• 한국대기환경학회지
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• 제16권4호
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• pp.327-338
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• 2000

complexity in atmospheric environment coupled with shoreline and complex terrain often causes local variations of meteorology that are distinct from those representative over larger surrounding area, These kinds of local variations are less significant in usual long-term environmental impact analyses dealing with continuous plume. The variations could however be crucial in predicting dispersion of toxic substance released in a relatively small area for a short duration. In the present paper the effects of spatial and temporal resolution of diagnostic wind field on the dispersion of the released substance are investigated by using a puff model. A hypothetical release scenario assumes that a substance is released from a location in the Yochon Industrial Estate and passively dispersed within a few-kilometer distance for an hour. The results show that diagnostic analysis could resolve more spatial variations to some extent by employing smaller grid size. The peak concentrations and puff trajectories obtained from spatially -and/or tmeporally -varing diagnostic wind field are found appreciably different from those obtained from uniform wind field. Attention to high-resolution wind field in the both spatial and temporal spaces is called in the consequence analysis of toxic substance release.

• 한국시뮬레이션학회논문지
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• 제16권2호
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• pp.1-8
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• 2007

그리드 컴퓨팅 환경에서 자원 관리는 이기종의 자원들 사이에서 통합과 상호작용을 위해 필수적이다. 이 논문은 자원관리의 복잡한 문제들을 해결하기 위해 집중화된 브로커 기반과 분산화된 브로커 기반 모델링의 자원 관리 기법을 논하고 그리드 컴퓨팅 환경에서 분산화된 브로커 기반 자원 관리 모델링의 설계와 구현을 표현한다. 이 모델은 글로벌 자원 브로커와 로컬 자원 브로커로 이루어지고 우리는 통신의 감소와 로컬 자원 브로커를 사용한 작업 관리의 기능적인 분산을 이끌어낸다. 시뮬레이션 결과는 자원 활용도와 평균 응답 시간의 향상을 보여주고 이 모델이 사용자 요구에 즉각 응답하고 자원의 활용도를 향상시킨다는 것을 증명한다.

• 한국대기환경학회지
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• 제23권4호
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• pp.405-419
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• 2007

A series of tracer experiments for the evaluation of atmospheric dispersion was performed over the urban area of Seoul using two inert, non-deposition perfluorocarbon (PMCH and m-PDCH) gases during three years campaign on 2002, 2003 and 2005. 30 sampling sites for collecting these tracers were located along two arcs of 2.5 and 5 kilometers downwind from the release point. About ten measurements which each lasted for 2 hours or 4 hours were made over the two consecutive days during each campaign. CALPUFF and MM5 meteorological model were applied to evaluate the urban dispersion in detail. Size of Modeling domain was $27\;km{\times}23\;km$ and the fine nest in the modeling domain had a grid size of 0.5 km. The results showed that CALPUFF dispersion model had a tendency to estimate tracer concentrations about $2{\sim}5$ times less than those of ambient samples under many conditions. These consistent inaccuracy in urban dispersion was attributed to inherent inaccuracy and lack of details in terrain data at urban area.

• Journal of Radiation Protection and Research
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• 제48권1호
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• pp.28-43
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• 2023

Background: High-fidelity meteorological data is a prerequisite for the realistic simulation of atmospheric dispersion of radioactive materials near nuclear power plants (NPPs). However, many meteorological models frequently overestimate near-surface wind speeds, failing to represent local meteorological conditions near NPPs. This study presents a new high-resolution (approximately 1 km) meteorological downscaling method for modeling short-range (< 100 km) atmospheric dispersion of accidental NPP plumes. Materials and Methods: Six considerations from literature reviews have been suggested for a new dynamic downscaling method. The dynamic downscaling method is developed based on the Weather Research and Forecasting (WRF) model version 3.6.1, applying high-resolution land-use and topography data. In addition, a new subgrid-scale topographic drag parameterization has been implemented for a realistic representation of the atmospheric surface-layer momentum transfer. Finally, a year-long simulation for the Kori and Wolsong NPPs, located in southeastern coastal areas, has been made for 2016 and evaluated against operational surface meteorological measurements and the NPPs' on-site weather stations. Results and Discussion: The new dynamic downscaling method can represent multiscale atmospheric motions from the synoptic to the boundary-layer scales and produce three-dimensional local meteorological fields near the NPPs with a 1.2 km grid resolution. Comparing the year-long simulation against the measurements showed a salient improvement in simulating near-surface wind fields by reducing the root mean square error of approximately 1 m/s. Furthermore, the improved wind field simulation led to a better agreement in the Eulerian estimate of the local atmospheric dispersion. The new subgrid-scale topographic drag parameterization was essential for improved performance, suggesting the importance of the subgrid-scale momentum interactions in the atmospheric surface layer. Conclusion: A new dynamic downscaling method has been developed to produce high-resolution local meteorological fields around the Kori and Wolsong NPPs, which can be used in short-range atmospheric dispersion modeling near the NPPs.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 추계 학술대회 논문집
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• pp.321-331
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• 2005

과학기술부고시 2003-12호 "원자로시설부지 수문 및 해양특성 조사평가 기준" 이 신규 제정되어, 원전 액체 방사성 유출물에 대한 삼차원적인 해양확산 평가 필요성이 커지고 있다. 한국수력원자력(주)와 전력연구원은 신고리, 신월성, 신울진 원 전등 다수의 신규원전 건설이 계획 또는 추진되고 있는 동해안을 대상으로 광역 및 부지별 입지특성을 반영한 해양확산 평가기술을 개발하고 있다. 동해안의 해수유동은 동해 해수순환에 의해 영향을 받기 때문에 원전 주변의 방사성 물질의 해양확산을 보다 정확히 평가하기 위해서는 동해 해수순환에 대한 이해가 선행되어야한다. 따라서 본 연구에서는 일본 큐슈대학교 응용역학연구소에서 개발한 RIAMOM 모델을 근간으로 동해 해수순환 모델링을 수행하였다. 모델 영역은 $126.5^{\circ}E{\~}142.5^{\circ}E$ $33^{\circ}N{\~}52^{\circ}N$, 수직층은 20개로 나누었다. 이 모델은 JODC, KNFRDI, 그리고 ECMWF로 부터 구하였다. 모델링 결과, 동해 해수순환을 비교적 잘 모의하고 있는 것으로 나타났다. 향후 모델링 결과를 정량적으로 평가하기 위해 인공위성 추적 부이를 이용하여 확산 검증 실험을 실시할 예정이다.

• 한국대기환경학회지
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• 제15권3호
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• pp.223-233
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• 1999

The wind-flow characteristics over a two-dimensional triangular prism with a porous windbreak are numerically investigated. The geometry is a simplified model of large outdoor stack with a frontal wall-type windbreak which is used to prevent particle dispersion by reducing wind speed over stak surface. In the present numerical model, the RNG k-$\varepsilon$ model, the orthogonal grid system and the QUICK scheme are employed for the successful simulation of separated flow. The predicted results are compared and validated with the associated wind-tunnel experiments. In addition, the trajectories of dispersed particles and their sedimentation characteristics are quantitatively investingated using a Lagrangian turbulent-dispersion model.

• 대기
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• 제25권4호
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• pp.659-667
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• 2015

In this study, sensitivity of inflow wind speed and turbulent Schmidt number to pollutant dispersion in an urban street canyon is investigated, by comparing CFD-simulated results to wind-tunnel results. For this, we changed systematically inflow wind speed at the street-canyon height ($1.5{\sim}10.0m\;s^{-1}$ with the increment of $0.5m\;s^{-1}$) and turbulent Schmidt number (0.2~1.3 with interval of 0.1). Also, we performed numerical experiments under the conditions that turbulent Schmidt numbers selected with the magnitude of mean kinetic energy at each grid point were assigned in the street canyon. With the increase of the inflow wind speed, the model underestimated (overestimated) pollutant concentration in the upwind (downwind) side of the street canyon because of the increase of pollutant advection. This implies that, for more realistic reproduction of pollutant dispersion in urban street canyons, large (small) turbulent Schmidt number should be assigned for week (strong) inflow condition. In the cases of selectively assigned turbulent Schmidt number, mean bias remarkably decreased (maximum 60%) compared to the cases of constant turbulent Schmidt number assigned. At week (strong) inflow wind speed, root mean square error decreases as the area where turbulent Schmidt number is selectively assigned becomes large (small).

• 한국항해항만학회지
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• 제26권5호
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• pp.563-569
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• 2002

오염물질 확산모델링시 기존의 유한차분모델의 단점을 보완하기 위해 입자추적법이 사용되고 있다. 본 연구에서는 Princeton Ocean Model에 결합하여 사용할 수 있는 3차원 입자추적모델을 개발하였으며 이를 다양한 수치실험을 통해 검증하였다. 또한 미국 플로리다 주 템파만의 해양방류구 모델링에 적용하므로써 모델의 유용성을 확인하였다. 예상대로 입자추적모델은 기존의 유한차분모델에 비해 적은 확산범위를 나타내었으며, 이는 기존의 유한차분모델이 안고 있는 수치확산에 따른 오차로 추정된다. 새로이 개발된 모델은 다양한 해양확산모델링에 유용하게 응용될 것으로 기대된다.

• 한국대기환경학회지
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• 제16권3호
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• pp.211-223
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• 2000

The atmospheric dispersion of a pollutant emitted from a hypothetical source located in the middle of the Yochon Industrial Estate was simulated by using the Regional Atmospheric Modeling System (RAMS). Four horizontally nested grids were employed: the coarsest one covered the southern part of the Korean Peninsula including Mt. Chiri and the finest one covered the Yochon Industrial Estate and the surrounding area. Wind fields were initially assumed horizontally homogeneous with a wind speed of 4m/s, the average for the Yosu area, and were developed without both external forces and diurnal changes in order to investigate the terrain-induced phenomena. Wind directions that could emphasize the terrain effects on the pollutant transport and that could carry pollutants to a highly-popluated area were selected for the dispersion study. A pollutant was released for 24hours from a grid-base volume source after a 24-h blank run for developing the wind field. The dispersion study showed that the pollutant from the present source location did not directly affect the Yosu City, but showed high concentrations at locations behind the hills 5 to 6 km away from the source according to wind directions. When the wind speed was low, close to calm condition, the pollutant was detected at upstream locations 6 to 7 km from the source. In comparison with the results from the RAMS simulation, the Industrial Source Complex Short-Term Model(ISCST3) predicted a narrow dispersion that was sensitive to the wind direction. When the wind velocity was affected by the local environment, the ISCST3 calculation using that data also gave a lop-sided result, which was different from the distribution of the pollutant reproduced by RAMS.

• 대한공간정보학회지
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• 제19권3호
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• pp.107-114
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• 2011

본 연구에서는 격자 형태의 지형학적 분산 개념을 이용한 유출해석 시 적절한 격자 해상도 선정을 위해 배수경로 길이의 통계학적 특성과 유역의 동수역학적 매개변수의 변화 양상을 살펴보았다. 배수경로 길이는 지리정보체계의 8방향 흐름방향 알고리즘을 이용하여 산정하였으며, 이로부터 유역의 동수역학적 매개변수를 산정하였다. 분석을 위해 사용된 지형도는 보편적으로 널리 사용되고 있는 1:5,000과 1:25,000 축적을 이용하였으며 각각 5, 10, 15, 20 m와 20, 30, 50, 100, 150, 200 m의 격자 크기를 적용하였다. 분석결과 하천망의 규모에 따라 격자 해상도별 배수 경로 길이의 통계적 특성이 변화함을 볼 수 있었으며, 이로 인해 유역의 동수역학적 매개변수 역시 변화함을 볼 수 있었다. 이러한 변화양상들을 종합적으로 판단하여 볼 때 격자 형태의 지형학적 분산 개념을 이용하여 유출해석을 수행할 경우 1:5,000 지형도의 경우 하천망이 발달된 유역은 격자 해상도 5m, 하천망의 발달이 적은 지역의 경우에는 5~20m의 격자 해상도에서 유역의 지형학적 특성과 동수역학적 특성을 적절히 표현하는 것으로 나타났으며, 1:25,000 지형도는 두 경우 모두 50 m 이하에서 이상의 특성들을 비교적 적절히 표현하는 것으로 나타났다.