• Journal of dental hygiene science
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• v.13 no.3
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• pp.330-338
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• 2013

In order to explore microleakage in class V cavity based on different kinds of several dentin adhesive and composite resin, 2 kinds of composite resin was restored and exposed after applying 4 kinds of dentin adhesives. Deposited in methylene blue solution for 4 hours and cut in parallel with tooth longitudinal axis. By observing dye penetration level of enamel and dentin margins of each restored resin following conclusion was obtained. 1. In composite resin Filtek Z350XT Universal (3M/ESPE Dental Products, USA) in enamel margin, Easy Bond (3M/ESPE Dental Products) showed the lowest microleakage and this leakage was represented to be high in the order of Single Bond 2 (3M/ESPE Dental Products), Scotchbond Multi-Purpose (3M/ESPE Dental Products) and Cearfil SE Bond (Kuraray Medical Inc., Japan). In case of Filtek Z350XT Flowable (3M/ESPE Dental Products), Scotchbond Multi-Purpose showed the lowest microleakage and this leakage was represented to be high in the order of Single Bond 2, Clearfil SE Bond and Easy Bond. 2. In case of Filtek Z350XT Universal in dentin margin, Easy Bond showed the lowest microleakage and this leakage was represented to be high in the order of Scotchbond Multi-Purpose, Single Bond 2 and Clearfil SE Bond. In case of Filtek Z350XT Flowable, Scotchbond Multi-Purpose and Single Bond showed the lowest microleakage and this leakage was represented to be high in the order of Clearfil SE Bond and Easy Bond. 3. In all the groups excepting S-U group (Single Bond 2+Filtek Z350XT Universal), enamel margin showed more higher microleakage than that of dentin margin. 4. There was a difference between enamel and dentin margin among each group but it was not significant statistically (p>0.05). When summarizing this result, it is considered that composite resin and dentin adhesive could be applied selectively and particularly in case of applying 1-step self-etching dentin adhesive, this method would be advantageous for manipulation convenience and shortening of operation time.

• Korean Journal of Environment and Ecology
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• v.29 no.3
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• pp.431-440
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• 2015

This study investigated the correlation between the trees planted on the slope of the first landfill where the landfill was completed and the soil environment. 69 plots (($7{\sim}20m{\times}5{\sim}20m$) were planted with 26 kinds of major trees in the first landfill slopes for vegetation survey. The survey was conducted from 2007 to 2009. Soil analysis from 2007 to 2008 was made on the basis of the injured index and the indicator species were selected. Depending on the rate of growth of the indicator species, seven survey locations were selected for soil sample analysis. 10 tree species appeared to adapt to the landfill environment. Among them, the coniferous trees were Pinus thunbergii (Seedling) and Juniperus chinensis and the deciduous trees were Quercus aliena, Salix preudo-lasiogyne, Castanea crenata (Seedling), Prunus armeniaca var. ansu, Quercus acutissima, Chionanthus retusus, Liriodendron tulipifera (Seedling) and Celtis sinensis. 8 species of trees did not adapt well to the landfill environment. Among them, two kinds were coniferous, the other six kinds were deciduous. In addition, judgment on the other 8 species of trees as to whether they adapted well or not was postponed. The species for which judgment was postponed included one coniferous tree and seven deciduous trees. Indicator species of injured index was the species that have more than 25 % of the defect. The soil was collected from where Catalpa ovata, Sophora japonica, Albizzia julibrissin and Acer palmatum were planted for analysis. According to the soil analysis, the soil pH showed that the soil was alkaline. Regarding the three phases of the soil, most sample soil showed 60 % for the solid phase or 55 % for the solid phase but with less than 10 % of gas phase. The organic matter content was found to be 0.14 to 2.52 %.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.580-589
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• 2015

The artificially grown forests of larch, planted in accordance with the nationwide afforestation policy in the 1970s, are located inside national parks. This study intended to induce a forestation system by which the forests develop into an ecologically healthy and broadleaved ecosystem with broad species diversity. For this, the aspects of natural regeneration of broadleaves from 2010 to 2013 after thinning by density (30%, 50%, and 70%) in 2009 were surveyed using the larch forest in the Woljeong Temple region inside Odaesan National Park. There were no trees that were larger than 2 cm in in diameter at breast height among the trees recently introduced between 2012 and 2013. A significant number of herbs have been introduced to the subsurface alongside young arboreal trees species such as Bumalda bladdernut, Acer triflorum, Cornus controversa etc and shrubs. However, many woody species did not survive the competition with herbs and repeated withering and regeneration. The number of woody species generated within the 30% cutting area was 440 species in 2013 and this figure has been increasing twofold each year. The number of woody plants within the 50% cutting area also showed an upward tendency and most plants did not survive in the competition with herbs and Sasa borealis and withered in only 1 ~ 2 years after generation. Unlike other thinning areas, the 70% cutting area showed 608 broadleaved trees, reflecting a decrease from 748 trees in 2012. This appeared to be attributed to the luxuriance of S. borealis and the sharp increase of fatsia following the inflow of total sunlight to the forest floor. Herbs were hardly generated due to the influence of S. borealis. Regarding the density for thinning at 50% or upper height, the forest treatment division shall maintain a proper density in the course of inducing artificial forestation of larch into natural broadleaved forests considering the luxuriance of sasa borealis and herbs due to the inflow of total sunlight to the forest floor.

• Korean Journal of Environment and Ecology
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• v.32 no.2
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• pp.165-175
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• 2018

The purpose of this study is to provide the basic data such as distribution status, growth characteristics, and the structural characteristics of forest stands for the systematic conservation and management of relict forest trees (stem girth of 300cm or larger) established naturally in Gangwon Province, Korea. The survey showed that 434 individuals of 19 species (conifers: 228 individuals of 4 species, broad-leaved trees: 206 individuals of 15 species) were distributed in Gangwon Province, and Taxus cuspidata was the most abundant among them with 203 individuals or about 46.7 % of the total. The stem girth was average of 404cm (conifers: 373cm, broad-leaves: 421cm), and Tilia amurensis with multi-stemmed growing on Sorak mountain range had the largest stem girth at 1,113cm. The average height and the crown width of relict forest trees were 15.4m and 10.0m, respectively. Although the environments of relict forest trees showed a slight difference by species, the relative appearance frequencies of most trees were high in the environments where the altitude was higher than 1,000 m, slope degree was greater than $25^{\circ}$, the slope faced north, and microtopography was at the upper of slopes. Regarding the stand characteristics of relict forest trees per unit area ($/100m^2$), the average total coverage was 294% (max. 475%), the total average number of species was 36 species (max. 60 species), the average species diversity index (H') was 2.560 (max. 3.593), the average canopy closure was 84.8% (max. 94.6%), and the average basal area (/ha) was $52.7m^2$ (max. $116.4m^2$, relict trees $30.0m^2$, and other trees $22.7m^2$). The analysis of the dynamics of the forest stands where relict forest trees were growing showed four types of the maintenance mechanisms of relict forest trees depending on the supply pattern of succeeding trees: "Low-density but persistent type (Quercus mongolica, Abies holophylla, Tilia amurensis, and Pyrus ussuriensis)," "Long ago stopped type (Pinus densiflora)," "Recently stopped type (Abies nephrolepis, Quercus variabilis, and Betula schmidtii)," and "Periodically repeated types of supply and stop (Salix caprea and Quercus serrata).".

• Korean Journal of Agricultural Science
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• v.25 no.2
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• pp.160-167
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• 1998

This study was carried out to estimate the effect of NPK fertilization on tree seedling growth and chemical properties of soil. Seedlings of Betula platyphylla var. japonica and Fraxinus rhynchophylla were planted in May 1998 in the nursery at Gariwang mountain, Kangwondo, and seven NPK fertilizer plots(4, 12, 28, 60, 124, 252, and $508g/m^2$) and one non-fertilized plot were used to meet the study objectives. Seedlings of Pinus koraiensis and Acer mono were planted in April 1998 in plastic pots of nursery at Chungnam National University, and seven NPK fertilizer plots(0.5, 1.5, 3.5, 7.5, 15.5, 33.5 and 63.5g) and one non-fertilized plot were used to meet the study objectives. To estimate the relative growth ratios of the seedlings, height and root collar diameter of the seedlings were measured after planting and also in October 1998. Soil samples were collected in October 1998 from the nursery of Gariwang mountain and the plastic pot of the nursery of Chungnam National University. The relative growth ratios of height and root collar diameter in Betula platyphylla var. japonica, Fraxinus rhynchophylla and Acer mono were greater in all fertilized plot than non-fertilized plot, but there was no difference in relative growth ratio of height and root collar diameter of Pinus koraiensis between the fertilized and non-fertilized plots. NPK fertilization increased soil P and K, decreased exchangeable Ca and Mg, and base saturation, and pH. Fertilization resulted in no difference in total soil N between the fertilized and non-fertilized plots of nursery of Gariwang mountain, but increased in total soil N in plastic pots. Fertilization increased the growth of hardwood species and had changed soil chemical properties of this fertilizer trials.

• Journal of the Korean Wood Science and Technology
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• v.24 no.1
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• pp.34-47
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• 1996

Veneers of two nominal thicknesses, 1.5 and 2.5mm, were rotary peeled from Japanese larch (Larix leptolepis). Dahurian larch (Larix gmelinei) and Radiata pine (Pinus radiata) bolts unheated and heated in the water vat temperature of $66^{\circ}C$ by rising a final temperature at 10cm core of $60^{\circ}C$ to remain core diameter of 11.4cm. 1.5 and 2.5mm thick veneer cut from the heated Japanese larch were significantly thinner than those of the unheated bolt and 2.5mm thick veneer cut from the heated Dahurian larch were significantly thicker than that of the unheated bolt. 1.5mm thick Dahurian larch veneer and 1.5 and 2.5mm thick Radiata pine veneers showed insignificant difference between the unheated and heated bolts, respectively. Check distance on the loose side of 1.5mm thick veneer cut from the heated Radiata pine was significantly wider than that of the unheated bolt. However check distances on the loose side of 1.5 and 2.5mm thick Japanese larch and Dahurian larch veneers and 2.5mm thick Radiata pine veneers showed insignificant difference between the unheated and heated bolts. Also the depth of check on the loose side of three species showed insignificantly difference between the unheated and heated bolts. Arithmatic mean deviation($R_a$) and maximum height($R_{max}$) of the profile on the loose side of dried veneer by preheating the bolt compared with unheated bolts were different among apecies and between veneer thickness. The preheating treatment slightly affected qualities of these thin veneers such as 1.5 and 2.5mm. The yield of 2.5mm thick veneer from the heated radiata pine was significantly higher than that of the unheated bolt. However the yield of 2.5mm thick veneer for other two species and 1.5mm thick veneer for three species showed insignificant difference between the unheated and heated bolts. The yield of 2.5mm thick veneer for three species were higher than those of 1.5mm thick veneer. The average yields of green veneer of Japanese larch. Dahurian larch and Radiata pine were 57.1, 55.1 and 54.0 percent, respectively. Variables such as initial MC. drying time and veneer thickness had strong effect for Japanese larch veneer, less effect for Radiata pine veneer and nuch less effect on final MC for Dahurian larch veneer in jet drying. Correlation between the current MC and the drying time of Dahurian larch with low variation of initial MC was higher than those of Japanese larch and Radiata pine veneer with high variation of initial MC in high temperature drying. Thickness shrinkages of 2.5mm thick veneer for Japanese larch and Radiata pine were higher than those of 1.5mm thick veneers, but shrinkages of Dahurian larch veneer were similar between two nominal veneer thicknesses.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.135-143
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• 2015

This study evaluated fuel properties of composite materials which were prepared by mixing a waste activated carbon from the used purifier filter with torrefied wood powder. Wood species of the raw material of torrefied wood powder are oak wood (Quercus serrata Thunb. ex Murray) and pine wood (Pinus densiflora Siebold & Zucc). And the treatment conditions used for this study were 300 s, 450 s, and 600 s at $200^{\circ}C$ for the wood roaster. Also, the mixing ratios are 5 : 95, 10 : 90, 15 : 85, 20 : 80, 40 : 60, 60 : 40 and 80 : 20 (waste activated carbon : torrefied wood powder). The fuel properties such as highly heating value (HHV), elementary analysis and ash content were evaluated. The results obtained are followings; 1. Despite the same treatment condition of wood roasting, pine wood has higher carbon contents than oak wood. Therefore, pine wood indicated the optimum carbonization at low temperature and short treatment times. 2. The gross calorific value and ash content increased as the mixing ratio of waste activated carbon increased. 3. Mixtures of the waste activated carbon and torrefied wood powder showed greater gross calorific value than those of the mixtures of waste activated carbon and the untreated wood powder. Also, the pine wood resulted in higher heating value that thaose of the oak wood. 4. When composite fuels that were composed waste activate carbon and wood powder are used, higher temperature conditions are required because the combustion is incomplete at $800^{\circ}C$ and 4 hours. 5. The increasing rate of the gross calorific value of mixtures of waste activated carbon and untreated wood powder is higher than does the mixtures of waste activated carbon and torrefied wood powder. Also, this phenomenon is more obvious for pine woods. Therefore, an optimal mixing ratio of waste activated carbon was determined to be between 5% and 10% (wt%). Also, this condition satisfied the requirement of the No.1 grade of wood pellet.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.397-405
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• 2009

In this study, we investigated the potential of producing bioethanol from Liriodendron tulipifera by using oxalic acid pretreatment. Amounts of fermentable sugars, mostly xylose and glucose, in the liquid fraction (hydrolysate) was $40.22g/{\ell}$ after the biomass was pretreated with 0.037 g/g of oxalic acid for 20 minutes at $160^{\circ}C$. Production amounts of ethanol was $8.6g/{\ell}$ from the 72 hours of simultaneous saccharification and fermentation (SSF) on solid fraction of the pretreated sample. At the same condition, when the reaction time increased to 40 minutes, $32.66g/{\ell}$ of fermentable sugars in the hydrolysate and $9.5g/{\ell}$ of ethanol was produced from the process of pretreatment and SSF. As a result of analyzing the fermentation inhibitors, such as acetic acid, 5-HMF, furfural and total phenolic compounds, as the reaction time increased, the amount of the fermentation inhibitors in the hydrolysate increased. Production of the fermentation inhibitors was more affected by initial concentration of oxalic acid rather than reaction time. $3.39{\sim}5.78g/{\ell}$ of acetic acid was produced by pretreatment with 0.013 g/g of oxalic acid, and the amount of furfural produced by decomposition of xylose was 2~3 times higher than the amount of 5-HMF produced by decomposition of glucose. All the hydrolysates contained more than $5g/{\ell}$ of total phenols considered as the degradation product of lignin. Therefore, by analyzing the amount of fermentable sugars and fermentation inhibitors in the hydrolysate, and producing ethanol from SSF of solid fraction of the pretreated sample, the biomass pretreated with 0.037 g/g of oxalic acid for 20 minutes at $160^{\circ}C$ can be expected to produce the most ethanol.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.149-160
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• 2007

KoFlux Gwangneung Supersite comprises complex topography and diverse vegetation types (and structures), which necessitate complementary multi-disciplinary measurements to understand energy and matter exchange. Here, we report the results of this ongoing research with special focuses on carbon/water budgets in Gwangneung forest, implications of inter-dependency between water and carbon cycles, and the importance of hydrology in carbon cycling under monsoon climate. Comprehensive biometric and chamber measurements indicated the mean annual net ecosystem productivity (NEP) of this forest to be ${\sim}2.6\;t\;C\;ha^{-1}y^{-1}$. In conjunction with the tower flux measurement, the preliminary carbon budget suggests the Gwangneung forest to be an important sink for atmospheric $CO_2$. The catchment scale water budget indicated that $30\sim40%$ of annual precipitation was apportioned to evapotranspiration (ET). The growing season average of the water use efficiency (WUE), determined from leaf carbon isotope ratios of representative tree species, was about $12{\mu}mol\;CO_2/mmol\;H_2O$ with noticeable seasonal variations. Such information on ET and WUE can be used to constrain the catchment scale carbon uptake. Inter-annual variations in tree ring growth and soil respiration rates correlated with the magnitude and the pattern of precipitation during the growing season, which requires further investigation of the effect of a monsoon climate on the catchment carbon cycle. Additionally, we examine whether structural and functional units exist in this catchment by characterizing the spatial heterogeneity of the study site, which will provide the linkage between different spatial and temporal scale measurements.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.3
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• pp.108-118
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• 2012

To investigate the responses of yellow poplar (Liriodendron tulipifera L.) seedlings to the interactive effects of the elevated atmospheric $CO_2$ level and nitrogen addition, we measured biomass, photosynthetic pigments, photosynthesis, and the contents of nitrogen (N) and carbon (C) from the seedlings after 16 weeks of the treatments. Yellow poplar seedlings were grown under the ambient ($400{\mu}mol\;mol^{-1}$) and the elevated (560 and $720{\mu}mol\;mol^{-1}$) CO2 concentratoins with three different N addition levels (1.2, 2.4, and $3.6g\;kg^{-1}$) in the Open Top Chambers (OTC). The dry weight of the seedlings enhanced with the increased N levels under the elevated $CO_2$ concentrations and the increment of the dry weight differed among the different N levels. Photosynthetic pigment content of the yellow poplar leaves also increased with the increase of the $CO_2$ concentration levels. The effects of the N levels on the photosynthetic pigment content, however, were significantly different among the $CO_2$ levels. Photosynthetic rates were affected by the levels of $CO_2$ and N concentrations. Stomatal conductance and transpiration rates increased with increasing $CO_2$ concentration. The carboxylation efficiency of the seedlings without N addition increased under the higher $CO_2$ concentrations whereas that with N addition decreased under the elevated $CO_2$ concentrations. Nitrogen and carbon uptake in leaf, stem, and root increased with the elevated $CO_2$ concentration level and N addition. In conclusion, under the elevated $CO_2$ concentrations, physiological characteristics and carbon uptake of the yellow poplar seedling were improved and increased with N addition.