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1.
Knots have been considered an undesirable visual feature of lumber. To clarify the essence of this visual undesirability,
eye-tracking data from 20 subjects, who freely observed 55 images of wood wall panels, were recorded and distribution maps
of eye-fixation pauses were composed. These maps were compared with the arrangement of knots on each knotty wall panel image
and the visual inducement of knots was evaluated using a new numerical index of pausing probability. The present study is
the first to objectively quantify the visual inducement of knots. In addition, the subjective noticeability of knots and ten
visual impressions of each wood panel image were investigated by a sensory evaluation. There was a very clear linear relationship
between the visual inducement of knots and the subjective noticeability of knots. A correlation analysis suggested that many
visual impressions of wood wall panels were influenced by a complementary effect between the subjective noticeability of knots
and the visual inducement of knots. The visual impact of knots was masked to some extent by special visual stimuli such as
deep red grooves on the wood wall panels.
This study was presented at the 56th and 57th Annual Meetings of the Japan Wood Research Society, Akita and Hiroshima, August
2006 and August 2007, respectively 相似文献
2.
To clarify if eye fatigue is lessened when looking at wood, we carried out objective examinations using a near-point ruler and also performed sensory evaluations. Visual contact target materials were a white plastic panel, a black plastic panel or a wood panel which had Japanese ash flat grain surface. Each size of the materials was 140 × 280 mm. Test subjects were 30 undergraduate and graduate students. Each subject’s visual distance to a panel was 40–50 cm. The results showed that subjects suffered from more eye fatigue when looking at white and black plastic panels compared to looking at the wood panel in objective examinations. In sensory evaluations, almost all subjective symptom items for eyes and head progressed when subjects looked at white plastic panel or black plastic panel. However, almost no progression of subjective symptoms was noted when subjects looked at the wood panel. In both objective examinations and sensory evaluations, eye fatigue was most highly associated with the black plastic panel, followed by the white plastic panel and, finally, the wood panel. 相似文献
3.
This study aimed to clarify the physiological effects of touching hinoki cypress (hereinafter called “hinoki”) (Chamaecyparis obtusa) wood with the palm of the right hand on brain activity and autonomic nervous activity. Twenty-two female university students (mean age 21.1?±?0.2 years) participated in the study. As an indicator of brain activity, oxyhemoglobin (oxy-Hb) concentrations were measured in the left/right prefrontal cortex using near-infrared time-resolved spectroscopy. Heart rate variability (HRV) was used as an indicator of autonomic nervous activity. The high-frequency (HF) component of HRV, which reflected parasympathetic nervous activity, and the low-frequency (LF)/HF ratio, which reflected sympathetic nervous activity, were measured. Plate (300?×?300 mm) of uncoated hinoki was used as tactile stimulation. Marble was used as a control material. After sitting at rest with their eyes closed, the participants touched the materials for 90 s with their eyes still closed. The results showed that tactile stimulation with hinoki significantly decreased oxy-Hb concentration in the left prefrontal cortex and increased ln(HF) reflected parasympathetic nervous activity compared with marble. In conclusion, our study showed that touching hinoki wood with the palm calms prefrontal cortex activity and increases parasympathetic nervous activity, thereby inducing physiological relaxation. 相似文献
4.
Jung-Kwon Oh Jung-Pyo Hong Chul-Ki Kim Sung-Jun Pang Sang-Joon Lee Jun-Jae Lee 《Journal of Wood Science》2017,63(1):45-55
A cross-laminated timber (CLT) wall plays the role of resisting shear stress induced by lateral forces as well as vertical load. Due to the press size, CLT panels have a limitation in size. To minimize the initial investment, some glulam manufactures wanted to make a shear wall element with small-size CLT panels and panel-to-panel connections and wanted to know whether the shear wall would have equivalent shear performance with the wall made of a single CLT panel. In this study, this was investigated by experiments and kinematic model analysis. Two shear walls made of small CLT panels were tested. The model showed a good agreement with test results in the envelope curve. Even though the shear walls were made of small panels, the global peak load did not decrease significantly compared with the wall made of a single CLT panel, but the global displacement showed a large increase. From this analysis, it was concluded that the shear wall can be designed with small CLT panels, but displacement should be designed carefully. 相似文献
5.
The positive and negative effects of the residual stand edge at a strip-clearcut site were examined on the initial growth of hinoki (Chamaecyparis obtusa) planted in areas with diverse topography. On the south edge, the gap light index was lower than on the north edge and strip center; however, the vapor pressure deficit was also lower than on the north edge and strip center, which resulted in lower physiological stress of hinoki on the south edge. Tree size on the south edge did not exceed that on the north edge and strip center. These results indicated that low light conditions due to residual trees negatively affected growth on the south edge even under the positive effect of microclimate alleviation. In valley, tree size in the second year after planting was smaller than on ridge and slope; however, tree growth during the following 2 years was higher in valley. Surface soil in valley was thinner with rockier substrates than on ridge and slope; that is, soil sedimentation type and substrates influenced the initial growth of hinoki with undeveloped roots, and after that, topography started to influence growth, probably because hinoki roots penetrated into deeper soil, which is influenced by the water gathering capacity of the valley. The initial growth of hinoki at the strip-clearcut site was predominantly affected by light rather than microclimate alleviation. This alleviation is expected to disappear when hinoki trees planted in the strip center grow enough to give additional shade to slow-growing edge hinoki. 相似文献
6.
To clarify the visual effects of room interior with wooden materials on humans, pulse rate, blood pressure, and brain activity
were measured while the subjects were exposed to visual stimuli using actual-size model rooms. The wood ratios (the ratio
of the area covered with wooden material to the whole area of the ceiling, walls, and floor) of the rooms were 0%, 45%, and
90%. Subjective evaluation was also conducted. In the 0% room, diastolic blood pressure decreased significantly, but the observed
change in the autonomic nervous activity was relatively small. In the 45% room, a significant decrease in the diastolic blood
pressure and a significant increase in pulse rate were observed. This room tended to have the highest scores in subjective
“comfortable” feeling. The 90% room caused significant and large decreases in systolic blood pressure and diastolic blood
pressure at the beginning of the test, but the large coverage of wood appeared to cause a rapid decrease in brain activity
and an increase in pulse rate. The present study demonstrated that a difference in wood ratio in the interior caused different
physiological responses, especially in the autonomic nervous activity, by using actual-size rooms for the first time. 相似文献
7.
Yoshio Kijidani Yoshimitsu Fujii Keita Kimura Yoshitake Fujisawa Yuichiro Hiraoka Ryushi Kitahara 《Journal of Wood Science》2012,58(3):195-202
It was previously believed in Japan that the wood qualities of hinoki (Chamaecyparis obtusa) were superior to sugi (Cryptomeria japonica). However, few studies of wood properties such as MFA (microfibril angle of S2 layer in secondary wall of tracheid) have been completed for hinoki. Some reports have found that hinoki plus tree families have similar mechanical properties to sugi. Here we report the characteristics of MFA and density of hinoki half-sib families in a progeny test stand. There were significant differences in MFA and density between families. The wood properties of two families, Nakatsu 3 and Kanzaki 5, are stable in radial pattern and suitable for structural use. Early selection of hinoki families by MFA and density may be difficult. Effects of MFA and density on E d (dynamic modulus of elasticity) of logs differed between families. The effects of growth rate on MFA and density differed between families and also between juvenile and mature wood. The faster growth rate in Nakatsu 3 appeared to improve wood properties and increase E d of logs, although in many other families, faster growth rate had negative effects on desirable wood properties for structural use. 相似文献
8.
This study examined the effects of contact with wood on the living human body using a physiological index and subjective evaluation.
Consecutive blood pressure measurements were used as the physiological index, and sensory evaluation using the semantic differential
(SD) method was used for subjective evaluation. Consideration was also given to cases in which materials were cooled and heated
as well as kept at room temperature, to eliminate the effects of heat flux due to differences in thermal conductivity between
wood and other materials. It was found that contact with wood produced coarse/natural sensations, with no associated increase
in systolic blood pressure. Contact with cold wood created subjectively dangerous/uncomfortable but still coarse/natural sensations,
also with no associated increase in blood pressure; therefore, there was no correspondence between subjective evaluation and
physiological responses. Contact with aluminum kept at room temperature and cold acrylic plastic created flat/artificial and
dangerous/uncomfortable sensations, with an associated significant increase in blood pressure; thus, there was a close correlation
between subjective evaluation and physiological responses. It was therefore concluded that contact with wood, unlike artificial
materials such as aluminum, induces no physiological stress even when kept at room temperature or cooled.
Part of this report was presented at the 48th Annual Meeting of the Japan Wood Research Society in Shizuoka, April 1998 相似文献
9.
Masanobu Tabata Takashi Kato Masatoshi Ohkubo Yasuhisa Abe Shuichiro Yoshinaga 《Journal of Forest Research》2002,7(2):105-112
The rot ofChamaecyparis obtusa (hinoki) trees was studied in the northern part of Kagawa Prefecture, Japan. Among 158 hinoki examined, butt rot was found
in 28.6, 58.3, and 100% of trees in the 29, 30, and 34-year-old stands, respectively. All trees with butt rot, and 11 trees
without it had rotted roots. Thirteen hinoki were peeled byCervus nippon (sika deer) and all of them were infected with butt rot. The maximum height of rot in deer-damaged trees was 2.6 m from the
ground level, but was 1.9 m in undamaged trees. About eighty-two percent of rotted trees showed rotted areas of less than
40 cm2 on the cross section of stems at the ground level. White mycelia and black flecks sometimes appeared in the rotted wood.
Basidiocarps of polyporaceous fungus were often found on felled logs and rotted stumps of hinoki and identified asPerenniporia subacida. Basidiomycetous fungus was isolated frequently from rotted wood of roots and stems, and determined to beP. subacida by comparative study on cultural characteristics. An inoculation experiment and wood-decay test proved that the fungus was
the cause of the rot of hinoki. Few absorbing roots of living trees were found in the clayey subsurface soil of the high dry
bulk density and the less soil aeration. Some absorbing roots had root rot and the rot spread from the base of the absorbing
root to the central part of the woody root. This is the first report on the rot of hinoki caused byP. subacida in Japan. 相似文献
10.
A model to predict bending stiffness of oriented strandboard (OSB) was tested with pilot plant experimental data. The experimental
procedure developed in this study is unique in that it allows the model to be tested for extensive vertical configurations
of strand angle distribution. After validation, the model was used to simulate a typical three-layer cross-oriented OSB panel
with a vertical density profile and strand angle distribution measured on industrial panels. Analysis of the simulated vertical
distribution of modulus of elasticity (MOE) indicated that the layers near the panel surfaces contributed much more to the
effective parallel panel MOE than those close to the panel thickness center, with 80% of parallel MOE coming from the top
41% of weight and 32% of thickness. The effectiveness of methods to increase parallel bending stiffness through improving
mat structure was evaluated. Increasing face/core weight ratio from 54/46 to 66/34 resulted in a 3.7% increase in simulated
parallel MOE. Alignment of strands in face layers was identified having a greater potential to increase parallel MOE. Simulations
with three improved strand angle distributions showed gains of 5.7, 12.0 and 19.8% in parallel MOE compared with a typical
strand angle distribution of industrial OSB panels. 相似文献
11.
Considering increasing rate of Iran population and consumption of wood panels, the authors investigated the per capita consumption of wood panels during the years from 1997 to 2007. The exponential smoothing method was used to obtain a per capita consumption pattern of wood panels in Iran for estimating demand of wood panels by the year of 2012. Results show that the consumption of particleboard, fiberboard, and medium density fiberboard in Iran will increase by 33%, 72% and 107 %, respectively, by the year of 2012; however, the consumption of plywood will increase only by 7% by 2012. The deficient amount of wood panels in Iran is estimated over 1400000 m3. The results of this study provide the technique reference for planners of wood panel industries in Iran in capital investment decisions. 相似文献
12.
Physical and mechanical properties of medium density fiberboards (MDF) made from various mixtures of wood fibers and stone pine (Pinus pinea L.) cones were evaluated using European standards. MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from mixtures of wood fiber/cone flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 percents, respectively. Addition of the cone flour into the MDF significantly reduced formaldehyde emission from the panel. In addition, the addition of 10% cone flour also improved water resistance of the MDF panels made using urea–formaldehyde (UF) resin. However, further addition of the cone flour into the panel negatively influenced their water resistance. Flexural properties and internal bond strength decreased with the increase of cone flour content in the panel. The UF resin is the main source of formaldehyde emission from the UF-bonded wood-based panels. Depending on addition of the cone flour in the panels, the formaldehyde emission values ranged from 2.6% to 55.3% lower than the panels made from 100% wood fiber. Based on the findings obtained from this study, pine cone can be used as a renewable biological formaldehyde catcher as an alternative to the traditional formaldehyde catchers for E1 Class MDF manufacture. 相似文献
13.
This study was conducted to investigate the susceptibility of various wood composite panels exposed to wood-deteriorating fungi. Five wood-attacking fungi (three mold fungi, one brown rot fungus, one white rot fungus) were inoculated into four types of commercial wood composite panels (plywood, oriented strand board, particleboard, and medium-density fiberboard). One solid wood sample was included as a control. The attacking patterns of the fungi in each panel was observed by scanning electron microscopy. The weight losses due to the exposure were compared. All wood composites were more or less susceptible to all fungi inoculated. The attacking mode of the fungi was highly dependent on the types of wood composite, which had inherently different shapes of voids owing to different shapes and characteristics of the raw furnish materials used. Plywood and medium-density fiberboard showed a large weight loss after an 8-week exposure to decay fungi. Plywood is the most susceptible to white and brown rot fungi. This study indicates that all wood composite panels should undergo careful consideration to prevent fungal deterioration when they are used for exterior and humid interior applications. 相似文献
14.
Satoshi Sakuragawa 《Journal of Wood Science》2006,52(4):290-294
Efforts were made to quantify the impact of visual stimulation from interior wood finishes on the impression of room interiors,
using feelings about living activities as indicators. Four types of room interiors with interior wood finishes used in different
proportions were simulated. The room interiors were photographed from the same viewpoint. A survey was conducted by interviewing
200 test subjects. As a result of the analysis of principal components, it was found that desires of living activities obtained
from the four photographs consisted of two factors: desires for calmness and desires for activities. A great desire for calmness
was obtained from photographs showing wood materials. A weak desire for calmness and a strong desire for activities were obtained
from a photograph that showed no wood materials. Great desires for both calmness and activities were obtained from a photograph
showing wood materials used only as flooring material. As for an evaluation of “living,” the photograph of a room interior
without wooden materials was evaluated as a place that test subjects did not feel like living in. The photograph showing wood
materials used only as flooring material was evaluated as the place that test subjects most felt like living in, and considered
most suitable as a living space. 相似文献
15.
《Wood material science & engineering》2013,8(2):95-110
Abstract Wood moisture content of coated panels of Scots pine sapwood was recorded during 24 months natural weathering in Vienna by logging electric resistance and temperature near the surface. Eight coating systems with various film thicknesses were used, including three solvent borne alkyd stains, three water borne acrylic stains and two water borne acrylic paints. At five sites in Europe wood moisture content of panels coated with three solvent borne alkyd stains, a brown acrylic stain and a white opaque acrylic paint was recorded weekly by changes in panel mass. Fluctuations in wood moisture content were influenced by the film thickness, water permeability and colour of the coating systems used. Degradation phenomena led to decreasing moisture protection of less durable coating systems over time of exposure. The exposure site clearly affected wood moisture content in the panels. 相似文献
16.
17.
Pollen dispersal was estimated in two test plots in a hinoki (Chamaecyparis obtusa) seed orchard using a chloroplast DNA marker, the spacer region between thetrnD andtrnY genes, and SSCP (single strand conformation polymorphism). In Plot 1, 2,020 seeds from 40 trees within 30 m of the marker
tree were analyzed using the PCR-SSCP method. In Plot 2, 1,850 seeds from 37 trees were analyzed in the same manner. The results
revealed that the maximum pollen dispersal distance in the two plots exceeded 25 m. Pollen dispersal appeared to be inversely
proportional to the distance from the marker tree. The effective pollen dispersal was suggested to be less than about 20 m
in a mature hinoki seed orchard. Adjacent trees had an excessive influence when the pollen density was increased by artificial
flower stimulation. Therefore, it was suggested that seed production better resembles ideal random mating when carried out
as naturally as possible. In conclusion, the SSCP chloroplast DNA marker was a useful tool for amassing basic information
on pollen management in seed orchards of coniferous species. 相似文献
18.
A model to predict the bending modulus of elasticity (MOE) of oriented strand board (OSB) panels produced by batch processing
is presented. The approach developed herein is unique in its comprehensiveness since the MOE is determined from information
on the panel structure, temperature and moisture profiles and vertical density profiles obtained from the mat formation and
compression models presented in Part 1. Comparison of predicted MOE values with those measured from 24 commercially produced
panels shows good agreement considering some of the uncertainties involved. Simulations show that the MOE can be increased
by any of the following changes: reduced fines content, increased panel density, better flake alignment in each of the three
layers within a panel, increased flake length and a larger difference between the density of the face and core layers. The
model was also used in a genetic algorithm to carry out an optimization study of batch OSB manufacturing. This analysis showed
that by combining the appropriate reduction in the amount of flakes used, increase in fines content, improvement in flake
alignment within each of the face and core layers and shortening of the batch time, a significant theoretical profit increase
from the base case scenario can be obtained. 相似文献
19.
Yoshio Kijidani Noriko Sakai Keita Kimura Yoshitake Fujisawa Yuichiro Hiraoka Junji Matsumura Shinya Koga 《Journal of Wood Science》2012,58(6):471-478
Hinoki (Chamaecyparis obtusa) wood has been used as a structural material in Japan because of its superior mechanical properties, its excellent durability and the beautiful color of its heartwood. Variations of termite resistance and compositions of extractives among hinoki trees have been reported. However, genetic variation of termite resistance and the effect of heartwood color on termite resistance remain unknown. In this study, we report the characteristics of termite resistance and color indexes (L*, a* and b*) of heartwood of hinoki half-sib families in a progeny test stand. The survival days of termites and the mass loss of samples of hinoki heartwood differed significantly among hinoki families. Families with red-color heartwood had larger termite resistance than families with yellow-color heartwood. The termite resistances of individual samples from two families with yellow-color heartwood were as small as that of Pinus densiflora. Larger a* and smaller b* induced larger termite resistance of heartwood. The effect of DBH (diameter at breast height) of hinoki trees on termite resistance of hinoki families was small. 相似文献
20.
The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black
spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different
refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either
0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical
blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters.
Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was
used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship
between panel properties and the two test factors. The results from this study indicated that the preheating retention time
was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant
factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water
absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure.
Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m3 had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark
residues can be considered as a potentially suitable raw material for manufacturing MDF products. 相似文献