• 한국지진공학회논문집
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• 제21권4호
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• pp.163-170
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• 2017

The need for eco-friendly building materials such as engineered wood has increased to reduce carbon emissions. Although the range and height of engineered wood buildings are gradually increasing in North America and Europe, engineered wood is mainly used for low-rise residential buildings in Korea. In order to reduce carbon emissions more, therefore, it needs to expand the use of engineered wood by applying it to various buildings with different uses or more stories. With this background, the aim of this study is to investigate the applicability of engineered wood for 9-story office buildings. Since a 9-story building with engineered wood only is not allowed in KBC, an example building has RC ordinary shear walls as the lateral force resisting system while engineered wood is only used for gravity load resisting moment frames. Another example building is also used for comparison where both lateral and gravity load resisting systems are designed by RC. The applicability of engineered wood is investigated by comparing the seismic performance and the amount of carbon emission of both buildings. The result shows that the seismic performance of both buildings was not significantly different while the amount of carbon emission of the engineered wood building was much less then the RC building. Based on this result, engineered wood is sufficiently applicable to 9-story office buildings even though it still needs to pay attention to the shear design of reinforce concrete walls.

• Journal of the Korean Wood Science and Technology
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• 제25권3호
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• pp.43-49
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• 1997

The lengths of fibers and vessel elements, vessel diameters, and ray spacings of tension and opposite woods in Quercus mongolica Fischer and their radial variations were examined. Crystallinity indices and crystallites orientations of tension, opposite and lateral woods were also investigated. The lengths of fibers and vessel elements, and ray spacings of tension wood were longer and denser than those of opposite wood, respectively. In the latewood, the vessels of tension wood had a little larger diameters than those of opposite wood. whereas the vessel diameters of earlywood were similar in both woods. With the exception of vessel diameters of earlywood, there were differences between tension and opposite woods in all anatomical characteristics examined. In the radial variation pattern, the fiber lengths of both woods increased markedly to about 15th annual ring and thereafter remained virtually constant. The vessel element lengths of earlywood in tension wood increased to certain annual ring and thereafter were stabilized, but opposite wood had a relatively constant trend from pith to bark. Those of late wood in both woods increased to certain annual ring and thereafter showed constant patterns. Vessel diameters appeared to show similar trend in both woods. Ray spacings decreased to about 15 annual ring and thereafter were stabilized in both woods. In the fine structures, tension wood had higher crystallinity index and better crystallites orientation than opposite and lateral woods.

• Journal of the Korean Wood Science and Technology
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• 제17권2호
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• pp.1-12
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• 1989

To study the structure of opposite wood in the angiosperms. samples were cut from stems and branchs of 10 spcies growing in Korea. The opposite side was defined as being along a line passing from the most wide annual ring of the tension wood on the upper side to the pith and extrapolated through the opposite side. lateral sides being on the right and left of this line. The stem woods growing almost horizontally were surveyed the structural features of the well-developed opposite wood for the tension wood. In the annual-ring of the well-developed opposite woods. an investigation was made on how the dimension of elements, microfibril angles. and cell wall layers change from tension side to opposite side. The structural characteristics of opposite wood in hardwoods realized in this study are as follows: 1. The vessel diameters increased continuously to ward the opposite side in which the values were maximum. The vessel length also increased toward opposite side. but the rates of increase were smaller than those in the vessel diameters. 2. The wood fiber length were decreased from tension toward opposite side. but the rates of decrement were f1actuated within the sampled species. 3. The microfibril angles had the minimum values on the tension side. then increased steeply toward the opposite side in which the values maximum. 4. In the percentage of elements the vessel elements increased continously at a relative rate from the tension to opposite side, whereas the values of the wood fibers were lower in the opposite than the tension side, but the' variation patterns of rays were not seem distinctly. 5. The component layers of the wood fiber in the opposite woods were very similar to the lateral woods.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.728-736
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• 2017

In this study, the bending behavior of cross-laminated timber (CLT) connected by nails were investigated. Especially, the load-carrying capacity of the nail-jointed CLT under out-of-plane bending was predicted by the lateral resistance of the used nails. Three-layer nail-jointed CLT specimens and a nail connection were manufactured by 30 mm (thickness) ${\times}$ 100 mm (width) domestic species (Pinus koraiensis) laminas and Ø$3.15{\times}82mm$ nails using a nail-gun. Shear test for evaluating the nail lateral resistance and bending test for evaluating the load-carrying capacity of the nail-jointed CLT under out-of-plane bending were carried out. As a result, two lateral resistance of the used nail, the 5% fastener offset value and the maximum value, were 913 N and 1,534 N, respectively. The predicted load-carrying capacity of the nail-jointed CLT by the 5% offset nail lateral resistance was similar to the yield points on the actual load-displacement curve of the nail-jointed CLT specimens. Meanwhile, the nail-jointed CLT specimens were not failed until the tension failure of the bottom laminas occurred beyond the maximum lateral resistance of the nails. Thus, the measured maximum load carrying capacities of the nail-jointed CLT specimens, approximately 12,865 N, were higher than the predicted values, 7,986 N, by the maximum nail lateral resistance. This indicates that the predicted load-carrying capacity can be used for designing a structural unit such as floor, wall and roof able to support vertical loads in a viewpoint of predicting the actual capacities more safely.

• 한국가구학회지
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• 제18권2호
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• pp.111-119
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• 2007

An experiment was conducted to know the safranine impregnation distance from surface to inward using 6 different hardwood species. During impregnation, 3 parameters were applied-vacuum, pressure and soaking time. Only vacuum treatment did not increase the permeability of wood. Vacuum followed by pressure increased the penetration depth of safranine in radial, tangential and longitudinal direction. Longitudinal penetration was found easy to impregnate. Comparing with radial and tangential direction, radial penetration was found easy. There was a striking difference among sapwood and heartwood permeability. Safranine input depth was found highest in diffused porous wood rather than in ring porous wood. At increased vacuum and pressure, safranine penetration was found easy.

• Journal of the Korean Wood Science and Technology
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• 제39권5호
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• pp.406-419
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• 2011

This study was carried out to offer basic information on the wood anatomy of domestic yellow-poplar (Liriodendron tulipifera L.), a new plantation species selected by Korea Forest Service as one of the promising hardwood and bioenergy sources of the future, through comparison of stem wood with root wood in the qualitative and quantitative features. In the qualitative anatomical features, growth rings were distinct in stem wood but relatively less distinct in root wood. And stem wood appeared to have pores in radial multiples of 2 to 5, sometimes clusters but root wood to have pores in radial multiples of 2 to 3, rarely clusters. And numbers of bars in scalariform perforation plates were somewhat numerous in vessel elements of root wood than in those of stem wood. Interestingly, on the other hand, more extraneous materials in the wood rays of tap root than in those of lateral root and stem were confirmed in the chemical composition analyses. In the quantitative anatomical features, pore densities were significantly greater but vessel elements were considerably narrower in stem wood than in root wood. Vessel elements and wood fibers of root wood were considerably longer than those of stem wood. Rays were somewhat more numerous in stem wood than in root wood, and only ray heights of stem wood were more or less greater in cell numbers but both ray heights and widths of stem wood were lower in dimension than those of root wood. The anatomical differences between stem wood and root wood were thought to be associated with different growth environments between the stem above ground and the root below ground.

• 한국가구학회지
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• 제17권3호
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• pp.29-36
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• 2006

Juvenile and matured wood of Populus tomentiglandulosa species of Salicaceae native grown in Korea was observed by FE-SEM and optical microscope. Species is characterized by mostly diffuse-porous, simple perforation plates, polygonal alternate non-vestured intervessel pit, medium length of vessel elements and fibres, non-septate very thin walled libriform fibres and exclusively uniseriate procumbent rays. Axial parenchyma was absent or extremely rare. Vessel and fibre length were longer in both matured and juvenile latewood than those of earlywood. Ray cell lumen diameter, ray length, number and diameter of endwall pit in ray cell, endwall pit, number and diameter of pit in lateral wall of one ray parenchyma cell, vessel ray pit number and diameter vary from juvenile early and latewood to matured wood.

• Journal of the Korean Wood Science and Technology
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• 제30권4호
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• pp.96-105
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• 2002

전단벽은 현대식 경골목조건축에서 바람이나 지진 등에 의한 측방하중에 대한 저항력을 제공하는 가장 중요한 요소 중의 하나이다. 전단벽에서 건물에 전달된 측방하중은 벽의 스터드와 덮개재료 사이의 못접합부를 통하여 덮개재료로 전달되고 덮개재료에 전달된 하중은 판재의 면전단력에 의하여 지지된다. 따라서 실제 전단벽에서 측방하중에 대한 저항력을 결정하는 가장 중요한 요소는 못접합부라고 할 수 있을 것이다. 이 연구에서는 스터드와 판재 사이의 못접합부에 대한 강성 및 강도를 측정하였으며 이 값들은 전단벽의 찌그러짐 저항력을 예측하는 이론모형의 입력자료로 사용되었다. 이론모형의 예측치의 정확성을 검증하기 위하여 판재 한 장으로 구성된 전단벽의 전단시험을 수행하였다. 못접합부의 강성은 스터드 부재의 섬유방향에 의하여 영향을 받았으나 판재의 방향은 거의 영향을 미치지 않는 것으로 나타났다. 전단하중 하에서 못접합부나 전단벽의 거동은 3개의 직선구간으로 나나낼 수 있었으며 이론모형 I보다 이론모형 II의 예측치가 더 정확하였다.

• Journal of the Korean Wood Science and Technology
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• 제51권1호
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• pp.58-66
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• 2023

In light-frame timber construction, the shear wall is one of the most important components that provide resistance to lateral loads such as earthquakes or winds. According to KDS (Korea Design Standard) 42 50 10, shear walls are to be constructed using wood-based structural sheathing, with studs connected by 8d nails spaced 150 mm along the edge and 300 mm in the field. Even though small-scale residential timber building can be designed to exhibit seismic resistance using light-frame timber shear walls in accordance with KDS 42 50 10, only the abovementioned standard type of timber shear wall is available. Therefore, more types of timber shear walls composed of various materials should be tested to measure their seismic resistance, and the results should be incorporated into the future revision of KDS 42 50 10. In this study, the seismic resistance of shear walls composed of structural timber studs and wood-based structural sheathing with reinforced nailing is tested to evaluate the effects of the reinforcement. For the nailing reinforcement, shear wall specimens are constructed by applying nail spacings of 75-150 mm and 50-100 mm. For the shear wall specimens with one sheathing and reinforced nailing, the shear strengths are 1.7-2.0 times higher than that of the standard shear wall (nail spacing of 150-300 mm). The shear strength of the shear walls with sheathing on both sides is 2.0-2.7 times higher than that of the standard shear wall.

• Earthquakes and Structures
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• 제20권1호
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• pp.97-107
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• 2021

A comprehensive study on seismic performance of wood frame building in hilly regions is presented. Specifically, seismic fragility assessment of a typical wood frame building at various locations of the northeast region of India are demonstrated. A three-dimensional simplified model of the wood frame building is developed with due consideration to nonlinear behaviour of shear walls under lateral loads. In doing so, a trilinear model having improved capability to capture the force-deformation behaviour of shear walls including the strength degradation at higher deformations is proposed. The improved capability of the proposed model to capture the force-deformation behaviour of shear wall is validated by comparing with the existing experimental results. The structural demand values are obtained from nonlinear time history analysis (NLTHA) of the three-dimensional wood frame model considering the effect of uncertainty due to record to record variation of ground motions and structural parameters as well. The ground motion bins necessary for NLTHA are prepared based on the identified hazard level from probabilistic seismic hazard analysis of the considered locations. The maximum likelihood estimates of the lognormal fragility parameters are obtained from the observed failure cases and the seismic fragilities corresponding to different locations are estimated accordingly. The results of the numerical study show that the wood frame constructions commonly found in the region are likely to suffer minor cracking or damage in the shear walls under the earthquake occurrence corresponding to the estimated seismic hazard level; however, poses negligible risk against complete collapse of such structures.