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• pp.45-52
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• 1996

Different crystallographic planes, at a gas-metal interface, have different surface energy. To grow the (100) grains of 6.5wt%Si-Fe alloy preferentially, it was heat-treated in the atmosphere of sulfur by using the surface energy. When the specimen is heat-treated for 1 hour at $1175^{\circ}C$ by using the atmosphere of sulfur produced by heating at $75^{\circ}C$, (100) grains were grown to 3.5mm. Owing to the growth of (100) grains, the coercive force was decreased to 2.1 A/mm, and the magnetic induction at 800(A/mm) was increased to 1.61T.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.428-434
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• 2012

The aim of this study was to determine the quality of modified atmosphere (MA) packaged meat from Pomeranian rams slaughtered at 50 and 100 days of age. Determined: chemical composition, physicochemical and sensory properties of meat, and the fatty acid profile of intramuscular fat. Meat from 100-d-old lambs was characterized by a significantly higher content of dry matter, total protein and crude fat, a darker color and higher physiological maturity ($p\leq0.01$). Meat from younger lambs was marked by a better water-holding capacity ($p\leq0.05$), a lower energy value and higher concentrations of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). An increase in the content of dry matter, total protein and ash, and energy value was noted in MA-stored meat. Meat pH decreased over MA storage and the sensory properties deteriorated. The studied meat remained safe from microbial contamination during storage.