• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.74-84
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• 1995

Eight types of thin composite panels were manufactured by press-lam and mat-forming process applied to optimum manufacturing condition, studied in former first research by author (1995). They were tested and compared with control boards on dimensional stability, internal bond strength, tensile strength, Screw withdrawal strength, and bending properties. These thin composite panels manufactured by mat-forming process were generally superior to those by press-lam in dimensional stability and mechanical properties. In the dimensional stability and mechanical properties of thin composite panels manufactured by mat-forming process, the thin composite panels (A and E type) composed of particle or sawdust core and veneer face with polyethylene film, were as good as those of common plywood (control board). Internal bond strength showed highest value in the thin composite panel(D type) which composed of particle core and polypropylene screen face with polyethylene film. The thin composite panels(G and H type) composed of sawdust or particle core and polypropylene screen face with polyethylene film by press-lam and mat-forming process, showed most highest value in dimensional stability and water absorption.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.18-26
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• 1995

국내 합판 산업계는 오랫동안 남양재 활엽수를 주로 사용하여 왔으나, 환경 보존적인 측면에서 열대재의 벌채를 규제하는 등 여러 요인으로 인하여 합판용 원목의 수입이 어려워지고 있다. 이에 대응하기 위하여 합판용 원목을 침엽수재로 대체할 필요가 있으며, 침엽수 합판 제조를 위한 기초 자료를 제공하기 위하여 본 연구를 수행하였다. 공시 수종은 국내에서 조림한 낙엽송과 시베리아산 낙엽송 및 뉴질랜드산 라디에타 소나무였으며, 공시원목으로부터 얻어진 단판의 품질과 이들 단판으로 제조한 합판의 접착력과 휨강도를 조사하였다. 이면 할렬실험에서 시베리아산 낙엽송은 다른 수종에 비해 할렬 밀도가 낮게 나타났다. 단판 품질은 접착력 및 휨강도에 거의 영향을 미치지 않았으나 합판의 휨강도에서는 심재와 변재에 따른 차이가 있음을 알 수 있었다. 이는 합판제조사 심재와 변재를 구별하여 사용할 필요가 있었다. 라디에타 소나무의 변재부로 만든 합판 MOR은 다른 수종에 비해 우수하게 나타났다. 접착력 실험에 있어서는 페놀 접착제를 사용하여 만들어진 합판만이 구조용으로써 사용할 수 있음을 알았다. 목파율은 동일 수종 합판에서는 라디에타 소나무 구성이 가장 높게 나타났으며, 이수종(異樹種) 합판에서는 표판을 국산 낙엽송, 심판을 라디에타 소나무를 사용하여 만든 합판에서 가장 높게 나타났다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.47-50
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• 2008

This study analyzed the effect of increasing the number of times using aluminum form to the surface quality of concrete through small sized test, and the result was summarized as following. At the early stage, there was no remarkable change between aluminum and coated plywood form, and the surface quality of concrete both forms slightly declined corresponding with increasing the number of times using.As void on the surface corresponding to the number of times, the voids ranged 0.1~1mm were increased corresponding to increasing the number of times using forms, and the other range voids were also increased according to increasing the number of times using forms. It was confirmed that the surface of concrete was damaged gradually. For comparison with aluminum and coated plywood form though this experimental results, there might be no difference, if release agent was used properly.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.54-57
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• 2007

Urea-formaldehyde (UF) resin was formulated similarly to plywood resin in the laboratory. The synthesized UF resin adhesive was mixed with extender, filler and acid catalyst. The mixture contained 56.1% total solids and 43.9% water. The mixes was used to bond five Com-Ply types using Korean wood species. The Com-Ply made were tested for shear strength and wood failure according to KS F 3101 ordinary plywood as well as for bending strength per KS F 3104 particleboard. The performance test results showed good strength properties for all Com-Ply types made in this study. This result represented that the UF resin adhesive mix was adequate for bonding Com-Ply with domestic wood species.

• Applied Biological Chemistry
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• v.39 no.2
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• pp.123-126
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• 1996

Simple and rapid method of purification of plasma proteins from bloods of slaughtered animals was developed and the proteins were applied to plywood products as a blood 히ue to utilize waste materials. Plasma protein was obtained by adding 2% trichloroacetic acid (TCA) or 0.6 N HCI as optimal concentration to the supernatant, after centrifugation of bloods. Molecular properties of beef and pig plasma proteins were examined on SDS-PAGE. Application of blood glue to plywood was quite satisfactory compared to the synthetic amino resin by tensile-shear test for the strength of adhesive bonding.

• Journal of the Korea Furniture Society
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• v.14 no.2
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• pp.21-29
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• 2003

This study was carried out to investigate characteristics of plywood overlaid with softwood veneers densified by resin impregnation and compression. The resin impregnability of Korean pine veneer under atmospheric pressure soaking was greater than that of larch, and impregnability of melamine resin was slightly greater than phenolic resin. It was suggested that resin impregnation ratio was affected by density and thickness of veneer. The largest melamine resin impregnation ratio of 50.7% was obtained with 1.26mm thick Korean pine veneer, and the lowest phenolic resin impregnation ratio of 11.7% with 3.41mm thick larch veneer. Therefore, it was suggested that the vacuum-pres sure-soak treatment is required at thick larch veneer. In densifying resin-impregnated veneers, densification ratio from 13.4 to 31.2% was obtained by high pressure from 15.6 to $20.8kgf/cm^2$. Impregnation of melamine resin also showed relatively greater at densification than that of phenolic resin. So it showed the degree of densification of about 20% or greater. It was seemed that adhesive bonding strength of plywood(base panel) which was directly pressed and overlaid with resin-impregnated veneer was affected by resin tackiness after resin impregnation followed by semi-drying. In laboratory scale, melamine resin impregnation was more favorable for the development of adhesive bonding strength owing to moisture control.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1123-1131
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• 2005

The floor material is known as the most influential emission source of the residential building, because most floor material is made of wood compound and adhesive like a plywood flooring. Moreover, floor heating system keeps the inside temperature of the material high. As the emission of hazardous chemical compound from the construction material is influenced by many factors, it is necessary to analyze the emission characteristics of the floor material to improve IAQ. In this study, numerical analysis is performed to investigate the emission characteristics of the floor material affected by several factors such as temperature, air exchange rate, initial concentration, and internal diffusion coefficient. A simulation program is also written based on the mass transfer theory. The simulation results show that there is some level of difference on the TVOC concentration when each of the factors is variable.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.33-39
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• 2019

The square timbers of larch having cross section of $90mm{\times}90mm$ were glued laterally to be formed $1,200mm{\times}2,400mm$ panels which were used as cores for CLT wall panels. Then, structural plywood panels having size of $1,200mm{\times}2,400mm$ were used as cross band covering the small square timber cores to manufacture CLT wall panels. The sound absorption rate of CLT wall panels and polyester board attached CLT wall panels were investigated. The mean sound absorption coefficients of the former and the latter in the frequency range of 100-6400 Hz were 0.21 and 0.74, respectively. The noise reduction coefficients (NRC) of those were 0.21 and 0.40, respectively. Also, the mean sound transmission loss of CLT wood panel in the frequency range of 50-1600 Hz was 45.12 dB and that value at the frequency of 500 Hz was 42.49 dB. It was suggested that the polyester board attached CLT wall panels could be used as housing wall because of its high sound absorption rate and high sound transmission loss.

• Journal of Korean Society of Forest Science
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• v.51 no.1
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• pp.41-50
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• 1981

The purpose of this study was to evaluate the substitutional possibility of new extender instead of wheat flour, which is extending for plywood adhesives in Korea. As the extending materials corn stalk, pine bark, Pitch and Korean pine leaves, wheat, or wood flour were selected and prepared for the extending powders, dried at $103{\pm}2^{\circ}C$ during 24 hours in the drying oven, followed by being pulverized into 60-100 mesh powder. The extenders were mixed with urea formaldehyde resin in the ratio of 5, 10, 15 or 20%. After plywoods were manufactured by the above extended ratios, dry and wet shear strength and wood failures were analyzed and discussed. The results at the study may be summarized as follows ; 1. In urea formaldehyde resin dry shear strength in plywood extended by wheat flour showed the highest value. 2. Among the extenders in 10 and 20% extension of urea formaldehyde resin wet shear strength of wood flour was higher than that of wheat powder. They had no significant difference statistically. 3. Among the extenders of 5% extension of water soluble phenol formaldehyde resin dry shear strength of plywood extended by Korean pine leaf powder showed the highest value, while wheat powder showed the highest value among 10, 15 and 20% extentions. 4. In water soluble phenol formaldehyde resin the best results of wet shear strength showed in wheat powder. 5. Among the extenders in 15 and 20% extension of water soluble phenol formaldehyde resin, dry and wet shear strength in plywood of corn stalk powder were the highest value next to wheat powder.