• 대기
• /
• 제27권4호
• /
• pp.455-466
• /
• 2017

In Korea, property and human damages occur annually due to heavy precipitation during the summer. On August 8, 2015, heavy rainfall occurred in the Seoul metropolitan area due to an outflow boundary, and $77mmhr^{-1}$ rainfall was recorded in Gwangju, Gyeonggi Province. In this study, the simulation of the WRF numerical model is performed to understand the cause and characteristics of heavy rainfall using the Conditional Instability of the Second Kind (CISK), potential vorticity (PV), frontogenesis function, and convective available potential energy (CAPE) analyses, etc. Convective cells initiated over the Shandong Peninsula and located on the downwind side of an upper level trough. Large amounts of water vapor were supplied to the Shandong Peninsula along the southwestern edge of a high pressure system, and from the remnants of typhoon Soudelor. The mesoscale convective system (MCS) developed through CISK process and moved over to the Yellow Sea. The outflow boundary from the MCS progressed east and pushed cold pool eastward. The warm and humid air over the Korean Peninsula further enhanced convective development. As a result, a new MCS developed rapidly over land. Because of the latent heat release due to convection and precipitation, strong potential vorticity was generated in the lower atmosphere. The rapid development of MCS and the heavy rainfall occurred in an area where the CAPE value was greater than $1300Jkg^{-1}$ and the fronto-genesis function value of 1.5 or greater coincided. The analysis result shows that the MCS driven by an outflow boundary can be identified using CISK process.

• 한국방재학회 논문집
• /
• 제3권2호
• /
• pp.111-118
• /
• 2003

건설중인 경부고속철도에서는 열차의 운행안전을 확보하기 위하여 다양한 안정시스템을 채택하고 있어 예기치 못한 재해발생으로 인한 인적 물적 피해의 최소화에 만전을 기하고 있으나, 국외규정이 도입되는 과정에서 국내 선로, 기후, 지형 지질학적 특성을 반영한 국내규정으로는 정립되어 있지 않은 현실이다. 따라서, 본 연구에서는 강우시 고속철도의 안전한 운행을 위해 현재 설정되어 운용 예정인 강우시 운전규제를 위한 경계우량의 문제점을 파악하고 보완함으로써 보다 합리적인 경계우량의 재설정이 가능하였다. 또한, 이를 이용하여 CTC 등의 중앙통제기구에서 정상운행 경계발령 열차속도규제 운전정지의 4단계로 강우상황에 따라 열차의 안전을 명확하게 확보할 수 있을 것이며, 자연재해 발생 최소화에 기여할 수 있을 것이라 판단된다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.397-402
• /
• 2003

Infiltration of rainfall causes railway embankment to be unstable and may result in failure. Basic relationship between the rainfall and stability of railway embankment are defined to analyze the stability of embankment by rainfall. An experimental study for defining of infiltration rate of rainfall into slope is conducted in the lab. The results of Rainfall infiltration show that rainfall infiltration is not equal to infiltration as like reservoir because rate of rainfall infiltration is controlled by slope angle. Based on these results, boundary condition of rainfall is altered and various numerical analysis are performed. The variation of shear strength, the degree of saturation and pore-water pressure for railway slope during rainfall can be predicted and the safety factor of railway slope can be expressed as the function of rainfall amount, namely rainfall index. Therefore, it is judged that this rainfall index can be a good tool for the rail-transport operation control.

• 한국농공학회지
• /
• 제11권3호
• /
• pp.1742-1748
• /
• 1969

This is a method to determine the boundary line of reservoir flooding area which will be purchased. Until now, flood water level was used as the boundary line. By lowering this line from flood water level, purchasing cost of reservoir flooding area can be cut down. Sometimes, temporary flooding of arable land outside the boundary occurs. During the life of reservoir, flood damage to crop product on of this land must be indemified with net berefit from arable land between the bovndary line and normal water level. Following is the basic formula to determine the line. (Estimated flood damage to crop production of land outside the boundary line $\leqq$ Estimated net beneift from land between the boundary line and normal water level.) Minimum difference between both sides is needed to minimize the purchasing area. Flood damage and net benefit are estimated by hydrologic estimation with rainfall data and crop production estimation.

• 대기
• /
• 제22권4호
• /
• pp.387-400
• /
• 2012

This study aims at examining the sensitivity of numerical simulations to the resolution of initial and boundary data, and to an application of WRF (Weather Research and Forecasting) 3DVAR (Three Dimension Variational data Assimilation). To do this, we ran the WRF model by using GDAS (Global Data Assimilation System) FNL (Final analyses) and the KLAPS (Korea Local Analysis and Prediction System) analyses as the WRF's initial and boundary data, and by using an initial field made by assimilating the radar data to the KLAPS analyses. For the sensitivity experiment, we selected a heavy rainfall case of 21 September 2010, where there was localized torrential rain, which was recorded as 259.5 mm precipitation in a day at Seoul. The result of the simulation using the FNL as initial and boundary data (FNL exp) showed that the localized heavy rainfall area was not accurately simulated and that the simulated amount of precipitation was about 4% of the observed accumulated precipitation. That of the simulation using KLAPS analyses as initial and boundary data (KLAPC exp) showed that the localized heavy rainfall area was simulated on the northern area of Seoul-Gyeonggi area, which renders rather difference in location, and that the simulated amount was underestimated as about 6.4% of the precipitation. Finally, that of the simulation using an initial field made by assimilating the radar data to the KLAPS using 3DVAR system (KLAP3D exp) showed that the localized heavy rainfall area was located properly on Seoul-Gyeonggi area, but still the amount itself was underestimated as about 29% of the precipitation. Even though KLAP3D exp still showed an underestimation in the precipitation, it showed the best result among them. Even if it is difficult to generalize the effect of data assimilation by one case, this study showed that the radar data assimilation can somewhat improve the accuracy of the simulated precipitation.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.225-232
• /
• 2009

Infiltration of rainfall causes railway slopes to be unstable and may result in failure. Basic relationship between the rainfall and stability of railway embankment is defined to analyze its stability by rainfall. An experimental study for defining of infiltration rate of rainfall into slope is conducted in the lab. The results of Rainfall infiltration show that rainfall infiltration is not equal to infiltration as like reservoir because rate of rainfall infiltration is controlled by slope angle. Based on these results, boundary condition of rainfall is altered and various numerical analysis are performed. The variation of shear strength, the degree of saturation and pore-water pressure for railway slope during rainfall can be predicted and the safety factor of railway slope can be expressed as the function of rainfall amount, namely rainfall index. And suggested rainfall index is compared with the rail transport operation control which is used in KORAIL. It is judged that this rainfall index can be a good tool for the rail-transport operation control.

• 한국지반공학회논문집
• /
• 제34권5호
• /
• pp.37-51
• /
• 2018

우리나라의 산지사면은 풍화잔류토 층의 깊이가 얕아 강우의 침투로 인한 사면파괴가 많이 발생한다. 이때 파괴면의 깊이는 얕고 토사층과 기반암의 경계면 근처를 통과하는 특징을 가지고 있다. 강우의 침투로 인한 불포화 토사사면의 불안정성에 중요한 영향을 미치는 지반 정수들은 큰 불확실성을 포함한다. 따라서 본 연구에서는 강우로 인한 사면파괴를 예측하기 위하여 지반의 수리학적 특성과 강도특성을 랜덤변수로 고려하는 몬테카를로 시뮬레이션에 의한 확률론적 해석 절차를 제안하였다. 일정한 강우강도에 대한 기반암이 얕게 존재하는 불포화 토사사면의 안정성 예측을 위하여 강우강도에 따른 사면 표면에서의 경계조건을 반영하여 Green-Ampt 모델을 수정하고 얕은 기반암의 경계조건을 도입하였다. 침투해석의 결과를 무한사면 해석에 적용하여 안전율을 계산하였다. 제안된 확률론적 해석법은 강우의 침투에 따른 사면의 시간 의존적 파괴확률을 계산할 수 있다.

• 한국항공운항학회지
• /
• 제22권1호
• /
• pp.76-84
• /
• 2014

Heavy Rainfall event accompanying with Mesoscale Convective Systems(MCSs) inducing flash flooding and Kimpo and Inchon International Airport closing over Seoul metropolitan area was investigated this study. This heavy rainfall event was occurred through the synoptic scale boundary of North Pacific Subtropical high, Typhoon and also can predicted by proper analysis of various forecasting parameters such as abundant moisture, instabilities, and synoptic/mesoscale forcing.

• 대한토목학회논문집
• /
• 제28권3C호
• /
• pp.167-178
• /
• 2008

본 연구에서는 실제 풍화토 사면에 대하여 침투해석과 안정해석을 수행하여 강우에 따른 사면의 붕괴를 재현하였다. 불교란시료를 채취하여 불포화토 물성을 실험적으로 직접 획득하여 실제 강우량에 의하여 침투해석을 수행한 결과, 토사층과 암층의 경계부를 중심으로 간극수압이 증가하는 경향이 나타났다. 또한 안정해석을 수행한 결과 안전율이 1.0미만으로 감소하여 실제 사면의 붕괴를 재현할 수 있었다. 또한 설계 강우강도에 의하여 침투해석을 수행한 결과 선행강우 및 강우기간에 따른 침투효과를 고려하기 곤란하였다. 이로 인하여 토사층의 수두변화가 크게 발생하지 못하였고 사면의 안전율이 1.0이상으로 나타났다. 또 다른 붕괴 사면의 경우에는 불포화토의 정수들을 인공신경망기법으로 추정하였다. 침투해석 결과 토사층과 연암층 경계부를 중심으로 포화대가 뚜렷하게 형성되었으며 이로 인하여 토사층의 안전율이 1.0미만으로 감소하였다. 이러한 기법을 통하여 실제 사면의 붕괴를 재현하는 것이 가능하다고 판단된다.

• 한국지반공학회지:지반
• /
• 제7권1호
• /
• pp.53-68
• /
• 1991

이 논문은 강우가 시작된 후 시간의 경과에 따른 불구화 지반에서의 여러가지 침투거동을 밝혀서, 서면 불안정의 구체적인 머케니즘을 이해하려는데 목적이 있다. 이를 위해 강우장치를 만들어 권쬐요면에 대해 여러가지 강도의 강우를 재현하고 침투거동을 측정하는 한편, 실험에서 사용한 동일한 수치권을 가지고 수치 해석을 하였다. 두가지 모델시 험 의 결과로부터 만윤전선이 진행되는 과정,지반으로 침투되는 한계강우량의 존재,지표류출의 영향,시간의 경과에 따른 간극수압의 변화 등을 밝혀서 이들 인자들이 사면 불안정에 어떻게 영향을 끼치는가를 자세히 언급하였다.