• Korean Journal of Environment and Ecology
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• v.6 no.2
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• pp.147-153
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• 1993

The Dalbatjae-Birobong ridge forest in Mt. Sobaek area was studied to investigate forest community structure. Twenty 20m $\times$ 25m plots were set up in the studied ridge forest along altitude of 770m to 1,410m and vegetation analysis for tree stratum of the trees above 1cm DBH was carried out. The leading dominant tree species were Pinus densiflora in the lower elevation and Quercus mongolica in the higher elevation. According to importance value and cluster analysis, the studied ridge forest was classified into four forest communities of Pinus densiflora community, Pinus densiflora-Quercus mongolica community. Quercus mongolica community and Quercus mongolica-deciduous tree species community. According to importance value of major tree species in canopy and understory, the present community type seems to continue for a relatively long time. Species diversity of Pinus densiflora community, Pinus densiflora-Quercus mongolica community, Quercus mongolica community and Quercus mongolica-deciduous tree species community were 0.6791, 0.6850, 0.5296 and 0.7136, respectively.

• Korean Journal of Environment and Ecology
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• v.19 no.3
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• pp.258-268
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• 2005

The objective of this study was to monitor the edge vegetation development process after timber harvesting at deciduous hardwood forest in Seoul National University Research Forest of Baekwoonsan (Mt), Korea The results from the 4th (2001) and 5th (2003) survey for edge vegetation development process after timber harvesting are summarized as follows. The competitive species at the harvested forest edge are Lindera erythrocarpa, Weigela subsessilis, Lespedeza maximowiczii, Lindera obtusiioba, Arajia eiata. There were Lindera erythrocarpa, Ivelgela subsessilis, Staphyiea bumaida as competitive species at harvested forest border between harvested forest edge and harvested interior. And at the forest interior, the competitive species were Lindera erythrocarpa, Lindera obtusiloba. There were differences in the competitive species at the forest edge due to the differences in direction, altitude, and existing dominant species. But Lindera erythrocarpa, Weigela subsessilis were appeared to be a competitive specieg at the southwestern slope (A site) and northeastern slope (B site). After timber harvesting, Sasa borealisshowed a good growth in early days, but showed a tendency of declining with the developing of canopy layer And coverage was generally higher at the Northeastern slope (Site B) than southwestern slop (Site A). The similarity index was lower as the distance from the forest edge becomes farther.

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.506-512
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• 1996

Community structure and soil properties of larch forest which are used for breeding site by herons were studied at Apgogri, Hoengsung, Kangwon Province. This site has been protected as a Natural Monument(No. 248) from 1973, in Korea. Herons have used this habitat from February to October every year. In 1995, more than 700 herons were observed in this habitat. Most of the larches died due to group breeding of herons, and no larch saplings were found at forest floor. Nutrient contents of soil in this habitat were much higher than those in control plot(non-breeding site). This must be due to the addition of faeces from herons and of thin twigs and other organic materials from the canopy and bird nests. Species composition of herb layer in this habitat was quite different from that in control plot. Breeding site was dominated by Humulus japonicus, Persicaria fauriei, Persicaria perfoliata, Commelina communis, Chelidonium majus var. asiaticum, Digitaria sanguinalis, Bidens bipinnata. Dioscorea batatas which are indicator species of soil eutrophication. Similarity index of shrub and herb layer between the breeding site and control site was 0.36 and 0.07, respectively.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.4
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• pp.67-74
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• 2016

Drone images with high spatial resolution are emerging as an alternative to previous studies with extraction limits in high density forests. Individual tree in the dense forests were extracted from drone images. To detect the individual tree extracted through the image segmentation process, the image segmentation results were compared between the combination of DSM and all R,G,B band and the combination of DSM and R,G,B band separately. The changes in the tree density of a deciduous forest was experimented by time and image. Especially the image of May when the forests are dense, among the images of March, April, May, the individual tree extraction rate based on the trees surveyed on the site was 50%. The analysis results of the width of crown showed that the RMSE was less than 1.5m, which was the best result. For extraction of the experimental area, the two sizes of medium and small trees were extracted, and the extraction accuracy of the small trees was higher. The forest tree volume and forest biomass could be estimated if the tree height is extracted based on the above data and the DBH(diameter at breast height) is estimated using the relational expression between crown width and DBH.

• Korean Journal of Plant Resources
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• v.30 no.2
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• pp.176-190
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• 2017

South Korea is the northernmost distributional territory on the Camellietea japonicae (evergreen broad-leaved forests of the warm-temperate zone) in East Asia. A total of 40 stands were collected in terms of an ecologically-naturalized wild tea population (WTP), and their species composition was analyzed by $Z{\ddot{u}}rich$-Montpellier School's method with preliminary regard to forest canopy idendtification. Stand types were characterized by ecological flora's criteria such as Raunkiaer's life-form, neophyte, zonal distribution, and nativeness of species. Expansion of WTP distribution into the interior of the peninsula was recognized, than expected. The highest and northernmost WTPs have been recorded at Mt. Palgong, Daegu (390 m a.s.l.) and Iksan Jeonbuk (latitude $36^{\circ}$ 03' 33''), respectively. Altitudinal and latitudinal WTP distribution of Korea under continental climate shows lower than Japanese situation under oceanic climate. Community structure generally involved a few human interferences. Syngeographically WTP distribution was limited on the warm-temperate zone and the southernmost cool-temperate southern submontane zone. First driving force on distributional expansion of the WTP was anthropogenic, particularly in the northernmost distribution area. We finally confirmed an actual existence of the WTP in South Korea and suggested a long-term monitoring on the WTPs in national view of in-situ genetic resources with higher frost-resistance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.665-676
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• 2011

In this study, the nucleate pool boiling heat transfer coefficients (HTCs) and critical heat flux (CHF) for a smooth and square flat heater in a pool of pure water with and without carbon nanotubes (CNTs) dispersed at $60^{\circ}C$ were measured. Tested aqueous nanofluids were prepared using CNTs with volume concentrations of 0.0001%, 0.001%, and 0.01%. The CNTs were dispersed by chemically treating them with an acid in the absence of any polymers. The results showed that the pool boiling HTCs of the nanofluids are higher than those of pure water in the entire nucleate boiling regime. The acid-treated CNTs led to the deposition of a small amount of CNTs on the surface, and the CNTs themselves acted as heat-transfer-enhancing particles, owing to their very high thermal conductivity. There was a significant increase in the CHF- up to 150%-when compared to that of pure water containing CNTs with a volume concentration of 0.001%. This is attributed to the change in surface characteristics due to the deposition of a very thin layer of CNTs on the surface. This layer delays nucleate boiling and causes a reduction in the size of the large vapor canopy around the CHF. This results in a significant increase in the CHF.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.238-246
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• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if variable rate treatment (VRT) of N fertilizer, that was prescribed for site-specific management at panicle initiation stage, could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, 33kg N/ha at PIS) method. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model· equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for the calculation of the required N were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with an average of 57kg/ha that was higher than 33 kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%$ and $7.1\%$ in VRT from $14.6\%$ and $13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. In conclusion the procedure used in this paper was believed to be reliable and promising method for reducing within-field spatial variability of rice yield and protein content. However, inexpensive, reliable, and fast estimation methods of natural N supply and plant growth and nutrition status should be prepared before this method could be practically used for site-specific crop management in large-scale rice field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.2
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• pp.150-156
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• 2001

To explore the feasibility of recycled paper mulching in spring-grown potato the changes of soil environments and the growth and yield of potato under non-mulched control and three mulching treatments of recycled paper (RPM), transparent polyethylene film (TPFM), and black polyethylene film (BPFM) were examined over two spring seasons in 1998 and 1999 at Suwon, Korea. The mulching materials were a recycled mulch paper with 110 g/$m^2$ and a thickness of 0.1mm, which was manufactured from old corrugated containers for this experiment and the commercial polyethylene films with a thickness of 0.01mm. RPM lowered the average soil temperature at 5-cm depth during the potato growing period by 03$^{\circ}C$ compared with the control, whereas TPFM and BPFM raised it by 2.$0^{\circ}C$, and 1.8$^{\circ}C$, respectively. On a sunny day during sprout emergence, RPM reduced the maximum soil temperature by about 5$^{\circ}C$, while TPFM and BPFM enhanced it by about 11$^{\circ}C$ and 6.$0^{\circ}C$, respectively. The temperature difference between the control and the mulching treatments decreased with the development of canopy. All the mulching treatments had an advantage in preserving the soil moisture over the control. RPM and BPFM resulted in the effective control of weed by obstructing light transmission onto soil surface, but TPFM had no control effect of weed. Sprout emergence started two to three days earlier in TPFM and BPFM, but one day later in RPM than in the control due to the altered soil temperature by the mulching treatments. However, the final percentage of emergence was notably lower in TPFM than that in the control because of too high soil temperature during daytime, but was not different among the control, RPM, and BPFM. During the early stage of potato growth, the shoot and root growth under RPM was lower compared with the control, but afterwards, RPM outpaced the control. In 1998 experiment, the tuber yield under RPM and BPFM were significantly higher than those of the control and TPFM. In 1999 experiment, there was no significant difference in tuber yield between RPM and the control.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.45-50
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• 2005

This study was conducted to measure and understand the exchange of CO₂ and water in a rice canopy. Eddy covariance system was installed on a 10m tower along with other meteorological instruments. CO₂ flux and surface energy balance were measured throughout the whole growing season in 2003 over a typical paddy field in Icheon, Korea. During the early growth stage in May and June, most of net radiation was partitioned to latent heat flux with daytime Bowen ratio of 0.3 to 0.7. Evapotranspiration (i.e., daily integrated latent heat flux) typically ranged from 3 to 4 mm d/sup -1/, with even higher rates on sunny days. Daily integrated net ecosystem exchange (NEE) of CO₂ increased with increasing solar radiation and leaf area index (LAI). The NEE was especially high during the stages of young panicle formation and heading. On 1 June 2003, when the rice field was flooded, it was a weak sink of atmospheric CO₂ with an uptake rate of 9.1 gm/sup -2/d/sup -1/. Despite frequent rainy and cloudy conditions in summer, maximum NEE of 36.2 gm/sup -2/d/sup -1/ occurred on 31 July prior to heading stage. As rice crop senesced after early September, the NEE decreased.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.2
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• pp.21-35
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• 2020

Vegetation information is a very important factor used in various fields such as urban planning, landscaping, water resources, and the environment. Vegetation varies according to canopy density or chlorophyll content, but vegetation vitality is not considered when classifying vegetation areas in previous studies. In this study, in order to satisfy various applied studies, a study was conducted to set a threshold value of vegetation index considering vegetation vitality. First, an eBee fixed-wing drone was equipped with a multi-spectral camera to construct optical and near-infrared orthomosaic images. Then, GIS calculation was performed for each orthomosaic image to calculate the NDVI, GNDVI, SAVI, and MSAVI vegetation index. In addition, the vegetation position of the target site was investigated through VRS survey, and the accuracy of each vegetation index was evaluated using vegetation vitality. As a result, the scenario in which the vegetation vitality point was selected as the vegetation area was higher in the classification accuracy of the vegetation index than the scenario in which the vegetation vitality point was slightly insufficient. In addition, the Kappa coefficient for each vegetation index calculated by overlapping with each site survey point was used to select the best threshold value of vegetation index for classifying vegetation by scenario. Therefore, the evaluation of vegetation index accuracy considering the vegetation vitality suggested in this study is expected to provide useful information for decision-making support in various business fields such as city planning in the future.