• 한국농공학회지
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• 제44권4호
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• pp.123-128
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• 2002

This study was performed to use fiber mixed soil which has clayey soil or sandy soil with fibrillated fiber or monofilament fiber on purpose of construction materials, filling materials, and back filling materials. In addition, this study was conducted to analyze strength properties and fiber reinforcing effect with fiber mixed soil by direct-shear test. In case of fibrillated fiber mixed soil, the more quantity of fiber was in both cohesive soil and sandy soil, the larger shear stress was in respective step of normal load. The respective mixed soil at 0.5% and 0.1% mixing ratio of monofilament fiber mixed soil showed maximum shear stress. According to unconfined compression or direct-shear test, making specimen of the monofilament fiber mixed soil, it is required to be careful and stable mixing method, while it is expected that monofilament fiber mixed soil doesn't increase strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.210-219
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• 1997

This research which lays emphasis on ready mixed concrete standard 25-210~240kgf/$\textrm{cm}^2$ shows the influence caused by the ratio of ingredients of superplasticized concrete, and the flowing and strength development of mortar and concrete according to the ratio of ingredients. This research shows that flowability, compactability, and segregation resistivity are the best condition under the following ratio of ingredients: fly ash 30%, unit binders 490~510kg/$\textrm{m}^3$, unit weight of water 184~194kg/$\textrm{m}^3$, fine aggregate ratio 49~51%, and superplasticizer 1.1~1.5%. Following this ratio of ingredients, the reinforced concrete structures to need design strength 25-210~240kgf/$\textrm{cm}^2$ can apply to complicated constructions.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.561-568
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• 2002

PFA(Paper Fly Ash) are reclaimed mainly or used in cement industry field as mixture agent in terms of materials recycling. Recently, research for recycling PFA as embankment materials or soil stabilization agent are undergoing in geotechnical engineering field. In this study, physical characteristics of PFA stabilization agent-soil admixtures are examined in change of water content, void ratio, consistency, grain distribution, specific gravity and density. Futhermore, the physical characteristics are compared with unconfined strength as engineering characteristics. Test results showed that unconfined strength and density are increased with increasing of PFA stabilization agent mixed ratio. On the other hand, specific gravity, void ratio and water content are decreased with increasing of PFA stabilization agent mixed ratio. It would be concluded that natural high water content ratio weak soil could be highly improved engineering and physical characteristics with PFA stabilization agent

• 전기화학회지
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• 제6권2호
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• pp.134-140
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• 2003

기능성 도판트인 dodecylbenzensulfonic acid(DBSA)와 혼합도판트{(DBSA와 $LiClO_4$, NSA(2-naphthalenesulfonic acid), DEHSA[di(2-ethylhexyl)sulfosuccinic acid]}를 사용하여 전기화학적방법에 의한 연신성 폴리피롤(Ppy-DBSA, Ppy-mixed dopants)필름을 제조하였다. 전기화학적 방법에 의해 제조된 폴리피를 괼름은 zone drawing방법을 사용하여 1.0-2.5배 연신시킬 수 있었으며, 연신된 폴리피롤 필름의 전기전도도를 측정하였다. 연신율이 증가함에 따라 필름의 전기전도도가 증가함을 볼 수 있었다. 이 현상은 연신율에 따른 결정성 증가로 설명 할 수 있었다. 1.0-2.5배 연신된 폴리피를 필름(Ppy-DBSA, Ppy-mixed dopants)을 온도변화에 따른 전하 이동 경로는 모두 power raw에 적합함을 볼 수 있었다.

• 한국수소및신에너지학회논문집
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• 제18권1호
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• pp.75-84
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• 2007

The effects of hydrogen enrichment to methane on NOx formation have been investigated with swirl stabilized pre-mixed hydrogen enriched methane flame in a laboratory-scale pre-mixed combustor(nominally of 5,000 kcal/hr). The hydrogen enriched methane fuel and air were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame stability was examined for different amount of hydrogen addition to the methane fuel, different combustion air flow rates and swirl strengths by comparing equivalence ratio at the lean flame limit. The hydrogen addition effects and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using gas analyzers, and OH chemiluminescence techniques to provide information about species concentration of emission gases and flowfield. The results of NOx and CO emissions were compared with a diffusion flame type combustor. The results show that the lean stability limit depends on the amount of hydrogen addition and the swirl intensity. The lean stability limit is extended by hydrogen addition, and is reduced for higher swirl intensity at lower equivalence ratio. The addition of hydrogen increases the NOx emission, however, this effect can be reduced by increasing either the excess air or swirl intensity. The NOx emission of hydrogen enriched methane premixed flame was lower than the corresponding diffusion flame under the fuel lean condition.

• 한국지반신소재학회논문집
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• 제2권1호
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• pp.27-37
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• 2003

섬유혼합토의 전단강도 및 마찰 특성에 영향을 미치는 요인으로는 혼합되는 흙의 입도분포와 흙입자의 형상 등과 같은 흙의 공학적 특성과 섬유의 형상, 길이, 직경, 인장강도, 탄성계수, 마찰계수, 섬유 혼합률 등과 같은 섬유의 물리적 역학적 특성 그리고 구속응력, 다짐상태 등의 외적 인자 등을 들 수 있다. 본 연구에서는 흙종류, 섬유종류, 섬유혼합률 그리고 다짐도에 따른 섬유혼합토의 마찰특성을 평가하기 위하여 일련의 전단마찰시험 및 인발시험을 수행하였다. 본 연구에서는 공학적으로 그 특성이 다소 불량한 두 가지 종류의 흙시료(통일분류법상 SM 및 ML)에 세 가지 종류의 폴리프로필렌 섬유(망사 38mm, 망사 60mm 및 단사 60mm)를 0.2% 및 0.3%의 혼합률로 혼합한 섬유혼합토를 다짐도 85% 및 95%로 조성하여 실험을 수행하였고, 보강재로는 지오그리드를 사용하였다.

• Mass Spectrometry Letters
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• 제2권4호
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• pp.80-83
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• 2011

Isotope ratio analysis of nuclear materials in individual particles is of great importance for nuclear safeguards. Although secondary ion mass spectrometry (SIMS) and thermal ionization mass spectrometry (TIMS) are utilized for the analysis of individual uranium particles, few studies were conducted for the analysis of individual uranium-plutonium mixed oxide particles. In this study, we applied SIMS and inductively coupled plasma mass spectrometry (ICP-MS) to the isotope ratio analysis of individual U-Pu mixed oxide particles. In the analysis of individual U-Pu particles prepared from mixed solution of uranium and plutonium standard reference materials, accurate $^{235}U/^{238}U$, $^{240}Pu/^{239}Pu$ and $^{242}Pu/^{239}Pu$ isotope ratios were obtained with both methods. However, accurate analysis of $^{241}Pu/^{239}Pu$ isotope ratio was impossible, due to the interference of the $^{241}Am$ peak to the $^{241}Pu$ peak. In addition, it was indicated that the interference of the $^{238}UH$ peak to the $^{239}Pu$ peak has a possibility to prevent accurate analysis of plutonium isotope ratios. These problems would be avoided by a combination of ICP-MS and chemical separation of uranium, plutonium and americium in individual U-Pu particles.

• Korean Chemical Engineering Research
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• 제51권6호
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• pp.677-684
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• 2013

혼합냉매를 사용하여 천연가스를 액화하는 혼합냉매공정(Mixed refrigerant cycle, MRC)은 공정이 간단하고 장치비가 적게 들며 운전 또한 용이하여 널리 채택되고 있는 공정이다. MRC에서 중요한 기술 중 하나는 혼합냉매를 선택하고 최적의 혼합비를 결정하는 것이다. 본 연구에서는 일반적인 MRC에서 혼합냉매와 혼합냉매의 혼합비가 공정의 성능에 미치는 효과를 살펴보았다. 이를 위해 통계적 기법 중 실험계획법의 하나인 혼합물 설계와 반응 표면법을 이용하여 전체 공정의 에너지 소비가 최소가 되게 하는 최적의 냉매를 선택하고 그 혼합비를 결정하였다. 여러 냉매와 혼합비에 따른 MRC 공정의 모사는 Aspen HYSYS를 사용하였으며 혼합물설계와 반응 표면법은 Minitab을 사용하였다. 연구결과 냉매로는 methane ($C_1$), ethane ($C_2$), propane ($C_3$)과 nitrogen ($N_2$)가 선택되었으며 에너지 소비를 최소화하는 혼합비(몰 비) 또한 구할 수 있었다.

• 한국의류산업학회지
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• 제13권5호
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• pp.790-796
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• 2011

This study was designed to investigate the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil under various solutions. The detergency of the particulate soil was determined by adhesion of particle to fabric and its removal from fabric separately. The PET fabric and ${\alpha}-Fe_2O_3$were used as materials of textile and model of particulate soil, respectively. The detergency was investigated as a function of surfactants concentration, ionic strength, kinds of electrolyte and mole numbers of oxyethylene ether of nonionic surfactant in different ratio of anionic/nonionic surfactant mixture. Although some deviations exist, the adhesion of particle to fabric generally increased with decreasing its removal from fabric. The detergency of particulate soil on PET fabric was relatively higher in anionic/nonionic surfactant mixed solution than in each single surfactant solution, but the influence of ratio of anionic/nonionic surfactant mixture on detergency of particulate soil was low. Generally the detergency of particulate soil on fabric was at its maximum at 0.1% surfactant concentration, $1{\times}10^{-3}$ ionic strength, $Na_5P_3O_{10}$ electrolytes and 10 mole numbers of oxyethylene ether of nonionic surfactant, regardless of ratio of anionic/nonionic surfactant mixture.

• 한국지반공학회논문집
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• 제19권2호
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• pp.189-197
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• 2003

본 논문은 공진주시험과 삼축압축시험을 이용하여 소변형률(0.0001%~l%) 범위에서 섬유혼합토의 변형 특성을 규명하였으며, 최대전단탄성계수를 잣대로 보강효과를 평가하였다. 또한 단섬유의 직경에 대한 길이의 비(형상비), 흙의 중량에 대한 섬유 중량의 섬유혼합비, 단섬유의 종류에 따른 보강효과를 비교 검토하였다. 시료는 주문진 표준사에 폴리프로필렌 재질의 단섬유를 무작위로 배합하여 사용하였다. 섬유혼합토의 최대전단탄성계수는 비혼합토에 비해 최대 30%까지 증가하였고, 비선형 영역에서의 전단탄성계수 감소량도 억제되었다. 형상비가 증가할수록 최대전단 탄성계수는 증가하고, 단사에 비해 망사의 보강 효과가 큰 것으로 나타났다. 섬유혼합비는 0.3 % 부근에서 보강효과가 가장 커, 최적인 것으로 확인되었다.