• 한국구조물진단유지관리공학회 논문집
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• 제3권2호
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• pp.205-212
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• 1999

Recently, unexpected cracks in the concrete deck slab of composite steel bridges have been widely reported at an early age of concrete placing due to the concrete placing sequence and methods. Accordingly, the analytical research was carried out to verify the negative moment at an internal supports due to the several concrete pouring sequence and to determine the reasonable concrete placing method on the deck slab of composite steel bridge. The results show that the conventional concrete-placing method, which pours concrete first on the positive moment regions and then negative regions, leads to the minimum moment at an internal supports. However, the conventional method produces two impractical construction joints on every spans and makes field engineer to pour concrete continuously. In conclusion, this concrete-placing method was verified to be reasonable only when the construction joint was placed at the $\frac{5}{8}l{\sim}\frac{6}{8}l$ location of the middle span.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.835-840
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• 2000

The purpose of this study is developing concrete Mixing & placing method that could be adjusted to vertical joint at top-down method. Basic test was consists of general, high fluidity, and high quality mixing concretes and Mock-up test had several placing ways, placing positions. They were examined several placing ways, placing positions with Mock-up model comparison with three mixing concrete to know fluidity characterics. Used with Mock-up model to know packing ability from placing ways and positions. The result of the study like this; High fluidity and High quality concretes show favorable packing ability, especially, in sheath placing way. It was expected to good result in next planned real structure test.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.841-846
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• 2000

The purpose of this study is promote perfect of construction and progress of packing ability through comparison and analysis with quality, as placing ways and placing direction are changed. Kinds of concrete are general, high fluidity, and high performance concrete. Classified with concrete as placing ways - direct ways, sheath way - and placing directing - flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2002년도 학술논문발표회
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• pp.37-40
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• 2002

The purpose of this study is promote perfect of construction and progress of packing ability through comparison and analysis with quality, as placing ways and placing direction are changed. Kinds of concrete are general, high fluidity, and high Performance concrete. Classified with concrete as placing ways - direct ways, sheath way - and placing directing - flange direction, web direction - is analyzed section and strength of hardened concrete. The results of this study is belows the more fluid of concrete, the more useful to top-down method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.141-146
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• 1999

An experimental study is carried out to estimate the effects of mixing and placing condition on the mechanical properties of anti-washout concrete. According to the test results, mixing method and placing temperature do affect the characteristics of rrsh concrete, while they do not affect the strength development of anti-washout concrete. But, concrete strength was greatly affected by the placing condition and placing height. Concrete strength decreases linearly as the placing height increased. Compared to the normal concrete, the increase in strength is not associated much with an increase in the elastic modulus of anti-washout concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.128-131
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• 2004

This paper is to investigate the mock up test results of mass concrete for transfer girder using setting time difference with super retarding agent(SRA) to reduce hydration heat. According to test results, the temperature history of plain concrete without placing lift had a steep rising curvature, and plain concrete had a big temperature difference between surface and middle section of mass concrete, which may result in occurrence of temperature crack. However, considering placing method B, because setting time of middle section concrete was retarded with an increase in SRA contents, higher hydration heat temperature was observed at surface section concrete compared with that at middle section concrete at early age, which can lower the possibility of hydration heat crack. In case of placing method C, although peak temperature of hydration heat was much lower, at early age, high crack occurrence possibility of the hydration heat attributable to the big temperature difference between middle section and bottom section of concrete was expected at bottom section concrete. Therefore, the structure above the ground like transfer girder is not applicable to consider the placing method C.

• 한국컴퓨터산업학회논문지
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• 제9권3호
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• pp.99-104
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• 2008

매스콘크리트에서 수화열에 의한 응력은 외기온도와 콘크리트의 타설온도에 따라 변하므로 이들의 영향을 고려한 해석이 필요하다. 본 연구에서는 교각의 코핑부를 대상으로 해석을 수행하여 분석하였다. 최대 인장응력은 타설 후 2.75일을 전후하여 표면 모서리부에서 발생하며 균열지수는 계속 증가하여 균열 발생 가능성은 거의 없는 것으로 나타났다. 그리고 계절에 관계없이 콘크리트의 타설온도를 낮추면 수화열에 의한 균열 발생 가능성을 줄일 수 있는 것으로 나타났다. 따라서 콘크리트를 타설하기 전에 타설온도를 낮추기 위한 여러 가지 방안을 강구하면 수화열에 의한 균열을 최소화할 수 있다.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제6권5호
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• pp.223-228
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• 2017

SMT는 전자 부품을 흡착하여 PCB상에 정확히 실장 하는 장비이다. 이를 위해서는 중간 위치에 설치된 카메라 앞에서 정지하여 비전 검사를 한 후 실장 위치로 이동한다. 그 이동 경로의 타입은 16가지가 되며, 본 논문에서는 (sLa-Camera-pLa)타입에 대한 3가지 경로의 구동 시간을 비교하였다. 첫 번째는 비전 검사를 위해 카메라 앞에서 정지한 후 실장 하는 방법(stop-motion), 두 번째는 카메라 앞에서 정지하지 않고 움직이면서 비전 검사를 한 후 실장하는 방법(fly1-motion), 세 번째는 X축과 Y축이 최고의 높은 속도를 갖도록 한 후 비전 검사를 하고 실장하는 방법(fly2-motion)이다. 3가지 방법에 대한 구동 시간을 계산하여 비교한 결과 모두 동일한 시간이 걸리는 것을 알 수 있었다. 따라서(sLa-Camera-pLa)타입은 장비 구조의 변경 없이 stop-motion방법으로도 가장 빠른 시간에 실장할 수 있음을 확인하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.391-396
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• 2001

Exposed concrete execution is utilized insufficiently due to surface honecomb and undesirable appearance by entrapped air when existing placing method is applied. Therefore, surface glossing and impact properties of cement mortar incorporating fiber glass net blast furnace slag, expansive admixture and Polypropylene fiber are investigated in order to develop precast exposed concrete pannel by dry construction method. The kinds of the forms, placing method and admixture contents are varied. According to test results, surface glossing decrease with elapse of age. Considering the form kinds, surface glossing with acryle + astage shows the best performance. Placing horizontally shows positive results in reducing surface defects such as honecomb. Impacting resistance shows the best performance when glass fiber net applied, due to the enhance in toughness and absorption of impact.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.369-376
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• 2001

As many studies have performed to reduce thermal cracking in mass concrete, it is already prepared against thermal cracking, we can find many plans against thermal cracking in several reference book. But it needs practical guidelines to be available in construction site. In this study to establish control method of thermal cracking in mass concrete, tests which have factors of placing thickness and curing method of concrete are performed.