• 한국대기환경학회지
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• 제23권4호
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• pp.449-456
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• 2007

Dispersion coefficient preprocessing schemes have been examined to improve plume dispersion model performance in complex coastal areas. The performances of various schemes for constructing the sigma correction order were evaluated through estimations of statistical measures, such as bias, gross error, R, FB, NMSE, within FAC2, MG, VG, IOA, UAPC and MRE. This was undertaken for the results of dispersion modeling, which applied each scheme. Environmental factors such as sampling time, surface roughness, plume rising, plume height and terrain rolling were considered in this study. Gaussian plume dispersion model was used to calculate 1 hr $SO_2$ concentration 4 km downwind from a power plant in Boryeung coastal area. Here, measured data for January to December of 2002 were obtained so that modelling results could be compared. To compare the performances between various schemes, integrated scores of statistical measures were obtained by giving weights for each measure and then summing each score. This was done because each statistical measure has its own function and criteria; as a result, no measure can be taken as a sole index indicative of the performance level for each modeling scheme. The best preprocessing scheme was discerned using the step-wise method. The most significant factor influencing the magnitude of real dispersion coefficients appeared to be sampling time. A second significant factor appeared to be surface roughness, with the rolling terrain being the least significant for elevated sources in a gently rolling terrain. The best sequence of correcting the sigma from P-G scheme was found to be the combination of (1) sampling time, (2) surface roughness, (3) plume rising, (4) plume height, and (5) terrain rolling.

• 한국항행학회논문지
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• 제3권2호
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• pp.97-107
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• 1999

항공기의 착륙을 추적하기 위해 많이 사용되는 수동 센서인 레이저 거리 측정기(LRF)와 전방관측 적외선 카메라(FLIR)는 배기가스교란(Exhaust Plume Disturbance)으로 인한 고도각 측정 시에 오차를 발생시킨다. 이 경우에 확장형 칼만필터(EKF)를 사용하여 거리 및 고도를 측정하면 배기가스(plume)와 같은 비-가우시안 잡음 때문에 추적 성능이 저하된다. 본 논문에서는 배기가스의 발생 타이밍을 검출기(PD)를 사용하여 확인한 후에 배기가스가 발생하면 적응형 추산법을 사용하고 배기가스의 영향이 없을 때에는 기존의 확장형 칼만필터를 사용하는 복합 방식을 제안하고 이를 위한 적응형 필터를 설계한다. 이 혼합형 필터는 배기가스와 같은 미지의 바이어스를 제거하는데 매우 효과적인 방법이며 시뮬레이션을 통하여 이러한 성능을 예증한다.

• Journal of Radiation Protection and Research
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• 제23권4호
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• pp.251-257
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• 1998

국내 원전에 적용하기 위한 기체 방사성 물질 확산 및 피폭 평가 코드를 개발하였다. 정상 운전에 의한 기체 방사성 물질 확산 및 피폭 평가에는 직선 궤도 가우시안 플륨 모델을 사용하는 XOQDOQ 코드가 사용되어 왔다. 본 연구에서는 이 코드의 단점인 발전소 주변 지역에서의 바람 방향의 영향, 산악 지형에 대한 모델, 습식 침적에 대한 개선이 이루어졌다. 현실적인 유효 고도 보정 및 산악 침투 모델을 통해서 산악 지형에 대한 고려를 하였고, 바람 발생 확률 빈도를 수정하여 직선 궤도 모델을 보완하였다. 개발된 코드는 영광원전의 주민피폭선량평가를 위해 채택되었으며, 산악이 많은 우리 나라 다른 발전소에 적용하기 위해 산악지형 입력변경을 통하여 적절히 사용될 수 있을 것이다.

• 한국대기환경학회지
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• 제14권2호
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• pp.81-94
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• 1998

Six complex terrain dispersion models recommended by the U. S. Environmental Protection Agency were investigated using a hypothetical case in which a plume approaches complex terrain. The six models considered were Valley, CTSCREEN, COMPLEX 1, SHORTZ, RTDM, and CTDMPLUS, the latter four being closely studied. Highest concentrations were predicted for 48 receptors and plume behaviors were compared for stable and unstable meteorological conditions. Under stable conditions, ground-level concentrations were determined by the height of the plume centerline above the terrain. The concentrations estimated by SHORTZ and COMPLEX I were higher than those estimated by CTSCREEN, with CTDMPLUS predicting the lowest concentrations. In particular, the height of the lift midpoint, as well as the co.nterline of the plume, are important in the model calculation of CTDMPLUS. Under unstable conditions, the vertical dispersion plays a key role in determining ground -level concentrations. For this case, concentrations predicted by CTDMPLUS were the 'highest, whereas those predicted by SHORTZ were the lowest. Concentration distributions predicted by CTDMPLUS are quite similar to typical Gaussian distributions even on complex terrain, except for a slight shift of the plume centerline due to the of(tract of the geostrophic wind. In addition,24-hour average concentrations were estimated for comparison with results from the Valley model. Among the four models studied closely, CTDMPLUS predicted the lowest 24-hour average concentrations, but the concentrations estimated by Valley were lower than those estimated by CTDMPLUS.

• Wind and Structures
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• 제27권6호
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• pp.417-430
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• 2018

The concentration fields in the proximities of a local gas emission source are experimentally analyzed in several combinations of wind incidences and source emissions. These conditions are determined by the plume buoyancy, emission velocity and incident flow wind speed. Concentration measurements are performed by an aspirating probe in a boundary layer wind tunnel. The analysis included the mean concentration values and the intensity of concentration fluctuations in a neutral atmospheric boundary layer flow. Different configurations are tested: an isolated stack in a homogeneous terrain and a stack with a bluff body in close proximity, located windward and leeward from the emission source. The experimental mean concentration values are contrasted with Gaussian profiles and the dilution factor is analyzed with respect to the empirical curves of the minimum dilution. Finally, a study on the plume intermittency is performed in a cross-sectional plane near the emission source. It is possible to highlight the following observations: a) plume vertical asymmetry in the case of an isolated emission source, b) significant differences in the dispersion process related to the relative location of the emission source and bluff body effects, and c) different probabilistic behavior of the concentration fluctuation data in a cross-sectional measurement plane inside the plume.

• 한국대기환경학회지
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• 제16권5호
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• pp.539-544
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• 2000

A simple analytic model is proposed here to analyze the concentration deficit field caused by a large area of vegetated area. With non-dimensional deposition velocity chosen as small parameter, the regular perturbation method is exploited to derive the mass balance equation and the dynamic equations for the concentration deficit field, Analytic solutions to those equations are obtained in a closed form for several cases of interest, assuming that the concentration field is stationary and the plume can be nicely approximated as Gaussian for a point source. The results suggest that quite a negligible fraction (less than 1%) of the gaseous air pollutants emitted into the air is removed by the vegetated area of which width is 4 km in wind-wise direction, the typical dimension of the Restricted Development Zones around the metropolitan regions in South Korea.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E4호
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• pp.215-221
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• 2002

The real-time modeling system, named AirWatch System, has been developed to evaluate the environmental impact from a large source. It consists of stack TMS (TeleMetering System) that measures the emission data from the source, AWS (Automatic Weather Station) that monitors the weather data and computer system with the dispersion modeling software. The modeling theories used in the system are Gaussian plume and puff models. The Gaussian plume model is used for the dispersion in the simple terrain with a point meteorological data while the puff model is for the dispersion in complex terrain with three dimensional wind fields. The AirWatch System predicts the impact of the emitted pollutants from the large source on the near-by environment on the real -time base and the alarm is issued to control the emission rate if the calculated concentrations exceed the modeling significance level.

• 대한방사선방어학회:학술대회논문집
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• 대한방사선방어학회 2009년도 춘계 학술발표
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• pp.146-147
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• 2009

• 한국해안해양공학회지
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• 제5권4호
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• pp.302-306
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• 1993

하수제트플룸내에서 플룸과 주변해수와의 밀도차가 Gauss 분포를 나타내고 있다는 가정하에 하구만에 흘러 나오는 하수 플룸의 횡방향 퍼짐속도의 해석해를 구하였다. 이 가정을 도입하므로써 얻는 이점은 첫째, 혼합과정의 결과가 밀도분포에 반영되어 있으므로 이 문제를 다루는데 있어서 혼합과정에 대한 고려를 할 필요가 없다는 점이고, 둘째로는 밀도분포가 알려져 있으므로 그로부터 압력경사력을 구하여 운동방정식에 대입, 문제를 쉽게 풀 수 있다는 점이다. 이론해를 낙동강 하수플룸의 관측결과와 비교해 본 결과, 비교적 잘 일치함을 발견하였고 본 연구의 이론식이 하수플룸의 퍼짐을 다루는데 유용하게 쓰일 수 있음을 확인하였다.

• 한국해안해양공학회지
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• 제5권4호
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• pp.296-301
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• 1993

하수젯트플룸과 주변염수와의 밀도차가 Gauss 분포를 한다는 가정하에 저자들이 구한 플룸의 횡방향 퍼짐에 대한 이론해를 낙동강 하수플룸의 관측자료로 검증하였다. 또한 플룸의 존재가 세립 부유퇴적물의 이동에 미치는 영향도 검토되었다. 현장 관측자료는 이론적인 계산결과와 비교적 잘 맞는 것으로 나타났다. 따라서 본 논문에서 채택하여 검증한 플룸의 횡방향 유동에 대한 이론해가 플룸의 횡방향 퍼짐문제를 다루는데 유용하게 쓰일 수 있을 것이라는 결론을 내릴 수 있었다. 플룸의 존재로 인한 밀도 성충으로 인하여 부유퇴적물은 침전이 지연되고 통상적 정상류의 경우보다 더욱 밀리 운반되는 것으로 생각된다.