• Korean Chemical Engineering Research
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• v.61 no.2
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• pp.302-311
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• 2023

This study was conducted to evaluate the applicability of castor oil (CSO) as a natural wood preservative. CSO was treated into wood blocks prepared with domestic and imported wood species using a vacuum-pressure method, and then treatability, leachability and decay resistance of the CSO-treated wood blocks were examined. Although CSO was penetrated effectively into wood blocks of all wood species, the CSO-treatability was the highest in Western hemlock, followed by Japanese larch (LA), soft maple and Mongolian oak due to the difference of its anatomical structure. Except for LA, the more retained, the more leached during a saline water-immersing process for 48h. The use of ethanol added to reduce the viscosity of CSO affected negatively the treatability and leachability of wood blocks. Decay resistance, which was evaluated by the weight loss of wood blocks exposed against Fomitopsis palustris (FOP) and Trametes versicolor, of the CSO-treated/leached wood blocks was superior to that of control. Especially, most of wood blocks treated with preserving solution composed of only CSO (CSO-2) did not decayed and showed a very low weight loss against FOP. The decay resistance results from CSO retained in wood blocks after leaching. The retention of CSO could identify using the observation of X-ray microscope. Length of wood strips, which were treated with CSO-2 and then immersed in saline water for 2 weeks, hardly changed in all cutting directions. In addition, weight gain and length-swelling rate of the wood strips were extremely low compared to those of control. These results indicate that moisture resistance of the wood strips was improved by the CSO treatment. It is concluded that the treatment of CSO using a vacuum-pressure method provides the decay resistance and dimensional stability of wood, and thus CSO can be used as a natural wood preservative on various indoor and outdoor circumstances.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.250-259
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• 1982

The Larch was known unsuitable species for the wood cement board owing to its some inhibitory substances. Therefore this research was carried out to evaluate the effect of pretreatments and chemical additives on the properties of woodflake cement board from Japanese larch (Larix leptolepis) grown in Korea. In order to improve the board qualities, the woodflakes were treated by cold water or dilute NaOH solutions(0.1, 0.5, and 2.0%), and also some chemicals($CaCl_2$, $Al_2Cl_3$ and $Na_2SiO_4$) added to the wood cement mixture. The results obtained are summarized as follow; 1. The wood cement boards from the woodflake treated with 0.1% NaOH showed remarkable higher bending strengths and internal bonding strengths than those from the flake pretreated with cold water. 2. The bending strengths showed over $60kg/cm^2$, i.e. the standard strength of JIS A-5417, with pretreatments of NaOH over 0.1% and additive of $CaCl_2$ 3.0%. The maximum strengths showed at about 0.5 of every additives. 3. Addition of $CaCl_2$ and $Al_2Cl_3$, in the case of pretreated wood with NaOH above 0.1%, had effects on increasing the internal bonding strengths of sample boards. 4. The thickness swellings became decreasing along with the increasing NaOH pretreatment concentntration. 5. The equilibrium conditions of the sample boards pretreated with NaOH over 0.1% and added with $Al_2Cl_3$ and $CaCl_2$ were maintained at 9.0~10.5% moisture contents. 6. The specific gravity of the samples showed close relationships with strength properties.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.19-25
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• 2004

This study was carried out to investigate a radial distribution of moisture contents (MCs) within a log cross section (LC) during oven-drying of 3 mm-thick circumferential slices cut from several domestic softwoods LCs.For Korean red pine, drying rate of sapwood slices during oven-drying represented much higher values than that of heartwood slices, and so sapwood with higher green MC early reached below fiber saturation point (FSP) rather than heartwood did. However, this distribution of moistures did not last for long duration. For Japanese larch, green MC of sapwood was approximately three times higher than that of heartwood. This similar distribution in MC was lasted until about 20% average MC. The MC was around uniform throughout the sapwood of Ginkgo when green and during oven-drying, although it was somewhat fluctuated. For Japanese cedar, the heartwood with so low moistures around FSP would begin to shrink from the beginning stage of drying, but the sapwood above hygroscopic MC prevents the heartwood from shrinking, and consequently, the heartwood or the transition wood goes into tension stress. The results for Japanese cypress showed that the green MCs of the sapwoods were much lower than those for heartwoods, and then this trend was continued until about 20% in average MC. For Chinese thuja, the green MCs of sapwoods were about 2 times as high as those of heartwood, but this along the radial gradient in MC rapidly became gentle during oven-drying.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.8-17
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• 2000

Structural glued laminated timbers were manufactured from Japanese larch(Larix leptolepis) lumber. The effect of various factors, such as finger joint, strength of lamination, on the strength properties of glulam was investigated. When only MOE of lamina was used as input variable for the estimation of strength properties of glulam, the deviations between actual and simulated results were increased with the number of lamination, because the effects of variance of lamina properties on the strength estimation of glulam were cumulated with the number of lamination. Therefore, to estimate the MOR of glulam more careful approach was needed. Besides, both MOE and MOR of lamination were used as input variable to compare the effect of input variable. In the case of finger jointed lamination was located in tension zone, MOE of glulam was some effected, because of the variation of MOE of lamination and the deficiency of information for knot. In the case of finger jointed lamination wasn't located in tension zone, more exact estimation was possible than the case of finger jointed lamination was located in tension zone. From the results, it was concluded that more exact estimation of strength properties of glulam could be obtained by considering effects of both finger joint and knot.

• Journal of the Korean Wood Science and Technology
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• v.31 no.5
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• pp.72-79
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• 2003

In reliability based design(RBD) method, the distribution characteristics of mechanical properties of material are basic input variable. Therefore, distribution type and parameters of mechanical properties should be determined accurately. Until now, the properties were derived from tests with small, clear specimens. However, the test conditions should emulate as nearly as possible the way in which the timber would be used in practice and the test results should, as closely as possible, reflect the structural end use conditions to which the timber products would be subjected. In this study, structural timbers (38mm by 140mm, 3.0m long) were graded by visual assessment of growth characteristics and defects. And then bending tests were conducted on 498 structural size timbers. For each grade, the distribution type and the parameters of mechanical properties were determined for each grade. For the determination of best-fit distribution type, comparing of square error between distribution types and KS test were conducted. Best-fit distribution type of bending strength(MOR) is weibull distribution for all grade. In case of MOE, normal distribution is best-fit.

• Journal of the Korean Wood Science and Technology
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• v.9 no.3
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• pp.7-15
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• 1981

A Japanese larch has been reforested very much in Korea, but it is not used as a wood resources for paper pulp by now. So this study is carried out to utilize the larchwood for paper pulp manufacture through the Asplund pulping process. The experiment on increasing in the brightness of the pulp is made through the addition of $MgSO_4$, $ZnSO_4$, $Al_2(SO_4)_3$, and KI as a cellulose stabilizer in chip treatment with caustic soda which is followed by high-temperature defibration and conventional peroxide bleaching (5% NaOH plus 2% additive salt per wood in cold pretreatment), or in high-consistency (30%) pulp bleaching of hydrogen peroxide and peracetic acid (100% acitve oxygen per lignin) for conventional one. The results obtained are as follows: 1. The solution of 0.5% additive salts had different pH by the sort of bases that was pH 5.7 in $MgSO_4$, liquor, pH 4.9 for $ZnSO_4$, and pH 2.9 for $Al_2(SO_4)_3$, and in the precepitation of bases which ranged to pH 6-13 for $MgSO_4$, pH 5-12 for $ZnSO_4$, and pH 3-10 for $Al_2(SO_4)_3$. 2. The cellulose stabilizer affective in high-consistency peroxide bleaching was KI, $MgSO_4$, and $ZnSO_4$, but has made a little improvement in de lignification and brightness of pulp in comparison with no addition. 3. The higher alkalinity in the chip treatment has made the higher strength and brightness of larchwood Aspiund pulp instead of downing the pulp yield. And the effective compound for cellulose stabilizer in caustic soda pretreatment of chip was $ZnSO_4$, $Al_2(SO_4)_3$ and KI in order for the conventional peroxide bleaching after Asplund pulping. 4. Therefore, the more effective additives for cellulose stabilization in high-temperature defibration of larchwood suppose to be $ZnSO_4$, $Al_2(SO_4)_3$, and KI, while KI and $MgSO_4$ for peroxide bleaching.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.239-249
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• 1982

The outlines of superior stands, including species mixed, age classes, canopies, and ecological conditions of the stands, were examined in the forests of west Germany, Sweden, and Netherland. The establishment schemes of tree seed orchards for the production of high genetic quality seed were also investigated in the present study. 1. The meteorological conditions, abundant in precipitation and high in relative humidity, prove it to be oceanic climate characteristics in the Scandinavia located in high latitude and north-western part of Europe. The photo periodical characteristics following to day-length and the frost times determine the patterns of tree growth and distribution as well as the tree adaptability due to bud-setting and bud-flushing in Sweden forest. 2. The European forests are generally characterized by dense multistoried forest type composed of upper stories of tall tree species such as Norway spruce, fir, Scots pine and beech, lower stories of shade tolerant poles and saplings of spruce, fir, beech, and floor vegetations covered with birch, oak and hornbeam etc. 3. The single tree selection method and group shelterwood method are commonly applied for silvicultural system but shelterwood method and clearcutting method practiced partially in limited area. Badischer Femelschlagbetrieb and Bayerischer Femelschlagbetrieb are popularized to the regeneration of Schwarzwald but selection method applied in part. 4. Tree cuttings are properly limited so as not to exceed annual increment volume for the sustained yield and the preservation of ecosystem in European forest management. Land preservation and recreation function are more interested with the promotion of wood production in the forest management. 5. Careful attentions are paid to the reforestation of the introduced exotic species, such as Douglas-fir, red oak, pines from America, Japanese larch, Italian poplar etc., with concern against the insect and pest damage, and the meteorological damage. 6. Some intensive studies on tree improvement, such as selection of plus tree, selection of plus stand for seed collection, provenance trial, progeny test of clone, hybrid seed orchard for clone complexing, are performed in the countries and the great part of the seed required for reforestation are supplied from the seed orchard established in Sweden and Netherland.

• Journal of Korean Society of Forest Science
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• v.54 no.1
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• pp.1-24
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• 1981

Kangweon-Do is rich in sightseeing resources. There are three sightseeing areas;first, mountain area including Seolak and Ohdae National Parks, and chiak Provincial Park; second eastern coastal area; third lake area including the watersheds of North Han River. In this paper, several methods of forestation were studied for landscaping the North Han River watersheds centering around Chounchon. In Chunchon lake complex, there are four lakes; Uiam, Chunchon, Soyang and Paro from down to upper stream. The total surface area of the above four lakes is $14.4km^2$ the total pondage of them 4,155 million $m^3$, the total generation of electric power of them 410 thousand Kw, and the total forest area bordering on them $1,208km^2$. The bordering forest consists of planned management forest ($745km^2$) and non-planned management forest ($463km^2$). The latter is divided into green belt zone, natural conservation area, and protection forest. The forest in green belt amounts to $177km^2$ and centers around the 10km radios from Chunchon. The forest in natural conservation area amounts to $165km^2$, which is established within 2km sight range from the Soyang-lake sides. Protection forest surrounding the lakes is $121km^2$ There are many scenic places, recreation gardens, cultural goods and ruins in this lake complex, which are the same good tourist resources as lakes and forest. The forest encirelng the lakes has the poor average growing stock of $15m^3/ha$, because 70% of the forest consists of the young plantation of 1 to 2 age class. The ration of the needle-leaved forest, the broad-leaved forest and the mixed forest in 35:37:28. From the standpoint of ownership, the forest consists of national forest (36%), provincial forest (14%), Gun forest (5%) and private forest(45%). The greater part of the forest soil, originated from granite and gneiss, is much liable to weathering. Because the surface soil is mostly sterile, the fertilization for improving the soil quality is strongly urged. Considering the above-mentioned, the forestation methods for improving landscape of the North Han River Watersheds are suggested as follows: 1) The mature-stage forest should be induced by means of fertilizing and tendering, as the forest in this area is the young plantation with poor soil. 2) The bare land should be afforested by planting the rapid growing species, such as rigida pine, alder, and etc. 3) The bare land in the canyon with moderate moist and comparatively rich soil should be planted with Korean-pine, larch, ro fir. 4) Japaness-pine stand should be changed into Korean-pine, fir, spruce or hemlock stand from ravine to top gradually, because the Japanese-pine has poor capacity of water conservation and great liability to pine gall midge. 5) Present hard-wood forest, consisting of miscellaneous trees comparatively less valuable from the point of wood quality and scenerity, should be change into oak, maple, fraxinus-rhynchophylla, birch or juglan stand which is comparatively more valuable. 6) In the mountain foot within the sight-range, stands should be established with such species as cherry, weeping willow, white poplar, machilus, maiden-hair tree, juniper, chestnut or apricot. 7) The regeneration of some broad-leaved forests should be induced to the middle forest type, leading to the harmonious arrangement of the two storied forest and the coppice. 8) For the preservation of scenery, the reproduction of the soft-wood forest should be done under the selection method or the shelter-wood system. 9) Mixed forest should be regenerated under the middle forest system with upper needle-leaved forest and lower broad-leaved forest. In brief, the nature's mysteriousness should be conserved by combining the womanly elegance of the lakes and the manly grandeur of the forest.