• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.2
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• pp.12-20
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• 2004

This study was carried out from January 1998 to December 1999 to report the revegetation of cutting-rock slopes and a design standard in the highway cut-slopes. The field data was collected from the 67 sites cutting-rock slopes of highways, local roads, and field test. As the result of analyze, cutting-rock slopes revegetation measures were 16 types. There were Vine planting(3 types), Hydroseeding measures with seed-fertilizer-soil materials(5 types), Vegetaion-base spraying measures(5 types), and Stability measures(3 types). The factors affecting the plant coverage rates of cutting-rock slopes were the slope gradient, the slope width and direction. The plant coverage rate decreases in the condition of steep slope and long slope width and length(height). In addition, the plant coverage rates of the westward and southward were lower than that of the northward and eastward. Most dominant species were Zoysia japonica, Lespedeza cyrtobotrya, Lespedeza cuneata, Rubus crataegifolius, Miscanthus sinensis, Arrundinella hirta, Themeda triandra, and Oenothera odorata. Exotic species were Eragrostis curvula(Weeping lovegrass), Dactylis glomerata Orchardgrass), Lolium perenne(Perennial ryegrass), and Festuca arundinacea(Tall fescue). It is recommended to adjust the proposed factor as environment, topsoil, classification of rock, field condition and characteristic related with revegetation measures on slopes for the presentation of revegetation standard.

• Design & Manufacturing
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• v.16 no.4
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• pp.17-23
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• 2022

Recently, several studies are being conducted to achieve a curvature of 180° or more for the edge of the display glass. The thermocompression molding process is applied to the manufacture of curved glass, and high hardness G5 graphite is used as the mold material to withstand the impact applied to the mold. G5 graphite has high hardness and strong brittleness, which makes tool wear and surface damage easy during machining. Therefore, the demand for diamond-coated tools with good mechanical properties is increasing in the G5 machining field. In this study, the optimal cutting conditions and machinability of a nanodiamond (NCD) coated ball end mill being developed by a tool manufacturer were analyzed and evaluated. For this purpose, the same test was performed on the microdiamond (MCD) coated ball end mill and compared together. In summary, the machinability of MCD and NCD coated tools showed better cutting performance at a cutting speed of 282 m/min, a feed rate of 1,400 mm/min, and a radial depth of cut of 0.08 to 0.1 mm.

• Journal of Korean Society of Forest Science
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• v.94 no.1 s.158
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• pp.6-10
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• 2005

This study was conducted to understand the dynamics of naturally regenerated seedlings and saplings in 28years after selective cutting at natural Korean pine-broadleaved forests in Mt. Changbai. The number of naturally regenerated tree species was 16 species in 28 years after selective cutting. The appearance rate of naturally regenerated tree species was 56 percentage and the early-successional tree species of Acer ukurunduense, Acer mono, Acer pseudosieboldianum, Prunus padus var. pubescens, and Maackia amurensis were found in the first 10 years after selective cutting. The seedlings and saplings of shade-tolerant tree species of Pinus koraiensis, Acer mandshuricum, Ulmus laciniata were appeared and the appearance rate was higher than 75% after 15 years while it showed little changes from 19 years after selective cutting. The distribution density of seedlings and saplings of regenerated tree species in selective cutting area was 5,500~6,100 trees per hectare in the first 10 years, and it increased gradually along with the restoration of disturbed area and it could reach 7,500 trees per hectare after 15 years.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.785-790
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• 2015

As an alternative to large-scale clear cutting silviculture, strip clear cutting (SC) is being considered as a system compatible with ecological conservation and forest regeneration. In South Korea, application and effectiveness of SCC in varying forest types were rarely found. In this study, under the subject of strip clear cutting lands of pinus densiflora forest at Samcheok, Gangwon-do Province, the developmental aspect of low vegetation prior to and after deforestation and the correlation between environmental factor and pine regeneration were analyzed. The cover rate of understory vegetation was appeared to be increased after deforestation and rapidly increased two years after deforestation, and it was evaluated to be affected by vigorous tree species and photophilic species. From the perspective of relative importance value, Quercus mongolica, Artemisia keiskeana, and Rubus crataegifolius that influence the cover rate showed the inclination of continuous growth. The diversity of species showed increment inclination as well due to introduction and settlement of early transient species. As a result of analyzing the correlation between vegetation and environmental factor and generation of pine tree size, the soil exposure rate, intensity of light, and canopy openness showed positive relationship, and the understory vegetation cover and woody debris cover rate showed negative relationship.

• Korean Journal of Plant Resources
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• v.19 no.4
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• pp.530-536
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• 2006

Hardwood cutting propagation and early growth characteristics were investigated in order to develop the method of cutting propagation and to find out growth characteristics in the low altitude for in situ and ex situ conservation of Empetrum nigrum var. japonicum K. Koch, which is typical arctic alpine plants on Mt. Halla. The growth of roots and shoots was different depending on hormone concentrations or soil conditions. The survival rate, rooting rate, root growth, number of root and shoot growth increased with treatment of 100 mg/l or 500 mg/l NAA. Consequently, optimum condition of hardwood cutting was at treatment with 100 mg/l or 500 mg/l NAA. When plantlets from hardwood cuttings were exposed to the field condition, after 7 months survival rate was 73.3% without shading while $91.1{\sim}94.4%$ at shading conditions. In the green house, however, survival rate of plantlets were $95.6{\sim}97.8%$ without shading. The growth of plantlets was different depending on sites and shading conditions. Particularly, the best growth was obtained when the plantlets were grown in shading conditions. It indicates that relative humidity and light intensity are correlated with the growth in the low altitude area.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.110-116
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• 1988

The response of forage yield was studied with various growth indices to develop yield model and to determine optimum cutting time in three cultivars of orchardgrass. 1. Number of tiller per plant was the highest at 3rd cutting stage. But, it was decreased rapidly at 4th cutting stage. Leaf Area Index (LAI) was the highest at 3rd cutting stage. LAI was increased slowly during 15 days to 20 days after cutting and thereafter increased rapidly. 2. In dry matter yield over cutting stages, 1st cutting and 3rd cutting stages were higher yield than others. Change of dry matter yield was similar to that of LAI in all cutting stages. 3. Leaf Elongation Rate (LER) and Specific Leaf Weight (SLW) were reached to maximum at 20 to 25 days and 25 to 30 days after cutting, respectively. 4. Dry matte yield was highly correlated with LAI (r-0.905)and with CGR (r-0.962) over three cultivars. Also, LAI was significantly with LER. The best-fit yield model was obtained in multiple regression equation which included both dependent variables of LAI and CGR. 5. Optimum cutting times which were determined by the relationships between D.M. yield and LAI, and between D.M. yield and CGR, were ranged from 32 days to 36 days depend on each cutting stages.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.3
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• pp.110-116
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• 1988

The response of forage yield was studied with various growth indices to develop yield model and to determine optimum cutting time in three cultivars of orchardgrass 1. Number of tiller per plant was the highest at 3rd cutting stage. But, it was decreased rapidly at 4th cutting stage. Leaf Area Index (LAI) was the highest at 3rd cutting stage. LA1 was increased slowly during 15 days to 20 days after cutting and thereafter increased rapidly. 2. In dry matter yield over cutting stages, 1st cutting and 3rd cutting stages were higher yield than others. Change of dry matter yield was similar to that of LA1 in all cutting stages. 3. Leaf Elongation Rate (LER) and Specific Leaf Weight (SLW) were reached to maximum at 20 to 25 days and 25 to 30 days after cutting, respectively, 4. Dry matter yield was highly correlated with LA1 (r=0.905)and with CGR (r=0.962) over three cultivars. Also, LA1 was significantly with LER. The best-fit yield model was obtained in multiple regression equation which included both dependent variables of LA1 and CGR. 5. Optimum cutting times which were determined by the relationships between D.M. yield and LAI, and between D.M. yield and CGR, were ranged from 32 days t o 36 days depend on each cutting stages.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.32-44
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• 2001

The purpose of this study was to investigate the effects of Er : YAG laser on cutting efficacy and temperature changes of dentin. We used the dentin specimens of human premolars and molars which contain the physiologic saline and maintain the pulpal pressure in dentinal tubules. Each specimen was exposed to Er : YAG laser with non-contact handpiece type delivery system under different treatment condition of irradiation energy, pulse repetition rate, and exposure time. Two procedures were conducted by the presence of water flow during lasing. The specimens were grouped by thickness of dentin. We investigated the cavity pattern, volume, and temperature change of dentin specimen to determine the cutting efficacy and temperature rise of Er : YAG laser, and obtained following results. 1. Cutting volume of dentin was increased by increasing the irradiation energy, pulse repetition rate, and exposure time(P<0.05). 2. Margins of abulated cavities were sharp and clean and floors of cavities were conical in shape and showing smooth surfaces. Upper diameter of abulated cavities were increasing as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased. A few cracks were observed on abulated surfaces under treatment condition of laser parameter with 150mJ, 5Hz, and 5sec. 3. Temperature was increased as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased, and temperature rise was decreased as dentin thickness was increased(P<0.05). 4. Temperature rise was decreased under water flow compared with no water flow during laser exposure(P<0.05). From these results, we think that the method of using a Er:YAG laser would be effective and safe in cutting dentin for clinical application.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.6
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• pp.73-79
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• 2020

Although engineering plastics that are light-weight and have excellent mechanical performance have been widely applied in various industries in place of steel structures to reduce the burden of cost and time, there have been few studies related to their surface roughness. This study aims to evaluate the optimal effects of feed rate, cutting speed, and depth of cut as cutting parameters as well as nose angle on the surface characteristics of MC nylon in CNC lathe machining. To determine the best conditions under different nose radii, the experiments were performed based on the Taguchi L9(34) orthogonal array method, in which the resulting data was analyzed using the S/N ratio and ANOVA. Results indicate that the most significant contribution was feed rate followed by nose angle and cutting speed, whereas the depth of cut did not influence the performance. This study demonstrates that the suggested method for improving the surface finishing of MC nylon is efficient compared with results obtained from experimentation and prediction.

• Journal of the Korean Home Economics Association
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• v.20 no.1
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• pp.1-10
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• 1982

This experiment was made on the basis of the general observation that silk fabrics is flaccid in sun light. The purpose of this test is to examine efficiency between the processed thread and the unprocessed one after putting the later under the xenon-lit system, which produces continuous spectrum of bright white beam similar to sun light. (i) Color division of silk thread : white, yellow blue (ii) light division and irradiation time : sun lightlongrightarrow210 hrs, Xenonlongrightarrow50,100, 150 hrs. Under the above conditions each object was be tested with and extensometer, TENSILON Type III for the results of (a) the weight-expansibility curve of the silk thread (b) the relationship between cutting in tensity and maximum, weight (c) maximum expansion rate (d) the expansion energy of the tested silk thread (e) the beginning pull-stretch resistance rate of the tested silk thread (f) color difference after processing The results are illustrated in the appropriate tables and figures. Consequently the generalobservation that silk fabrics is flaccid is relevant only in terms of color. So for as Cutting-intensaty is concerned, it turned out to be less flaccid than in color. On the contrary when the untested silk thread was conpared with the xenon-irradiated ones, the latter proved itself to be more flaccid in cutting expansibility than the former. We have learned through this experiment that, after the all rounds of this test, the color tone and chroma of the colored materials remained without significant change, where as their color value changed to a large extent.