• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.195-196
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• 2006

Recently, there are increasing need to make a synthetic assessment about oceanic data which is collected over the various scientific field, in addition to just gathering oceanic data. In this study, we made a basic map using satellite image, aerial photo, multi-beam data, geological stratum data etc. And as well we are producing comprehensive SVT(Scientific Visualization Toolkit) which can visualize various kinds of oceanic data. These oceanic data include both survey data such as tidal height, tide, current, wave, water temperature, salinity, oceanic weather data and numeric modelling results such as ocean hydrodynamic model, wave model, erosion/sediment model, thermal discharged coastal water model, ocean water quality model. In this process, we introduce GIS(Geographic Information System) concepts to reflect time and spatial characteristics of oceanic data.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.26-28
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• 2008

Soil moisture plays an important role in the land-atmosphere energy balance because it governs the partitioning of energy through latent heat fluxes or evapotranspiration. From the numerous studies, it is evident that the L-band radiometer is a useful and effective tool to measure soil moisture. The objective of the study is to develop and to verify the soil moisture retrieval algorithms for the L-band radiometer system. Through the radiometer-observed brightness temperature, surface emissivity and reflectivity can be derived, and, hence, soil moisture. We collect field and L-band airborne radiometer data from washita92, SGP97 and SGP99 experiments to assist the development of the retrieval algorithms. Upon launching the satellite L-band radiometer such as ESA-sponsored SMOS (Soil Moisture and Ocean Salinity) mission, the developed algorithms may be used to study and monitor globe soil moisture change.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.705-712
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• 2009

The state changes of ocean covered over 70% of earth surface are one of the greatest factor of weather catastrophe. Recently weather extraordinary events are followed by steep increase of sea water temperature and scientists in various fields are studying and warning the weather changes. In this paper, floating buoy is developed to monitor ocean environments via Orbcomm satellite and a method is proposed to increase measurement accuracy of sea water temperature with common low price temperature sensor. Experimental results are presented to illustrate the usability and effectiveness of the developed system. A web-based real time monitoring system is built to monitor ocean environmental information such as sea and air temperature, salinity according to the position of buoy through the internet for user convenience.

• 한국해양학회지
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• v.30 no.5
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• pp.512-521
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• 1995

To investigate a short-term (from 2 hours to 24 hours) variability of a mixed layer, oceanographical data (water temperature, salinity, current) and meteorological data (wind, air temperature, solar radiation) were collected at a site in the Korea Strait at the interval of one hour for 48 hours from October 12 to 14, 1993. The average rates of temporal variations of the mixed layer depth (MLD) and temperature of the mixed layer (MLT), which are very weakly correlated with the wind stress and buoyancy flux at the sea surface, are about 5.2 m/hour and 0.2$^{\circ}C$/hour, respectively. The mixed layer is relatively shallow when both MLT and MLS (salinity of the mixed layer) are low, while MLD is relatively deep when they are high. MLT shows a sudden decrease or increase. Analysis of satellite infrared images and XBT data shows that sudden increase of MLT is caused by advection of warm water. These results suggest that the short-term variation of the mixed layer in the Korea Strait in autumn, in which surface current is relatively strong and different water masses exist, is mainly determined by advection rather than air0sea interaction such as wind stress or buoyancy flux.

• Journal of Environmental Science International
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• v.17 no.9
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• pp.949-956
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• 2008

The data of temperature, chlorophyll a, phytoplankton and NOAA/AVHRR satellite data were analyzed about 7 stations around Wando Island area on August 30, 2005. The sea water temperature range was from $15.19^{\circ}C$ to $24.97^{\circ}C$, and there was a cold water mass from the station 1 to 5 around the outside of Chungsando Island, the water temperature was lower at the bottom than surface. The salinity was $32.41{\sim}34.03$, DO was $7.40{\sim}9.14mg/L$, but the concentration of chlorophyll a was 1ug/L higher at the bottom than surface. Total phytoplankton appeared from the whole stations were 47 genus, 80 species and diatoms were dominant. A lot of dinoflagellates Ceratium forca and diatoms Thalassithrix spp. mostly appeared in the cold water mass were turned up from the station 1 to 5. 4 groups of phytoplankton clusters were shown in the surface, and 3 groups of phytoplankton clusters were shown at the bottom according to the water temperature. On the ground of the result analyzed with NOAA/AVHRR satellite data, the SST around Wando Island was $22{\sim}25^{\circ}C$, it was formed by thermohaline front latitudinally

• Ocean Science Journal
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• v.41 no.3
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• pp.181-189
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• 2006

Frontal areas between warm and saline waters of the Kuroshio currents and colder and diluted waters of the East China Sea (ECS) influenced by the Changjiang River were identified from the satellite thermal imagery and hydrological data obtained from the Coastal Ocean Process Experiment (COPEX) cruise during the period between March $1^{st}$ and $10^{th}$, 1997. High chlorophyll concentrations appeared in the fronts of the East China Seas with the highest chlorophyll-a concentration in the southwestern area of Jeju Island (${\sim}2.9\;mg/m^3$) and the eastern area of the Changjiang River Mouth (${\sim}2.8\;mg/m^3$). Vertical structures of temperature, salinity and density were similar, showing the fronts between ECS and Kuroshio waters. The water column was well mixed in the shelf waters and was stratified around the fronts. It is inferred that the optimal condition for light utilization and nutrients induced both from the coastal and deep waters enhances the high phytoplankton productivity in the fronts of the ECS. In addition, the high chlorophyll-a in the fronts seems to have been associated with the water column stability as well.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.187-187
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• 2015

인공위성을 이용한 토양수분의 측정은, 범지구적인 물순환 분석에 있어서, 수문학적인 인자들의 시공간적인 변화를 예측, 분석하는데 있어 가장 효율적인 방법으로 제안되어왔다. 현재 국/내 외 적으로 사용하는 토양수분 위성은 Soil Moisture and Ocean Salinity (SMOS), Advanced SCATerometer (ASCAT)이 많이 사용되고 있으며, 더불어 일본에서 최근에 발사 된 Advanced Microwave Scanning Radiomter 2 (AMSR2) 센서를 통한 토양수분도 데이터도 적극 활용 되고 있다. 각 위성은 토양수분을 산출 하는 알고리즘, 파장대 그리고 위성 통과 시간 등이 각기 다르므로, 이러한 위성의 데이터를 사용하기 위해서는 지점 데이터와의 검증이 필수적으로 필요하게 된다. 이에따라 본 연구에서는 위성 데이터와 Global Land Data Assimilation System (GLDAS)와의 비교를 통해 각 위성데이터의 동아시아 지역에서의 효용성을 평가하였다. 동아시아의 건조한 지역에서는 SMOS가 가장 좋은 토양수분 데이터 결과를 보여주었으며, 다른 많은 지역에서는 ASCAT이 우세한 결과를 보여주었다. 하지만 한반도 지역의 특정 지역에서는 AMSR2의 토양수분 값이 ASCAT을 뛰어넘는 좋은 결과를 보여주는 결과가 도출되었다. 추가적으로, SMOS의 경우 Radio Frequency Interference (RFI)의 영향으로 한반도지역 토양수분을 측정하는 것에는 많은 무리가 있음을 알 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.31-31
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• 2015

토양수분은 일반적으로 시료를 채취하거나 현장에 설치된 다양한 센서를 통해 추정하지만 이는 시간과 비용이 많이 소모되기 ?문에 유역내의 공간적인 토양수분 분포를 추정하는데 상당한 어려움이 따른다. 토양수분뿐만 아니라 공간적인 대기현상, 토양수분, 식생현황 등을 관측하는데 대중적으로 사용되는 것이 위성 관측이며, 기본적으로는 위성에 탑재된 센서가 각 주파수대역에 따라 영상을 생성하면 이를 특정 알고리듬을 적용하여 원하는 값을 도출하게 된다. 토양수분 산정에 사용되는 대표적인 위성영상으로는 SMOS (Soil Moisture and Ocean Salinity), ARMS-E(Advanced Microwave Scanning Radiometer - Earth Observing System), ARMS2 (ARMS ver.2) 영상 등이 있으며, 이러한 위성은 해상도가 약 10 km ~ 40 km로 상당이 낮기 때문에 우리나라와 같이 면적이 좁고 지형이 복잡하며 다양한 토지피복이 밀집되어있는 곳에서는 기존 수문 연구에 응용할 수 있는 토양수분 공간지도 산정을 위해 상세화(Downscaling)과정이 필요하다고 판단된다. 따라서 본 연구에서는 ARMS2 토양수분 영상을 MODIS 영상의 식생지수(NDVI, Normalized Difference Vegetation Index), 알베도 및 온도를 활용하여 공간적으로 상세화된 토양 수분 지도를 작성하였고, 유역 내에서 실제 측정되고 있는 토양수분 관측값을 활용하여 상세화기법의 적용성을 검토하였다.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.251-262
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• 2010

In order to provide quantitative control of the standard products of Geostationary Ocean Color Imager (GOCI), on-board radiometric correction, atmospheric correction, and bio-optical algorithm are obtained continuously by comprehensive and consistent calibration and validation procedures. The calibration/validation for radiometric, atmospheric, and bio-optical data of GOCI uses temperature, salinity, ocean optics, fluorescence, and turbidity data sets from buoy and platform systems, and periodic oceanic environmental data. For calibration and validation of GOCI, we compared radiometric data between in-situ measurement and HyperSAS data installed in the Ieodo ocean research station, and between HyperSAS and SeaWiFS radiance. HyperSAS data were slightly different in in-situ radiance and irradiance, but they did not have spectral shift in absorption bands. Although all radiance bands measured between HyperSAS and SeaWiFS had an average 25% error, the 11% absolute error was relatively lower when atmospheric correction bands were omitted. This error is related to the SeaWiFS standard atmospheric correction process. We have to consider and improve this error rate for calibration and validation of GOCI. A reference target site around Dokdo Island was used for studying calibration and validation of GOCI. In-situ ocean- and bio-optical data were collected during August and October, 2009. Reflectance spectra around Dokdo Island showed optical characteristic of Case-1 Water. Absorption spectra of chlorophyll, suspended matter, and dissolved organic matter also showed their spectral characteristics. MODIS Aqua-derived chlorophyll-a concentration was well correlated with in-situ fluorometer value, which installed in Dokdo buoy. As we strive to solv the problems of radiometric, atmospheric, and bio-optical correction, it is important to be able to progress and improve the future quality of calibration and validation of GOCI.

• Ocean Science Journal
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• v.40 no.1
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• pp.25-44
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• 2005

Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-tenn current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.