Earticle

This research evaluated the effect of strand pretreatment and strand mixture ratio on the properties of Dual-Species Bamboo Oriented Strand Board (DS-BOSB) from andong and tali bamboo. Andong and tali bamboo strands were steamed at 126 °C for 1 hour under 0.14 MPa pressure and followed by rinsing by 1% NaOH solution. The two types of strands were then mixed by the ratio of 100:0, 75:25, 50:50, 25:75, and 0:100 for andong and tali strand respectively. Three layered DS-BOSB was made with 0.7 g/cm3 target density and 8% phenol formaldehyde adhesive content. The shelling ratio of boards was 25:50:25 with the size of (30x30x0.9) cm3. The measurement of physical and mechanical properties for DS-BOSB evaluation referred to the JIS A 5908 (2003) standard and the results were compared with the CSA 0437.0 (Grade O-1) standard. The results showed that the steam-treated followed by 1% NaOH rinse on the strand increased the dimensional stability and mechanical strength (internal bond) of DS-BOSB. The higher ratio of tali bamboo improved the dimensional stability and internal bonding of DS-BOSB. The optimal mixture ratio to produce OSB from andong and tali bamboo were 50:50. All OSBs meet CSA 0437.0 (Grade O-1) standard.

Fast-grown wood generally contains a high proportion of juvenile wood that results in inferior dimensional stability and durability against biological deteriorations. In the present research, the Acacia mangium wood from plantation forests in Vietnam was treated with high temperature in air. The effects of heat treatment on physical properties of Acacia mangium wood, including mass loss (ML), water absorption (WA), water-repellent effectiveness (WRE) and anti-swelling efficiency (ASE) were examined. The results showed that the dimensional stability and the water-repellent effectiveness are increased by about 15-46% and 8-18%, respectively. However, the mass and dimension of wood are decreased. The results also indicated that both treatment temperature and treatment duration significantly affect the wood properties of Acacia mangium. It is thus concluded that heat treatment demonstrates an interesting potential to improve the wood quality of Acacia mangium for solid timber products. This technology provides an environmentally safe method of protecting sustainable common woods to give a new generation of value-added biomaterials with increased stability without the use of toxic chemicals.

South Korea's territory is approximately 62% forested, and urban residential development near mountainous areas has become inevitable. However, localized heavy rainfall from climate change and increased forest destruction have led to a rise in sediment-related disasters in urban mountainous regions. To prevent such disasters, the Korea Forest Service developed a landslide hazard map, but it tends to overestimate risks on steep slopes, showing limitations in accurately predicting landslide occurrences. This study focuses on the Bangbae-dong area in Seoul, where debris flow damage occurred in August 2022. Using a digital terrain model, SINMAP, an infinite slope stability analysis method, was applied to predict landslide-prone areas. Subsequently, FLO-2D, a two-dimensional numerical model, was used to analyze debris flow behavior at locations identified as hazardous by SINMAP. The results classified the area as a slope-type debris flow region, with strong agreement between predicted hazard areas and actual debris flow events. Additionally, it was found that installing debris flow barriers at the affected sites could effectively block debris flows without overflow.

비교적 치수안정화 처리가 어려운 참나무과 고목재를 선택하여 락티톨, PEG (Mw, 4000), 슈크로오스를 이용하여 치수안정화효과에 대한 비교실험을 하였다. 시료 제작은 접선단면 판재 형태의 유물에서 굽음, 뒤틀림 등의 변형이 발생할 우려가 특히 크므로 접선단면이 넓게 나오도록 제작하였다. 보존처리약제의 처리농도는 10, 30, 50, 로 상승시켰고 각 농도단계별로 3일간, 7일간씩 처리하여 중량증가율을 측정하였다. 처리가 종료된 후의 시험편의 치수안정화효과를 평가하기 위한 지표로써 횡단면수축율을 산출하였다. 그 결과 슈크로오스를 함침처리한 시험편은 중량 증가율이 가장 높았으며, 횡단면수축율도 3일, 7일 처리에서 각각 로 가장 높은 치수안정화효과를 나타내었다.

The performance of dimensional stabilization of lactitol, PEG (Mw, 4000), and sucrose was evaluated for thin sections of oak wood (Quercus sp.) that had been buried in underground for presumably 1500 years. Thin wood sections of the specimen were soaked for three and seven days in each stabilizing agent with wide concentration ranges of 10, 30, 50, and by weight. Sucrose showed the largest weight gain among three agents, and the shrinkage of cross sections were found to be for three and seven days soaking, respectively. The result showed that sucrose among three stabilizing agents used was the best for the dimensional stabilization of the oak wood.

본 연구에서는 자연친화적인 호안 블록의 현장 적용시 충분한 기술적인 검증과 구조적, 수리학적 안정성 검 토 등이 제대로 이루어지지 않고 있는 문제점을 개선하기 위해 생태적 기능을 확보할 수 있는 식생강화를 위한 다공성 소일 블록에 대하여 수리적 거동 변화에 따른 수리학적 안정성을 검토하였다. 대상구간을 선정 하여 수치해석 및 수리모형실험을 실시하였으며 수치해석을 위해 1차원 수치해석모형인 HEC-RAS와 2차원 수치해석모형인 RMA-2를 이용하여 1, 2차원 수치해석을 실시하였고, Froude 상사법칙을 적용하여 식생 유, 무에 따른 축척된 수리모형실험을 실시하였다. 수리모형실험의 경우 실험결과에 대한 타당성을 위해 축척된 수리모형실험의 유속 및 소류력 결과를 원형으로 환산하여 1, 2차원 수치해석결과와 동일한 조건하에 비교· 검토하였고 그 결과 비교적 일치된 결과가 나타난 것으로 확인되었으며 이에 따른 원형으로 환산된 소류력 결과를 기존 연구결과인 호안의 허용소류력과 비교함으로써 블록의 수리학적 안정성을 제시하였다.

In this Research, in order to improve problems of not enough technical validation and structural and hydraulic stability evaluation when nature-friendly revetment block is applied to field, hydraulic stability evaluation according to hydraulic behavior change of porosity soil block for vegetation reinforcement that secures ecological function was reviewed. By selecting object section, numerical analysis and hydraulic model experiments were performed; for numerical analysis, by using 1-dimensional numerical analysis model HEC-RAS and 2-dimensional numerical analysis RMA-2, one-dimensional(1D) and two-dimensional(2D) numerical analysis were performed; by applying Froude's similarity law, reduced-scale hydraulic model experiments according to vegetation existence were performed. In hydraulic model experiment, for validity of experiment result, the result of velocity and tractive force of reduced-scale hydraulic model experiments was converted to prototype so that it can be compared and reviewed under the same condition of one-dimensional(1D) and two-dimensional(2D) numerical analysis result; as a result, it was confirmed that comparatively united result appeared, and by comparing prototype-converted tractive force result with revetment’s allowable tractive force coming from an existing research, block’s hydraulic stability was suggested.

For printed electronic paper making which is high leveled dimensional stability. The furnish which is hard wood pulp and soft wood pulp, mixed with hard and soft wood pulp is added sea algae pulp. If sea algae pulp was added 15% contents, paper which is made with hard wood pulp is increased about 28% dimensional stability and soft wood pulp is increased about 32%, dimensional stability and hard wood 30% and soft wood 70% mixed pulp is increased about 40% dimensional stability.

Purpose: The aim of study was to compare the dimensional stability of digitized dental stone replica using different color of gypsum materials using a white light scanner with three- dimensional software. Methods: A master model(500B-1, Nissin dental product, Japan) with the prepared lower full arch tooth was used. Several type stones(white, yellow, green) were used for 30 stone casts(10 casts each) duplicated a master model of mandible. The master model and the replicas were digitized with the non -contacting white light scanner to create 3-dimensional digital models. The linear distance between the reference points were measured and analyzed on the Delcam Copycad (Delcam plc, UK) 3D graphic software. One-way analysis of variance(ANOVA) combined with a Tukey multiple-range test were used to analysis the data( =0.05). Results: There were considerable differences in mean values between gypsum materials within each color(white, yellow, green), and this difference was statistically significant, p=0.001. Conclusion: Digitization of dental materials on optical scanner was affected by color. Three different color of gypsum materials showed clinically acceptable accuracies of full arch digital model produced by them. Besides, these results will have to be confirmed in further clinical studies.

석조문화재는 설계 도면이 소실된 경우가 많으며 정확한 형태정보가 없어 보존과 원형복원에 큰 어려움이 있다. 최근에 정밀실측과 같이 수치정보를 구축하는 연구가 활발히 진행되고 있지만, 대부분 2차원적으로서 활용도에 한계가 있다. 이를 보완하는 새로운 기법으로 3차원 영상 스캐닝 시스템이 도입되고 있다. 이 연구에서는 대원사다층석탑을 대상으로 3D 스캐닝을 통하여 3차원 영상분석과 자료를 구축하고 실측도를 작성하였으며, 이를 바탕으로 수 평 및 수직 변위를 평가하였다. 부재별 수치를 측정한 결과, 각 방면에서 서로 다른 수치를 보이고 있으며 상하 및 좌우변위가 나타났다. 수평적 상하변위는 좌면과 우면에서 탑신의 상부로 갈수록 컸으며, 수직적 좌우변위는 8층 옥개석이 북서쪽으로 치우쳐 있는 것으로 확인되었다. 이와 같은 변위측정과 평가는 석조문화재의 특성상 불균등한 표면과 프로그램 및 연구자에 따라 약간의 오차는 발생할 수 있다. 앞으로 다양한 실측과 안정성 평가연구가 진행된다면 석조문화재의 원형보존과 훼손상태 파악에 대한 정확한 자료를 제시할 수 있을 것이다.

A stone cultural heritage often lacks design drawing and detailed geometric informations, thus it becomes more difficult to conservation and restoration. Even though there is active database of detail shape information and numerical measurement for stone monuments, most of the data is in hard-to-utilize two-dimensional images. The new technology developed to overcome this problem is three-dimensional image scanning system. The multistoried stone pagoda of the Daewonsa temple was analysed with 3D scanning image data then survey map with orientation displacement was evaluated. The difference of each side became apparent with the members of the stone properties was measured, also horizontal and vertical displacement occurred. Horizontal displacement occurred in increasing severity from left to right and from body section to upper part. The 8th roof stones are leaning toward northwest direction due to lateral displacement. The evaluation and measurement of displacement could cause a little errors due to the characteristics uneven surface of stone monuments, computer program and mistakes from the researcher. In future, more precise measurement and stability studies should be done to suggest that accurate data for conservation and understanding of damage condition can be provided.

Purpose: This study aimed to evaluate the effect of postcuring conditions, such as variations in light intensity and curing time, on the color stability of resins used in three-dimensional (3D)-printed dental restorations. Methods: Using an liquid crystal display 3D printer, 81 specimens in the shape of a 10.0 mm×1.5 mm disk were produced according to the specified parameters. The printed specimens were postcured at various light intensities (17.76, 121.43, and 199.99 mW/cm2) and curing times (5, 10, and 20 minutes). Color was assessed using a color difference spectrophotometer (CM-3600A, Konica Minolta) based on the Lab* color space defined by the International Commission on Illumination, and the L*, a*, b*, C*, and H values and ΔE00 were analyzed. To evaluate the effect of postcuring conditions on the color changes, a twoway analysis of variance was conducted. Tukey’s post hoc test (α=0.05) was performed to assess significant differences. Results: The results showed significant differences in L*, a*, and ΔE00 values based on light exposure and curing time (p<0.001), whereas b* and C* values differed significantly (p<0.05). H values were not significantly different (p=0.231). Conclusion: This study demonstrated that light exposure and curing time significantly influenced the color stability of 3D-printed resin restorations. Thus, light exposure of Lv7 or lower and curing times of ≤10 minutes are recommended for optimal color stability.

Dimensional changes of single jersey fabrics made from $LincLITE^{(R)}$ and conventional yarns(39 tex and 48 tex) with different twist factors and fabric tightness factors are investigated under dry-, steam- and full- relaxation treatments. Results showed that linear and area shrinkages, fabric density and stitch density values were affected by tightness factors, relaxation treatment, yarn twist and feeder blending. Generally, higher length shrinkages and width increases were reported with $LincLITE^{(R)}$ and conventional fabrics. Tightness factors and twist factors significantly affected $LincLITE^{(R)}$ and insignificantly affected conventional fabrics in concern of change of shape and area shrinkages. Thus, fabric density values and reciprocal of stitch lengths showed linear correlations with intercepts, which decreased on full relaxation. Also, it showed higher regression correlation coefficient factors from $LincLITE^{(R)}$ and conventional fabrics.

Purpose : This study sought to evaluate the dimensional stability of the SITT (Silicone Index Tooth Tray) impression system and to determine whether providing space for wash impression material in SITT is a necessary step in obtaining accurate prostheses. Materials and methods : After mounting metal dies with shoulder and chamfer margins arbitrarily, SITT was fabricated using Blu-mousse$^{(R)}$. To test the dimensional stability of the SITT system for margin design, the shoulder margin and chamfer margin were evaluated. Furthermore, to test the effect of space for wash impression material, 0.5mm space in SITT and zero space in SITT were statistically compared. Results : 1. There was no significant difference between the group with shoulder margin and that with chamfer margin. 2. There was no significant difference between the group with 0.5mm space and that with zero space for wash impression material. Conclusions : Considering the limitations of this study, the dimensional stability of the SITT system did not interfere with the margin design. Space for the wash impression material was also unnecessary.

In this study, dimensional characteristics of core spun cotton/spandex interlock structures with high, medium and low tightness factors were studied under dry-, wet-, and full relaxation conditions. Results are compared with those for similar fabrics knitted from 100% cotton. Dimensional characteristics of samples of core-spun cotton/spandex and cotton are measured by considering the changing of course-, wale- densities and stitch densities under dry, wet and full relaxation conditions. Based on these data, dimensional constants(U-values) were predicted under 95% significance level. Higher U-values are reported with cotton/spandex interlocks than 100% cotton and under full relaxation, cotton/spandex shows the U-values with lesser CV%. Stitch density growth is linearly correlated with tightness factor for both interlock material structures. Excellent resiliency property of cotton/spandex yarns increases tightness factors at machine off state and during relaxation states. Cotton/spandex interlock structures show more prominent co-relationship with their tightness factors on their dimensional parameters.

Coffee chaff for manufacturing of the 6 mm thick cement-bonded boards was obtained from a coffee processing industry at Omuo-Ekiti, in Ekiti State, Nigeria. Boards were produced with three levels of cement to coffee chaff ratio of 1.5:1, 2.5:1 and 3.5:1; and at three levels of mixing curing reagent of 2.0%, 2.5% and 3.0%. Three dimensional properties of thickness swelling (TS), water absorption (WA) and linear expansion (LE) were investigated after 48 hours immersion in water. The mean values obtained for TS, WA and LE ranged from 0.46% to 1.47%, from 11.52% to 24.00%, from 0.19% to 0.35%, respectively. The most dimensionally stable boards were produced at the highest mixing levels of curing reagent and cement to coffee chaff ratio of 3.0% and 3.5:1, respectively. The coffee chaff is suitable as raw material for the manufacture of cement-bonded composites and it would be able to stimulate and activate the use of other agro-byproducts for the manufacture of value-added panels.

Dimensional constants (k values) of single jersey fabrics made from $LincLITE^{(R)}$ and conventional yams are calculated under dry, steam, full relaxation treatments. Fabrics were made under different tightness factors such as high, medium and low with different twist factors, twist directions and feeder blending. $LincLITE^{(R)}$ yarns made to get soft and bulkier effects with yam count of 39 tex and conventional yams made into 39 tex and 48 tex yam counts. Various effects on K values are analysed using correlation coefficients. K-values are increased with relaxation progression and have shown some differences between in $LincLITE^{(R)}$ and conventional fabrics, and feeder blended fabrics. Loop shape factor is highly affected by tightness factor, relaxation and feeder blending in $LincLITE^{(R)}$ fabrics, whereas twist factor not significantly effects on loop shape factor in conventional fabrics. Stitch density significantly increases with relaxation in conventional fabrics and no significant effect shows with $LincLITE^{(R)}$ fabrics.

This study was carried out to investigate the dimensional stability of bentwoods by three treatments: steaming, urethane varnish coating, and polyethylene glycol (PEG) treatment. Bentwood processing employed a bending-jig with only 4 cm radius of curvature (ROC). The used species were bitter wood (Picrasma quassioides), painted maple (Acer mono), and birch (Betula schmidtiii). The bending properties of these are well-known in bentwood production (Jung et al., 2002). The bentwoods were treated repeated at room temperature [20℃, RH 80% (12 hours) and 40℃ under RH 10% (12 hours)]. To estimate the dimensional stability of bentwoods, we measured the radius of curvature and end-distance. The best results could be attained with PEG treatment. Steaming was the worst treatment. Comparing the properties of the different species, the dimensional stability of bitter wood was excellent. It was concluded that the steaming treatment was unsuitable for dimensional stability of bentwoods.

Among the common textile fibers, wool has excellent wrinkle recovery. However, absorbed moisture plasticizes the structure and increases the rate of stress relaxation during wear deformation. Therefore, the wrinkle recovery of wool deteriorates under very high-humidity conditions and is of particular concern in men's lightweight suits, where the trend is toward wool fabrics of lightweight and bright color in which the wrinkles are emphasized. (omitted)

Thermo-mechanical treatment process of a compressed open-cell rigid polyurethane foam (OC-RPUF), which was fabricated for the vacuum insulation panel (VIP), was studied to obtain an optimum condition for the dimensional stability by the relaxation of compressive stress. Thermo-mechanical deformation of the sample OC-RPUF was shown to occur from about $120^{\circ}C$. Yield stress of 0.36 MPa was shown at about 10% yield strain. And, densification of the foam started to occur from 75% compressive strain and could be continued up to max. 90%. Compression set of the sample restored after initial compression to 90% at room temperature was ca. 82%. Though the expansion occurred to about twice of the originally compressed thickness in case of temperature rise to $130^{\circ}C$, it could be overcome and the dimensional stability could be maintained if the constant load of 0.3 MPa was applied. As the result, a thermo-mechanical treatment process, i.e, annealing process at temperature of $130{\sim}140^{\circ}C$ for about 20 min as is the maximum compressed state at room temperature, should be required for dimensional stability as an optimum condition for the use of VIP core material.

본 연구에서는 실제 의복 관리와 생산 면에서 접할 수 있는 모 직물의 접착심과의 접착 후, 프레싱 처리 후, 드라이클리닝 및 프레스로 처리 후 직물의 형태안정성과 의복형성능의 변화를 살펴보았다. 겉감으로는 신사복 춘하용 모 100% 또는 모 혼방 직물 15종류를 사용하였으며 심지로는 신사복에 많이 쓰이는 3종류 심지를 사용하였다. FAST시스템과 KES시스템을 이용하여 직물의 접착 후, 프레싱 처리 후, 드라이크리닝과 프레싱 처리 후의 형태안정성과 의복형성능의 변화를 시험하였으며 다음과 같은 결과를 얻었다. 1) 모직물의 형태안정성에서 주요인자인 습윤팽창(HE)은 접착으로 크게 감소하였고 프레싱 처리와 드라이크리닝과 프레싱 처리 후는 접착 후보다 큰 변화를 보이지 않는다. 모직물의 습윤팽창(HE)의 조절시 접착심이 습윤팽창(HE)의 안정성에서 중요한 역할을 하는 것으로 나타났다. 2) 완화수축(RS)은 접착 후 조금 감소하였으나 큰 변화를 보이지 않고 프레싱 처리 후 현저한 감소를 보인다. 드라이크리닝과 프레싱 처리 후는 직물이 수축하고 볼륨감이 생김으로 완화수축(RS)은 더욱 감소하였다. 모직물의 완화수축(RS)의 조절시 프레싱이 중요한 역할을 하는 것으로 나타났다. 3) 모직물의 의복형성능(TAV)은 접착으로 크게 향상되었다. 드라이크리닝과 프레싱 처리 후 직물이 좀더 부드러워지고 볼륨감이 생기면서 의복형성능(TAV)은 적게 향상됨을 보인다. 이와 같이 3가지 처리는 서로 보완되어 모직물의 형태안정성과 의복형성능을 향상시키는 것으로 나타났다.