• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.681-686
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• 2004

수공구조물의 설계를 위해서는 해당 수공구조물의 중요도에 따른 설계빈도 및 설계유량과 설계수위 등의 설정이라는 과정이 필요하다. 설계빈도는 하천설계기준에 제시되어 있는 바와 같이 시설물의 입지조건과 중요도에 따라 기준이 제시되어 있으며 설계홍수량은 확률강우량을 기초로 한 설계강우를 결정하고, 결정된 설계우량에 의한 유출량의 산정작업이 필요하다. 이와 같은 설계수량의 산정에 있어서 설계강우의 지속기간 설정은 매우 중요한 작업이다. 일반적으로 동일한 설계빈도의 홍수량은 지속기간에 따라 많은 차이를 보이고 있다. 따라서 설계강우의 지속시간 설정은 매우 중요한 설계인자가 되므로 본 연구에서는 IHP유역인 위천유역을 대상으로 최근 권장되고 있는 설계강우의 지속시간 선정을 위한 개념인 임계지속기간을 산정하여 임계지속기간에 영향을 미치는 수문인자들에 대해 살펴보고자 한다. 본 연구에서는 IHP 유역인 위천 유역(동곡 외 4개 소유역)을 대상으로 설계홍수량의 첨두유출량이 최대로 발생하는 강우지속기간을 임계지속기간으로 설정하였으며, 설계홍수량의 산정시 설계강우로부터 홍수량을 산정하기 위한 일련의 절차에서 이용되는 각종 수문요소들, 즉 강우시간분포와 유효우량 산정방법, 유출모형 그리고 면적의 변화에 따른 임계지속기간의 변화를 연구하였다. 본 연구에서는 임계지속기간의 개념을 고려할 설계강우의 지속기간을 산정하기 위해 필요한 각 수문요소별 산정방법은 국내 자료로부터 제안된 방법을 우선 사용하였으며, 임계지속기간의 개념에 따른 설계강우의 지속기간 산정을 위해 확률강우량 산정, 강우의 시간분포(Huff 분포, Yen & Chow의 삼각형 분포), 유효우량 산정방법(AMC-II, AMC-III, CN37), 대표단위도와 6가지 합성단위도법을 적용하였다. 산정 된 결과로부터 임계지속기간 산정에 영향을 주는 각 수문인자 중 강우시간분포와 유효우량 산정방법 그리고 유출모형에 대해 자자 검토하였으며, 최종적으로 면적에 따른 임계지속기간과 유출량의 변화를 검토해 보았다.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.561-564
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• 1998

The radial distribution functions of a linear spheroidal type gas molecule $C_2H_4$ were calculated by using the Stockmayer molecular molel, which assumed the $C_2H_4$ molecule as simple quadrupolar molecule. To examine the validity of the calculated radial distribution of $C_2H_4$ gas, the density dependent pressures of $C_2H_4$ gas at several temperatures were calculated and compared with literarily known experimental pressure data of $C_2H_4$ gas. The temperatures examined was 50, 100 and $150^{\circ}C$ and the densities were up to $0.02/{\AA}^3$ (maximum pressure = 1500 atm). The radial distribution function expression used was derived by Yoon, Hacura, and Baglin (YHB) with Baker and Henderson's perturbation theory. The calculated results by a computer showed that the $C_2H_4$ pressures calculated agreed well with the experimental values within ${\pm}5%$ of error range. This indicated that the YHB radial distribution function expression is good enough to obtain various physical quantities sensitive to density such as pressure with resonable accuracy.

• Spatial Information Research
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• v.19 no.1
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• pp.13-19
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• 2011

As an urbanization is in progress, the change of the planimetric features and topography including high-rise residential buildings commonly occur. The change of the planimetric features and topography causes occurrence of the strong wind and wind speed increase or decrease due to the effect of planimetric features and topography on the windward side even though the wind blows with the same speed. In the design standard, this change by wind speed is defined as the velocity pressure exposure coefficient, the value of coefficient is estimated and reflected by ground surface roughness, but in a reality, ground surface roughness is determined in accordance with the subjective judgement of designer and then the velocity pressure exposure coefficient is estimated, moreover the research and data for classification of ground surface roughness are insufficient. In this paper, we will estimate the velocity pressure exposure coefficient by the quantified method for classifying ground surface roughness by using GIS according to the height of a building targeting area where high-rise residential buildings are built lately. When the structure subjected to wind load is designed, reasonability of design and safety of structure will be more improved by using the estimation method of velocity pressure exposure coefficient presented in this study.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.411-423
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• 2002

Accurate and real time forecasting of runoff has a high priority in the drainage basins prone to short, high intensity rainfall events causing flash floods. To take into account the resolution of hydrological variables within a drainage basin, use of distributed system models is preferred. The Landsat Thematic Mapper(TM) observations enable detailed information on distribution of land cover and other related factors within a drainage basin and permit the use of distributed system models. This paper describes monitoring technique of rainfall excess by SCS curve number method. The time series maps of rainfall excess were generated for all the storm events to show the spatiotemporal distribution of rainfall excess within study basin. A combination of the time series maps of rainfall excess with a flow routing technique would simulate the flow hydrograph at the drainage basin outlet.

• The Journal of Engineering Geology
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• v.32 no.2
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• pp.241-255
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• 2022

In this study, sieve analysis testing was performed on weathered granite soil from Yecheon (eastern South Korea) before and after water washing in accordance with the sieve analysis regulations of KS F 2302. The changes in particle separation and particle size distribution after washing with water were analyzed. Image analysis using an optical microscope revealed that soil particles were separated into smaller particles by water washing. The change in the particle size distribution curve was assessed using five index values. The increase in the fine particle fraction (<0.075 mm) was 13.67%, the increase in the 0.075-0.25 mm fraction was 19.44%, and the mean particle diameter (D₅₀) decreased by 0.663 mm. In addition, the maximum passage width (B_M) of the particle size distribution curve increased by 21.08% for the #30 sieve, and the moving area (A) of the particle size distribution curve was 69.28%·mm. These results suggest that washing with water is an effective way to prevent underestimation of the fine particle content in soil.

• Korean Journal of Plant Resources
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• v.30 no.2
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• pp.167-175
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• 2017

We conducted a total of 28 surveys from March to October 2016 in Gayasan National Park, to identify threatened plants for climate change, as well as for the effective management of biological organisms and resources against climate changes in Korea. Regarding threatened plants for climate change, we identified a total of 39 taxa, with 11 northern, 2 southern, and 26 taxa of concern. Among these taxa, 33 were identified as wild species. The species threatened by climate change located in the subalpine regions of Gayasan National Park were Abies holophylla Maxim., Abies koreana Wilson, Pinus koraiensis Siebold & Zucc., Betula ermanii Cham., Berberis amurensis Rupr., Rhododendron tschonoskii Maxim., Vaccinium hirtum var. koreanum (Nakai) Kitam., Primula modesta var. hannasanensis T.Yamaz., Trientalis europaea var. arctica (Fisch.) Ledeb., Thymus quinquecostatus Celak., Parasenecio firmus (Kom.) Y.L.Chen, and Lilium cernuum Kom. These species are expected to be particularly vulnerable to the effects of global warming, since they were confirmed to have a very narrow vertical distribution range. Moreover, although the following species are not included in the list of plants threatened by climate change, it is assumed that the endemic species that grow at the summit, and Grade V floristics special plants, such as Pedicularis hallaisanensis Hurus., Allium thunbergii var. deltoides (S.O.Yu, S.Lee & W.Lee) H.J.Choi & B.U.Oh, Heloniopsis tubiflora Fuse, N.S.Lee & M.N. Tamura, Aletris glabra Bureau & Franch, and Gymnadenia cucullata (L.) Rich., will also be extremely vulnerable to climate change. Therefore, we believe that measures for the conservation of these species are urgently needed, and also that the definition of species threatened by climate change should be broadened to include more objective and valid taxa through the long-term monitoring of species distributed around the summit area.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1737-1741
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• 2007

Using kinematic wave equation, the influence of moving rainstorms to runoff was analysised with a focus on watershed shapes and rainfall distribution types. Watershed shapes used are the oblong, square and elongated shape, and the distribution types of moving storms used are uniform, advanced and intermediate type. The runoff hydrographs according to the rainfall distribution types were simulated and the characteristics were explored for the storms moving down, up and cross the watershed with various velocity. And the hydrographs were compared in the case of varing the rainstorm intensity and varing the rainstorm length in order to make the same total runoff volume. When the rainstorm intensity was varied the shape, peak time and peak runoff of a runoff hydrograph are significantly influenced by spatial and temporal variability in rainfall and watershed shapes. The peak time of down and upstream moving strorms appeared latest in the case of the elongated shape basin, meanwhile at cross stream moving storms, the peak time of elongated shape basin is earlier than the others. For storms moving downstream peak time was more delayed than for other storm direction in the case of elongated watershed. The runoff volume and time base of the hydrograph decreased with the increasing storm speed.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.981-981
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• 2012

최근 지구환경 변화에 따른 기후변화의 영향으로 자연재해의 형태는 점차 대형화, 다양화되고 있으며 극치사상의 발생 빈도가 계속해서 증가하고 있는 추세이다. 특히 도시하천의 경우 인구와 재산이 밀집해 있어 기후변화에 따른 홍수위험 및 취약성이 클 것으로 사료된다. 본 연구에서는 기후 변화에 따른 홍수위험 및 취약성 분석을 위하여 위험도 기반 불확실성을 다루는 수단으로 UQR-MCS (Upper Quartile Range-Monte Carlo Simulation)을 적용하였으며, 다양한 형태의 확률 분포로부터 특정변량(variable)의 확률분포 Quartile을 모의하였다. 또한 기후변화에 따른 도시하천의 홍수위험 및 취약성 평가를 위하여 도시하천에 적합한 홍수위험 및 취약성평가 지수(FVI: flood vulnerability index)를 산정하였으며, 홍수취약성지수는 기후변화(Climate change)와 도시화(Urbanization), 제방월류위험(Overtopping risk) 및 홍수범람 면적(Flood area) 등의 지표를 사용하였다. 각각의 지표는 엔트로피(Entropy) 기법을 적용하여 가중치를 부여하였으며, 표준화과정을 통한 일반화된 지표 값을 산정하였다. 우이천 유역의 기후변화에 따른 홍수위험 및 취약성 지표값은 KMA RCM A1B 시나리오자료를 바탕으로 추정한 미래 확률강수량과 각 인자별 재현기간에 따른 수문변량의 변화를 통하여 산정하였다. 본 연구의 결과는 향후 도시하천의 기후변화에 따른 홍수위험도분석 및 취약성 평가, 극치 수문사상에 대한 신뢰성 있는 분석과 더불어 예상치 못할 이상홍수에 대비한 하천방재 연구에 도움이 되리라 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.368-368
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• 2021

기후 변화로 인한 극한사상의 크기와 빈도 변화를 예측하는 것은 수공 인프라 설계에 있어 주된 관심사 중 하나이다. 보통 극한사상에 대한 강도, 빈도, 지속시간에 대한 정보가 필요하며, 이는 일반적으로 IDF(Intensity-Duration-Frequency) 곡선으로부터 추출된다. 최근 CMIP(Coupled Model Intercomparison Project) 6단계에서 새로운 이산화탄소 배출 시나리오와 업데이트된 기후모델을 이용하여 미래의 기후에 대한 예측 시계열을 발표했으므로, 미래 기후 변화 시나리오를 기반으로 IDF 곡선을 새로 추정하고 미래 기간의 변화를 평가할 필요가 있다. 본 연구에서는 한국의 40개 지역에 대해 일단위 자료를 시단위로 축소(downscaling)한 후, 확률론적 일기생성기(stochastic weather generator)를 이용하여 30년 시단위 시계열을 100개의 앙상블로 생성하였다. 생성된 시계열로부터 연최대강수량 시계열을 재구성하여 GEV 분포와 gumbel 분포에 적용하였다. 적합도 검정(Anderson-Darling(AD) 검정 및 Kolmogorov-Smirnov(KS) 검정)을 수행하였으며, 과거 자료를 기반으로 생성된 IDF 곡선과 비교 검증하였다. CMIP5의 기후변화 자료를 사용한 결과와 CMIP6 기후변화의 결과를 비교하였으며, 본 연구의 주요 결과는 다음과 같다. (1) 향후 강우 강도는 증가할 것이며 강우 강도의 증가는 말기에 현저하게 관찰될 것이다. (2) 시간별 강우 강도의 미래 변화가 일단위 강우 강도보다 더 크다. (3) 강우 강도의 불확실성을 정량화하기 위해 앙상블을 사용해야 한다. (4) 강우 강도의 미래 변화에 대한 공간적인 경향이 확인된다. 시단위 시계열 앙상블을 생성하여 추정된 IDF 곡선에 대한 정보는 기후 변화의 영향을 평가하고 적절한 적응 및 대응 전략을 개발하는 데 도움이 될 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.683-685
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• 2012

This paper have presented the analysis of the change for threshold voltage and drain induced barrier lowering among short channel effects occurred in subthreshold region for double gate(DG) MOSFET with two gates to be next-generation devices, based on scaling theory. To obtain the analytical solution of Poisson's equation, Gaussian function been used as carrier distribution to analyze closely for experimental results, and the threshold characteristics have been analyzed for device parameters such as channel thickness and doping concentration and projected range and standard projected deviation of Gaussian function. Since this potential model has been verified in the previous papers, we have used this model to analyze the threshold chatacteristics. As a result to apply scaling theory, we know the threshold voltage and drain induced barrier lowering is changed, and the deviation rate is changed for device parameters for DGMOSFET.