• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.67-70
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• 1992

1930년 스웨덴에서 개발에 성공, 네덜란드에서 더욱 발전시킨 ALC(Autoclaved Light-weignt Concrete의 약칭) 는 가볍고, 견고하고, 그리고 시공이 간편한 경제적인 요건들을 충족시키는 건축자재로 세계적으로 널리 사용되고 있으며 , 국내에서는 불과 수년 전부터 연구 개발되고 있는 실정이다. ALC 란 시멘트와 규사, 생석회등 무기질 원료를 고온,고압으로 증기 양생시킨 경량의 기포 콘크리트 제품을 통칭한 것이다. ALC공정은 bulk ALC를 생산하는 batch공정과 이 bulk ALC에 대한 처리 공정으로 크게 나눌 수가 있으며 여기에서는 bulk ALC 처리 공정을 side shield treatment, anti-corrosion treatment, curing grate transferer, cutting station, curing car transportation, autoclave traveling platform, 및 packing 의 공정으로 세분하여 각 공정개요 소개 및 PLC(Programmable Logic Controller의 약칭)를 이용한 제어 system에 대하여 설명하고자 한다.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.192-197
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• 1996

An experimental study was performed to examine the feasibility of using silicic wastes as construction materials for civil structures, and investigate its utility as a replacement for the favored nature resource to prevent the economic loss. In order to achieve this objective, mechnical properties of concrete containing silicic wastes is tested by investigating the strength development through parameters of water-binder ratios replacement 10 percent ratio with respect to curting conditions. The effect of stringth development is investigated for curing conditions when silicic wastes of 10 percent of cement-binder ratios is containde. Comparision on compressive strength of normal concrete and concrete containing silicic wastes at 28 day is conducted. The concrete with silicic wastes have larger compressive strength than of normal concrete by about 20 percent, when cured at 80 degree. The wastes concrete using silica sand shows increased strength, fracture toughness, elastic modulus and strain than the normal concrete, although the silicic wastes concrete could be able to satisfy the generally required strength for conventional concrete structures.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.59-65
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• 2004

동제련 공정중 Smelting에서 SiO2가 없으면 산화에 의한 생성물은 Molten Cu-Fe-O 'Oxysulphide' 와 Solid Magnetite가 된다. 이 생성물은 Cu-rich Liquid와 Cu-dilute Liquid로 분리가 불가능하다. Smelting의 목적이 Cu가 높은 Matte와 산화된 불순물의 효과적인 분리에 있으므로 이와 같은 분리가 불가능한 혼합상태를 분리해 주어야 한다. 이때 SiO2가 첨가되면 Cu-rich 상인 Matte가 FeO-rich상인 Slag로의 분리가 가능해진다. 이러한 의미에서 동제련에 있어서 규사의 성분은 매우 중요하며 현재 재생사를 규사로 대체 사용하고 있다. 한편 실리콘 모노머 합성 공정인 금속 규소와 접촉 물질(Contact Mass, 구리촉매와 조촉매)을 반응시켜 (Si+CH3Cl ${\rightarrow}$ (CH3)2SiCl3) 실리콘 모노머를 생산하는 공정중 반응이 끝난 접촉물질인 구리 폐촉매가 발생되는데 주요성분이 Cu 12%, Si80%로 재생사와 유사하여 동제련에 투입 가능 여부를 판단하기 위하여 각 공정에서의 용융실험을 통하여 결론을 도출하였고, 실 조업 Test를 거쳐 처리하게 되므로 구리 회수 및 폐기물로써의 매립을 중지 할 수 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.175-176
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• 2013

Nowadays, energy-saving has become important in the construction industry. Above all things, outside insulation on buildings is important in measure of energy-saving. However, its insulation performance is degraded by the problem of that Cement-polymer modified waterproof coatings are used mostly for covering plaster mortar. In this study, we examine the optimum size of the silica and how does silica's size effect on physical properties of outside insulation covering plaster mortar.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.287-295
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• 2010

In this study, ordinary Portland cement was used and the air void was minimized by using minute quartz as the filler. In addition, steel fibers were used to mitigate the brittle failure problem associated with high strength concrete. This study is in progress to make an Ultra-high strength powdered concrete (UHSPC) which has compressive strength over 300 MPa. To increase the strength of concrete, we have compared and analyzed the compressive strengths of the concretes with different mix proportions and curing conditions by selecting quartz sand, dolomite, bauxite, ferro silicon which have diameters less than 0.6 mm and can increase the bond strength of the transition zone. Ultra-high strength powdered concrete, which is different from conventional concrete, is highly influenced by the materials in the mix. In the study, the highest compressive strength of the powdered concrete was obtained when it is prepared with ferro silicon, followed in order by Bauxite, Dolomite, and Quartz sand. The amount of ferro silicon, when the highest strength was obtained, was 110%, of the weight of the cement. SEM analysis of the UHSPC showed that significant formation of C-S-H and Tobermorite due to high temperature and pressure curing. Production of Ultrahigh strength powdered concrete which has 28-day compressive strength upto 341MPa has been successfully achieved by the following factors; steel fiber reinforcement, fine particled aggregates, and the filling powder to minimize the void space, and the reactive materials.

• Journal of Conservation Science
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• v.25 no.4
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• pp.439-450
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• 2009

The purpose of this study is to find out characteristics of the fillers made by epoxy resin (L-30) and filling epoxy resin (L-50) with talc, quartz sand and wollastonite with different mixture ratio of 5%, 50%, 80%, 120%, and 150%. The viscometer and colorimeter were used to measure the viscosity and chromaticity of the fillers. Additionally, IC and SEM were used to reveal characteristics of the filler, and checked ultrasonic wave velocity, compressive strength and contact angle to estimate the stability between the filler and stones which are essential for conservation treatments. The filler mixed with the talc had the lowest value in the ultrasonic wave velocity analysis, and its compressive strength decreased as the mixing rate of talc increased. On the other hand, wollastonite had higher values than others in the ultrasonic wave velocity and the compressive strength regardless of epoxy resin type, also, these values increased as mixing rate increased. The properties of the filler, which include the granularity and shape, have influence on characteristics of the stone conservation adhesives. Thus, the filler type, characteristic, and mixture ratio must be considered for effective conservation treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.118-125
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• 2017

In this study, we examined the bond performance of FRP Hybrid Bars. FRP Hybrid Bars are developed by wrapping glass fibers on the outside of deformed steel rebars to solve the corrosion problem. The surface of the FRP Hybrid Bars was coated with resin and silica sand to enhance its adhesion bonding performance with concrete. Various parameters, such as the resin type, viscosity, and size of the silica sand, were selected in order to find the optimal surface condition of the FRP Hybrid Bars. For the bonding test, FRP Hybrid Bars were embedded in a concrete block with a size of 200 mm3 and the maximum load and slip were measured at the interface between the FRP Hybrid Bar and concrete through the pull-out test. From the experimental results, the maximum load and bond strength were calculated as a function of each experimental variable and the resin type, viscosity and size of the silica sand giving rise to the optimal bond performance were evaluated. The maximum bond strength of the specimen using epoxy resin and No. 5 silica sand was about 35% higher than that of the deformed rebar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.178-184
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• 2017

This study was aimed to investigate the tensile behaviors of PE(Polyethylene) fiber-reinforced highly ductile cementitious composites with different combinations of micro silica sand and normal sand(river sand) with maximum particle size of 4.75 mm. Flow test result indicated the increase of flowability with higher replacement ratio of river sand. There was no noticeable difference in the mean compressive strength with different replacement ratio of river sand, but the variation in the compressive strength increased as higher amount of river sand was adopted for the replacement. The difference in the uniaxial tensile strength was negligible, but the tensile strain capacity was significantly influenced by the replacement ratio of river sand. It is thought that increased density of multiple cracks induced improved tensile strain capacity when higher percentage of river sand was adopted for fine aggregate. The deviation in the strain capacity increased as the replacement ratio of river sand was higher, as in the compressive strength. This study presented the feasibility of using normal sand instead of micro silica sand for highly ductile cementitious composites with equivalent or better uniaxial tensile performance, even though it might increase the deviation in the performance.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.330-337
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• 2021

3D printing is not only at the fundamental study and small-scale level, but has recently been producing buildings that can be inhabited by people. Buildings require a lot of cost and labor to work on the form work, but if 3D printing is applied to the building, the construction industry is received attention from technologies using 3D printing as it can reduce the construction period and cost. 3D printing technology for buildings can be divided into structural and non-structural materials, of which 3D printing is applied to non-structural materials. Because 3D printing needs to be additive manufacturing, control such as curing speed and workability is needed. Since cement mortar has a large shrinkage due to evaporation of water, cement polymer dispersion is used to improve the hardening speed, workability, and adhesion strength. The addition of polymer dispersion to cement mortar improves the tensile strength and brittleness between the cement hydrate and the polymer film. Cement mortar using polymer materials can be additive manufacturing but it has limited height that can be additive manufacturing due to its high density. When light-weight materials are mixed with polymer cement mortar, the density of polymer cement mortar is lowered and the height of additive manufacturing, so it is essential to use light-weight materials. However, the use of EVA redispersible polymer powder and light-weight materials, additional damage such as cracks in cement mortar can occur at high temperatures such as fires. This study produced a test specimen incorporating light-weight materials and EVA redispersible polymer powder to produce exterior building materials using 3D printing, and examined flame resistance performance through water absorption rate, length change rate, and cone calorimeter test and non-flammable test. From the test result, the test specimen using silica sand and light-weight aggregate showed good flame resistance performance, and if the EVA redispersible polymer powder is applied below 5%, it shows good flame resistance performance.

• Journal of Korea Foundry Society
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• v.3 no.3
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• pp.167-173
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• 1983

The effect of sand grain size on the various properties of mold is not only basic but important interest which we have to deal with.And the relation among the various properties of mold (strength, permeability, flowability, compactability, hardness, deformation, toughness etc.) is very complicated and inaccurate, so we can delineate the behavior of mixture (sand+water+bentonite) with experience only. Within recent years a so-called rigid-water theory has been accepted as a means of advancing logical explanations for the research aimed at delineating sand-clay-water relationships. By changing grain size or mesh no. of grain, specimens have been subjected to green compressive strength, permeability, deformation, flowability, compactablity, toughness at room temperature. Under constant mulling energy and ratio of water/bentonite, the results obtained were as follows: 1. With decreasing grain size green compressive strength of the specimen increased. 2. With decreasing grain size permeability decreased. 3. With decreasing grain size flowability and bulk density decreased but compactability increased. 4. With decreasing grain size deformation decreased but toughness increased. 5. At 60 mesh no., the properties of specimen are conspicuously changed. The reason is that the total surface area of sand grain which affects the type of bonding between sand grains is more changed at 60 mesh number.