• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.955-963
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• 2008

There are lots of tunnel intervals in the KTX II stage construction line for the linearity of railway line passing mountain region. In order to use the rocks from tunnel excavations, railway subgrades are constructed with crushed rock-soil mixtures. In this study, plain strain test using large scale box was conducted in order to analyze the characteristics of deformation behavior of railway subgrades composed of crushed rock-soil mixtures. The effects of variation of degree of saturation, stress level of applied loadings, and number of loading cycles on the resilient and permanent deformation behavior were analyzed. The results show that degree of saturation have a great effect on the deformation behavior of crushed rock-soil mixtures. The axial strain ranges between $0.1{\sim}0.8%$ with variation of degree of saturation, in assumption that deviatoric stress applied on the subgrade by high-speed train load is 55kPa.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.1190-1200
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• 2010

A method was developed to determine resilient modulus for crushed rock-soil mixtures whose usage has been increased recently without engineering specifications. The method is based on the subtle different modulus called nonlinear dynamic modulus and was lately implemented in residual soils and engineered crushed-stones. Hereby. the same method was expanded to crushed rock-soil mixtures containing as large grain diameter as 300mm. The method utilize field direct-arival tests for the determination of maximum Young's modulus, and a large scale free-free resonant column test, which is recently developed to is capable to test as large grain diameter as 25mm, for modulus reduction curves. The prediction model of resilient modulus was evaluated for crushed rock-soil mixtures of a highway construction site at Gimcheon, Korea.

• 한국연소학회지
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• 제22권1호
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• pp.23-31
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• 2017

Large-scale fuel tanks emit massive amount of hardly-combustible VOC mixtures which are light hydrocarbon species in dilution with nitrogen and carbon dioxide. We have developed a lab-scale burner to combust those VOC mixtures by use of a turbulent partially-premixed flame as a pilot flame. For a higher HC treatment ratio, the mixture gases were reformed by a rotating arc plasma device. The results showed that the nitrogen mole fraction and the injecting speed of the VOC mixture influence on the performance of the burner. It was also found that the size of the pilot flame and the power supplied to the plasma device determine the overall HC treatment ratio and the concentrations of CO and NOx in the exhaust gas.

• 한국도로학회논문집
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• 제13권2호
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• pp.41-48
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• 2011

아스팔트 혼합물을 중온에서 생산하여 다짐할 수 있는 중온 아스팔트 기술이 개발되었다. 중온 아스팔트 기술은 유해가스를 줄일 수 있어 친환경적 아스팔트 포장 기술로 인정받고 있으며 전 세계적으로 그 사용량이 점점 증가하고 있다. 최근, 국내에서도 순수 국산화 기술로 중온 아스팔트 혼합물용 첨가제를 개발하여 이에 대한 품질평가와 중온 아스팔트 혼합물에 대한 성능평가를 수행하고 있다. 2008년도부터 다수의 신설 국도 구간에 자체 개발한 중온 아스팔트 첨가제를 사용하여 생산한 중온 아스팔트 혼합물을 이용하여 시험포장을 성공적으로 완료하였다. 2010년 대전지방국도관리청 산하 신설 국도포장의 중간층에 두 종류에 중온화 첨가제(일반 중온화 첨가제(WMA), 폴리머 개질 중온화 첨가제(WMA-P))를 사용한 두 종류에 중온 아스팔트 혼합물과 한 종류에 가열 아스팔트 혼합물을 각각 생산하여 시험포장을 완료하였으며 시함포장에 사용한 혼합물을 사용하여 본 연구를 수행하였다. 현장 아스팔트 플랜트에서 생산된 두 종류의 중온 아스팔트 혼합물(WMA, WMA-P)과 일반 가열 아스팔트 혼합물(HMA)을 각각 채취하였으며 실내에서 실제 도로에서 발생하는 차량하중과 환경을 모사할 수 있는 소형 포장 가속시험기(MMLS3)를 사용하여 아스팔트 혼합물의 소성변형 저항성과 수분민감도를 비교 평가하였다. 소형 포장 가속 시험결과 현장 아스팔트 플랜트에서 생산한 중온 아스팔트 혼합물은 가열 아스팔트 혼합물보다 우수한 소성변형저항성과 수분민감도를 보여 주었다. 순수 국산화 기술로 중온 아스팔트 혼합물용 첨가제는 가열 아스팔트 혼합물 보다 낮은 온도에서 중온 아스팔트 혼합물을 생산하고 다짐하는데 효과적인 것으로 평가되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.551-556
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• 2002

High-performance concrete is defined as concrete that meets special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practices. Ever since the term high-performance concrete was introduced into the industry, it had widely used in large-scale concrete construction that demands high-strength, high-flowability, and high-durability. To obtain such performances that cannot be obtained from conventional concrete and by the current method, a large number of trial mixes are required to select the desired combination of materials that meets special performance. In this paper, therefore, using genetic algorithm which is a global optimization technique modeled on biological evolutionary process-natural selection and natural genetics-and can be used to find a near optimal solution to a problem that may have many solutions, the new design method for high-performance concrete mixtures is suggested to reduce the number of trial mixtures with desired properties in the field test. Experimental and analytic investigations were carried out to develop the design method for high-performance concrete mixtures and to verify the proposed mix design.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.77-93
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• 2019

Although much research has been carried out using recycled aggregates sourced from normal strength concrete, most of the buildings to be demolished are constructed with low strength concrete. Therefore, the properties of the concrete incorporating recycled aggregates, sourced from the waste of structural elements cast with low strength concrete, were investigated in this study. Four different concrete mixtures were designed incorporating natural and recycled aggregates with and without fly ash. The results of the mechanical and durability tests of the concrete mixtures are presented. Additionally, full-scale one-way reinforced concrete slabs were cast, using these concrete mixtures, and subjected to bending test. The feasibility of using conventional reinforced concrete theory for the slabs made with structural concrete incorporating recycled aggregates was investigated.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1999년도 PROCEEDINGS OF 99 INTERNATIONAL CONFERENCE OF THE KACG AND 6TH KOREA·JAPAN EMG SYMPOSIUM (ELECTRONIC MATERIALS GROWTH SYMPOSIUM), HANYANG UNIVERSITY, SEOUL, 06월 09일 JUNE 1999
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• pp.69-80
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• 1999

Computer simulations have played a central role in the development of out understanding of the atomic scale processes involved in crystal growth. The assumptions underlying computer modeling will be discussed and out recent work on modeling of the kinetic formation of thermodynamically unstable phases in alloys or mixtures will be reviewed. Our Monte Carlo computer simulations have reproduced the experimental results on the rapid recrystallization of laser-melted doped silicon. An analytical model for this phenomenon has been developed, and its applicability to other materials will be discussed.

• 한국결정성장학회지
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• 제9권4호
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• pp.365-370
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• 1999

Computer simulations have played a central role in the development of our understanding of the atomic scale processes involved in crystal growth. The assumptions underlying computer modeling will be discussed and our recent work on modeling of the kinetic formation of thermodynamically unstable phases in alloys or mixtures will be reviewed. Our Monte Carlo computer simulations have reproduced the experimental results on the rapid recrystallization of laser-melted doped silicon. An analytical model for this phenomenon has been developed, and its applicability to other materials will be discussed.

• 한국도로학회논문집
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• 제18권2호
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• pp.61-71
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• 2016

PURPOSES: The objective of this study was to determine the optimum ratio of mix design, for a reclaimed asphalt pavement (RAP) content of 100%, for spray injection application. METHODS: A literature review revealed that spray injection is an efficient and cost-effective application for fixing small defective regions of an asphalt pavement. Rapid-setting polymer-modified asphalt mixtures prepared from two types of rapid-setting polymer asphalt emulsion were subjected to Marshall stability and wet track abrasion tests, in order to identify the optimum mix designs. RESULTS and CONCLUSIONS : Different mix designs of type A and type B emulsions were prepared using RAP and virgin aggregates, in order to compare the performance and determine the optimum mix design. The performance of mixtures prepared with RAP was superior to that of mixtures containing virgin aggregates. Moreover, for optimum ratio of the design, the binder content prepared from RAP was set to 1~2% lower than that consisting of virgin aggregates. Compared to their Type A counterparts, type B mixtures consisting of a reactive emulsion performed better in the Marshall stability and wet track abrasion tests. The initial results confirmed the advantages associated with using RAP for spray injection applications. Further studies will be performed to verify the difference in the optimum mix design and performance obtained in the lab-scale test and tests conducted at the job site by using the spray injection machine.

• 한국지반공학회논문집
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• 제27권11호
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• pp.39-45
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• 2011

본 연구는 글라스 비드와 고무 혼합재의 부피비와 상대적인 크기 비에 따른 열적 거동에 관해 다루고 있다. 혼합 물질의 열전도도를 측정하기 위하여 비정상면열원법이 사용되었다. 개별요소법과 열 네트워크 모델을 결합하여 입상체 모사 시료에서 입자 단위의 열전달 매커니즘을 분석하였다. 실험 및 해석의 결과는 다음과 같다. 유효 열전도도는 고무의 부피비가 증가할수록 감소한다. 두 물질의 상대적인 크기는 열 전파경로의 대부분을 결정하는 입자간 접촉상태의 공간적 구성을 지배한다. 같은 부피비를 갖는 혼합물질 중에서, 열이 잘 흐르지 않는 물질(여기에서는 고무)의 입자 크기가 큰 경우 열전달이 더 원활하게 이루어진다. 이상의 실험결과와 입자 단위의 관찰은 물질의 열적 거동이 부피비 뿐 아니라 구성 성분의 공간적인 구성에도 영향을 받음을 보여준다.