• Journal of agriculture & life science
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• v.45 no.5
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• pp.25-31
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• 2011

This study was conducted to develop the growth model for diameter at breast height (DBH) and basal area (BA) of Larix leptolepis stands grown in eastern mountain areas, Jeollabuk-do and to enhance the precision of the models by adding regional and climatal factors, such as altitude, mean annual rainfall, and mean annual temperature. In results, it was analyzed that Schumacher polymorphic equation might be the best model to estimate DBH and BA growth. In case of the DBH growth model, precision was improved by adding altitude and mean annual rainfall. Moreover, in case of the BA growth model, precision was improved by adding mean annual rainfall. Meanwhile, it would be necessary for more precise model to add various factors, such as stand density, mortality, thinning ratio, and edaphic status along with regional and climatal factors.

• Journal of the Korean Institute of Landscape Architecture
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• v.21 no.2
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• pp.107-119
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• 1993

This study was conducted to increase to increase the plant species diversity, which was based on the analysis of plant community structure and the survey of human's disturbance degree in Mt. Yongma and Mt. Acha urban nature park, Seoul. The plant community were divided into four groups by TWINSPAN and DCA. These groups were Pinus rigida-P. densiflora community, Quercus mongolica-Q.aliena-Q.accutissima community, Robinia pseudoacaia-Q.accutissima-Poplus${\times}$albaglandulosa community and R.pseudoacacia community. The successional trends of tree species seems to be from P.densiflora, P.rigida, Sorbus alniflora to Q.mongolica, Q.aliena and from P.${\times}$albaglandulosa, R.pseudoacacia, through Q.accutissima, to Q. mongolica, Q.aliena. The species diversity of plant community was high in natual plant community but was low in artificial planting community respectively. Number of species, number of species individuals, indices of species diversity was lowered and soil hardness was increased by the user's trampling, undercutting work and planting P.koraiensis after thinning. In the basis of study results, we proposed the management plan for the urban forest.

• Journal of the Korea Furniture Society
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• v.24 no.1
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• pp.79-87
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• 2013

The objective of this study was to increase the utilizability of domestic thinning and small diameter wood as applying in pattern design which can be applied in interior decoration, wood craft and wood furniture, and in developing the designs of furniture and household items. Then we investigated the physical and mechanical characteristics of Acer mono wood by pressurization and heat treatment. Color change is clear, and the wood density is increased with increasing pressing rate. The compressive and bending strengths are decreased as heating time is increased after pressing. However, shrinkage is improved after pressing and heating.

• Journal of the Korea Furniture Society
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• v.25 no.2
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• pp.96-103
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• 2014

The objective of this study was to increase the utilizability of domestic thinning and small diameter wood as applying in pattern design which can be used in interior decoration, wood craft and wood furniture, and in developing the designs of furniture and household items. We investigated the physical and mechanical characteristics of Betula platyphylla Wood by pressurization and heat treatment. Color change is clear, and the wood density is increased with increasing pressing rate. The compressive strength, modulus of rupture and modulus of elasticity in bending strength are decreased as heating time is increased after pressing. However, shrinkage is improved after pressing and heating.

• Journal of Korean Society of Forest Science
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• v.104 no.2
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• pp.179-186
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• 2015

This study was conducted to understand the characteristics of flowering and the factors affecting fruiting grades of Acer pictum subsp. mono(APSM), We examined the characteristics of flowering and fruiting in various natural APSM forest, and investigated annual fruiting grade, DBH, tree height, number of APSM trees within 30 m on 29 selected trees in the natural broadleaved forest in Mt. Jungwang in Gangwon-do, from 2009 to 2014. APSM has heterodichogamous sexual system consist of protoandry and protogyny. Eight trees have changed their sex morphs; 3 trees change the sex morph PA to PG, and 5 trees does the sex morph PG to PA. Early fall of young ovary is concentrated until early July. Initially, the small samaras are common, and was gradually increased the samaras suffered insect damage. Most flowers of APSM are pollinated by Andrenidae sp., Syrphidae sp. and Tachinidae sp.. Number of early fall samaras and the status of fallen samaras showed a significant difference by the year and region. Corymbose panicle and young leaves developed on the top of APSM twigs. Newly grown opposite twigs of APSM did not grow sufficiently and had no floral buds. The highest fruiting grade of tree was 9.0, and the mean values was only 3.8. The highest fruiting grade of year was 4.55 in 2013, and the lowest did 0.07 in 2014. Highly significantly correlated and regressed between mean of annual fruiting rates and rates of crown under sun light. This results would imply that thinning for tree growth through improved light absorption might be a method to enhance seed production of APSM in the seed production forest.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.312-322
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• 2010

In Korea, Torreya nucifera (L.) Siebold & Zuccarini is widely distributed in the warm temperate zone of South coastal area and Jeju island, mainly as preserved forest in the vicinity of the Buddhist temple and Confucian temple. The objective of this study is in order to develop the conservation method and comprehension of vegetation community by current vegetation structure analysis of Torreya nucifera stand. As the results, the number of surveyed species in Torreya nucifera stand were total 148 species with 28 species of tree layer, 38 species of subtree layer, and 82 species of shrub layer. The appearance of the common species were Ligustrum obtusifolium Siebold & Zucc., Hedera rhombea Bean, and Trachelospermum asiaticum Nakai var. asiaticum. All the story of the surveyed region, Torreya nucifera maintained the current dominant species, but the subtree layer and shrub layer was decreased dominant rate because of the development of the crown of tree layer and biased growth of the subtree layer. Most of the tree layer and subtree layer in Torreya nucifera stands are composed of the sprout forest. Therefore, these results suggest that in order to maintain the healthy stand it is demanded for the application of selection thinning method for reducing crown competition in Torreya nucifera forests.

• Journal of Ecology and Environment
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• v.41 no.1
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• pp.1-8
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• 2017

Background: Though the biomass of floral vegetation in understory plant communities in a forested ecosystem only accounts for less than 1% of the total biomass of a forest, they contain most of the floral resources of a forest. The diversity of understory honey plants determines visitation rate of pollinators such as honey bee (Apis mellifera) as they provide rich food resources. Since the flower visitation and foraging activity of pollinators lead to the provision of pollination service, it also means the enhancement of plant-pollinator relationship. Therefore, an appropriate management scheme for understory vegetation is essential in order to conserve pollinator population that is decreasing due to habitat destruction and disease infection. This research examined the diversity of understory honey plant and studied how it is related to environmental variables such as (1) canopy density, (2) horizontal heterogeneity of canopy surface height, (3) slope gradient, and (4) distance from roads. Vegetation survey data of 39 plots of mixed forests in Chuncheon, Korea, were used, and possible management practices for understory vegetation were suggested. Results: This study found that 113 species among 141 species of honey plant of the forests were classified as understory vegetation. Also, the understory honey plant diversity is significantly positively correlated with distance from the nearest road and horizontal heterogeneity of canopy surface height and negatively correlated with canopy density. Conclusions: The diversity of understory honey plant vegetation is correlated to vegetation structure and human impact. In order to enhance the diversity of understory honey plant, management of density and height of canopy is necessary. This study suggests that improved diversity of canopy cover through thinning of overstory vegetation can increase the diversity of understory honey plant species.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.152-158
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• 2007

Micromorphological and chemical characteristics of living Castanea spp. and Tamarix spp. attacked by a brown-rot fungus were examined. Micromorphological features of brown-rotted hardwood species were similar to those observed in softwoods such as losses in birefringence under polarized microscopy, preferential degradation of $S_2$ layer and cracks in the $S_3$ layer. Thinning of the secondary cell wall in fibers was also observed, although it did not seem to be the main symptom. FT-IR analysis showed that bands assigned to cellulose and hemicelluloses decreased or disappeared, whereas the bands assigned to lignin increased. X-ray diffraction analysis exhibited the decrease of relative crystallinity, indicating that degradation of hardwood by a brown-rot fungus was in the advanced stages.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.74-82
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• 2010

Curtain stability without curtain contraction is critical for a successful operation in curtain coating, and this can be influenced by the change in particle dynamics and rheological properties of coating colors. In this study, polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) were added to control the rheology of GCC based curtain coating colors. Surface tension was increased slightly with increasing content of cobinder. Shear-thinning of viscosity was more pronounced for the CMC containing GCC coating colors. Complex modulus decreased when small amount of PVA was used as a cobinder, but it increased in other coating colors. Extensional viscosity was increased with increasing of the cobinder content, but CMC was more effective. Results indicate that pigment interaction with PVA is different from that with CMC. Dispersibility of coating colors was improved due to steric stabilization when small amounts of PVA was used, but flocculation occurred by bridging when the amount of PVA was increased. Dispersibility of coating colors was improved when small amount of CMC was added, while flocculation was observed by depletion effect when the concentration of CMC was increased in coating colors. Addition of cobinders at proper levels gave positive effects both in rheological properties and curtain stability. On the other hand, excessive amount of cobinders caused particle flocculation and this resulted in rheological and curtain stablity problems.

• Corrosion Science and Technology
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• v.18 no.2
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• pp.61-71
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• 2019

Flow-Accelerated Corrosion (FAC) is a phenomenon in which a protective coating on a metal surface is dissolved by a flow of fluid in a metal pipe, leading to continuous wall-thinning. Recently, many countries have developed computer codes to manage FAC in power plants, and the FAC prediction model in these computer codes plays an important role in predictive performance. Herein, the FAC prediction model was developed by applying a machine learning method and the conventional nonlinear regression method. The random forest, a widely used machine learning technique in predictive modeling led to easy calculation of FAC tendency for five input variables: flow rate, temperature, pH, Cr content, and dissolved oxygen concentration. However, the model showed significant errors in some input conditions, and it was difficult to obtain proper regression results without using additional data points. In contrast, nonlinear regression analysis predicted robust estimation even with relatively insufficient data by assuming an empirical equation and the model showed better predictive power when the interaction between DO and pH was considered. The comparative analysis of this study is believed to provide important insights for developing a more sophisticated FAC prediction model.