PURPOSES : This study describes the experimental findings on the mechanical properties of calcium aluminate cement (CAC)-based repair mortars with or without natural cellulose fiber (NCF). Additionally, the effect of adding NCF to the reduction of fugitive dust in the CAC powder was examined. METHODS : To produce mortar, four different levels of NCF (0.0.5, 1.0, and 2.0% by binder weight) were adopted, and the water-binder ratio was fixed at 0.485. The flow, strength characteristics, absorption, and surface electrical resistivity of the mortars were measured at predetermined periods. Additionally, SEM observations were performed to examine the microstructural changes and hydrates formed on the 28 day-mortar samples. RESULTS : The addition of NCF led to a decrease in fugitive dust. Regarding the mechanical properties of the mortars, that with 0.5% NCF exhibited a better performance in terms of strength development and surface electric resistivity compared to those of other mortars. However, the addition of NCF was less effective in the enhancement of the absorption of mortars. Further, we discovered that the microstructures of the mortars with additional NCF were comparatively dense compared to those without NCF. CONCLUSIONS : The appropriate addition of NCF can enhance the performance of CAC-based repair materials. However, further studies on the durability of CAC with the addition of NCF are needed to determine the optimal mixture.

In the present paper, the natural fiber materials that can be replaced to reduce the weight of the vehicle are analyzed by bubble charts of - and - , and the possibility of alternative application of materials is investigated. For this purpose, the driving energy and fuel efficiency of the vehicle using the data of K model analyzed. In addition, the effect of vehicle weight on fuel efficiency was analyzed through the dynamic analysis approach of the vehicle. From the research results, the following results were obtained. Most of natural fibers have lower density and equal tensile strength and strain than metal materials. Therefore, the application rate of natural fiber materials should be increased in consideration of the application purpose and material characteristics of the vehicle. The major variables that greatly influence driving energy and fuel efficiency were fuel efficiency improvement of about 10% in order of speed, rolling resistance and mass. In addition, when steel is lightened by 10%, fuel efficiency improvement of up to maximum 4.5% is shown in the order of CFRP, Al, Ti.

본 연구에서는 인체 친화적이고 환경 친화적인 패션제품 소재기획을 위한 기초 자료를 제시하고자 수행되었다. 이를 위해서 4종의 섬유소 소재를 대상으로 염색조건을 달리하여 천연 쪽 염색을 실시하여 색채특성과 색채감성을 평가하였으며, 이러한 특성이 선호도에 미치는 영향을 분석하였다. 쪽 염색된 직물은 모두 중, 저명도와 저채도의 남색(PB)을 구현하였다. 이들 직물의 색채특성은 섬유종류와 염색조건에 따라 유의한 차이를 보였다. 쪽 염색된 직물에 대한 색채감성은 스포티 감성, 클래식 감성, 내추럴 감성 등 3가지 요인으로 분류되었다. 이러한 색채감성은 섬유종류와 염색조건에 따라 부분적으로 유의한 차이를 나타내었다. 또한 쪽 염색 직물의 색채특성과 색채감성 요인 간에는 부분적으로 유의한 상관관계를 보였다. 쪽 염색 직물의 색채 선호도에 영향을 주는 요인으로는 색채감성 요인 중에서 클래식 감성과 스포티 감성, 색채특성에서는 L*값인 것으로 나타났다.

The purpose of this research is to revive the colors of combination dyeing and mixed dyeing with natural dyestuffs. The fabrics used were cotton and rayon. The natural dyestuffs used in this research were indigo, Phellodendron amurense, and Caesalpinia sappan. The effects of combination dyeing were as follows. First, all samples showed deeper colors. Second, according to the results of the surface K/S measurement, while the surface K/S of cotton was over 15, that of rayon was over 17. Third, the results of the light fastness measurement showed the superiority (by over grade 4) of all the samples, except in the case of rayon fiber sample no. 6 (which had been pre-dyed with indigo five times before being dyed with P. amurense once and then being dyed with C. sappan once). In the color fastness to washing measurement, all fibers showed superiority (by over grade 3~4). In addition, the color fastness to dry cleaning of all fibers was satisfactory or excellent (by over grade 3). Fourth, according to the results of the tensile strength measurement, it tended to decrease in the case of cotton and increase in the case of rayon. Fifth, the results of the density measurement showed that the density of cotton decreased by about 15~20% in the case of warp and 10% in the case of weft for all samples. The density of rayon decreased 20% in the case of warp for all samples and increased 30% in the case of weft for all samples.

전 세계적으로 ‘지구환경 보호운동’과 웰빙 삶이 확산되면서 환경과 인체에 부정적인 영향을 미치고 있고, 특히 합성섬유의 주원료인 원유가 멀지 않은 장래에 고갈될 것을 예상하고 있으며, 이에 대한 대안으로 새로운 천연섬유 소재의 창출에 대한 연구가 활발하게 진행되고 있다. 따라서 본 연구는 천연섬유의 주산지가 될 수 있는 자연 환경적 요소를 갖추고있는 캄보디아 천연섬유 작물 현황을 조사하여 추후 한국 농산업체의 천연섬유 생산에 대한 투자를 대비한 정보를 제공하고자 조사 연구하였던 바 결과를 요약하면 다음과 같다. 1. 현재 캄보디아의 천연섬유산업은 소규모로 아직 초기 단계에 있으며, 조사된 황마, 부레옥잠 등 열대식물도 있지만, 왕골, 갈대, 목화 등 온대지역에 자생하는 천연섬유 등 12가지 작물이 대표적인 천연섬유 작물로 조사되었다. 2. 누에를 이용한 실크산업은 캄보디아의 저렴한 노동임금으로 부가가치 창출이 쉬운 산업으로 캄보디아 정부에서 활성화 길을 모색하고 있으나, 기술력 향상을 위한 인력양성이 가장 큰 문제점으로 대두되고 있다. 3. 목화를 이용한 천연섬유 생산은 대단위 노동집약적 산업으로 수출활로의 전망은 좋으나 주로 북부지역이 주 생산지로 인구밀도가 적은 농촌지역에서 활성화시키는데 한계점이 있는것으로 나타났다. 4. 캄보디아의 열대성기후와 정부의 지원, 세계의 천연섬유산업의 트렌드와 더불어 천연섬유 분야의 전문가 양성과 해외 투자자유치, 섬유생산기술 발전 등을 동반한다면 캄보디아는 새로운 천연섬유생산기지로 발전 가능성이 있는 것으로 조사되었다.

The purpose of this paper is to detect the fiber stiffness degradation of GFRP plates from natural frequency response data. The combined finite element analysis using ABAQUS program and the inverse algorithm described in this paper may allow us not only to detect the deteriorated elements from the mirco mechanical point of view. Several numerical results show that the proposed system is computationally efficient in identifying fiber stiffness degradation for complex structures such as composites.

An experiment to understand how natural fiber reinforcement would influence rammed earth P-δ curves was conducted. The experiment results showed that the natural fiber reinforcement had generally increased loads of specimens and that the longer the fibers and the higher the mixing ratios, the lpad degradation after failures tend to be slowly appeared.

It was indicated that natural fiber crops Ln Korea have been major crops, such as cotton, flax, ramie and Kenaf. The major varieties andagronomic characterics are summarized as follows. Cotton variety, Mokpo 6 is long fiber length and, is high lint yield, flax variety, Wiera is hiTh amount of dry stem and grains weiTht. On the other hand, kenaf variety, Suweon 2 is high dry fiber weight and fiher ratio.