• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.334-338
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• 2008

As open skies polices have permeated all over the world, Korea's basic direction of aviation policy is promoting the benefit of the public and the national carriers' competitive power by establishing open skies agreements between the countries. The open skies' directions should be promoted by considering the relationships of various attributes such as governments, airlines, and passengers. To decide the right directions of open skies, we should investigate the economic effects of open skies policies. This research develops a simulation model to analyze the dynamic characteristics of open skies. By using the developed model, this research analyzes the economic effects of open skies.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.8
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• pp.82-90
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• 2019

We propose an equivalent model of a sintered metal mesh filter calculated by Ergun's equation and polynomial regression for the CFD analysis of breakaway devices at a hydrogen fueling station. CFD analysis of filters that cause high pressure loss is essential because breakaway devices in high-pressure hydrogen conditions require low pressure loss. A differential pressure experiment with a filter was performed in a low-pressure air condition considering similarities. An equivalent model was developed by deriving the resistance value by the polynomial regression using the experimental results. The results of CFD analysis using the equivalent model show that there was almost no error in the operating condition of the breakaway device compared to the experimental results. Through this work, we believe that the proposed equivalent model of a filter can be applied to the analysis of breakaway devices in hydrogen fueling stations. We will study how to optimize the shape and position of the filter in breakaway devices using the developed equivalent model.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.89-96
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• 2005

This study has been performed on the mechanism of heat transfer between stratospheric airship and its surroundings while the airship is staying in the air at the altitude of 20km. The computational grid of airship has been generated and the results influenced by the number and the shape of grids have been compared. The temperature distributions have been obtained through this thermal analysis considering three modes of heat transfer - conduction, convection and radiation - in stratospheric conditions. Based on the airship's surface and inner temperature variations, the influence of temperature distributions on the helium envelope and the payload has been predicted.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.31-39
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• 2011

The flowfield in a solid rocket motor was simulated at the wall-injection test model, which has a fin-slot grain and submerged nozzle, and visualized by a smoke-wire. The high speed CCD camera captured the visualized images around the nozzle inlet through the grain center port. The vortical tube structure and circumferential flow patterns at the nozzle throat were visualized. The radial momentum transfer caused by the shear-interactions of slot-outlet flow, fin-base flow and grain port flow from upstream worked as the source of these phenomena.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.19-27
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• 2018

In this study, a numerical study was conducted to characterize the E-D nozzle which changes according to the nozzle pressure ratios. Three different numerical analysis models were designed by changing the pintle inflection angles. When the nozzle pressure ratio is low, the outside air flows into the E-D nozzle to form an open flow field. As the nozzle pressure ratio increases, the flow transition occurs to become the closed flow field where the recirculation region is isolated inside the nozzle. Also, the highest thrust coefficient was obtained in the analytical model with high pintle inflection angle at all nozzle pressure ratios.

• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.134-153
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• 2015

When making urban planning, it is important to understand climate effect caused by urban structural changes. Seoul city applies UPIS(Urban Plan Information System) which provides information on urban planning scenario. Technology for analyzing climate effect resulted from urban planning needs to developed by linking urban planning scenario provided by UPIS and climate analysis model, CAS(Climate Analysis Seoul). CAS develops for analyzing urban climate conditions to provide realistic information considering local air temperature and wind flows. Quantitative analyses conducted by CAS for the production, transportation, and stagnation of cold air, wind flow and thermal conditions by incorporating GIS analysis on land cover and elevation and meteorological analysis from MetPhoMod(Meteorology and atmospheric Photochemistry Meso-scale model). In order to reflect land cover and elevation of the latest information, CAS used to highly accurate raster data (1m) sourced from LiDAR survey and KOMPSAT-2(KOrea Multi-Purpose SATellite) satellite image(4m). For more realistic representation of land surface characteristic, DSM(Digital Surface Model) and DTM(Digital Terrain Model) data used as an input data for CFD(Computational Fluid Dynamics) model. Eight inflow directions considered to investigate the change of flow pattern, wind speed according to reconstruction and change of thermal environment by connecting green area formation. Also, MetPhoMod in CAS data used to consider realistic weather condition. The result show that wind corridors change due to reconstruction. As a whole surface temperature around target area decreases due to connecting green area formation. CFD model coupled with CAS is possible to evaluate the wind corridor and heat environment before/after reconstruction and connecting green area formation. In This study, analysis of climate impact before and after created the green area, which is part of 'Connecting green network across the north and south in Seoul' plan, one of the '2020 Seoul master plan'.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.488-496
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• 2017

Emissions of pollutants from ship-based sources are controlled by the International Maritime Organization (IMO). Since pollutants emitted from ship may be dispersed to the land, controlling emissions from ships is necessary for efficient air quality management in Incheon, where exposure to ship-based pollution is frequent. It has been noted that the ratios of air pollutant emissions from coastal areas to inland areas are about 14% for NOx and 10% for SOx. The air quality of coastal urban areas is influenced by the number of ships present and the dispersion pattern of the pollutants released depending on the local circulation system. In this study, the dispersion of pollutants from ship-based sources was analyzed using the numerical California Puff Model (CALPUFF) based on a meteorological field established using the Weather Research and Forecasting Model (WRF). Air pollutant dispersion modeling around coastal urban regions such as Incheon should consider point and line sources emitted from both anchored and running ships, respectively. The total average NOx emissions from 82-84 ships were 6.2 g/s and 6.8 g/s, entering and leaving, respectively. The total average SOx emissions from 82-84 ships, entering and leaving, were 3.6 g/s and 5.1 g/s, respectively. The total average emissions for NOx and SOx from anchored ships were 0.77 g/s and 1.93 g/s, respectively. Due to the influence of breezes from over land, the transport of pollutants from Incheon Port to inland areas was suppressed, and the concentration of NOx and SOx inland were temporarily reduced. NOx and SOx were diffused inland by the sea breeze, and the concentration of NOx and SOx gradually increased inland. The concentration of pollutants in the area adjacent to Incheon Port was more influenced by anchored ship in the port than sea breezes. We expect this study to be useful for setting emission standards and devising air quality policies in coastal urban regions.

• Journal of the Korean earth science society
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• v.25 no.6
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• pp.418-427
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• 2004

Recently, urban planning with consideration of urban climate, represented by the concept of urban ventilation lane is widely practiced in many countries. The concept of urban ventilation lane is mainly aimed to improve the thermal comfort within urban area in summer season. It has also the aim to reduce the urban air pollution by natural cold air drainage flows which are to be intensified by a suitable alignment of buildings as well as use zonings based on scientific reasons. In this study, the prevailing wind ventilation lane of a local wind circulation and around Daegu for a typical summer days was investigated by using a numerical simulation. The transport of air pollutants by the local circulation winds was also investigated by using the numerical simulation model, the RAMS (Reasonal Atmospheric Model System).The domain of interest is the vicinity of Daegu metropolitan city (about 900 km2). The horizontal scale of the area is about 30 km. The simulations were conducted under a late spring synoptic condition with weak gradient wind and almost clear sky. From the numerical experiment, the following three conclusions were obtained: (1) The major wind passages of the local circulation wind generated by radiative cooling over the representative mountains of Daegu (Mt. Palgong and Mt. Ap) were found. The winds blow down along the valley axis over the eastern part of Daegu as a gravity flow during nighttime. (2) At the flatland, the winds blow toward the western part of Daegu through the city center. (3) As the results, the air pollutants were transported toward the western part of Daegu by the winds during nighttime.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.439-454
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• 2008

The purpose of this study was to extensively identify $PM_{10}$ sources and to estimate their contributions to the study area, based on the analysis of the $PM_{10}$ mass concentration and the associated inorganic elements, ions, and total carbon. The contribution of $PM_{10}$ sources was estimated by applying a receptor method because identifying air emission sources were effective way to control the ambient air quality. $PM_{10}$ particles were collected from May to November 2007 in the Yongin-Suwon bordering area. $PM_{10}$ samples were collected on quartz filters by a $PM_{10}$ high-volume air sampler. The inorganic elements (Al, Mn, V, Cr, Fe, Ni, Cu, Zn, Cd, Pb, Si, Ba, Ti and Ag) were analyzed by an ICP-AES after proper pre-treatments of each sample. The ionic components of these $PM_{10}$ samples ($Cl^_$, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $NH_4^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) were analyzed by an IC. The carbon components (OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3) were also analyzed by DRI/OGC analyzer. Source apportionment of $PM_{10}$ was performed using a positive matrix factorization (PMF) model. After performing PMF modeling, a total of 8 sources were identified and their contribution were estimated. Contributions from each emission source were as follows: 13.8% from oil combustion and industrial related source, 25.4% from soil source, 22.1% from secondary sulfate, 12.3% from secondary nitrate, 17.7% from auto emission including diesel (12.1%) and gasoline (5.6%), 3.1% from waste incineration and 5.6% from Na-rich source. This study provides information on the major sources affecting air quality in the receptor site, and therefore it will help us maintain and manage the ambient air quality in the Yongin-Suwon bordering area by establishing reliable control strategies for the related sources.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.4
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• pp.878-885
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• 2008

The FPDs(Flat Panel Displays) such as LCD(Liquid Crystal Display) and PDP(Plasma Display Panel) and OLED(Organic Light Emitting Diode), recently, have been substituted for CRT(Cathode Ray Tube) displays because they have a convex surface, small volume, light weight and lower electric power consumption. The productivity of FPDs is greatly dependent on the area of thin glass panel with 0.6 - 0.8mm thickness because FPDs are manufactured by cutting a large-scaled thin glass panel with patterns to the required product dimensions. So FPD's industries are trying to increase the area of thin glass panel. For example, the thin glass panel size of the 8th generation is 2,200mm in width, 2,600mm in length and 0.7mm in thickness. The air flows both in the thin glass panel and in the porous PE-plate surface were modeled and analyzed, from which a working condition was estimated. The thin glass panel on the porous PE-plate surface with self-lubricating characteristics was investigated and compared with that on the square duct floating bar surface with many holes of 1mm diameter when the thin glass panel contacts the floating bar surface due to malfunction of electric power supply.