• Atmosphere
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• v.21 no.3
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• pp.243-256
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• 2011

This paper presents the development of new algorithm for identifying and tracking the convective cells in three dimensional reflectivity fields in Cartesian coordinates. First, the radar volume data in spherical coordinate system has been converted into Cartesian coordinate system by the bilinear interpolation. The three-dimensional convective cell has then been identified as a group of spatially consecutive grid points using reflectivity and volume thresholds. The tracking algorithm utilizes a fuzzy logic with four membership functions and their weights. The four fuzzy parameters of speed, area change ratio, reflectivity change ratio, and axis transformation ratio have been newly defined. In order to make their membership functions, the normalized frequency distributions are calculated using the pairs of manually matched cells in the consecutive radar reflectivity fields. The algorithms have been verified for two convective events in summer season. Results show that the algorithms have properly identified storm cells and tracked the same cells successively. The developed algorithms may provide useful short-term forecasting or nowcasting capability of convective storm cells and provide the statistical characteristics of severe weather.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.68-81
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• 2014

This study aims to apply and evaluate the automatic DAD analysis method, which is able to establish the depth-area relationship more efficiently and accurately for point-to-areal rainfall conversion. First, the proposed automatic DAD analysis method tracks the expansion route of area from the storm center, and it is divided into Box-tracking, Point-tracking, Advanced point-tracking according to tracking method. After applying the proposed methods to 10 events occurred in Yongdam-watershed area, we confirmed that the Advanced point-tracking method makes it possible to estimate the maximum average areal rainfal(MAAR) more accurately with consideration of the storm movement and the multi-centered storm. In addition, Advanced point-tracking could reduce the errors of the estimated MAAR induced by increasing the area because it can estimate MAAR for each storm center and compare them at the same time. Finally, the DAD curve for the study area could be derived based on the DAD analysis of the selected 10 events.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.202-202
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• 2020

산지 및 도시에서 발생하는 돌발홍수가 대상인 예경보는 홍수 도달시간이 짧고, 수위가 급격하게 상승하는 특성 때문에 1시간 선행시간 확보를 목표로 한다(MOLIT, 2016). 그러나 현재 돌발홍수 예경보 process에 소요되는 시간은 그 이상으로 확인되고 있다. 또한, 돌발홍수 예경보시스템으로부터 출력된 예측 결과를 사람이 직접 확인해야 한다는 단점도 있다. 본 연구에서는 돌발홍수 예경보 선행시간 1시간 확보를 목표로 backward-forward tracking 기법 기반 예측강우 편의보정기법을 제안하고자 한다. 이 기법은 현재 시점보다 이전에 보정계수를 결정함으로써 돌발홍수 예경보 소요시간을 크게 줄여 돌발홍수 대피시간을 확보할 수 있게 한다. 또한, 보정계수의 결정과 적용이 연속적으로 이루어짐에 따라 10분 간격으로 생성되는 MAPLE의 지속적인 편의보정이 가능하다. 예측강우에 대한 보정계수는 현재보다 10분 이전에 결정한다. 즉, 10분 이전 시점에 생성된 10분, 70분 선행 예측강우에 backward tracking을 적용하여 현재 시점의 호우 위치인 target window를 찾는다. 그리고 target window에서 보정계수를 결정한다. 결정된 보정계수는 돌발홍수발령 대상지역인 correction window의 현재 생성된 60분 선행 예측강우에 적용한다. 이 과정에서 과거 시점 10분 선행 예측강우와 현재 시점에 생성된 60분 선행 예측강우와의 forward tracking이 수행된다. Storm tracking 기법으로는 두 예측강우의 호우패턴에 대한 유사성을 정량화한 패턴상관계수를 이용하였다. 대상 호우사상으로는 2016년에 발생한 주요 호우사상을 선정하였다. 본 연구에서 제안하는 기법을 적용하고, 편의보정 결과를 기존 편의보정기법 적용 결과와 비교하였다.

• Water Engineering Research
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• v.3 no.2
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• pp.113-122
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• 2002

Accurate quantitative forecasting of rainfall for basins with a short response time is essential to predict flash floods. In this study, a Quantitative Flood Forecasting (QFF) model was developed by incorporating the evolving structure and frequency of intense weather systems and by using neural network approach. Besides using radiosonde and rainfall data, the model also used the satellite-derived characteristics of storm systems such as tropical cyclones, mesoscale convective complex systems and convective cloud clusters as input. The convective classification and tracking system (CCATS) was used to identify and quantify storm properties such as lifetime, area, eccentricity, and track. As in standard expert prediction systems, the fundamental structure of the neural network model was learned from the hydroclimatology of the relationships between weather system, rainfall production and streamflow response in the study area. All these processes stretched leadtime up to 18 hours. The QFF model will be applied to the mid-Atlantic region of United States in a forthcoming paper.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.157-164
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• 2015

The present study is to identify discharge characteristic from the mouth of floating debris in the Nakdong River through real time tracking of moving route and by analyzing hydrometeorologic environmental. To identify the path and route of outflow through the mouth of the river of floating debris, small-sized buoy equipped with satellite location transmitters was used. Moreover, to identify hydrometeorologic environmental, flux of the river, change of discharge of the River-Mouth Weir and wind direction of the mouth of the river area were analyzed. From now on, the present study is expected to be utilized as basic data to identify damage and flowing into nearby ocean of the floating debris of Nakdong River in time of severe rain storm.

• Environmental Engineering Research
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• v.17 no.3
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• pp.167-174
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• 2012

In situ particle size spectra are obtained from two sequent cruises in order to evaluate the physical consequences of suspended particulate matters caused by episodic storm runoff from the Santa Ana River watershed, an urbanized coastal watershed. Suspended particles from various sources including surface runoff, near-bed resuspension, and phytoplankton are identified in empirical orthogonal function (EOF) analysis and an entropy-based parameterization (Shannon entropy). The first EOF mode is associated with high turbidity and fine particles as indicated by the elevated beam attenuation near the Santa Ana River and Newport Bay outlets, and the second EOF mode explains the suspended sediment dispersal and particle coarsening at the near-surface plume. Chlorophyll particles are also distinguished by negative magnitudes of the first EOF mode, which is supported by the relationship between fluorescence and beam attenuation. The integrated observation between the first EOF mode and the Shannon entropy index accentuates the characteristics of two different structures and/or sources of sediment particles; the near-surface plumes are originated from runoff water outflow, while the near-bottom particles are resuspended due to increased wave heights or mobilizing bottom turbidity currents. In a coastal pollution context, these methods may offer useful means of characterizing particle-associated pollutants for purposes of source tracking and environmental interpretation.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.191-211
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• 2017

Assessment of a storm is accomplished by the duration and storm area rather than a simple analysis given by the ground rain gauge stations. One of the best method for assessing storm is Depth-Area-Duration(DAD) of rainfall analysis. but existing DAD analysis method is likely to possible errors. Therefore, DAD analysis and its applicability were examined using a grid-based DAD analysis program that can reduce the possibility of errors in this study. Three spatial distribution techniques were used to analyze the applicability. Then, DAD analysis was performed using the converted grid-based rainfall data. As a result, it was possible to estimate the MAAR values by area for each duration, and showed high applicability in the rainfall data using ordinary kriging technique.

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.43-50
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• 2020

We have developed an algorithm for tracking coronal mass ejection (CME) propagation that allows us to estimate CME speed and its arrival time at Earth. The algorithm may be used either to forecast the CME's arrival on the day of the forecast or to update the CME tracking information for the next day's forecast. In our case study, we successfully tracked CME propagation using the algorithm based on g-values of interplanetary scintillation (IPS) observation provided by the Institute for Space-Earth Environmental Research (ISEE). We were able to forecast the arrival time (Δt = 0.30 h) and speed (Δv = 20 km/s) of a CME event on October 2, 2000. From the CME-interplanetary CME (ICME) pairs provided by Cane & Richardson (2003), we selected 50 events to evaluate the algorithm's forecast capability. Average errors for arrival time and speed were 11.14 h and 310 km/s, respectively. Results demonstrated that g-values obtained continuously from any single station observation were able to be used as a proxy for CME speed. Therefore, our algorithm may give stable daily forecasts of CME position and speed during propagation in the region of 0.2-1 AU using the IPS g-values, even if IPS velocity observations are insufficient. We expect that this algorithm may be widely accepted for use in space weather forecasting in the near future.

• Journal of Ocean Engineering and Technology
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• v.37 no.4
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• pp.158-163
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• 2023

Objects adrift can cause considerable damage to coastal infrastructure and property during tsunami and storm surge events. Despite the potential for harm, the drifting behavior of these objects remains poorly understood, thereby hindering effective prediction and mitigation of collision damage. To address this gap, this study employed a motion analysis program to track a drifting container's location using images from an existing laboratory experiment. The container's trajectory and velocity were calculated based on the positions of five markers strategically placed at its four corners and center. Our findings indicate that the container's maximum drift velocity and distance are directly influenced by the scale of the solitary wave and inversely related to the container's weight. Specifically, heavier containers are less likely to be displaced by solitary waves, while larger waves can damage coastal structures more. This study offers new insights into container drift behavior induced by solitary waves, with implications for enhancing coastal infrastructure design and devising mitigation strategies to minimize the risk of collision damage.

• Journal of Astronomy and Space Sciences
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• v.29 no.4
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• pp.343-349
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• 2012

The solar proton telescope (SPT) is considered as one of the scientific instruments to be installed in instruments for the study of space storm (ISSS) which is determined for next generation small satellite-1 (NEXTSat-1). The SPT is the instrument that acquires the information on energetic particles, especially the energy and flux of proton, according to the solar activity in the space radiation environment. We performed the simulation to determine the specification of the SPT using geometry and tracking 4 (GEANT4). The simulation was performed in the range of 0.6-1,000 MeV considering that the proton, which is to be detected, corresponds to the high energy region according to the solar activity in the space radiation environment. By using aluminum as a blocking material and adjusting the energy detection range, we determined total 7 channels (0.6~5, 5~10, 10~20, 20~35, 35~52, 52~72, and >72 MeV) for the energy range of SPT. In the SPT, the proton energy was distinguished using linear energy transfer to compare with or discriminate from relativistic electron for the channels P1-P3 which are the range of less than 20 MeV, and above those channels, the energy was determined on the basis of whether silicon semiconductor detector (SSD) signal can pass or not. To determine the optimal channel, we performed the conceptual design of payload which uses the SSD. The designed SPT will improve the understanding on the capture and decline of solar energetic particles at the radiation belt by measuring the energetic proton.