• 천문학회보
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• 제36권2호
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• pp.90.1-90.1
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• 2011

We are developing empirical space weather (geomagnetic storms, solar proton events, and solar flares) forecast models based on solar information. These models have been set up with the concept of probabilistic forecast using historical events. Major findings can be summarized as follows. First, we present a concept of storm probability map depending on CME parameters (speed and location). Second, we suggested a new geoeffective CME parameter, earthward direction parameter, directly observable from coronagraph observations, and demonstrated its importance in terms of the forecast of geomagnetic storms. Third, the importance of solar magnetic field orientation for storm occurrence was examined. Fourth, the relationship among coronal hole-CIR-storm relationship has been investigated, Fifth, the CIR forecast based on coronal hole information is possible but the storm forecast is challenging. Sixth, a new solar proton event (flux, strength, and rise time) forecast method depending on flare parameters (flare strength, duration, and longitude) as well as CME parameter (speed, angular width, and longitude) has been suggested. Seventh, we are examining the rates and probability of solar flares depending on sunspot McIntosh classification and its area change (as a proxy of flux change). Our results show that flux emergence greatly enhances the flare probability, about two times for flare productive sunspot regions.

• 한국수자원학회논문집
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• 제37권5호
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• pp.437-448
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• 2004

수문학 교과서를 통해 널리 알려진 기존의 유역중심 DAD 분석방법은 유역면적이 작거나 호우이동이 거의 없는 경우에 매우 유용한 방법으로 계산이 비교적 간단하다. 그러나, 태풍과 같이 호우이동이 뚜렷한 경우에는 DAD 관계를 명확히 표현하기 어려우며, 특히 유역면적이 증가함에 따라 평균면적강우량의 오차도 증가하므로, 분석자의 혼란을 야기시킬 수 있다. 이에 본 연구에서는 기존의 유역중심 DAD 분석방법의 단점을 보완코저 호우중실 DAD 분석방법을 개발하였고, 객관적인 DAD 분석결과를 얻기 위해 이를 프로그램화하였다. 관측강우량을 이용하여 기존의 방법과 비교ㆍ검토를 수행한 결과 제안된 방법이 평균면적강우량을 보다 적절하게 표현함을 알 수 있었다. 따라서 개발된 프로그램을 이용하여 우리나라의 전국단위 호우분석(1969년부터 1999년까지 약 130여개 호우)을 수행하였으며, 그 결과를 유역중심 DAD 분석결과와 비교ㆍ검토하였다.

• Membrane and Water Treatment
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• 제10권1호
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• pp.45-55
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• 2019

Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt's test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.

• 한국물환경학회지
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• 제26권5호
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• pp.860-870
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• 2010

Long term monthly monitoring data showed that the water quality of streams flowing into Lake Paldang has been improved by various strategy for water. However, the effect of quality on Lake Paldang is still insufficient because of nonpoint source from watershed. In order to evaluate quantifying methods for pollution source and make a suggestion on improvements, Storm Water Management Model (SWMM) was constructed by using data set from the water quality and streamflow monitoring network in the Kyoungan watershed for Total Maximum Daily Loads (TMDLs). Load duration curve (LDC) based on the result of the Kyoungan watershed SWMM indicated that the water quality criterion on $BOD_5$ was often exceeded in up-stream than down-stream. From flowrate-load correlation curve, SS load significantly increased as streamflow increases. 75.3% of streamflow and 62.1% of $BOD_5$ loads is discharged especially in the zone of high flows, but monitoring data set didn't provide proper information about the conditions and the patterns associated with storm events. Therefore, it is necessary to acquire representative data set for comparing hydrograph and pollutograph through monitoring experimental watershed and to establish methods for quantifying point and nonpoint source pollutant loads.

• 한국해안·해양공학회논문집
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• 제26권6호
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• pp.388-396
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• 2014

본 연구에서는 태풍 매미에 의해 큰 피해를 입은 마산지역을 대상으로 폭풍해일과 강우에 의한 범람 수치모의를 수행하였다. 이를 위해 폭풍해일-강우-우수관망 결합 수치모형을 사용하였다. 그 결과, 기존의 폭풍해일만을 이용하였을 경우보다 강우와 우수관망 수치모형을 고려하였을 때의 침수면적 및 침수고가 크게 증가한 것을 확인하였다. 또한 마산시에서 추진 중인 방재언덕을 설치하였을 때의 침수범람결과를 추가적으로 수치모의 하여 방재언덕의 실효성을 검토하였다. 그 결과 방재언덕의 영향으로 폭풍해일에 의한 최대 침수심은 저감되었으나, 우수가지상부에서 바다로 원활하게 배수되지 못해 침수지속기간이 증가하는 것을 확인하였다.

• 대한토목학회논문집
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• 제26권1B호
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• pp.69-78
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• 2006

제반 수문학적 문제 해결을 위하여 강우사상에 대해 최대평균우량깊이-유역면적-지속기간 관계곡선을 작성하고 있다. 본 연구에서는 상기 관계곡선의 항목 중 최대평균우량깊이를 가뭄심도의 항으로 대체한 가뭄심도-영향면적-지속기간 관계 곡선의 작성방법을 제시하고자 한다. 우리나라 전역의 기상청 월 강수량 자료로부터 산정된 SPI 가뭄지수는 EOF 기법을 이용하여 핵심적인 공간정보로 축약되며, 이를 다시 Kriging 기법을 이용하여 우리나라 전역에 대해 $6km{\times}6km$의 해상도를 가진 SPI 값으로 할당하였다. 격자기반의 가뭄지수 자료의 시간적 분포특성과 공간특성이 고려된 주요 가뭄사상을 식별한 후, 이를 분석하여 최종적으로 영향면적별 지속시간별 가뭄지수가 산정된다. 이에 따라 가뭄심도-가뭄면적-가뭄지속기간 관계곡선이 도시된다. 우리나라 전역에 대한 곡선 작성 결과, 지속기간이 짧고 영향면적이 작을수록 가뭄심도가 깊어지며 영향면적이 증가할수록 가뭄심도가 낮아진다는 면에서는 강우분석시와 비슷한 모양을 보여준다고 할 수 있으나, 가뭄심도의 면적에 따른 감소율은 가뭄분석시의 강우깊이의 면적에 따른 감소율보다 훨씬 작은 것으로 나타났다.

• Journal of Astronomy and Space Sciences
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• 제37권1호
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• pp.19-27
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• 2020

Pc1 pulsations are important to consider for the interpretation of wave-particle interactions in the Earth's magnetosphere. In fact, the wave properties of these pulsations change dynamically when they propagate from the source region in the space to the ground. A detailed study of the wave features can help understanding their time evolution mechanisms. In this study, we statistically analyzed Pc1 pulsations observed by a Bohyunsan (BOH) magneto-impedance (MI) sensor located in Korea (L = 1.3) for ~one solar cycle (November 2009-August 2018). In particular, we investigated the temporal occurrence ratio of Pc1 pulsations (considering seasonal, diurnal, and annual variations in the solar cycle), their wave properties (e.g., duration, peak frequency, and bandwidth), and their relationship with geomagnetic activities by considering the Kp and Dst indices in correspondence of the Pc1 pulsation events. We found that the Pc1 waves frequently occurred in March in the dawn (1-3 magnetic local time (MLT)) sector, during the declining phase of the solar cycle. They generally continued for 2-5 minutes, reaching a peak frequency of ~0.9 Hz. Finally, most of the pulsations have strong dependence on the geomagnetic storm and observed during the early recovery phase of the geomagnetic storm.

• 한국환경과학회지
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• 제10권3호
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• pp.217-223
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• 2001

Where no records are available at a site, a preliminary estimate may be made from relations between floods and catchment chatacteristics. A number of these chatacteristics were chosen for testing and were measured for those catchments where mean annual flood estimates were available. Although the improvement using extended data in regression of flood estimates on catchment characteristics was small, this may be due to the limitations of the regression model. When an individual short term record is to be extended, more detailed attention can be given; an example is presented of the technique which should be adopted in practice, particularly when a short term record covers a period which is known to be biassed. A method of extending the peaks over a threshold series is presented with a numerical example. The extension of records directly from rainfall by means of a conceptual model is discussed, although the application of such methods is likely to be limited by lack of recording raingauge information. Methods of combining information from various sources are discussed in terms of information from catchment characteristics supplemented by records. but are generally applicable to different sources of information. The application of this technique to estimating the probable maximum flood requires more conservative assumptions about the antecedent condition, storm profile and unit hydrograph. It is suggested that the profile and catchment wetness index at the start of the design duration should be based on the assumption that the estimated maximum rainfall occurs in all durations centered on the storm peak.

• 한국물환경학회지
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• 제30권1호
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• pp.8-15
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• 2014

In this study, regression equation was analyzed to estimate non-point source (NPS) pollutant loads in orchard area. Many factors affecting the runoff of NPS pollutant as precipitation, storm duration time, antecedent dry weather period, total runoff density, average storm intensity and average runoff intensity were used as independent variables, NPS pollutant was used as a dependent variable to estimate multiple regression equation. Based on the real measurement data from 2008 to 2012, we performed correlation analysis among the environmental variables related to the rainfall NPS pollutant runoff. Significance test was confirmed that T-P ($R^2=0.89$) and BOD ($R^2=0.79$) showed the highest similarity with the estimated regression equations according to the NPS pollutant followed by SS and T-N with good similarity ($R^2$ >0.5). In the case of regression equation to estimate the NPS pollutant loads, regression equations of multiplied independent variables by exponential function and the logarithmic function model represented optimum with the experimented value.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권1호
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• pp.50-59
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• 2022

There are several methods for separating the baseflow from the hydrograph, and graphical methods (GM) have mostly been used. GMs are those that separate the baseflow from the direct flow simply by connecting rising point with inflection point or points related to some duration from a hydrograph. Environmental tracer method (ETM) is another tool researched and developed under several conditions to estimate the groundwater recharge. The goal of this study is to separate the baseflow component from a storm hydrograph by applying various GMs and ETM, and to compare their results. The baseflow component estimated by ETM was different from the results by GMs in terms of their shapes of fluctuation and flow rates. Another important feature is that the form of the baseflow to which ETM is applied is similar to that of a storm hydrograph. This similarity is presumed to be due to the selection of tracer that respond quickly to rainfall.