• Computers and Concrete
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• 제4권6호
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• pp.425-436
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• 2007

This study is mainly focused on applying Fuller's ideal gradation curve to theoretically design blended ratio of all solid materials of a reactive powder mortar (RPM), also known as reactive powder concrete (RPC), with the aid of error function, and then to study the effect of fly ash/slag on the performance of RPM. The solid particle is assumed to be spherical particles. Then, the void volume of paste ($V_{\nu}$) and the paste content with specific quality can be obtained. As conclusion, under Fuller's ideal grading curve, the amount of fly ash/slag mixture is higher than that with silica fume along due to it better filled the void within solid particle and obtains higher packing density.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 1999년도 춘계학술대회 발표논문집
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• pp.69-69
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• 1999

• Journal of Welding and Joining
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• 제13권4호
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• pp.65-74
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• 1995

The weld seam tracking sensor is indispensable to improve the flexibility of automatic arc welding systems. Among the position sensing methods available, a laser displacement sensor is one of the most prevailing methods. In this study, a laser displacement sensor was examined on detecting the weld seam of lap joints in sheet metal arc welding. The output signal of the laser displacement sensor may ontain severe fluctuation from the effect of arc light, spatters, fume, etc. So a variety of signal processing methods was applied to smooth the output signal of the sensor. And then the weld joint was determined by using the central difference method. It was revealed that the quadratic mean method plays an important role in detecting the weld seam during welding especially.

• Structural Engineering and Mechanics
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• 제52권1호
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• pp.97-113
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• 2014

In the present work appropriate concrete material models have been proposed to predict drying shrinkage and specific creep of High-performance concrete (HPC) using Artificial Neural Network (ANN). The ANN models are trained, tested and validated using 106 different experimental measured set of data collected from different literatures. The developed models consist of 12 input parameters which include quantities of ingredients namely ordinary Portland cement, fly ash, silica fume, ground granulated blast-furnace slag, water, and other aggregate to cement ratio, volume to surface area ratio, compressive strength at age of loading, relative humidity, age of drying commencement and age of concrete. The Feed-forward backpropagation networks with Levenberg-Marquardt training function are chosen for proposed ANN models and same implemented on MATLAB platform. The results shows that the proposed ANN models are more rational as well as computationally more efficient to predict time-dependent properties of drying shrinkage and specific creep of HPC with high level accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1284-1287
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• 1996

전기도금공장 ANODE 투입 및 추출 자동화 사업은 ANODE 자동투입 Robot이 개발되어 적용되기전까지는 국내에서 적용된 사례가 전혀 없었고 선진제철소에서 일부 적용된 사례가 있는 것으로만 알고 추진되었던 사업이다. 이번에 개발하여 현장에 적용한 ANODE 자동투입 robot은 가반중량이 300kg이나 되는 이동형 특수 robot으로 국산화개발품이지만 성능의 신뢰성이 입증되지 않는 상태에서 추진되었기 때문에 위험 부담성이 컸으며 완전자동화가 되기까지 많은 시행착오를 겪었다. 시행착오의 주요원인으로는 현장여건 즉 설비의 간섭, FUME에 의한 robot의 고장 또한 robot 자체의 설계 miss등 무수히 많았다. 이번 ANODE 자동투입 robot 개발 및 현장 적용으로 향후 확대 적용시 시행착오에 의한 문제점을 최소화 할수 있는 대책을 수립할수 있는 좋은 기회가 주여져 96.12.E 준공을 목표로 2차분 ANODE투입 자동화 사업이 진행중에 있으며 1차분과 시스템을 통합하여 보다 완벽한 자동화시스템을 구축할 예정이며 97년도에는 포항제철소로 확대 적용할 예정이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.265-268
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• 1999

In this study, we manufactured the ultra-high strength concrete using mineral admixture which is easily workable. From the test results of compressive strength, It is concluded that the proper replacement ratio of silica fume should not exceed to 10% and the replacement of slag is more effective that the replacement of fly ash to gain very high compressive strength. Thermal stress analysis is conducted to find the way of controlling the thermal crack of ultra-high strength concrete. As results of thermal stress analysis, it was found that reducing placing temperature of concrete(pre-cooling) is effective to reduce thermal crack and placing concrete in high air temperature is more effective than placing concrete in low air temperature.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.461-466
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• 2000

To improve the quality of concrete, we usually consider the reduction of water/cement ratio, the increase of concrete cover depth and the use of mineral admixtures. Reportedly, the use of admixtures make concrete more durable and tighten against water. But, it is needed to study more about the relationship between the admixtures and the chloride ion diffusion. Therefore, in this study, we focused on the chloride ion diffusion properties of the pozzolanic admixtures such as fly-ash, slag and silica fume which are known as being useful on chloride attack resistance when mixed into mortar or concrete. Furthermore, we treed to analyze the correlation between mortar and concrete using the admixture, which is useful for analyzing chloride ion diffusion mechanism.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.529-532
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• 2006

This paper presents results from creep and shrinkage tests performed on different High Strength Concrete (HSC) mixes (with compressive strengths up to 90 MPa). Results were compared with those from various Code prediction models. The effects of pozzolanic materials on the creep and shrinkage were also investigated. Results show that while fly ash increases the compressive creep of concrete, silica fume decreases it. Moreover, current creep and shrinkage prediction models need to be revised for the HSC mixture.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.41-44
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• 2006

Recently, single shell lining method of construction is studied by economical method of construction to make use of high-performance shotcrete of permanent shotcrete lining concept in the UStA, Europe, Japan etc. High-performance shotcrete use is essential as permanent support that single shell lining method of construction has two functions of lining and support to shotcrete. In this research, optimum accelerator amount was decided after setting time test using alkai-free and cement mineral accelerator. Also replacement ratio of silica fume and fly-ash was determined.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.45-48
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• 2006

Generally, the strength of concrete depends on factors of materials, mix proportions, compaction, manufacturing methods and curing and so on. This is an experimental study to compare and analyze the influence of cementitious material type on the compressive strength of ultra high strength concrete. For this purpose, the mix proportions of concrete according to the type of cementitious materials(Fly ash, blast furnace slag, silica fume) and W/B(31.5, 27.5%) was selected. And then air content, slump-flow, O-lot, compressive strength test were performed.