• 한국가구학회지
• /
• 제10권2호
• /
• pp.55-61
• /
• 1999

This research was carried out to investigate the fundamental properties such as the structure of annual ring, density distribution, compressive strength with parallel to grain, relative crystallinity, and microfibril angle of Gumgangsong(Pinus densoflora for. erecta Uyeki). The wood specimens, Gumgangsong and Sonamu(Pinus densiflora S. et Z.), for this experiment were prepared at Ulijingoon Sokwangri and Kyungpook university's forest in Kyungpook province, respectively. Average annual ring width is $2.0mm{\pm}0.3$ in heartwood of Gumgangsong. The respectively of heart wood was over 60 percent in Gumgangsong and 20~50 percent in Sonamu. Heartwood density were ranged from 0.5 to $0.8{\;}g/cm^3$ in Gumgangsong and from 0.4 to $0.5{\;}g/cm^3$ in sonamu. Compressive strength in Gumgangsong and Sonamu was about $30{\pm}5MPa$ and $25{\pm}5MPa$, resepectively. But the relative crystallinity and microfibril angle of two species were not different clearly. From these results of Gumgangsong and Sonamu, therefore, it was considered the main difference factors for both species were annual ring width and heartwood percentage.

• Journal of the Korean Wood Science and Technology
• /
• 제48권4호
• /
• pp.569-576
• /
• 2020

This study investigated the characteristics of microfibril angle(MFA) in order to see if there was any difference in pine tree lumber quality among the three mountain areas surrounding the Taebaek Mountains in Korea - Yeongdong (Goseong-gun), Yeongseo (Hongcheon-gun) and Yeongnam (Bonghwa-gun). Pine trees of each mountain area were divided into earlywood and latewood in relation to heartwood part (1959 ~ 1961, 3 annual rings) and sapwood part (2002 ~ 2004, 3annual rings), and measured at tangential section. The microfibril angle showed significant differences between mountain areas. In general, Goseong Mountain was found to have 37.35°, followed by Hongcheon Mountain 32.42° and Bonghwa Mountain 25.75°, in order. The sapwood part had larger angle than heartwood part; and earlywood, than latewood. Variation within a single annual ring tended to be smaller from earlywood toward latewood.

• Journal of the Korean Wood Science and Technology
• /
• 제21권2호
• /
• pp.73-80
• /
• 1993

Pinus koraiensis is one of the most important reforestation species which had widely been planted around the country. Therefore, there are great research needs on the fundamental properties of wood to extend the frequency of uses and adequate availabilities. Research results on the characteristics of anatomical wood properties and changes are summarized as follows: 1. At a horizontal direction of tree trunk, the tracheid length at outer wood gradually becomes shorter as it reaches to pith. The tracheid length having between 32 and 42 annual rings showed over 2.5 times longer than that of pith, and also its length increases from the bottom to the top of the stem. 2. The tracheid diameters in latewood showed a little fluctuations, and the shortest near to the pith in earlywood. The tracheid diameters in earlywood are more than 2 times those of latewood, and the differences between the mature and juvenile wood in earlywood are less than 10${\mu}m$. 3. The tracheid wall thickness in early wood showed a little fluctuations. On the contrary, tracheid wall thickness in latewood rapidly increases from the pith to the bark. The tracheid wall of mature wood showed 10 to 20% thicker than that of juvenile wood. 4. The fibril angle at the secondary walls of tracheid within an annual ring showed higher degree in earlywood than that of latewood. The highest tracheid fibril angle was observed at around the pith of both earlywood and latewood. Then, fibril angle slowly decreased toward outer wood, and was stabilized after 15 years. 5. Structural boundaries between mature and juvenile wood from Pinus koraiensis are divided by 13 to 19 annual ring and distance of 5 to 8cm from the pith.

• Journal of the Korean Wood Science and Technology
• /
• 제42권3호
• /
• pp.290-300
• /
• 2014

이 연구에서는 가문비나무를 이용하여 직교형적층재를 제작하였고, 섬유직각방향라미나의 연륜경사각이 직교형적층재의 정적 휨 강도성능에 미치는 영향을 조사하였다. 3층 모두가 섬유직각방향라미나로 구성된 평행형적층재($P_{\bot}$ 타입)의 휨 강도성능은 연륜경사각 $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$의 순이었고, 연륜경사각 $45^{\circ}$에서 휨 탄성계수는 0.0989 GPa, 휨 강도는 3.25 MPa로 가장 적은 값을 나타내었다. $P_{\bot}$ 타입의 중층에 섬유방향라미나를 배열하는 것에 의해 휨 강도성능은 현저히 향상되었다. 표층이 섬유직각방향라미나로 구성된 직교형적층재($C_{\bot}$ 타입)의 경우, 휨 강도성능은 연륜경사각 $90^{\circ}$ > $0^{\circ}$ > $45^{\circ}$의 순이었으나, 연륜경사각에 의한 차이는 평행형적층재에 비해 감소하였다. 중층에 섬유직각방향라미나를 배열한 직교형적층재($C_{\parallel}$ 타입)의 경우, 휨 강도성능은 $P_{\bot}$ 타입 및 $C_{\bot}$ 타입과 다르게 $45^{\circ}$ > $90^{\circ}$ > $0^{\circ}$의 순으로 연륜경사각 $45^{\circ}$에서 휨 탄성계수는 12.0 GPa, 휨 강도는 55.8 MPa로 가장 높은 값을 나타내는 것이 확인되었다.

• 건축역사연구
• /
• 제15권2호
• /
• pp.23-38
• /
• 2006

During the repair and restoration of the Daewoongjeon Hall of Youngguksa Temple, species identification and tree-ring dating for both present wood elements and charred ones excavated under the Hall, were conducted. The species of 74 wood elements of Daewoongjeon Hall, were identified as Pinus densiflora Sieb. et Zucc. and only 1 was identified as exotic Pinus species. The latter wood, which was used in the laths, seems to have been replaced during past repairs. Many documentary records and various artifacts pertaining to Youngguksa Temple are being excavated, but none described precisely the construction date of the present Daewoongjeon Hall. Also, from beneath the Daewoongjeon Hall, cornerstone and foundation of previous building and several charred wood elements were excavated. In comparing the direction of the stone columns of foundation of the previous structure and the existing Daewoongjeon Hall, the previous structure was rotated in an angle of approximately $15^{\circ}$. Therefore, in order to find the association of the previous structure with the present Daewoongjeon Hall, tree-ring dating was conducted. The dating of 41 original timbers and 14 roof-filling timbers of the present construction elements revealed that the last annual ring was of A. D. 1703 with complete latewood, indicating that those woods was cut some time between the autumn of 1703 and spring of 1704, and the building was erected in 1704 when we assume no period of wood storage. The year of the last annual ring of the charred elements, which were excavated from beneath the Daewoongjeon Hall, was analyzed as 1674. The cutting year of the woods used for the present building began in 1698, therefore, it can be presumed that the Daewoongjeon Hall before the fire was a structure that was elected shortly after 1674 and that a catastrophic fire occurred some time between 1674 and 1698.

• Journal of the Korean Wood Science and Technology
• /
• 제36권3호
• /
• pp.55-60
• /
• 2008

본 연구는 목재의 재질에 대한 목탄 시용의 효과를 구명하기 위하여 수행되었다. 그 결과 묘목의 연륜폭은 대조구보다 목탄시용구에서 더 넓은 것으로 나타났다. 목탄시용에 있어서, 낙엽송탄이 가장 큰 연륜폭을 나타냈고 다음으로 잣나무탄, 파티클보오드탄, 상수리탄 순으로 나타났다. 만재율과 비중은 목탄시용구가 대조구보다 낮았으며 낙엽송탄에서 가장 낮았다. 가도관장은 대조구보다 분말탄 시용구에서 길게 나타났지만 입상탄에서는 유의한 차이가 없는 것으로 나타났다. 가도관폭은 목탄시용구와 무처리구 간에 유의한 차이가 없는 것으로 나타났다. 세포벽두께도 조재부의 경우 목탄시용구와 무처리구간에 유의한 차이가 없는 것으로 나타났으나, 만재부의 경우는 목탄시용구가 무처리구 보다 큰 것으로 나타냈다. 마이크로피부릴 경각은 입상탄 시용구에서 대조구보다 작은 것으로 나타났지만 분말탄 시용구와 입상탄 시용구 간에는 유의한 차이가 없는 것으로 나타났다. 모든 처리구에서 분말탄과 입상탄간에는 차이가 없는 것으로 나타났다.

• Journal of the Korean Wood Science and Technology
• /
• 제44권4호
• /
• pp.607-615
• /
• 2016

The delamination along the annual ring on the cross-section of laminae and the bonding strength according to the tangential angle between laminae were evaluated for the production of 3-ply cross-laminated timber (CLT) using domestic larch. Since there is no standard for CLT in Korea, the production and test of specimens for bonding strength followed the standard procedure of "Structural glued laminated timber" (KS F 3021). The standard specifies to exclude any measurement from the cracks of timbers resulted from drying or knots during delamination test of the glued laminated timbers. However, the failure of cross-sectional tissues along the annual rings was observed near the glue-line of all specimens during the delamination test. Because this phenomenon can generate defects in the CLT that may be exposed to various temperatures and relative humidities after the actual construction, the delamination percentage was measured by including this wood failure. As a result, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed inward was the lowest, which was around 13%, regardless of the annual ring direction of the middle lamina. On the other hand, the delamination percentage of the CLT which had been combined in such a way that the annual rings of outer lamina were directed outward was the highest, which was around 26%. Furthermore, end-split occurred in the outer lamina during the drying process of the boiling delamination test, which affected the delamination percentage. Therefore, the soaking delamination test was found to be more appropriate for evaluating the delamination strength of CLT. The block shear strength of larch CLT was $3.9{\pm}0.9$ MPa on average, which was 46% lower than the block shear strength requirement (7.1 MPa) of the standard, but satisfied the criteria of the block shear strength (3.5 MPa) of the European Standard (prEN 16351: 2013).

• Journal of the Korean Wood Science and Technology
• /
• 제11권1호
• /
• pp.5-11
• /
• 1983

This paper aims at gaining the informations atout the fibril angle at secondary walls of tracheids. The test specimens were taken from disks on stem wood of "Pinus koraiensis Sieb. et zucc". The method of measuring the fibirl angle was selected so-called "iodine method" that crystalline aggregates of iodine may be induced to form within the elongated interstices of the cellulose matrix of the secondary wall and that these elongated crystals are oriented parallel to the long axies of the fibrills of cellulose. The following conclusions may be drawn from the results of this investigation. 1) Gross average fibril angle was about $17.6^{\circ}$ on stem wood. 2) Its values seem to be greater for earlywood (avg.$19.8^{\circ}$) than for latewood tracheids (avg.$15.3^{\circ}$) in normal wood. 3) According to the increase of annual ring from pith to barks the orientation of fibril angle seems to be decrease gradually in normal wood. 4) In the case of height variation in trees the sample trees have a tendency to increase the orientation fibril angle to the increase of tree height in stem.

• 한국산림과학회지
• /
• 제109권1호
• /
• pp.62-71
• /
• 2020

이 연구는 땅밀림지에서 휘어져 자란 수목의 나이테를 분석함으로써 땅밀림이 지속적으로 진행되는가를 파악함으로써 땅밀림지 복구를 위한 기초자료를 제공하기 위하여 수행하였다. 땅밀림지의 각종 인자를 분석하고, 인장균열을 따라 휘어져 자라는 수목을 6개체 선정하여 휘어진 지점의 상부와 하부 단판을 채취하여 경사각을 측정하였다. 본 조사지의 지층 및 주 구성암석은 선캠브리아기에 형성된 회장암 지역으로 타 지층 및 관입암과 단층 및 습곡은 없으며, 땅밀림지 상단부에는 너널이 분포하고, 풍화암으로 이루어져 있다. 땅밀림지에서 휘어진 수목의 나이테 분석과 인공위성사진을 이용한 지형을 분석한 결과, 사면 최하단부에서부터 상단부까지 발생한 땅밀림 발생시기는 1999년부터 2011년까지로 분석되었다. 땅밀림으로 발생된 인장균열이 가리키는 방위각과 수목의 휘어진 각을 T-test한 결과 1% 수준에서 유의하였다. 따라서 땅밀림 지역의 인공위성사진을 통한 지형분석과 함께 휘어진 수목의 나이테분석, 지하수위 분석을 병행한다면 땅밀림 발생시기를 보다 면밀히 확인할 수 있을 것으로 사료된다.

• Journal of the Korean Wood Science and Technology
• /
• 제18권4호
• /
• pp.65-78
• /
• 1990

For the purpose of Improving the sounding boards for the conventional GAYAKUM, I was making approximately 202 specimens of radial board, 371 specimens of tangential board by cutting along the grain and the part of stem and 31 specimens of the disjointed traditional GAYAKUM made in Paulownia coreana. And it was conducted to measure specific gravity, dynamic Young's modulus, internal friction, resonant frequency, velosity of sound and width of annual ring by the method of the frexural vibration in a free-free bar in the audio frequency range. And it confirmed the juvenile wood by measuring wood fiber length of specimens. It was also conducted to investigate dynamic properties and moisture absorption by various heat-treatment and to test dynamic Young's modulus and internal friction for the disjointed conventional GAYAKUM. The results obtained were summarized as follow: 1. The Juvenile wood is located within about 7 annual rings from the pith in Paulownia coreana. 2. As increased with the specific gravity, the dynamic Young's modulus had more and more increased, but the internal friction had slightly decreased. 3. I think that radial board would be good for sounding board wood. because radial board is higher than tangential board in dynamic Young's mudulus and internal friction is lower than tangential board. 4. The value of mean dynamic Young's modulus on the conventional GAYAKUM, radial board and tangential board of 604 samples is $0.4283\pm0.037(\times10^{11}dyne/cm^2)$, $0.4316\pm(\times10^{11}dyne/cm^2)$ and $0.4234\pm0.112(\times10^{11}dyne/cm^2)$ respectively. The value of the radial board showed little higher than that of conventional GAYAKUM, but It had a similar tendency between conventional GAYAKUM and tangential board. 5. The annual ring width by four aspect is more narrow in north and west than that of others. 6. The values of specific gravity and dynamic Young's modulus in the mature wood showed higher than those of juvenile wood. 7. As the grain angle in the butt wood more increased to bark from pith, the dynamic Young's modulus were low. Then it was not good for sounding board. 8. It appeared that the heat-treatment for sounding board wood had a more effect to do the treatment of hotiron on surface after heat-treatment during 24 hours in $60^{\circ}C$ temperature. 9. As increased with the temperature, the rate of moisture absorption of heat-treatment wood had decreased. In conclusion, I thought that the sounding board wood for GAYAKUM would had the most effect to do the treatment of hotiron on surface after heat-treatment during 24 hours in $60^{\circ}C$ temperature using the radial board of mature wood.