• Geomechanics and Engineering
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• 제6권1호
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• pp.33-45
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• 2014

Use of geotextile as reinforcement material to improve the weak soil is a popular method these days. Tensile strength of geotextile and the soil-geotextile interaction are the major factors which influence the improvement of the soil. Change in fine content within the sand can change the interface behavior between soil and geotextile. In the present paper, the bearing capacity of unreinforced and geotextile-reinforced sand with different percentages of fines has been studied. A series of model tests have been carried out and the load settlement curves are obtained. The ultimate load carrying capacity of unreinforced and reinforced sand with different percentages of fines is compared. The interface behavior of sand and geotextile with various percentages of fines is also studied. It is observed that sand having around 5% of fine is suitable or permissible for bearing capacity improvement due to the application of geosynthetic reinforcement. The effectiveness of the reinforcement in load carrying capacity improvement decreases due to the addition of excessive amount of fines.

• Carbon letters
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• 제13권2호
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• pp.88-93
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• 2012

Polypyrrole (PPy)/multi-walled carbon nanotubes (MWCNTs) composites were prepared by in situ polymerization of pyrrole on the surface of MWCNTs templates to improve the ammonia gas sensing properties. PPy morphologies, formed on the surface of MWCNTs, were investigated by field emission scanning electron microscopy. The thermal stabilities of the PPy/MWCNTs composites were improved as the content of MWCNTs increased due to the higher thermal stability of the MWCNTs. PPy/MWCNTs composites showed synergistic effects in improving the ammonia gas sensing properties, attributed to the combination of efficient electron transfer between PPy/MWCNTs composites and ammonia gas, and the reproducible electrical resistance variation on PPy during the gas sensing process.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.235-236
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• 2011

This study analyzed flowing and strength properties of mortar depending to fine aggregate types and replacement ratio by using blast furnace slag, red mud, and silica fume that are industrial by products. The findings showed that higher replacement level of fine aggregate increased air content while decreased table flow. In addition, compressive strength showed that the higher replacement level was regardless of fine aggregate types, the lower strength became. Mortar substituted by the dredged sand showed high strength.

• Journal of Korean Society for Atmospheric Environment
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• 제21권E2호
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• pp.67-74
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• 2005

Domestic anthracite contains a large amount of fine particles, which causes to fire the back side of the boiler and to form the clinker deteriorating the combustion efficiency. At this time, the fine limestone adsorbents for a desulphurization agent may be used to facilitate an aggravation of the boiler, so that fine mode of limestone (<0.1mm) has been used no more than $25\%$ in local power stations of Korea. The present test carried out with an in-situ boiler, however, showed that higher content $(up\;to\;50\%)$ of fine limestone particles did not entail any mal-function. In addition, the desulphurization was found to be as good as the old mode of limestone adsorbents.

• 한국세라믹학회지
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• 제43권4호
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• pp.213-219
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• 2006

A Monte Carlo simulation based on Potts model in a three dimensional lattice was studied to analyze and design microstructures in porous sintered compacts such as porosity, pore size, grain (particle) size and contiguity of grains. The effect of surface energy of particles and the content of additional fine particles to coarse particles on microstructure development were examined to obtain fundamentals for material design in porous materials. It has been found that the larger surface energy enhances sintering (necking) of particles and increases contiguity and surface energy does not change pore size and grain size. The addition of fine particles also enhances sintering of particles and increases contiguity, but it has an effect on increment of pore size and grain size. Such a simulation technique can give us important information or wisdom for design of porous materials, e.g., material system with high surface energy and fine particle audition are available for higher strength and larger porosity in porous sintered compacts with applications in an automobile.

• 한국잠사곤충학회지
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• 제43권1호
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• pp.41-48
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• 2001

The purification, dissolution and powdering of stained waste silk obtained from weaving and dyeing process were studied for the surface modification of textile fabric and plastic materials. The whiteness of stained waste silk could be improved through degumming and bleaching with sodium hydrosulfite. The water-soluble fibroin solution can be obtained by dissoving the degummed waste silk in a boiling solution of 50% calcium chloride for 60 minutes. The salts and heavy metals contained in fibroin solution were removed by electric dialysis, wool fiber filtration and gel filtration chromatography. The fibroin powder was prepared by using a fine grinder after the alkali treatment for weakening the silk fiber. The fine fibroin powder of particle size around 30 ㎛ was obtained with a ultra fine-mill, while it was finer below 10 ㎛ with a ball-mill. The dissolved or powdered silk was applied to the surface of fabric with addition of the binder (a urethane resin). The moisture content of polyester and nylon fabrics treated with the silk solution was improved due to hygroscopic property of silk. The fine fibroin powder mixed with the binder ws coated on the surface of synthetic film by use of the air pressed sprayer. It was revealed that the hygroscopicity as well as the softness of fibroin powder coated film was much improved. Therefore, it is thought that the fine silk fibroin powder is applicable as an coating agent for the surface modification of plastic and synthetic leather.

• Advances in concrete construction
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• 제10권4호
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• pp.311-317
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• 2020

Performance of Sustainable materials continues through using of recycled waste construction materials to minimize the utilization of the natural resources. The cement industry is a major source of CO₂ in the atmosphere which is the main cause of global warming. Replacement of OPC with other sustainable cementitious materials has been the most interesting area of researches. This investigation focuses on the properties of alkali-activated mortar with the different replacement ratios of ceramic tile powder (CTP) by fine soil powder (FSP) (0 to 100)% and different molarities of sodium hydroxide concentrations. The experimental program was conducted by examining the compressive strength, water absorption, and water sorptivity. The results showed that the compressive strength of the specimens at age of (28, 56, and 90 days) increases with an increase in the amount of fine soil powder content and decreases at the age of 120 days. Also, minimum water absorption at the age of 90 days was found in the mixes containing 100% fine soil powder. However, fine soil powder replacement had a negative effect on the sorptivity and water absorption values at the age of 120 days. On the other hand, the 12M sodium hydroxide concentration was considered the optimum concentration compared to other concentrations.

• 대한건축학회논문집:구조계
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• 제36권1호
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• pp.155-162
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• 2020

The aim of the research is to investigate the fundamental properties and heat of hydration reducing performance of the fly ash incorporated concrete mixture when the coal gas slag (CGS) from integrated gasification combined cycle (IGCC) is used as fine aggregate. From the results of the experiment, the workability was generally increased and the air content was decreased up to one to four percent with increasing the replacing ratio of CGS to fine aggregate. The compressive strength was similar or increased within five percent to the Plain mixture when the CGS was used as a fine aggregate. When the CGS and fly ash were used same time, the heat of hydration reducing performance was improved than single using cases either CGS or fly ash. Based on the results, for the concrete mixture using CSG as a portion of the combined fine aggregate, the general properties were improved and heat of hydration was decreased approximately 16 % when the fly ash was replaced 30 % to cement and the CGS was replaced less than 50 % to fine aggregate.

• 대한수의학회지
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• 제31권1호
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• pp.109-121
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• 1991

소의 지방간(脂肪肝)의 이환율(罹患率)을 조사(調査)하고 fine needle aspiration biopsy에 의한 지방간(脂肪肝)의 세포학적진단(細胞學的診斷)을 시도(試圖)하였다. 육안적(肉眼的) 또는 부유법(浮遊法)에 의한 간장지방함량(肝臟脂肪含量)에 기초(基礎)한 소의 지방간(脂肪肝)의 발생율(發生率)은 한우(韓牛)암소에서 0.30%, 유우(乳牛)암소에서 4.70%, 유우(乳牛)숫소에서 0.15%였다. 지방간(脂肪肝)은 육안적(肉眼的) 소견(所見)으로 간장(肝臟)이 종대(腫大)되고 변연(邊緣)이 둔하며 가볍고 창백(蒼白)에서 주황색(朱黃色) 색조(色調)를 보이나 간장(肝臟)의 색조(色調)와 지방간(脂肪肝)의 중증도간(重症度間)에 환상(桓常) 상관관계(相關關係)가 인정(認定)되지는 않았다. 대부분의 정상간장(正常肝臟)과 중도(重度)의 지방간(脂肪肝)을 제외(除外)하고는 간장(肝臟)의 지방침윤(脂肪浸潤)은 중심정맥주위(中心靜脈周圍)에서는 거대지방구(巨大脂肪球)와 변연부(邊緣部)에서는 소지방구(小脂肪球) 그리고 맥관부(脈管部)에 지방침윤(脂肪浸潤)의 소견(所見)을 보였다. 부유법(浮遊法)에 의한 간장지방함량(肝臟脂肪含量)과 비교(比較)한 세포학상(細胞學上)의 민감도(敏感度), 특이도(特異度), 정확도(正確度)는 정상(正常)에서 94.4%, 95.2%, 94.9%, 경도(輕度)에서 64.3%, 100%, 87.2%, 중등도(中等度)에서 100%, 83.39%, 82.2%, 그리고 중도(重度)에서 모두 100%였다. 세포학적(細胞學的) 소견(所見)은 조직학적(組織學的) 소견(所見)과 잘 일치(一致)하였다. Fine needle aspiraton biopsy에 의한 합병증(合倂症)은 임상적(臨床的)으로 인지(認知)되지 않았다. 결론적(結論的)으로 needle aspiration biopsy에 의한 세포학적(細胞學的) 진단(診斷)은 소의 지방간(脂肪肝) 진단(診斷)에 있어서 조직학적(組織學的) 기법(技法)과 비교(比較)했을 때 단순(單純)하고 신속(迅速)하며 안전(安全)하며 경제적(經濟的)인 방법(方法)으로 사료(思料)된다.

• 콘크리트학회논문집
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• 제29권2호
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• pp.149-157
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• 2017

건설 폐기물 양이 증가하면서, 순환재료의 재사용은 건설 분야 중에서도 학문적으로 활발하게 연구되고 있는 분야로 자리 매김하고 있다. 이에 따라 순환재료를 사용한 모르타르 및 콘크리트 품질의 개선과 역학적 특성을 규명하고자 하는 연구는 활발하게 진행되고 있지만, 순환재료를 사용한 섬유보강 시멘트 복합체에 대한 연구는 많지 않다. 본 연구에서는 순환잔골재 및 플라이애시가 PVA 섬유보강 시멘트 복합체의 역학적 특성에 미치는 영향에 대해서 실험적으로 분석하고자 하였다. 순환잔골재 및 플라이애시 치환율은 25% 및 50%로 설정하였으며, 순환재료 치환율에 따른 10개의 PVA 섬유보강 시멘트 복합체의 휨, 압축 및 인장거동을 실험적으로 평가하였다. 실험결과 플라이애시 치환율이 증가함에 따라 휨, 압축, 직접인장강도가 감소하였다. 특히 순환잔골재 및 플라이애시를 각각 50% 치환하는 경우 강도가 가장 낮게 나타났다. 탄성계수는 재령 28일에서의 압축강도와 유사한 경향을 나타냈으며, 푸아송 비는 순환잔골재 및 플라이애시 치환율이 증가함에 따라 크게 나타났다.