PURPOSES: This research is to evaluate the mechanical performance of different types of Hot Mix Asphalt (HMA) pavement cells prepared for MN/Road field testing section through an extensive experimental analysis of air voids and simple statistical evaluation tools (i.e. hypothesis test). METHODS: An extensive experimental work was performed to measure air voids in 82 asphalt mixture cores (238 samples in total) obtained from nine different types of road cell located in MN/Road testing field. In order to numerically and quantitatively address the differences in air voids among the different test Cells built in MN/Road, a simple statistical test method (i.e. t-test) with 5% significance was used. RESULTS: Similar trends in air voids content were found among the mixtures including conventional HMA, Reclaimed Asphalt Pavement (RAP) and Warm Mix Asphalt (WMA) combined with taconite aggregate this provides support to the use of RAP and WMA technology in the constructions of asphalt pavement. However, in case of acid modified HMA mixtures, significant differences in air void content were observed between on the wheel path and between wheel path location, which implies negative performances in rutting and thermal cracking resistances. Conclusions : It can be concluded that use of RAP and WMA technology in the construction of conventional asphalt pavement and the use of PPA (Poly Phosphoric Acid) in combinations with SBS (Styrene Butadiene Styrene) in asphalt binder production provide satisfactory performance and, therefore, are highly recommended

PURPOSES : The objective of this study is to analyze the performance of anti-stripping agent depending on its type and content to reduce pothole, an increasing pavement distress due to abnormal climate intensity. METHODS : In the past years, U.S and many countries in Europe use hydrated lime and liquid anti-stripping agent in asphalt mixtures. Hydrated lime or liquid anti-stripping agent is substituted for filler and binder, respectively, to improve the anti-stripping property of asphalt mixtures. To investigate this, indirect tensile strength test was performed and TSR values were compared for different content of hydrated lime and types of liquid anti-stripping agent in asphalt mixture. RESULTS : Test results indicate that hydrated lime remarkably increased the asphalt mixture performance on anti-stripping denoted by the increased in TSR values from 55% to 100%. Liquid anti-stripping agent also increased the value of TSR but not significant. In addition, depending on the types of aggregate, TSR values and effect of liquid anti-stripping were different. CONCLUSIONS : Using anti-stripping agents improve the anti-stripping property of asphalt mixture especially hydrated lime; however, more experiments should be conducted to improve the reliability about the effect of liquid anti-stripping agent.

하천부지에서 이탈리안 라이그라스(IRG)와 월년생 두과작물을 혼파하여 사초 생산성과 토양 특성을 조사하였다. 안산천 하천부지에서는 이탈리안 라이그라스와 헤어리베치의 혼파조합이 다른 조합보다 생초, 건물 및 수량이 가장 많았다. 이탈리안 혼파조합의 수확 시 건물률도 헤어리베치 조합이 가장 높았다. 혼파조합의 사료가치 비교에서 헤어리베치 조합이 조단백질 함량은 높았으나 TDN 및 비섬유성탄수화물(NFC) 함량은 다른 처리구에 비하여 낮았다. 따라서 질소 고정능력이 우수한 헤어리베치 조합이 다른 조합보다 토양의 전질소(TN) 함량이 높았다. 반면 토양의 유기물 함량은 유채 조합이 가장 높았으며, 토양의 유효인산 함량은 크림손 클로버 조합이 높았다. 토양의 CEC 함량은 이탈리안 라이그라스와 헤어리베치 조합은 우수하였다. 이상의 결과를 종합해 볼 때 비료를 시용하지 못하는 하천변에서 월동 사료작물을 재배할 때 이탈리안 라이그라스와 헤어리베치의 혼파조합이 다른 혼파조합보다 사초생산성이 높아 토양의 질소와 인 제거에 의한 하천 수질 개선에 효과가 좋은 것으로 판단되었다.

이산화탄소의 효과적인 분리 및 포집을 위해서 등방성 다공성 구조의 폴리프로필렌(pp) 격자의 내부에 제올라이트 입자들이 표면 덮임 없이 균일하게 분포되어 있는 흡착투과중공사막(APM: adsorptive permeation hollow fiber membrane)을 개발하였다. 본 연구에서는 이산화탄소/질소 혼합물을 모사 기체혼합물로 사용하였는데, 공급되는 기체혼합물 모두가 APM을 투과하면서 이산화탄소는 APM 내 분포되어 있는 흡착제에 흡착되고 질소는 투과하여 배출된다. APM이 장착된 모듈을 제조하여 이에 대한 흡착투과실험을 수행하여 흡착투과 성능을 분석하였고 또한 포화 흡착된 APM을 진공압에서 탈착재생하여 그 결과를 재생효율과 에너지소모 관점에서 고찰하였다.

The milling and particulate characteristics of Al alloy-Al2O3 powder mixtures for a reaction-bonded Al2O3 (RBAO) process were studied. A commercially available prealloyed Al powder with Zn, Mg, Cu and Cr alloying elements (7475 series) was mixed with a calcined sinter-active Al2O3 powder and then milled in centrifugal milling equipment for ~48 hrs. The Al alloy-Al2O3 powder mixtures after milling were characterized and evaluated in various ways to reveal their particulate characteristics during milling. The milling efficiency of the Al alloy increased with a longer milling time. Comminution of the Al alloy particles started with its elongation, showing a high aspect ratio. With a longer milling time, the elongated Al alloy particle changed in terms of its shape and size, becoming equiaxially fine particles. Regardless of the milling efficiency of the Al alloy particles, all of the Al alloy particles repeatedly experienced strong plastic deformation during milling, giving rise to higher density of surface defects, such as microcracks, and leading to higher residual microstress within the Al alloy particles. The chemical reactions, oxidation behavior and hydration behavior of the Al alloy particles and the hydrolysis characteristics of their reaction with the environment were also observed during the milling process and during the subsequent powder handling steps.

CSA, a cement mineral compound that is mainly composed of 3CaO·3Al2O3·CaSO4, generates ettringite as a hydration product after a reaction with glass (lime), gypsum and water to speed up the hardening process and enhance the strength and degree of expansion. When used as a cement admixture, there is increased production of ettringite, which can improve the initial strength in the first three days and ameliorate the reduction in the initial strength caused by the use of fly ash in particular. In this study, a hydrate analysis was performed using XRD and SEM after substitution with fly ash (30%) and CSA (8%) with the goal of observing the effect of CSA on the initial strength of a cement mixture containing fly ash. The results of the analysis showed that an addition of CSA promoted the production of ettringite and improved the initial strength, resulting in the generation of hydrates, which can effectively enhance the long-term strength of these materials.

Poly (vinylidene fluoride) (PVDF)ㆍpoly (acrylonitrile) (PAN) 중공사막에 친수성 고분자인 poly (vinyl alcohol) (PVA)과 가교제인 poly (acrylic acid) (PAA)을 코팅하여 복합막을 제조하였다. 제조된 막의 투과특성평가를 위해 90 wt% 물- 에탄올 혼합액에 대한 투과증발실험을 수행하였으며, 반응온도, PAA용액의 농도, 공급액의 온도변화에 따른 투과도 및 선택도를 측정하였다. 일반적으로 반응온도, PAA용액의 농도가 증가할수록 투과도는 낮아지고 선택도는 증가하는 경향을 보였으며, 공급액의 온도가 증가할수록 투과도는 증가하고 선택도는 낮아지는 경향을 보였다. 대표적으로 PVDF중공사 막은 투과도는 PAA 3 wt%, 반응온도 60°C, 공급액 온도 70°C에서 502 g/m 2 hr, 선택도는 PAA 11 wt%, 반응온도 100°C, 공급액 온도 50°C일 때, 218의 결과를 얻을 수 있었다.

PURPOSES : The purpose of this study is to evaluate the durability of ternary blended concrete mixtures adding ultra fine admixture. METHODS : From the literature review, crack was considered as the main distress failure criterion on concrete bridge deck pavement. To reduce the initial crack development due to drying shrinkage, CSA expansion agent and shrink reduction agent were used to ternary blended concrete mixtures as a admixture. Laboratory tests including chloride ion penetration test, surface scaling test, rapid freeze & thaw resistance test, non restrained drying shrinkage and restrained drying shrinkage test were conducted to verify the durability of ternary blended concrete mixtures. RESULTS : Based on the test results, proposed mixtures were verified as high qualified durable materials. Expecially initial drying shrinkage crack was not occurred in ternary blended concrete mixtures with CSA expansion agent. CONCLUSIONS : It is concluded that the durability of proposed ternary blend concrete mixture was acceptable to apply for the concrete bridge deck pavement.

Poly(vinyl alcohol) (PVA)에 대하여 가교제로써 glutaraldehyde (GA), maleic anhydride (MA)를 이용하여 제조한 코팅용액을 알칼리로 가수분해 시킨 poly acrylonitrile (PAN) 중공사 막표면에 코팅하여 막을 제조하였다. 제조된 막의 투과 특성평가를 위해서 물/에탄올 혼합액에 대한 투과증발 실험을 수행하였다. 60°C의 90 wt%의 물/에탄올 혼합액에 대하여 반응온도 및 가교제의 농도변화에 따른 투과도 및 선택도를 측정하였다. 일반적으로 반응온도, 가교제 농도가 증가할 경우 투과 도는 낮아지고, 선택도는 증가하는 경향을 보여주었다. 가교제로 GA의 대표적 결과는 반응온도 120°C, GA 11 wt%로 투과 도는 165 g/m 2 hr 선택도는 81이고, MA는 반응온도 120°C, MA 11 wt%로 투과도는 174 g/m 2 hr 선택도는 73의 결과를 얻을 수 있었다.

PURPOSES : The main purposes of this study are to examine the influences of polyethylene wax-based WMA additive on the optimum asphalt content of warm-recycled asphalt mixture based on the Marshall mix design and to evaluate performance of warm-recycled asphalt mixture containing 30% RAP with polyethylene wax-based WMA additive. METHODS: Physical and rheological properties of the residual asphalt were evaluated in terms of penetration, softening point, ductility and performance grade (PG) in order to examine the effects of polyethylene wax-based WMA additive on the residual asphalt. Also, To evaluate performance characteristics of the warm-recycled asphalt mixtures using polyethylene wax-based WMA additive along with a control hot-recycled asphalt mixture, indirect tensile strength test, modified Lottman test, dynamic immersion test, wheel tracking test and dynamic modulus test were conduced in the laboratory. RESULTS : Based on the limited laboratory test results, polyethylene wax-based WMA additive is effective to decrease mixing and compacting temperatures without compromising the volumetric characteristics of warm-recycled asphalt mixtures compared to hot-recycled asphalt mixture. Also, it doesn't affect the optimum asphalt content on recycled-asphalt mixture. All performance test results show that the performance of warm-recycled asphalt mixture using polyethylene wax-based WMA additive is similar to that of a control hot-recycled asphalt mixture. CONCLUSIONS: Overall, the performance of warm-recycled asphalt mixture using polyethylene wax-based WMA additive is comparable to hot-recycled asphalt mixture.

PDMS 단일 막을 이용한 투과증발공정을 통해 이소프로필알코올(Isopropyl alcohol, IPA)―물계에 대한 분리특성 을 알아보았다. RTV-655 주재와 가교제의 비율을 9:1과 10:1로 달리하고 반응온도를 40, 60, 80°C로 변화하여 경화시켰다. 이렇게 제조된 막을 이용하여 특성평가를 위해 물/IPA 혼합액에 대한 투과증발 실험을 수행하였다. 공급액의 조성은 85 wt% IPA 수용액을 사용하였으며, 온도는 25, 35, 45, 55°C로 변화시켰다. 공급액의 변화와 반응온도의 조건변화에 따른 투과도 및 IPA 농축농도를 측정하였는데, 투과도는 9:1 비율, 공급액 온도 55°C일 때 148 ⋅, 선택도는 10:1 비율, 공급액 온도 55°C일 때 17%로 가장 높은 값을 얻을 수 있었다.

PURPOSES: This study is to evaluate the dynamic modulus changes of permeable asphalt mixtures by using non-destructive impact testing method and to compare the dynamic moduli of permeable asphalt mixtures through repeated freezing and thawing conditions. METHODS: For the study, non-destructive impact testing method is used in order to obtain dynamic modulus of asphalt specimen and to confirm the change of dynamic modulus before and after freezing and thawing conditions. RESULTS : This study has shown that the dynamic moduli of asphalt concrete specimens consisting of 10%, 15% and 20% porosity are reduced by 11.851%, 1.9564%, 24.593% after freezing and thawing cycles. CONCLUSIONS : Non-destructive impact testing method is very useful and has repeatability. Specimen with 15% porosity has high durability than others.

PURPOSES : This study is to evaluate moisture susceptibility of asphalt mixtures by using non-destructive impact wave and to determine durability so as to decrease the gap between before and after freezing in the future. METHODS : Using non-destructive impact wave, this study is to determine the dynamic modulus of asphalt specimen. Furthermore, the results obtained from two experiment accelerometers are used for the dynamic modulus determination. The dynamic moduli of specimens are compared with those of the freezing-thawing specimens. RESULTS : Test results showed that the dynamic modulus before freezing and thawing environment loads at each temperature dropped about 3.7% after the environmental loads. Furthermore, correlation analysis indicates that transition of dynamic modulus at each point is about 89.59%. CONCLUSIONS: Evaluation of asphalt mixtures using non-destructive impact wave has excellent repeatability and simple equipment for the test. Consequently, the method in the study will be useful for evaluating the characteristics of a various asphalt mixtures.

지지체인 Polyacrylonitrile (PAN) 중공사에 Poly (vinyl alcohol) (PVA)과 가교제인 Glutaraldehyde (GA)를 코팅하 여 막을 제조하였으며, 특성평가를 위해 물/Isopropyl alcohol (IPA) 혼합액에 대한 투과증발 실험을 수행하였다. 코팅용액의 조성변화와 반응온도의 조건변화에 따른 투과도 및 선택도를 측정하였고, 공급액의 조성은 85 wt% IPA 수용액을 사용하였으며, 온도는 30, 50, 70, 90℃로 변화시켰다. 투과도는 PVA 3.5 wt%, 공급액 온도가 90℃일 때 1,870 g/m 2 ⋅hr, 선택도는 PVA 7 wt% 공급액 온도가 30℃일 때 804로 가장 높은 값을 얻을 수 있었다.

Ultra-fine zirconium carbide (ZrC) powder with nano-sized primary particles was synthesized by the carbothermal reduction method by using nano-sized and nano-sized graphite powders mixture. The synthesized ZrC powder was well dispersed after simple milling process. After heat-treatment at for 2 h under vacuum, ultra-fine ZrC powder agglomerates (average size, ) were facilely obtained with rounded particle shape and particle size of ~200 nm. Ultra-fine ZrC powder with an average particle size of 316 nm was obtained after ball milling process in a planetary mill for 30 minutes from the agglomerated ZrC powder.

본 연구는 항산화활성을 나타내는 식물추출물을 이용하여 가축용 사료첨가제를 개발하기 위한 목 적으로 수행되었다. 총 10가지의 식물들(익모초, 뽕나무 잎, 두충, 민들레, 엄나무, 삼백초, 꾸지뽕나 무, 감나무 잎, 헛개나무 및 가시오갈피)을 열수추출 방법을 이용하여 추출물을 준비하였고, 식물추 출물들의 총 폴리페놀, 총 플라보노이드 함량을 조사하였으며, 항산화활성을 측정하였다. 항산화활성 의 측정 후, 모든 추출물들이 혼합된 상태에서 항산화활성 향상에 효과를 나타내는 추출물들을 부분 요인실험설계법의 일종인 Plackett-Burman 실험설계법을 이용하여 선별하였으며 우수한 항산화활 성을 보이는 식물추출물들을 통계적인 방법인 혼합물실험설계법을 이용하여 조합하였고 이 조합들에 서 얻어진 반응들은 root mean square prediction error측정법을 적용하여 계산하였다. 유의적으로 긍정적효과를 나타낸 식물추출물들로는 뽕나무 잎, 감나무 잎 및 가시오갈피로 나타났다. 이 세 가지 식물추출물들의 최적 혼합비율을 도출하기 위하여 통계적인 방법을 적용한 결과로 뽕나무 잎 추출물, 감나무 잎 추출물 및 가시오갈피 추출물의 혼합비율이 0.44 : 0.28 : 0.28에서 가장 우수한 항산화활성 이 나타났다. 본 연구의 결과에 의하면 통계적인 방법을 이용하여 항산화활성이 우수한 식물추출물의 조 합을 용이하게 도출할 수 있고 이를 기초로 추가적인 연구에 응용할 수 있을 것으로 사료된다.

The effects of clay, aluminum hydroxide, and carbon powder on the sintering of a Si/SiC mixture from photovoltaic silicon-wafer production were investigated. Sintering temperature was fixed at 1,350˚C and the sintered bodies were characterized by SEM and XRD to analyze the microstructure and to measure the apparent porosity, absorptivity, and apparent density. The XRD peak intensity of SiC in the sintered body was increased by adding 5% carbon to the Si/SiC mixture. From this result, it is confirmed that Si in the Si/SiC mixture had reacted with the added carbon. Addition of aluminum hydroxide decreased the cristobalite phase and increased the stable mullite phase. The measurement of the physical properties indicates that adding carbon to the Si/SiC mixture enables us to obtain a dense sintered body that has high apparent density and low absorptivity. The sintered body produced from the Si/SiC mixture with aluminum hydroxide and carbon powder as sintering additives can be applied to diesel particulate filters or to heat storage materials, etc., since it possesses high thermal conductivity, and anticorrosion and antioxidation properties.

노면표시에 도포된 굴절률 1.5 유리알은 야간 우천 시 효과적인 재귀반사를 수행하지 못하여 교통안전에 심각한 문제를 초래하고 있다. 이를 극복하기 위해 습윤상태에서 효과적 재귀반사를 수행하는 굴절률 2.4인 우천형 bead와 건조 시 최적의 재귀반사를 수행해 내는 굴절률 1.9 bead를 혼합한다. 그러나 고성능의 굴절률 1.9와 2.4 bead는 기존 1.5 유리알에 비해 상당한 고가이므로 전량 사용하기에는 상당한 비용이 소요된다. 따라서 현장 설치 시에는 서로 혼합하여 사용하는 것이 바람직하며, 최적 성능과 소요 비용을 고려한 적정 배합비율을 찾아내는 것이 중요하다. 본 연구에서는 다양한 비율로 혼합된 bead를 국내 고속도로의 길가장자리선에 설치하였을 때 발생되는 각각의 비용 및 편익에 따른 경제성 분석을 수행하였다. 분석 수행결과, 다양한 강수량 변화에도 높은 시인성을 유지하는 대안은 굴절률 2.4가 100% 구성된 차선으로 나타났으며, 경제성이 가장 높게 확보되는 대안은 굴절률 1.5가 80%, 2.4가 20%로 구성된 차선으로 B/C는 약 1.92 수준으로 도출되어 국내 고속도로 길가장자리선의 적용 시 가장 효과적인 대안인 것으로 확인되었다. 아울러 연구의 한계와 몇몇 장래 연구과제가 토의되었다.