• Journal of the Korean Wood Science and Technology
• /
• 제44권5호
• /
• pp.726-735
• /
• 2016

본 연구는 두께 15 cm와 18 cm 크기 Douglas-fir, Hemlock, Radiata pine 정각재의 고온건조 특성을 평가하기 위해 수행되었다. 수종에 따른 최종함수율은 시험재의 두께에 관계없이 Radiata pine, Douglas-fir, Hemlock 순으로 Radiata pine에서 가장 낮았으며, 배할처리를 하였을 때 무처리재보다 낮은 함수율을 나타내었다. Radiata pine과 Hemlock의 경우 배할처리를 하였을 때 함수율과 뒤틀림 발생을 감소시키는 효과가 있는 것으로 나타났다. Douglas-fir는 수를 포함하지 않는 정목형태로 가공될 때 건조결함의 감소가 가능하였다.

• 농업과학연구
• /
• 제21권2호
• /
• pp.103-110
• /
• 1994

국내시장(國內市場)에 안정적(安定的)인 공급(供給)이 가능한 온대(溫帶) 침엽수재(針葉樹材)를 남양(南洋) 활엽수재(闊葉樹材) 문틀재의 대체재(代替材)로 사용하기 위해 K등급(等級) 북미침엽수재(北美針葉樹材)의 옹이 분포도와 가공(加工) 후(後) 틀어짐 정도, 그리고 생산 수율(收率)과 단가(單價)을 조사하였다. D-fir와 W.hemlock를 문틀가공(加工) 전에 옹이 크기와 분포(分布)에 따라 등급판정(等級判定)한 결과(結果), 기둥재로 쓸 있는 A급소재(級素材)의 비율은 D-fir가 36.4%, W.hemlock가 24.3%으로 D-fir가 높았으나 이는 두 수종의 등급판정(等級判定) 기준이 다른 때문이며 재색(材色)으로 보나 재질(材質)로 보나 W.hemlock이 문틀재로 쓰기에 더 적합하였다. 문틀당 평균(平均) 옹이수는 D-fir와 W.hemlock이 각각 7.2개와 3.4개이며 W.hemlock은 8개이상(以上) 옹이를 가진 문틀재가 없는 반면, D-fir은 8개이상(以上) 옹이를 가진 문틀재가 전체의 절반이나 되었다. 한편 D-fir는 옹이직경(直徑) 5cm이상(以上)이 11%인데 반해 V.hemlock은 35%였다. 따라서 D-fir는 작은 옹이가 많이 있으나 W.hemlock은 큰 옹이가 비교적 적게 분포됨을 알 수 있다. 틀어짐 측정장치(測定裝置)로 잰 D-fir의 최대최소(最大最小) 변형차(變形差)는 D-fir의 경우 문틀재에 따라 0.5부터 9.5mm까지 비교적 고르게 분포되어있는 반면 W.hemlock은 거의 대부분이 4.5mm이하(以下)에 몰려 있다. 6mm변형(變形)을 문틀재로 쓸 수 있는 한계점으로 볼 때 이 기준(基準)을 넘는 문틀재는 D-fir가 전체 21개 중 6개로 30%에 달하나, W.hemlock은 전체 25개 중 단 한 개만 있었다. 문틀재의 가공단계별(加工段階別) 원가(原價)를 산출(算出)한 결과(結果), D-fir는 1,993 원/재(才)였으며 W.hemlock는 1,697 원/재(才)였다. 이 차이(差異)는 주로 제재수율(製材收率)차에 기인한 것으로 보인다. 따라서 온대(溫帶) 침엽수재(針葉樹材) 문틀재, 특히 W.hemlock은 틀어짐이나 수율(收率), 가격에 있어 남양재(南洋材)와 충분한 경쟁력을 가지고 있으나 옹이가 없는 남양재(南洋材)에 길들여져 있는 소비자의 취향이 침엽수(針葉樹) 문틀재 시장(市場) 확장(擴張)에 중요(重要)한 요인(要因)으로 작용(作用)할 것이다.

• Journal of the Korean Wood Science and Technology
• /
• 제16권4호
• /
• 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 Wood Science and Technology
• /
• 제26권4호
• /
• pp.34-42
• /
• 1998

Three hardwood (ash, alder and black locust) and three softwood (Japanese red pine, radiata pine and Western hemlock) specimens were dried in microwave(MlW) oven and their drying rates were obtained. Their specific permeabilities were also measured by using a modified liquid permeability measuring device. The correlation between the M/W drying rates and permeabilities of six species were statistically analyzed. It was revealed that within a species there is a logarithmic relationship between the M/W drying rates and average moisture contents and that among species there is a linear relationship between the M/W maximum drying rates and the average specific permeabilities. A exception was Western hemlock, which was of low permeability and of high drying rate. A Me-time equation, which showed a good agreement with the actual data, was derived. Thus using this equation the moisture contents of wood and the drying end points of M/W drying could be predicted. Infrared images of the thermal distribution in wood were illustrated.

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

• 생물환경조절학회지
• /
• 제15권1호
• /
• pp.100-106
• /
• 2006

A hypertonic solution of sorbitol was used to precondition Douglas-fir and Western hemlock plug seedlings to improve desiccation resistance. Seedlings were preconditioned by soaking their root balls in water, -0.75 or -1.50 MPa sorbitol solution for 22 hr, and then exposed to desiccation conditions for 8 days. During the desiccation period, a transpirational water loss was significantly reduced by the sorbitol preconditioning, with its effect positively depending on concentration. This preconditioning-induced reduction in water loss was mainly caused by the decline in needle stomatal conductance. Sorbitol-induced stomatal control was more closely associated with reduction in plant water potential, rather than increase in abscisic acid concentrations. After rehydration of stressed-plants, most of the preconditioned seedlings with sorbitol were survived, while only 35% of Douglas-fir and 28% of Western hemlock seedlings treated with water were alive. The post-growth was significantly greater in the preconditioned seedlings than only water-treated seedlings. These results suggested that the earlier stomatal control with sorbitol-facilitated preconditioning could play a role in improving desiccation resistance of evergreen woody plants at transplanting in the field where water supply is limited or dry conditions are prevailing.

• Journal of the Korean Wood Science and Technology
• /
• 제35권5호
• /
• pp.38-45
• /
• 2007

Flakeboards made from ring- and drum-cut flakes of Douglas-fir, hemlock, red lauan and kapur using two kinds of resin levels were evaluated for the selected properties according to flake thickness. The pH and buffering capacity of four species were determined. Those of kapur were extremely different from the other three species. These pH and buffering capacity values result in the poor internal bond strength of kapur flakeboard. The internal bond strength was affected significantly by flake thickness, resin content and species. MOR and MOE in bending strength were maximized at medium drum-cut flake thickness. Screw holding strength was not consistent for flake thickness, but it was influenced by species. Thickness swelling and water absorption of Douglas-fir and hemlock flakeboard were minimized at medium drum-cut flake thickness.

• Journal of the Korean Wood Science and Technology
• /
• 제37권5호
• /
• pp.459-464
• /
• 2009

This study was conducted to find the relationship between the moisture content and basic density of green lumber and the final moisture content of kiln dried lumber. The possibility of using a ultrasonic nondestructive testing technology was investigated. Four matched 2-foot long boards were kiln-dried for 12, 24, 36 and 48 hours. Twenty three slices were cut to examine the distribution of moisture content along the length. It was revealed that the green weight was a better estimator of the final moisture content of the kiln-dried board than the green moisture content. The standard deviations of the moisture contents of the slices were not correlated with the final moisture contents of the kiln-dried boards. The two ultrasonic devices used for this study were apparently good tools for NDT.

• Journal of the Korean Wood Science and Technology
• /
• 제29권3호
• /
• pp.27-35
• /
• 2001

Four different sources of wood-fibers from Eucalyptus, Italian poplar, hemlock, and mixed species fibers were used to study the influence of their fiber characteristics on the performance of medium density fiberboard (MDF) panels bonded with both urea-formaldehyde (UF) and phenol-formaldehyde (PF) adhesives. Included fiber characteristics were fiber length, size distribution, bulk density, and acidity. Physical and mechanical properties of MDF panels manufactured by dry process using these different fibers were determined for the comparison of board performance. Two hardwood species had a large fraction of short fibers resulting in a higher bulk density while very long hemlock fibers had lower bulk density. Fiber acidity was revealed to strongly affect the internal bond (IB) strength of MDF panels bonded with UF resins. MDF panels made from mixed species fibers showed highest IB strength of all panels prepared. UF-bonded MDF panels showed poor dimensional stability. In conclusion, the present study showed that wood-fiber characteristics such as fiber length, bulk density, and acidity affect the performance of MDF boards, and also suggested that fiber characteristics be considered for MDF panel manufacture.

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