• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.547-551
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• 2008

The study aimed to develop a cryopreservation method for long-term storage using mature somatic embryo of Japanese larch. In this study, desiccation treatments significantly affected re-induction rates of embryogenic tissue (ET) from dried somatic embryos. In the effect of different dehydration temperature and duration on the re-initiation ET. the highest frequency was shown when somatic embryos were dehydrated at $25^{\circ}C$ for 2 (45.5%) or 1 day (43.3%), respectively. In addition, low temperatures [$4^{\circ}C$, 2 days (44.2%) or 3 days (43.5%)] were marked higher ET initiation. After that, the initiation value was declined with dehydration duration. For comparison of different relative humidity on re-induction frequency of ET, the best re-induction (43.5%) was obtained from somatic embryos pre-dried at $(NH_4)_2SO_4$ (RH 79%). Both $Na_2HPO_4$ (RH 97%) and $Na_2CO_3$ (RH 88%) treatments were showed the similar rate, 34.6, 34.2%, respectively. However the lowest rate (19.6%) was observed in distilled water (RH 100%). In comparison of the various storage temperatures and duration of the dried somatic embryos, the highest frequency (66.9%) of re-initiation was obtained when somatic embryos were cryopreserved for one day. However, the frequency was gradually decreased as the time length of storage increased regardless of types of storage. None of ET re-initiated when stored at $4^{\circ}C$ for 1, 2 and 84 days.

• Journal of the Korean Wood Science and Technology
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• v.39 no.2
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• pp.125-131
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• 2011

The characteristics of radio-frequency/vacuum drying Japanese larch boxed heart round logs with 150 mm and 210 mm in diameter and 2,500 mm in length, subjected to compressive loading, after the pretreatment of kerf were investigated. The results of this study were as the follows: The drying time of about 120 hours~130 hours was needed from green to about 15 percent of moisture content. The gradient of final moisture content for all specimens was very gentle in both longitudinal and transverse directions owing to dielectric heating. The surface checks seriously occurred although the occurrence extent of surface check for the kerfed specimens was slight compared with that for the control specimens because drying stress was relieved by kerf. The occurrence of surface checks for the L-specimen was more serious than that for the S-specimen.

• Journal of Korea Foresty Energy
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• v.20 no.2
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• pp.41-45
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• 2001

Japanese Larch(Larix kaempferi) was treated with aqueous solutions(30%, 40%, 50%) of polyethylene glycols(PEG, #1000, #1500, #4000, #6000) for the dimensional stabilization. The antiswelling efficiency(ASE) was measured for the evaluation of the dimensional stabilization. The weight percent gains(WPGs) of the woods treated with 40% solutions were higher than those of the others, and the highest WPG was achieved by treatment with 40% solution of PEG #1500. The ASE decreased with increasing molecular weight of PEG. ASE of woods treated with PEG #1000 and PEG #1500 were higher than those of the others.

• Journal of Plant Biotechnology
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• v.36 no.3
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• pp.230-235
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• 2009

The effect of auxin transport inhibitor (TIBA and PCIB) or auxin synergist (phloroglucinol) on somatic embryo maturation and germination in Japanese larch (Larix leptolepis) was examined. The addition of 15.8 mg/L ABA+5.0 mg/L PCIB showed most promoted the maturation of cotyledon -staged somatic embryos (177.7/90 mg ESM). In contrast, with treatment of 5.0 mg/L PCIB or 5.0 mg/L TIBA, no somatic embryos were obtained. Considering from this result, PCIB or TIBA alone could not substitute for exogenously supplied ABA for maturation of somatic embryos. In the test of below concentration of 5.0 mg/L PCIB, the highest results were recorded in 15.8 mg/L ABA+2.0 mg/L PCIB (109.3/90 mg ESM) or 15.8 mg/L ABA+5.0 mg/L PCIB (103.7/90 mg ESM). However, 5.0 mg/L phloroglucinol (0/90 mg ESM) or no ABA addition (3/90 mg ESM) had little influence on somatic embryos maturation. In germination study, the highest frequency of plantlet regeneration obtained from the somatic embryos which had matured on 15.8 mg/L ABA+5.0 mg/L PCIB (67.9%). However, either 5.0 mg/L PCIB nor 5.0 mg/L TIBA resulted in obtained from plantlets.

• Journal of the Korean Wood Science and Technology
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• v.33 no.2 s.130
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• pp.8-16
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• 2005

In an effort to encourage the development of value added engineered applications for small diameter round timber, research is being conducted to develop and verify design guidelines for connections with specific application to round timbers. The objective of this research is to provide potential users with a number of viable connection options applicable in the fabrication of engineered, round wood structural components and systems. Target uses include trusses, built up flange beams and space frames. This paper presents information on a mortised steel plate connection fabricated using powder driven nails in 6 cm diameter Japanese Larch. The design load for PDN connections are around 1.3 kN per nail with strip and 0.8 kN per nail without stripe. The design model for PDN connectors could be chosen by the number of nails. If the number of nails are more than the critical number between nail bearing and wood failure, the wood failure model could be the way to design the structure safely. The wood failure model needs to be studied more but the model could be the tensile and cleavage mixed failure model.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.7-17
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• 1991

The feasibility of treating three softwood(Japanese larch pitch pine, and Korean pine) thinned logs by double-diffusion treatment processes was investigated. Some posts were incised before immersion, and others were imersed in hot copper sulfate solution. Comparison among species indicated that. in general, pitch pine was most treatable and Japanese larch least treatable. For all three species, almost all treatment schedules gave consistently good penetration and high net retention, but very steep gradient of preservative distribution. As expected, the treatability was increased by the extension of immersion time, increased concentration of treating solution, incising. and heating of the first solution. Of the variables tested, it appears that heating of the first solution is the most important. From the data in this paper, it may be concluded that, if the first solution is not heated, the best schedule is #3. If the first solution is healed. it appears the best schedules are #10 or #11. Since heating of the first solution improves the treatability. schedules # 10 or :#11 are recommended if the cost of heating might be justified. The data presented in this paper indicate that double-diffusion treatment processes seem to offer a promise as a comparatively effective and easy-operating method of treating thinned logs for the small-scale production of treated stock.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.151-159
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• 2007

This study was conducted to investigate the effects of thinning on changes in stand characteristics and understory vegetation in a silvopasture practiced Japanese larch plantation in the Research Forest of Kangwon National University, Korea. Three different thinning intensities (64%, 35%, and control) were applied. Before and after thinning, the understory plant species increased its number from 48 (7 tree species, 7 shrubs species, 28 herbaceous species, and 6 woody climbers) to 100 (11 tree species, 15 shrub species, 67 herbaceous species, and 7 woody climbers). Thinning made plants invade easily on the forest floor, and plot A (325 stems/ha) had much higher number of undersory species than those Of plot B (575 stems/ha) and control plot (1,150 stems/ha). In three years after thinning, understory aboveground biomass (kg/ha) of herbs were 523 for control, 1,230 for plot B, and 1,288 for plot A. The canopy coverage had remarkable influence on the understory biomass production, resulting in relatively small amount of herbage production on control plot. The differences were statistically significant between thinned plots and unthinned plot, but there were no significant differences among the thinned plots (p<0.05).

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.4
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• pp.436-442
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• 2011

In this study, the Total Volatile Organic Compounds (TVOC) emitted from wood-based panels were compared by two analytical methods using the GC/FID and the GC/MS. Japanese Larch, Yellow Poplar, Particle Board (PB) and Medium Density Fiberboard (MDF) were selected as target materials. Major compounds emitted from the panels were Toluene, ${\alpha}$-pinene, ${\beta}$-pinene and limonene. In case of TVOC using GC/FID method, MDF E2 (1,497 ${\mu}g/m^3$) revealed the highest concentration among all wood-based panels, while Japanese Larch (1,772 ${\mu}g/m^3$) showed the highest value with respect to GC/MS method. Furthermore, it was found that the amount of VOC emitted from panels was different depending upon analytical methods. This significant difference was attributed to analytical sensitivities of GC/FID and GC/MS for various VOC. Besides, it was found that the composition ratios of main VOC compounds were not significantly different.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.88-95
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• 2008

The shrinkage of wood members after construction has been a greater and common concern in wooden buildings with the durability. Particularly, the traditional structure applying solid members actively is easily exposed to the shrinkage that caused by the joints, members, and walls. Moreover, even though domestic larch glulam members are widespread recently in the post-beam construction, the shrinkage (swelling) problem is still the critical defect on the wooden structures by the moisture content change in Korea. Various moisture contents were applied for the specimens to survey the dimensional changes for Japanese larch solid and glulam specimens, and the glulam specimens varied in the number of their laminations. Test results showed that glulam specimens with over 3 bonding layers showed good dimension stabilities. Therefore, to solve the shrinkage problem, sufficient drying fitted to the end-use service conditions should be conducted on the solid or glulam members can be applied.

• Journal of Korean Society of Forest Science
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• v.34 no.1
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• pp.21-30
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• 1977

Japanese larch (Larix leptolepis) is one of main timber species in Korea that could find much plantation and growing stands on all over the country. It is thought to be in meaningful that a guiding diagram for density control of Japanese larch stands is made to estimate easily the density conditions in the quantitaive, ecological and economic viewpoint. Sample plots for this study are selected from the stands that have not been thinned in recent years, and mean height, mean diameter, dominant height, tree numbers per hectare and stem volume of mean tree are calculated from the each sample plots among total 165 plots In this study, especially, the theory of slenderness of mean tree are applied, that have been identified through the results of the spacing trial. Relative growth characteristics of this species are calculated from the general logistic curve and its formula is $Y=ax^b$. Relatwion between the measured items are found out as follows: 1. Relation between the mean height and tree numbers per hectare by slender class is showing the high correlation as table 1 and fig. 2, and between mean diameter and tree numbers per hectare is also high correlation as table 1 and fig 3. 2. The stem volume can be correctly estimated from height in case that slender class may be known, as showing in table 3 and fig. 4. 3. The stem volume can be more correctly estimated from the relation with $D^2H$ as formula, $Log_e\;V=0.9569\;Log_eD^2H-9.8431$, and relation between stem volume of single tree or volume per hectare and tree numbers per hectare are as following formulas: $Log_e$ stem volume=9.5026-1.6800 $Log_e$ tree numbers per hectare $Log_e$ stem volume per hectare=9.4911-0.6784 $Log_e$ tree numbers per hectare. Stem volume of mean tree, tree numbers per hectare and stem volume per hectare correspond to the mean tree height are calculated to slender class as table 5, 6, 7. Through the above steps, the diagram for density control of Japanese larch are produced as fig. 9. It is thought that this diagram could be applied to control the density of Japanese larch stands.