• 한국환경과학회지
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• 제25권3호
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• pp.345-359
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• 2016

This study analyze the synoptic meteorological cause of rainfall, rainfall intensity, drop size distribution(DSD), fall velocity and oblateness measured by the 2D-Video distrometer(2DVD) by comparing two cases which are heavy rainfall event case and a case that is not classified as heavy rainfall but having more than $30mm\;h^{-1}$ rainrate in July, 2014 at Gimhae region. As a results; Over the high pressure edge area where strong upward motion exists, the convective rain type occurred and near the changma front, convective and frontal rainfall combined rain type occurred. Therefore, rainrate varies based on the synoptic meteorological condition. The most rain drop distribution appeared in the raindrops with diameters between 0.4 mm and 0.6 mm and large particles appeared for the convective rain type since strong upward motion provide favorable conditions for the drops to grow by colliding and merging so the drop size distribution varies based on the location or rainfall types. The rainfall phases is mainly rain and as the diameter of the raindrop increase the fall velocity increase and oblateness decrease. The equation proposed based on the 2DVD tends to underestimated both fall velocity and oblateness compared with observation. Since these varies based on the rainfall characteristics of the observation location, standard equation for fall velocity and oblateness fit for Gimhae area can be developed by continuous observation and data collection hereafter.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.475-478
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• 2003

This study was conducted to compare the design rainfall derived by the at-site and regional frequency analysis based on the regionalization of the precipitation. The regional and at-site design rainfalls were calculated by Log-Pearson type III distribution using Indirect Methods of Moments(WRC). The regional and at-site analysis for the design rainfall were tested by Monte Carlo simulation. Relative root-mean-square error(RRMSE), Relative bias(RBIAS) and Relative reduction(RR) in RRMSE were computed and compared between design rainfalls resulted from observed and simulated data using the regional and at-site analysis. It was shown that the regional analysis procedure can substantially reduce the RRMSE, RBIAS in comparison with those of at-site analysis. Consequently, optimal design rainfalls following the regions and consecutive durations were derived by the regional frequency analysis.

• Current Research on Agriculture and Life Sciences
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• 제16권
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• pp.37-44
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• 1998

낙동강 지류중 하나인 위천유역 및 동성유역권의 수공구조물 설계시 설계홍수량 결정을 위한 기본자료를 제공하고자 시간분포의 유형과 기저유량의 변화에 따른 가능최대홍수량의 양상을 분석하였다. 먼저 수문기상학적인 방법으로 PMP를 추정하고, Blocking방법의 central, advanced 그리고 delayed type를 각각 이용하여 시간 분포시킨 호우를 Clark방법을 이용하여 PMF를 산정한 결과 다음과 같은 결론을 얻었다. 1. PMP시간분포형에 따라서 첨두 PMF는 기저유량에 따라 advanced일 때 3145.3~3348.3cms, central일 때 3774.6~3977.7cms, delayed일 때 3814.6~4017.3cms로 나타났다. 여기서 강우의 시간분포가 advanced type이고 기저유량이 Minimum일 때 central과 delayed에 비하여 첨두PMF가 670cms정도 작게 나타남을 알수 있었다. 따라서 최대 첨두PMF와 최소 첨두PMF는 각각 delayed와 advanced일 때의 4017.3cms와 3145.3cms이며, 결과에 의한 평균 PMF는 3653.6cms로서 이 결과가 위천유역의 설계홍수량으로 타당하다고 사료된다. 2. 평균PMF와 가지야마에 의한 결과치와는 가지야마 값보다 1.7배 큰값으로 나타났고 이는 1,000년에서 10,000년 빈도사이의 홍수량으로 추정된다.

• 경영과학
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• 제32권4호
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• pp.97-108
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• 2015

This study proposes a mathematical model to estimate the economic value of weather forecast service, among which the precipitation forecast service is focused. The value is calculated in terms of users' satisfaction or dissatisfaction resulted from the users' decisions made by using the precipitation probabilistic forecasts and thresholds. The satisfaction values can be quantified by the traditional value score model, which shows the scaled utility values relative to the perfect forecast information. This paper extends the value score concept to a collective value score model which is defined as a weighted sum of users' satisfaction based on threshold distribution in a group of the users. The proposed collective value score model is applied to the picnic scenario by using four hypothetical sets of probabilistic forecasts, i.e., under-confident, over-confident, under-forecast and over-forecast. The application results show that under-confident type of forecasts outperforms the others as a measure of the maximum collective value regardless of users' dissatisfaction patterns caused by two types of forecast errors, e.g., miss and false alarm.

• 한국지역지리학회지
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• 제6권3호
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• pp.139-152
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• 2000

본 연구는 남한에서의 25년간의 여름 강수량으로서 Cluster 분석을 행하여 강수의 지역 특성을 밝혔다. 여름의 강수 현상에서 다우 지역은 남해안 경기 북부 영동 지방에 출현하고, 6월의 강수량은 장마전선과 저기압의 영향에 대부분 의존하고, 7월의 것은 장마전선이 주도하고, 8월에는 태풍이 강하게 작용하고, 9월에는 태풍 장마전선 저기압의 영향에 의한다. 월강수량의 증감 경향은 매월 지역적으로 반씩 출현하며, 특히 다우 지역에서 심하다. 증가 경향은 경기 북부와 영동 지방에서 우세하고, 감소 추세는 남해안 지방과 제주도에서 탁월하다. 월강수량의 변동은 다우 지역에서 크고 소우 지역에서 작고, 그리고 9월에 가장 크고 7월에 가장 작다.

• 분석과학
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• 제11권4호
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• pp.260-265
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• 1998

$Ba^{2+}$와 $Ti^{4+}$이온의 산성용액에서 dimethyl oxalate의 열분해에 의해서 구형이고 ${\mu}m$크기의 barium titanyl oxalate입자를 합성하였다. 침전은 몇 가지 음이온이 공존이온으로 존재하는데서 수행하였다. 입자의 평균크기가 $0.2{\sim}3{\mu}m$이고 독특한 입자분포를 가진 구형의 입자가 지지 음이온의 종류, 옥살산 음이온의 생성속도, 그리고 숙성시간에 따라서 형성되었다. 숙성시간이 120 min에서 용기 밑바닥에 가라앉은 barium titanyl oxalate 입자는 지지 음이온의 종류에 따라 약 $1.5{\sim}3{\mu}m$의 단일 임계크기까지 성장하였다. 고품위의 barium titanyl oxalate를 제조하기 위해 염산이온을 지지음이온으로 선택하고 반응온도를 높혀주어야함을 이로부터 만든 barium titanate의 XRD 스펙트라 및 화학분석 데이터의 검토로 알 수 있었다.

• 물과 미래
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• 제10권1호
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• pp.53-70
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• 1977

The analysis performed here is aimed to increase the familiarity of hydrologic process especially for the small basins which are densely gaged. Kyung An and Mu Shim river basins are selected as a representative basin according to the criteria which UNESCO has established back in 1964 and being operated under the auspice of Ministry of Construction. The data exerted from these basins is utilized for the determination of characteristics of procipitation and runoff phenomena for the small basin, which is considered as a typical Korean samall watershed. The study found that the areal distribution of preciptation did not show any significant deviation from the point rainfall. Since the area studied is less than 20 km#, the pointrainfall may be safely utilized as a representative value for the area. Also the effect of elevation on the precipitation has a minor significance in the small area where the elevation difference is less than 200m. The methodology developed by Soil Conservation Service for determination of runoff value from precipitation is applied to find the suitability of the method to Korean river basin. The soil cover complex number or runoff curve number was determined by comsidering the type of soil, soil cover, land use and other factors such as antecedent moisture content. The average values of CN for Kyung An and Mushim river basins were found to be 63.9 and 63.1 respectively under AMC II, however, values obtained from soil cover complex were less than those from total precipitation and effective precipitation about 10-30%. It may be worth to note that an attention has to be paid in application of SCS method to Korean river basin by adjusting 10-30% increase to the value obtained from soil cover complex. Finally, the design flood hydrograph was consturcted by employing unit hydrograph technique to the dimensionless mass curve. Also a stepwise multiple regression was performed to find the relationship between runoff and API, evapotranspiration rate, 5 days antecedentprecipitation and daily temperature.

• KIEAE Journal
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• 제15권5호
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• pp.5-12
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• 2015

Purpose: Retention and infiltration of small and frequently-occurring rainfall by LID facilities account for a large proportion of the annual precipitation volume. Based on 4 standard facilities such as Porous Pavement, Infiltration Trench, Cylindrical Infiltration Well, Rectangular Infiltration Well by Seoul Metropolitan Handbook of the Prior Consultation for LID. The total retention volume of each facility was calculated according to the type and size. The Purpose of this study is to find out the quantitative relationship between Percentile Rainfall Event and Design Volume of Infiltration Facilities. Methode: For the estimation of Percentile Rainfall Event, Daily Precipitation of Seoul from 2005 to 2014 was sorted ascending and the distribution of percentile was estimated by PERCENTILE spreadsheet function. The managed Rainfall Depth and Percentile of each facility was calculated at the several sizes. In response to the rainwater charge volume of 5.5mm/hr by the Category "Private large site", the 3 types of facilities were planned for example. The calculated Rainfall Depth and Percentile were 54.4mm and 90% by the use of developed Calculation-Module based on the Spreadsheet program. Result: With this Module the existing Designed Infiltration volume which was introduced from Japan was simply converted to the Percentile-Rainfall-Event used in USA.

• 대기
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• 제20권1호
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• pp.37-47
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• 2010

The methods measuring the precipitation drop size distribution(hereafter referred to as DSD) at Cloud Physics Observation System (CPOS) in Daegwallyeong are to use PARSIVEL (PARticle SIze and VELocity) disdrometer (hereafter referred to as PARSIVEL) and Micro Rain Radar (hereafter referred to as MRR). First of all, PARSIVEL and MRR give good correlation coefficients between their rain rates and those of rain gage: $R^2=0.93$ and 0.91, respectively. For the DSD, the rain rates are classified in 3 categories (Category 1: rr (Rain Rate) ${\leq}0.5\;mm\;h^{-1}$, Category 2: $0.5\;mm\;h^-1$ < rr < $4.0\;mm\;h^{-1}$, Category 3: rr ${\geq}4\;mm\;h^{-1}$). The shapes of PARSIVEL and MRR DSD are relatively most similar in category 2. In addition, we retrieve the vertical rain rate and liquid water content from MRR under melting layer, calculated by Cha et al's method, in Daegwallyeong ($37^{\circ}41{\prime}N$, $128^{\circ}45^{\prime}E$, 843 m ASL, mountain area) and Haenam ($34^{\circ}33^{\prime}N$, $126^{\circ}34^{\prime}E$, 4.6 m ASL, coast area). The vertical variations of rain rate and liquid water content in Daegwallyeong are smaller than those in Haenam. We think that this different vertical rain rate characteristic for both sites is due to the vertical different cloud type (convective and stratiform cloud seem dominant at Haenam and Daegwallyeong, respectively). This suggests that the statistical precipitation DSD model, for the application of weather radar and numerical simulation of precipitation processes, be considered differently for the region, which will be performed in near future.

• 한국환경과학회지
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• 제28권12호
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• pp.1157-1169
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• 2019

We used numerical models to reliably analyze the groundwater flow and hydraulic conductivity on Jeju Island. To increase reliability, improvements were made to model application factors such as hydraulic watershed classification, groundwater recharge calculation by precipitation, hydraulic conduction calculation using the pilot point method, and expansion of the observed groundwater level. Analysis of groundwater flow showed that the model-calculated water level was similar to the observed value. However, the Seogwi and West Jeju watersheds showed large differences in groundwater level. These areas need to be analyzed by segmenting the distribution of the hydraulic conductivity. Analyzing the groundwater flow in a sub watershed showed that groundwater flow was similar to values from equipotential lines; therefore, the reliability of the analysis results could be improved. Estimation of hydraulic conductivity distribution according to the results of the groundwater flow simulation for all areas of Jeju Island showed hydraulic conductivity > 100 m/d in the coastal area and 1 - 45 m/d in the upstream area. Notably, hydraulic conductivity was 500 m/d or above in the lowlands of the eastern area, and it was relatively high in some northern and southern areas. Such characteristics were found to be related to distribution of the equipotential lines and type of groundwater occurrence.