• Journal of Environmental Science International
• /
• v.12 no.9
• /
• pp.977-986
• /
• 2003

In this study, the scenario for a numerical modeling of the fine grid scale air dispersion phenomena was proposed and an analysis of the special event which was occurred on September 3, 2002 was performed using by a coarse grid prognostic meteorological model, a fine grid diagnostic meteorological model and a fine grid air dispersion model. Based on the results, we found that the local circulations, like as land-sea breeze, should be seriously considered for evaluating the high PM10 concentration event and for making the reduction policy of the major air pollutant emissions in Ansan area.

• Journal of Environmental Science International
• /
• v.24 no.6
• /
• pp.827-840
• /
• 2015

This study analyzed a correlation between South China Sea summer (June to September) monsoon (SCSSM) and the ENSO for the last 32 years (1979 to 2010). There was a correlation that the higher (lower) the SST in the $Ni{\tilde{n}}o-3.4$ region was, the weaker (stronger) the SCSSM intensity was. To identify the reason for this correlation, a difference of means between 8 El $Ni{\tilde{n}}o$ years and 8 La $Ni{\tilde{n}}a$ years (June to September). The analysis on the difference between two groups with respect to the 850 hPa stream flows showed that there were anomalous huge cyclones in the subtropical Pacific in the both hemispheres so that cold and dry anomalous northerlies were strengthened in the South China Sea relatively while anomalous westerlies were strengthened from the Maritime Continent to the off the coast of Chile. The analysis on the difference between two groups with respect to the 200 hPa stream flows showed that the opposite anomalous pressure system pattern to that in the 850 hPa stream flows were shown. In the subtropical Pacific of the both hemispheres, anomalous anticyclones existed so that anomalous easterlies were strengthened from the Maritime Continent to the equatorial central Pacific. Considering the anomalous atmospheric circulations in the upper and lower layers of the troposphere, upward airflows from the equatorial central and eastern Pacific were downward in the South China Sea and the Maritime Continent, which was a structure of anomalous atmospheric circulations. This means that the Walker Circulation was weakened and it was a typical structure of atmospheric circulations revealed in El $Ni{\tilde{n}}o$ years.

• Journal of the Korean earth science society
• /
• v.38 no.1
• /
• pp.35-48
• /
• 2017

This study analyzed the obvious increasing tendency of summer (June to August) rainfall in the region of Korea- and northern China ($35^{\circ}-40^{\circ}N$, $110^{\circ}-130^{\circ}E$) in the late 1990s. In order to investigate the causes of the increase in summer rainfall since 1998, we analyzed the difference of the rainfall average between 1998-2012 and 1981-1997. The analysis of the 850 hPa stream flows showed that the huge anomalous anticyclonic circulations were developed in North Pacific and eastern Australia. In both hemispheres, the anomalous easterlies (anomalous trade winds) were strengthened from the equatorial central Pacific to the tropical western Pacific by the anomalous circulations, which was an anomalous circulation pattern shown in La $Ni{\tilde{n}}a$ years. As for the 200 hPa stream flows, the huge anomalous cyclonic circulations were also developed in both South Pacific and North Pacific. These two anomalous circulations reinforced the anomalous westerlies in the equatorial central and western Pacific, leading to the increase in summer rainfall in the region of Korea- and northern China since the late 1990s in association with La $Ni{\tilde{n}}a$ pattern, which was resulted in strengthening the Walker circulation. Recently in East Asia, the local Hadley circulation has been strengthened in which upward flows in the equatorial western Pacific and mid-latitude region of East Asia have descended in the subtropical western Pacific.

• Journal of Environmental Science International
• /
• v.15 no.12
• /
• pp.1141-1154
• /
• 2006

Orographic effect is one of the important factors to induce Local circulations and to make atmospheric turbulence, so it is necessary to use the exact topographic data for prediction of local circulations. In order to clarify the sensitivity of the spatial resolution of topography data, numerical simulations using several topography data with different spatial resolution are carried out under stable and unstable synoptic conditions. The results are as follows: 1) Influence of topographic data resolution on local circulation tends to be stronger at simulation with fine grid than that with coarse grid. 2) The hight of mountains in numerical model become mote reasonable with high resolution topographic data, so the orographic effect is also emphasized and clarified when the topographic data resolution is higher. 2) The higher the topographic resolution is, the stronger the mountain effect is. When used topographic data resolution become fine, topography in numerical model becomes closer to real topography. 3) The topographic effect tends to be stronger when atmospheric stability is strong stable. 4) Although spatial resolution of topographic data is not fundamental factor for dramatic improvement of weather prediction accuracy, some influence on small scale circulation can be recognized, especially in fluid dynamic simulation.

• Journal of Environmental Science International
• /
• v.3 no.1
• /
• pp.39-47
• /
• 1994

Dispersion characteristics of air pollutants in the mountainous coastal area are investigated in considering with the mesoscale local circulations using a two dimensional numerical model with two kinds of topograpy of 500m and 300m. In the model, land-sea breezes and mountain-valley wind are mainly considered under the condition of the absence of large scale prevailing flow in the circulation analysis, and the pollutants dispersion is traced by the Lagrangian methods. According to the results, the wind velocity is affected by topography and is stronger in the case of 500m height mountain than that of 300m, the Pollutants that source is near the coast transported over the mountain and dispersed to behind inland area. It is classified that the topography change control affects the wind velocity and the circulations. The pollutants that source is different transported and concentrated to behind inland and/or diffused to the sea area by the combination of the wind system with topographic changes. The results can be applied to the air pollution control with the arrangement design of industrial area and the planning of coastal developments.

• Korean Institute of Interior Design Journal
• /
• v.20 no.3
• /
• pp.3-12
• /
• 2011

The purpose of this study is to analyse the diagrammatic design approaches and programmatic design approaches in contemporary architecture, so that this reveals the sequential systems of circulation in the space and liberal movement of the visitors in the buildings of those diagrammatic and programmatic architecture. Contemporary architecture generates the new forms and meanings through the dynamic visions and perspectives. Such a variation of sequential vistas and dynamic visions produce a perception of time and a potential movements of axis in the perspective. This study give the systematic body to the relations among visions, movements, sequences, forms, circulations and time. Diagrammatic and programmatic design approaches show the heterogeneous spaces and the informal architectures in contemporary architecture. Therefore, movements of various view points, differrentiations of objects in the perspectives, and multiple view frames appears in the designs of initiative architects. In conclusion, this study systemizes the concepts of time, sequential movements, and perceptions of events in contemporary architecture through the analyse of 18 architectural works of important architects in 2000s. And this shows details of the transitional movement of space and the perception of time in contemporary Architecture. The Being of the active time constructs formal transformations, spacial differentiations, accumulations of human behaviors, and movements of circulations involved with experiences of the field of senses. Therefore, Zeitlichkeit is perceived through concepts of the sequences of those spaces, forms, behaviors, and memories.

• Atmosphere
• /
• v.22 no.3
• /
• pp.331-344
• /
• 2012

The changes in the Hadley circulation during the second half of the 20th century were examined using observations and the 20C3M (Twentieth Century Climate in Coupled Models) simulations by the 21 IPCC AR4 models. Multi-model ensemble (MME) mean shows that the mean features of the Hadley circulation, such as the intensity, magnitude, and the seasonal variations, are very realistically reproduced, compared to the ERA40 reanalysis. But the long-term trends of the Hadley circulation in 20C3M MME are quite different to those of observations. The observed intensity of the Hadley cell is persistently enhanced, particularly during boreal winter. In comparison, the meridional overturning circulations reproduced in the MME mean remains invariant in time, and even weakened in boreal summer. This discrepancy between the ERA40 and 20C3M MME is consistently shown in the overall structure of the Hadley circulations, such as mass streamfunction, the velocity potential, the vertical shear of meridional wind, and the vertical velocity in the tropical region. This results indicate that the current climate models are skill-less to capture the long-term trend of Hadley circulation yet, and should be improved in simulation of the large-scale features to enhance the confidence level of future climate change projection.

• Land and Housing Review
• /
• v.11 no.3
• /
• pp.39-48
• /
• 2020

Gamcheon village was a poor village in the past, but it recently has boomed as a representative tourists' attraction in the region. Its unique topography and history have played a significant role in the town's growth as a famous tourists' attraction. The factors contributed decisively to the formation of a special spatial structure there. In the process of the town's rapid development as a tourists' destination, however, the tourism overflowed. As such, the interests of the residents and the tourists conflicted, and the segregation between the two has augmented. These gaps seem to have enormously distorted the perception of the spaces as much as they have seriously distracted the existing traffic circulations in the village. The purpose of this study is to identify the differences in spatial perception of both residents and tourists in the Gamcheon village. For the purpose, it assumes the residents' natural movements and the tourists' purposeful movements, and they are analyzed by the space syntax. The major findings are that the circulations of the residents and the tourists in the village are clearly separated and that the two groups perceive the same space completely differently. This confirms the fact that even the same space could be recognized and used in a totally different way depending on the users' purposes.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4759-4775
• /
• 2022

The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

• Nuclear Engineering and Technology
• /
• v.56 no.2
• /
• pp.611-623
• /
• 2024

The ISP-47 TOSQAN experiment was analyzed with containmentFOAM which is an open-source CFD code based on OpenFOAM. The containment phenomena taking place during the experiment are gas mixing, stratification and wall condensation in a mixture composed of steam and non-condensable gas. The k-ω SST turbulence model was adopted with buoyancy turbulence models. The wall condensation model used is based on the diffusion layer approach. We have simulated the full TOSQAN experiment which had a duration 20000 s. Sensitivity studies were conducted for the buoyancy turbulence models with SGDH and GGDH and there were not significant differences. All the main features of the experiments namely pressure history, temperature, velocity and gas species evolution were well predicted by containemntFOAM. The simulation results confirmed the formation of two large flow stream circulations and a mixing zone resulting by the combined effects of the condensation flow and natural convection flow. It was found that the natural convection in lower region of the vessel devotes to maintain two large circulations and to be varied the height of the mixing zone as result of sensitivity analysis of non-condensing wall temperature. The computational results obtained with the 2D mesh grid approach were comparable to the experimental results.