• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.254-262
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• 2003

In this study, acoustic emission (AE) signals due to surface cracking and moisture movement in the flat-sawn boards of oak (Quercus Variablilis) during drying under the ambient conditions were analyzed and classified using the principal component analysis. The AE signals corresponding to surface cracking showed higher in peak amplitude and peak frequency, and shorter in rise time than those corresponding to moisture movement. To reduce the multicollinearity among AE features and to extract the significant AE parameters, correlation analysis was performed. Over 99% of the variance of AE parameters could be accounted for by the first to the fourth principal components. The classification feasibility and success rate were investigated in terms of two statistical classifiers having six independent variables (AE parameters) and six principal components. As a result, the statistical classifier having AE parameters showed the success rate of 70.0%. The statistical classifier having principal components showed the success rate of 87.5% which was considerably than that of the statistical classifier having AE parameters.

• Journal of the Korean Wood Science and Technology
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• v.4 no.1
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• pp.15-20
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• 1976

This is the abstract of the study on the check by static driving nail in Pinus koraiensis Sieb. et Zucc., Abies holophylla Maximowicz, and Larix leptolepis Gordon Pinet. which are commercial woods and main forestation species in Korea. The static driving resistance of nail is decresed straightly and the surface and back check's length and width were increased in proportion to increase of the moisture content, but the surface check length and width were over twice as large as the back check, also the check were happened in order of Pinus koraiensis Sieb. et Zucc., Abies holophylla Maximowicz., and Larix leptolepis Gordon Pinet. As the driving nail speed was increased, surface check length and width were increased and the back check was over twice as large as the surface check.

• Journal of Forest and Environmental Science
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• v.12 no.1
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• pp.1-12
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• 1996

This study was carried out to estimate drying schedule of Fagaceae four species grown in Kangwon-Do by oven-drying at $100^{\circ}C$ which aimed to elucidate the characteristics such as current moisture content, drying process, initial check, collapse and internal check during drying following each board thickness (1.5cm, 2.5cm, 3.5cm, 4.5cm). The results were as follows; Current moisture content of each board showed a rapid drying curve with the high initial moisture content of board. With the high initial moisture content, the incease of board thickness and the slowness of changing rate of moisture content, species took long to do drying. Also, the initial conditions of drying had to be mild condition with the increase of board thickness.

• Journal of the Korean Wood Science and Technology
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• v.17 no.1
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• pp.3-11
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• 1989

This study was carried out to investigate the physical and mechanical properties. durability of adhesive bond and paint film for the basic data which were required to determine the suitability as a raw material for furniture the laminated veneer lumber (LVL) with pitch pine (Pinus rigida Mill). The results obtained were as follows; 1) The proper pressing time for making the LVL was over 45 second per milimeter of LVL thickness. 2) The bending strength of the LVL was lower than that of the solid wood but the compressive strength of the LVL was similar to that of the solid wood. The strength increased with the decrease of veneer thickness. 3) The impact bending absorbed energy of the LVL was 0 to 0.3 kg.m/$cm^2$ in the direction of parallel to the grain. The energy of the LVL was lower than that of the solid wood (0.68 kg.m/$cm^2$). 4) In warm water soaking and cold-dry tests, delamination of adhered layers surface crack, swelling, and color change were not found when the hot pressing time was over 45 second per milimeter of LVL thickness. As a result of soak under vacuum test shrinkage in the direction of parallel to the grain was about -1.0 percent and. was about 3.0 percent in the direction of the perpendicular to the grain. 6) The film cacks on the LVL's surface after the wet and cold-dry test were not found at all. 7) In the use of the LVL for interior decoration it was considered that the surface of the LVL be overlaid crossly with fancy veneers of birch and paulownia, etc. This cross overlayirg methods have resulted in few cracks on the fancy veneer.

• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.17-25
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• 1990

양표면은 무결점재를, 가운데 단판은 경사목리 및 목리방향의 할열을 가진 단판을 사용하여 제조한 3매 단판 적충재에 있어서 목리방향과 할열의 인장탄성계수 및 인장강도에 미치는 영향에 대하여 조사하였다. 또한, 비파괴 시험 방법인 응력파 실험에 의하여 각단판의 탄성계수를 측정하고, 이들 단판의 탄성계수로부터 단판적층재의 탄성계수를 예측하여 실측치와 비교하였다. 응력파에 의해 예측된 탄성계수는 인장실험으로부터 얻어진 결과와 거의 일치하였으며 인장탄성계수와 인장강도간에도 높은 상관관계를 나타내었다($r^2$=0.681). 인장강도에 있어서는 가운데 단판 할열의 영향은 나타나지 않았으나 목리의 경우 경사각이 증가함에 따라 인장강도가 감소하는 경향을 나타내었다.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11a
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• pp.72-80
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• 1999

친수성의 도공층을 갖고 있는 컬러 잉크제트 용지의 특성을 동적주사 흡액측정, 망점의 화상해석 및 도공층 표면을 주사 전자현미경(SEM)으로 관찰하여 검토하였다. 비잉크제트 용지와 도공지에 비하여 잉크제트 용지는 단시간 동안에 현저한 표면 흡액특성을 나타내었지만 그 특성은 제품에 따라 다르게 나타났다. 망점 특성으로부터 평가한 잉크 방울의 흡수시간은 망점의 면적과는 상관관계를 나타내진 않았으나 진원도와는 부의 상관관계를 나타냈다. 즉 빠른흡액특성은 원형의 망점을 형성하는데 유효하였다. 광택 처리제품과 광택처리를 하지 않은 제품을 비교할 경우 광택처리 제품의 진원도가 낮게 나타났는데 이것은 주사전자현미경의 관찰 결과로부터 도공층을 칼렌더 처리할 때 발생하는 할열 때문인 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
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• v.14 no.3
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• pp.3-15
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• 1986

This study was carried out to investigate the drying rate and drying defects of Populus euramericana using the SDR (Saw-Dry-Rip) process. Flitches for SDR process were rough edged for compact kiln stacking, and then kiln-dried to 10 percent moisture content with dimensions in the same run, using the kiln-drying schedule ($T_8-F_4$) recommended by Rasmussen. The results obtained were as follows: 1. Drying rate of dimensions was slower than that of flitches. 2. Final moisture content and moisture distribution of dimensions were lower than those of flitches. 3. Average bowing, cupping, crooking, and twisting were reduced 20 percent, 25 percent, 54.9 percent, and 13.4 percent by SDR process respectively. 4. Bowing and cupping were more severe in dimensions from the area near the pith than in those from the area near the bark, and for crooking and twisting the reverse was true. 5. Surface checking of dimensions developed less than that of flitches and end checking of dimensions was similar to that of flitches. 6. Honeycomb, thickness shrinkage, and collapse of dimensions were similar to those of flitches. 7. The degree of casehardening of dimensions was higher than that of flitches.

• Journal of the Korean Wood Science and Technology
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• v.18 no.3
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• pp.34-41
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• 1990

본 연구는 CCA로 방부(防腐)처리된 Lodgepole pine 각재(角材)의 재건조(再乾燥)시 고온건조법(高溫乾燥法)의 적용이 건조속도(乾燥速度) 및 건조결함(乾燥缺陷)의 발생에 어떻게 영향하는가를 고찰하고자 수행되었다. 고온건조시 건조속도는 통당(通常) 열기건조(熱氣乾燥)시보다 약(約) 2.5배 증가되었으며, 방부처리재의 재건조 속도는 처리전(前)의 전건조속도보다 약간 감소됨을 보였다. 표면할열(表面割裂)의 발생정도(程度)은 전건조시의 경우, 고온건조시 보다 심(甚)하였으나 재건조시에는 건조방법간에 큰 차이가 없었다. 방부제의 침투(浸透)를 도모(圖謀)하기 위하여 자상(自傷)처리(Incising)된 각재의 경우에는 재건조시 절개부(切開部)의 연장(延長)에 의해 할렬의 정도가 증가됨을 보였다. 뒤틀림(Warping)의 발생정도는 고온건조시가 통상 열기건조에 비해 심하지 않았으며, 전(全) 건조과정을 통하여 발생된 뒤틀림은 WWPA가 정(定)해놓은 Lodgepole pine 2등급(等級)(No. 2 grade)의 뒤틀림 허용치(許容値)의 범위내(範圍內)에 있음을 보였다. 결론적(結論的)으로, 고온건조시 증가되는 건조속도와 건조재의 질(質)에 큰 영향을 주지않는 범위내에서 발생되는 건조결함을 고려할 때, Lodgepole pine의 전건조및 CCA 처리후 재건조를 위해 큰 문제없이 고온건조법이 적용될 수 있음을 보였다.

• Journal of the Korean Wood Science and Technology
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• v.34 no.1
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• pp.7-14
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• 2006

Three-dimensional distribution and variation of moisture content of boxed-heart square timber of Pinus densiflora was investigated to find the safe and rapid drying methods. As results, microwave-drying method could dry the boxed-heart square timber with sectional dimension of $150{\times}150mm$ under 10% moisture content (MC) within 72 hours with less surface checks, compared with hot-air drying. In case of microwave drying, the MC distribution during drying had a close relation with the initial MC distribution. In case of hot air drying, however, it was independent on the intial one except for the intial drying stage.

• Journal of the Korean Wood Science and Technology
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• v.13 no.2
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• pp.3-13
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• 1985

This study was carried out to investigate the effects of presteaming on the drying rate and drying defects of 3 cm - thick Quercus acutissima. Specimens for presteaming were steamed green at $100^{\circ}C$ for 4 hours and then kiln-dried to 10 percent moisture, content with controls, using the kiln-drying schedule ($T_4-C_2$) recommended by Rasmussen. The results obtained were as follows: 1. Presteaming reduced drying time approximately 18 percent from 70 to 10 percent moisture content. 2. The effect of presteaming on surface checking was not significant. 3. Presteamed specimens showed the reduction in end checking compared with controls. 4. Percents of boards with collapse, cupping, and honeycomb of presteamed specimens were slightly lower than those of controls. 5. Dry lumber grade of presteamed specimens was better than that of controls. Percent of first grade boards of presteamed specimens was 20 percent higher than that of controls and percents of second and third grade boards of presteamed specimens were 15 and 5 percent lower than those of controls, respectively.