• Journal of Korea Water Resources Association
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• v.44 no.3
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• pp.209-220
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• 2011

Input uncertainty is one of the major sources of uncertainty in hydrologic modeling. In this paper, first, three alternate rainfall inputs generated by different interpolation schemes were used to see the impact on a distributed watershed model. Later, the residuals of precipitation interpolations were tested as a source of ensemble streamflow generation in two river basins in the U.S. Using the Monte Carlo parameter search, the relationship between input and parameter uncertainty was also categorized to see sensitivity of the parameters to input differences. This analysis is useful not only to find the parameters that need more attention but also to transfer parameters calibrated for station measurement to the simulation using different inputs such as downscaled data from weather generator outputs. Input ensembles that preserves local statistical characteristics are used to generate streamflow ensembles hindcast, and showed that the ensemble sets are capturing the observed steamflow properly. This procedure is especially important to consider input uncertainties in the simulation of streamflow forecast.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.144-144
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• 2012

하천 제방의 안정성을 평가하기 위해서는 홍수시 제방 주변의 흐름특성을 분석하는 것이 필요하다. 일반적으로 홍수시 유속은 측정된 홍수량을 이용한 단면평균유속을 이용하여 평가를 하고 있기 때문에 제방 주변의 흐름특성을 정확하게 분석하는데 한계가 있다. 이를 개선하기 위해서는 홍수시 제방 주변의 유속을 측정하여야 하는데 접근이 어렵고 위험하기 때문에 봉부자 또는 유속계를 이용한 유속측정이 어려운 실정이다. 이와 같은 경우 제방 주변의 영상 분석을 이용한 표면영상유속계의 활용이 좋은 대안이 될 수 있다. 표면영상유속계의 경우 원거리에서도 줌을 이용하여 영상을 획득할 수 있고, 측정 시간이 짧기 때문에 제방 주변의 유속을 간편하게 측정 가능하다. 하지만 표면영상유속계(SIV)는 영상좌표와 물리좌표 사이의 좌표 변환을 필요로 한다. 종전까지는 일반적으로 8-변수 좌표 변환법이 널리 이용되었으나, 이 방법은 최소한 4점 이상의 참조점이 필요하기 때문에 수면위에 참조점을 설치해야 하는 어려움이 있다. 또한, 내삽을 하는 방법이기 때문에 참조점 내부의 점에 대해서는 비교적 정확한 변환이 가능하지만, 참조점 외부의 좌표들에 대해서는 부정확한 변환이 되는 단점이 있었다. 따라서 본 연구에서는 카메라 모형을 이용하여, 새로운 좌표 변환식을 유도하였다. 이 영상좌표 변환식은 참조점을 이용하지 않으며, 수면과 카메라간의 연직 거리와 카메라의 기울어진 각도만을 이용하여 좌표 변환이 가능한 방법이다. 참조점을 필요로 하지 않기 때문에 측량의 번거로움이 없으며, 변환식내에서 내삽을 하지 않기 때문에 영상 전체에 대해 고른 좌표 변환이 가능한 장점을 지니고 있다.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.360-366
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• 2009

AQUA/AMSR-E 인공위성 자료를 활용하여 3차원 최적내삽 해수면온도 합성장을 생산하였고 시간평균장과 비교하여 문제점과 한계점을 기술하였다. 3-D SST 합성장은 북태평양 중앙부에서 전체적으로 $0.05^{\circ}C$ 이하의 작은 오차를 보였으나, 위성 결측이 있는 연안에서는 $0.4^{\circ}C$ 이상의 비교적 큰 오차를 유발하였다. 강한 강수나 구름으로 인한 결측이 있는 부분에서는 $0.1\sim0.15^{\circ}C$에 달하는 오차를 보였다. 시간평균장과 비교한 결과, 구름 부근의 화소에서는 해수면온도를 낮게 계산하는 경향이 있었으며, 해수면온도의 공간적 구배를 감소시키는 평활화가 전체적으로 나타났다. 저위도에서 OI SST는 실제 해수면온도에는 없는 불연속성을 만드는 경향이 있었고, 이는 OI 과정에서 사용한 윈도우의 크기와 해양 현상의 수평 규모가 위도에 따라 변화하는데서 기인하였다. 현상의 공간 규모의 척도인 로스비 내부 변형 반경은 북태평양에서 O(1) 정도로 위도에 따른 공간적 변화가 큰 것으로 나타났다. 본 연구는 SST 합성장 생산 과정에 위도와 해수의 수직적 밀도 구조와 밀접한 관련이 있는 해양 현상의 수평적 규모의 시공간적 변동 특성을 고려해야 함을 제시한다.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.63-73
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• 2010

Rainfall is one of the most important input data of hydrologic models. Rain gage is used to estimate areal rainfall for hydrologic models using several interpolation method such as Thiessen polygon, Inverse Distance Squared(IDS) and Kriging. However, it is still difficult to derive actual spatial distribution of the rainfall using the aforementioned approaches. On the other hand, radar can offer a significant analytic improvement for rainfall analysis by providing directly more representative of the true spatial distribution of rainfall. In this study, In this study, spatial distributions of rainfall derived form rain gages using IDS and Kriging and rainfall from radar are compared. As results, it is found that using radar can provide actual spatial distribution than rain gages.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.2
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• pp.95-102
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• 2002

Spatial interpolation has become a common procedure in converting temperature forecasts and observations at irregular points for use in regional scale ecosystem modeling and the model based decision support systems for resource management. Neglection of terrain effects in most spatial interpolations for short term temperatures may cause erroneous results in mountainous regions, where the observation network hardly covers full features of the complicated terrain. A spatial interpolation model for daytime hourly temperature was formulated based on error analysis of unsampled site with respect to the site topography. The model has a solar irradiance correction scheme in addition to the common backbone of the lapse rate - corrected inverse distance weighting. The solar irradiance scheme calculates the direct, diffuse and reflected components of shortwave radiation over any surfaces based on the sun-slope geometry and compares the sum with that over a reference surface. The deviation from the reference radiation is used to calculate the temperature correction term by an empirical conversion formula between the solar energy and the air temperature on any sloped surfaces at an hourly time scale, which can be prepared seasonally for each land cover type. When this model was applied to a 14 km by 22 km mountainous region at a 10 m horizontal resolution, the estimated hourly temperature surfaces showed a better agreement with the observed distribution than those by a conventional method.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.389-406
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• 2004

with the increasing popularity of regional studies, the importance of regional data has been recognized dramatically in recent years. However, due to potential problems from the intrinsic characteristics of aggregate regional data for the research, and incompatible regional units between source and target regional data units, the method for reorganizing the regional data units for a given research analysis should be required. In this regard, the purpose of this research is to review the significant interpolation methods for reorganizing the data units and, based on it, to propose the population weighted interpolation method. For the first purpose, areal weighted interpolation method, pycnophylactic method, dasymetric method, area-to-point method were reviewed. The proposed population-weighted interpolation method was applied to the case study of population census regional data in Erie County, NY, compared with areal weighted interpolation method, pycnophylactic method in terms of several statistical characteristics.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.96-104
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• 2001

Usage of ecosystem models has been extended to landscape scales for understanding the effects of environmental factors on natural and agro-ecosystems and for serving as their management decision tools. Accurate prediction of spatial variation in daily temperature is required for most ecosystem models to be applied to landscape scales. There are relatively few empirical evaluations of landscape-scale temperature prediction techniques in mountainous terrain such as Korean Peninsula. We derived a periodic function of seasonal lapse rate fluctuation from analysis of elevation effects on daily temperatures. Observed daily maximum and minimum temperature data at 63 standard stations in 1999 were regressed to the latitude, longitude, distance from the nearest coastline and altitude of the stations, and the optimum models with $r^2$ of 0.65 and above were selected. Partial regression coefficients for the altitude variable were plotted against day of year, and a numerical formula was determined for simulating the seasonal trend of daily lapse rate, i.e., partial regression coefficients. The formula in conjunction with an inverse distance weighted interpolation scheme was applied to predict daily temperatures at 267 sites, where observation data are available, on randomly selected dates for winter, spring and summer in 2000. The estimation errors were smaller and more consistent than the inverse distance weighting plus mean annual lapse rate scheme. We conclude that this method is simple and accurate enough to be used as an operational temperature interpolation scheme at landscape scale in Korea and should be applicable to elsewhere.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1053-1064
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• 2022

The Thiessen method, which is the current area average precipitation method, has serious structural limitations in accurately calculating the average precipitation in the watershed. In addition to the observation accuracy of the precipitation meter, errors may occur in the area average precipitation calculation depending on the arrangement of the precipitation meter and the direction of the heavy rain. When the watershed is small and the station density is sparse, in both simulation and observation history, the Thiessen method showed a peculiar tendency that the average precipitation in the watershed continues to increase and decrease rapidly for 10 minutes before and after the peak. And the average precipitation in the Thiessen basin was different from the rainfall radar at the peak time. In the case where the watershed is small but the station density is relatively high, overall, the Thiessen method did not show a trend of sawtooth-shaped over-peak, and the time-dependent fluctuations were similar. However, there was a continuous time lag of about 10 minutes between the rainfall radar observations and the ground precipitation meter observations and the average precipitation in the basin. As a result of examining the ground correction effect of the rainfall radar watershed average precipitation, the correlation between the area average precipitation after correction is rather low compared to the area average precipitation before correction, indicating that the correction effect of the current rainfall radar ground correction algorithm is not high.

• Journal of the Korean Geographical Society
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• v.44 no.2
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• pp.105-121
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• 2009

The accurate official map of air temperature does not exist for the Hawaiian Islands due to the limited number of weather stations on the rugged volcanic landscape. To alleviate the major problem of temperature mapping, satellite-measured land surface temperature (LST) data were used as an additional source of sample points. The Moderate Resolution Imaging Spectroradiometer (MODIS) system provides hypertemperal LST data, and LST pixel values that were frequently observed (${\ge}$14 days during a 32-day composite period) had a strong, consistent correlation with air temperature. Systematic grid points with a spacing of 5km, 10km, and 20km were generated, and LST-derived air temperature estimates were extracted for each of the grid points and used as input to inverse distance weighted (IDW) and cokriging methods. Combining temperature data and digital elevation model (DEM), cokriging significantly improved interpolation accuracy compared to IDW. Although a cokriging method is useful when a primary variable is cross-correlated with elevation, interpolation accuracy was sensitively influenced by the seasonal variations of weather conditions. Since the spatial variations of local air temperature are more variable in the wet season than in the dry season, prediction errors were larger during the wet season than the dry season.

• Journal of the Korean association of regional geographers
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• v.16 no.1
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• pp.48-58
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• 2010

Currently, understanding the characters of Rural Industrial Parks' regional distribution is insufficient. Therefore, regional characters of the Rural Industrial Parks all over the country were studied through indications such as sales, worker-sales increase rate, worker increase rates. Portfolio analysis and IDW by using ArcView 3.2 were used as a method of analysis. As a result, most of the Rural Industrial Parks' size and size increase rate showed low figures. Respective regional analysis shows that there is an increase in the scale of the Kyungnam area using portfolio analysis, whereas the scale of Chonbuk is high using IDW. As a result, it shows that there is difference on the scale between Rural Industrial Parks when individual or Associated with peripheral. Therefore, not only do the Rural Industrial Parks need stimulation individually, but adjacent parks need to be supported and managed.