• Journal of Environmental Science International
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• v.18 no.9
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• pp.941-952
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• 2009

The urban microscale wind field around the air quality monitoring station was investigated in order to check how a building complex influences it. For this study as the high density areas Jwa-dong and Yeonsan-dong monitoring sites in Busan were chosen. As the direction of inflow which is perpendicular to the building of the monitoring station was expected to cause the considerable variation of the wind field, that direction was selected. The model Envi-met was used as the diagnostic numerical model for this study. It is suitable for this investigation because Envi-met has the microscale resolution. After simulating it, on the leeward side around a building complex the decrease of flow velocity and some of vortexes or circulation area were discovered. In addition, on the edge of the top at the building and at the back of the building the upward flow was developed. If the sampling hole of monitoring site were located in this upward flow, it would be under the influence of upward flow from the near street.

• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.60-67
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• 2014

In this study, four methods for calculation of continuous daily flow was suggested using short-term or partial recording station of streamflow including missing data. Using these methods, standard flows at the outlet of unit/small basins for the management of total maximum daily loads (TMDLs) in Namgang dam basin were estimated from full-period flow duration curve (FDC). Four methods of extension are described, and their properties are explored. The methods are regression (REG), regression plus noise (RPN), and maintenance of variance extension types 1 and 2 (MOVE.1, MOVE.2). In these methods, the continuous daily flow was calculated using extension equation based on correlation analysis, after conducting the correlation analysis between historic record of streamflow and long-term recording station (a base station). Finally the best optimal method was selected as the MOVE.2, and the standard flows in the abundant, ordinary, low and drought flow estimated from FDC was evaluated using MOVE.2 in unit/small basins.

• Environmental Engineering Research
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• v.25 no.3
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• pp.374-383
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• 2020

Landfill gas (LFG) emissions from a given amount of landfill waste depend on the carbon flows in the waste. The objective of this study was to more accurately estimate the first-order decay parameters through methane (CH₄) and carbon flow balances based on the analysis of a full-scale landfill with long-term data and detailed field records on LFG and leachate. The carbon storage factor for the case-study landfill was 0.055 g-degradable organic carbon (DOC) stored per g-wet waste and the amounts of DOC lost with the leachate were less than 1.3%. The appropriate CH₄ generation rate constant (k) for bulk waste was 0.24 y-1. The the CH₄ generation potential (L0) values ranged 33.7-46.7 m3-CH₄ Mg-1, based on the fraction of DOC that can decompose (DOCf) value of 0.40. Results show that CH4 and carbon flow balance methods can be used to estimate model parameters appropriately and to predict long-term carbon emissions from landfills.

• Journal of Korea Water Resources Association
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• v.33 no.6
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• pp.671-679
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• 2000

Regionalization technique using flow duration curve and spatial interpolation algorithm is developed for the purpose of estimating daily flow time series at ungauged station. In this study, we assumed a part of 8 gauging stations of Nakdong River basin as ungauged stations. Then, we generated flow duration curves and daily flow hydrographs by regionalization technique at ungauged stations. And we compared generated and observed hydrographs. The simulation results showed that the observed flows were well simulated by the proposed method and that the general patterns of the observed flows were satisfactorily reproduced by the regionalization technique. From these results, it is possible that we obtain daily flow information without application of labour intensive and time consuming deterministic models, which require complicating quantification of model parameter values. And we compared the regionalization techniques with the specific discharge method which is the most general approach in hydrological practice in Korea. The results showed that the regionalization technique was superior to specific discharge method.method.

• Journal of the Korean Geotechnical Society
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• v.31 no.12
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• pp.45-57
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• 2015

This paper presents the application of the Coupled Eulerian-Lagrangian (CEL) technique to simulate the debris flow. The main objective of this study is to investigate the applicability of CEL technique to the behavior of debris flow, such as flow velocity and influence area. Comprehensive studies to verify the behavior of debris flow are presented in this study. Through comparison with measured flow velocity from Umyeonsan (Mt.), CEL approach was found to be in good agreement with the general trend observed by in actual debris flow. In addition, CEL technique accurately simulated the behavior of debris flows, therefore, it can be used for designing the countermeasure structure.

• Ocean and Polar Research
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• v.36 no.4
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• pp.475-485
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• 2014

Seawater flow characteristics around a manganese nodule mining device in deep sea were analyzed through numerical investigation. The mining device influences the seawater flow field with complicated velocity distributions, and they are largely dependent on the seawater flow speed, device moving speed, and injection velocity from the collecting part. The flow velocity and turbulent kinetic energy distributions are compared at several positions from the device rear, side, and top, and it is possible to predict the distance from which the mining device affects the seawater flow field through the variation of turbulent kinetic energy. With the operation of the collecting device the turbulent kinetic energy remarkably increases, and it gradually decreases along the seawater flow direction. Turbulent kinetic energy behind the mining system increases with the seawater flow velocity. The transient behavior of nodule particles, which are not collected, is also predicted. This study will be helpful in creating an optimal design for a manganese nodule collecting device that can operate efficiently and which is eco-friendly.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.448-452
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• 2004

Instream flow is necessary to manage the basic function of the rivers. The evaluation method of instream flow in a big river has been studied widely. However, the study in a urban hasn't researched. In theses days the environmental function of a river becomes very important. The evaluation method and secure of instream flow are basic conditions to perform it. Especially view of stream, recreation, protection of ecology are highly demanded In a urban according to the multipurpose of river spaces. In this paper the evaluation methods of instream flow were compared and investigated with many papers. This paper presents a proper evaluation procedure of instream flow in a urban stream through comparison and examination. According to the demanded hydraulic conditions the method can be considered the environmental function depend on the purpose of river restoration. The relationship of the coefficient of roughness and the slope of the river bed were examinated in order to estimate the minimum instream flow corresponding to proper Hydraulic conditions. Also calculate the instream flow of Sueng-gi stream in In-cheon.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.407-419
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• 2016

The low flow is the necessary and important index to establish national water planning, however there are lots of uncertainty in the low flow estimation. Therefore, the objectives of this study are to assess the climate change uncertainty and the effects of hydrological models on low flow estimation. The 5 RCMs (HadGEM3-RA, RegCM4, MM5, WRF, and RSM), 5 statistical post-processing methods and 2 hydrological models were applied for evaluation. The study area were selected as Chungju dam and Soyang river dam basin, and the 30 days minimum flow is used for the low flow evaluation. The results of the uncertainty analysis showed that the hydrological model was the largest source of uncertainty about 41.5% in the low flow projection. The uncertainty of hydrological model is higher than the other steps (RCM, statistical post-processing). Also, VIC model is more sensitive for climate change compared to SWAT model. Therefore, the hydrological model should be thoroughly reviewed for the climate change impact assessment on low flow.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3144-3149
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• 2007

A numerical analysis for temperature distribution of four different materials such as iron, silicon, aluminum and PVC has been performed in this study to predict thermal behaviors of combined weapon systems in a large environmental tester. Thus, experimental conditions have been proposed using a calculating software (SolidWorks 2007 COSMOS FloWorks) to prepare for field tests and analyze heat flow inside the environmental tester and temperature distributions of materials. The boundary conditions of the analysis are composed of inlet and outlet conditions of the environmental tester with different pressures and the limit of low temperature of -30$^{\circ}C$. The soaking time of the system in the environmental tester has been calculated by this commercial program in this study to carry out the experiment.

• Journal of Environmental Science International
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• v.24 no.12
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• pp.1691-1703
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• 2015

When constructing tunnels, it is important to understand structural, geological and hydrogeological conditions. Geumgeong tunnel that has been constructed in Mt. Geumjeong for the Gyeongbu express railway induced rapid drawdown of groundwater in the tunnel construction area and surroundings. This study aimed to analyze groundwater flow system and baseflow using long-term monitoring and groundwater flow modeling around Geumgeong tunnel. Field hydraulic tests were carried out in order to estimate hydraulic conductivity, transmissivity, and storativity in the study area. Following the formula of Turc and groundwater flow modeling, the annual evapotranspiration and recharge rate including baseflow were estimated as 48% and 23% compared to annual precipitation, respectively. According to the transient modeling for 12 years after tunnel excavation, baseflow was estimated as $9,796-9,402m^3/day$ with a decreasing tendency.