• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.164-164
• /
• 2016

Radar rainfall estimates have been widely used in calculating rainfall amount approximately and predicting flood risks. The radar rainfall estimates have a number of error sources such as beam blockage and ground clutter hinder their applications to hydrological flood forecasting. Moreover, it has been reported in paper that those errors are inter-correlated spatially and temporally. Therefore, in the current study, we tested influence about spatio-temporal errors in radar rainfall estimates. Spatio-temporal errors were simulated through a stochastic simulation model, called Multivariate Autoregressive (MAR). For runoff simulation, the Nam River basin in South Korea was used with the distributed rainfall-runoff model, Vflo. The results indicated that spatio-temporal dependent errors caused much higher variations in peak discharge than spatial dependent errors. To further investigate the effect of the magnitude of time correlation among radar errors, different magnitudes of temporal correlations were employed during the rainfall-runoff simulation. The results indicated that strong correlation caused a higher variation in peak discharge. This concluded that the effects on reducing temporal and spatial correlation must be taken in addition to correcting the biases in radar rainfall estimates. Acknowledgements This research was supported by a grant from a Strategic Research Project (Development of Flood Warning and Snowfall Estimation Platform Using Hydrological Radars), which was funded by the Korea Institute of Construction Technology.

• 한국수산과학회지
• /
• 제46권1호
• /
• pp.59-69
• /
• 2013

Temporal and spatial variation in the freshwater region, created by river runoff, of a small bay, caused by the passage of typhoons was examined using a three-dimensional primitive equation model (the Princeton Ocean Model, POM). Numerical experiments were implemented focusing on temporal evolution in the freshwater region in association with typhoon tracks. The model domain covered most of the estuary around the Nakdong River, including Noksan Bay, where river water is periodically released from upstream (Noksan dam). The model showed that the extension of the freshwater region outside of the bay depended strongly on the tracks of typhoons, specifically the associated wind directions and inner flow fields that are accompanied by new clockwise eddies. The model also showed that entrainment from typhoon passage frequently creates salt wedges in the estuary, indicating that organisms in the bay are biologically and chemically influenced with variation in the freshwater region.

• 생태와환경
• /
• 제41권3호
• /
• pp.374-381
• /
• 2008

2005년 10월부터 2006년 8월까지 청계천에서 어류상과 어류군집을 조사한 결과, 채집된 어류는 총 6과 19종이었으며 이중 한국고유종에 속하는 종은 줄납자루, 참갈겨니 등 2종(10.5%)이었다. 조사지점별 어류 발생은 Site 1에서 2과 7종 58개체, Site 2에서 3과 9종 53개체, Site 3에서 4과 9종 282개체, Site 4에서 5과 13종 293개체가 출현하였으며, 지점별 우점종은 버들치(Site 1)와 피라미(Site 2, 3, 4)이었다. 미소서식지가 잘 발달된 하류지점 Site 4에서 종다양도 지수, 종풍부도 지수가 다른 지점에 비해 조사시기 동안 고르고 높게 나타나 다른 조사지점에 비해 비교적 안정적인 어류군집을 형성하였다. 또한 비모수다차원척도법(NMDS)를 이용한 어류군집의 시공간분석을 실시한 결과 어류군집은 하류에서 높은 종풍부도를 보여 장소에 따른 차이를 보였으며, 또한 종풍부도 및 종다양도가 조사 후반부에 가장 높게 나타나 어류군집의 시간적 변동을 구분해 줌으로써 청계천 복원 공사 후 어류군집이 형성되고 점차 안정화되어 가고 있는 것을 반영해 주었다.

• 한국어류학회지
• /
• 제26권1호
• /
• pp.42-49
• /
• 2014

조사기간 동안 총 4종의 부유성 어란과 24종의 자치어가 마산만에서 채집되었다. 어란의 우점종은 멸치 (Engraulis japonicus) 어란이었다. 그러나 자치어는 앞동갈베도라치 (Omobranchus elegan), 고등어 (Scomber japonicus), 문절망둑 (Acanthogobius flavimanus), 쥐노래미 (Hexagrammos otakii), 돛양태류 (Repomucenus sp.), Scartella cristata, 망둥어과(Gobiidae sp.) 순으로 우점하였다. 이들 7종은 전체 출현개체수의 78.5%를 차지하였다. 어란과 자치어는 시공간적으로 큰 변동을 보였다. 어란과 자치어의 현존량은 2007년 7월에 가장 높았으며, 2007년 2월에 가장 낮았다. 그리고 난자치어는 다른 정점에 비해 정점 5에서 현존량이 높았다. 어란과 자치어 현존량의 시간적 변화는 수온에 영향을 받았다. 부유성 어란과 자치어는 수심, 지형 등과 같은 물리적 환경 요인에 따라 좀 더 얕은 만 안쪽 정점과 깊은 만 외곽 정점 간 군집 차이를 보였다.

• 한국정보통신학회논문지
• /
• 제11권11호
• /
• pp.2172-2178
• /
• 2007

실내 환경에서 이러한 두가지변수인 대규모에서의 경로손실과 소규모에서의 페이딩현상은 거리에 대한 RSSI(Received Signal Strength Indicator) 값의 비선형적인 변화를 유발하게 되며 이러한 현상이 실내위치 추적에서의 문제점의 하나로 지적되고 있다. 이 연구에서는 동일한 방에서의 다른 위치와 시간에서의 RSSI변화를 실험에 의한 통계에 의해 찾아서 보다 정밀한 모델을 세워서 실내 RSSI 특성화를 이루려고 하였다. 실험에서 RSSI값이 공간과 일시적인 요인 두가지에 의해 결정되는 것이 확인되었고 다른 위치에 있는 모든 센서 노드도 공간차라메터는 다르지만 임시파라메터값은 동일하다는 것을 확인하였다. 임시 파라메터들도 환경변화에 따라 천천히 신간에 따라 변화하는 대규모적인 변수의 특성을 지닌다. 이러한 관계를 활용하여 위치추적을 보다 효율적이고 정밀하게 평가할 수 있었다.

• Spatial Information Research
• /
• 제7권1호
• /
• pp.39-48
• /
• 1999

격자 물수지 기법을 이용하여 일단위 토양수분변화를 추적할 수 있는 분포형 토양수분추적모형을 개발하였다. 본 모형은 C-언어로 구성하여 다양한 GIS 소프트웨어들을 수용할 수 있도록 유연성을 확보하였다. 전처리 과정으로서 래스터 GIS 소프트웨어인 GRASS를 이용하여 모형에 필요한 자료를 준비하고 후처리과정으로서 모형의 결과를 GRASS상에서 도시할 수 있도록 구성하였다. 개발된 모형의 적용성을 검토하기 위하여 보청천 유역의 일부인 이평교 유역(75.6㎢)을 대상으로 이평교 지점에서의 실측 일유출량과 모형에 의한 모의발생치를 비교하였으며, 출력결과로서 월별로 정리된 토양수분 분포도를 GRASS상에 작성하여 예시하였다.

• Journal of applied mathematics & informatics
• /
• 제27권1_2호
• /
• pp.385-400
• /
• 2009

The adverse effect of harmful plankton on the marine ecosystem is a topic of deep concern. To investigate the role of such phytoplankton, a mathematical model containing distinct dynamical equations for toxic and non-toxic phytoplankton is analyzed. Stability analysis of the resulting three equation model is carried out. A continuous time variation in toxin liberation process is incorporated into the model and a stability analysis of the resulting delay model is performed. The distributed delay model is then extended to include the spatial distribution of plankton and the delay-diffusion model is analyzed with spatial and spatiotemporal kernels. Conditions for diffusion-driven instability in both the cases are derived and compared to explore the significance of these kernels. Numerical studies are performed to justify analytical findings.

• 한국환경과학회지
• /
• 제19권6호
• /
• pp.761-769
• /
• 2010

Temporal trends of ozone concentration in Jinju were investigated by using observation data from 3 air quality monitoring stations for the period of 2004~2008. In addition, spatial comparisons of ozone concentration at Jeoguri, upwind and downwind directions of Jinju were investigated between May and September 2009. Annual mean exhibited increasing trends +1.7ppb/yr throughout the study period. In the case of diurnal variation, the lowest ozone concentration was shown from 7 am to 8 am and the highest around 4 pm. The ozone concentrations of Jeoguri station of the south coast were higher than Jinju. In particular, the upwind direction of Jinju had relatively hight ozone concentration

• ALGAE
• /
• 제27권2호
• /
• pp.109-114
• /
• 2012

Water motion is one of the main drivers in morphological variability in species within de order Laminariales, and most of our current knowledge is based on subtidal populations. $Eisenia$ $arborea$ is a dominant kelp species in the North Pacific, widely distributed along the Baja California Peninsula from mid intertidal down to subtidal areas. This species presents great variability in the intertidal zone but it has not been yet evaluated such variability according to wave exposure. The present work also identifies the spatial / temporal variation, particularly respect to the presence of stipes without medulla (hollow stipes) a feature common among other brown seaweeds. We evaluated the effects of wave action in morphological variation of intertidal $Eisenia$ $arborea$ (Laminariales, Ochrophyta) at Punta Eugenia. The spatial and temporal variation sampling was surveyed between February, May, July, and August 2004 in the intertidal of Punta Eugenia, Baja California Sur. Our results have shown that exposed sites correlate with increased length and width of stipes as compared to more protected sites. Hollow stipes frequency changed more in association with temporal variation than with spatial heterogeneity suggesting nutrient limitation for thalli development. Our results suggest that $Eisenia$ $arborea$ compensate by morphological modifications the stress of living in the intertidal zone by showing larger stipes. Hollow stipes might be are also a mechanical adaptation to increase survival in high energy environments.

• Environmental Engineering Research
• /
• 제20권1호
• /
• pp.19-24
• /
• 2015

This paper mainly focuses on the research of the monitoring data about the total nitrogen (TN), total phosphorus (TP) of ten monitoring points of Hongze Lake in 28 years. Our study adopts the technical methods such as difference comparison, correlation analysis, Mann-Kendall, etc. to analyze the statistical characteristics, regional differences, and temporal and spatial variation condition of ten monitoring points of Hongze Lake in 1986-2013 as well as the reason for the time and space variation of TN and TP. The results show that the TN and TP of Hongze Lake change dramatically during the period of 1994-2004. In all the monitoring periods, TN and TP of the HZ5, HZ6, HZ7, HZ8 monitoring points in the estuary surrounding the Huaihe River are the highest, which suggests that TN and TP of Hongze Lake should not be ignored for the pollution along the Huaihe River. The TN concentration in the core area is the highest, but that in the development control area is the lowest. In most of the years, TN concentration is higher than 2 mg/L, and the water quality is V class and poor V class water quality in China's Environmental Quality Standards for Surface Water (GB3838-2002). TP concentration of the three areas is basically close, that is lower than 2 mg/L in most of the years, and the water quality is within the V class. The TN and TP concentration of Hongze Lake decreased and intensifying trend of eutrophication is controlled after 2004.