• The Journal of the Korean dental association
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• v.48 no.11
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• pp.813-818
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• 2010

Since MTA has many beneficial properties such as biocompatibility, great sealing capacity, antibacterial effects, low cytotoxicity, and stimulation of formation of mineralized tissue, it has been widely used as the material of choice in root-end filling, apexification, pulpotomy, perforation repair and so on. However, despite its favorable characteristics, MTA presents working properties which are less than ideal. The resulting cement from the mixing of powder and water is difficult to manipulate, and its setting time has been reported to be 2 h 45 min whereas the working time is <4 minutes. Additional moisture is also required to activate the setting of the cement. Moreover, according to recent studies, the physical properties of MT A may be hampered by acidic environment or blood contamination. Therefore, practitioners may have surprisingly worse results than they expected when they are not fully acquainted with the characteristics and manipulation method of MTA.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.5
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• pp.1-9
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• 1995

The purpose of this study is to develop a computer simulation program for analyzing load transmission characteristics of a helical gear system in design stage. In this analysis, the rotational delay, load distribution, root stress, and contact area are investigated. That is, the influence function of deflection is obtained by finite element analysis and the influence function of approach and gear tooth error are considered. Load distribution, rotational delay, and contact area are calculated by solving load-deflection equation which includes these influence functions and tooth error, and the influence function of the bending moment is obtained by finite element analysis. The root stress is calculated by the load distribution and the influence function of the bending moment. The results of the simulation are cross-checked through a specially designed experimental set-up.

• Korean Journal of Plant Resources
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• v.26 no.6
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• pp.709-717
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• 2013

The objective of this study was to examine the effect of root pruning intensity in combination with different initial seedling size on the growth of transplanting seedlings of Quercus acutissima. One-year-old seedlings were divided into three groups depending on their height, i.e. small (< 15 cm), medium (25-35 cm) and large size (35 cm <). Root of seedlings was pruned by three intensity such as, leaving 5 cm (severe), 10 cm (medium) and 15 cm (light) of taproot from the root-collar. After one year, we investigated survival rate, height and root-collar diameter (RCD) increment and final shoot dry weight. Also we measured characteristics of newly developed lateral roots such as number, total length, dry weight and diameter. Severe root pruning showed the lowest survival rate in all seedling size. Height increment, RCD increment and shoot dry weight were decreased with increasing intensity of root pruning. Seedlings of medium and light root pruning showed similar above-ground growth and dry weight of lateral roots. More large seedlings showed good survival rate, height increment and final shoot dry mass in all root pruning intensity. Therefore, one-year-old seedlings of Q. acutissima should be pruned taproot by 10 cm and transplanted to obtain excellent performance and increase the efficiency of transplanting work. Based on the findings of this study, it is important that applying to different root pruning intensity depending on initial seedling size for producing 2-year-old seedlings with excellent growth and high quality.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.12a
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• pp.59-59
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• 2020

Salix gracilistyla has a characteristic of fast growth especially in the river side or infertile soil, showing a lot of lateral branches and a strong root system among the Salix. spp. On the basis of results observed, we provide several growth characteristics of S. gracilistyla among some selected provenances. In two-year results, root collar diameter ranged from 33.5 mm to 56.7 mm. Taeback showed the lowest value, and Jeongseon and Hoengseong were higher than the other areas in the traits above. Height growth was the lowest in Samcheok and the highest in Wonju. To examine growth and development of lateral branches is important because S. gracilistyla has a lot of lateral branches which account for high biomass production. Length of lateral branch showed high variation, in which the highest number was observed in Yeongwol and the lowest in Samcheok. Many lateral branches were shown in Wonju. Preliminary study on biomass resources evaluation, we analyzed correlation between volume and length, and volume and root diameter. High correlation was observed between root diameter and plant volume. And we compared the observed volume with the caculated volume by regression formula. To evaluate Salix species as biomass resources, it is needed to survey growth characteristics continuously and adopt selection of individuals or families of high biomass and caloric values by reliable data. In addition, Salix spp. can be also applicable to selection breeding regime because of feasible propagation and fast growth.

• Korean Journal of Plant Resources
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• v.16 no.1
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• pp.49-54
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• 2003

Effects of cutting time and scions section on shooting and plantlets growth characteristics were investigated to increase plantlets products by root cuttings in lacquer tree. Shoot induction from scion section was developed lately as it planted in earlier season. However, shooting rates were over 84% or more in cut planting on 15, 25 March and 5 April than sinee 15 April. Shoots were developed evenly as late cut planting. Generally, plant height, branch number, leaf number, stem diameter, and leaf area per plantlets was excellent in cut planting on 25 March and 5 April. Shooting rate from the root scion varied greatly by root sectionings. The rate of the 10 cm-long-scion was reached 84％, whereas only 54％ in no trimmed root scion after 10 weeks of cutting. Regenerated plantlets from root scion without cut were slightly good in shape, but their height, number of branch per plantlets, and stem diameter were not significant.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.248-257
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• 2014

The objectives of this study were to identify the root plate dimension of wind-uprooted trees and to analyze the relationship among wind direction, aboveground and belowground properties of the trees. The root plates of 77 Japanese larches (Larix kaempferi) and 24 Korean pines (Pinus koraiensis), which were uprooted by a typhoon in 2012, in the Taehwa Experimental Forest of Seoul National University, Korea, were investigated. The results showed the root plate shape could be assumed to be an oval or a circle in above view, and half an ellipse in side view, respectively. Also, the number and surface area of individual roots in root plates were greater in uprooting direction than in non-uprooting direction. The results of correlation analyses between aboveground and belowground properties indicated DBH had more significant correlation with belowground properties than tree height. Finally, simple linear relationships were derived for significantly correlated tree aboveground and belowground properties.

• Korean Journal of Medicinal Crop Science
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• v.13 no.6
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• pp.241-244
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• 2005

This study was carried out to compare growth characteristics, and extract and crude saponin contents of 4-year-old ginseng cultured by direct seeding and transplanting cultivation at several farms of the main producing district, Geumsan and Eumsung. Though root weight per plant of direct seeding cultivation was lower than that of transplanting cultivation, but yield of the former was higher than that of the latter owing to high rate of survival plant and Leaf Area Index. Dry matter partitioning ratio of direct seeding cultivation was high in primary root and low in secondary root because direct seeding cultivation elongated the length of primary root, while it suppressed the growth of secondary root. Ratio of rusty root was decreased in condition of direct seeding cultivation, while the contents of extract and crude saponin were lower than that of transplanting cultivation.

• Applied Biological Chemistry
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• v.15 no.1
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• pp.49-57
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• 1972

Varietal difference in root distribution and other root characteristics were investigated under fold and water culture condition. The results were as follows: 1. IR667 showed funnel type of root distribution in soil profit while Jinheung had barrel type, and each type appearance was more distinguishable with fertilizer application. 2. Root weight per tiller was smaller in IR667 than in Jinheung and IR667 had more root in 0 to 5cm of soil depth but Jinheung had more in 5 to l0cm depth. 3. Horizontal distribution of root was dencer near to stem base without fertilizer than with fertilizer in both IR667 and Jinheung indicating structural construction for intensive nutrient uptake. Between varieties this 'dence to stem base' trend accompaning 'dence to wide spacing side' was greater in IR667 without fertilizer and these were quite true with fertilizer in Jinheung. 4. The decreasing rates of root and ear weight by fertilizer application were greater in IR667 than in Jinheung. This and other characteristics indicated that the root of IR667 is likely to be panicle-number type comparing with Jinheung. 5. The root of IR667 had lower oxidizing power of ${\alpha}-naphthylamine$ than that of Jinheung indicating weaker resistance to reductive soil but cation exchange capacity of water-cultured root was higher in IR667 suggesting stronger nutrient uptake. 6. The content of phosphorus and especially potassium in root were higher with fertilizer but lower without fertilizer in IR667 than in Jinheung indicating that IR667 is more sensitive to root environment. 7. The contents of N, K and CEC were increasing toward root tip while P content was decreasing. The root from surface soil had higher N and K content than that from subsoil. The contents of N,P,K, and CEC of root at harvesting stage were about 1.0%, 0.1%, 0.5% and 15me/100g at dry weight base, respectively.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.547-555
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• 2014

This study was carried out in order to investigate the germination and the early growth characteristics of Parasenecio firmus. Seed pre-treatment before the each experiment was carried out by shading treatment (with drying at room temperature (DRT), drying at low temperature (DLT) and water soaking (WS) for 48 hours). Experiment was performed by shading treatment (full sunlight, 35%, 50%, 75%, and 95% shading). Seeds of Parasenecio firmus were surveyed the highest germination rate (61.1%) in full sunlight with WS (overall 25.7~61.1%). Height was surveyed the highest under 95% shading. And root collar diameter was surveyed the highest in full sunlight. Fresh weights (leaf, shoot, root and total) were the highest under 50% shading. Dry weights (leaf, shoot and total) were the highest under 75% shading. It was indicated the lowest leaf, shoot, root and total under 95% shading. Leaf growth (leaf area, leaf length, leaf width and leaf thickness) and root growth (total root length, root project area, root surface area, root diameter and root volume) were good under 35%~75% shading, but the lowest under 95% shading. As a result of surveying the whole experiment, seed of Parasenecio firmus grows well under 50%~75% shading after germination by high sunlight with water soaking (WS).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.2
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• pp.147-154
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• 1989

The experiments were carried out to compare the growth characteristics of excised seminal roots in Japonica type, Indica- Japonica hybrids and its parents. Based on the modified culture medium by Kawata et al., several levels of pH. sucrose and casamino acid were varied in the culture media. The excised root length at 27$^{\circ}C$ incubator was little different between Japonica type and Indica-Japonica hybrids, but at 30$^{\circ}C$ incubator the excised root elongation of Indica-Japonica hybrids was much better than that of Japonica type. The dry matter weight of excised root in Indica- Japonica hybrids was significantly heavier than in Japonica type at both 27 and 30$^{\circ}C$ incubators. The difference of dry root weight between Japonica type and Indica- Japonica hybrids was caused from the number of lateral roots, especially the root numbers of 25 cm length. The main and lateral seminal root growth of Japonica type grew best at the lot of 0.2 percent casamino acid. However, the lots of 0 and 0.2 percent casamino acid showed good results in the main and lateral excised root growth. respectively of Indica-Japonica hydrids. The growth of excised roots was better in Indica-Japonica hybrids than in Japonica type at even various levels of pH, sucrose and casamino acid. Between the parents of Indica - Japonica hybrids, the excised root growth of Indica type was more predominant than that of Japonica type, and the effect of casamino acid on the excised root growth in the formar was similar to that of Indica type. This result indicated that the growth characteristics of excised seminal roots in Indica Japonica hybrids were derived from the parent, Indica type.