• Journal of Korean Society for Atmospheric Environment
• /
• v.12 no.4
• /
• pp.407-419
• /
• 1996

Characteristics of visual air quality in Seoul have been investigated between June 13 and 21, 1994. Optical properties (extinction coefficient and particle scattering coefficient), meteorological parameters (relative humidity, temperature, wind speed, wind direction, and cloud cover), particle characteristics (mass size distribution, components) were measured and analyzed. During measurement periods, northwest wind with less than 2m/sec of wind speed deteriorates visibility. Effects of relative humidity are though to be not a direct factor which influence to visibility through the size change due to hygroscopic species in aerosol. During the smoggy period both the aerosol mass concentration and fine particle fraction of the size distribution are increased compared to the clear period. Sulfate, organic carbon, and elemental carbon in aerosol are the major species in determining the occurrence and severity of a smog in Seoul.

• Journal of ILASS-Korea
• /
• v.3 no.4
• /
• pp.25-34
• /
• 1998

Hygroscopic aerosols can rapidly grow in size by steam condensation even under subsaturated steam conditions. Much efforts have been made to handle this process, but there have been computational difficulties in handling the condensational growth of hygroscopic aerosols by contentional methods. A recently released computer code, CONTAIN 2.0, employs a new technique called Moving Sectional Method(MSM) to handle the growth of hygroscopic aerosols. As a part of the model verification efforts, we have used the code to simulate the VANAM M3U hygroscopic aerosol experiment. We assess the accuracies of the new MSM and the conventional Fixed Sectional Method(ESM) based on the simulation results. Also presented are discussions about the robustness of the MSM.

• Nuclear Engineering and Technology
• /
• v.32 no.5
• /
• pp.425-432
• /
• 2000

It has been an essential part for the safety assessment of nuclear power plants to understand various phenomena associated with the molten core-concrete interaction(MCCI) under severe accidents. In this study, the severe accident analysis code MELCOR was used to simulate the MCCI experiments such as SWISS and SURC test series which had been performed in Sandia National Laboratories(SNL). The calculation results were compared with corresponding experimental data such as melt temperature, concrete ablation distance, gas generation rate, and aerosol release rate. Good agreements were observed between MELCOR calculation and experimental data. The melt pool was sustained within the range of high temperature and the concrete ablation occurred continuously. The gas generation and aerosol release were under the influence of melt temperature and overlying water pool, respectively.

• Journal of the Korean Society of Safety
• /
• v.33 no.6
• /
• pp.8-14
• /
• 2018

Recently, serious problems occurred such as insecticide eggs, sanitary pads with carcinogens, radon(Rn) emitting beds in domestic. It had not been establishing the inspection system to evaluate safety and human harmfulness before occurring real accidents. This research was conducted to test preliminary experimental inspection for consideration of safety insensibility. The influence of corrosion of metals and plants was studied through aerosol type spraying of agricultural pesticide products coming into the market. These products contain primary three insecticide ingredients(Flufenoxuron, Etoxazole, Fipronil) in recent accidents. Visual examination, SEM-EDS and optical microscope were used for the analysis for corrosion effect. Results show that a lot of ingredients contain in the crop protection products, and various type of corrosion exist in the surface of metals and plants. Therefore, it is necessary to provide health warning and accurate range of use for crop protection products containing insecticide ingredients.

• Nuclear Engineering and Technology
• /
• v.55 no.3
• /
• pp.989-998
• /
• 2023

Under nuclear reactor severe accidents, the resuspension of radioactive aerosol may occur in the containment due to the disturbing airflow generated by hydrogen combustion, hydrogen explosion and containment depressurization resulting in the increase of radioactive source term in the containment. In this paper, for containment conditions, by considering the contact between particle and rough deposition surface, the distribution of the distance between two contact points of particle and deposition surface, rolling and lifting separation mechanism, resuspension model based on random contact with rough surface (RRCR) is established. Subsequently, the detailed torque and force analysis is carried out, which indicates that particles are more easily resuspended by rolling under low disturbing airflow velocity. The simulation result is compared with the experimental result and the prediction of different simulation methods, the RRCR model shows equivalent and better predictive ability, which can be applicable for simulation of aerosol resuspension in containment during severe accident.

• Environmental Engineering Research
• /
• v.22 no.2
• /
• pp.216-223
• /
• 2017

For the prediction of the ventilation rate for removing the non-isothermal concentrated fume from the semi-enclosed space, the computational fluid dynamics (CFD) analysis was done. Securing the proper ventilation conditions in emergency state such as in fire is crucial factor for the protection of the resident in the space. In the analysis for the determining the proper ventilation rate, the experimental study had the limitation for simulating the versatile conditions of fume development. The theoretical and computational method had been chosen as the alternate tool for the experimental analysis. In this study, the CFD analysis was done on the defined model which already had been done the experimental analysis by the previous workers. By comparing the prediction on the plume heights and the ventilation rates by the CFD analysis at, and in the parametric model of $1m^3$ with those of the previous experimental works, the feasibility of the computational analysis was evaluated. For the required ventilation rate analyzed by the CFD analysis was over predicted in 7.1% difference with that of the experimental results depending on the different plume height. With the comparison with the analytical Zukoski model at, the CFD analysis on the ventilation was under predicted in 8.3%. By the verification of the feasibility of the CFD analysis, the extended analysis was done for getting the extra information such as the water vapor distribution and $CO^2$ distribution in the semi-enclosed spaces.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2019.10a
• /
• pp.87-87
• /
• 2019

• Korean Journal of Remote Sensing
• /
• v.30 no.5
• /
• pp.627-639
• /
• 2014

Accurate correction of surface effect from back scattered solar radiance is one of key issue to retrieve aerosol information from satellite measurements. In this study, two different methods are applied to retrieve surface reflectance by using single visible channel measurement from meteorological imager onboard COMS. The first one is minimum reflectance method, which composes the minimum value among previously measured reflectances at each pixel over a certain search window length. This method assumes that the darkest pixel corresponds to the aerosol-free condition, and deduces surface reflectance by correcting atmospheric scattering from the measured visible reflectance. The second method, named as the "atmospheric correction method" in this study, estimates the result by correcting aerosol and atmospheric scattering with ground-based observation of aerosol optical properties. The purpose of this study is to investigate the retrieval accuracy of the widelyused minimum reflectance method. Also, the retrieval error caused by the loading of background aerosol is mainly estimated. The comparison between surface reflectances retrieved from the two methods shows good agreement with the correlation coefficient of 0.87. However, the results from the minimum reflectance method are slightly overestimated than the values from the atmospheric correction method when surface reflectance is lower than 0.2. The average difference between the two results is 0.012 without the background aerosol correction. By considering the background aerosol effect, however, the difference is reduced to 0.010.

• Asian Journal of Atmospheric Environment
• /
• v.5 no.2
• /
• pp.79-85
• /
• 2011

The purpose of this study is to evaluate the strength of the near-UV wavelength of 380 nm relative to visible and near-IR bands, and to find the suitable wavelength for detecting aerosols by using the Global Imager (GLI) sensor aboard the Advanced Earth Observing Satellite-II (ADEOS-II). Sensitivity analysis is performed for the retrieval of biomass burning aerosols by employing the radiative transfer model Rstar5b. It is determined that background surface reflectance in the blue band is similar to that in the near-UV band, and that wavelengths in the blue bands are more sensitive to the Aerosol Optical Thickness (AOT) than wavelengths in the near-UV band. The Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) is used in the indirect method used for aerosol retrieval, and the wavelength pair 380 nm and 460 nm is determined to be the most sensitive to the AOT. The results of this study suggest that wavelengths in the blue bands are suitable for detecting biomass burning aerosols over the Korean peninsula.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1306-1311
• /
• 2009

In recent semiconductor manufacturing clean rooms, in order to improve clean room air quality, air washers are used to remove airborne gaseous contaminants such as $NH_3$, SOx and organic gases from the outdoor air introduced into clean room. Meanwhile, there is a large amount of exhaust air from a clean room. From an energy conservation point of view, heat recovery is therefore useful for reducing the outdoor air conditioning load for a clean room. Therefore it is desirable to recover heat from the exhaust air and use it to reheat the outdoor air. In the present study, numerical analysis and experiment was conducted to simulate the amount of energy reduction of exhaust air heat recovery type air washer system. The present numerical results showed good agreement with the results of the experimental data.