• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.25-28
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• 2002

The aim of the present study was the evaluation of methods for estimating the vegetation information in the field on the basis of spectral reflectance measured farm field, in particular the estimation of Leaf Area Index(LAI). Variability in tissue optical properties was wavelength-dependent. For rice and bean, the lowest variation was in the visible spectral region and the highest in the near-infrared. The structural attributes of ecosystems determine the relative contribution of tissue and canopy factors that drive variation in a reflectance signal.

• Journal of Life Science
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• v.12 no.5
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• pp.544-548
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• 2002

The object of this study was to investigate nitrogen fixation activity of rhizobium inoculated at seed coat when drought condition was applied in flowering period of soybean c.v. Samnamkong. The rhizobia used in this experiment were indigenous rhizobium, R2l4, RJl-29, USDA110 and USDA122. The experiment was done with 1/2000 Wagner pots in laboratory and greenhouse and was tested in completely randomized design with four replications. Nitrogen fixation activity in coventional culture was the highest in R2l4 and indigenous rhizobium among the five rhizobia strains. As given drought condition from flowering to maturity, nitrogen fixation activity was higher in R2l4 and RJl-29 than indigenous rhizobium. Leaf area and relative index (drought/convention) of pod weight were higher in USDA122, RJl-29 and R2l4 than indigenous rhizobium as given drought condition from flowering to maturity. High positive correlation was observed between nitrogen fixation activity of rhizobium and relative index(drought/convention) of pod weight. High negative correlation was observed between respiration of plant and relative index (drought/convention) of leaf area.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.384-398
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• 2015

In this paper, the high-resolution Weather Research and Forecasting/Noah-MultiParameterization (WRF/Noah-MP) modeling system is configured for the Cheongmicheon Farmland site in Korea (CFK), and its performance in land and atmospheric simulation is evaluated using the observed data at CFK during the 2014 special observation period (21 August-10 September). In order to explore the usefulness of turning on Noah-MP dynamic vegetation in midterm simulations of surface and atmospheric variables, two numerical experiments are conducted without dynamic vegetation and with dynamic vegetation (referred to as CTL and DVG experiments, respectively). The main results are as following. 1) CTL showed a tendency of overestimating daytime net shortwave radiation, thereby surface heat fluxes and Bowen ratio. The CTL experiment showed reasonable magnitudes and timing of air temperature at 2 m and 10 m; especially the small error in simulating minimum air temperature showed high potential for predicting frost and leaf wetness duration. The CTL experiment overestimated 10-m wind and precipitation, but the beginning and ending time of precipitation were well captured. 2) When the dynamic vegetation was turned on, the WRF/Noah-MP system showed more realistic values of leaf area index (LAI), net shortwave radiation, surface heat fluxes, Bowen ratio, air temperature, wind and precipitation. The DVG experiment, where LAI is a prognostic variable, produced larger LAI than CTL, and the larger LAI showed better agreement with the observed. The simulated Bowen ratio got closer to the observed ratio, indicating reasonable surface energy partition. The DVG experiment showed patterns similar to CTL, with differences for maximum air temperature. Both experiments showed faster rising of 10-m air temperature during the morning growth hours, presumably due to the rapid growth of daytime mixed layers in the Yonsei University (YSU) boundary layer scheme. The DVG experiment decreased errors in simulating 10-m wind and precipitation. 3) As horizontal resolution increases, the models did not show practical improvement in simulation performance for surface fluxes, air temperature, wind and precipitation, and required three-dimensional observation for more agricultural land spots as well as consistency in model topography and land cover data.

• Korean Journal of Environmental Agriculture
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• v.8 no.2
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• pp.128-135
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• 1989

To find the effects of solar energy into the rice canopy and its balance on the rice plant growth, a Tongil type rice, Raekyeong and a japonica rice, Koganebare were used with four levels of nitrogen fertilizer application, 6, 10, 14, and 18kg $l0a^{-1}$ in Chigugo, Japan. The micrometerosological data, the solar radiation and absorbed solar radiation by the rice plants, and leaf area index on cardinal growth stage of the rice community were measured. The results are as follows : Raekyeong showed increased LAI by increased nitrogen fertilizer application rates, and larger LAI than Koganebear. 1. There was no difference in total dry weight till 20 days after transplanting regardless of nitrogen levels in the same variety, after that, however, Raekyeong showed higher dry matter productions for the same durations than Koganebare. 2. In early growth stage of transplanting rice, reflection ratio of solar radiation above the crop canogy was about 6%, however, it was increased up to 20% by the increased LAI at heading date. 3. In high levels of nitrogen application plots, LAI were increased so that values were decreased. 4. Relationship between the amount of absorbed radiation by plants and its dry matter production was linearly significant. Higher levels of nitrogen application produced higher dry matter in Raekyeong, however, in lower level, the dry matter production pattern was almost similar between both rice cultivars.

• Journal of Korean Society of Forest Science
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• v.96 no.4
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• pp.438-447
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• 2007

The purpose of this study was to understand the ecosystem structure and function and soil water changes in Tricholoma matsutake producing pine stands. The investigated stands were pine forest in Sogrisan National Park in Chungbuk-do of Korea. For the purpose we investigated main vegetation, leaf area index(LAI) as ecosystem structural factors and measured photosynthesis, transpiration, xylem water potential, and soil water changes as ecosystem functional factors. Vertical vegetation structure of the site was composed of Pinus densiflora as a overstory species, Quercus mongolica as midstory, Rhododendron mucronulatum, R. schlippenbachii and Fraxinus sieboldiana as understory ones. In the stands LAI was 3.8 during June to September, 2.6 in October and 2.1 during November to April. Photosyntheses of the trees were 6.0 to $7.0{\mu}mol\;CO_2/m^2/s$ in August, and for P. densiflora about $4.0{\mu}mol\;CO_2/m^2/s$ and for Q. mongolica $2.0{\mu}mol\;CO_2/m^2/s$ in mid October. However, R. mucronulatum stopped fixing $CO_2$ and F. sieboldiana shed off the leaves already in mid October. Transpirations were 2.5 to $3.5mmol\;H_2O/m^2/s$ in late August and about $1.0mmol/H_2O/m^2/s$ in mid October. Plant water potentials were -10 to -22 bars for P. densiflora and -5 to -12 bars for the other woody species. The lowest potentials was in late August and highest in late October. Soil water in the stand was closely related to topography. Soil water contents were 7 to 11% at the ridge, 8 to 15% at the hillside and 11 to 19% at the base. Soil temperatures were 0.2 to $0.4^{\circ}C$ higher in T. matustuake colony than noncolony. Mid September soil temperature decreased to $19^{\circ}C$ at which T. matsutake forms primordia. In T. matsutake colony soil moisture was 0.5 to 2.0% lower due to metabolism for consuming water. We suggest that the complicate relationships between ecosystem structure and function in Tricholoma matsutake producing pine stand need to be further investigated.

• Korean Journal of Remote Sensing
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• v.14 no.1
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• pp.83-94
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• 1998

To have a basic idea on the spectral reflectance signature in paddy rice canopy, we measured spectral reflectance from paddy rice canopy(Ilpumbyeo) using spectroradiometer (GER Inc. SFOV : 0.35~2.50 ${\mu}{\textrm}{m}$) in situ weekly or biweekly from transplanting to ripening stage. Spectral reflectance of the visible range (0.4~0.7 ${\mu}{\textrm}{m}$) was decreased to below 5% and then slightly increased again after heading stage in rice canopy. Meanwhile spectral reflectance of the near-infrared range (0.7~1.1 ${\mu}{\textrm}{m}$) was increased to 40~50% and then decreased a great deal after panicle initiation stage in rice canopy. Landsat TM equivalent band set ($\bar{p}$$_{TMi}$) was created by averaging spectral reflectance values to the real TM bands. Correlation analysis between the rice crop variables (LAI, total dry matter) and TM equivalent band set ($\bar{p}$$_{TMi}$) showed that LAI and total dry matter of rice were highly correlated with visible bands such as $\bar{p}$$_{TM1}$, $\bar{p}$$_{TM2}$, and $\bar{p}$$_{TM3}$. Ratio values ($\bar{p}$$_{TMi}$/$\bar{p}$$_{TMi}$) such as $\bar{p}$$_{TM4}$/$\bar{p}$$_{TM2}$ were also highly correlated with rice crop variables such as LAI and total dry matter.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.875-889
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• 2021

This study compares and analyzes the Soil and Water Assessment Tool (SWAT) and Terra MODIS (Moderate Resolution Imaging Spectroradiometer) as coniferous, deciduous and mixed forest with Yongdam Dam upstream (904.4 km²). The hydrologic evaluation period was set to 10 years from 2010 to 2019, and the applicability of the 8-day MOD15A2 Leaf Area Index (LAI) data, 3 TDR (Time Domain Reflectometry) (GB, JC, CC), and 1 Flux Tower (DU) evaporation volume (YDD) data was simulated. As a result, the R² of coniferous forest, deciduous forest and mixed forest are 0.95, 0.89, 0.90, soil moisture and evaportranspiration stations R² were analyzed at 0.50 to 0.55 and 0.51, respectively, with R² at 0.74, RMSE 2.75 mm/day, NSE 0.70 and PBIAS 14.3% for Yongdam inflow. Based on the calibrated and validated watersheds, the annual average evaportranspiration was calculated as coniferous 469.7 mm, deciduous 501. mm and 511.5 mm mixed forest, total runoff were estimated at coniferous 909.8 mm, deciduous 860.6 mm and 864.2 mm mixed forest. In the case of annual average evaportranspiration, it was evaluated that deciduous were high, but in the case of streamflow, it was evaluated that coniferous were high. Unlike other hydrologic with similar patterns throughout the year, the average annual evapotranspiration was about 7% higher than coniferous due to the higher evapotranspiration of deciduous with high leaf area index in summer and fall. In addition, deciduous were 9% and 6% higher for surface runoff and lateral flow, but the groundwater of coniferous was 77% higher. Therefore, it was confirmed that the total runoff was in order of coniferous, mixed forest, and deciduous.

• The Korean Journal of Ecology
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• v.28 no.4
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• pp.215-222
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• 2005

MODIS (Moderate Resolution Image Spectrometer) is a core satellite sensor boarded on Terra and Aqua satellite of NASA Earth Observing System since 1999 and 2001, respectively. MODIS LAI, FPAR, and GPP provide useful means to monitor plant phonology and material cycles in terrestrial ecosystems. In this study, LAI, FPAR, and GPP in Korea were evaluated and errors associated with cloud contamination on MODIS pixels were eliminated for years $2001\sim2003$. Three-year means of cloud-corrected annual GPP were 1836, 1369, and 1460g C $m^{-2}y^{-1}$ for evergreen needleleaf forest, deciduous broadleaf forest, and mixed forest, respectively. The cloud-originated errors were 8.5%, 13.1%, and 8.4% for FPAR, LAI, and GPP, respectively. Summertime errors from June to September explained by 78% of the annual accumulative errors in GPP. This study indicates that cloud-originated errors should be mitigated for practical use of MODIS vegetation products to monitor seasonal and annual changes in plant phonology and vegetation production in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.6
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• pp.457-462
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• 2004

Lodging is one of the most serious problems in soybean cultivation. Therefore, improved cultural methods to reduce lodging as well as to increase photosynthetic ability should be mostly desirable to increase soybean production. The test variety was 'Hwangkeumkong' which was pinched at V7 stage. The greatest difference in canopy height between rows was shown when every other row was pinched, which also recorded the most effective reduction in lodging. The 9th leaf of soybean plants in non-pinching rows of alternative non-pinching and pinching plot showed the highest photosynthetic ability due to the greatest difference in canopy height. Although leaf area index was higher in pinched rows in average after 17 August, alternative pinching of every other row recorded the highest LAI on 5 September. Alternative pinching of every other row resulted $2\~14\%$ higher yield than non-pinching or complete pinching due to the increases of number of grains in the upper part of main stem and average grain weight of non-pinching rows and in alternative pinching.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.107-114
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• 2007

Establishments of the seedlings inside the natural forest from adjacent artificial forests would be an important factor in forest stand dynamics. This study was conducted to see the invasion of Korean pine (Pinus koraiensis) seedlings which is not native in this region, into the natural deciduous broad-leaved forest in Gwangneung, Korea. There is no mother tree at the I ha study site while the number of naturally regenerated P. koraiensis seedlings was 345 trees and 56% of them were clumped with more than two seedlings at each point. Applying the image segmentation method to IKONOS satellite image of January, 2003, the distance from the center of 1 ha study site to the nearest mother tree and plantation of Korean pine were 200 m and 270 m, respectively. The average height and root-collar diameter of the seedlings were 34 em and 7 mm, respectively and the age of 207 seedlings (60%) were below 5 years old. Most abundant range of soil moisture gradient and LAl (leaf area index) were from 16 to 20% and those of LAI were from 3.1 to 3.5. To understand the dynamics and seed dispersal pattern of Korean pine in the Gwangneung natural deciduous broad-leaved forests, additional studies not only long-term monitoring of growth and mortality of naturally regenerated Korean pine seedlings but also application of stable isotope analysis and molecular genetic techniques was recommended.