• 한국농림기상학회:학술대회논문집
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• 한국농림기상학회 2003년도 춘계 학술발표논문집
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• pp.115-128
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• 2003

o What is the flux \ulcorner Flux is the transfer of a quantity per unit area per unit time. The quantities are mass, heat, moisture, momentum and pollutant in micrometeorology. Kinematic flux (Fluid). The reduction in wind speed due to frictional drag transfers momentum from the atmosphere to the surface, creating turbulence that mixes the air and transports heat and water from the surface into the lower atmosphere. (omitted)

• 한국표면공학회지
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• 제47권5호
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• pp.257-262
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• 2014

In this paper, the behavior of hydrogen embrittlement of 680MPa DP sheet steel according to hydrogen charging conditions in acid and alkali electrolytes atmosphere was investigated. At this time, 0.5 M $H_2SO_4$ and 0.5M NaOH was used for electrolytes atmosphere and the effect on embrittlemnet of 680MPa DP sheet steel according to current density and charging time was evaluated by the change of subsurface microhardness in DP specimens chared hydrogen. As a result of this experiment, the microhardness of the layer directly below the surface was increased more than the microhardness of the subsurface zone in both electrolytes cases, but the change of the subsurface microhardness in both electrolytes was more affected by the increase of charging time than the increase of current density. The microhardness of subsurface zone in 0.5 M $H_2SO_4$ acid electrolyte was increased more than the microhardness in 0.5M NaOH alkali electrolyte. It was supposed that acid atmosphere was more sensitive to hydrogen embrittlement than alkali atmosphere on electrolyte atmosphere of hydrogen charge.

• 한국환경과학회지
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• 제20권8호
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• pp.963-975
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• 2011

For this research, they were monitored $CO_2$ flux and environmental factors ($CO_2$ concentration, soil temperature, soil moisture, soil organic carbon, soil pH, soil Eh) in foreshore, paddy field and woods sites at the winter season (January 2009) and the summer season (September 2009). Seasonal and spatial variations for monitored data were analyzed, and linear regression functions of $CO_2$ flux as environmental factors were estimated. $CO_2$ fluxes averaged between surface and atmosphere monitored in foreshore and paddy field at the winter season were shown $-8\;mgCO_2m^{-2}hr^{-1}$ and $-25\;mgCO_2m^{-2}hr^{-1}$, respectively. $CO_2$ fluxes averaged between surface and atmosphere monitored in foreshore and paddy field at the summer season were shown $47\;mgCO_2m^{-2}hr^{-1}$ and $117\;mgCO_2m^{-2}hr^{-1}$, respectively. Thus, $CO_2$ was sunk from atmosphere to surface at the winter season and it was emitted from surface to atmosphere at the summer season. $CO_2$ fluxes in woods site were emitted $145\;mgCO_2m^{-2}hr^{-1}$ at the winter season and $279\;mgCO_2m^{-2}hr^{-1}$ at the summer season.

• 대한금속재료학회지
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• 제46권3호
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• pp.125-130
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• 2008

Conventional plasma carburizing or nitriding for austenitic stainless steels results in a degradation of corrosion resistance. However, a low temperature plasma surface treatment can improve surface hardness without deteriorating the corrosion resistance. The 2-step low temperature plasma processes (the combined carburizing and post nitriding) offers the increase of both surface hardness and thickness of hardened layer and corrosion resistance than the individually processed low temperature nitriding and low temperature carburizing techniques. In the present paper, attempts have been made to investigate the influence of the introduction of Ar gas (0~20%) in nitriding atmosphere during low temperature plasma nitriding at $370^{\circ}C$ after low temperature plasma carburizing at $470^{\circ}C$. All treated specimens exhibited the increase of the surface hardness with increasing Ar level in the atmosphere and the surface hardness value reached up to 1050 HV0.1, greater than 750 $HV_{0.1}$ in the carburized state. The expanded austenite phase (${\gamma}_N$) was observed on the most of the treated surfaces. The thickness of the ${\gamma}_N$ layer reached about $7{\mu}m$ for the specimen treated in the nitriding atmosphere containing 20% Ar. In case of 10% Ar containing atmosphere, the corrosion resistance was significantly enhanced than untreated austenitic stainless steels, whilst 20% Ar level in the atmosphere caused to form CrN in the N-enriched layer (${\gamma}_N$), which led to the degradation of corrosion resistance compared with untreated austenitic stainless steels.

• 한국표면공학회지
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• 제55권4호
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• pp.215-221
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• 2022

In the present work, copper oxide thin films were formed by heat-treatment method with different temperatures and atmosphere, e.g., at 200 ~ 400 ℃; in air and Ar atmosphere. The morphological, electrical and optical properties of the thermally fabricated Cu oxide films were analyzed by SEM, XRD, and UV-VIS spectrometer. Thereafter, photoelectrochemical properties of the thermal copper oxide films were analyzed under solar light (AM 1.5, 100 mW/cm²). Conclusively, the highest photocurrent was obtained with Cu₂O formed under the optimum annealing condition at 300 ℃ in air atmosphere. In addition, EIS results of Cu oxide formed in air atmosphere showed relatively low resistance and long electron life-time compared with Cu Oxide fabricated in Ar atmosphere at the same temperature. This is because heat-treatment in Ar atmosphere could not form Cu₂O due to lack of oxygen, and thermally formed CuO at high temperature suppressed stability and conductivity of the Cu oxide.

• 한국환경과학회지
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• 제5권4호
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• pp.441-451
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• 1996

The surface meteorological and upper layer meteorological observation carried out to investigate influences of sea breeze effect on lower layer atmosphere at Gori nuclear power plant for 29∼30 July, 1996. According to surface meteorological data, the inflow of sea breeze was occurred 11:30 on 29 July, 10:30-on 30 July, respectively, at observation site. And the meteorological tower data showed that wind direction of sea breeze was identified as south-westerly, and wind speed of 58 m was 2 times stronger than that of 10 m. It is notworthy that surface inversion layer which built from the night time to daybreak of next day was not broken off by seab reeze's inflow for daytime, and strong inversion layer observed at 47∼243 m with moderately stable class (F) by URC. It was found that strong stable layer of potential temperature appeared at that layer, maximum relative humidity observed at the bottom of inversion layer and maximum mixing ratio observed in the low of inversion layer.

• 한국대기환경학회지
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• 제15권6호
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• pp.767-777
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• 1999

In the coastal region air flow changes due to the abrupt change of surface temperature between land and sea. So a numerical simulation for atmospheric flow fields must be considered the correct fields of sea surface temperature(SST). In this study, we used variables such as latent heat flux, sensible heat flux, short and long wave radiation of ocean and atmosphere which exchanged across the sea surface between atmosphere and ocean model. We found that this consideration simulated the more precise SST fields by comparing with those of the observated results. Simulated horizontal SST differences in season were 2.5~4$^{\circ}C$. Therefore we simulated the more precise atmospheric flow fields and the movement and dispersion of the pollutants with the Lagrangian particle dispersion model. In the daytime dispersion pattern of the pollutants emitted from ship sources moved toward inland, in the night time moved toward sea by land/sea breeze criculation. But air pollutants dispersion can be affected by inland topography, especially Yangsan and coastal area because of nocturnal wind speed decrease.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.400-400
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• 2009

In a wide variety of high-voltage applications surface flashover plays major role in the system's performance and yet has not been studied in great detail for atmospheric conditions with modem diagnostic tools. surface flashover for both direct current and pulsed voltages in considered. within the setup, parameters such as geometry, material characteristics of the applied voltage can be altered. This paper review surface flashover of insulator, primarily in atmosphere. It discusses theories and models relating to surface flashover and experimental results. surface flashover of insulators in atmosphere generally is initiated by the emission of electrons from the cathode triple junction point (the region where the electrode, insulator, air). the electrode material was copper, and a AC voltage was applied between the electrodes. these results were compared with the surface flashover characteristic of epoxy.

• 한국세라믹학회지
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• 제30권4호
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• pp.279-288
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• 1993

A study on calcination and reduction of AUC(ammonium uranyl carbonate, (NH4)4UO2(CO3)3) has been carried out by using TG-DTA in N2, air and H2 atmospheres, respectively. Phases of various intermediate obtained during thermal analysis of AUC in different atmospheres were confirmed by XRD. Powder characteristics of each intermediate were investigated by measuring particle size and specific surface area, and also observed by SEM. As a results, regardless of applied atmosphere AUC was calcined into amorphous UO3, which was converted to $\alpha$-U3O8 Via $\alpha$-UO3 in both H2 and N2 atmosphere, but directly into $\alpha$-UO3 in air atmosphere. Further reduction of U3O8 was only detectable in hydrogen atmosphere. During calcination and reduction, average particle size was reduced to less than 30% of original value without morphology change. Specific surface area was dramatically increased with release of NH3, CO2 and H2O from AUC powder and reached maximum value around 25$0^{\circ}C$, and then gradually decreased with the increase of temperature due to sintering effect of uranium oxides such as UO3 and U3O8. It was also found that the change of average crystallite size and pore size were closely related to the changes of specific surface area of uranium oxides.

• 한국세라믹학회지
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• 제31권9호
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• pp.1037-1043
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• 1994

The effects of annealing atmosphere and temperature on piezoelectricity (k33) and the mechanical strength of machined PZT was studied. Morphotropic Nb-doped PZT was sintered, machined to a rod and then annealed between 80$0^{\circ}C$ and 100$0^{\circ}C$ in air, PbZrO3, and CuO atmospheres respectively. In air or PbZrO3 atmosphere, the compressive strength of Nb-doped PZT increased by 12% with little change in k33 irrespective of annealing temperature. In CuO atmosphere, on the other hand, the compressive strength increased by 20% with little change in k33 at 80$0^{\circ}C$ but both turned to significant decrease above 90$0^{\circ}C$. The examination of the phase distribution and microstructure beneath the surface of CuO-treated PZT revealed that the changes in compressive strength and k33 are closely related to the reaction between PZT and vaporized CuO:liquid PbO precipitated in shallow surface region by the substitution of Cu to Pb sites enhances the decrease in microcracks and the surface roughness at 80$0^{\circ}C$ ; rapid evaporation of precipitated PbO expands a porous region of changed composition into the bulk above 90$0^{\circ}C$.