• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.522-522
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• 2015

In this study, the effect of threshold applied to the radar rain rate on the comparison of the radar and rain gauge rain rate was theoretically examined. The result derived was also evaluated theoretically, using the Bernoulli random field, and empirically, using Mt. Kwanak weather radar data. The results are summarized as follows. (1) In the application to the Bernoulli random field, it was found that the comparison of the radar and rain gauge rain rate with threshold does not introduce any systematic bias. (2) The same results could also be derived in the application to Mt Kwanak weather radar data. In all cases with several radar bin sizes and thresholds considered, the bias was estimated to be far less than 10% of the mean of the rain gauge rain rate. (3) However, in the comparison with threshold applied to both the radar and rain gauge rain rate, the bias was estimated to be higher than 20%. That is, the systematic bias was introduced. This result indicates that the comparison with threshold applied to both the radar and rain gauge rain rate should not be used.

• Journal of information and communication convergence engineering
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• 제14권3호
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• pp.153-162
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• 2016

Microwave and millimeter waves are considered suitable frequency ranges for diverse applications. The prediction of rain attenuation required the 1-min rainfall rate distribution, particularly for data obtained locally from experimental measurement campaigns over a given location. Rainfall rate data acquired from Korea Meteorological Administration (KMA) for nine major sites are analyzed to investigate the statistical stability of the cumulative distribution of rainfall rate, as obtained from a 10-year measurement. In this study, we use the following rain rate conversion techniques: Segal, Burgueno et al., Chebil and Rahman, exponential, and proposed global coefficient methods. The performance of the proposed technique is tested against that of the existing rain rate conversion techniques. The nine sites considered for the average 1-min rain rate derivation are Gwangju, Daegu, Daejeon, Busan, Seogwipo, Seoul, Ulsan, Incheon, and Chuncheon. In this paper, we propose a conversion technique for a suitable estimation of the 1-min rainfall rate distribution.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.34-37
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• 1998

Signal Attenuation in the design of satellite channel is due mostly to rain. In this paper, the rain rate characteristics based on the recent year(1994-1996) data for Changwon-Masan were approximated to Moupfouma distribution, and the parameters of distribution were calculated from a simple conversion method of 1-h rate to 1-min rain rate data. From rain rate characteristics, the rain attenuation was estimated and compared with CCR model, Global model and SAM model.

• 대한원격탐사학회지
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• 제24권1호
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• pp.17-24
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• 2008

Rainfall data from three different types of rain gauge system have been collected for the summertime rain event at Mokpo in the Korean peninsula. The rain gauge system considered in this paper is composed of three tipping-bucket rain gauges with 0.1, 0.2, and 0.5 mm measuring resolutions, the Optical Rain Gauge (ORG), and the PARSIVEL (PARticle SIze and VELocity). The PARSIVEL rainfall rate has been considered as the reference for comparison since it gave good resolution and performance on this event. Comparison with the PARSIVEL rainfall rate gives the results that the error and temporal variation of rainfall rate are simultaneously reduced with increasing the averaging interval of rainfall rate or decreasing the size of tipping bucket. This suggests that the estimated rainfall rate must be optimized, differently for the type of tipping-bucket rain gages, by minimizing the averaging interval of rainfall rate under the condition satisfying the given performance of rainfall rate.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1575-1577
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• 2002

In this research we propose a method far rain rate estimation by using Doppler spectrum's data of wind profiler. The Doppler spectrum is used to calculate the wind velocity and wind direction. But in this research uses the parameters from Doppler spectrum, it calculates the rain rate. The rain rate estimation in this method will be compared to the obtained rain rate from the surface rain gauge. Two equipments are installed in the same area. The correlation coefficient between rain rate measuring method is 0.65.

• 한국지구과학회지
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• 제23권1호
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• pp.59-71
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• 2002

Theoretical models of radiative transfer are developed to simulate the 85 GHz brightness temperature (T85) observed by the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer as a function of rain rate. These simulations are performed separately over regions of the convective and stratiform rain. TRMM Precipitation Radar (PR) observations are utilized to construct vertical profiles of hydrometeors in the regions. For a given rain rate, the extinction in 85 GHz due to hydrometeors above the freezing level is found to be relatively weak in the convective regions compared to that in the stratiform. The hydrometeor profile above the freezing level responsible for the weak extinction in convective regions is inferred from theoretical considerations to contain two layers: 1) a mixed (or mixed-phase) layer of 2 km thickness with mixed-phase particles, liquid drops and graupel above the freezing level, and 2) a layer of graupel extending from the top of the mixed layer to the cloud top. Strong extinction in the stratiform regions is inferred to result from slowly-falling, low-density ice aggregates (snow) above the freezing level. These theoretical results are consistent with the T85 measured by TMI, and with the rain rate deduced from PR for the convective and stratiform rain regions. On the basis of this study, the accuracy of the rain rate sensed by TMI is inferred to depend critically on the specification of the convective or stratiform nature of the rain.

• 한국전자파학회논문지
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• 제23권11호
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• pp.1272-1279
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• 2012

본 논문에서는 기상청의 10년간의 1분 단위 강수량 측정 데이터를 이용하여 국내 환경에 대한 연평균 강우율 분포 및 강우율 분포와 최악월 강우율 분포의 상관 관계 모델을 제시하였다. 본 논문에서 제시한 모델을 기존의 ITU(International Telecommunication Union)-R 권고 모델과 비교한 결과, 시간율 0.01 %에 대해서 국내 연평균 강우율의 전국 평균값은 ITU-R 권고 문서의 강우율에 비하여 약 28 % 높게 나타났다. 또한, 연평균 및 최악월 강우율 분포 간의 상관 관계도 본 논문의 모델과 ITU-R 권고 문서의 모델은 상당히 큰 차이를 보였다. 앞으로 국내 무선 통신 시스템 설계에 필수적인 강우 감쇠의 통계적 특성(시간율 분포) 계산을 위해서는 국내 환경에 적합한 강우율 분포 모델을 사용하여야 할 것으로 판단된다.

• Journal of electromagnetic engineering and science
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• 제8권2호
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• pp.84-89
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• 2008

In a wireless channel above microwave frequency, rain attenuation is very important. In order to predict rain attenuation, 1-min. rain rate distribution is required. This paper discusses appropriate conversion methods to estimate 1-minute rain rate from that of other integration time. Based on the measurement data filed in ITU-R WP3J including ETRI data for 6 consecutive years, distributions of rain rate with 1-, 5-, 10-, 20-, 30-minute integration time were analyzed, both on the global and regional basis, and the parametric relationship between the statistical characteristics of 1-minute and other measurement data were investigated to deduce the conversion methods. It is shown that the global model works good with good accuracy for 5-, 10-, 20-min integration time, and the global model is also applicable globally with good accuracy for 5-, 10-, 20-min integration time. The global conversion model was adopted last year as an ITU-R document for new recommendation. The regional conversion model would also be very useful for locations of similar climatic zone.

• 한국전자파학회논문지
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• 제9권3호
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• pp.410-418
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• 1998

밀리미터파대역의 강우감쇄와 교차편파를 여러 나라의 측정치와 비교하였다. 그리고 국내환경에 적용할 수 있도록 $\tau$분 강우율을 1분 가우율롤 변환할 수 있는 변환모델을 제시하였다. 변환한 국내의 가웅율 데이타를 이요하여, 강우감쇄와 교차편파의 확률분포를 다양한 모델을 이용하여 계산하고, 그 결과를 서로 비교하였다.

• 한국통신학회논문지
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• 제23권7호
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• pp.1755-1763
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• 1998

약 10GHz 이상의 주파수를 사용하는 무선 채널에서 채널의 가용도는 강우감쇄에 심각한 영향을 받는다. 강우감쇄의 영향은 주파수와 지역적 상황에 따라 다르다. 본 논문에서는 국내환경에 적용할 수 있는 밀리미터파대역의 강우감쇄를 추정하였다. 빗방울 크기분포는 지수분포로 가정하였고, 빗방울 크기분포를 변화시켜가며 국내환경과 유사한 여러나라의 측정치를 비교하고 분석하여 국내환경에 적용시킬 수 있는 빗방울 크기분포를 보였다. 또한, r분 강우율을 1분 강우율로 변환할 수 있는 변환모델을 논하고 이를 적용하여 변환한 국내의 강우율데이타를 이용하여 강우감쇄의 확률분포를 계산하였다.