• 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 The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.89-98
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• 2004

The amount of rice yield reduction due to inundation should be estimated to analyse economic efficiency of the farmland drainage improvement projects because those projects are generally promoted to mitigate flood inundation damage to rice in Korea. Estimation of rice yield reduction will also provide information on the flood risk performance to farmers. This study presented the relationships between inundated durations and rice yield reduction rates for different rice growth stages from the observed data collected from 1966 to 2000 in Korea, and developed the rice yield reduction estimation model (RYREM). RYREM was applied to the test watershed for estimating the rice yield reduction rates and the amount of expected average annual rice yield reduction by the rainfalls with 48 hours duration, 10, 20, 50, 100, 200 years return periods.

• Smart Media Journal
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• v.12 no.9
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• pp.28-37
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• 2023

The main factor affecting the decline in rice yield is damage caused by localized heavy rains or typhoons. The method of analyzing the rice lodging area is difficult to obtain objective results based on visual inspection and judgment based on field surveys visiting the affected area. it requires a lot of time and money. In this paper, we propose the method of estimation and diagnosis for rice lodging areas using a Vision Transformer-based Segformer for RGB images, which are captured by unmanned aerial vehicles. The proposed method estimates the lodging, normal, and background area using the Segformer model, and the lodging rate is diagnosed through the rice field inspection criteria in the seed industry Act. The diagnosis result can be used to find the distribution of the rice lodging areas, to show the trend of lodging, and to use the quality management of certified seed in government. The proposed method of rice lodging area estimation shows 98.33% of mean accuracy and 96.79% of mIoU.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.461-476
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• 2013

Carnegie-Ames-Stanford Approach (CASA) model is one of the most quick, convenient and accurate models to estimate the NPP (Net Primary Productivity) of vegetation. The purposes of this study are (1) to examine the spatial and temporal patterns of vegetation NPP of the paddy field area in Korea from 2002 to 2012, and (2) to investigate how the rice productivity responded to inter-annual NPP variability, and (3) to estimate rice yield in Korea using CASA model applied to MOderate Resolution Imaging Spectroradiometer (MODIS) products and solar radiation. MODIS products; MYD09 for NIR and SWIR bands, MYD11 for LST, MYD15 for FPAR, respectively from a NASA web site were used. Finally, (4) its applicability is to be reviewed. For those purposes, correlation coefficients (linear regression for monthly NPP and accumulated NPP with rice yield) were examined to evaluate the spatial and temporal patterns of the relations. As a result, the total accumulated NPP and Sep. NPP tend to have high correlation with rice yield. The rice yield in 2012 was estimated to be 526.93kg/10a by accumulated NPP and 520.32 kg/10a by Sep. NPP. RMSE were 9.46kg/10a and 12.93kg/10a, respectively, compared with the yield forecast of the National Statistical Office. This leads to the conclusion that NPP changes in the paddy field were well reflected rice yield in this study.

• Journal of the Korean Data and Information Science Society
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• v.6 no.1
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• pp.1-11
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• 1995

The parameters in the multiplicative model $Y_{1}={\alpha}_{0}{\prod}^{p}_{k=1}X_{kj}^{{\beta}_K}v_{j}$ are usually estimated by the least squares method after logarithmic transformation, and the least square Estimator of ${\alpha}_{0}$ is known to be biased, i.e., $E(e xp(\hat{\beta}_{0})){\neq}{\alpha}_{0})$. In the present study the unbaised estimators of ${\alpha}_{0}$ are examined(1) by modifying the least squares estimator and (2) by applying the Finney's results. The variances are also compared. In addition it has been observed that multiplicative model can be used to express the relationship beetween rice yield and yield components.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.522-527
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• 1997

To find out the optimum seeding rate in corrugated water seeded rice, field experiment was carried out at Yeongdeog Substation of the National Yeongnam Agricultural Experiment Station for two years, 1994 and 1995. A rice cultivar Donghaebyeo, was seeded on May 15 with five seeding rate from 3kg /10a to 7kg /10a. The number of seedling stand per unit area was curvilinearly increased with seeding rate. In characteristics of rice plant associated with lodging, the plant height, fresh weight per tiller, Culm wall thickness and ratio of gravity center were not significantly different among seeding rates, but the breaking strength of 4th internode was slightly decreased with increasing seeding rate and thus, lodging index was generally greater at higher seeding rate than lower seeding rate. Field lodging was observed at 1~3 degree in seeding rate of 5~7kg /10a. Panicle number per unit area was generally increase with increase of seeding rate, while ratio of ripened grain was decreased with increase of spikelet number. Milled rice yield was curvilinearly increased with seeding rate. The optimum seeding rate in the highest rice yield was 4.8kg /10a in 1994, and 4.3kg /a in 1995, respectively.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.357-363
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• 2003

The objective of this study is to investigate background levels of As and heavy metals (Cd, Cu, Pb and Zn) and their dietary intakes from white rice produced at various provinces in Korea during 2000. Except Jeju-do, sixty-three rice grain samples were taken at 8 provinces and analyzed for the elements using ICP-AES after acid digestion. The average contents of hi, Cd, Cu, Pb and Zn in the samples were 0.126, 0.040, 1.96, 0.361 and 16.6 mg/kg(DW), respectively. These levels are within the ranges of worldwide average concentrations in rice grains reported by various research. Assuming the rice consumption of 256 g/day by overall households in Korea, the amount of daily intake of As, Cd, Cu, Pb and Zn by the rice were estimated to be 32.3, 10.2, 502, 92.4 and 4,250 ${\mu}g$/day, respectively. Those amount of daily intakes of the elements by the rice are within the WHO's guide for trace elements, however, rice consumption is one of the most important sources of dietary intake of As and some heavy metals in Korean population.

• Korean journal of applied entomology
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• v.27 no.1
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• pp.14-20
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• 1988

쌀바구미 생명표 통계량을 정온 조건과 실온 조건에서 산출하였다. 온일도를 단위로 하였을 때 $20^{\circ}$~ $30^{\circ}$ 범위내 정온 조건에서의 통계량은 실온 조건에서의 통계량과 유사한 차이를 보이지 않았으며 온도간의 변이는 실온에서의 간 변이와 유사하였다. 이 결과는 온일도를 시간단위로 할 때 쌀바구미의 생화사가 표준화 될 수 있음을 시사하는 것이었다. 쌀바구미는 $368pm$41.2DD에서 산란을 시작하여 $1391.0\pm$38.7DD에서 멈추는 것으로 추정되었다. 외적 자연회가졸 밀도 음가 기간과 평균세대 기간은 각각$ 0.0052\pm$0.0006/DD, $134.7\pm$15.0 DD 그리고 $715.2\pm$53.6 DD인 것으로 산출되었다.

• Research in Plant Disease
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• v.16 no.3
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• pp.306-311
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• 2010

To detect Fusarium mycotoxins, grain samples were collected from 32 rice fields all over the country and from 19 maize fields in eastern and midland provinces in Korea in 2009. Maize contamination with Fusarium species (54.9%) was higher than in rice (8.2%). Using Fusarium species specific PCR primer sets (Fg16 and VERT), 58 and 354 of total 506 isolates from maize samples were putatively identified as F. graminearum (11.5%) and F. verticillioides (70.0%), respectively. From rice samples, 276 of 315 isolates (87.8%) were putatively identified as F. graminearum but F. verticillioides was not identified. LC or LC-MS analysis of the samples revealed that fumonisin was the most commonly detected mycotoxin in maize samples but its level was below the regulation limit. Only two maize samples were contaminated with deoxynivalenol and zearalenone at the levels above the regulation limit. In rice samples, contamination with zearalenone was common but the levels were below the regulation limit. This study showed that most of the Korean maize and rice samples collected in 2009 were contaminated with Fusarium mycotoxins but the levels were below the Korean regulations for deoxynivalenol, fumonisin and zearalenone.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.2
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• pp.173-181
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• 2015

Fluxes of carbon dioxide ($CO_2$) were measured above crop canopy using the Eddy Covariance (EC) method, and emission rate of methane ($CH_4$) was measured using Automatic Open/Close Chamber (AOCC) method during the 2012-2013 barley and rice growing season in a barley-rice double cropping field of Gimje, Korea. The net ecosystem exchange (NEE) of $CO_2$ in the paddy field was analyzed to be affected by crop growth (biomass, LAI, etc.) and environment (air temperature, solar radiation, etc.) factors. On the other hand, the emission rate of $CH_4$ was estimated to be affected by water management (soil condition). NEE of $CO_2$ in barley, rice and fallow period was -100.2, -374.1 and $+41.2g\;C\;m^{-2}$, respectively, and $CH_4$ emission in barley and rice period was 0.2 and $17.3g\;C\;m^{-2}$, respectively. When considering only $CO_2$, the barley-rice double cropping ecosystem was estimated as a carbon sink ($-433.0g\;C\;m^{-2}$). However, after considering the harvested crop biomass ($+600.3g\;C\;m^{-2}$) and $CH_4$ emission ($+17.5g\;C\;m^{-2}$), it turned into a carbon source ($+184.7g\;C\;m^{-2}$).