• Journal of the Korean Wood Science and Technology
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• 제36권4호
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• pp.93-101
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• 2008

하중방향(섬유평행방향, 섬유직각방향)과 접합구(볼트, 드리프트 핀) 적층면방향(평행, 수직)에 따른 국내산 낙엽송집성재의 지압강도시험을 실시하였다. 지압시편은 5 ply의 집성재를 사용하였고, 접합구의 직경은 12, 16, 20 mm를 사용하였다. 시험결과는 다음과 같다. 1) 볼트와 드리프트 핀의 각 직경에 따른 평균최대지압강도는 섬유평행하중방향의 경우 비슷한 경향을 보였으며, 섬유평행하중방향의 평균최대지압강도가 섬유직교방향보다 1.50~2.31배 높게 나타났다. 평균지압강도의 경우 섬유평행하중방향시편은 직경 16 mm에서 20 mm로 증가할 때 20% 감소하였으며, 섬유직교방향은 뚜렷한 경향이 없었다. 2) 평균지압초기강성의 경우 섬유평행하중방향은 직경 16 mm일 때 가장 크게 나타났다. 드리프트 핀 접합부의 전단강도실험 시 초기강성과 평균지압초기강성은 직경이 증가할수록 비슷한 경향을 보였다. 3) 지압강도시험 시 섬유평행방향시편의 파괴형상은 직경이 작을수록 할렬파단을 보였다. 섬유직교방향의 시편은 대부분이 섬유평행방향으로 할렬파단이 일어났으며 볼트가 드리프트 핀 시편보다 더 많이 나타났다. 4) 지압강도예측식을 통해 구한 예측지압강도와 실제 5% 유사항복지압강도를 비교하였을 경우 섬유평행방향은 KBCS, NDS의 예측지압강도와 비슷하게 나타났으나, 섬유직교방향은 NDS에서 제안한 예측식이 잘 적용되는 것을 알 수 있었다.

• 자원환경지질
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• 제8권4호
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• pp.203-210
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• 1975

The engineering properties of some Gyeongsang sedimentary rocks with respect to the grain size and the orientation of bedding planes were studied. The suitability of the rocks for civil and architectural construction was also investigated. The porosity of the rocks increases in proportion to the grain size. The ratio of the strain due to stress perpendicular to the bedding planes to the strain resulting from stress parallel to the bedding planes increases as the grain size decreases. The study indicates however, that the ratio of Young's modulus due to stress perpendicular to the bedding planes to Young's modulus resulting from stress parallel to the bedding planes increases in proportion to the grain size. The compressive strength of the sandstones studied is much greater than the strength of the conglomerate or shale. Only the coarse grained sandstone can be used for civil and architectural construction, regardless of the orientation of bedding planes. The relationships between compressive strength and density, elasticity and porosity, and compressive strength and mineral content were also studied.

• Journal of the Korean Wood Science and Technology
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• 제40권4호
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• pp.287-293
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• 2012

본 연구에서는 현재 국내 목조건축에서 벽구성 재료로 많이 사용되고 있는 수입 OSB(배향성 스트랜드보드)를 국산 합판으로 대체하기 위해 OSB와 국산 합판의 못 접합부 전단성능을 비교 검토하였다. 주부재(잣나무)와 측면부재(OSB 합판)의 섬유 방향성(평행 직각)에 따른 전단성능은 합판에서 현저하였다. 결과, OSB와 합판 모두 현행 국내 기준인 못 접합부 기준 허용전단내력을 만족하는 것으로 나타났다. 그리고, 표면층에 MLH(열대산 활잡목)를 사용하고 7ply 구성한 합판(P-4 type)은 OSB보다 섬유방향에 관계없이 큰 전단성능을 나타냈다. 전반적으로 측면부재로서 합판을 사용할 경우 주부재에 대하여 섬유방향을 직교되도록 구성할 경우, 평행방향 구성보다 큰 전단성능을 발휘할 수 있음이 확인되었다.

• Journal of the Korean Wood Science and Technology
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• 제50권4호
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• pp.237-245
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• 2022

This study examined the structural performance of experimental parallel strand lumber (PSL) from a Larch veneer strand. The prototype of PSL from a Larch veneer strand was manufactured in the experimental laboratory and tested. The bending and dowel bearing strength were determined from the modulus of elasticity (MOE), modulus of rupture (MOR), and dowel bearing strength based on a 5% offset yield load. The test results indicated that the average MOR of PSL was higher than that of 2 × 4 dimension lumber, and the average MOE of PSL was lower than that of 2 × 4 dimension lumber. A linear relationship was observed between the MOR and MOE. The allowable bending stress of PSL was derived as specified in ASTM D2915 and compared with other research. The dowel bearing strength of PSL in parallel to the grain was approximately double that perpendicular to the grain of PSL. A comparison of several theoretical calculations based on each national code for the dowel bearing strength was conducted, and some theoretical equations produced results closer to the experimental results when it was parallel to the grain, but the difference was higher in the case perpendicular to the grain. The test results showed that PSL made with Japanese larch veneer strands appeared to be suitable for a raw material of structural composite lumber (SCL) appeared to be used as a raw material for SCL.

• Journal of the Korean Wood Science and Technology
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• 제47권1호
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• pp.40-50
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• 2019

The aim of this study was to investigate the effects of density, temperature, size, and grain direction on measurement of moisture contents (MC) of wood materials non-destructively. The MC of different sizes of solid wood, glulam, and CLT from larch (larix kaempferi, $560kg/m^3$) and pine (pinus koraiensis, $430kg/m^3$) were measured using the dielectric type and resistance type meters. The specimens were conditioned in the environmental chamber to be equilibrium moisture content (EMC) of 12 % and 19 %. When density setting in dielectric type meter was increased from $400kg/m^3$ to $600kg/m^3$, the MCs of specimen (S-L-100-E) were decreased from 13.4 % to 11.3 %. However, when wood group (WG) setting in resistance type meter was changed from WG1 to WG4, the measured MCs were increased from 9.2 % to 12.3 %. When temperature setting in resistance type meters was changed from 0 to $35^{\circ}C$, the MC was decreased from 17.0 % to 13.0 %. The MCs measured by dielectric type meter for larger specimens (S-L-100-E_11.3 %, G-L-240-E_11.7 % and C-L-120-E_12.8 %) were higher than those of small size specimens (S-L-30-E_8.7 %, G-L-150-E_10.3 %, and C-L-90-E_9.7 %). The MCs measured by resistance type meter for larger specimens (G-L-240-E_11.6 % and C-L-120-E_13.3 %) were also higher than those of small size specimens (G-L-150-E_10.4 %, and C-L-90-E_11.8 %). The resistance type meter was not affected by the grain direction but the dielectric type meter were affected by the grain direction. The MC measured by resistance type meter for G-L-120-E perpendicular to grain direction was 11.5 % and the measured MC parallel to grain direction was 11.3 %. The MC measured by dielectric type meter parallel to grain direction (12.1 %) was higher than that measured perpendicular to grain direction (10.7 %).

• Journal of the Korean Wood Science and Technology
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• 제26권1호
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• pp.87-96
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• 1998

The bending performances were evaluated at the radiata pine plywood through veneer compositions encompassing veneer quality, ply-numbers and overlays of the high density- or medium density-phenol resin impregnated sheets (hereafter abbreviated as resin sheets) on the raw plywood. In addition, a prediction on the bending MOE of veneers and plywoods was carried out by the nondestructive testing with stresswave timer. The summarized results were as follows: I. Bending strength and bending MOE of resin sheets-overlaid plywoods in parallel surface grain direction through 5 and 7ply were increased by 13 to 45% and 17 to 34%, respectively. Resin sheets-overlay occurred an increasing effect of the strength efficiency i.e. strength perpendicular-to-grain direction versus that parallel-to-grain direction, showing the phenomenon that the plywood strength becomes greater at the perpendicular-to-grain direction of 7ply than at that of 5ply. Displacement at bending failure had a greater trend at 7ply than at 5ply, and was decreased by resin sheets-overlay. 2. After the nondestructive bending MOEs were measured for individual veneers, these veneers were rearranged in plywood-manufacture. In these plywoods, including resin sheets-overlay, the actual MOE was predictable with feasibility of $R^2$=0.53, and also the nondestructively-evaluated MOE was lower by 20% in raw plywood, and higher 20% in LVL than actual bending MOEs.

• 한국재료학회지
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• 제11권12호
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• pp.1042-1046
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• 2001

Co-22%Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure(SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. We prepared 1000 $\AA$-thick Co-22%Cr films on 2000 $\AA$- SiO$_2$/Si(100) substrates at the deposition rate of 100 $\AA$/min with substrate temperatures of 3$0^{\circ}C$, 10$0^{\circ}C$, 15$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$, respectively. We employed a vibrating sample magnetometer(VSM) to measure the B-H loops showing the saturation magnetifation, coercivity, remanence in in- plane and out- of- plane modes. In- plane coercivity, perpendicular coercivity, and perpendicular remanence increased as substrate temperature increased, how-ever they decreased after 30$0^{\circ}C$ slowly. Transmission electron microscope (TEM) characterization revealed that the self organized nano structure (SONS) appears at the elevated substrate temperature, which forms fine Co-enriched phases inside a grain, then it eventually affect the perpendicular magnetic property. Our results imply that we may tune the perpendicular magnetic properties with SONS obtained at appropriate substrate temperature.

• Journal of the Korean Wood Science and Technology
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• 제35권3호
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• pp.10-21
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• 2007

집성재 다우얼 접합부가 적용되는 기둥의 기초, 기둥-보 접합부에는 회전이 발생하므로 접합부의 모멘트 성능에 대한 연구가 필요하다. 접합부의 회전에 의해서 섬유방향과 각을 이루어 작용하는 하중을 섬유방향에 평행한 하중과 수직한 하중으로 단순화 하여 거동을 해석하고 예측하였다. 드리프트 핀의 휨강도 및 지압응력을 평가하였으며, 섬유방향에 평행한 인장하중과 수직한 인장하중을 받는 접합부의 끝면 거리를 다르게 하여 접합부의 인장형 전단성능을 시험하였고 회전이 작용하는 접합부는 드리프트 핀의 개수와 배열 방향을 다르게 하여 시험하였다. 접합부에 인장하중이 작용할 때 항복 이후의 변형량은 드리프트 핀의 소성변형에 의해서 발생하며, 집성재의 끝면 거리 확보에 의한 드리프트 핀의 변형 흡수가 접합부 전체의 변형량에 영향을 주는 것으로 판단된다. 2개의 드리프트 핀이 섬유방향에 평행하게 배열된 경우(b2h)에는 섬유방향에 수직한 인장하중 거동을 나타내고, 2개의 드리프트 핀이 섬유방향에 수직하게 배열된 경우(b2v)에는 섬유방향에 평행한 인장하중 거동을 나타내는 것으로 평가된다. 4개의 드리프트 핀이 정사각 배열된 접합부의 경우(b4)에 2개의 드리프트 핀이 섬유방향에 평행하게 배열된 접합부(b2h)의 약 1.7배의 하중 성능을 나타냈으며, 접합부에 회전이 작용하여 섬유방향과 각을 이루는 하중을 섬유방향에 대한 평행 또는 수직한 하중으로 치환하여 거동을 평가, 예측하는 것이 가능하다고 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제29권4호
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• pp.1-8
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• 2001

본 실험은 강판삽입형에 드리프트 핀, 볼트를 이용한 2가지 형태의 접합부의 강도 특성을 검토하였다. 하중 방향은 섬유평행방향 하중 (0도 하중)과 섬유직교방향 하중 (90도 하중)을 가하여 하중방향의 차이 및 접합구에 따른 강도 특성을 비교하였다. 소나무재의 강판 삽입의 드리프트 핀, 볼트 인장형 전단강도 실험에서 다음과 같은 결과를 얻었다. 1. 같은 단거리의 섬유평행방향 하중시 최대하중은 접합구의 직경이 증가함에 따라 증가되는 경향을 보였으며, 90도 하중인 경우 드라프트핀, 볼트 접합부는 2가지 접합구 직경(10 mm, 12 mm)에서 모든 소나무 시편이 할렬파괴 되었다. 2. 하중-변형 곡선의 초기 직선영역을 나타내는 직선과 접합구 직경의 5% 만큼을 횡축의 정방향으로 평행 이동시킨 접합부의 항복하중(Py)과 최대 하중비의 증가 정도는 0도 하중의 경우가 높고, 볼트의 접합에서 높았다. 또한 세장비가 증가될수록 높은 경향을 나타냈다. 3 항복 추정식으로 구한 항복하중과 실험값에서 5% 차감한 항복하중은 볼트 접합부에 비해 드리프트 핀 접합부가 추정치와 실험치가 잘 일치되었다.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.100-104
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• 2013

Bearing occurs by the rotations of members induced from horizontal or vertical load at traditional wooden joint in frame. The bearing between wooden members is not occurring at the whole surface of joint, but occurring only at the particular bearing area. In this study, partial bearing according to the different grain direction was evaluated. The partial compressive strength showed 3 times higher than pure compressive strength perpendicular to grain, 1.5 times higher than parallel to grain and 3.3 times higher than both of them. It is expected that this result can be very importantly applied when evaluating and analyzing the actual behavior of traditional wooden mortise and tenon joint.