• Korean Journal of Remote Sensing
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• v.9 no.1
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• pp.79-93
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• 1993

The relative geostrophic velocity is estimated by using the MCSST(Multi-Channel Sea Surface Temperature) from a NOAA/AVHRR image and applied to the Korea Strait. Remote sensing technique can play a useful role to research for oceanic phenomena because of its synoptic, simultaneous and repetitive viewing. The high resolution data of AVHRR can determine the geostrophic flow more precisely than the hydrographic data on shipboard. As a result of research, the relative geostrophic velocity in the weatern channel of the Korea Strait is the strongest in the trough area and its maximum speed is about 23.8cm/sec in April, 1992. But this results include the error due to neglecting the effect of salinity in estimation the geopotential anomaly. The geostrophic volume transport through the western channel of the Korea Strait is the largest between trough area and the Tsushima Island.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.291-296
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• 2003

This study estimated surface temperature by using split-window technique and NOAA/AVHRR data was used. For surface monitoring, cloud masking procedure was carried out using threshold algorithm. The daily maximum air temperature is estimated by multiple regression method using independent variables such as satellite-derived surface temperature, EDD, and latitude. When the EDD data added, the highest correlation shown. This indicates that EDD data is the necessary element for estimation of the daily maximum air temperature. We derived correlation and experience equation by three approaching method to estimate daily maximum air temperature. 1) non-considering landcover method as season, 2) considering landcover method as season, and 3) just method as landcover. The last approaching method shows the highest correlation. So cross-validation procedure was used in third method for validation of the estimated value. For all landcover type 5, the results using the cross-validation procedure show reasonable agreement with measured values(slope=0.97, intercept=-0.30, R$^2$=0.84, RMSE=4.24$^{\circ}C$). Also, for all landcover type 7, the results using the cross-validation procedure show reasonable agreement with measured values(slope=0.993, Intercept=0.062, R$^2$=0.84, RMSE=4.43$^{\circ}C$).

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.331-337
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• 2011

We described for the production of cloud-free satellite sea surface temperature(SST) data around Northeast Asian using NOAA AVHRR(Advanced Very High Resolution Radiometer) SST data during 1990-2005. As a result of Markov model, it was found that the value of Markov coefficient in the strong current region such as Kuroshio region showed smaller than that in the weak current. The variations of average SST and regional difference of seasonal day-to-day SST in spring and fall were larger than those in summer and winter. In particular, the distribution of the regional difference appeared large in the vicinity of continental in spring and fall. The difference of seasonal day-to-day SST was also small in Kuroshio region and southern part of East Sea due to the heat advection by warm currents.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.3
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• pp.79-89
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• 2004

Remote sensing technique is a probable means to estimate distribution of actual evapotranspiration in connection with regional characteristics of vegetation and landuse. The factors controlling evapotranspiration from ground surface are air temperature, humidity, wind, radiation, soil moisture and so on. Not only the vegetation influences directly the evapotranspiration, but also these factors strongly influences the vegetation growth at the area. Therefore, it can be expected that evapotranspiration is highly correlated to vegetation condition. The normalized difference vegetation index (NDVI) showed excellent ability to get the vegetation information. The NDVI is obtained using NOAA/AVHRR have been studied as a tool for vegetation monitoring. In this paper, a simple method to estimate actual avapotranspiration is proposed based on vegetation and meteorological data.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.2
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• pp.71-81
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• 2007

One of the most important hydrologic components is evapotranspiration. It is a process by which water is evaporated from moist land surfaces and transpired into atmosphere by plants. There are many methods of estimating evapotranspiration rate and its potential such as the methods of soil-moisture sampling, lysimeter measurements, water balance, energy balance, groundwater fluctuations and evapotranspiration. But it is very difficult to estimate evapotranspiration in terms of regional discrete characteristics of topography and/or vegetation. The evapotranspiration is strongly affected by ground covering vegetation, and the degree of vegetation growth. In order to grasp vegetation condition over a vast study area, NDVI (Normalized Difference Vegetation Indices) calculated from the data obtained from NOAA/AVHRR were utilized. Through multi-regression analysis, we developed a model equation to estimate the evapotranspiration using NDVIs and temperature data.

• Journal of the Korean Association of Geographic Information Studies
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• v.3 no.3
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• pp.20-30
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• 2000

Average annual NDVI values from the NOAA/NASA Pathfinder AVHRR Land Data Sets from 1982 to 1994 showed comprehensive systematic displacement patterns in Asia. Inter-annual growing season data, however, did not show such systematic patterns. The most likely cause for the abrupt displacements, which appear especially in 1982, 1989 and 1990, may be changes in satellite sensors, although global warming, El Ni$\tilde{n}$o-Southern Oscillation events, changes in processing algorithms, and changes in land-use patterns in various parts of Asia may also play some role. The results suggest that researchers must be extremely careful in their inter-annual global change research, since direct use of the raw data could cause unexpected results. Growing-season NDVI shows decreases throughout most of Southeast Asia and modest gains in northern China and some parts in India, which could be related to land-use and land-cover changes.

• Water for future
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• v.29 no.5
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• pp.203-214
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• 1996

Quantifying water balance components is crucial to understanding the basic hydrology and hydrochemistry. An importance of water balance has been suggested in order to grasp actual condition of water resources and environmental changes including climatic changes. The present paper proposes an evaluation method of the water balance components based on vegetation monitoring from remote sensing data. In this study, evapotranspiration model adopts a directmethod by using NDVI (Normalized Difference Vegetation Index) calculated from NOAA/AVHRR data and the detailed description of water balance by using the evapotranspiration in all over the Korean Peninsula. Areal distribution data sets of evapotranspiration in all over the Korean Peninsula. Areal distribution data sets of evapotranspiration, runoff ratio, water surplus and deficit are produced using NDVI and simplified water balance model. This method enables to discuss the hydrological problems for North Korea where enough meteorological and hydrological data are unavailable.

• Journal of the Korean GEO-environmental Society
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• v.9 no.6
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• pp.43-51
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• 2008

This study is to evaluate the NPP (Net Primary Production) distribution in the Geum River basin from NOAA/AVHRR satellite imagery data. It is supposed that the natural vegetation condition and the NPP has the linear relationship. The NPP from natural vegetation increases proportional to the annual net radiation (Rn), where radiative dryness index (RDI) is a proportional constant connecting net radiation to NPP. Normalized Difference Vegetation Index (NDVI) is used for monitoring vegetation change, and iNDVI (integrated NDVI) for annual analysis. The iNDVI has a close relation to Rn and NPP, which can be used effectively for estimating NPP distribution of where the meteorological data is unavailable. The purpose of this study is to propose a simple method to get NPP in the Geum river basin.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.1
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• pp.20-27
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• 2004

The hydro-dynamical and ecological coupled model were applied in the Tokyo Bay, to evaluate the flow pattern including water quality parameters and the distribution of biomass flux, and to compare with the results obtained from the satellite data during March 2001. The flow pattern and salinity distribution obtained from the present model were nearly identical with those of the previous studies. SST from NOAA/AVHRR was $2.5^{\circ}C$ higher than model results in the mouth of bay and $0.5^{\circ}C$ lower than model results in the inner bay, respectively. It was found that the concentration of chlorophyll-a estimated from SeaWiFS was considerably higher than that of model result, regardless similar distribution pattern. This disagreement will be studied through the more elaborate investigation in the future.

• Korean Journal of Remote Sensing
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• v.11 no.1
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• pp.31-45
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• 1995

The values of brightness temperature difference (BTD) between 11um and 12um infrared channels may reflect amounts of low-level water vapor and cloud types due to the different absorptivity for water vapor between two channels. A simple method of classifying cloud types at night was proposed. Two-dimensional histograms of brightness temperature of the 11um channel and the BTD between the split window data over subareas around characteristic clouds such as Cb(cumulonimbus), Ci(cirrus), and Sc(stratocumulus) was constructed. Cb, Ci and Sc can be classified by seleting appropriate thresholds in the two-dimensional histograms. And we can see amounts of low-level water vapor in clear area as well as cloud types in cloudy area in the BTD image. The map of cloud types and low-level water vapor generated by this method was compared with 850hPa and 1000hPa relative humidity(%) of numerical analysis data and nephanalysis chart. The comparisons showed reasonable agreement.