• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.156-167
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• 2015

The aim of this study was to determine the physical and mechanical properties of glued laminated timber (glulam) manufactured from small-diameter logs of three wood species, Acacia mangium (mangium), Maesopsis eminii (manii), and Falcataria moluccana (sengon), with densities of 533, 392, and $271kg/m^3$, respectively. Glulam measuring 5 cm by 7 cm by 160 cm in thickness, width, and length, respectively, was made with three to five lamina, or layers, and isocyanate adhesive. The glulams contained either the same wood species for all layers or a combination of mangium face and back layers with a core layer of manii or sengon. Solid wood samples of the same size for all three species were included as a basis for comparison. Physical-mechanical properties and delamination tests of glulam referred to JAS 234:2003. The results showed that the properties of same species glulam did not differ from those of solid wood, with the exception of the shear strength of glulam being lower than that of solid wood. Wood species affected glulam properties, but three- and five-layer glulams were not different except for the modulus of elasticity. All glulams were resistant to delamination by immersion in both cold and boiling water. The glulams that successfully met the JAS standard were three- and five-layer mangium, five-layer manii, and five-layer mangium-manii glulams.

• Journal of the Korean Wood Science and Technology
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• 제43권6호
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• pp.714-720
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• 2015

목재의 물리, 역학적 특성은 토양, 기후변화 등의 환경적 인자뿐만 아니라 임분특성에 의해서도 바뀌게 되므로 남부 세 지역의 임분특성이 목재의 재질특성에 미치는 영향과 지역별 물리, 역학적 특성 등을 비교 검토하였다. 전남, 제주도의 구실잣밤나무 임지에 대하여 임분특성과 목재재질특성을 평가 분석하였는데 이들 간에는 대부분 높은 상관관계가 나타났다. 구실잣밤나무의 기건밀도의 물리적 특성과 휨, 압축, 전단강도의 역학적 특성은 임분 특성에서 흉고직경과는 부의 상관관계를 나타내었고 표고, 배수와는 정의 상관관계를 나타내었으며 모든 부분에서 유의성이 나타났다. 또한 물리 역학적 특성에서도 지역별로 차이가 나타났다. 본 연구의 목재 재질특성 분석결과, 남부지역의 구실잣밤나무는 난대 지역의 유용한 산림자원으로 활용할 수 있을 것으로 생각된다.

• International Journal of Concrete Structures and Materials
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• 제9권2호
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• pp.219-239
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• 2015

This paper discusses the suitability of producing concrete with 100 % recycled aggregate to meet durability and strength requirements for different applications. Aggregate strength, gradation, absorption, specific gravity, shape and texture are some of the physical and mechanical characteristics that contribute to the strength and durability of concrete. In general, the quality of recycled aggregate depends on the loading and exposure conditions of the demolished structures. Therefore, the experimental program was focused on the evaluation of physical and mechanical properties of the recycled aggregate over a period of 6 months. In addition, concrete properties produced with fine and coarse recycled aggregate were evaluated. Several concrete mixes were prepared with 100 % recycled aggregates and the results were compared to that of a control mix. SEM was conducted to examine the microstructure of selected mixes. The results showed that concrete with acceptable strength and durability could be produced if high packing density is achieved.

• 폴리머
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• 제38권2호
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• pp.129-137
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• 2014

본 연구에서는 재활용 폴리프로필렌을 첨가한 wood plastic composite(WPC)의 물성을 극대화하기 위해 먼저 용융혼합 조건을 최적화하였으며 재활용 폴리프로필렌의 함량이 WPC의 물성에 미치는 영향을 조사하였다. WPC의 기계적 특성을 측정하기 위해 만능재료시험기와 충격시험기를 사용하였고 열적 특성을 조사하기 위해 DSC, TGA, DMA를 사용하였다. SEM을 이용하여 WPC의 파단면을 관찰하였다. 전체 폴리프로필렌 함량의 50 wt%를 재활용 폴리프로필렌으로 함유한 WPC의 최적가공 조건은 $170^{\circ}C$, 15분, 60 rpm이었다. 재활용 폴리프로필렌의 함량증가는 WPC의 수분흡수성을 증가시켰고 열적, 기계적 특성을 저하시켰다. 그러나 모든 물성을 종합하여 분석한 결과 WPC의 두드러진 물성 감소 없이 전체 폴리프로필렌 함량의 50 wt%까지 재활용 폴리프로필렌을 첨가하는 것이 가능하였다.

• Advances in concrete construction
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• 제16권6호
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• pp.291-302
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• 2023

As the first part of the body that strikes the ground during running, sports shoes are especially important for improving performance and reducing injuries. The use of new nanotechnology materials in the shoe's sole that can affect the movement angle of the foot and the ground reaction forces during running has not been reported yet. It is important to consider the material of the sole of the shoe since it determines the long-term performance of sports shoes, including their comfort while walking, running, and jumping. Running performance can be improved by polymer foam that provides good support with low energy dissipation (low energy dissipation). Running shoes have a midsole made of ethylene propylene copolymer (EPP) foam. The mechanical properties of EPP foam are, however, low. To improve the mechanical performance of EPP, conventional mineral fillers are commonly used, but these fillers sacrifice energy return. In this study, to improve the magnificence of physical education training with nanotechnology, carbon nanotubes (CNTs) derived from recycled plastics were prepared by catalytic chemical vapor deposition and used as nucleating and reinforcing agents. As a result of the results, the physical, mechanical, and dynamic response properties of EPP foam combined with CNT and zinc oxide nanoparticles were significantly improved. When CNT was added to the nanocomposites with a weight percentage of less than 0.5 wt%, the wear resistance, physical properties, dynamic stiffness, compressive strength, and rebound properties of EPP foams were significantly improved.

• 대한기계학회논문집A
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• 제22권4호
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• pp.801-810
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• 1998

Modeling and analysis of dynamic systems generally demand their resutls to be interpreted each other with a physical sense. It sometimes requires that there should exist a unified tool in the treatment of dynamic systems which can be applied to both their modeling and analysis equally. This paper shows how models just after the progress of modeling via bond graph standards are converted to ones which are appropriate for analyzing a dynamic system in the frequency domain. Four bond graph prototypes are introduced to obtain frequency properties of dynamic systems such as zero stability, relative order, zero and pole dynamics, etc. directly from bond graphs, and the method are proposed which reduces nearly all models of bond graph standards to one of the prototypes without any change of physical similarity. This procedure as a tool for the structural reduction of bond graphs and finding frequency properties of a dynamic system is further investigated to survey its effectiveness through an example.

• 한국지반공학회논문집
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• 제30권11호
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• pp.39-49
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• 2014

제주도의 화산암은 여러 환경적인 요인으로 인하여 크기와 분포가 다양한 기공이 많은 다공상 구조를 보이고 있으며, 지질학적 그리고 역학적 특성 또한 지역마다 차이를 나타내고 있다. 제주도 화산암에 대한 지질학적/화학적 특성에 대한 연구 및 물리적/역학적 특성에 대한 연구는 많은 연구자에 의해 활발히 이루어져 왔지만, 제주도 화산암의 물리적 및 역학적 특성에 대한 종합적인 비교 분석은 이루어져 있지 않다. 본 연구에서는 제주도 화산암에 대하여 기존에 발표된 연구논문 및 보고서를 통하여, 제주도 화산암에 대한 물리 역학적 특성의 상관관계를 종합적으로 비교 분석하였다. 그 결과 흡수율 및 공극률과 겉보기 비중과의 관계는 일반적으로 선형의 관계에 있으며, 여러 환경적 요인에 의해 제주도 화산암은 두 개의 서로 다른 선형근사로 대표시킬 수 있음을 알 수 있었다. 그리고 P파 속도와 S파 속도와의 관계와 흡수율 및 공극률과 건조 상태의 암석에 대한 일축압축강도와의 각각의 관계에 대하여 흡수율 및 공극률과 겉보기 비중과의 두 개의 서로 다른 선형근사 관계를 고려함으로서, P파 속도와 S파 속도와의 관계와 흡수율 및 공극률과 일축압축강도와의 관계를 명확하게 구분할 수 있음을 알 수 있었다.

• Journal of the Korean Wood Science and Technology
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• 제44권2호
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• pp.172-183
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• 2016

Densification of the inner part of oil palm trunk (OPT) by the close system compression (CSC) method was performed in this study. The effects of the compression temperature and time on the anatomical, physical and mechanical properties of OPT were evaluated. The inner part of OPT with an initial average density of $0.3g/cm^3$ was used as samples. Oven-dried samples were immersed in water and vacuumed until fully saturated and then compressed by CSC at 120, 140, 160 or $180^{\circ}C$ for 10, 20, 30 or 40 min. The anatomical characteristics of transverse and radial sections before and after compression were compared by optical microscopy. The physical and mechanical properties, including the density, recovery of set (RS), modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain were examined. It was observed that the anatomical characteristic of the inner part of OPT (i.e., vascular bundles, vessels, and parenchyma tissue) became flattened, fractured, and collapsed after compression by CSC. The RS decreased with increasing compression temperature and time. The lower RS indicated high dimensional stability. The physical and mechanical properties (i.e., density, MOR, MOE, and compressive strength) of the inner part of OPT increased with increasing compression temperature and time. Compression by the CSC method at $160^{\circ}C$ for 40 min was the optimum treatment.

• Journal of the Korean Wood Science and Technology
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• 제16권3호
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• pp.22-37
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• 1988

In tendancy of manufacturing beam with laminating particleboard, it was thought that if the properties, especially mechanical properties, of particleboard be reinforced, the mechanical properties of particleboard-laminated beam would be also improved. So in this study the particleboard was reinforced with composing of wood particle and steel wire. This study was carried out to obtain the basic physical and mechanical properties of board composed of wood particle and steel wire, especially tensile strength and compressive strength which are the important factors of the lamina of beam, in order to estimate whether the board, composed of wood particle and steel wire could be to improve the properties of the particleboard- laminated beam. The results obtained were summarized as follows: 1. The board composed of wood particle and steel wire in accordance with lower board density took better thickness swelling. 2. The board with lower board density was improved in higher value of tensile strength with more steel wires in prescribed cross section area of the board. for example, the board of density 0.5 showing 140% improved value. 3. In compressive strength, the board with lower board density was also improved in hjgher value with more steel wires in prescribed cross section area.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.336-341
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• 1998

Steel fiber reinforced concrete(SFRC) is a composite material possessing many physical and mechanical properties which are distinct from unreinforced concrete. The use of steel fiber reinforcement to improve the flexural and tensile strengths, extensibility and toughness of ordinary cement concrete is well known at present, but reinforcement of polymer concrete with steel fibers has been hardly reported untill now. The objective of this study was to improve the properties of the polymer concrete by addition of steel fibers. In this paper steel fiber reinforced polymer concrete is prepared with various steel fiber contents and aspect ratio($\ell$ /d), and their mechanical properties were investigated experimentally.