Moonjin Lee

Development of KML conversion technology of ENCs

IMO adopt the revision of SOLAS convention on requirement systems for ECDIS and considered an ECDIS as the major system for E-Navigation strategy on marine transportation safety and environment protection. ENC(Electronic Navigational Chart) as the base map of ECDIS is considered as a principal information infrastructure that is essential for navigation tasks. Because ENCs are not easy to utilize for being encoded according to ISO/IEC 8211 file format, used for navigational purpose mainly, it`s required to utilize in parts of Marine GIS and various marine application. In this paper, we developed KML conversion technology for ENC application. In details, we analyzed data model and encoding method of ENC, schema structure and data file of KML. Based on this results, we developed the program of KML conversion of ENCs.

Observation of Wind Direction Change on the Sea Surface Temperature Front Using High-Resolution Full Polarimetric SAR Data

In this study, we derive high-resolution wind speeds and directions from full-polarization synthetic aperture radar (SAR) data. Previous wind retrieval result from conventional single-polarization SAR data has a limitation to resolve small-scale structures in the surface wind because external wind direction data with coarser spatial resolution than those of SARs have been commonly used as an input. Using fully polarimetric SAR data, however, both wind speed and direction can be derived with high resolution from the image itself without any ancillary data. We derive wind field off the southern coast of Korea from the Radarsat-2 quad-polarization data and investigate the spatial variation. The retrieved wind field from the Radarsat-2 image presents a detailed structure including small-scale variations which is unobtainable from conventional wind observations. Comparison of the derived wind directions with in-situ buoy wind measurements shows a small difference of 8° which is regarded as sufficient to analyze small-scale wind vector changes. The retrieved wind field off the southern coast of Korea demonstrates the distinct patterns of direction changes. While blowing over the sea surface temperature (SST) frontal zone, the veering angles of wind vectors decrease and then are restored. The analysis of SAR-derived wind vectors with coinciding temperature distributions confirms that the variation in SAR-derived wind vectors on the SST fronts is mainly induced by the stability effect. This study also addresses the important role of precise wind direction retrieval on the accuracy of retrieved wind speed.

The extraction of ocean wind, wave, and current parameters using SAR imagery

Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette. The Doppler shift measurement of SAR image yields surface speed of the ocean current along the radar looking direction at imagette resolution. In this paper we report the development of a SAR Ocean Processor (SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images along the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of space-borne SAR based oceanographic research.

Study on the Extraction of Ocean Wind, Wave and Current using SAR

최근 인공위성 SAR를 이용한 기술은 해풍, 파랑, 해류 등과 같은 해양에서 발생되는 다양한 현상을 관측하고 연구하는데 필수적인 기술로 대두되고 있다. CMOD4, CMOD-IFR2 모델은 해상풍의 크기를 구할 수 있으며, wave-SAR 변환 기법과 inter-look cross-spectra 기법은 파랑의 크기, 방향과 같은 물리적 값을 추출할 수 있다. 또한 Doppler shift 기법을 적용하여 해류속도를 구할 수 있다. 본 연구에서는 위의 기법들을 종합적으로 적용하여 SOP(SAR Ocean Processor) 프로세서를 개발하였다. 이 프로세서를 한반도 연안 지역에 적용하여 RADARSAT-1 영상자료로부터 해풍, 파랑, 해류의 물리적 정보를 추출하였으며, 이를 현장 관련 자료와 비교하여 신뢰할만한 결과를 얻을 수 있었다. 【Recently satellite SAR techniques have become essential observation tools for various ocean phenomena such as wind, wave, and current. The CMOD4 and CMOD-IFR2 models are used to calculate the magnitude of wind at SAR resolution with no directional information. Combination of the wave-SAR spectrum analysis and the inter-look cross-spectra techniques provides amplitude and direction of the ocean wave over a square-km sized imagette, The Doppler shift measurement of SAR image yields surface speed of the ocean current along the radar looking direction, again at imagette resolution. In this paper we report the development of a SAR Ocean processor(SOP) incorporating all of these techniques. We have applied the SOP to several RADARSAT-1 images of the coast of Korean peninsula and compared the results with oceanographic data, which showed reliability of spaceborne SAR-based oceanographic research.】

Modulation of Tidal Channel Signatures on SAR Images Over Gyeonggi Bay in Relation to Environmental Factors

In this study, variations of radar backscatter features of the tidal channel in Gyeonggi Bay in the Eastern Yellow Sea were investigated using spaceborne synthetic aperture radar (SAR) images. Consistent quasi-linear bright features appeared on the SAR images. Examining the detailed local bathymetry chart, we found that the features were co-located with the major axis of the tidal channel in the region. It was also shown that modulation of the radar backscatter features changed according to the environmental conditions at the time of imaging. For the statistical analysis, the bathymetric features over the tidal channel were extracted by an objective method. In terms of shape, the extracted features had higher variability in width than in length. The analysis of the variation in intensity with the coinciding bathymetric distribution confirmed that the quasi-linear bright features on the SAR images are fundamentally imprinted due to the surface current convergence and divergence caused by the bathymetry-induced tidal current variation. Furthermore, the contribution of environmental factors to the intensity modulation was quantitatively analyzed. A comparison of the variation in normalized radar cross section (NRCS) with tidal current showed a positive correlation only with the perpendicular component of tidal current (r= 0.47). This implies that the modulation in intensity of the tidal channel signatures is mainly affected by the interaction with cross-current flow. On the other hand, the modulation of the NRCS over the tidal channel tended to be degraded as wind speed increased (r= −0.65). Considering the environmental circumstances in the study area, it can be inferred that the imaging capability of SAR for the detection of tidal channel signatures mainly relies on wind speed.

Multi-Spectral Ship Detection using Optical, Hyperspectral, and Microwave SAR Remote Sensing for Sustainability of the Coastal Region

As human activities of the countries in the East Asia have been remarkably expanding over recent decades, various problems in relation to ships, such as oil spill and many other coastal marine pollution, are continuously occurring in the coastal region. In order to conserve marine resources and prepare for possible ship accidents in advance, the need for efficient ship management is increasing over time. Multi-satellite, multi-sensor, multi-wavelength or multifrequency observations make it possible to monitor a variety of vessels in the coastal region. This study presents the results of ship detection methodology applied to multi-spectral satellite images in the seas around Korean Peninsula based on optical, hyperspectral, and microwave remote sensing. To detect ships from hyperspectral images with a few hundreds of spectral channels, spectral matching algorithms are used to investigate similarity between the spectra and in-situ measurements. In the case of SAR (Synthetic Aperture Radar) images, the Constant False Alarm Rate (CFAR) algorithm is used to discriminate the vessels from backscattering coefficients of Sentinel-1 SAR and ALOS-2 PALSAR2 images. The present ship detection methods can be extensively utilized for optical, hyperspectral, and SAR images for comprehensive coastal management purposes toward perpetual sustainability in the future.

Detection and dispersion of oil spills from satellite optical images in a coastal bay

In this study, we accomplished to detect oil spill from DubaiSat-2 and Landsat OLI data using VIS/NIR channels with high spatial resolution and we classified oil spill in two types, such as thick oil and film-like oil. It is hard to recognize film-like oil even at the field and more complex to discriminate film-like oil than thick oil from the satellite data because it shows similar appearance with sea water color and their widespread distributions. In this respect, it is significant that we has developed the algorithm for film-like oil. And also we figured out the effects of tidal current and wind driven current to the movement of oil spill by particle tracking.

Application of Real Time Currents Prediction in Ship Speed Correction of Sea Trial Test

요 약 : 실시간 해수유동 정보를 중심으로 신조선 선박의 실선시운전에서 활용될 수 있는 정보 제공 시스템을 개발하였다. 본 시스템에서 는 실선시운전 지원 정보로서 특정시간 해수유동의 공간분포를 예측하여 제공하며, 특정지점 해수유동의 시계열 변동을 예측하여 제공한다. 또한 본 시스템은 실선시운전에 있어 시험선박 운항경로에서의 해수유동 정보 및 선속 손실정보를 제공하기 위하여 GPS와 연결할 수 있는 기능을 가지고 있으며, 이러한 기능을 이용하여 실선시운전시 자동으로 운항경로상의 해수유동 실시간 정보 및 해수유동에 의한 선속손실을 계산하여 제공한다. 실선시운전 중의 정보 제공 이외에, 본 시스템에서는 특정한 시험시간과 시험경로에 대해 선속손실을 예측하여 제공함으 로써 최적의 시험시간 및 시험경로를 계획할 수 있도록 지원하는 기능도 가지고 있다. 본 연구에서 개발된 실선시운전을 위한 실시간 해수유 동 예측시스템은 효율적인 시험계획과 정확한 해역특성 파악을 지원할 뿐 아니라, 실선에 탑재되어 시험 중에 요구되는 다양한 정보를 제공 한다.

Oil Spill Response System using Server-client GIS

It is necessary to develop the one stop system in order to protect our marine environment rapidly from oil spill accident. The purpose of this study is to develop real time database for oil spill prediction modeling and implement real time prediction modelling with ESI and server-client GIS based user interface. The existing oil spill prediction model cannot provide one stop information system for public and government who should protect sea from oil spill accident. The development of multi user based information system permits integrated handling of real time meteorological data from external ftp. A server-client GIS based model is integrated on the basis of real time database and ESI map to provide the result of the oil spill prediction model. End users can access through the client interface and request analysis such as oil spill prediction and GIS functions on the network as their own purpose.

A Study on improvement method of sounding density of ENCs

ENCs are encoded using a numerical charts developed for publishing paper charts and serviced in forms of grid styles. For this reason, the density of ENCs` sounding information is not consistent and that requires improved methods. In this study, K-Means, ISODATA clustering algorithm as classification methods for satellite image was reviewed and adopted to this case study. The designed algorithm includes loading module for ENC data, improvement algorithm of sounding information, writing module of ENC data. According to the results of algorithm, we could confirm the improved result.