• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.8 s.111
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• pp.767-772
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• 2006

The receiver of this paper is Dual-band monopulse type for prototype of tracking radar. Localization of radar technology is an issue of SamsungThales and go into development. Dual-band radar in comparison with Single-band radar requires higher cost and power consumption but there are many advantages of dealing with jamming, detection range, image signal rejection, cloud-rain influence, clutter, resolution. The receiver is comprised of X-band RF head module, Ka-band RF head module and common IF module. Each signal of X-band and Ka-band is selected by the switch in If module. Phase shifter in IF module of local stage controls the phase of sum, azimuth, elevation channel. In the test result, gain is $40{\pm}3 dB$, isolation of transmitter/receiver is 39 dBc, dynamic range is 110 dB and noise figure of each channel is 4.5dB and 6.9dB.

• Journal of the Korean earth science society
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• v.31 no.5
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• pp.465-474
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• 2010

Real-time rainfall monitoring is of great practical importance over the highly populated Indochina area, which is prone to natural disasters, in particular in association with rainfall. With the goal of d etermining near real-time half-hourlyrain estimates from satellite, the three-layer, artificial neural networks (ANN) approach was used to train the brightness temperatures at 6.7, 11, and $12-{\mu}m$ channels of the Japanese geostationary satellite MTSAT against passive microwavebased rain rates from Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and TRMM Precipitation Radar (PR) data for the June-September 2005 period. The developed model was applied to the MTSAT data for the June-September 2006 period. The results demonstrate that the developed algorithm is comparable to the PERSIANN (Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks) results and can be used for flood monitoring across the Indochina area on a half-hourly time scale.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.378-381
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• 2007

Analyses of Tropical Rainfall Measuring Mission (TRMM) microwave radiometer (TMI) and precipitation radar (PR) data show that the rainfall inhomogeneity, represented by the coefficient of variation, decreases as rain rate increases at the low resolution (the footprint size of TMI 10 GHz channel). The rainfall inhomogeneity, however, is relatively constant for all rain rates at the high resolution (the footprint size of TMI 37 GHz channel). Consequently, radiometric signatures at lower spatial resolutions are characterized by larger dynamic range and smaller variability than those at higher spatial resolution. Based on the observed characteristics, this study develops a low-resolution (${\sim}40{\times}40$ km) rainfall retrieval algorithm utilizing realistic rainfall distributions in the a-priori databases. The purpose of the low-resolution rainfall algorithm is to make more reliable climatological rainfalls from various microwave sensors, including low-resolution radiometers.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.465-465
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• 2015

강우/무강우 정보는 재해의 관점에서는 중요성이 덜하지만 농업, 건설 등의 산업분야나 우리의 일상생활에 큰 영향을 미치는 인자이다. 본 연구에서는 레이더 자료를 이용하여 강우발생을 판단하는데 있어 그 정확성을 살펴보고, 아울러 이를 높이기 위한 방법으로 가강수량의 역할을 평가하였다. 본 연구에서는 관악산 레이더 자료, 관악산 레이더 반경 내 위치한 30개 AWS지점의 강우 자료를 분석하였다. 30개 AWS지점은 관악산 레이더 반경을 전체적으로 포괄할 수 있도록 임의로 선정하였다. 또한, 오산과 백령도 고층기상관측자료를 이용하여 산정한 가강수량을 레이더 강우발생 판단에 적용하여 정확성 개선을 검토하였다. 아울러 본 연구의 결과를 2차원 평면에 나타내어 공간적인 변화를 비교하였다.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.201-203
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• 2004

We present here, some of the studies carried for estimation of rainfall over land and oceanic regions in and around South Korea. We use active and passive microwave measurements from TRMM - TMI and Precipitation Radar (PR) respectively during a typhoon even named - RUSA that took place during 30 Aug. 2002. We have followed due approach by Yao at. all (2002) and examined the performance of their algorithm using two main predictor variable, named as Scattering Index (SI) and Polarization Corrected Brightness Temperature (PCT) while using TMI data. The rainfall rate estimated using PCT and SI shows some under-estimation as compared to the AWS rainfall products from the PR in common area of overlap. A larger database thus would be used in future. To establish a new rain rate algorithm over Korean region based on the present case study.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.413-413
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• 2015

최근 국내외적으로 정도 높은 강우장을 모의하기 위해 레이더 자료와 강우자료를 합성하려는 연구가 수행되고 있다. 이는 정밀하게 강우를 관측할 수 있는 지점 강우의 장점과 강우의 공간분포를 파악할 수 있는 레이더 자료의 장점을 결합하여 고품질의 자료를 생산할 수 있기 때문이다. 기존에는 연속수정법, 조건부 합성기법, 코크리깅, 가우시안 합성기법 등과 같은 자료합성 기법을 이용하여 레이더 자료와 지상강우를 합성한 연구가 수행되었다. 그러나 강우자료의 간헐적인 특징으로 인하여 두 자료를 합성하려는 시도는 간단하지 않은 문제로 나타났다. 이에 본 연구에서는 간헐적 특성의 자료를 고려한 자료합성 기법을 제안하였다. 먼저, 자료를 0이 포함되지 않은 경우와 0이 포함된 경우의 2가지 유형으로 구분하였다. 기존에는 주로 자료에 0에 포함되지 않은 경우에 대한 합성기법이 평가되었지만, 본 연구에서는 0이 포함된 경우에 대한 합성기법에 초점을 맞추었다. 자료합성 기법 중 코크리깅 기법을 이용하여 0이 포함된 레이더 자료와 강우자료를 합성하는 방법을 제안하였고 이를 0이 포함되지 않은 경우를 이용한 합성 결과와 비교하였다. 아울러 제안된 합성기법을 한강 유역의 자료에 적용하여 그 결과를 비교 및 평가 하였다.

• Journal of Korea Water Resources Association
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• v.53 no.6
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• pp.417-425
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• 2020

In order to predict and prevent hydrological disasters such as flood, it is necessary to accurately estimate rainfall. In this paper, an areal average rainfall estimation method using multiple elevation observation data of an electromagnetic wave rain gauge is presented. The small electromagnetic rain gauge system is a very small precipitation radar that operates at K-band with dual-polarization technology for very short distance observation. The areal average rainfall estimation method is based on the assumption that the variation in rainfall over the observation range is small because the observation distance and time are very short. The proposed method has been evaluated by comparing with ground instruments such as tipping-bucket rain gauges and a Parsivel. The evaluation results show that the methodology works fairly well for the rainfall events which are shown here.

• Journal of Korea Water Resources Association
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• v.47 no.2
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• pp.119-133
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• 2014

The study adopted extended Kalman filter technique in an effort to predict Z-R relationship parameter as a stable value in real-time. Toward this end, a parameter estimation model was established based on extended Kalman filter in consideration of non-linearity of Z-R relationship. A state-space model was established based on a study that was conducted by Adamowski and Muir (1989). Two parameters of Z-R relationship were set as state variables of the state-space model. As a result, a stable model where a divergence of Kalman gain and state variables are not generated was established. It is noteworthy that overestimated or underestimated parameters based on a conventional method were filtered and removed. As application of inappropriate parameters might cause physically unrealistic rain rate estimation, it can be more effective in terms of quantitative precipitation estimation. As a result of estimation on radar rainfall based on parameters predicted with the extended Kalman filter, the mean field bias correction factor turned out to be around 1.0 indicating that there was a minor difference from the gauge rain rate without the mean field bias correction. In addition, it turned out that it was possible to conduct more accurate estimation on radar rainfall compared to the conventional method.

• Journal of Korea Water Resources Association
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• v.42 no.12
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• pp.1039-1052
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• 2009

Radar measurement with high temporal and spatial resolutions can be a valuable source of data, especially in the areas where rain gauge installment is not practical. However, this kind of data brings with it many errors. The objective of this paper is to propose a method to evaluate statistically the quantitative and qualitative accuracy at different radar ranges, temporal intervals and raingage densities and use a bias adjustment technique to improve the quality of radar rainfall for the purpose of hydrological application. The method is tested with the data of 2 storm events collected at Jindo (S band) and Kwanak (C band) radar stations. The obtained results show that the accuracy of radar rainfall estimation increases when time interval rises. Radar data at the shorter range seems to be more accurate than the further one, especially for C-band radar. Using the Monte Carlo simulation experiment, we find out that the sampling error of the bias between radar and gauge rainfall reduces nonlinearly with increasing raingage density. The accuracy can be improved considerably if the real-time bias adjustment is applied, making adjusted radar rainfall to be adequately good to apply for hydrological application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1292-1299
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• 2014

Weather radar systems can provide weather information of the ground, sea, and air in extensive spatial coverage in near real time. However, it becomes problematic when ground clutter signal exists around precipitation because strong signals of ground can cause a false precipitation report. A large percentage of land coverage of Korea consists of mountainous regions where ground clutter needs to be mitigated for more accurate prediction. Thus, it is considered necessary to introduce a new suitable ground clutter removal technique specifically adequate for Korea. In this paper, the C-Map(Clutter Map) method using raw radar signals is proposed for removing ground clutter using a terrain-adaptive clutter map. A clutter map is generated using raw radar signals(I/Q) of clear days, then it is subtracted from received radar signals in frequency domain. The proposed method is applied to the radar data acquired from Sobaeksan rain radar and the result shows that the clutter rejection ratio is about 91.17 %.