• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.5
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• pp.8-13
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• 2000

X-ray diffraction technique was used to quantify change of cellulose crystallinity during refining. XRD data confirmed that fiber wall delamination was caused by the structural conversion of celluloses which occurred in a liquid medium during refining. The quantified crystallinity of celluloses in pulp fibers was closely associated with the change of fiber wall delamination, which was defined by measurement of fiber wall thickness. In particular, it was well recognized that low intensity beating showed a better response in the change of crystallinity than high intensity one. The decrease o cellulose crystallinity during refining considerably enhanced the improvement of interfiber bonding ability of a dried sheet.

• Korean Journal of Remote Sensing
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• v.24 no.3
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• pp.267-272
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• 2008

Tree species-specific estimates with spacebome high-resolution imagery improve estimation of forest biomass which is needed to predict the long term planning for the sustainable forest management(SFM). This paper is a contribution to develop crown distinguishing coniferous species, Pinus densiflora and Pinus koraiensis, from QuickBird imagery. The proposed feature analysis derived from shape parameters and first and second-order statistical texture features of the same test area were compared for the two species separation and delineation. As expected, initial studies have shown that both formfactor and compactness shape parameters provided the successful differentiating method between the pine species within the compartment for single crown identification from spaceborne high resolution imagery. Another result revealed that the selected texture parameters - the mean, variance, angular second moment(ASM) - in the infrared band image could produce good subset combination of texture features for representing detailed tree crown outline.

• Journal of Forest and Environmental Science
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• v.27 no.1
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• pp.47-54
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• 2011

Allometry and basal area equations were developed with various tree measurement variables for the major species; Quercus variabilis, Quercus mongolica, Pinus koraiensis and Larix leptolepis in Korea. For allometry models, the relationships between total height-DBH, crown width-DBH, height to the widest portion of the crown-total height, and height to base of crown-total height were investigated. Multiple regression methods were used to relate annual basal area growth to tree variables of initial size (DBH, total height, and crown width), relative size (relative diameter and relative height) as well as competition measures (competition index, crown class, and live crown ratio).

• Korean Journal of Environment and Ecology
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• v.35 no.5
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• pp.569-575
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• 2021

This study analyzed the effect of forests on reducing particulate matter by investigating the particulate matter concentration and influencing factors between urban forest and traffic forest. The concentrations of particulate matter in Hongreung Experimental Forest (urban forest) and a forest (traffic forest) formed at the intersection of Cheongryangri Station in Dongdaemun-gu, Seoul were measured with the light scattering method instrument from January to November 2018. During the study period, the average PM₁₀ concentrations in the urban forest and the traffic forest were 12.5㎍/m³ and 15.7 ㎍/m³, respectively, and the average PM_2.5 concentrations were 16.6㎍/m³and 6.9 ㎍/m³, respectively. Comparing the concentration by the urban atmospheric measurement network of the Ministry of Environment and the concentration in urban forests showed that the reduction rate of PM₁₀ was 66.9±28.6% in urbanforest and 58.6±44.1% in traffic forest and that of PM_2.5 was 71.3±23.0% and 64.9±31.3%. The difference in the reduction rate of particulate matter is likely related to the size and structure of the urban forest, and the wind velocity is considered the reduction factor.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.437-445
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• 2013

This study was conducted to develop site index equations and to estimate productive areas of Quercus acutissima by ecoprovince in Korea using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 48 environmental factors including 19 climatic variables were regressed on site index to develop site index equations. Four to six environmental factors for Quercus acutissima by ecoprovince were selected as independent variables in the final site index equations. The result showed that the coefficients of determination for site index equations were ranged from 0.30 to 0.41, which seem to be relatively low but good enough for the estimation of forest stand productivity. The site index equations developed in this study were also verified by three evaluation statistics such as the estimation bias of model, precision of model, and mean square error of measurement. According to the evaluation statistics, it was found that the site index equations fitted well to the test data sets with relatively low bias and variation. As a result, it was concluded that the site index equations were well capable of estimating site quality. Based on the site index equations of Quercus acutissima by ecoprovince, the productive areas by ecoprovince were estimated by applying GIS technique to the digital forest site map and climate map. In addition, the distribution of productive areas by ecoprovince was illustrated by using GIS technique.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.79-89
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• 2016

In this paper, we proposed the object classification method using genetic and dynamic random forest consisting of optimal combination of unit tree. The random forest can ensure good generalization performance in combination of large amount of trees by assigning the randomization to the training samples and feature selection, etc. allocated to the decision tree as an ensemble classification model which combines with the unit decision tree based on the bagging. However, the random forest is composed of unit trees randomly, so it can show the excellent classification performance only when the sufficient amounts of trees are combined. There is no quantitative measurement method for the number of trees, and there is no choice but to repeat random tree structure continuously. The proposed algorithm is composed of random forest with a combination of optimal tree while maintaining the generalization performance of random forest. To achieve this, the problem of improving the classification performance was assigned to the optimization problem which found the optimal tree combination. For this end, the genetic algorithm methodology was applied. As a result of experiment, we had found out that the proposed algorithm could improve about 3~5% of classification performance in specific cases like common database and self infrared database compare with the existing random forest. In addition, we had shown that the optimal tree combination was decided at 55~60% level from the maximum trees.

• Journal of Forest and Environmental Science
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• v.28 no.4
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• pp.232-241
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• 2012

We investigated the relationship between vegetation type and soil carbon dynamics in even-aged alder (Alnus hirsuta) and Korean pine (Pinus koraiensis) plantations in central Korea. Both forests were located on the same soil parent material and occupied similar topographic positions. Soil $CO_2$ efflux in the two plantations was determined using a dynamic chamber method accompanied by measurements of soil moisture content and temperature. Mean soil temperature was similar in the two plantations, but mean soil water content was significantly higher in the alder plantation than in the pine plantation. In both plantations, seasonal patterns in soil $CO_2$ efflux exhibited pronounced variation that corresponded to soil temperature. Soil water content did not affect the seasonal variation in soil $CO_2$ efflux. However, in summer, when soil temperature was above $17^{\circ}C$, soil $CO_2$ efflux increased linearly with soil water content in the alder plantation. Estimated $Q_{10}$ was 3.3 for the alder plantation and 2.7 for the pine plantation. Mean soil respiration during the measurement period in the alder plantation was 0.43 g $CO_2\;m^{-2}\;h^{-1}$, which was 1.3 times higher than in the pine plantation (0.33 g $CO_2\;m^{-2}\;h^{-1}$). Higher soil $CO_2$ efflux in the alder plantation might be related to nitrogen availability, particularly the concentration of $NO_3{^-}$, which was measured using the ion-exchange resin bag method.

• Journal of Forest and Environmental Science
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• v.32 no.2
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• pp.196-204
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• 2016

In this study, vegetation succession and the rate of consequent topsoil development were investigated in shallow landslide scars of sedimentary rock slopes covered by volcanic ashes and pumice in Kagoshima prefecture, Japan. Seven shallow landslide scars of different ages were selected as study areas. In the initial period after the occurrence of a shallow landslide, deciduous broad-leaved trees such as Mallotus japonicus or Callicarpa mollis were occupied in the areas. Approximately 30 years after the landslide, evergreen broad-leaved trees such as Cinnamomum japonicum invaded in the areas, already existed present deciduous broad-leaved trees. After 50 years, the summit of the canopy comprised evergreen broad-leaved trees such as Castanopsis cuspidata var. sieboldii and Machilus thunbergii. Moreover, the diversity of vegetation invading the site reached the maximum after 15 years, followed by a decrease and stability in the number of trees. The total basal areas under vegetation increased with time. It was concluded that the vegetation community reaches the climax stage approximately 50 years after the occurrence of a shallow landslide in the study areas, in terms of the Fisher-Williams index of diversity (${\alpha}$) and the prevalence of evergreen broad-leaved trees. Moreover, according to the results of topsoil measurement in the study areas, the topsoil was formed at the rate of 0.31 cm/year. The development of topsoil usually functions to improve the multi-faceted functions of a forest. However, when the increased depth of topsoil exceeds the stability threshold, the conditions for a shallow landslide occurrence are satisfied. Therefore, we indicated to control the depth of topsoil and strengthen its resistance by forest management in order to restrain the occurrence of shallow landslides.

• Journal of the Korean Wood Science and Technology
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• v.35 no.3
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• pp.79-87
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• 2007

This study investigated the effects of lacquer-finishing to prevent discoloration of coloring chestnut wood coated with natural dyes from deteriorating factors such as lights (indoor, 500 lux and outdoor, 50,000~70,000 lux), acid, alkali, and heat through measurement of color difference. Lacquer-finishing coating contributed to protection of intrinsic color of the natural dyeing woods in spite of severe treatment. In particular, dyeing liquor with alkali pH played a great role in prevention of light discoloration.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.164-172
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• 2013

The purpose of this research was development of quantitative ultrasonic test methodology for detecting internal defects in members of ancient wooden building. Connection part between wooden members and/or contacted or hidden part by wall of ceiling or other construction materials make it hard to apply direct way of ultrasonic test. So indirect way of ultrasonic test needed to be applied. Test methodology with newly developed prototype of ultrasonic system was proposed. Homogeneous material with polypropylene was also tested for establishing the criterion. Results showed that TOF(time of flight)-energy and pulse length were found out to be proper ultrasonic parameters for predicting depth of defect in wood different from polypropylene. It was not possible to directly apply prediction equation derived from polypropylene. Newly established prediction equation shows coefficient of determination of 0.73 for wood. Finally, defect of replaced rafter members was predicted with the coefficient of determination of 0.32. Various aspects of ultrasound propagation in wood including anisotropy need to be carefully considered to raise up the prediction accuracy.