• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.125-126
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• 2021

Fly ash, has been widely used as one of the main supplementary cementitious materials (SCMs) in the world, to replace part of cement to significantly save energy and reduce greenhouse emission. Via mechanical activation, fly ash can replace more cement without impairing early age compressive strength. This study focuses on the strength-based evaluation of carbon dioxide emission for blended cement composite containing mechanically activated fly ash. Results indicate that under similar compressive strength, a prominent drop has been witnessed in embodied energy of binary cement and CO2 emission of the composite containing mechanically activated fly ash compared with those containing ordinary fly ash.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2021년도 추계학술발표대회
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• pp.322-325
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• 2021

자율주행 자동차는 최근 들어 비약적인 발전을 거듭하고 있지만, 동시에 V2V, V2I 등 차량의 네트워킹에 따른 보안 문제에 대한 중요도 또한 함께 올라가고 있다. 이에 대비책으로 SCMS 를 중심으로 보안 기술이 발전하고 있지만, 중앙 데이터베이스에 대한 의존도는 여전히 높아 한 번의 보안 사고에도 심각한 피해가 우려되는 상황이다. 본 논문은 이러한 상황을 방지하기 위해 블록체인의 DID(Decentralized Identify, 탈중앙화 신원증명) 기술을 적용하는 방안을 설명하고, 그 예시로 긴급 차량에서의 DID 활용 방안을 제안한다.

• 콘크리트학회논문집
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• 제27권4호
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• pp.427-434
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• 2015

이 연구의 목적은 다양한 혼화재를 기반으로 목표 $CO_2$ 저감율 뿐만 아니라 콘크리트 초기 슬럼프, 공기량 및 28일 압축강도와 같은 종래의 요구 사항을 만족하는 $CO_2$ 저감 콘크리트의 합리적인 배합 설계 절차를 확립하는 것이다. $CO_2$ 배출과 콘크리트의 압축강도에 혼화재가 미치는 영향을 평가하기 위해, 실내 배합 및 레미콘 공장 데이터(전체 12537 배합표)를 분석하였다. 콘크리트의 배합에 따른 $CO_2$ 배출량 평가를 위해 고려된 시스템 경계는 재료 채취 및 가공에서부터 레미콘 공장에서 콘크리트 생산단계까지이다. 구축된 12537 콘크리트 배합 데이터를 사용한 비선형 회귀 분석을 통해 혼화재의 종류 및 치환율, W/B, S/a와 같은 콘크리트 배합 설계를 결정할 수 있는 간단한 모델식을 제시하였다. 또한, 주어진 콘크리트 배합에 대한 $CO_2$ 배출량은 제안된 모델식을 이용하여 직접 계산 될 수 있다. 결국, 개발된 배합 설계 절차는 레미콘 분야에서 $CO_2$ 저감 콘크리트의 초기배합표를 결정하는데 효율적으로 이용될 수 있다.

• 한국건설순환자원학회논문집
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• 제4권3호
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• pp.292-298
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• 2016

본 연구에서는 매스 매트 콘크리트에 있어, 상 하부를 구분하여 타설하는 실무조건을 고려하여, 상부 및 하부배합의 혼화재 종류와 치환율을 동일 및 달리하는 배합 조건 변화로부터 최적치를 도출한 다음, 실구조체에 적용하여 해석치와 실측치간을 비교하므로서, 혼화재를 활용한 매스콘크리트의 효율적인 수화열균열 저감방안을 제안하고자 하였다. 연구결과 먼저, 현장적용 전 사전검토를 위해 Midas gen을 이용하여 수화열 해석을 실시한 결과 상부는 OPC : FA = 85 : 15 배합, 하부는 OPC : FA : BS = 50 : 20 : 30 배합을 본 대상 구조물 매스 매트콘크리트의 최적배합으로결정하였다. 이를 적용한 실제 현장의 시험결과 슬럼프, 공기량 및 압축강도는 모두 목표범위를 만족하였다. 또한, 봄철 실제 현장의 매스 매트콘크리트의 온도특성으로 최적배합의 경우는 중심부의 최고 온도 약 $59^{\circ}C$, 표층부 온도 약 $49^{\circ}C$로 나타나, 약 $10^{\circ}C$의 온도차가 나타났으며, 수화열 해석결과 약 1.4의 균열지수를 나타내었다. 따라서, 실무를 고려한 매스 매트콘크리트의 경우 상 하부 타설 콘크리트간의 저발열 배합정도를 달리 고려하는 수화발열량차 공법적용은 침하균열 방지 및 수화열 균열제어에 효과적인 방법이 될 것으로 사료된다.

• Advances in concrete construction
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• 제2권3호
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• pp.163-176
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• 2014

Essentially, when electrical current flows easily in concrete that has large pores filled with highly connective pore water, this is an indication of a low resistivity concrete. In concrete, the flow of current between anodic and cathodic sites on a steel reinforcing bar surface is regulated by the concrete electrical resistance. Therefore, deterioration of any existing reinforced concrete structure due to corrosion of reinforcement steel bar is governed, to some extent, by resistivity of concrete. Resistivity of concrete can be improved by using SCMs and thus increases the concrete electrical resistance and the ability of concrete to resist chloride ingress and/or oxygen penetration resulting in prolonging the onset of corrosion. After depassivation it may slow down the corrosion rate of the steel bar. This indicates the need for further study of the effect of electric arc furnace dust (EAFD) addition on the concrete resistivity. In this study, concrete specimens rather than mortars were cast with different additions of EAFD to verify the electrochemical results obtained and to try to understand the role of EAFD addition in influencing the corrosion behaviour of reinforcing steel bar embedded in concrete and its relation to the resistivity of concrete. The results of these investigations indicated that the corrosion resistance of steel bars embedded in concrete containing EAFD was improved, which may link to the high resistivity found in EAFD-concrete. In this paper, potential measurements, corrosion rates, gravimetric corrosion weight results and resistivity measurements will be presented and their relationships will also be discussed in details.

• Journal of Magnetics
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• 제21권3호
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• pp.330-339
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• 2016

A magnetic field sensing system with a single primary sensor and multiple reference sensors deployed locally and orthogonally, was proposed for downlink signal reception and interference cancelling for Through-the-Earth Communication (TEC). This paper mathematically analyzes a design optimization process for a search coil magnetometer (SCM), and applies that process to minimize the bandwidth of the primary SCM for TEC signal reception and the volume of reference SCMs for multiple distributions. The primary SCM achieves a 3-dB bandwidth of 7 Hz, a sensitivity threshold of 120 fT/${\surd}$Hz, and a volume of $2.32{\times}10^{-4}m^3$. The entire sensing system volume is as small as $10^{-2}m^3$. Experiments with interference from industrial frequency harmonics demonstrated an average of 36 dB and 18 dB improvements in signal-to-interference ratio and signal-to-interference plus noise ratio, respectively, using multichannel recursive-least-squares algorithm. Thus, the proposed sensing system can reduce the interference effectively and allows reliable downlink signal reception.

• Advances in concrete construction
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• 제5권3호
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• pp.241-255
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• 2017

Concrete is known to be the most used construction material worldwide. The environmental and economic aspects of Ordinary Portland Cement (OPC) containing concrete have led research studies to investigate the possibility of incorporating supplementary cementitious materials (SCMs) in concrete. Metakaolin (MK) is one SCM with high pozzolanic reactivity generated throughout the thermal activation of high purity kaolinite clay at a temperature ranging from $500^{\circ}C$ to $800^{\circ}C$. Although many studies have evaluated the effect of MK on mechanical properties of concrete and have reported positive effects, limited articles are considering the effect of MK on durability properties of concrete. Considering the lifetime assessment of concrete structures, the durability of concrete has become of particular interest recently. In the present work, the influences of MK on mechanical and durability properties of concrete mixtures are evaluated. Various experiments such as slump flow test, compressive strength, water permeability, freeze and thaw cycles, rapid chloride penetration and surface resistivity tests were carried out to determine mechanical and durability properties of concretes. Concretes made with the incorporation of MK revealed better mechanical and durability properties compared to control concretes due to combined pozzolanic reactivity and the filler effect of MK.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1170-1177
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• 2006

We apply VRP(Vehicle Routing Problem) to sludge collection system in this study. Sewage stores of villages are located in each village around a multipurpose dam. Sludge which is produced in sewage store of village is transported from the sewage store of village to the sewage treatment plants by the special purpose vehicle such as the tank lorry. In this paper, we propose sludge collection strategies which allocate each sewage store of village to sewage treatment plants and decide the schedule of sludge collection in order to collect sludge efficiently. The strategies aim to decrease transportation cost with deciding proposed vehicle routing and scheduling the sludge collection. When we decide route of vehicles, we consider the collection time in sewage store of village, distance between sewage store of villages and vehicle information as average velocity of vehicle, operation time of vehicle driver. We also develop the SCMS(Sludge Collection Management System) based on windows system with real data which is used in certain circumstance. And we experiment to figure out vehicle route and transportation cost throughout changing input data.

• Advances in concrete construction
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• 제10권5호
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• pp.417-429
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• 2020

Waste glass is a global solid waste with huge reserves. The discarded waste glass has caused a series of problems such as resource waste and environmental pollution, so it is urgent to recycle waste glass with high replacement level. Glass powder (GP), as a supplementary cementitious material (SCM), used in cement-based materials has already become one of the important ways to recycle waste glass mainly attributed to its pozzolanic reaction and filling effect, especially to the suppressed ASR expansion. This paper demonstrates an overview of the properties of GP and its effect on the fresh and mechanical properties of cement-based materials. The study found that the influence of GP on the performance of cement-based materials mainly depends on its content, particle size, color and type, curing conditions, and other SCMs. Finally, based on the problems involved in the investigation of concrete containing GP, some corresponding suggestions and efforts are given to further guide the utilization of GP in cement-based materials.

• Advances in Computational Design
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• 제3권3호
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• pp.289-302
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• 2018

The use of optimum content of supplementary cementing materials (SCMs) such as limestone filler (LF) to blend with Portland cement has been resulted in many environmental and technical advantages, such as increase in physical properties, enhancement of sustainability in concrete industry and reducing $CO_2$ emission are well known. Artificial neural networks (ANNs) have been already applied in civil engineering to solve a wide variety of problems such as the prediction of concrete compressive strength. The feed forward back propagation (FFBP) algorithm and Tan-sigmoid transfer function were used for the ANNs training in this study. The training, testing and validation of data during the backpropagation training process yielded good correlations exceeding 97%. A parametric study was conducted to study the sensitivity of the developed model to certain essential parameters affecting the compressive strength of concrete. The effects and benefits of limestone filler on hardened properties of the concrete such as compressive strength were well established endorsing previous results in the literature. The results of this study revealed that the proposed ANNs model showed a high performance as a feasible and highly efficient tool for simulating the LF concrete compressive strength prediction.