• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.307-314
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• 2000

This study is to investigate the recurrence characteristics of wet and dry years using over 200 year records of annual rainfall depth including Chosun Age in Korea. As well as analyzing the correlation structure of the raw data, recurrence trends of wet and dry year has been investigated based on several truncation levels (mean, $mean{\pm}0.25stdv.,\;mean{\pm}O.5stdv.,\;mean{\pm}O.75stdv.,\;mean{\pm}stdv.$). Also the transition probability among wet, dry and normal years has been derived for the same truncation levels. and finally the average return periods based on the steady-state probabilities were obtained. This analysis has been applied to not only the entire data but also partial data set of before- and after-the long dry period around 1900 in order to compare and detect the possible difference between the Chukwooki (an old raingauge invented in Chosun age) and the modem flip-bucket style. As a result, Similar pattern of dry and wet year recurrence has been found, but the return period of extremely dry years after the dry period shown longer than that before the dry period. Assuming that the dry and wet years can be defined as $mean{\pm}$ standard deviations, respectively, the return period of the wet years is shown to be about 5~6 years and that of the dry years about 6~7 years.

• Journal of Korea Water Resources Association
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• v.33 no.5
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• pp.519-526
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• 2000

This study is to investigate the recurrence possibility of consecutive dry years such as the long dry period around 1900 in the annual rainfall data at Seoul station. The truncation levels, as the criterion for the dry years, are decided such as to make the occurrence of dry years follow the Poissonian distribution, which assures independent occurrence of dry years. For the truncation level of mean-0.5stdv, the occurrence of dry years is found to satisfy the Poissonian distribution weakly with 99% significance level, but for those of mean-0.75stdv and mean-stdv with 95% significance level. For these truncation levels, the long dry period around 1900 is divided into several short consecutive dry years. The Poisson process has then been applied to derive the occurrence probability of consecutive dry years. For the truncation level of mean-0.75stdv or below, the Poisson process was found to reproduce similar occurrence probabilities to the observed. Especially for the lowest truncation level used in the study (mean-stdv), we could see that the occurrence probability of consecutive dry years estimated for the data collected before the long dry period around 1900 was higher that those for the data collected after the long dry period, thus, it could be concluded that the possibility of long dry periods is decreasing recently.cently.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1551-1554
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• 2009

가뭄은 여러 수문학적 재해유발 요인 중에서 극심한 피해를 유발시키는 자연재해 중의 하나이다. 가뭄은 장기간 동안 계속되어 물순환과정에 악영향을 끼치며 이로 인해 물부족을 유발시켜 농업 등의 산업에 재해를 유발시키고 있는 실정이다. 가뭄은 학문적으로 기상학적, 농업적, 수문학적, 사회 경제적 가뭄으로 구분할 수 있으며 학문적으로 분류된 가뭄은 조건에 따라 가뭄현상의 정의가 약간씩 달라지게 된다. 따라서 본 연구에서는 여러 가뭄지수 중에서 비교적 산정과정이 간단하고 기상학적인 가뭄과 농업적 가뭄을 고려할 수 있는 가뭄지수인 과우일수를 산정하였다. 분석대상 지역은 우리나라의 기상청에서 관할하며 30년 이상 관측된 자료를 이용하였다. 산정된 과우일수의 군집분석을 통해 우리나라 가뭄지역 구분을 수행하였다.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.145-153
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• 2016

Using monthly rainfalls, this study investigated outliers of annual and/or seasonal rainfall for quantitative assessment of historical droughts in Korea. Based on the analysis of annual rainfall, Icheon, Geochang, Jeongeup, Suncheon and Jangheung gaging stations were selected to represent the major river basins, because they had most frequent dry years. The overall results indicated that the years of 1988 and 1994 were the worst dry years. Although the 2001 drought was not severe, it resulted in typical agricultural drought damage mainly in Seomjin and Yeongsan river basin due to the lack of agricultural water. On the other hand, the droughts of 1981-1982 and 1994-1995 were long term nation wide droughts that lasted more than two years resulting in extensive drought damages to parts of the country.

• 베이커리
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• no.9 s.434
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• pp.77-80
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• 2004

• 베이커리
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• no.11 s.448
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• pp.160-161
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• 2005

• Journal of Korea Water Resources Association
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• v.37 no.1
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• pp.13-19
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• 2004

This study shows the possible use of the Poisson process for the characterization of dry year return period and duration. For the analysis we used an annual precipitation data, which has been collected since 1911 in Seoul. The highest threshold for the application of the Poisson process was determined to be the mean-0.5standard deviation, and then the results from the Poisson process are compared with the observed. Especially, the Poisson process was found to reproduce the mean duration and return interval quite well and show the possibility of using the Poisson process for the drought analysis.

• KCID journal
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• v.1 no.2
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• pp.71-73
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• 1994

• KCID journal
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• v.3 no.1
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• pp.20-31
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• 1996

Several drought indices, which indicate the severity of drought in a reservoir or an irrigated area, have been suggested in home and overseas. However, the indices have not been adopted because those were extremely difficult to be understood by the genera

• Journal of the Korean earth science society
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• v.23 no.7
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• pp.587-596
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• 2002

A super ensemble model was developed for the seasonal prediction of regional precipitation in Korea using the lag correlated large scale predictors, based on the empirical orthogonal function (EOF) analysis and multiple linear regression model. The predictability of this model was also evaluated by cross-validation. Correlation between the predicted and the observed value obtained from the super ensemble model showed 0.73 in spring, 0.61 in summer, 0.69 in autumn and 0.75 in winter. The predictability of categorical forecasting was also evaluated based on the three classes such as above normal, near normal and below normal that are clearly defined in terms of a priori specified by threshold values. Categorical forecasting by the super ensemble model has a hit rate with a range from 0.42 to 0.74 in seasonal precipitation.