• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.133-149
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• 2022

Existing domestic studies on estimating rice yield were mainly implemented at the level of cities and counties in the entire nation using MODIS satellite images with low spatial resolution. Unlike previous studies, this study tried to estimate rice yield at the level of eup-myon-dong in Gimje-si, Jeollabuk-do using Sentinel-2 satellite images with medium spatial resolution, rainfall and soil data, and then to evaluate its accuracy. Five vegetation indices such as NDVI, LAI, EVI2, MCARI1 and MCARI2 derived from Sentinel-2 images of August 1, 2018 for Gimje-si, Jeollabuk-do, rainfall and paddy soil-type data were aggregated by the level of eup-myon-dong and then rice yield was estimated with gamma generalized linear model, an expanded variant of multi-variate regression analysis to solve the non-normality problem of dependent variable. In the rice yield model finally developed, EVI2, rainfall days in September, and saline soils ratio were used as significant independent variables. The coefficient of determination representing the model fit was 0.68 and the RMSE for showing the model accuracy was 62.29kg/10a. This model estimated the total rice production in Gimje-si in 2018 to be 96,914.6M/T, which was very close to 94,470.3M/T the actual amount specified in the Statistical Yearbook with an error of 0.46%. Also, the rice production per unit area of Gimje-si was amounted to 552kg/10a, which was almost consistent with 550kg/10a of the statistical data. This result is similar to that of the previous studies and it demonstrated that the rice yield can be estimated using Sentinel-2 satellite images at the level of cities and counties or smaller districts in Korea.

• Journal of the Korean Mathematical Society
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• v.38 no.3
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• pp.683-695
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• 2001

In this paper we are concerned with theoretical properties of gap functions for the extended variational inequality problem (EVI) in a general Banach space. We will present a correction of a recent result of Chen et. al. without assuming the convexity of the given function Ω. Using this correction, we will discuss the continuity and the differentiability of a gap function, and compute its gradient formula under tow particular situations in a general Banach space. Our results can be regarded as infinite dimensional generalizations of the well-known results of Fukushima, and Zhu and Marcotte with soem modifications.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.193-196
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• 2005

As global warming proceeds, South Eastern Asia is undergoing drought, and the harshness of drought in the middle area of Korea is increasing. Especially, there has been the worst spring drought in 2001 since the first meteorological observation, and the damages caused by that drought are being ana lysed in various ways. In this study, spectral indices derived from satellites are used to examine 2001 spring drought, and the application of MODIS Data products as the quantitative tool to analyse drought in the future is examined.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.405-407
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• 2003

An attempt has been in this study to delineate the characteristics of spectral signatures of the vegetation in terms of various VIs, particularly made the Normalized Difference Vegetation Index(NDVI), Modified Soil Adjusted Vegetation Index2(MSAVI2) and Enhanced Vegetation Index(EVI). Multitemporal SPOT-4 VEGETATION data from 1998 to 2002 have been used for the analysis. They have been compared with each other for their similarities and differences. The correlations between the vegetation indices observed at various degree of vegetation coverage during their different stages of growth were examined. All of the VIs have shown qualitative relationships to variations in vegetation. Apparently, the NDVI and MSAVI2 are highly correlated for all of the temporal changes, representing the different stages of phenology.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.482-484
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• 2003

GLI on boarded ADEOS-II satellite allows us to observe vegetation status in the two different resolutions simultaneously, because of thirty 1km resolution channels and six 250m resolution channels. There are four GLI land higher level products from these channels ; those are PGCP (Precise Geometric Correction Parameter), L2A_LC (TOA reflectance), ACLC (atmospheric corrected reflectance), and VGI (NDVI and EVI). This paper shows ADEOS-II GLI land data processing, and some of the latest results.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2013.11a
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• pp.25-25
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• 2013

식생의 생물계절학적 특성은 지표면과 대기의 에너지와 물 순환에 큰 영향을 미친다. 일반적으로 상층군락과 하층군락의 식생은 미기후의 차이 등에 의해 서로 다른 생물계절학적 특성을 가진다. 이러한 식생의 생물계절학적 특성은 반사도 관측을 통해 추정할 수 있다. 과거부터 원격탐사 기법을 활용하여 식생의 생물계절학적 특성을 추정하는 많은 연구가 수행되어 왔다. 그러나 대부분의 연구는 상층군락과 하층군락의 반사특성을 구분하지 않았다. 본 연구에서는 상층군락과 하층군락 식생의 생물계절학적 특성을 구분하여 탐지하기 위해 red, green, blue 그리고 near-infrared 의 네 가지 파장대를 가진 LED 센서를 이용하였다. LED 센서는 광릉 시험림 내의 활엽수림과 침엽수림 관측지에 서로 다른 네 군데의 높이에 설치되어 각 파장대의 반사도를 산출하였다. 또한 반사도를 이용하여 세 가지 식생지수(NDVI, EVI, Greenness index)를 산출하여 상층식생과 하층식생의 개엽기를 추정하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.85-85
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• 2016

가뭄은 다른 어떤 기상재해보다 광범위하고 긴 시간에 걸쳐 큰 피해를 초래할 뿐만 아니라 많은 변수들이 복합적으로 작용하여 발생하기 때문에 그 발생 원인을 이해하기 힘들다. 따라서 가뭄에 의한 피해를 최소화하기 위해서는 중, 장기적인 가뭄의 예측이 필요하며, 가뭄을 예측한다는 것은 가뭄의 발생의 시공간 분포와 발생 원인을 정확히 이해하는데서 시작할 수 있다. 현재 우리나라는 기후변화로 인한 이상기후의 영향으로 마른장마, 봄 가뭄 등 이상가뭄이 빈발하고 발생되고 있으며, 90년 이후로 남부지역을 중심으로 겨울에서 봄까지의 가뭄인 횟수가 점점 증가하고 있는 실정이다. 본 연구에서는 가뭄의 시공간적으로 분석하기 위하여 Terra의 MODIS 원격탐사 자료를 활용하였으며, 한반도를 대상으로 가뭄의 정량적 평가를 실시하고자 하였다. 본 연구의 성과는 제한된 관측정보를 통한 시공간 분석의 한계점을 가지고 있지만 가뭄 피해에 대한 현실적인 대책 및 적응전략 수립에 횔용 가능성이 높을 것으로 기대된다.

• Asia pacific journal of information systems
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• v.31 no.3
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• pp.378-391
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• 2021

The low use of e-vehicles in Yogyakarta City and Pekanbaru City is an essential issue for local governments to maximize e-government policies in both regions. The purpose of this research is to analyze people's attitudes and factors influencing the community of e-Samsat (e-Vehicle tax) users in developing the UMEGA theory, namely technology and government trust. This is a quantitative research based on the philosophy of positivism, which is used to examine populations and individual samples. Data were collected using research instruments and quantitatively analyzed. Furthermore, the hypothesis of the obtained data was tested using SEM-PLS. The results showed that social influence does not affect attitudes of e-Samsat (e-Vehicle tax) users. Furthermore, the study showed that the development of umega theory by adding variables of trust in technology and government affects people's behavior in using e-Samsat services.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.509-520
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• 2012

The objective of this study was to estimate rice yield in Korea using satellite and meteorological data such as sunshine hours or solar radiation, and rainfall. Terra and Aqua MODIS (The MOderate Resolution Imaging Spectroradiometer) products; MOD13 and MYD13 for NDVI and EVI, MOD15 and MYD15 for LAI, respectively from a NASA web site were used. Relations of NDVI, EVI, and LAI obtained in July and August from 2000 to 2011 with rice yield were investigated to find informative days for rice yield estimation. Weather data of rainfall and sunshine hours (climate data 1) or solar radiation (climate data 2) were selected to correlate rice yield. Aqua NDVI at DOY 233 was chosen to represent maximum vegetative growth of rice canopy. Sunshine hours and solar radiation during rice ripening stage were selected to represent climate condition. Multiple regression based on MODIS NDVI and sunshine hours or solar radiation were conducted to estimate rice yields in Korea. The results showed rice yield of $494.6kg\;10a^{-1}$ and $509.7kg\;10a^{-1}$ in 2011, respectively and the difference from statistics were $1.1kg\;10a^{-1}$ and $14.1kg\;10a^{-1}$, respectively. Rice yield distributions from 2002 to 2011 were presented to show spatial variability in the country.

• Journal of Environmental Impact Assessment
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• v.26 no.5
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• pp.315-330
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• 2017

The aim of this study is to examine the damage of plants in the islands due to the habitat and feeding of European rabbit (Oryctolagus cuniculus) and to suggest future management plan. The survey area Beomseom Island is found to be a vegetation distribution type that was formed secondary by the exposure of artificial interference except for evergreen vegetation distribution and European rabbit showed high habitat track density mainly in the lumbering area. Kkamakseom Island was identified as a severe vegetation distribution area due to interference, and European rabbit showed high habitat track density around deciduous broad leaved forests. Feeding plants of European rabbit was identified as a total of 12 families 17 breeds. Total 9 families 11 breeds were found in Beomseom Island while 5 families 6 breeds were found in Kkamakseom where most available food resources were loss to European rabbit. As for vegetation index of Beomseom Island, about 6.6% of total island area was declined and the vegetation index of Kkamakseom Island was reduced at most area of the island. In Kkamakseom Island, the area where EVI decreased to less than -0.008 unit/yr was reduced to 5.2%, and the area where it was reduced to -0.008 to -0.006 unit/yr in total was 13.32% of the total area. Thus, it was estimated to be seriously damaged by vegetation. Therefore, immediate management is required.