• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.2
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• pp.78-82
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• 2022

Phenology determines the timing of crop development, and the timing of phenological events is strongly influenced by the temperature during the growing season. In process-based model, leaf area is simulated dynamically by coupling of morphology and phenology module. Therefore, the prediction of leaf appearance rate and final leaf number affects the performance of whole crop model. The dataset for the model equation was collected from SPA R chambers with five different temperature treatments. Beta distribution function (proposed by Yan and Hunt (1999)) was used for describing the leaf appearance rate as a function of temperature. The optimum temperature and the critical value were estimated to be 26.0℃ and 35.3℃, respectively. For evaluation of the model, the accumulated number of onion leaves observed in a temperature gradient chamber was compared with model estimates. The model estimate is the result of accumulating the daily increase in the number of onion leaves obtained by inputting the daily mean temperature during the growing season into the temperature model. In this study, the coefficient of determination (R²) and RMSE value of the model were 0.95 and 0.89, respectively.

• Research in Plant Disease
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• v.17 no.3
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• pp.317-325
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• 2011

Bacterial pustule of soybean (Glycine max) caused by Xanthomonas axonopodis pv. glycines is one of the most prevalent bacterial diseases of soybean in Korea, where it causes considerable yield loss. This study was carried out to develop yield prediction model for bacterial pustule by analyzing correlation between the percentage of diseased leaf area and yield. The severe disease incidence of soybean bacterial pustule caused yield losses by 19.8% in 2006 and 16.8% in 2007, respectively. Severity of bacterial pustule greatly affected on 100 seed weight and yield, but did not on stem length, number of branches per plant, number of pods per plant, number of seeds per plant. On the other hand, correlation coefficients between diseased leaf area and yield were $-0.93^*$('06) and $-0.77^*$('07), respectively. The regression equation obtained by analyzing correlation between the percentage of diseased leaf area and yield loss in 2006 and in 2007 was y = -3.2914x + 348.19($R^2$ = 0.8603) and y = -2.9671x + 302.08($R^2$ = 0.9411), respectively. These results will be helpful in estimating losses on a field-scale and thereby predicting the production of soybean.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.2
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• pp.173-181
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• 1997

To estimate the leaf area index(LAI) of rice plant by non-destructive method, spectral reflectance from rice plant canopy was measured by using the spectroradiometer (LI-1800, LICOR Inc.) with one week interval during the rice growing season at Suwon paddy field in 1993. LAI of two medium late maturing varieties, Daechungbyeo and Ilpumbyeo, and one early maturing variety, Jinbubyeo, were observed and compared with those estimated by vegetation index. The reflectance(R) of visible wavelength remained less than 0.1 over entire growing season, but that of near infrared wavelength remained from 0.1 to 0.5 with the significant positive correlation with LAI. Vegetation index determined by the reflectance of visible against near infrared wavelength showed high correlation with LAI of rice canopy. Vegetation index derived from wide band ratio, NIR(720~1, 100nm) /Blue(400~500nm), showed the highest correlation coefficient with LAI. Vegetation index derived from narrow band(10nm interval) ratio, R910/R460, from transplanting to heading stage corresponded well to measured values (Y=0.16799X-0.79776 ; $R^2$=0.94). But another vegetation index, NIR(720~1, 100nm) /Red (600~700nm), showed higher correlation with LAI than NIR /Blue did from heading stage to maturity.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.3
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• pp.162-178
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• 2017

Remote sensing can be used to provide information about the monitoring of crop growth condition. Recently Unmanned Aerial Vehicle (UAV) technology offers new opportunities for assessing crop growth condition using UAV imagery. The objective of this study was to assess weather UAV aerial images are suitable for the monitoring of highland Kimchi cabbage. This study was conducted using a fixed-wing UAV (Model : Ebee) with Cannon S110, IXUS/ELPH camera during farming season from 2015 to 2016 in the main production area of highland Kimchi cabbage, Anbandegi, Maebongsan, and Gwinemi. The Normalized Difference Vegetation Index (NDVI) by using UAV images was stable and suitable for monitoring of Kimchi cabbage situation. There were strong relationships between UAV NDVI and the growth parameters (the plant height and leaf width) ($R^2{\geq}0.94$). The tendency of UAV NDVI according to Kimchi cabbage growth was similar in the same area for two years (2015~2016). It means that if UAV image may be collected several years, UAV images could be used for estimation of the stage of growth and situation of Kimchi cabbage cultivation.

• Journal of Bio-Environment Control
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• v.25 no.2
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• pp.123-132
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• 2016

The importance of energy saving technology for managing greenhouse was recently highlighted. For practical use of energy in greenhouse, it is necessary to simulate energy flow precisely and estimate heating/cooling loads of greenhouse. So the main purpose of this study was to develope and to validate greenhouse energy model and to estimate annual/maximum energy loads using Building Energy Simulation (BES). Field experiments were carried out in a multi-span plastic-film greenhouse in Jeju Island ($33.2^{\circ}N$, $126.3^{\circ}E$) for 2 months. To develop energy model of the greenhouse, a set of sensors was used to measure the greenhouse microclimate such as air temperature, humidity, leaf temperature, solar radiation, carbon dioxide concentration and so on. Moreover, characteristic length of plant leaf, leaf area index and diffuse non-interceptance were utilized to calculate sensible and latent heat exchange of plant. The internal temperature of greenhouse was compared to validate the greenhouse energy model. Developed model provided a good estimation for the internal temperature throughout the experiments period (coefficients of determination > 0.85, index of agreement > 0.92). After the model validation, we used last 10 years weather data to calculate energy loads of greenhouse according to growth stage of greenhouse crop. The tendency of heating/cooling loads change was depends on external weather condition and optimal temperature for growing crops at each stage. In addition, maximum heating/cooling loads of reference greenhouse were estimated to 644,014 and $756,456kJ{\cdot}hr^{-1}$, respectively.

• Korean Journal of Environmental Agriculture
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• v.8 no.1
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• pp.30-36
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• 1989

To determine irrigated water temperature under the rice plant canopy, micrometeorological elements air temperature, relative humidity, water temperature, solar radiation, and the rice leaf area index the rice plant canopywere measured. Water temperature under the canopy was also estimated from these data. The results are as follows ; 1. Maximum and minimum temperatures of water in the paddy field were higher about $1-2^{\circ}C$ than those of air temperature. 2. Mean water temperature under the canopy became lower than mean air temperature when the leaf area indices were greater than 4, because of decreased light penetration rates 3. Penetration amounts of net radiation under the canopy can be estimated by an exponential equation 4. Estimated water temperatures under the canopy by a combination method model was adaptable in Suweon, a plain area, but its accuracy was lower in Jinbu, an alpine area.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.4
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• pp.1-13
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• 2005

In the process of a hydrology circulation, evapotranspiration is considered a very important factor to build a plan for the development of water resources and to operate water resources system. This study purposes to estimate daily potential evapotranspiration quantity in consideration of energy factors of the surface by using spatial information such as Landsat TM (ETM+) data, DEM and Landcover. Kyounan-cheon, Han River is selected as a target area, and landcover is divided by vegetation and non-vegetation covered area. Penman-Monteith equation which considers leaf-area index is used to estimate potential evapotranspiration quantity of vegetation covered area. The combination method (energy burget and aerodynamic method) is used in non-vegetation covered area. Among the input data for estimating potential evapotranspiration, NDVI, SR and Albedo is formed by Landsat, TM and ETM+ from 1986 through 2002. ground heat flux is estimated by using NDVI distribution map, LAI distribution map is drawn by using SR distribution map. The result of estimation shows that the average potential evapotranspiration in the whole basin is about 1.8-3.2mm/day per each cell. THe results of estimating potential evapotranspiration quantity by each landcover are as follows; water surface 3.6-4.9mm/day, city 1.4-3.1mm/day, bareland 1.4-3.5mm/day, grassland 1.7-3.7mm/day, forest 1.7-3.0mm/day and farmland 1.8-3.6mm/day. The potential evapotranspiration quantity is underestimated in comparison with observed evaporation data by evaporation pan, but it is considered that it has physical propriety.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.420-428
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• 2016

For more than 50 years, satellite images have been used to monitor crop growth. Currently, unmanned aerial vehicle (UAV) imagery is being assessed for analyzing within field spatial variability for agricultural precision management, because UAV imagery may be acquired quickly during critical periods of rapid crop growth. This study refers to the derivation of growth estimating equation for highland Kimchi cabbage using UAV derived normalized difference vegetation index (NDVI) and agro-meteorological factors. Anbandeok area in Gangneung, Gangwon-do, Korea is one of main districts producing highland Kimchi cabbage. UAV imagery was taken in the Anbandeok ten times from early June to early September. Meanwhile, three plant growth parameters, plant height (P.H.), leaf length (L.L.) and outer leaf number (L.N.), were measured for about 40 plants (ten plants per plot) for each ground survey. Six agro-meteorological factors include average temperature; maximum temperature; minimum temperature; accumulated temperature; rainfall and irradiation during growth period. The multiple linear regression models were suggested by using stepwise regression in the extraction of independent variables. As a result, $NDVI_{UAV}$ and rainfall in the model explain 93% of the P.H. and L.L. with a root mean square error (RMSE) of 2.22, 1.90 cm. And $NDVI_{UAV}$ and accumulated temperature in the model explain 86% of the L.N. with a RMSE of 4.29. These lead to the result that the characteristics of variations in highland Kimchi cabbage growth according to $NDVI_{UAV}$ and other agro-meteorological factors were well reflected in the model.

• Korean Journal of Organic Agriculture
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• v.13 no.4
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• pp.413-422
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• 2005

This study was carried out to investigate the effect of different mixture ratios of vermicasts on the growth of leaf beet(Beta vulgaris var. cicla), young radish (Raphanus sativus L), spinach(Spinacia oleracea) and lettuce(Lactuca sativa) The mixture of ratios of vermicast(fermented pig manure with sawdust) and peatmoss were 100%+0%, 60%+40%, 40%+60% and 0%+100%(control), respectively. The bulk density, particle density, pH, electrolytic conductivity, ash, total nitrogen, cation exchange capacity, available phosphorous and exchangeable cations increased significantly compared to those grown in the 100% of peatmoss(control). The significantly higher values of plant length, leaf area, shoot dry weight, root weight, root length and biological yield obtained were $40{\sim}100%$ and 40% of vermicast in leaf beet and lettuce, respectively. The young radish and spinach showed that significantly differences of shoot dry weight, root weight and biological yield in the mixture ratios of vermicast were $40{\sim}60%$ and 40% in young radish and spinach, respectively.

• Korean Journal of Plant Resources
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• v.8 no.2
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• pp.175-182
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• 1995

This study was carried out to investigate the check shelling distribution of Lindera erythrocarpa Makino in Kanghwa Island, MT. Suri, Kyunggido and MT. Kaya, Chungchongnamdo. The results were as follows : The total distribution area of Linedra erythrocarpa where are Jeondeung temple and Jugsu temple Kanghwa Island, MT. Suri, Kyunggido and MT. Kaya, Chungchongnamdo was 344.4ha and the total number of Linedra erythrocarpa was 3,224. The total number of femle Linedra erythrocarpa was625(22.2%) except the seedlings under 2cm of DBH(Diameter breast of height). For the estimation of tree age by counting of tree rings, the regression equation was Y=1.79X+9.47($R^2$=0.83, DBH=cm). The soil acidity of stands studied was $pH4.6{\sim}pH5.8$. And the soil acidity of Seoul was $pH4.2{\sim}pH4.5$ So for the Planting Linedra erythrocarpa in Seoul area, the soil acidity of planting area should be changed to $pH4.6{\sim}pH5.8$. The flower size of and female of Linedra erythrocarpa was 5.96mm, 3.66mm, respectively. The length of petiole of male and female of Linedra erythrocarpa was 5.96mm, 3.66mm, respectively. The length of petiole of male and female of Linedra erythrocarpa was 5.96mm, 3.66mm, respectively. And the number of flowers per flowering bud of male and female were 13.4, 11.2, respectively. The flowering period of Lindera erythrocarpa in Suwon was 21 days from May 2 to May 22. And The leaf continuing period of Lindera erythrocarpa in Suwon was 203 days from April 7 to October 27. And the fall-foliage color continuing period was 10 days from October 18 to October 27. The fruit continuing period of Lindera erythrocarpa in Suwon was 61 days from September 26 to November 26.