The thermal conductivity (TC) of graphene-based/metal composites is currently not satisfactory because of the existence of large interfacial thermal resistance between graphene and metal originating from the strong scattering of phonons. In this work, 6063Al-alloy-based reduced graphene oxide (rGO) composite with strong covalent bonds interface was prepared via self-assembly, reduction, and electrophoresis-deposition processes by using 3-aminopropyl triethoxysilane (APTS) as a link agent. Structural characterizations confirmed the successful construction of strong Al-O-Si-O-C covalent bonds in the as-prepared 6063Al-Ag-APTS-rGO composite, which can promote the transfer of phonons in the interface. Benefiting from the unique structure, 6063Al-Ag-APTS-rGO (214.1 W/mK) showed obviously higher cross-plane TC than 6063Al (195.6 W/mK). Comparative experiments showed that 6063Al-Ag-APTS-rGO has better cross-plane TC than 6063Al/Ag/ APTS/rGO (196.6 W/mK) prepared via physical mixing of stirring process, evidencing the significance of electrophoresisdeposition (EPD) process on constructing strong covalent bonds for improving the heat dissipation performance. Besides, the effects of different rGO contents and test temperature on the TC of the composites and their corrosion resistance were also discussed. This work demonstrated a feasible strategy for the construction of metal–carbon interface composite with improved thermal performance.

CFRP(Carbon Fiber Reinforced Polymer)는 강재 대비 약 4배의 강도와 25% 수준의 경량성을 보 유한 신소재 복합재료이며, 부식과 같은 화학적 반응에 대한 저항성이 우수하다. 이러한 특징으로 인 해 전 세계적으로 부식에 취약한 철근의 대체재로써 연구가 활발하게 진행 중이다. 국내에서 적용되고 있는 CFPR 보강재에 대한 성능 평가의 경우, 재료의 단편적인 물성치 조사를 통한 단기 성능 평가(인 장 등)에 초점을 두고 수행되고 있어, 보강된 RC(Reinforced Concrete) 구조물 내 장기 거동 특성(피 로 등)이 반영된 CFRP 보강재 자체의 성능 검증이나 품질 기준이 전무한 실정이다. 이에 따라 본 연 구에서는 기존의 단기 성능 평가 방법의 한계를 극복하고자 선행 연구를 바탕으로 건설 산업 분야에 서 상용화된 건설용 CFRP의 장기 거동 특성을 규명하는 것을 목적으로 한다. 이를 위해 RC 구조물 내 ‧ 외부에 보강된 CFRP 보강재의 실제 하중 환경을 모사하기 위해 ASTM D7772 및 D6272를 바 탕으로 4점 휨 시험 기반 휨-인장 피로 시험 장비를 개발하였으며, 섬유 함침율이 50%인 CFRP 시편 을 대상으로 3, 5, 7, 9mm의 변위 하중을 고려하여 보강재의 장기 거동 분석 및 피로 성능 한계 곡 선(r-N curve)을 구성하였다. FRP의 피로 거동은 유효 응력이 감소하다 일정 수준에서 일정하게 유지 된다는 특징을 보인다. 따라서 선행 연구를 참고하여 CFRP 시편의 피로 파괴를 초기 응력이 80% 감 소된 시점으로 정의하여 피로 시험을 시행하였다. 시험 결과, CFRP 보강재의 피로 거동은 하중이 급 격하게 감소하는 영역(영역 I), 변곡점 이후 감소가 미미한 영역(영역 II), 변곡점 이후 감소가 미미한 영역(영역 III)으로 구분되었다. 평균적으로 약 105 사이클까지 영역 I를 보였으며, 이후 영역 II와 영역 III가 순차적으로 나타남을 확인하였다. 이러한 시험 결과를 바탕으로 r-N curve를 구성하였으며, 이 를 기준으로 상용 CFRP 보강재의 피로 성능 합불 여부를 평가할 수 있다.

In recent automobile development, vehicle weight reduction has become a very important goal. Seat weight reduction is a large portion of vehicle weight reduction. In this study, a specimen tensile tests were conducted on the Almag material, which is an alloy of aluminum and magnesium, and also conducted on SAFH440, SAFH 590, SAFC780, and SAFH980, which are mild steel materials used in the seat frame. The tensile specimen tests were carried out in two speed; 2mm/s and 4mm/s, and the obtained stress to strain curve was converted to the analysis material card of true stress to true strain curve to be used in the seat structural analysis. The constructed analysis material card was used in the specimen tensile finite element analysis, and the analysis result was able to obtain the stress to strain curve similar to the test result.

PURPOSES : In this study, an eco-friendly mastic asphalt backfill material is developed to reduce production and construction temperatures by 40 ℃ compared with those recorded when using conventional hot-mix mastic asphalt backfill materials. METHODS : To reduce the production and construction temperatures, SIS polymer modifiers and gum rosin were selected, and gum rosin-modified SIS materials were applied to the mastic asphalt binder mix design. SIS is less viscous than SBS at high temperatures owing to its thermal characteristics, and incorporating gum rosin into SIS causes the latter to exhibit a loose and soft structure. To improve the performance of the mastic asphalt modified with SIS and gum rosin, three different filler mixes, i.e., 100% PMMA, 50% PMMA and 50% calcium carbonate, and 40% PMMA and 60% calcium carbonate were applied. RESULTS : The rosin-modified SIS reduces the viscosity of the developed mastic asphalt binders. In particular, incorporating 3.7% of gum rosin is beneficial to the mastic binder and does not degrade its low-temperature performance. Similarly, using 100% PMMA as a filler improves the performance but results in workability issues at high temperatures. CONCLUSIONS : Rosin-modified SIS and PMMA are promising alternatives for increasing the workability at high temperatures while maintaining the target performance of grade PG82-22 binders if the appropriate ratio of calcium carbonate is mixed with PMMA and an alternative filler comprising calcium carbonate is used.

현장에서 양생 또는 고형화 과정을 거치는 일반 시멘트 콘크리트, 자가다짐 시멘트 콘크리트, 아스팔트 콘크리트, 고분자 개질 혼합물과 같은 도로포장 재료의 유동 특성은 시공시점에서의 환경조건과 함께 도로포장 구조물의 초기 성능을 결정하는 중요한 요소이다. 따라서 재료의 양생이 완료되는 시점까지 포설 및 다짐에 영향을 미치는 재료의 유동 특성을 검토하는 것은 기존 혼합 및 포설 장비의 개선뿐만 아니라 새로운 장비의 개발을 통한 시공과정 개선 및 최적화를 위해서도 매우 중요한 과정이라 할 수 있다. 또한 건축 또는 토목 구조물의 시공 및 유지관리에 활용되는 건설정보 모델링이 향후 부재의 역학적 거동과 연계된 시공 및 유지관리를 포함하는 통합적인 수준으로 발전될 것임을 고려할 때, 경험에서 벗어나 실험적으로 검증된 역학적 기반의 설계 및 시공 방법을 제시하는 것은 매우 중요한 의미를 갖는다. 건설재료의 유동은 그 최종 형태에 따라 순수전단 유동, 신장유동, 이들의 중간 정도에 해당하는 유동의 3가지로 구분하여 분석적 해를 유도할 수 있다. 그러나 분석적 해를 활용하는 방법은 비교적 단순한 경계조건에 대한 재료의 유동적 특성을 예측하는데 유용하게 활용될 수는 있으나, 경계조건이 복잡해질수록 해를 계산하는 것이 거의 불가능하여 컴퓨터를 활용한 수치해석 기법을 적용하는 것이 합리적이다. 한편 유동성 재료의 동적 거동을 해석하는 방법으로는 이산요소법이나 전산유체역학(computational fluid dynamics, CFD)을 활용할 수 있는데, 입자형 재료 사이에 존재하는 유체의 양이 상대적으로 적어 입자와 입자 사이 또는 입자와 경계조건과의 상호작용이 중요하게 고려되어야 할 경우에는 이산요소법이 바람직한 반면, 시멘트 페이스트와 같이 균질의 재료로서 연속체의 특성을 나타내는 경우에는 CFD를 활용하는 것이 바람직한 것으로 알려져 있다. 본 연구에서는 연속체로 가정할 수 있는 유동성 재료의 시간에 따른 거동을 예측하기 위한 CFD의 활용성을 평가하고자 하였다. 이를 위하여 미니콘 실험에 대하여 분석적 해와 CFD를 활용한 결과를 비교하여 수치해석에 활용된 가정과 모형의 타당성을 검증하였으며, 검증된 모형을 활용하여 주요 입력변수에 대한 민감도 분석을 수행하여 시간에 따른 재료의 슬럼프와 퍼진 정도의 변화를 확인하였다.

Companies build the factory automation system to improve management effectiveness and productivity as prime strategies for sustainable growth. But most companies undergo various trials and errors while carrying out the project without elaborate preparation stage for factory automation. In this study, we tried to verify what factors are critical to effectively building distribution automation system, which is a branch of factory automation system. A consulting model for setting up a Material Handling Automation System by utilizing the Stage-Gate Process, which is product development process was studied. 29 material handling automation projects carried out between the year 1990 to 2013 at K-Company were selected. Interviews with the project managers, operators and maintenance personnels, various records and current status of the projects were used as data for structural equations based on the Milan consulting model and existing researches of factory automation, CIM for material handling automation. Creating effective basis of production, material handling system and energy saving system with expert review, when preparing a material handling automation project, help promote the project planning thus contributing to the performance of the resulting system, which appears though rather weakly in our data. Also the effect of material handling automation can be enhanced through sufficient and effective links to the relevant environments such as production logistics management and automated warehouses. More detailed planning characteristics of project promotion or some time-series data of effective Material Handling Automation System could enhace furthur studies. We propose a consulting model for setting up an efficient material handling automation system.

Recent News patrons of incidents can be called sinkhole that occurred one after another (Sink Hole). Due to this anytime, anywhere I do not know how the land is turned off worry and anxiety is the reason why you can never be dismissed as exaggerated. As we have seen today through the video, the vehicle was traveling on a road or pedestrian who was walking down the street they look out of the basement of a sudden they still come to mind vividly. Here, examples and corresponding measures to prevent the sinkhole off the ground, including the causes and impact on society because of this that occurred, and policy measures and abroad are evaluated with respect to what it is.

본 연구는 고상폐기물인 준설토와 혼합물질인 점토 및 유리프리트를 이용하여 기능성을 갖는 건축자재용으로의 재활용 가능성을 검토하고자 실시되었다. D항만 준설토의 중금속 함량은 Zn이 526.0~13,150.1 mg/kg의 범위를 나타내는 등 심한 오염상태이었다. 준설토(30P)의 주요 화학조성은 SiO₂(48.30 wt%), Al₂O₃(16.60 wt%), CaO(10.10 wt%), Fe₂O₃(7.75 wt%)이었으며, 점토는 SiO₂가 70.82 wt%, Al₂O₃ 18.78 wt%, 유리프리트는 SiO₂가 71.75 wt%, CaO 13.99 wt%, Na₂O 8.51 wt% 함유되어 있었다. 준설토를 점토에 10~40 wt% 첨가한 후 1,000℃와 1,100℃에서 소성한 시편의 압축 강도는 각각 132.6~178.5 kgf/cm2와 581.2~793.7 kgf/cm²이었다. 준설토가 40 wt% 첨가된 경우 (SC46) 1,100℃에서 소성한 경우가 793.7 kgf/cm²로 1,000℃에서 소성한 경우의 153.0 kgf/cm² 보다 5배 이상 높게 나타나 1,100℃ 온도가 소성에 더 적합한 것으로 판단되었으며, KS 1종벽돌 기준을 만족시켰다. 또한, 시편의 용출시험 결과 폐기물관리법상 지정폐기물 판정기준치를 크게 하회하는 것으로 나타났다.

This is to show some basic data for introducing both circulated aggregate and recycled powder producing waste concrete. Standard-mixing design for 24MPa has been basically used and added and replaced normal aggregate with recycled powder made of waste concrete. In addition, polycarboxylate high-range water reducing agent has been used because recycled powder is missing adhesive strength and it is not compare with cement's adhesive strength. Compressive strength with powder mixture of 2%, 4%, 6%, 8%, and 10% has been decreased down to 80% of normal concrete material strength without recycled powder mixture. 200℃, 400℃ and 600℃ heated concrete were compressively tested in order to find out concrete strength resistant to high temperature. heat capacity was also tested, based on the expectancy of its low conductivity. In addition, thermal conduction test was tested in order to find out concrete insulation. According to this test, when concrete was tested by fire resistance, it using the circulation aggregate was same resulted by concrete using the natural aggregate. also, recycle powder was not effecting insulation performance. but it is fit to standard on concrete insulation of building law.

140 buildings of Korean major cities were investigated for the presence of asbestos and man made mineral fibers (MMMF) in their construction materials. 73 (52%) and 84 (60%) buildings contained asbestos and MMMF in their construction materials, respectively, and 17 (12%) buildings contained both asbestos and MMMF. 75% of the asbestos containing buildings were mostly constructed during 1970's. 100% of underground shopping arcades, 90% of manufacturing workplaces, 84% of train and bus terminals had the asbestos containing construction materials. The manufacturing workplaces of Daejeon (89%) and Daegu (89%), which mostly had been built in the past, used asbestos containing building materials, while the building in Seoul, Busan and Jinju, which were constructed recently, used relatively lower asbestos containing building materials with 46%, 28%, and 33%, respectively. 9 building materials that have been widely used in Korea were analyzed using a transmission electron microscope equipped with energy dispersive X-ray analyzer (TEM-EDX) for their mineral contents. All asbestos fibers showed typical characteristics of chrysotile fibers with hollow tube structure. The average diameter ranged from 0.03㎛ to 0.05㎛, and the average length were ranged from 7.5㎛ to 12.0㎛. Atomic percentages of asbestos fibers were 51.9∼55.9% of Mg, 41.3∼44.3% for Si, and 2.7∼4.8% for Fe.

화력발전소 전기집진기에서 포집되는 FA(Fly ash)는 재활용률이 높으나 화력발전소 노에 떨어지는 BA(Bottom ash)는 FA에 비해 매우 낮은 편이다. 또한 FA에 대한 연구는 활발하게 진행되고 있는 반면 BA에 대해서는 매우 저조하다. 한편 지속적으로 건축 공사 수요가 있지만 건축 재료를 과거처럼 용이하게 그리고 저렴하게 공급 받기는 더욱 어려워지고 있는 실정이므로 BA를 건축 재료로 활용할 수 있게 하는 연구는 매우 유용할 것으로 판단된다. 따라서 본 연구에서는 재활용률이 저조하여 처리에 부담이 되었던 BA를 최대한 재활용할 수 있도록 건축 재료로 연구 개발하여 BA 재활용률을 높일 뿐만 아니라 BA 처리의 부담을 줄이고, 또한 저렴한 건축 재료를 용이하게 다량 확보할 수 있도록 화력발전소에서 발생한 BA가 건축 재료로 갖고 있는 다양한 특성에 대하여 연구하였다. 화력발전소에서 발생한 BA를 건축 재료로의 특성에 대하여 연구를 진행한 결과 타 재료에 비해 경량성과 단열성이 매우 우수함은 물론 원적외선 방사률 등도 비교적 우수하게 나타났다.

In this study, the recycling processes of construction and demolition waste (C&D waste) were analyzed, and its national recycling rate was determined using material flow analysis (MFA). Available statistical data provided by Ministry of Environment and Korea Environment Corporation were used for the MFA study. The collected data were carefully examined and validated by field investigations. System boundary for MFA covered from waste generation from construction sites to final disposal in 2013. The field investigation showed that recycled aggregate is produced through mechanical shredding, separation, and screening processes of C&D waste. The production efficiency (or process yield) was estimated to be approximately 81.2% on average. The foreign materials in the waste accounted for 18.8% by weight. The separated impurities were sent to recycling facilities, incineration facilities, or landfill sites, depending on the physicochemical characteristics. Efficiency of recycling facilities and the statistical data were integrated to estimate the national actual recycling rate, which turned out to be 87.7% in 2013. Approximately 49.1% of the construction-related waste was recycled as recycled aggregate for concrete production and road base layer for asphalt pavement. Based on the result of MFA, there is 9.8% difference between the actual recycling rate in this study and reported recycling rate by national statistics. In the future, more various C&D waste treatment and disposal facilities, along with aggregate recycling facility, should be investigated to verify the actual recycling rate determined by this study. Statistical accuracy should be further refined through additional field investigations. Our findings can be applicable to development of recycling policies and best management practices for C&D waste streams.

It is required development on the work process of the legal system, quality management and safety management for safety securement of construction. Therefore, this study examines the status and issues surrounding the current legal systems and proposes improvements of material for safety securement of construction.

Carbon dioxide generated from construction materials and construction material industry among the fields ofconstruction is approximately 67 million tons. It is about 30% of the carbon dioxide generated in the fields of construction.In order to reduce carbon dioxide in the fields of construction, it is necessary to control the use of fossil fuel consumedand decrease carbon emission by reducing the secondary and tertiary curing generating carbon dioxide in constructionmaterial industry. Therefore, this study manufactured mortar by having cement as the base and substituting three bindingmaterials up to 50% and then adopted different curing methods to analyze congelation and strength characteristics. According to the result of strength characteristics by the types of binding materials and replacement ratio, the specimensubstituting ESA (Early Strength Admixture) and FPC (Fine Particle Cement) showed active strength improvement. Inparticular, the specimen substituting ESA as 25% indicated the greatest strength improvement, and as the number of curingincreased, the strength grew higher, too. And when the binding material was used by substitution, it showed strengthcharacteristics similar to or higher than the specimen conducting tertiary autoclave curing as the secondary steam curing.