• Korean Journal of Agricultural Science
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• v.35 no.2
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• pp.119-126
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• 2008

This study was carried out to find the botanical characters and effect of weed control for herbicides treatment after barley sowing. Barley variety used in study was "Yuyeon", hood-type awn for whole crop forage use, which developed at RDA in 2004. Sowing date was on 10th October, 2007, and was drilled as $60{\times}20cm$. Herbicides were treated on 2th day after barley sowing. Measured items were number and kinds of weeds at each treatment and growth characteristics and grain yield in barley. Cerastium holosteoides var. hallaisanense among weeds surveyed at tillering stages in Butachlor treatment were highly appeared, but Alopecurus aequalis var. amurensis did not appeared while Alopecurus aequalis var. amurensis was 39 plants and Capeslla bursa-pastoris was 37 plants in check. Occurrence of the Capeslla bursa-pastoris at primary survey and Cerastium holosteoides var. hallaisanense in ripening stage were high, while Alopecurus aequalis var. amurensis did not emerged. Botanical characteristics of barley each as plant height, number of tillers and spiklets per plant. surveyed at ripening stage were higher than check. Grain yield per 10a was the highest at Alachlor among treatments, while dry matter of leaf and culm were similar among treatments. Therefore, effect of yield increasing of barley by herbicide after sowing was reconfirmed through this study. Especially, effect of Alachlor was lightly high compared with others.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.357-365
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• 2016

The effects of elevated atmospheric $CO_2$ on photosynthesis and growth of Chinese cabbage (Brassica campestris subsp. napus var. pekinensis) were investigated to predict productivity in highland cropping in an environment where $CO_2$ levels are increasing. Vegetative growth, based on fresh weight of the aerial part, and leaf characteristics (number, area, length, and width) of Chinese cabbage grown for 5 weeks, increased significantly under elevated $CO_2$ ($800{\mu}mol{\cdot}mol^{-1}$) compared to ambient $CO_2$ ($400{\mu}mol{\cdot}mol^{-1}$). The photosynthetic rate (A), stomatal conductance ($g_s$), and water use efficiency (WUE) increased, although the transpiration rate (E) decreased, under elevated atmospheric $CO_2$. The photosynthetic light-response parameters, the maximum photosynthetic rate ($A_{max}$) and apparent quantum yield (${\varphi}$), were higher at elevated $CO_2$ than at ambient $CO_2$, while the light compensation point ($Q_{comp}$) was lower at elevated $CO_2$. In particular, the maximum photosynthetic rate ($A_{max}$) was higher at elevated $CO_2$ by 2.2-fold than at ambient $CO_2$. However, the photosynthetic $CO_2$-response parameters such as light respiration rate ($R_p$), maximum Rubisco carboxylation efficiency ($V_{cmax}$), and $CO_2$ compensation point (CCP) were less responsive to elevated $CO_2$ relative to the light-response parameters. The photochemical efficiency parameters ($F_v/F_m$, $F_v/F_o$) of PSII were not significantly affected by elevated $CO_2$, suggesting that elevated atmospheric $CO_2$ will not reduce the photosynthetic efficiency of Chinese cabbage in highland cropping. The optimal temperature for photosynthesis shifted significantly by about $2^{\circ}C$ under elevated $CO_2$. Above the optimal temperature, the photosynthetic rate (A) decreased and the dark respiration rate ($R_d$) increased as the temperature increased. These findings indicate that future increases in $CO_2$ will favor the growth of Chinese cabbage on highland cropping, and its productivity will increase due to the increase in photosynthetic affinity for light rather than $CO_2$.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.177-188
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• 2019

The aim of our study was to identify the changing trends in the composition, structure, and spatial distribution of forest vegetation in Apsan Park, a representative urban forest in Daegu, South Korea. A vegetation survey was conducted in 1997 and 2016 using phytosociological methods, and a detailed vegetation map was created using the physiognomic dominant species. There were 22 vegetation types in both 1997 and 2016, but two of those types increased and two decreased. The total coverage per unit area ($100m^2$) of the component vegetation species increased from 163% in 1997 to 182% in 2016, and natural vegetation tended to be more than twice that of artificial vegetation. The average number of species decreased by seven from 25 in 1997 to 18 in 2016. Species diversity (H') increased only slightly from 1,654 in 1997 to 1,680 in 2016, while species dominance (D) decreased by 9% from 0.304 in 1997 to 0.276 in 2016. The similarity in the composition of the forest vegetation was about 78%, which was nearly the same. The life form spectrums of vascular plants changed from '$G-R_5-D_4-e$' in 1997 to '$MM-R_5-D_4-e$' in 2016 and the central dormancy type changed from geophytes (G) to megaphanerophytes (MM). The spatial distribution of the forest vegetation was reduced by approximately four times that of artificial vegetation. The number of forest landscape elements (patches) increased from 269 in 1997 to 294 in 2016, while the average area decreased by 12% from 5.8 ha in 1997 to 5.1 ha in 2016.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.933-948
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• 2023

Atmospheric aerosols not only have adverse effects on human health but also exert direct and indirect impacts on the climate system. Consequently, it is imperative to comprehend the characteristics and spatiotemporal distribution of aerosols. Numerous research endeavors have been undertaken to monitor aerosols, predominantly through the retrieval of aerosol optical depth (AOD) via satellite-based observations. Nonetheless, this approach primarily relies on a look-up table-based inversion algorithm, characterized by computationally intensive operations and associated uncertainties. In this study, a novel high-resolution AOD direct retrieval algorithm, leveraging machine learning, was developed using top-of-atmosphere reflectance data derived from the Geostationary Ocean Color Imager-II (GOCI-II), in conjunction with their differences from the past 30-day minimum reflectance, and meteorological variables from numerical models. The Light Gradient Boosting Machine (LGBM) technique was harnessed, and the resultant estimates underwent rigorous validation encompassing random, temporal, and spatial N-fold cross-validation (CV) using ground-based observation data from Aerosol Robotic Network (AERONET) AOD. The three CV results consistently demonstrated robust performance, yielding R²=0.70-0.80, RMSE=0.08-0.09, and within the expected error (EE) of 75.2-85.1%. The Shapley Additive exPlanations(SHAP) analysis confirmed the substantial influence of reflectance-related variables on AOD estimation. A comprehensive examination of the spatiotemporal distribution of AOD in Seoul and Ulsan revealed that the developed LGBM model yielded results that are in close concordance with AERONET AOD over time, thereby confirming its suitability for AOD retrieval at high spatiotemporal resolution (i.e., hourly, 250 m). Furthermore, upon comparing data coverage, it was ascertained that the LGBM model enhanced data retrieval frequency by approximately 8.8% in comparison to the GOCI-II L2 AOD products, ameliorating issues associated with excessive masking over very illuminated surfaces that are often encountered in physics-based AOD retrieval processes.

• Korean Journal of Heritage: History & Science
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• v.42 no.1
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• pp.122-142
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• 2009

This study explored all domestic and international theories for maintenance and health enhancement of an old and big tree, and carried out the anatomical survey of the operation part of the tree toward he current status of domestic surgery and the perception survey of an expert group, and drew out following conclusion through the process of suggesting its reform plan. First, as a result of analyzing the correlation of the 67 subject trees with their ages, growth status. surroundings, it revealed that they were closely related to positional characteristic, damage size, whereas were little related to materials by fillers. Second, the size of the affected part was the most frequent at the bough sheared part under $0.09m^2$, and the hollow size by position(part) was the biggest at 'root + stem' starting from the behind of the main root and stem As a result of analyzing the correlation, the same result was elicited at the group with low correlation. Third, the problem was serious in charging the fillers (especially urethane) in the big hollow or exposed root produced at the behind of the root and stem part, or surface-processing it. The benefit by charging the hollow part was analyzed as not so much. Fourth, the surface-processing of fillers currently used (artificial bark) is mainly 'epoxy+woven fabric+cork', but it is not flexible, so it has brought forth problems of frequent cracks and cracked surface at the joint part with the treetextured part. Fifth, the correlation with the external status of the operated part was very high with the closeness, surface condition, formation of adhesive tissue and internal survey result. Sixth, the most influential thing on flushing by the wrong management of an old and big tree was banking, and a wrong pruning was the source of the ground part damage. In pruning a small bough can easily recover itself from its damage as its formation of adhesive tissue when it is cut by a standard method. Seventh, the parameters affecting the times of related business handling of an old and big tree are 'the need of the conscious reform of the manager and related business'. Eighth, a reform plan in an institutional aspect can include the arrangement of the law and organization of the old and big tree management and preservation at an institutional aspect. This study for preparing a reform plan through the status survey of the designated old and big tree, has a limit inducing a reform plan based on the status survey through individual research, and a weak point suggesting grounds by any statistical data. This can be complemented by subsequent studies.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.152-165
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• 1993

This is the basic study in order to know the amount of transpirational water loss in a Larix leptorepis stand by a heat pulse method. Especially this study has been measured and discussed the diurnal and seasonal trends of heat pulse velocity by changes of radiation, temperature and humidity, differences of heat pulse velocity by direction and depth in stem, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal change of heat pulse velocity by change of leaf water potential, sap flow path way in sapwood by dye penetration and amount of daily and annual transpiration in a tree and stand. The results obtained as follows : 1. Relation between heat pulse velocity(V) and sap flow rate(SFR) was established as a equation of SFR=1.37V($r=0.96^{**}$). 2. The sap flow rate presented in the order of dominant, codominant and suppressed tree, respectively. The daily heat pulse velocity was changed by radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity in individual trees did not differ in early morning and in late night, but had some differed from 12 to 16 hours when radiation was relatively high. 4. The heat pulse velocity and leaf water potential showed similar diurnal variation. 5. The seasonal variation of heat pulse velocity was highest in August, but lowest in October and similar value of heat pulse velocity in the other months. 6. The heat pulse velocity in stem by direction was highest in eastern, but lowest in southern and similar velocity in western and northern. 7. The difference of heat pulse velocity in according to depths was highest in 2.0cm depth, medium in 1.0cm depth, and lowest in 3.0cm depth from surface of stem. 8. The sap flow path way in stem showed spiral ascent turning right pattern in five sample trees, especially showed little spiral ascent turning right in lower part than 3m hight above ground, but very speedy in higher than 3m hight. 9. The amount of sap flow(SF) was presented as a equation of SF=1.37AV and especially SF in dominant tree was larger than in codominant or suppressed tree. 10. The amount of daily transpiration was 30.8ton/ha/day and its composition ratio was 83% at day and 17% at night. 11. The amount of stand transpiration per month was largest in August(1,194ton/ha/month), lowest in May (386ton/ha/month). The amount of stand transpiration per year was 3,983ton/ha/year.