• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.93-104
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• 2000

The ecological characteristics of 10 natural stands of Dendropanax morbifera(Haenam, Wando 1, Wando 2, Bogildo, Kemundo and Hongdo and Sendol, Suoak, Hannam, and Kidowon populations in Cheju island) were studied. In most of the Dendropanax morbifera natural stands, the following tree species appeared predominantly : Camellia japonica, Castanopsis cuspidate var. sieboldii, Castanopsis cuspidate var. thunbergii, Carpinus laxiflora, Quercus acute and Eurya japonica. Especially, Camellia japonica and Eurya japonica appeared in all the stands. Dendropanax morbifera occupied 17.2% of the upper story, 12.9% of the middle story, and 10.3% of the lower story, respectively. The distribution patterns by Morisita's Index showed that Dendropanax morbifera was distributed randomly in all of the three stories, i.e. the upper, the middle and the lower stories. Dendropanax morbifera was positively associated with Camellia japonica, Eurya japonica, Carpinus laxiflora, Cinnamomum japonicum, Ligustrum japonicum, Callicarpa Japonica, Castanopsis cuspidate var. thunbergii, Castanopsis cuspidata var. sieboldii, Daphniphyllum macropodum, Acer palmatum and Euonymus oxyphyllus. This might suggest that the ecological niche is similar to each other. The cluster analysis using percent dissimilarity(PD) based on species composition divided into two groups. One group consisted of the populations located along the south-western coasts. The other group consisted of the populations of Cheju island. This result was agree with that of ordination analysis. From these results, We could find out that the species composition of the populations of Dendrapanax morbifera in Cheju island was quite different from those of other regions.

• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.316-324
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• 1996

This study was conducted by relative time study to identify the allowance time and basic work time, which is together composed of the total work time, in the wage composition and work process composition. This study was done for the case of a basic one person a group from thinning treatment for some conifer species such as Japanese red pine, Japanese larch, pitch pine and Korean pine. 1. In order to apply the Japanese allowance time of four species to the general conifer case, the maximum value of allowance time composition value among those of four species was selected. The results are as follows: delay time for person 1.8%, rest time 14.1%, delay time for machine 12.5% and wating time 0.4%. The some of ratios of adjustment allowance time is 28.8%. 2. Estimated wage basis time table, which can be used for wage table or process table, was prepared by adding up adjusted general allowance time and standard work time estimated by estimation equation for each species through the time study.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.185-197
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• 2000

This study was carried out to research structure of forest vegetation and site condition, and supply basic data for conservation of pine forest and ecologically sustainable forest management and control in Anmyondo area. The forest of Anmyondo were largely classified as four forest community : Pinus densiflora community, Pinus thunbergii community, Pinus rigida community, and Quercus variabilis community. Organic matter, total nitrogen, and other nutrients in soil of the study area were relatively low, and average soil pH was 4.9. Soil texture was sandy clay or heavy clay and so the aeration and permeability could be poor. In this study site, the methods such as the promotion of germination of pine seeds through removal of forest floor and inducement of natural regeneration through such method as regeneration under shelter wood would be better than the method such as afforestation after clear-cutting for conservation the pine forests. Also, it will be a good method to practice tending for hardwood species in the dominant areas by hardwood species.

• Korean Journal of Environment and Ecology
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• v.12 no.1
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• pp.30-41
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• 1998

This study analyzed urban greenspace area and vegetation structure by land use types for Kangnam-gu and Junglang-gu in Seoul different in income and building construction date. The study districts had a similar areal distribution of land use types. Residential lands accounted for about 32~37% of total area, natural lands, 19~22%, commercial and industrial lands(including transportation), 13~18%, and institutional lands, 13~17%. Greenspace covered only 20~30% of urban residential and commercial area in which human activities of living concentrate. Canopy stocking level in urban lands (all land uses except natural and agrecultural lands) was about 39% for Kangnam-gu and 50% for Junglang-gu, showing tree planting potential slightly higher in Kangnam-gu than in Junglang-gu. Woody plant cover was approximately 13%, and tree density was 3 trees/100m$^{2}$ forurban lands in both districts. The tree-age structure was largely characterized by young, growing tree population, and species diversity within a diameter class decreases as the diameter classes get larger. Urban lands of both districts had quite a similar species composition of woody plants (similarity indez of 0.70). Income and bulding construction date did not result in significant diference between the two districts in vegetation structure for urban lands. Some strategies were ezplored to solve problems found in the present greenspace structures. They included increase of biomass and greenspace area through minimization of unnecessary impervious surfaces, creation of multilayered and multiaged vegetation structures, and avoidance of intensive tree pruning and relocation of above ground utility lines.

• Korean Journal of Environment and Ecology
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• v.3 no.1
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• pp.42-50
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• 1989

A valley and a ridge forest in Mt. Gaya area was studied to investigate forest structure in relation to altitude and part of slope. Sixty-three quadrats were set up in the valley forest along altitude of 600m to 1,000m and part of slope, and thirty-eight quadrats were set up in the ridge forest along altitude of 700m to 1,430m. According to the importance values, the valley forest was Quercus mongolica-Lespedeza maximowiczii community and the ridge forest was Pinus densiflora, Quercus mongolica-Rhododendron mucronulatum community. Similarity index between the valley forest community and the ridge forest community was 37.2%. Shannon's species diversities of the valley forest community and the ridge forest community were 1.3402 and 1.0098, respectively. According to importance values by crown stories and DCA ordination, successional trends of tree species may be from Pinus densiflora and Pinus koraiensis through Quercus mongolica to Quercus serrata and Carpinus laxiflora. As going from the lower part to upper part of the slope in the valley forest, the importance values of Quercus mongolica, Quercus aliena, Rhododendron mucronulatum and Lespedeza maximowiczii increased while those of Carpinus laxiflora and Fraxinus rhynchophylla decreased. With increasing elevation in the valley and ridge forest, the importance value of Pinus densiflora decreased while that of Quercus mongolica increased. In the valley forest, densities of canopy and shrubstratum increased as increasing elevation, and the number of species and species diversity decreased as increasing elevation and going from the lower part to the upper of slope. The range of similarity indices between parts of the slope, and the elevation belts of 100m in the valley forest were 66.6-69.2 and 25.9-79.8%, respectively. In the ridge forest, density and basal area of canopy tended to decreased as increasing elevation, and the range of similarity indices between elevation belts of 100m was 27.9-98.2%.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.36-42
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• 2001

Changes in breeding bird community and forest structure by thinning were investigated from April 1997 to August 1998 in 10ha ($400{\times}250m$) of temperate mixed hardwood forest in Mt. Gariwang which is located in National Forest, Pyoungchang, Kangwon Province, Korea. Bird community was surveyed by the territory mapping method and forest structure was done by analyzing the vertical structure of foliage, distribution of diameter at breast height (DBH) of trees and tree species composition. After the thinning, tree density, number of tree species and basal area were decreased from 195ea/ha, 18 species and 6.69 $m^2/ha$ into 100ea/ha, 13 species and 3.04 $m^2/ha$, respectively. Foliage coverages in upper and mid layer were decreased, but coverage in low layer was increased. Large trees (Over 40cm of DBH) were decreased. Number of breeding bird species and pairs were decreased from 14 species and 23 pairs into 8 species and 12 pairs after the thinning. Number of breeding pairs of Yellow-breasted bunting Emberiza elegans incresed. There were decrease in number of species in hole & bush-nesting and canopy & bush-foraging guild. The results suggested that the thinning affect the species composition of breeding bird community and the forest structure. Changes of habitat structure might influence in breeding bird's density, species diversity and habitat using pattern of breeding bird community.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.229-238
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• 2019

Various wood defects occur during tree growing or wood processing. Thus, to use wood practically, it is necessary to objectively assess their quality based on the usage requirement by accurately classifying their defects. However, manual visual grading and species classification may result in differences due to subjective decisions; therefore, computer-vision-based image analysis is required for the objective evaluation of wood quality and the speeding up of wood production. In this study, the SIFT+k-NN and CNN models were used to implement a model that automatically classifies knots and analyze its accuracy. Toward this end, a total of 1,172 knot images in various shapes from five domestic conifers were used for learning and validation. For the SIFT+k-NN model, SIFT technology was used to extract properties from the knot images and k-NN was used for the classification, resulting in the classification with an accuracy of up to 60.53% when k-index was 17. The CNN model comprised 8 convolution layers and 3 hidden layers, and its maximum accuracy was 88.09% after 1205 epoch, which was higher than that of the SIFT+k-NN model. Moreover, if there is a large difference in the number of images by knot types, the SIFT+k-NN tended to show a learning biased toward the knot type with a higher number of images, whereas the CNN model did not show a drastic bias regardless of the difference in the number of images. Therefore, the CNN model showed better performance in knot classification. It is determined that the wood knot classification by the CNN model will show a sufficient accuracy in its practical applicability.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.402-411
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• 2018

This study was conducted to develop ingrowth estimation equations on Pinus densiflora found in Gangwon Province and in the center of Korean Peninsula, based on the National Forest Inventory (NFI)'s permanent sampling plot data. For this study, identical sampling plots in $5^{th}$ and $6^{th}$ NFI data were collected in order to identify ingrowth amounts for the last 5 years. Following two-stage approaches in developing the ingrowth estimation equations, the logistic regression model was used in the first stage to estimate the ingrowth probability. In the second stage, regression analysis on sampling plots with ingrowth occurrence was used to estimate the ingrowth amount. A candidate model was finally selected as an optimal model after a verification based on three evaluation statistics which include mean difference (MD), standard deviation of difference (SDD) and standard error of difference (SED). In results, a logistic regression model based on the number of sampling plot which did not result in ingrowth (model VI), was selected for an ingrowth probability estimation equation and exponential function including the species composition (SC) variable was optimal for an ingrowth estimation equation (model VII). The ingrowth estimation equations developed in this study also evaluated the estimation ability in various forest stand conditions, and no particular issue in fitness or applicability was observed.

• Journal of Apiculture
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• v.34 no.3
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• pp.189-195
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• 2019

Plants release a large variety of volatile organic compounds (VOCs) into the surrounding atmosphere. Floral volatile compounds (FVCs) emitted from many plants is the critical factors for pollinator attraction and defense for adaptation in environments. Recent studies indicate that the chemical components contributing to FVCs play an important role in the honeybee attractiveness to flowers. Olfactory signals are rapidly learned, indicating that foraging behavior results from the association of plant chemicals acting as chemosensory cues for the bees. Solid phase microextraction(SPME)-GC/MS method was applied to analyze the chemical composition of FVCs according to the different species of Robinia spp. The abundant compounds identified in R. pseudoacacia were (Z)-β-ocimene (34.86%) and linalool (35.47%). Those of the tetraploid R. pseudoacacia were (Z)-β-ocimene (35.42%) and α-Farnesene (33.94%). The volatiles of R. margarettae 'Pink Cascade' comprised an abundance of (Z)-β-ocimene (42.73%), (E)-4,8-Dimethylnona-1,3,7-triene (37.23%). Differences in FVCs of the different species of Robinia spp. are discussed in light of biochemical constraints on volatile chemical synthesis and of the role of flower scent in ecology of pollination.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.791-806
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• 2020

In this study, a block shear strength test was conducted to compare and analyze the strength and failure mode on the glued laminated timber, CLT, and Ply-lam CLT, which are mainly used for the construction of wood construction as engineering wood. Through this, the Ply-lam CLT manufacturing conditions for optimum production, such as the type of lamina, plywood, adhesive, and layer composition, were investigated. The results are as follow. Through block shear strength test, it showed high strength in the order of glued laminated timber, Ply-lam CLT and CLT. In particular, the shear strength of Ply-lam CLT, which is made of a composite structure of larch plywood and larch lamina, passed 7.1 N/㎟, which is a Korean industrial standards for block shear strength of structural glued laminated timber. In addition, in this study, there was no different in shear strength according to the adhesive type used for glulam, CLT, and Ply-lam CLT adhesion. However, in the case of Ply-lam CLT, the difference in shear strength of Ply-lam CLT was shown according to the type of lamina and plywood. The results showed high strength in the order of Larix kaempferi > Mixed light hardwood ≒ Pinus densiflora, sieb, et, Zucc plywood. The optimal configuration of Ply-lam CLT is when larch plywood and larch lamina are used, and it is decided that the adhesive can be used by selecting PRF and PUR according to the application. The results of block shear strength failure mode by type of wood based materials were analyzed. The failure mode showed shear parallel-to-grain for glulam, rolling shear for CLT, and shear parallel-to-grain and rolling for ply-lam CLT. This is closely related to shear strength results and is decided to indicate higher shear strength in Ply-lam CLT than in CLT due to rolling shear.