• Journal of the Korean Wood Science and Technology
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• 제40권5호
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• pp.343-351
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• 2012

A large diameter roundwood is an important element of Korean traditional buildings, Hanok, and is hard to be dried without surface cracks. Four different pretreatments, such as pre-cracking, oil heating, kerfing-oil heating and PEG impregnation, were investigated for reducing the surface cracks of large-diameter roundwood specimens during heat treatment. The roundwood specimens of pre-cracking, oil heating and kerfing-oil heating showed surface cracks during pretreatment, but that of PEG impregnation did not. It was confirmed that kerfing reduced the total crack width. Among the four pretreatments and control only the PEG impregnation roundwood specimen had no crack on both outer and inner surfaces after heat treatment. The PEG impregnation specimen shrank only 1.6% in the tangential direction while the pre-cracking did 8.0%.

• Journal of the Korean Wood Science and Technology
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• 제40권5호
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• pp.335-342
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• 2012

To prepare the eco-friendly fire retardant wood, Japanese red pine (Pinus densiflora), Hemlock (Tsuga heterophylla), and Radiata pine (Pinus radiata) were treated with inorganic chemicals, such as sodium silicate, boric acid, ammonium phosphate, and ammonium borate. Different combination and concentration of those chemicals were impregnated by vacuum/pressure treatment methods. The electron-beam treatment was used to increase the chemical penetration into the wood. The fire performance of the fire retardant treated wood was investigated. The penetration of chemicals into the wood was enhanced after electron beam treatment. Ignition time of the treated wood was the most effectively retarded by sodium silicate, ammonium phosphate, and ammonium borate. The most effective chemical combination was found at 50% sodium silicate and 3% ammonium borate, which satisfied flammability criteria for a fire retardant material in the KS F ISO 5660-1 standards.

• Journal of the Korean Wood Science and Technology
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• 제19권4호
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• pp.52-61
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• 1991

In this paper, the difference of the property of absorption and desorption for five species in semi-steady state are studied. The species used are listed in Table 1 and the dimension of specimen was $8\times8{\times}T$(Tangential direction)cm and tested in various conditions. A change of average moisture content with time were measured in each cycles. The results obtained are summarized as follows. When the relative humidity in air was maximum or minimum, the distribution of moisture In wood of all specimens were illustrated by exponential curves of decrease or increased from lace 10 center of wood. From the consideration of coefficient of decrease(C), the amount of moisture change of spruce was larger than the others. The pheonomenon was considered no relation to the specific gravity in air dry, but the wood structures. The velocity of the absorption and desorption for species decreased in the order spruce(Picea sitchensis) neodobam(Fagus crenata), solsong(Tsuga heterophylla), meranti(Shorea sp.) and kaesoo(Cercidiphyllum japoicum). In case of constant temperature and water vapor pressure is changed. the amount of absorbed moisture was larger than that of constant water vapor pressure and temperature vaned. In this fact, it is considered that the property of sorption of wood is strongly influenced by vapor pressure gradient than temperature gradient.

• Journal of the Korean Wood Science and Technology
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• 제29권1호
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• pp.9-15
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• 2001

침엽수 4수종(소나무, 잣나무, 낙엽송, 웨스턴 햄록)의 가열판 압체식 진공건조에서 소요되는 비에너지 곡선은 함수율 감소에 따라 서서히 증가, 거의 일정, 급속 증가 등 3단계의 증가 패턴을 나타내었고, 제재두께별 계산된 비에너지는 3cm 제재 0.483, 5cm 제재 0.649, 7cm 제재 0.814, 9cm 제재 0.977 및 11cm 제재 1.138kWh/kg로서 두께가 증가함에 따라 거의 직선적으로 증가하였고, 강한 건조스케줄을 적용한 비에너지는 약한 건조스케줄의 것보다 적었으며, 가열판 진공건조의 평균 비에너지는 0.712kWh/kg으로서 다른 건조법의 것보다 적었다.

• Journal of the Korean Wood Science and Technology
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• 제29권1호
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• pp.1-8
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• 2001

소나무, 잣나무, 낙엽송과 웨스턴 햄록의 5두께(3, 5, 7, 9 및 11cm) 제재를 3가지 종류의 건조스케줄을 적용한 가열판 압체식 진공건조에서 건조중 함수율, 제재두께와 건조속도의 관계, 제재두께와 건조시간계수의 관계 등을 구명한 결과에서 제재두께 초기함수율 및 건조시간에 따른 건조중 함수율을 추정할 수 있었다. 그리고 함수율 30%에서 15% 범위에서 평균 건조속도는 웨스턴 햄록이 가장 컸고 다음은 소나무, 잣나무, 낙엽송 순위였으며, 제재두께가 증가함에 따라 곡선적으로 감소하였다. 또한 건조시간계수는 제재두께가 증가함에 따라 곡선적으로 증가하였다.

• Journal of the Korean Wood Science and Technology
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• 제12권3호
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• pp.15-24
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• 1984

The $3{\times}3{\times}30\;cm^3$ sized specimens of Douglas-fir(Pseudotsuga menziesii) and western hemlock(Tsuga heterophylla) in this study were soaked in four fire-retardant solutions of ammonium sulfate, monoammonium phosphate, diammonium phosphate, and aluminium chloride for 1, 24, 72, 168, and 336 hours. Subsequently they were air-dried and burned at high temperature of ca. $1,800^{\circ}C$ and for short time of 5 minutes. This study estimated the relationship between the adsorbed chemicals and the residual weight ratio or residual bending strength of these partly burned lumbers. The results were as follows; 1) In average amount of chemical adsorption, diammonium phosphate showed the largest and aluminium chloride the smallest regardless of species but monoammonium phosphate was larger in Douglas-fir than that of western hemlock. 2) The amount of chemical adsorption was larger in western hemlock than Douglas-fir on the whole. 3) The amount of chemical adsorption was increased with the increase of soaking time but the rate of increase began to decrease at 200hrs. 4) Residual weight ratios showed no difference between species but showed differences among the chemicals treated i.e. monoammonium phosphate, diammonium phosphate, ammonium sulfate and aluminium chloride in turn from the largest to the smallest. 5) MOR values showed linear increase with the increase of residual weight ratios but showed no difference in species and chemicals respectively. 6) In the relationship between amount of chemical adsorption and MOR, only diammonium phosphate showed the curve of secondary degree with significance in Douglas-fir. 7) The MOE value of burned Douglas-fir lumber increased and showed significance of 99% as the adsorbed chemical amount increased, but among the chemicals only monoammonium phosphate showed significance. The MOE value of burned western hemlock lumber didn't show significance. 8) In only Douglas-fir, the correlation between adsorbed chemical amount and work to proportional limit showed significance in only monoammonium phosphate. And in both Douglas-fir and western hemlock, the correlation between adsorbed chemicals and work to maximum load showed significance in monoammonium phosphate.

• Journal of the Korean Wood Science and Technology
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• 제41권3호
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• pp.173-180
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• 2013

PEG 주입을 통해 열처리 중 목재의 균열을 방지하기 위한 연구에 필요한 기초자료를 제공하기 위해 본 연구가 수행되었다. 국내에서 사용되는 대표적인 침엽수 세 수종의 소시편을 이용하여 PEG 분자량에 따른 침투 속도와 잔류량, 열처리 후 잔류량, 평형함수율 등을 조사하였다. PEG400의 평균 잔류량은 수종별 기본밀도에 반비례하였으며 다른 분자량 PEG에서도 비슷한 경향을 나타냈다. 한 수종 내에서는 PEG 분자량이 클수록 잔류 PEG 양이 감소하는 경향이 뚜렷하다. PEG 주입에 의해 함수율이 2% 내에서 증가하거나 감소하였으며, 시편의 평균 기본밀도는 최고 16.8%까지 증가하였다. 열처리에 의한 중량감소율은 PEG400 시편이 PEG600, PEG1000 보다 컸다. 낮은 분자량의 PEG가 더 많이 용출되었다고 볼 수 있다. 평형함수율은 상대습도가 낮을 때(32%RH) 세 수종 모두 PEG 주입 시편과 무처리 시편의 차이가 없었으나, 상대습도가 증가할수록 PEG 주입 시편이 무처리 시편보다 높게 나타났다.