• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.50 no.6
• /
• pp.369-377
• /
• 2005

Precise application of topdressing nitrogen (N) fertilizer is indispensible for securing high yield and good quality of rice and minimizing N losses to the environment as well. For precise N management, growth and nitrogen nutrition status (NNS) should be diagnosed rapidly and accurately. The objective of the study was to evaluate the applicability of vegetation index (VI) calculated from hyperspectral canopy reflectance measurement and SPAD reading to nondestructive in situ diagnosis of growth and NNS of rice. Canopy reflectance, SPAD read­ing, growth parameters, and NNS characteristics were measured from various N treatments to evaluate the relationships among them for two cropping seasons from 2001 to 2002. The correlation coefficient of VIs with variables of growth and NNS increased positively as rice canopy became more closed. Regardless of growth stages, VIs had significantly high correlations with LAI, shoot dry weight (DW), shoot N content and nitrogen nutrition index (NNI). Those correlation coefficients increased steadily before heading stage as rice grew up. However, tiller number and leaf N concentration showed significantly high correlations with VIs only at and after panicle initiation stage (PIS). Among the VIs, RVIgreen had significantly higher correlation with the measured parameters than the other VIs: it showed correlation coefficients greater than 0.8 with leaf and shoot N concentration and DW, and much higher coefficients greater than 0.9 with LAI, shoot N content, and NNI. At LAI of below 2.5, VIs had non-significant or low correlations with the growth and NNS indicators due to the background effects. SPAD reading had significantly high correlation with leaf N concentration and NNI at each growth stage. In addition, it had significant correlations with variables of growth and NNS at PIS and booting stage, particularly, at booting stage. Though SPAD reading had a significantly high correlation value at a given growth stage in each year, it showed very weak relationship with variables of growth and NNS when pooled across growth stages and years. In conclusion, RVIgreen was found to be the most reliable VI to estimate the growth and NNS of rice around at PIS, but SPAD reading had much limitations.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.17 no.3
• /
• pp.217-226
• /
• 2015

To investigate the distributions of BVOCs (Biogenic Volatile Organic Compounds) from mountain near mega city and their role in forest atmospheric, BVOCs and their oxidized species were measured at a 41 m tower in Mt. Taehwa during May, June and August 2013. A proton transfer reaction-mass spectrometer (PTR-MS) was used to quantify isoprene and monoterpenes. In conjunction with BVOCs, $O_3$, meteorological parameters, PAR (Photosynthetically Active Radiation) and LAI (Leaf Area Index) were measured. The average concentrations of isoprene and monoterpenes were 0.71 ppbv and 0.17 ppbv, respectively. BVOCs showed higher concentrations in the early summer (June) compared to the late summer (August). Isoprene started increasing at 2 PM and reached the maximum concentration around 5 PM. In contrast, monoterpenes concentrations began to increase 4 PM and stayed high at night. The $O_3$ maximum was generally found at 3 PM and remained high until 5 PM or later, which was concurrent with the enhancement of $O_3$. The concentrations of BVOCs were higher below canopy (18 m) than above canopy, which indicated these species were produced by trees. At night, monoterpenes concentrations were negatively correlated with these of $O_3$ below canopy. Using MEGAN (Model of Emissions of Gases and Aerosols from Nature), the emissions of isoprene and monoterpenes were estimated at 1.1 ton/year and 0.9 ton/year, respectively at Mt. Taehwa.

• Journal of Korean Society of Forest Science
• /
• v.96 no.5
• /
• pp.567-571
• /
• 2007

This study was conducted to clarify the differences in breeding bird communities between deciduous forests of Gwangneung and Mt. Namsan areas from April to August 2006. Two 10ha area were selected for territory mapping of breeding bird community in both study area. The DBH distribution of trees and average foliage profiles were significantly different between study areas. Also, breeding bird communities were different. Number of breeding species and pairs, breeding density, and bird species diversity were higher in Gwangneung area than in Mt. Namsan area. When examining relationship between forest habitat structure and bird community, Number of bird species and breeding pairs belonged to hole and canopy guild were increase as the increase of coverstory coverage and number of large trees. Therefore, it is necessary to make vertical structure more various to plant bushes, and to make DBH distribution more diverse for enhancing bird species diversity in the degraded ecosystem.

• Journal of Ecology and Environment
• /
• v.31 no.3
• /
• pp.207-211
• /
• 2008

We investigated the leaf demography of a temperate woody liana, Akebia trifoliata, in a temperate forest in Japan, Akebia is semi-evergreen: some leaves are shed before winter, while others remain through the winter. Previous studies of semi-evergreen species found that variation in leaf life span was caused by variation in the timing of leaf emergence, Leaves that appeared just before winter over-wintered, while leaves appearing earlier were shed, However, it is unclear whether leaves of the same cohort (i.e., leaves that appear at the same time within a single site) show variation in life span under the effect of strong seasonality. To separate variation in life span among the leaves in each cohort from variation among cohorts, we propose a new method - the single leaf diagram, which shows the emergence and death of each leaf. Using single leaf diagrams, our study revealed that Akebia leaves within a cohort showed substantial variation in life span, with some over-wintering and some not. In addition, leaves on small ramets in the understory showed great variation in life span, while leaves on large ramets, which typically reach higher positions in the forest canopy, have shorter lives, As a result, small ramets were semi-evergreen, whereas large ramets were deciduous, The longer lives of leaves on small ramets can be interpreted as a shade-adaptive strategy in understory plants.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.50 no.5
• /
• pp.301-308
• /
• 2005

This study was carried out to investigate the effect of stem-cutting (SC) length and portion on the major agronomic characters related with dry matter production and accumulation, and to examine their relation­ships in cassava. When cassava was planted with longer SCs or with older portion SCs, major canopy or source characters like leaf number and leaf area index developed excessively, while tuber yields could be reduced due to the decrease of root/shoot ratio, relative growth rate, root dry weight, and harvest index, particularly in the bitter varieties (high cyanide-level varieties). It was considered that the sweet varieties (low cyanide-level varieties) be early­bulked with higher tuber yield when they are planted with the 25-30 cm long SCs or with the SCs from young type to semi-mature portions of mother stems, while the bitter varieties with the 15-20 cm long SCs or with the SCs from semi-mature to hardwood portions of mother stems, respectively. However, a significant interaction between length and portion of SC was not observed in all agronomic characters.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.3 no.1
• /
• pp.91-98
• /
• 1993

This study was carried out to investigate characteristic of vinyl chloride emissioned from poly vinyl chloride extrusion process and to evaluate the efficiency of local exhaust ventilation system. Before local ventilation facility was constructed in poly vinyl chloride extrusion process, the average worker exposure to vinyl chloride was 3.15 ppm, which exceeded Threshold Limit Value of American Conference of Gorvernmental Industrial Hygienists (ACGIH-TLV), 1 ppm. lt is possible that vinyl chloride residues in the poly vinyl chloride resin was released or degased due to extrusion heat. The larger the width of vinyl tube become, the higher worker exposure to vinyl chloride was. It is estimated that vinyl chloride from vinyl chloride resin increased as amount of poly vinyl chloride resin extruded in the extrusion process increased. Canopy hood was an appropriate type for poly vinyl chloride resin extrusion process. This local exhaust ventilation has fan static pressure of 7.65 inch wg($190mmH_2O$, total volumetric flowlate of 4,796 CFM ($135.8m^3$/min) and fan power requirement of 12 hp (8.952 Kw). After this local exhaust ventilation was constructed there, the average concentration of worker exposure to vinyl chloride was reduced to be 0.46 ppm, which was below the Threshold Limit Value, 1 ppm. Also, the removal efficiency rate of vinyl chloride attained by local exhaust ventilation was 85.3%. It was a statistically significant (p<0.01).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.33 no.6
• /
• pp.547-555
• /
• 2015

The vegetation index is a crucial parameter in many biophysical studies of vegetation, and is also a valuable content in ecological processes researching. The OVIs (Optical Vegetation Index) that of using multispectral and hyperspectral data have been widely investigated in the literature, while the RVI (Radar Vegetation Index) that of considering volume scattering measurement has been paid relatively little attention. Also, there was only some efforts have been put to fuse the OVI with the RVI as an integrated vegetation index. To address this issue, this paper presents a novel FVI (Fusion Vegetation Index) that uses multispectral and full-PolSAR (Polarimetric Synthetic Aperture Radar) data. By fusing a NDVI (Normalized Difference Vegetation Index) of RapidEye and an RVI of C-band Radarsat-2, we demonstrated that the proposed FVI has higher separability in different vegetation types than only with OVI and RVI. Also, the experimental results show that the proposed index not only has information on the vegetation greenness of the NDVI, but also has information on the canopy structure of the RVI. Based on this preliminary result, since the vegetation monitoring is more detailed, it could be possible in various application fields; this synergistic FVI will be further developed in the future.

• Journal of Korean Society for Atmospheric Environment
• /
• v.28 no.2
• /
• pp.119-130
• /
• 2012

Heat island phenomena in Chuncheon (Korea) were investigated using air temperature measured by automatic weather stations and temperature dataloggers located at rural and urban sites. Numerical simulation of the phenomena was performed using Weather Research and Forecasting Urban Canopy Model (WRF-UCM) and results were compared with the observation. The model was initialized with NCEP/FNL data. The horizontal resolution of the fine domain is 0.33 km. The results of observational analyses show that the intensity of heat island was significantly higher during the nighttime than during the daytime. The highest measured temperature difference between rural and urban site is $3.49^{\circ}C$ and average temperature difference varies between 1.4 and $1.9^{\circ}C$. Good agreement was found between the simulated and observed temperatures. However, significantly overestimated wind speed was found at the urban sites. The linear regression analysis between observed and simulated temperature shows high correlation coefficient 0.96 for urban and 0.94 for rural sites while for wind speed, a very low correlation coefficient was found, 0.30 and 0.55 respectively.

• Journal of Environmental Science International
• /
• v.25 no.11
• /
• pp.1475-1484
• /
• 2016

To analyze the cooling effect of urban green areas, we conducted micrometeorological measurements in these areas and their surroundings in Seoul, Korea. From the average hourly temperature measurements through each month for the last two years (March 2013 to February 2015), we found that the maximum temperature difference between urban and green areas was about $2.9^{\circ}C$ at 16:00 LST in summer, and the minimum was about $1.7^{\circ}C$ at 22:00 LST in winter. In summer, the temperature difference was the largest during the day, rather than at night, due mainly to shading by the tree canopy. The specific humidity difference between the two areas was about $1.5g\;kg^{-1}$ in summer, and this decreased in the winter. The specific humidity difference between urban and green areas in summer is relatively large during the day, due to the higher evapotranspiration level of biologically active plants.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.21 no.1
• /
• pp.73-82
• /
• 2018

Urban parks are important bird habitat in cities. Various studies have evaluated the habitat function of urban parks focused on field surveys. In this study, we performed applicability of NDVI obtained from Landsat 8 OLI image as a factor for spatial planning considered bird diversity. This study was classified with green boundary into three groups using NDVI's value. Environmental variables were calculated by the green area ratio of the surrounding area from 100m to 500m at each groups. The 20 environmental variables such as park area, park shape index, canopy of tree, etc. were derived, the regression analysis was performed as a dependent variable for the bird diversity of urban parks. As a result, the park area and the green area ratio of Group 3, classified high NDVI, within the 100m buffer were adopted as the variables in the regression model. In other words, it was confirmed that as the park becomes larger, the distribution of key green areas within a radius of 100m of the parks becomes higher, the diversity of bird species has increased. It was appropriate to use satellite image, NDVI to analyze species diversity in urban area.