• Journal of Korea Foresty Energy
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• v.25 no.2
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• pp.34-41
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• 2006

In this study, new engineered woods, which can be used as structural members, are developed using three different mechanical jointing methods with large elements produced from logs in a high yield. Flitches of relatively large cross-section are produced from small or medium diameter logs, and are joined with steel bolts, wood dowesl and steel lag bolts. Static bending tests are performed for these three types of built-up beams. Built-up beams joined with steel bolts show $514kgf/cm^2$ for MOR and $129,000kgf/cm^2$ for MOE, which are close to those of typical structural glulams. In case that wood dowels and steel lag bolts are used, elements are isolated as load increases and resists the applied load individually. Therefore, built-up beams joined with wood dowels or steel lag bolts show almost half of steel bolts for both MOE and MOR. From the results of this study, it was indicated that bending properties of engineered woods manufactured using mechanical jointing methods with large elements are influenced mainly by jointing performance between each elements.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.79-85
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• 2019

'Experiments in Art and Technology' Group was established in the mid-20th century, and then developed the larger interdisciplinary experiments into the range of art world and its outside field. The motive power of group's activities was the collaboration between artists and engineers traversing the boundary between old different disciplinary conventions. E.A.T was officially launched in 1967 by the engineers Billy $Kl{\ddot{u}}ver$ and Fred Waldhauer and the artists Robert Raushenberg and Robert Whitman. They performed various possibility of material, technology, and engineering available to contemporary art. By reflecting the function of art and technology in society, eventually they developed the methodology of new aesthetics which had organic relationship with contemporary world. In this sense, this research have its academic significance. This paper firstly examined the socio-cultural context of emerging the E.A.T. group as a representative model for convergent practice, and verified the fact that the collaboration between artists and engineers had produced the expansion of artistic expression as well as new relationship among art, engineering, and society by considering E.A.T's various projects. Therefore, I will refer the E.A.T. group as an exemplary model for concrete method of collaboration that contemporary discourses about convergence need.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.71-78
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• 2005

For the utilization of chestnut inner bark as forest biomass, this studies have been carried out cleary investigated about phenolic compounds from the diethyl ether solubles and ethyl acetate solubles of hot water extract from chestnut inner bark. 3 compound were isolated and their structures were identified by spectroscopic methods. They were known compounds, 3,5-dihydroxybenzoic acid, 3,4,5-trihydrixybenzoic acid and catechin. Electron donating ability (EDA) of 3 compounds were investigated. Gallic acid and catechin were found to higher EDA than control, ascorbic acid and $\alpha$-tocopherol in 10 ppm, and especially gallic acid has very higher EDA, 21 times than ascorbic acid. This gallic acid of chemical structure were substituted with free phenolic hydroxyl groups at meta and para position. It was supposed that phenolic hydroxyl groups in chemical structure was a EDA factor.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.40-49
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• 2004

Phyllostachys pubescens planted in the Nambu Forest Experiment station in Jinju city of Gyongnam province was used, to investigate the physical and mechanical property of bamboo in this study. The ages of the P. pubescens were 1, 2 and 3 years, respectively. This experiment was carried out in August and January. The P. pubescens were divided into upper, middle and lower parts according to the growing points. The physical and mechanical properties of the P. pubescens were investigated before and after treatment of hot water and microwave irradiation. 1. The upper part of the P. pubescens indicated the highest static MOE according to the growing points. The range of the static MOE was from 70,000 to 110,000kgf/cm². 2. When P. pubescens were treated with hot water of 95℃, the ratio of softening was about 10~30%. 3. As microwave irradiation time was increased, the MOE values was decreased in both green and water-saturated bamboos. For the irradiation time of 20 and 30 seconds, the static MOE of P. pubescens was decreased up to about 50% comparing with non-treated.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.9-18
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• 2004

This study was carried out to find the efficient methods for preventing resin exudation from spruce board during high temperature environment service.In the dry-air oven test, in-use temperature related to resin exudation of 110℃ could be obtained by the appropriate kiln drying without any special treatment, and the in-use temperature of the radio-frequency/vacuum (RF/V)-dried boards was about 20℃ higher than that of the conventional kiln-dried boards.In the autoclave test, resin exudation was not found from any board dried in the conventional kiln and in the RF/V kiln after the low pressure steam explosion (SE) treating, while for the control resin exudations were more severe in the autoclave test above 130℃ than in the dry-air oven test. It, therefore, would be suggested that resin exudation during high temperature service condition can be prevented more effectively by super-heated steaming green boards than by high-temperature drying boards with low moisture.

• Journal of the Korean Wood Science and Technology
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• v.30 no.1
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• pp.25-33
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• 2002

Improvement of density profile and sound absorption capability of particleboard was attempted. Three types of hot pressing methods examined ; flat-platen pressing method (A-type pressing), hot pressing in forming box (B-type pressing), and hot pressing set up jagged caul in forming box (C-type pressing). The raw materials were larch(Larix leptolepis (S, et. Z.) Gorden) shavings, phenol formaldehyde resin, and the particleboard perforated with stair type. The physical and mechanical properties such as specific gravity, bending strength (MOR), internal bonding strength (IB) and sound absorption coefficients were examined. The results are summarized as follows : 1) The MOR and internal bonding strength of the board pressed in forming box were higher than those of flat-platen pressed board. 2) The minimum density to average density ratio in thickness direction which pressed in forming box showed about 923%, in the case of 35 mm commercial particleboard and 50 mm flat-platen pressed board, its values showed about 66.4% and 865% respectively. 3) Sound absorption coefficients of the particleboard perforated with stair type were higher than those of flat-plated pressed board and commercial particleboard.

• Journal of the Korean Wood Science and Technology
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• v.32 no.1
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• pp.17-27
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• 2004

Cholesterol inhibitory activity was investigated to develop the functional food from edible forest resources such as Allium victorialis var. platyphyllum and other 12 species. Among tested samples by enzyme-linked immunosorbant assay (ELISA), leaf extracts of A. victorialis var. platyphyllum inhibited 73.9% of the activities of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) which is the highly regulated and major rate-limiting of the cholesterol biosynthesis pathway. Moreover, those extracts inhibited 76.7% of squalene synthase which catalyzes the head-to-head condensation of two farnesyl pyrophosphate molecules to form squalene in the biosynthesis of cholesterol. In order to find out the compounds which would play a key role in inhibitory activity of cholesterol, kaempferol and quercetin were isolated from the dichloromethane soluble fraction of extracts of A. victorialis var. platyphyllum. Kampferol, quercetin and each soluble fraction was also subjected to the test of the mRNA expression of HMG-CoA reductase and squalene synthase by reverse transcriptase-polymerase chain reaction (RT-PCR) assay, respectively. By treating both enzymes with 10 ㎍/㎖ of kaempferol and quercetin for 24 hours, respectively, the mRNA expression was not observed, suggesting that both compounds inhibited the biosynthesis of cholesterol at mRNA level. In this regard, it could be inferred that cholesterol inhibitory activity of A. victorialis var. platyphyllum was derived from kaempferol and quercetin. Both compounds have already been found in many plant extracts including hardwood and softwood, but it might be first known that they have cholesterol inhibitory activity.

• Journal of the Korean Wood Science and Technology
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• v.5 no.1
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• pp.3-8
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• 1977

A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potentially valuable resource. As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Quercus grown in Korea can be enhanced by learning its anatomical structure and properties. In this paper, bark characteristics of Quercus grown in Korea are described. In bark anatomy, general features such as color of rhytidome, exfoliating form, color of periderm, arrangement of periderm, and thickness of the inner and outer hark. etc., arc discussed. Studies on the microscopic structure include sieve tube, companion cell, parenchyma, pholem fiber, ray, periderm(phelloderm, phelloogen, phellem), sclereid, and crystal, etc. The results may be summarized as follows: 1. In general characteristics of rhytidomes, exfoliating is not easy and sclereids are distint to the naked eye. Inner bark is thicker than that of outer bark except in case of Q. variabilis. 2. It is not clear to distinguish between phelloderm and phellogen in Quercus bark. The phellem is developed conspicuously in Q. variabilis but that of Q. accutissima is composed of thinwalled phellem and thickwalled stone cell. 3. Quercus Bark has sieve tube, companion cell, phloem fiber and sclereid. Sclereids of Quercus bark are the most distinguished characteristics comparing with pinus and populus. The volume percent of sclereids are higher than that of fiber. 4. Rays are 1~3 seriate, and multiseriate ranging with from 15 to 20. 5. Parenchyma cell contains two types, polygonal and druses crystal.