• 한국지반신소재학회논문집
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• 제14권1호
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• pp.33-41
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• 2015

본 연구에서는 관중혼합처리공법 개발을 위해 혼합토의 공학적 특성 평가에 관한 실내실험(유동성, 단위중량, 일축압축강도 및 블리딩 시험)을 수행하였다. 실험 결과 흐름 및 블리딩 특성은 함수비에 비례하여 증가하는 것으로 나타났다. 단위중량과 일축압축강도는 함수비 증가에 따라 감소하는 것으로 나타났다. 각 주행 장비별 접지압과 혼합토의 지지력을 비교한 결과 벨트 컨베이어, 백호우, 도저 등의 장비가 즉시 진입 가능한 것으로 검토되었다. 결과적으로 고화재를 사용한 관중혼합처리공법에서 적용 가능한 함수비 영역은 80~200%로 평가되었다. 또한, 본 연구 결과로부터 설계 차트를 개발하여 제시하였다.

• Steel and Composite Structures
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• 제27권1호
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• pp.27-33
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• 2018

In this study, a mixed-interpolated tensorial component 4 nodes method (MITC4) is treated as a numerical analysis model for topology optimization using multiple materials assigned within Reissner-Mindlin plates. Multi-material optimal topology and shape are produced as alternative plate retrofit designs to provide reasonable material assignments based on stress distributions. Element density distribution contours of mixing multiple material densities are linked to Solid Isotropic Material with Penalization (SIMP) as a design model. Mathematical formulation of multi-material topology optimization problem solving minimum compliance is an alternating active-phase algorithm with the Gauss-Seidel version as an optimization model of optimality criteria. Numerical examples illustrate the reliability and accuracy of the present design method for multi-material topology optimization with Reissner-Mindlin plates using MITC4 elements and steel materials.

• 한국지반신소재학회논문집
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• 제20권4호
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• pp.43-52
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• 2021

국제 물류수송을 위해 연약지반에서의 항만개발이 활발하게 추진됨에 따라 항만구조물의 안정성 확보를 위해 시멘트를 원지반 흙과 혼합하여 연약지반에 직접 개량체를 형성하는 심층혼합공법의 적용도 지속적으로 이루어지고 있다. 그러나 시멘트의 경우 제품의 생산과정에서 많은 온실가스를 배출하는 문제가 있어 탄소중립이라는 국가적 목표 달성을 위해 새로운 대체재료의 개발 및 사용이 사회적으로 요구되고 있다. 이에 따라 본 연구에서는 순환자원을 재활용하여 시멘트와 유사한 경화반응을 유도할 수 있도록 개발된 CMD-SOIL을 심층혼합공법용 지반개량재로 사용하여 현장에 적용하고, 적용성을 평가함으로써 시멘트의 대체 가능성을 판단하고자 하였다. 연구결과, 설계기준강도 대비 CMD-SOIL의 압축강도는 현장 배합시험에서 1.46 ~ 2.64배, 확인보링에서 대비 1.2 ~ 5.03배 높은 수준을 나타내어 항만구조물의 안정성 확보에 요구되는 충분한 압축강도의 발현이 이루어지는 것으로 분석되었다. 또한 설계기준강도에 대한 현장에서의 압축강도의 비(λ)도 0.63 ~ 1.14로 기존의 연구결과와 유사한 결과를 나타내어 포틀랜드 시멘트, 고로슬래그 시멘트 등의 기존의 재료와 비교할 때 적용성의 차이는 없어 시멘트를 대체하여 심층혼합공법용 지반개량재로서의 사용이 가능할 것으로 분석되었다.

• 한국환경복원기술학회지
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• 제18권1호
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• pp.153-163
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• 2015

The study was conducted to develop ecological restoration method of damaged area in DMZ vicinities. As the material for the ecological restoration, forest soil and trees waste have been used. Forest soils were collected for experiments in Yanggu, Gangwon Province. Effect of ecological restoration was analyzed through germination experiment. Germination experiment was performed using 12 kinds of woody and herbaceous seeds. Woody and herbaceous seed germination in test pot was relatively evenly. Mixed material consisting of forest soil and trees waste seemed a possibility as the material for the restoration. The effects on seed germination were higher in the case of mixing more than 70% by volume ratio of local resources. Total number germinated individuals were different depending on the mixing ratio of soil sampling depth. Individual plants showed different trends depending on the experimental combination. Results of the woody seed germination were affected only in the soil sampling depth. Seed germination of herbaceous received a combined effect on soil sampling depth and mixing ratio.

• Journal of Theoretical and Applied Mechanics
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• 제3권1호
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• pp.45-65
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• 2002

A constitutive model on oorthotropic thermo-elasto-viscoplasticity for fiber-reinforced composite materials Is illustrated, and their thermomechanical responses are predicted with the fully-coupled finite element formulation. The unmixing-mixing scheme can be adopted with the multipartite matrix method as the constitutive model. Basic assumptions based upon the composite micromechanics are postulated, and the strain components of thermal expansion due to temperature change are included In the formulation. Also. more than two sets of mechanical variables, which represent the deformation states of multipartite matrix can be introduced arbitrarily. In particular, the unmixing-mixing scheme can be used with any well-known isotropic viscoplastic theory of the matrix material. The scheme unnecessitates the complex processes for developing an orthotropic viscoplastic theory. The governing equations based on fully-coupled thermomechanics are derived with constitutive arrangement by the unmixing-mixing concept. By considering some auxiliary conditions, the Initial-boundary value problem Is completely set up. As a tool of numerical analyses, the finite element method Is used with isoparametric Interpolation fer the displacement and the temperature fields. The equation of mutton and the energy conservation equation are spatially discretized, and then the time marching techniques such as the Newmark method and the Crank-Nicolson technique are applied. To solve the ultimate nonlinear simultaneous equations, a successive iteration algorithm is constructed with subincrementing technique. As a numerical study, a series of analyses are performed with the main focus on the thermomechanical coupling effect in composite materials. The progress of viscoplastic deformation, the stress-strain relation, and the temperature History are careful1y examined when composite laminates are subjected to repeated cyclic loading.

• Advances in concrete construction
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• 제11권5호
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• pp.409-417
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• 2021

The incorporation of non-biodegradable tyre waste in cement-based material has gained more interest towards sustainable construction these days. Crumb rubber (CR) from waste tyre is an alternative for sand replacement in low strength applications. Many researchers have studied CR cement-based materials produced by normal mixing (NM) method and reported a significant decrease in compressive strength due to CR. To compensate this strength loss, this research aims to study the innovative incorporation of CR in cement composite via the preplaced mixing (PM) method. In this investigation, cement composite was produced with NM and PM methods by replacing sand with 0%, 50%, and 100% CR by volume. The test results showed no significant difference in terms of densities of cement composite prepared with both mixing methods. However, cement composite prepared with PM method had lower strength reduction (about 10%) and lowered drying shrinkage (about 20%). In addition, the sound absorption coefficient and noise reduction coefficient of CR cement composite prepared by PM method were in similar range as those prepared with NM method. Overall, the results demonstrate that the PM method is promising, and the maximum replacement level of 50% is recommended for CR in the cement composite.

• 한국주거학회논문집
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• 제20권2호
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• pp.101-108
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• 2009

The purpose of this study is to develop basic data for the design of the housing space for unit that factors in the sentiment of the residents by using aesthetic elements and expression method to search for the ways to design housing space for differentiated unit. The results are as follows: First, aesthetic elements in the aesthetic element in the unit housing space for unit can be classified into basic elements and detailed elements. Second, it is possible to classify into distortion, mixing, superposition and juxtaposition methods. Third, use of the 'material' for 'wall' is recommended when designing differentiated housing space by using basic elements. At this time, expression using the method of 'mixing' is effective for inducing differentiation. In particular, elements that can perceive the difference in time are mixed, to add on slight differentiation. Fourth, 'illumination' and 'material' are used when designing differentiated housing space by using detailed elements. Fifth, preference degree of the expression method is manifested differently depending on the selected elements. Lastly, this study conducted a study on the preference level of the aesthetic elements and expression method targeting the experts alone to differentiate the design of the residential space for unit.

• 문화기술의 융합
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• 제9권5호
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• pp.557-562
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• 2023

본 연구는 순환자원을 대량 활용한 지반안정재를 터널공사 시 보조공법으로 이용하는 강관다단공법의 주입재로 활용을 검토하기 위해 다양한 주입재 배합비에 따른 겔타임, 호모겔 강도를 비교하였다. 강관다단공법은 터널의 보조공법으로써 시공 후 초기강도의 발현이 중요한 요인으로, 초기에 강도발현이 우수할수록 강관다단공법에 적합한 주입재로 활용이 가능하다. 실내시험 결과, 순환자원을 활용하는 주입재의 호모겔타임은 시멘트를 주입재로 활용하는 배합비에 비해 많은 시간이 필요한 것으로 나타났으며, 2.0MPa를 만족하는 초기강도 양생시간은 24시간 이상이 필요한 것으로 확인되었다. 따라서 순환자원 활용 주입재는 동일 배합비의 시멘트에 비해 긴 초기경화 시간이 필요한 것으로 나타났다.

• 한국지반공학회논문집
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• 제24권10호
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• pp.113-120
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• 2008

하천제방 축조를 위한 많은 양질의 성토재료는 시공헌장에서 쉽게 구하기 어려우며, 하천제방의 경제성 및 안정성에 있어서 가장 중요한 요인이라 할 수 있다. 따라서 경제적이고 안정적인 하천제방을 축조하기 위해서는 하상재료를 이용한 제방축조기술의 연구가 필수적이며 이를 위해서는 하상재료에 대하여 현장시험을 통한 설계 및 시공방법, 공학적 특성 분석이 요구되어진다. 본 연구에서는 대구 현풍천의 하상토(SP)를 대상으로 원재료 및 양질토인 화강풍화토(SW)와의 혼합에 따른 현장 다짐에 따른 공학적 특성을 평가하고 현장 혼합방법을 제시하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.57-60
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• 2006

The purpose of this study is to assess performance of prepacked DFRCC material compared with the DFRCC material which is made by using general mixing method. From 4r-point bending test, bond strength test and chlorine ion penetration test, flexural stress, -deflection relations, bond strengths, and durability assessment have been obtained. From the experiments, premixed DFRCC shows relatively good performance.