• Journal of Korea Water Resources Association
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• v.42 no.5
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• pp.385-396
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• 2009

The spatial distribution of precipitation trends according to urbanization, geographical and topographical conditions have been studied. In this study, precipitation data from 1973 to 2006 were analyzed for 56 climatological stations including the Seoul metropolis in South Korea. In addition to annual average daily precipitation, monthly average daily precipitation in April, July, October and January were analyzed, considering seasonal effect. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicate that annual average precipitation increased, and monthly average precipitation in April and October decreased, while those in January and July increased. Considering urbanization effect, annual average precipitation and monthly average precipitation in July increased; however, monthly average precipitation in January, April and October decreased. Furthermore, compared with urbanization rate and proximity to coast, average elevation of study area appeared to be the most close correlation with annual and monthly averages of precipitation trends.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.379-379
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• 2011

본 연구는 우리나라 전국 기상관측소 중 1973년부터 2009년까지의 시 강수자료가 구축되어 있는 기상관측소 55개 지점에 대하여 비정상성 빈도해석을 수행하였다. 각 지점에 대하여 지속시간 1시간, 24시간에 대한 연 최대 강수량 자료를 구축하여 초기 20년을 기준으로 1년씩 추가한 연 최대 강수량 누적 자료를 생성하고, 생성된 기간별 자료의 평균, 위치매개변수, 축척매개변수를 산정하였으며, 위치매개변수와 축척매개변수는 확률가중모멘트법을 사용하여 산정하였다. 산정된 연 최대 평균 누적 강수량과 연도와의 선형 회귀식을 산정하여 목표연도별(2040, 2070, 2100년) 평균 강수량을 산정하였고, 위치매개변수와 축척매개변수도 평균 누적 강수량과의 선형 회귀식을 산정함으로써, 목표연도에 해당하는 각 매개변수를 산정하였다. 또한 산정된 목표연도별 평균 강수량, 위치매개변수와 축척매개변수를 이용해 확률강수량을 산정하였다. 비정상성 빈도해석을 수행하여 산정된 55개 지점에 대한 목표연도별 확률강수량을 Inverse Distance Weighted(IDW) 보간법을 사용하여 전국의 확률강수량을 공간적으로 표현하였다. 전국단위의 비정상성 빈도해석을 실시한 결과, 전체적으로 각 목표연도별 확률강수량이 증가하는 것으로 나타났으나, 일부 감소하는 지역도 나타났다. 경기도와 강원도 등 중부지역에서 확률강수량의 증가가 큰 것으로 나타났으며, 특히 강원도(강릉, 인재 등) 지역에서 확률강수량의 증가폭이 가장 크게 나타났다. 또한 남해지역에서는 대부분 확률강수량이 감소하는 것으로 나타났고, 그중에서 전라남도 남해안 부근(장흥 등)에 확률강수량의 감소가 가장 크게 나타났으며, 경북지역과 전북지역 부근에서는 증가 또는 감소의 차이가 미비하게 나타났다. 하지만 목표연도 2070년과 2100년에 대하여 산정된 확률강수량으로부터 선형 회귀식을 통해 목표연도별 평균 강수량, 위치매개변수, 축척매개변수를 추정하여 확률강수량을 산정하는 것에 한계가 있음을 보여주었다.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.2
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• pp.260-267
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• 2011

This paper proposes a method for segmenting objects from the background in IR(Infrared) images based on GrabCut algorithm. The GrabCut algorithm needs the window encompassing the interesting known object. This procedure is processed by user. However, to apply it for object recognition problems in image sequences. the location of window should be determined automatically. For this, we adopted the Otsu' algorithm for segmenting the interesting but unknown objects in an image coarsely. After applying the Otsu' algorithm, the window is located automatically by blob analysis. The GrabCut algorithm needs the probability distributions of both the candidate object region and the background region surrounding closely the object for estimating the Gaussian mixture models(GMMs) of the object and the background. The probability distribution of the background is computed from the background window, which has the same number of pixels within the candidate object region. Experiments for various IR images show that the proposed method is proper to segment out the interesting object in IR image sequences. To evaluate performance of proposed segmentation method, we compare other segmentation methods.

• 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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.3
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• pp.143-149
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• 2001

This study was conducted to analyze the propertis, acidity and chemical compositions of the snowfall in the bare land and Idlest stand. The research sites of this study are the Daegwalyung (a high hill) and Woongyori in Pyungchang-gun, Kangwon province. The results of this study are as follows: The snowfall pH showed large changes when the snowfall was small. The more snow falls, the smaller changes of the pH are narrow. According to the local conditions, it means that the acid deposition changed over adsorption ratio in suspended matters of the atmosphere. Changes of the ion concentrations for the snowfall in the forest stand showed a thendency to increase. Chemical composition of the snowfall for each sampling site showed that the ion concentrations of $Ca^{2+}$and anions had higher value than other ions.s.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.255-266
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• 2010

In high-rise buildings, an outrigger system is frequently used as a resisting system for lateral loads. Since the outriggers tie exterior columns and an interior core, exterior columns can participate in the lateral load resisting system and the structural resistance capacity can be increased. However, the outriggers contribute for controlling gravity loads as well as lateral loads. The flows of gravity loads can be changed by the members of outriggers, for the purposes of transferring loads to mega-columns, distributing gravity loads equally among vertical members of columns, walls, or piles, minimizing differential settlements in a foundation system, and so on. In this study, by computational structural analyses of high-rise buildings over 100 floors, the effects of outriggers on controlling gravity loads are analyzed. Analyses for 3-dimensional models with or without outrigger members are performed, and then the gravity load distributions in columns and piles and foundation settlements are analyzed. Also, the effects of outriggers on gravity load controls during construction stages as well as after construction are included.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.655-669
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• 2018

In this study, we developed a hybrid forecasting model based on a four-parameter distribution which allows a simultaneous season-ahead forecasting for both seasonal rainfall and sub-daily rainfall in Han-River and Geum-River basins. The proposed model is mainly utilized a set of time-varying predictors and the associated model parameters were estimated within a Bayesian nonstationary rainfall frequency framework. The hybrid forecasting model was validated through an cross-validatory experiment using the recent rainfall events during 2014~2017 in both basins. The seasonal precipitation results showed a good agreement with the observations, which is about 86.3% and 98.9% in Han-River basin and Geum-River basin, respectively. Similarly, for the extreme rainfalls at sub-daily scale, the results showed a good correspondence between the observed and simulated rainfalls with a range of 65.9~99.7%. Therefore, it can be concluded that the proposed model could be used to better consider climate variability at multiple time scales.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.329-332
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• 2008

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete structures, and the concept of the effective moment of inertia has been generally used for the estimation of beam deflections. The KCI design code adopted Branson's equation for the calculation of the effective moment of inertia, which was formulated based on the results of beam tests subjected to uniformly distributed loads. Therefore, it is worthwhile to check the applicability of the code approach on the estimation of the effective moment of inertia for the cases of beams under different loading conditions. In this study, an experimental investigation has been conducted on six beams, where primary variables were concrete compressive strengths and loading distances from supports. The test results were compared with various approaches proposed by Branson and others as well. The test results indicated that the effective moment of inertia was somewhat influenced by the moment distribution shape. Despite the different moment distribution shapes for specimens, however, the effective moment of inertia of all test beams were closely predicted by the existing methods considered in this study.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.192-206
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• 1994

The freshwater fish fauna of the Tokyusan National Park was censused during June 1993 to November 1993 at 9 sampling sites to establish baseline data for natural conservation program on the National Park. Seventeen species included 7 Korean endemic species and/or subspecies(Acheilognaths koreunus, Squazidus gracilis majimae, Microphysogobio yaluensis, Phoxinus kumganensis, Cobitis koreensis koreensis, Silurus microdorsalis and Odontobutis platycephala) belonging to 5 families were collected in this region. Sixteen species were found in Kumkang and 8 species were found in Naktongkang, however, common species were Squalidus gracilis majimae, Microphysogobio yaluensis, Puntungia herzi, Moroco oxycephalus, Zucco temminckii, Misgurnus anguillicaudatus and Odontobutis platycephala. Dominant species of this region were Moroco oxycephalus, Zacco temminckii, Odontobutis platycephala. The final aims of this study were not only accumulate baseline data on the osteology of Korean freshwater fishes which were collected at those streams during June 1993-November 1993 with soft X-ray radiography, but also evaluate the suitability of osteological analyses on the environmental damage to fish.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1784-1788
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• 2010

APEC 기후센터(APEC Climate Center, APCC)에서 제공하는 다중모형앙상블(Multi-model Ensemble, MME) 형태의 계절예측정보를 이용하여 3개월 가뭄전망을 수행하였다. APCC MME는 기후예측모형이 가지는 불확실성을 최소화하기 위한 방법으로, 아시아 태평양 지역 내 9개 회원국 16개 기관 21개 기후모형의 계절예측정보를 활용하여, 개별 모형이 가지는 계통오차(Systematic error)를 앙상블 기법을 통하여 상쇄함으로써 최적의 예측자료를 도출한다. 또한, 기후예측 모형이 예측한 대기순환장은 관측 지점변수와 경험적 통계적 관련성을 가지므로, 이를 바탕으로 상세지역의 이상기후에 대한 정보를 도출할 수 있다. 본 연구에서는 가뭄 관리 및 전망을 위한 입력 자료로서, 기상전문 기관인 APEC 기후센터 (APEC Climate Center, APCC)에서 제공하는 전구 규모의 기온 및 강수 전망자료를 기상청 산하 59개 지점의 전망자료로 통계적 규모 축소화 기법을 통해 3개월 예보를 실시하였다. APCC 계절예측자료를 가뭄모니터링시스템의 자료입력 포맷에 따라 적절히 가공한 뒤, 가뭄 관리 및 전망을 위하여 SPI(Standard Precipitation Index) 및 PDSI(Palmer Drought Severity Index)지수의 입력자료로 사용하여 SPI 및 PDSI 지수를 산정하였다. 또한 분위사상법(Quantile Mapping)을 이용하여 총 59개 지점의 과거 월평균 관측값과 최근 2009년에 대한 모의값의 누적확률분포값을 계산하고 모의값의 확률분포를 관측값의 확률분포에 사상시켜 가뭄 전망을 위한 기상변수의 오차를 보정하고자 하였다. 이러한 계절예측정보를 이용하여 가뭄 전망에 대한 신뢰도가 높아진다면, 사전예방 및 피해완화로 가뭄상황에 대한 신속한 대처 및 피해의 경감이 이루어질 수 있을 것이다.