• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.10-18
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• 2000

To improve the physical properties of OCC (Old Corrugated Container) fibers, we used the mechanical pre-treatment on the fibers before refining . The mechanical action in the Hobart mixer induced high shear and compression on the fibers, which resulted in changes of fiber internal structure, and microcompressions on the surface of the fibers. We evaluated the amount of mechanical treatment on the fibers by fiber curl index for convenience. Four different refining techniques were applied to the pre-treated fibers (valley beater, Kady mill, PFI mill, and Impact refining) to find the best combination of the pre-treatment and the refining methods. Conclusions were summarized as followed. 1. Mechanical pre-treatment in Hobart mixer for more than 1 hour caused the increase of curl index of OCC fibers, and increased breaking length, burst index, and tear index the handsheets more than 10 % in this experiment. 2. Kady mill and PFI mill refining were effective in keeping fiber length from shortening Kady mill and Valley beater refining straightened out the fiber curls, and reduced the curl index. 3. Valley beating reduced fiber length very fast and generated fines more than other refining methods. 4. To increase breaking length and burst strength while keeping tear strength , combination of mechanical pre-treatment and Valley beating were most effective.

• Korean Journal of Agricultural Science
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• v.26 no.1
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• pp.21-30
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• 1999

To increase the strength properties of recycled fiber, especially OCC (Old Corrugated Container) in this study, we used the mechanical pretreatment on the fibers before refining. The mechanical action in the Hobart mixer induced high shear and compression on the fibers, which resulted in the breakdowns of fiber internal structure, and microcompressions on the surface of the fibers. We evaluated the degree of mechanical treatment by fiber curl index. Four different refining techniques were applied to the pretreated fibers (Valley beater, Kady mill, PFI mill, and Impact refining) to find the best combination of the pretreatment and the refining methods. Conclusions were summarized as followed. 1. In keeping the fiber length from shortening, Kady mill and PFI mill refining were effective. Kady mill and Valley beater application tended to straighten out the fiber shapes. 2. Valley beating increased the breaking length of the handsheets better than other methods, while lowering the tear strength most. The mechanical pretreatment increased breaking length about 10% in average irrespective of four different refining methods. 3. Tear strength was increased by the mechanical pretreatment and by the PFI mill refining. 4. Burst strength was increased by the mechanical pretreatment and by valley beating method. 5. In increasing the breaking length and burst strength while keeping tear strength, combination of mechanical pretreatment and Valley beating were most effective.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.151.1-151
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• 1999

No Abstract, See Full Text

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2000.04a
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• pp.153-155
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• 2000

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 1999.04a
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• pp.124-125
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• 1999

• Korean Journal of Environment and Ecology
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• v.26 no.5
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• pp.770-779
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• 2012

In order to verify the characteristics of vegetation structure in Jeolgu valley, Nakdongjeongmaek, we set up 29 plots(each plot area is $10m{\times}10m(100m^2)$. The survey site is located in around the valley and its range is about 3km section. The forest vegetation communities were analysed by TWINSPAN classification. The results of communities were classified 5 types such as Pinus densiflora community, deciduous broad-leaved tree community, Quercus variabilis community, Quercus mongolica community, Larix leptolepis community. The deciduous broad-leaved tree which prefer to moist environment and Quercus spp. has dominant in around the valley and the northern slope. In addition, Larix leptolepis community expect to maintain the present status for a while. However, the under story of Larix leptolepis community have expanded the influence of deciduous broad-leaved tree such as Fraxinus mandshurica, Morus bombycis, Acer mono and so on. Therefore, there will be developed next ecological succession by species of deciduous broad-leaved tree. The diversity index showed form 0.9665 to 1.2450. It were analyzed that diversity index of Jeolgu valley was higher than other places in Nakdongjeongmaek.

• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.237-246
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• 2001

To investigate the forest structure and to suggest the basic data of forest in the Dongwol Valley, the Gyeryongsan National Park, forty one plots were set up and surveyed. According to the analysis of classification by TWINSPAN, the community was divided by seven groups of Carpinus taxinora(I), Styrax japonica(II), Pinus densiflora A type(III), Quercus acutissima(IV), P. densinora-Q. valiabilis(V), p. densinora B type(Ⅵ) and Q. mongolica community(Ⅶ). The structure of communities were investigated using importance value. The survey results were summarized as follows: 1) the results of annual ring analysis revealed that the age of forest in the Dongwol Valley was about 30~50 years old,2) number of the average species was 15.6$\pm$4.7 and number of average individual was 124.9$\pm$36.4 per a plot(100$\textrm{cm}^2$). From the above results, it was anticipated that C. laxiflora will be climax species instead of Q. spp. and P. densinora.

• Journal of Environmental Science International
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• v.30 no.8
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• pp.693-702
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• 2021

The purpose of this study was to provide basic data for developing effective forest healing programs for retirees by identifying their characteristics and preferences. A survey was conducted on demographic characteristics, overall perceptions of forest healing, and preferences for forest healing programs, targeting a total of 258 retirees visiting a natural recreation forest and a healing forest. The results of the survey suggested that the awareness of the forest treatment program and the hope of participating in it were both high, but the experience of participating in the program was low. Among the forest healing programs, the order of preference was "Breath in the forest", "Wind bathing and sunbathing", and "Feeling negative ions in the valley". Based on these results, it is expected that the forest healing program for retirees will be used as basic data for development of such programs in the future.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.686-694
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• 2019

This study was carried out to identify the long-term changes to beech forest due to climate change in Ulleung-do. To study the traits of the stand structure of beech forest with micro-topography, we investigated the distribution of the basal area, important values, and indicated species in a small ridge between Albong basin and Seongin-bong peak, and 1-ha stands (20 m × 20 m, 25 sites) dominated beech species including on the upper slope and valley parts. The result showed that the indicator species characterizing the vegetation communities were Tsuga sieboldii, Rhododendron brachycarpum, and Mitchella undulata in the small ridge and Celtis jessoensis, Dryopteris crassirhizoma, and Ulmus laciniata in the valley part. Moreover, the individuals with the total DBH < 10 cm were more predominant in the small ridge and upper slope than in the valley part, the individuals with DBH = 10-25 cm were predominant in the small slope, and individuals with DBH = 25-45 cm and DBH > 45 cm were predominant in the upper slope. The reason for the predominant distribution of beech stand with DBH<10 cm in all terrains is suggested to be germination by nutritional propagation rather than secondary succession caused by artificial disturbances and seed propagation.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.73-86
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• 2001

Taking account of the structural variation on species composition according to the different topographic positions and aspects, the forest community attributes such as species composition, species diversity index, and similarity coefficient were comparatively analyzed for the three topographic positions and the four aspects in the natural deciduous forest of Mt. Gari area. The results are as follows 1. The most dominant species in the overstory were Quercus mongolica in the mid-slope, the ridge, and all aspects areas, however, the stands of the topographic positions were less similar than the stands of the aspects in species composition, because of the appearance of the specific domonant species such as Juglans mandshurica in the valley area and Pinus densiflora in the ridge area. 2. Among the three topographic positions, the mid-slope area had greatest species diversity index in overstory, but the index of the valley had greater value than those of mid-slope and ridge in mid-story and understory. The north-east area among the aspects had greatest the index in all canopy layers. However, The stands of the aspects showed more smaller variation than the stands of the topographic positions. 3. The ridge area showed greatest similarity coefficient value with the mid-slope area, but showed least similarity coefficient value with the valley. However, similarity coefficient among the topographic positions had much smaller value than similarity coefficient among the aspects.