• Ocean and Polar Research
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• 제30권2호
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• pp.149-158
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• 2008

The characteristic analysis of the estimated population parameters, i.e., standard deviation and error bound of coastal pollutant concentrations (hereafter PC, i.e., COD, TN, and TP concentrations), was carried out by using environmental data with different sampling frequency in Lake Shihwa and Incheon coastal zone. The results clearly show that standard deviation of the PC increases as its mean value increases. The error bounds of the annual mean values based on seasonally measured DO concentrations and PC data in Incheon coastal zone were estimated as ranges 2.26 mg/l, $0.68{\sim}0.86\;mg/l$, $0.62{\sim}0.80\;mg/l$, and $0.074{\sim}0.082\;mg/l$, respectively. In terms of annual mean of the DO concentration and PC in Lake Shihwa, the error bounds based on monthly measured data from 1997 to 2003 were also estimated as ranges 4.0 mg/l, 3.0 mg/l, $0.5{\sim}1.0\;mg/l$, and 0.05 mg/l, respectively. The error bound on the basis of real-time monitoring data is $7{\sim}13%$ only as compared to that of monthly measured data.

• 한국대기환경학회지
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• 제5권1호
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• pp.88-95
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• 1989

The aspects of the occurence frequency of $SO_2$ concentration were studied with the observed data in Seoul and the scheme that is capable of estimating not only highest concentration for a variety of averaging times but also concentrations for arbitary occurrence frequency with long term arithmatic mean and geometric standard deviation data, was evaluated. The results of the statistical analysis show that the occurrence frequency is almost log normal except a few cases, and 3rd highest values of daily mean concentration were about 4.2 $\sim$ 5.2 times higher than annual arithmatic mean. The evaluation with the observed hourly concentration shows that the scheme fairly well estimate the short concentration of arbitary occurrence frequence and it can be used for air quality management and environmental impact assessment.

• Current Research on Agriculture and Life Sciences
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• 제5권
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• pp.143-157
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• 1987

In order to determine the design precipitation, the most probable daily precipitation and annual precipitation at every spot are calculated and iso - precipitation line are drawn. Probability of precipitation and drought phenomena of each gage station are analyzied by the method of frequency analysis from the statistical conceptions. The results summarized in this study are as the follows. 1. Annual mean precipitation in kyungpook area are 1044 mm, about 115 mm less than annual mean precipitation of Korea amounts to l1S9mm, and found to regionally unequal. 2. Monthly mean rainfall of July is 242.2mm, 23.2%, August 174.2mm, 16.7%, June 115mm, 11% and September 114.2mm, 10.9% and Rainfall depth of July-August are more than 40% of annual precipition. This shows notable summer rainy weather by typoon and low pressure storm and seasonal unbalance of water supply. 3. The relation among the maximum precipi.tation per day, per two continuous days and per three contnous days are caculated and the latter is found 31.0% increased rate of the first and the last 48.2% increased rate of first. 4. Probability precipitation in Kyungpook area are shown as 9.0%(5 year), 13.3%(10 year), 17.7%(20 year), 23.1%(50 year), 27.0%(100 year) and 31.1%(200 year) increased rate of each recurrence year compared with observed average annual precipitation. 5. From annual precipitation and maximum daily rainfall data probability of precipitation and precipitation isohyetal line are derived which shown as Table 11 and Fig. 8. 6. Drought days are divided 6 class and analysed results are shown on table 12. Average occurrence time of 10-14 continuous drought days are 2.3 time per year, 15-19 days are 0.9 time per year, 20-24 days are one per six years, 30-34 days are once per nine years and over than 35days are once per 25 years.

• 한국습지학회지
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• 제4권2호
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• pp.43-56
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• 2002

About 12 rain gauge stations of Korea, annual maximum rainfall series of before and after 1980 whose durations are 1, 2, 3, 6, 12, 24, 48, 72 hours respectively were composed and statistical characteristics of those time series were calculated and probability rainfall were estimated by L-moment frequency analysis method and compared each other in order to investigate the recent quantitative rainfall variations. And also, distribution curves of each statistical variations for each duration were constructed by using Kigging method to look into spacial rainfall variation aspects. As a result, We could confirm recent rainfall increase in the South Korea. And spatial increase pattern of standard deviation and frequency rainfall appeared analogously each other. 1n the cases of comparatively short rainfall duration, we could see relatively low increase or decrease tendency in Chungchong Province, Cholla-bukdo, Cholla-namdo eastern part, Kyongsang-namdo western part area. While, variations happened great1y in seaside district of east coast, southwest seashore, Inchon area etc. In the cases of longer durations relatively low increase was showed in southern seashore such as Yeosoo area and as distance recedes from this area, showed gradually augmented tendency. The aspect of mean looks similar tendency of above except that the variation rate of almost seaside district are big in the case of shorter durations. In addition, rainfall increases of short durations which became the center of hydrologist and meteorologist are unconfirmed in this study.

• 한국농공학회논문집
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• 제48권5호
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• pp.17-27
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• 2006

The objective of this study is to induce the design floods by the methodology of L-moment including test of homogeneity, independence and outlier of the data of annual maximum flood flows for 12 water level gaging stations of South Korea. To select appropriate distribution of the data for annual maximum flood flows, the distributions of Wakeby and Kappa are applied and the appropriateness is judged by Kolmogorov-smirnov (K-S) test. The parameters of selected Wakeby and Kappa distributions are calculated by the method of L-moment and the design floods are induced. Through the comparative analysis using the relative root mean square errors (RRMSE) and relative absolute errors (RAE) of design floods, the result shows that the design floods by Wakeby distribution are closer to the observed data than those obtained by the Kappa distribution.

• 한국수자원학회논문집
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• 제49권5호
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• pp.451-458
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• 2016

본 연구에서는 미계측유역에서의 빈도홍수량을 추정하기 위해 지역홍수빈도분석의 표준방법인 지수홍수법을 이용하였다. 이를 위해 충주댐 상류유역을 대상으로 공간확장한 22개 지점의 연최대홍수량 자료을 활용하였으며, 구축된 다지점의 자료계열을 이용하여 지수홍수법의 주요인자인 평균홍수량의 지역화 과정를 수행하였다. 지역화를 위한 방법으로는 홍수량과 유역면적과의 관계가 멱함수 법칙(power law)를 따른다는 이론에 근거한 경험관계를 유도하였다. 충주댐 상류유역 전체를 하나의 그룹, 3개의 중권역을 각각 하나의 그룹으로 구분하여 분석하였다. 도출된 결과에 따르면 평균홍수량과 유역면적과의 관계를 멱함수 법칙으로 설명할 수 있었다. 또한, 미계측 지점의 홍수량 추정시에는 가까운 계측지점 즉, 직상하류 유역의 비유량의 관계를 사용하는 것이 타당함을 증명하였다. 따라서, 미계측 유역을 위한 지역빈도해석은 지역홍수빈도해석 절차 자체도 중요하지만, 지역의 세밀한 구분과 그에 따른 지역화 경험관계 개발과정도 중요한 절차임을 확인할 수 있었다.

• 한국농공학회지
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• 제41권4호
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• pp.25-29
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• 1999

This study was conducted to derive optimal design floods by Gerneralized Extreme Value(GEV) and Weibull-3 distributions for the annual maximum series at ten watersheds along Han,Nagdong, Geum, Yeongsan and Seomjin reiver systems. Adequency for the analysis of flood data used in this study was established by the tests of Independence. Homogeneity , detection of Outlines, L-moments. Design flood sobtaine dby /methods of Moments and L-Moments using different methods for plotting positions in BEV and Weibull-3 distributions were compared by the Relative Mean Errors(RME) and Root MEan Square Errors(RMSE). The result wa found that design floods derived by the L-moments using the other formulas for plotting positions from the viewpoint of Relative Mean Errors and Root Mean Square Errors.

• 한국해안·해양공학회논문집
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• 제27권4호
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• pp.266-273
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• 2015

본 연구에서는 국내 서해안의 해상풍력 발전을 위한 적지를 검토하기 위해 기상청에서 제공하는 6개 지점(서수도, 가대암, 십이동파, 갈매여, 해수서, 지귀도)의 2014년 연간 풍속 자료를 수집하고 이를 분석하였다. 관측된 풍속 자료는 Rayleigh 모델과 Weibull 모델에 적합하였으며, 풍속 출현빈도에 따라 연간 부존량을 추정하였다. 풍력발전기 모델로는 GWE-3kH(3 kW급) 터빈과 GWE-10KU (10 kW급) 터빈을 선정하였으며 이의 성능곡선을 이용하였다. 그 결과, 서수도, 가대암, 십이동파, 갈매여, 해수서, 지귀도의 연평균 풍속은 각각 4.60, 4.5, 5.00, 5.13, 5.51, 5.90 m/s로 나타났으며, 연간 발전량은 10,622.752, 11,313.05, 13,509.41, 14,899.55, 17,106.13, 19,660.85kWh로 나타났다. 6개 지점의 연평균에너지 밀도는 전체적으로 poor와 marginal 계급으로 나타났으며, 터빈 이용률은 지귀도가 22.44%로 가장 높게 나타났다.

• 한국농공학회지
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• 제37권2호
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• pp.31-40
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• 1995

This study was conducted to get best fitting frequency distribution for the annual run- off and to simulate long series of annual flows by single-season first order Markov Model with comparison of statistical parameters which were derived from observed and synthetic flows at four watersheds in Seom Jin and Yeong San river systems. The results summarized through this study are as follows. 1. Hydrologic persistence of observed flows was acknowledged by the correlogram analysis. 2. A normal distribution of the annual runoff for the applied watersheds was confirmed as the best one among others by Kolmogorov-Smirnov test. 3. Statistical parameters were calculated from synthetic flows simulated by normal dis- tribution. In was confirmed that mean and standard deviation of simulated flows are much closer to those of observed data than except coefficient of skewness. 4. Hydrologic persistence between observed flows and synthetic flows simulated was also confirmed by the correlogram analysis. 5. It is to be desired that generation technique of synthetic flow in this study would be compared with other simulation techniques for the objective time series.

• 한국초지조사료학회지
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• 제14권1호
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• pp.50-56
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• 1994

본 시험은 농산물의 수입자유화 추세로 들어가고 있는 유휴 경작지에 조사료 자원확보와 날로 심각하게 증가되는 가축분뇨를 유기질 비료로서 재활용하여 환경보전을 목적으로 유휴 논 토양에 조성된 리드카나리그라스의 초지에 액상구비를 시용하여 연 평균 건물수량과 계절적 분포 및 적정 액상구비의 시용수준을 추정코자 실시되었다. 2. 3개의 예취빈도(연간3, 4및 5회 예취)조건에서 연 평균 건물수량은 ha당 8.9~10.9톤을 기록하였는데 3회 예취 이용시에 가장 높은 건물수량을 나타내었다. 2. 액상구비의 시용은 연간 ha당 300~360kg의 질소수준 이상에서 전혀 비료를 시용하지 않았던 대조구보다 유의한 연 평균 건물수량의 차이를 나타내었다(p=0.05). 3. 연간 3회와 4회 예취 이용한 시험구에서는 액상구비의 시용수준 주 제 1단계(3회 예취구: 90kg N/ha, 4회 예취구: 120kg N/ha/년)에서 이전 수준인 무비구보다 ha당 연간 각각 1.23톤과 2.34톤의 가장 높은 건물수량의 증가를 기록하였고, 5회 예취구에서는 2단계의 액상구비 수준 (300kg N/ha/년)에서 이전 수준(150kg N/ha)보다 2.11톤의 연간 건물 수량의 증가를 초래하였는데, 이들의 질소효율은 각 예취조건 하에서 각각 kg질소당 13.7, 19.4 및 14.1kg의 건물 수량에 해당되었다. 4. 연 건물수량의 계절적 분포는 3회 예취구에서 2번초, 4회 예취구의 3번초 및 5회 예취구의 3번초에 각각 전체의 42.37 및 32%로 가장 높은 비율을 차지하였다. 5. 본 시험조건에서는 5회 예취구에서만 생장곡선이 결정계수 $r^2$=0.9993으로 시그마 형태에 가장 근접하였는데, 이를 이용하면 최고 한계수량은 액상구비의 형태로 연간 ha당 250kg의 질소수준에서 도달하고 경제적 액상구비의 이용수준은 371.0~402.2kg의 질소였으며, 최대수량은 연간 ha당 489.3kg의 액상구비 시용시 얻을 수 있었다.