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정희석,찰리코즈리크 한국목재공학회 1983 목재공학 Vol.11 No.5
Press-drying was used an 0.25 inch-and 0.50 inch-thick flatsawn board of Oregon white oak heartwood at platen temperature of constant boiling point (212 F), constant lower plateau temperature (244 F) and combination of boiling point for 40 minutes and lower plateau temperature later by using platen pressure of 35 pounds per square inch to explore the effect of temperature step-press drying on drying rate and honeycombing. The results of study were same as follows. 1. Press-drying of constant boiling point increased drying times and decreased honeycombing considerably for boards of bath thicknesses. 2. Press-drying of constant plateau temperature reduced drying times but showed severe honeycombing for boards of both thicknesses. 3. Press-drying of temperature step-press drying decreased drying times and honeycombing far 0.25 inch thick boards the same as press-drying of constant lower plateau temperature, but not decreased drying times and honey-combing for 0.50 inch-thick boards.
증기압 (蒸氣壓) 경사(傾斜)가 은수원 사시나무 변재의 횡단방향 확산에 미치는 영향
정희석,박정환 한국목재공학회 1984 목재공학 Vol.12 No.5
This study was carried out to investigate the effects of vapor pressure gradients on moisture diffusion into transverse direction of hybrid aspen (Poplus alba x glandulosa) sapwood. Saturated salts solutions and vapor meter cup were used to measure the rate of adsorption and vapor meter cup were used to measure the rate of adsorption and diffusion coefficients. The oven dried specimens which were 0.5 cm thick, 2.5 and 5.0 cm wide were used also to measure the rate of adsorption and diffusion coefficients, respectively. The results obtained were summarized as follows 1. The rates of adsorption were greater in high relative humidity conditions than in low relative humidity conditions. The rates of adsorption were increased rapidly in early stage of adsorption, however, the rates of tire increase of adsorption decreased after 24 hr. And, there were parabolic relationship between the rates of adsorption and adsorption time. 2. The diffusion coefficients into transverse directions were increased in parabolic shape with the increase of moisture gradients and the effects of moisture gradients were mote pronounced for radial than for tangential direction. 3. In low moisture gradients range, there was no significance in difference of diffusion coefficients between the radial and tangential direction, but in high moisture gradients range, 11.05 and 17.63%, diffusion coefficient was 1.5 times greater than that of tangential direction.
전평삭처리(前平削處理)가 물참나무의 건조속도와 건조결함에 미치는 영향
정희석,한규성 한국목재공학회 1986 목재공학 Vol.14 No.4
To investigate the effect of presurfacing, both 25㎜ rough and presurfaced oak boards (Quercus grosseserrata Bl.) were dried in the same dry kiln condition, Drying curves* drying strains and drying defects of rough and presurfaced boards were compared. The results obatained are as follows. 1. Average drying rate of rough and presurfaced boards from green to 10% M.C. was 0.276%/hr. and 0.284%/hr., respectively. 2. At the early stage of drying, in ease of rough boards, maximum tensile strain of outer slices was -24.2×10^(-4)㎜/㎜ and maximum compressive strain of innermost slices was 13.0×10^(-4)㎜/㎜, and in case of presurfaced hoards, maximum tensile strain of outer slices was -14.5×10^(-4)㎜/㎜ and maximum compressive strain of innermost slices was 28.1×10^(-4)㎜/㎜. And in both cases, stress reversal occurred at about 40%, M.C.. 3. Maximum surface checking appeared at about 40% M.C.. Of the 10 rough boards, 6 hoards contained surface checks, but presurfaced boards did not contained surface checks after drying. And the results of end checking were similar to those of surface checking. But, honeycomb was not found in both cases. 4. Board shrinkage, warp and casehardening of presurfaced boards mere similar to those of rough boards. F3ut, collapse of prsurfaced boards was less than that of rough boards.
정희석,박문재 한국목재공학회 1995 목재공학 Vol.23 No.1
高度의 엔지니어링 構造物로 경제성이 높은 輕骨 木造 트러스에 사용될 수 있는 소나무 (Pinus densiflora) 材에 적용한 20게이지 아연도금鋼 플레이트 接合部의 荷重-變位 特性을 평가하기 위하여 Foschi 모형을 사용하여 모형 母數를 산출하고 실험치와 계산치를 비교·분석하였다. 接合部의 荷重-變位 曲線은 비선형 특성을 나타내었다. 접합부의 하중성능 및 剛性은 플레이트 및 목리에 평행한 형태에서 최대치를 나타내었고, 플레이트에 직각이고 木理에 평행한 형태로부터 플레이트에 평행이고 목리에 직각인 형태순으로 감소하다 플레이트 및 목리에 직각인 형태에서 최소치를 나타내었다. 3-母數 비선형 모형으로 예측된 스테인레스 鋼 및 아연도금 鋼 플레이트 접합부의 하중-변위 특성에 대한 계산치는 실험치와 잘 일치하였다.