• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.36 no.5 s.108
• /
• pp.62-68
• /
• 2004

The amount of non-lignin components in unbleached and oxygen-delignified kraft pulps and their impact on lignin determinations was investigated. The lignin analyses investigated were kappa number and Klason lignin in conjunction with acid-soluble lignin. The species investigated were loblolly pine, and aspen. The non-lignin components that impacted on lignin determination were residual extractives and hexenuronic acid in unbleached and oxygen-delignified kraft pulps. In the hardwoods, significant amounts of extractives remained after kraft pulping and oxygen delignification. These residual extractives in the hardwood pulps had an impact on the lignin determination, more so on the acid lignin method than kappa number. Hexenuronic acid only impacts on kappa number determination both softwood and hardwood pulps, not on acid lignin. Hexeneuronic acid contributed as lignin content more in aspen than pine pulps, and more in oxygen-delignified than unbleached kraft pulps. Impact of hexenuronic acid on should be corrected both softwood and hardwood pulps for accurate kappa number.

• Journal of the Korea Furniture Society
• /
• v.26 no.2
• /
• pp.179-185
• /
• 2015

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood G. biloba, ring-porous wood A. altissima, and diffuse- porouswood D. kaki. In radial direction, ray cells and in longitudinal direction tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents (MC). The length, lumen diameter, pit diameter, end wall pit diameter and the numbers of end wall pits determined for the flow rate. The liquid flow in the those cells was captured via video and the capillary flow rate in the ones were measured. Vessel in hardwood species and tracheids in softwood was found to facilitate prime role in longitudinal penetration. Radial flow speed was found highest in ray parenchyma of G. biloba. Anatomical features like the length and diameter, end-wall pit numbers of ray parenchyma were found also responsible fluid flow differences. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Therefore, the average liquid penetration depth in longitudinal tracheids of G. biloba was found the highest among all cells considered in D. kaki and A. altissima.

• Journal of Plant Biotechnology
• /
• v.3 no.2
• /
• pp.45-57
• /
• 2001

Trees have the ability to undergo secondary growth and produce a woody body. This tree-specific growth is affected by the secondary vascular system and the developmental continuum of secondary phloem and xylem. Secondary growth is one of the most important biological processes on earth. Considering its economic and environmental significance, our knowledge of tree growth and development is surprisingly limited. Trees have received little attention as model species in plant science, as most Plant biology questions can be best addressed by using herbaceous model species, such as Arabidopsis. Furthermore, tree biology is difficult to study mainly due to the inherent problems of tree species, including large size, long generation time, large genome size, and recalcitrance to biotechnological manipulations. Despite all of this, one must rely on trees as models to study tree-specific questions, such as secondary growth, which cannot be studied effectively in non-woody model species. Recent advances in genomics technology provide a unique opportunity to overcome these inherent tree-related problems. Several groups, including our own, have been successful in studying the biology of wood formation with a variety of hardwood and softwood species. In this article, 1 first review the current understanding of tree growth and then discuss the recent attempts to fully explore and realize the potential of molecular biology as a tool for enhanced understanding of secondary growth.

• Journal of the Korean Wood Science and Technology
• /
• v.45 no.4
• /
• pp.409-418
• /
• 2017

This work attempted to manufacture glued-laminated timber (Glulam) bonded with melamine-urea-formaldehyde (MUF) resin adhesives at various melamine contents from 20% to 50% under high frequency (HF) heating for a very short time. Two preparation methods were employed to prepare MUF resin adhesives with different melamine contents: one-batch method of synthesizing MUF resins in a single batch, and two-batch method of mixing urea-formaldehyde (UF) resin with melamine-formaldehyde (MF) resin that had been synthesized separately. As the melamine content increased, the gelation time and peak temperature of MUF resins decreased. The adhesion performance of plywood showed that the one-batch MUF resin adhesive with 50% melamine content only satisfied the standard requirement of water resistance. Thus, the one-batch MUF resin adhesive with 50% melamine content was applied for bonding wood lamina from four softwood species such as Japanese larch, Korean red pine, Korean pine and Japanese cedar to manufacture Glulam under HF heating. All Glulam samples bonded with the one-batch MUF resin adhesives with 50% melamine content except those from Korean Red Pine satisfied the requirement in water soaking or boiling water delamination test as an exterior grade Glulam. The presence of rosin in Korean Red Pine was believed to be responsible for its poor adhesion. These results showed that the one-batch MUF resin adhesives with 50% melamine content provided acceptable water resistance with exterior grade Glulam manufactured under HF heating.

• Journal of Korean Society of Forest Science
• /
• v.81 no.2
• /
• pp.124-138
• /
• 1992

This study was carried out to estimate long-term demand functions, and to project consumption of roundwood to the year 2030, using time series data for the period 1970-1990. Especially, the unique features of this study are in the estimation of demand functions for roundwood by species group and by end-use with help of dummy variables. It also, attempts to show how dummy variables can be utilized for improving the estimation result. The result of this study reveals that hardwood roundwood consumption is being substituted by softwood roundwood due to the rapid increase in the relative price of softwood, and this trend is expected to continue in the near future. The consumption of roundwood by mining industry is projected to fall as the coal :mining is expected to decline. The parametric estimates of timber demand function by species group and by end-use indicate that the demand for timber in Korea is more responsive to the performance of domestic economy as a whole, represented by GDP in this study, than to other variables such as own and substitute prices. The effects of population growth and substitute prices could not be determined.

• Journal of the Korean Wood Science and Technology
• /
• v.16 no.4
• /
• pp.40-47
• /
• 1988

Our plywood manufacturing industries which entertained prosperous stage in late 1970's have come to be in face of the problems of conceedingly obtaining good quality logs and yield up-grading, which is considered by future-replaceable forest resources. In view of this point, manufacturing characteristic on softwood plywood using Japanese larch, pitch pine as domestic plantation species, and western hemlock as foreign species was studied. In this study, veneer- and plywood manufacturing yields were discussed in relation to log properties and veneer defects (knots). The summarized conclusions were as follows: 1. The majority of sample logs belonged to second grade on the standard. And, eccentricity of larch was the highest 11%, about 2 times those of pitch pine, hemlock. 2. Knot frequency of occurrence of larch reached 19% within log height 8m, and pitch pine 13% within 4m. Correspondingly, the log height of larch available for plywood manufacture was higher by about 2 times that of pitch pine. 3. In the knot types, most of knots of larch appeared dead, whereas those of pitch pine and hemlock appeared live. In size of knots, larch and hemlock showed relatively small 1-2cm dia. by 70% or more and pitch pine did the larger 24cm by 65%. Generally the more knot emerged in the inner side of veneer than the outer. 4. Plywood manufacturing yields by peeling with spindle revolution lathe were 37% in larch > 32% in hemlock> 26% in pitch pine. S. Jointed core veneer yields by peeling with outer perimeter back-up lathe were 55% in hemlock> 53% in larch> and 48% in pitch pine.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.6
• /
• pp.1204-1209
• /
• 2001

As a basic study to find bioactive principles for the hypolipidemic effect from natural sources, various biological influences of MeOH extracts of Thuja accidentalis L. and Juniperus chinensis var. horizontalis Nakai on rats were examined. The concentrates obtained from the organic layer and aqueous layer fractions of each species were orally administered to rats and then their effect on the body weight, organ weight, serum lipids profile, and blood glucose concentration were examined. Among the samples tested, the organic layer of Juniperus chinensis var. horizontalis exhibited the possibility of the hypolipidemic effects. The corresponding layer was chromatographed to give three fractions and reexamined their effects on rats. The results demonstrated that the fraction corresponding for the R$_{f}$ 0.4~0.7 which was the mixture of many minor components showed the effect of lowering the blood-lipid bevel effectively without any side effects. Besides, communic acid, identified from and isolated as a major component of the species exhibited the possibe hypolipidemic effects.s.

• Korean Journal of Plant Resources
• /
• v.15 no.3
• /
• pp.269-278
• /
• 2002

To establish the mass propagation methods of Weigela subsessilis,, a promising native plant species for horticultural use, several factors influencing rooting from stem cuttings were evaluated. Softwood cuttings showed best rooting rate, 70~77%, in all the cutting media tested, 2.8 times more than hardwood cuttings in which perlite was best medium. The rooting from hardwood cuttings was promoted by higher concentration of all growth regulators used,500 mg.L$^{-1}$ NAA being the best with 80%. More than 80% of softwood cuttings treated by growth regulators produced roots, especially 100, 500, and 1000mg.L$^{-1}$ NAA producing 97％. Roofings from semi-wood cuttings was enhanced by all the growth regulators, except 1000 mg.L$^{-1}$ concentration in which rooting was reduce. Higher rooting rate was obtained by higher concentration and longer soaking duration of NAA in case of hardwood cutting. Softwood cutting showed 100 ％ rooting by soaking treatment with 500 mg.L$^{-1}$ NAA for 3 min. Rooting rate of semi-hardwood cuttings was promoted by higher concentration and longer soaking with growth regulators, However, the degree of improvement was lower than soft and hardwood cutting.

• Journal of the Korean Wood Science and Technology
• /
• v.15 no.1
• /
• pp.22-55
• /
• 1987

This study was executed to offer the basic data needed to plywood industry in Korea for the future based on microscopic wood features as our previous paper reported by the macroscopic features. Microscopic wood characteristics for 50 species selected by the viewpoint of possible utility in future were examined and described by the species. Also, keys for the identification based on microscopic features were briefly prepared and presented by gymnosperm and angiospenn respectively.

• Journal of architectural history
• /
• v.16 no.1
• /
• pp.9-28
• /
• 2007

We investigated the changes in the species of the woods used for Korean ancient and historic architectures, which include prehistoric excavated relics and existing wooden buildings in South Korea. The species data were collected from various sources such as excavation and repair reports, journal papers, and a few unpublished documents. We divided the building Periods as Paleolithic, Neolitic, Bronze Ages, Iron Age/Three Kingdoms, Koryo, Joseon (early, middle, late) and modem periods. In prehistoric periods, hardwoods were major species. Oak (Quercus spp.) woods dominated (94 percent in average); the others (5%) were Juglans mandshurica, Platycarya strobilacea, Castanea crenata, and few softwoods(1%). During Iron Age and Three Kingdom periods, oaks remained as a major species (57%) and others Platycarya strobilacea(21%), Castanea crenata(13%), and Pinus spp. (6%). The oak woods decreased in Koryo period and they occupied only 1.1%. Instead of oaks, pine (Pinus spp., 71%) and Zelkova serrata (22%) dominated in Koryo. In early and middle Joseon periods, pine woods (73%) remain as a major species and the others were oaks (14%) and Zelkova serrata (9%). As late Joseon came, the pine woods occupied more than 88%. In the late 19th and early 20th centuries, a few boreal species such as larch (Larix spp.) and spruce (Picea spp.), which grow in cold area, were found. We believe they were transported from northern Korea. The existing buildings in Korea are mainly from Joseon period and a few from late Koryo periods. During these periods, pine woods were used for most buildings. For such reason, pine woods were known as 'representative materials for historic buildings'. but earlier times, broad-leaved trees, i.e., oak and Zelkova woods were major materials. The changes in building materials resulted from both climate and human impacts. The dry climate and disturbed forests induce more pines in the mountains. We also compared the wood qualities of the species and found that Zelkova woods were superior ones and deserved more planting for future demands in the repair for historic buildings.