• 제목/요약/키워드: local topography

검색결과 216건 처리시간 0.024초

전지구 수문해석 모형의 국내 적용성 평가 (The Application Assessment of Global Hydrologic Analysis Models on South Korea)

  • 손경환;이종대;배덕효
    • 한국수자원학회논문집
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    • 제43권12호
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    • pp.1063-1074
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    • 2010
  • 본 연구의 목적은 전지구 수문해석도구인 지표수문해석모형과 전지구 자료의 적용성을 평가하는데 있다. 이에 적정 지표수문해석모형을 선정하고 관측 댐 상류 유역을 대상으로 모형의 모의 능력을 평가하였다. 전지구 자료는 전 세계를 대상으로 제공되는 기상 및 지형 자료를 이용하였으며, 전지구 자료의 불확실성을 평가하기 위해 자료별 생성되는 유출 결과의 정확도를 분석하였다. 또한 기간별 유출분석을 수행하여 전지구 자료의 활용방안을 마련하였다. 국내 자료를 기반으로 모형의 모의 능력을 분석한 결과 국내의 복잡한 기상 및 지형학적 특성에 대해서 신뢰성 높은 유출모의가 가능한 것으로 확인되었다. 전지구 자료에 대한 모의 결과는 기상정보의 불확실성으로 인해 일단위 유출해석은 다소 부정확한 것으로 나타났으나, 기간별 분석에서는 단위 기간이 증가함에 따라 유출 결과의 정확도가 향상되었으며, 10일 단위 이상의 유출분석이 적절한 것으로 나타났다.

동해안의 복잡지형에서 기상장 개선에 따른 CALPUFF 모델의 평가 (Evaluation of the CALPUFF Model Using Improved Meteorological Fields in Complex Terrain of East Sea Coast)

  • 이종범;김재철
    • 한국대기환경학회지
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    • 제25권1호
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    • pp.15-25
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    • 2009
  • Donghae city is one of the most representative cement industrial city in Korea. The area is faced with the East Sea to the East and with high montane region of Tae-Back mountain range to the West. Many pollutant sources of air pollution are located near the coast, but the largest point sources of the region are located at the bottom of the mountain area in Donghae city. The local wind is highly affected by local topography and plays an important role in transport and dispersion of contaminants from the pollution sources. This study was designed to evaluate enhancement of MM5 predictions by using Four Dimensional Data Assimilation (FDDA), the SONDE data and the national meteorological station, data only. The alternative meteorological fields predicted with and without FDDA were used to simulate spatial and temporal variations of NOx in combined with Atmospheric Dispersion Models (CALPUFF). For the modeling domain, the alternative meteorological fields with 1.1 km spatial resolution were interpolated to the CALMET with 0.5 km resolution. The vertical layers set to have 35 and 12 layers for MM5 and CALPUFF, respectively. MM5 with the FDDA did not resulted in significant improvement of meteorological field prediction in Donghae region, which is primarily because of complex geography and wind scheme. The result of CALPUFF, however, showed reduction of uncertainty errors by using the interpolation scheme of the actual measurement data.

Long-Term Investigation of Regional Topographic Effects on Soil Chemical Properties and Heavy Metal Concentrations in Paddy Fields

  • Ahn, Byung-Koo;Kang, Seong-Soo;Shin, Jae-Yeon;Lee, Jin-Ho
    • 한국토양비료학회지
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    • 제45권5호
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    • pp.738-743
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    • 2012
  • Topographic conditions of agricultural fields work as a important factor to identify different soil properties. This study was conducted to investigate the selected soil chemical properties and the concentrations of heavy metals, Cd, Cr, Pb, Cu, Ni, and Zn, in the paddy fields of different topographic areas at four year intervals from 1999 to 2011. Three-hundred soil sampling sites in the paddy fields were selected from the different topographic areas that were local valley and fans, fluvio-marine deposits, alluvial plains, and diluvial terraces. The mean values of soil pH ranged 5.7~5.8 that were within optimal range for rice cultivation. The mean values of other properties such as soil organic matter (SOM) content, the concentrations of exchangeable cations, $K^+$, $Ca^{2+}$, and $Mg^{2+}$, and available silicate concentration were lower or close to the optimal values, but the mean concentrations of available phosphorus were exceeded the range of optimal value, $80{\sim}120mg\;kg^{-1}$, in many paddy fields. In particular, The concentrations of available phosphorus in the paddy fields of local valley and fans, alluvial plains, and fluvio-marine plains were mostly declined. However, in diluvial terrace areas, the phosphorus concentrations unexpectedly increased; furthermore, they were significantly higher than those in other topographic areas. The mean concentrations of 0.1 M HCl-extractable heavy metals, Cd, Cr, Pb, Cu, Ni, and Zn, in the paddy fields were slightly and gradually declined during the study years, but the Pb concentrations were not statistically changed. In addition, the concentrations of heavy metals were widely ranged depending on the different sampling sites. Nevertheless, the concentrations of heavy metals were significantly lower than the levels of Soil Contamination Warning Standard (SCWS) for agricultural lands (1-region) presented in Soil Environment Conservation Law (SECL).

배수(排水) Catena에 있어서 세입질(細粒質) 화강암(花崗岩) 토양(土壤)의 특성(特性) (평택군(平澤郡) 현덕면(玄德面), 화양리(華陽里)) (The Characteristics of Fine Granitic Soils on a Drainage Catena in Hwayang Ri, Pyeongtaeg Area)

  • 임상규;정석재;문준;엄기태
    • 한국토양비료학회지
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    • 제18권3호
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    • pp.276-281
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    • 1985
  • 배수연쇄(排水連鎖)에 따른 세립질(細粒質) 화강암(花崗岩)의 풍화(風化) 모재물(母材物)에 기인(基因)된 식양질(植壤質)인 송정통(松汀統)(잔적토(殘積土)), 대곡통(大谷統)(곡간충적붕적토(谷間沖積崩積土)), 지산(芝山) 및 옥천통(玉泉統)(곡간충적토(谷間沖積土))의 형태적(形態的) 이화학적(理化學的) 특성(特性)을 조사연구(調査硏究)한 결과(結果)는 1. 이들 토양(土壤)은 연쇄성(連鎖性)(Catena)이 인정(認定)되며 또한 지형(地形) 지하수위(地下水位) 및 활성철함량(活性鐵含量) 때문에 토색연쇄(土色連鎖)(Soil color sequence)를 가진다. 2. 배수(排水)가 불량(不良)할 수록 미사(微砂)/점토율(粘土率), 토양산도(土壤酸度), 유기물(有機物) 및 유효인산함량(有效燐酸含量)은 증가(增加)하였으나 활성철함량(活性鐵含量)은 그 반대(反對)인 경향(傾向)이었다.

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CFD_NIMR_SNU 모형을 활용한 은평구 건설 전후의 바람환경 변화 모사 연구 (Wind Field Change Simulation before and after the Regional Development of the Eunpyeong Area at Seoul Using a CFD_NIMR_SNU Model)

  • 조경미;구해정;김규랑;최영진
    • 환경영향평가
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    • 제20권4호
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    • pp.539-555
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    • 2011
  • Newly constructed, high-rise dense building areas by urban development can cause changes in local wind fields. Wind fields were analyzed to assess the impact on the local meteorology due to the land use changes during the urban redevelopment called "Eunpyeong new town" in north-western Seoul using CFD_NIMR_SNU (Computational Fluid Dynamics, National Institute of Meteorological Research, Seoul National University) model. Initial value of wind speed and direction use analysis value of AWS (Automatic Weather Station) data during 5 years. In the case of the pre-construction with low rise built-up area, it was simulated that the spatial distribution of horizontal wind fields depends on the topography and wind direction of initial inflow. But, in the case of the post-construction with high rise built-up area, it was analyzed that the wind field was affected by high rise buildings as well as terrain. High-rise buildings can generate new circulations among buildings. In addition, small size vortexes were newly generated by terrain and high rise buildings after the construction. As high-rise buildings act as a barrier, we found that the horizontal wind flow was separated and wind speed was reduced behind the buildings. CFD_NIMR_SNU was able to analyze the impact of high-rise buildings during the urban development. With the support of high power computing, it will be more common to utilize sophisticated numerical analysis models such as CFD_NIMR_SNU in evaluating the impact of urban development on wind flow or channel.

황해동측 연안성의 조류 및 풍성류 모형 (Modeling of Tidal and Wind-Driven Currents in Eastern Coastal Waters of the Yellow Sea)

  • Ro, Young-Jae;You, Ik-Hwan
    • 한국해안해양공학회지
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    • 제4권4호
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    • pp.231-242
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    • 1992
  • 분 연구에서는 수치모형을 이용하여 조류 및 취송류의 순환형태를 고찰하였다. 사용된 모형은 유체의 운동 및 연속방정식에 기초한 연직평균 2차편 모형으로서 양해법을 사용하며, 개방경계에서의 해수면 변화와 바람의 전단력에 의한 forcing을 포함한다. 모형의 영역은 북위 35$^{\circ}$~36$^{\circ}$40', 동경 125$^{\circ}$~126$^{\circ}$40'이며 경사간격은 x, y 방향 공히 5km이다. 피해측에서 22일간 관측된 조석(2개 지점) 및 조류(1개 지점) 자료와 비교한 결과 본 모형은 4개 주요 분조에 의한 조석 및 조류를 정확도 90% 이내로 재현하였다. 여섯 가지 경우의 가상적인 바람에 대한 해석을 통하여 흐름의 분포양상과 지역적인 특성을 고찰하였다. 그 결과, 풍향에 관계 없이 강한 연안류가 발생하며, 또한 해저지형의 영향으로 부안 외해측에 주반경 40km의 지역적인 과류가 발생함을 확인하였다.

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자연하천 형상을 이용한 최적 흐름분배 알고리즘의 개발 (Development of Optimized Flow Apportioning Algorithm Using Natural Stream Morphology)

  • 김상현;이학수;강창용;김남원
    • 한국수자원학회논문집
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    • 제35권4호
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    • pp.345-358
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    • 2002
  • 수치고도모형을 이용한 흐름분배 알고리즘들은 지형을 따른 흐름의 분산특성을 잘 기술해 주는 방향으로 발달되어 왔지만, 수로격자의 연결성, 지형기복을 따른 다양한 분산특성, 수로격자크기 등과 관련한 한계성을 가지고 있다. 기존 흐름 알고리즘들이 흐름분배 결정에 사용한 지형 데이터들은 수치고도모형에서 산출가능한 흐름누적면적과 경사도로서 유역내 지배적인 흐름경로인 수로격자의 위치와 크기에 대한 고려를 하지 않는다. 따라서 본 연구에서는 기존 알고리즘들의 단점인 수로의 연결성과 복잡한 지형을 따른 다양한 흐름분산 특성을 기술할 수 있는 흐름 분배 알고리즘을 제안하고, 유전자 알고리즘을 이용하여 수로격자의 위치와 크기를 가장 잘 표현할 수 있도록 최적화하였으며, 기존의 방법에 비해 개선된 결과를 얻을 수 있었다.

강우-유출 모델링의 불확실성 고려한 다중 평가지수에 의한 확장형 모형평가 방법 (An Extended Model Evaluation Method using Multiple Assessment Indices (MAIs) under Uncertainty in Rainfall-Runoff Modeling)

  • 이기하;정관수;타치카와 야수토
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2010년도 학술발표회
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    • pp.591-595
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    • 2010
  • Conventional methods of model evaluation usually rely only on model performance based on a comparison of simulated variables to corresponding observations. However, this type of model evaluation has been criticized because of its insufficient consideration of the various uncertainty sources involved in modeling processes. This study aims to propose an extended model evaluation method using multiple assesment indices (MAIs) that consider not only the model performance but also the model structure and parameter uncertainties in rainfall-runoff modeling. A simple reservoir model (SFM) and distributed kinematic wave models (KWMSS1 and KWMSS2 using topography from 250m, 500m, and 1km digital elevation models) were developed and assessed by three MAIs for model performance, model structural stability, and parameter identifiability. All the models provided acceptable performance in terms of a global response, but the simpler SFM and KWMSS1 could not accurately represent the local behaviors of hydrographs. In addition, SFM and KWMSS1 were structurally unstable; their performance was sensitive to the applied objective functions. On the other hand, the most sophisticated model, KWMSS2, performed well, satisfying both global and local behaviors. KMSS2 also showed good structural stability, reproducing hydrographs regardless of the applied objective functions; however, superior parameter identifiability was not guaranteed. Numerous parameter sets could lead to indistinguishable hydrographs. This result supports that while making a model complex increases its performance accuracy and reduces its structural uncertainty, the model is likely to suffer from parameter uncertainty. The proposed model evaluation process can provide an effective guideline for identifying a reliable hydrologic model.

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Electrical Characterization of Nanoscale $Au/TiO_2$ Schottky Diodes Probed with Conductive Atomic Force Microscopy

  • Lee, Hyunsoo;Van, Trong Nghia;Park, Jeong Young
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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    • pp.290.1-290.1
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    • 2013
  • The electrical characterization of Au islands on TiO2 at nanometer scale (as a Schottky nanodiode) has been studied with conductive atomic force microscopy in ultra-high vacuum. The diverse sizes of the Au islands were formed by using self-assembled patterns on n-type TiO2 semiconductor film using the Langmuir-Blodgett process. Local conductance images showing the current flowing through the TiN coated AFM probe to the surface of the Au islands on TiO2 was simultaneously obtained with topography, while a positive sample bias is applied. The boundary of the Au islands revealed a higher current flow than that of the inner Au islands in current AFM images, with the forward bias presumably due to the surface plasmon resonance. The nanoscale Schottky barrier height of the Au/TiO2 Schottky nanodiode was obtained by fitting the I-V curve to the thermionic emission equation. The local resistance of the Au/TiO2 nanodiode appeared to be higher at the larger Au islands than at the smaller islands. The results suggest that conductive atomic force microscopy can be used to reveal the I-V characterization of metal size dependence and the electrical effects of surface plasmon on a metal-semiconductor Schottky diode at nanometer scale.

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관측망 밀도가 기상 자료의 격자형 수평 분포에 미치는 영향 (Effects of Network Density on Gridded Horizontal Distribution of Meteorological Variables in the Seoul Metropolitan Area)

  • 강민수;박문수;채정훈;민재식;정보연;한성의
    • 대기
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    • 제29권2호
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    • pp.183-196
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    • 2019
  • High-quality and high-resolution meteorological information is essential to reduce damages due to disastrous weather phenomena such as flash flood, strong wind, and heat/cold waves. There are many meteorological observation stations operated by Korea Meteorological Administration (KMA) in Seoul Metropolitan Area (SMA). Nonetheless, they are still not enough to represent small-scale weather phenomena like convective storm cells due to its poor resolution, especially over urban areas with high-rise buildings and complex land use. In this study, feasibilities to use additional pre-existing networks (e.g., operated by local government and private company) are tested by investigating the effects of network density on the gridded horizontal distribution of two meteorological variables (temperature and precipitation). Two heat wave event days and two precipitation events are chosen, respectively. And the automatic weather station (AWS) networks operated by KMA, local-government, and SKTechX in Incheon area are used. It is found that as network density increases, correlation coefficients between the interpolated values with a horizontal resolution of 350 m and observed data also become large. The range of correlation coefficients with respect to the network density shows large in nighttime rather than in daytime for temperature. While, the range does not depend on the time of day, but on the precipitation type and horizontal distribution of convection cells. This study suggests that temperature and precipitation sensors should be added at points with large horizontal inhomogeneity of land use or topography to represent the horizontal features with a resolution higher than 350 m.