• 한국의류산업학회지
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• 제10권3호
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• pp.377-384
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• 2008

For the purpose of standardization and practicability of natural dyeing, the mordanting and dyeing properties of gallnut was studied. In this study, the colorants of gallnut were extracted with boiling water. Chitosan crosslinked cotton fabrics were been dyed with aqueous extract of gallnut and their dyeabilities on the fabrics were studied. Additionally, the fastness to washing and light were also investigated. Cotton fabrics were treated with a crosslinking agent epichlorohydrin in the presence of chitosan to provide the cotton fabrics the dyeing properties of natural dye(gallnut) by the chemical linking of chitosan to the cellulose structure. The chitosan finishing and durable press finishing of the cotton fabrics carried out simultaneously in the mercerization bath. The dyeability(K/S), which was obtained by CCM observation, remarkably increased as the concentration of chitosan was high. Dye ability of gallnut showed higher toward chitosan treated cotton than controlled cotton fabric under condition at $60^{\circ}C$, for 20 min. The hue value indicated reddish yellow with increasing the crosslinked chitosan concentration. And the color fastness to washing and light was the almost the same.

• Tribology and Lubricants
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• 제35권1호
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• pp.24-29
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• 2019

In this work we investigated the friction and wear characteristics of a magnesium alloy, which has been receiving much attention as a light metal in industrial applications such as automobiles and aerospace. Magnesium is one of the lightest structural material that has high specific strength, lightweight, low density and good formability. However, current issue of using magnesium alloy is that magnesium has weakness against temperature. As the temperature increases, magnesium undergoes poor creep resistance and ease of softening, and therefore, its mechanical strength decreases sharply. To solve this issue, a new type of magnesium alloy that retains high strength at high temperature has been proposed. The tribological behavior of this alloy was investigated using a tribotester with reciprocating motion and heating plate. A stainless steel ball was used as a counter surface. Results showed that extrusion process has similar wear behavior to the commonly used casting process but retains good mechanical strength and durability. The presence of an alloying element enhanced the wear properties especially in high temperature. This study is expected to be utilized as fundamental data for the replacement of high density materials currently used in mechanical industries to a much lighter and durable heat-resistant materials.

• Journal of the Korean Wood Science and Technology
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• 제49권2호
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• pp.191-209
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• 2021

Australia has significant wood resources in its native forest, but the resource available for harvest becomes lesser due to the conversion of native forest to conservation reserves. The natural occurrences of bushfires, droughts, and cyclones are highly destructive, making the situation worse. The shortage of wood resources is having a significant negative impact on Australia because wood is so scarce that they cannot meet domestic demands, especially durable wood. Australia cleared approximately 100 million hectares of its land to establish forest plantations, and two million trees were planted. However, most of these plantations are for pulpwood production; however, their application for high-value products is limited due to their undesirable properties. Wood modification is a process of improving unfavorable wood properties to be utilized for a wide range of applications. Australia has not adopted any of these modification processes; it still depends on the less toxic wood preservative to treat wood. This study focuses on the recent advancement in industrial wood modification worldwide and how it may be used to modify Eucalyptus wood for high-value applications. The opportunities and suggestions for Eucalyptus wood modification in Australia will be discussed. Before the study concludes, the future of commercial wood modification for Eucalyptus plantation in Australia will also be presented.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.111-118
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• 2016

스케일링은 겨울철 제설제 살포 및 동결융해의 복합작용으로 인하여 교통시설 구조물에서 발생하는 대표적인 콘크리트의 성능저하 현상이다. 본 논문에서는 콘크리트의 스케일링 저항성에 영향을 미치는 요인을 분석하기 위하여 콘크리트의 역학적 성능, 공극구조 특성과 스케일링 저항성과의 관계를 실험적으로 고찰하였다. 실험결과, 콘크리트의 스케일링 저항성은 콘크리트의 압축강도와는 그다지 상관관계가 적었으며, 오히려 콘크리트의 표면투수 특성과 밀접한 관련이 있는 것으로 조사되었다. 또한, 콘크리트의 스케일링 저항성을 평가하기 위한 파라미터로써, 기포 간극계수 및 비표면적은 적합하지 않은 것으로 나타났다. 한편, 결합재의 종류에 따른 스케일링 저항성도 상이하게 나타났으며, 보통포틀랜드시멘트 콘크리트 및 실리카흄 콘크리트에 비하여 고로슬래그미분말을 사용한 콘크리트의 스케일링 저항성이 상대적으로 낮은 것으로 나타났다.

• 대한금속재료학회지
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• 제48권3호
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• pp.194-202
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• 2010

Application of a stronger and more durable material for reactor pressure vessels (RPVs) might be an effective way to insure the integrity and increase the efficiency of nuclear power plants. A series of research projects to apply the SA508 Gr.4 steel in ASME code to RPVs are in progress because of its excellent strength and durability compared to commercial RPV steel (SA508 Gr.3 steel). In this study, the microstructural characteristics and mechanical properties of SA508 Gr.3 Mn-Mo-Ni low alloy steel and SA508 Gr.4N Ni-Mo-Cr low alloy steel were investigated. The differences in the stable phases between these two low alloy steels were evaluated by means of a thermodynamic calculation using ThermoCalc. They were then compared to microstructural features and correlated with mechanical properties. Mn-Mo-Ni low alloy steel shows the upper bainite structure that has coarse cementite in the lath boundaries. However, Ni-Mo-Cr low alloy steel shows the mixture of lower bainite and tempered martensite structure that homogeneously precipitates the small carbides such as $M_{23}C_6$ and $M_7C_3$ due to an increase of hardenability and Cr addition. In the mechanical properties, Ni-Mo-Cr low alloy steel has higher strength and toughness than Mn-Mo-Ni low alloy steel. Ni and Cr additions increase the strength by solid solution hardening. In addition, microstructural changes from upper bainite to tempered martensite improve the strength of the low alloy steel by grain refining effect, and the changes in the precipitation behavior by Cr addition improve the ductile-brittle transition behavior along with a toughening effect of Ni addition.

• 한국지반환경공학회 논문집
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• 제24권6호
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• pp.13-20
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• 2023

본 연구는 강섬유(SF) 혼입률에 따른 고유동 흙막이 벽체 재료(RWM)의 역학적 성능 및 내구성을 평가하기 위한 것으로써, 흙막이 벽체 재료의 재료분리저항성, 유동성, 연행공기량을 확보하기 위하여 적정량의 고성능감수제(SP), 공기연행제(AEA) 및 증점 안정화제(VMA)를 사용하였다. 흙막이 벽체 재료 경화체의 압축 및 쪼갬 인장강도를 소정의 재령에서 측정하였으며, 흙막이 벽체 재료의 역학적 성능은 표면전기저항성 및 흡수율 실험을 통하여 고찰하였다. 또, 염소이온 침투저항성 및 동결융해 저항성 실험을 통하여 흙막이 벽체 재료의 내구성능을 고찰하였다. 실험결과에 의하면, 강섬유를 적용한 배합이 강섬유 무혼입 배합에 비하여 우수한 성능을 나타내었으며, 2% 적용 배합이 경제성 및 성능 관점에서 상대적으로 효과적인 것으로 관찰되었다. 따라서, 적절한 SF의 적용은 흙막이 벽체 재료의 성능 향상에 기여할 것으로 판단된다.

• Elastomers and Composites
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• 제1권1호
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• pp.49-55
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• 1966

Based upon the results of the previous work, the experiments are concentrated on the improvement of the durability of rubber coated fabrics as a rain garment material. To obtain a much lighter and durable coated fabric, several kinds of light weight cotton prints having almost equal density in warp and fillingwise were chosen. Rubber coating on these prints was made by topping and spreading process using rubber compound of various viscosity, and the physical properties of final product were analysed and interpreted in terms of adhesion and durability. The results are as follows. 1. Any noticeable difference between two coating processes was not found in terms of physical properties. 2. Base fabrics should be dipped once into a dilute rubber compound before coating operation in order to obtain a uniform adhesion and physical properties, and the optimum range of the viscosity of dipping paste are from 100 poise to 200 poise. 3. Generally, the tearing strength of the coated fabrics is inversely proportional to the adhesion. 4. It was assumed that the increase of the water proofness after water immersion on the finished material which have dense base fabric is chiefly due to the swelling of the cellulosic fiber.

• 자원환경지질
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• 제35권4호
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• pp.347-353
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• 2002

현재 우리 나라에서 조리용구로 많이 사용되고 있는 석재에는 휘석암과 각력암, 흑운모섬록암 등이 있으며, 이중 유색광물이 상대적으로 많은 휘석암과 흑운모섬록암은 비중이 3.0으로 각력암(2.5)보다 약간 더 무거운 특징을 보였고, 흡수율은 각력암이 2.9%로 가장 높았으며, pH는 모두 9.7-9.9의 범위로 약알칼리성을 나타내었다. 또한 조리용구용 석재중 흑운모섬록암이 각력암이나 휘석암보다 마모에 대한 내구성과 강도가 가장 우수하석 다른 특별한 요인이 없는 한 가장 오랫동안 사용할 수 있음을 나타내었다. 용출시험 결과, Cu, Pb, Co, Cr Ni 등의 유독성 중금속 원소들은 연구대상 암석에서 모두 반응시간 및 용액의 초기 pH에 관계없이 모두 측정 한계값인 0.1 ppm 이하로 낮았으나, 철(Fe)은 암석의 종류 및 용출 조건에 따라 다소간의 용출량 차이를 보였는데, 대체로 중성보다는 산성용액을 첨가하였을 경우에 약 1.8-31배 정도 더 높은 용출량을 나타내었고, 반응용액이 중성인 조건에서는 각력암에서, 산성인 경우에는 흑운모섬록암에서 가장 높은 철(Fe)의 용출량을 보여 주었다. 석재를 인체에 해가 없는 고기능성 조리용구로 이용하기 위해서는 인체에 영향을 미칠 수 있는 중금속 및 다량 무기질 원소들에 대한 용출함량 기준이 먼저 마련되어야 하며, 또한 보다 많은 종류의 조리용구용 석재와 화학원소들을 대상으로 좀 더 체계적인 무기화학적 특성에 하한 연구가 필요할 것으로 생각한다.

• 보존과학회지
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• 제17권
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• pp.19-32
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• 2005

전통목조건축물의 단청에서 발생하는 도막의 박리현상을 개선시키기 위해, 목재의 친수성으로 인해 목재와 도막간의 팽윤수축률의 차이에 의해 발생되는 응력이 도막의 내후성에 미치는 영향을, 도막의 기계적 성질(인장성질과 응력완화)과 교착제(아교, 아크릴에멀젼(Primal AC-3444), 아크릴수지 (Paraloid B-72))에 의한 포수방법으로부터 평가하였다. 아크릴에멀젼 도막은, 아크릴에멀젼의 유리전이온도가 상온 이하$(7^{\circ}C)$로써 외력에 대한 응력완화가 큰 성질을 가지고 있기 때문에, 열화촉진실험과 옥외폭로실험에서 박리가 발생하지 않았으며, 다른 교착제를 사용한 도막에 비해 내후성이 가장 뛰어났다. 또 목재에 교착제를 저농도에서 고농도까지 중복칠하는 포수방법이 다른 포수방법들보다 도막의 내후성을 향상시키는 효과가 있었다.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.243-257
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• 2017

Investigating the properties and durability of high-strength concrete exposed to sulfuric acid attack for the purpose of its application in structures exposed to this acid is of outmost importance. In this research, the resistance and durability of high-strength concrete containing macro-polymeric or steel fibers together with the pozzolans of silica fume or nano-silica against sulfuric acid attack are explored. To accomplish this goal, in total, 108 high-strength concrete specimens were made with 9 different mix designs containing macro-polymeric and steel fibers at the volume fractions of 0.5, 0.75, and 1.0%, as well as the pozzolans of silica fume and nano-silica with the replacement levels of 10 and 2%, respectively. After placing the specimens inside a 5% sulfuric acid solution in the periods of 7, 21, and 63 days of immersion, the effect of adding the fibers and pozzolans on the compressive properties, ultrasonic pulse velocity (UPV), and weight loss of high-strength concrete was investigated and the respective results were compared with those of the reference specimens. The obtained results suggest the dependency of the resistance and durability loss of high-strength concrete against sulfuric acid attack to the properties of fibers as well as their fraction in concrete volume. Moreover, compared with using nano-silica, using silica fume in the fibrous concrete mix leads to more durable specimens against sulfuric acid attack. Finally, an optimum solution for the design parameters where the crushing load of high-strength fibrous concrete is maximized was found using response surface method (RSM).