• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.25-26
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• 2023

Free-form buildings serve as landmarks, and interest and demand are increasing. However, in the case of free-form concrete members, different curved surfaces are required depending on the location where they are used, and the formwork is custom-made and used. Concrete is poured into the manufactured formwork to produce FCP (Free-form Concrete Panel). However, since it is an atypical building that requires precise curvature, compaction cannot be performed after concrete is poured. This leads to the occurrence of bughole, which reduce the strength and aesthetics of concrete. Therefore, in this study, we intend to conduct basic experiments to develop a magnetic compaction device that can be used for FCP. As a result of the experiment, it was confirmed that the bug hole was improved when the magnetic compaction device was applied, and there was no significant difference in compressive strength and flexural strength. This technology can be used in the field of Free-form concrete where it is difficult to perform compaction work, and it is expected to be used as a basic research related to technology for new automatic compaction.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.86-86
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• 2018

볼트, 너트 등의 파스너는 건축 재료나 기계부품을 고정하는 데 사용하는 기계요소로, 건축, 철도, 조선 등 전 산업분야에 걸쳐 사용되고 있다. 그 중 스테인리스 소재의 볼트, 너트는 뛰어난 내식성과 저렴한 가격으로 널리 사용되고 있는데, 소재의 특성 및 작업현장의 상황, 온도의 변화 등의 원인에 의해 고착현상(galling)이 발생한다. 고착현상이란 성분 혹은 표면경도가 비슷한 금속의 나사산을 조이는 과정에서 발생하는 압력의 증가 및 마찰력에 의해 냉간 용접(cold welding)이 일어나는 것으로 나사산의 표면이 눌어붙게 된다. 이러한 고착현상은 스테인리스 소재에서 많이 발생하는데, 한번 발생한 후에는 비파괴 해소가 불가능한 상태가 되어 경제적 손실을 야기한다. 이러한 고착현상의 해소를 위해 본 연구에서는 주석과 알루미늄을 사용한 새로운 열 확산 코팅 기술을 개발하고 이를 304 스테인리스강에 적용하여 열처리 온도에 따른 특성변화를 확인하였다. 열 확산 코팅을 위해 팩 세멘테이션 방법을 이용하여 아르곤 분위기 하에서 열처리 하였고, 온도는 $200{\sim}250^{\circ}C$에서 코팅을 수행하였다. 이에 따른 코팅 전과 후의 표면 및 단면 분석을 통해 성공적으로 코팅층이 형성됨을 확인하였고, 온도가 증가함에 따라 코팅성분의 양이 증가하는 현상을 보임을 알 수 있었다. 또한, 고착방지성능을 확인하기 위하여 ASTM G196-08 시험을 통해 코팅조건에 따른 고착현상을 분석하였으며, 그 결과 기존에 코팅되지 않은 304 스테인리스강보다 고착현상이 개선됨을 확인하였다. 따라서 304 스테인리스강 소재의 볼트, 너트 제품에 주석-알루미늄 코팅층을 적용시키면 기존의 고착현상을 개선하고 서비스 품질을 향상시킬 수 있을 것으로 판단된다.

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.137-145
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• 2010

The mechanical properties of stone structures are generally characterized according to the strength of the stone used. An ultrasonic velocity method that does not damage cultural heritages is used to measure the strength of stone. However, there is no correction involved for surface roughness and thickness of the stone in the ultrasonic method currently used. In addition, a contact agent such as grease can cause contamination on the surface of a cultural heritage. Accordingly, this study suggests an indirect method of strength estimation formula for stone structures based on the surface roughness of the structure, its thickness, and the type of contact agent. (1) Rock strength estimation formula using ultrasonic velocity method of dabbed finish : $f_{su}=30.51\;Vp^{0.82}(R^2=95)$ (2) Rock strength estimation formula using ultrasonic velocity method of harsh finish : $f_{su}=61.52\;Vp^{0.32}(R^2=92)$.

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.51-57
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• 2018

The objective of the present study is to examine the feasibility on the development of high-insulation concrete using aerogels with hydrophilic surface treatment. To prevent the segregation and enhance the dispersibility of agerogels in the cement pastes, the substrate of aerogels was modified to be hydrophobic property using surfactant. The modified aerogels were added from 0% to 100% of the cement volume at the interval of 25% under the constant cement content. Some cement pastes showed segregation phenomenon and flocculation of aerogels during mixing phase. The addition of aerogels decreased the compressive strength of cement pastes but enhanced the thermal conductivity. The thermal conductivity of pastes with 100% aerogels was lower by 43% when compared with that measured in the conventional paste. To improve the compressive strength and insulation capacity of concrete containing aerogels, a reliable surface treatment method of aerogels needs to be further investigated.

• Proceedings of the Korea Society of Design Studies Conference
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• 2004.05a
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• pp.280-281
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• 2004

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.45-55
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• 2010

Recently a number of media facade buildings making beautiful cityscape landmark has been increased in Seoul. However, indiscreet adaptation of media facade cause problems such as light pollution and poor city image. This paper was to investigate luminous characteristics of media facade building. Five representative media facade buildings in Seoul have been selected. The CS-100 and ProMetric-1400 were used to measure the luminance and color temperature of the facades. The measurement points were located at the opposite spot of the building. The results showed that maximum media facade luminance of such buildings exceed Seoul design guideline. Also, color temperature with over 5,500[K] that exceed the design guideline were mostly used in all the facades.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.169-179
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• 2012

Microbiological calcium carbonate precipitation (MCCP) is being applied for the aesthetic restoration of cement buildings destroyed by biochemical processes and to block water penetration into the cement's inner structure. After determining the advantages of this technique, many related studies in the area of architecture concerning the application of microorganisms to improve construction material have been reported in both America and Europe. The techniques compatibility with cement material is especially interesting because of the needed screening of various calcium carbonate forming-bacteria and the required development of their application methods. The purpose of this review is to describe the mechanism of MCCP and related researches with eco-friendly construction materials. Mainly, we describe the methodological studies focused on biodeposition on the surface of building materials and the research trends concerning the addition of microorganisms to improve the durability of cement structures. Additionally, the concepts and technical aspects focused on the development of self-healing smart concrete, with the use of multi-functional bacteria, have been considered.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.794-801
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• 2003

As it is important to measure the degree of the deterioration and predict service life caused by chloride in concrete structure the methods of measuring chloride in the concrete is raised important problems. This study is to set a new standard for using of the colorimetric method through grasping the character of the colorimetric distinction method, and measuring the chloride content at the place discolored. Also, to predict chloride content around embeded bar and time reaching limit chloride concentration through measuring the chloride content of concrete surface by colorimetric distinction method and this study presents the new concept of concrete degradation and diagnosis of the durability by salt damage. According the results, it is possible to use colorimetric distinction method as simplified measurement to measure the fixed quantity of the chloride concentration. What is more, it would make calculation of concrete surface chloride had a wide fluctuation at the general environment extended. Also, it would be make estimating durability of reinforced concrete structures applied to the basic data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.257-261
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• 2022

Additive manufacturing (AM, also known as 3D printing) applied to the construction industry is implemented and verified for various effects since advantages such as high design freedom, improving worker safety, and predictable construction period. However, due to the low maturity compared to the existing technology, studies are underway to solve new problems that occur in the overall of AM technology. In this paper, we confirm the effect of low construction surface flatness on the stacked features in the process of on-site AM construction. In particular, unstable AM features are determined through quantitative analysis by laser scanning, and a construction strategy is proposed for the surface flattening.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.187-187
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• 2015

Polyvinylidene fluoride (PVDF) 코팅은 뛰어난 내후성으로 인해 Pre-painted metal에 많이 응용되며 주로 고가의 건축물 외장재에 적용되고 있는데, 수지의 열가소성 특성으로 인해 도막경화시 Baking 온도 및 냉각속도가 도막의 결정화도에 영향을 주어 가공특성이 상이하게 변함을 확인 하였다.