• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2859-2865
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• 2011

The welded connection is known as an essential factor for establishing qualified construction and/or maintenance of wrapped steel pipe. In this study, welded connection conditions in the coated pipes with large diameter (over 700 mm) in Korea water distribution systems were estimated for suggesting technically and economically available welded connection method. For the study analysis, current steel pipe usage and accident cases were investigated. In addition, the characteristics of each welded connection method and automatic or manual connection techniques were also compared and estimated. As results, automatic welded connection method is superior than manual welded connection method in aspect of pure construction cost (average 9%) or pure welded connection cost (average 13.5%). When the poor welding-working situations in Korea are considered such as high tolerance of out-of-roundness in KS regulation, a number of lap joint welded connections, the real cost benefits of automatic welded connection should be much higher than those of manual welded connections.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.238-239
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• 2017

Waterproofing is a very important process in terms of durability of buildings. The materials used for waterproofing work to protect the concrete structure from external deterioration factors. In particular, the waterproofing materials applied to the exterior of the concrete structure have various problems due to changes in the external environment and variables in the construction process. The waterproof layer is repeatedly dried and shrunk according to changes in the external moisture environment, and the surface may be deteriorated due to exposure to long-term sunlight. In the case of the roof waterproofing in the structure, the waterproof layer which does not have a sufficient curing period shows much swelling and floating phenomenon. These defects, such as swelling and lifting, account for most of the defects that occur in the waterproof layer of the concrete slabs. Generally, it is difficult to expect the same level of performance as the initial state even if the waterproofing work is repaired when a defect occurs. Therefore, it is possible to reduce the defects of the waterproof layer such as swelling and lifting by forming a waterproof layer which can be integrated with the concrete surface by using a polyurethane type waterproofing material having a relatively low defective ratio compared to other waterproofing materials. So in this study, the basic properties of polyurethane waterproof sheet reinforced with non-woven fabric are investigated in order to understand field applicability.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.11-15
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• 2009

Recently, a new PSC (Prestressed Concrete) bridge system, which is supported by Concrete-filled fiber-reinforced polymer (CFFRP) strut, has been introduced. This bridge is able to reduce self-weight and increase the width of traditional PSC bridges. However, no relevant research has been reported on local behavior of CFFRP strut in the bridge system. The purpose of this study is to investigate local behavior of CFFRP struts using fiber Bragg grating (FBG) sensors. Field tests were performed to examine the hoop strains and longitudinal strains of the FRP strut under various lateral positions and velocities of a test truck. It has been observed that CFFRP strut is under compression regardless of vehicle speed and location. However, the CFFRP strut is sensitive to the lateral position of vehicles in terms of strain magnitude. Results also indicated that the FBG sensors can faithfully record the hoop and longitudinal strains of the FRP strut without electro-magnetic interference.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.243-244
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• 2022

In this paper, experiments were conducted on signal amplification of polymer capsules for application to Ground Penetrating Radar so as to enable real-time monitoring of polymer capsules inside concrete using the Morphology Dependent Resonance phenomenon. A TEM CELL and a vector network analyzer were used to analyze the difference in resonance frequency depending on the material of the sphere and the presence or absence of fracture. In order to manufacture a capsule of a size that can be measured using millimeter waves used in GPR, we manufactured a capsule with a 3D printer and analyzed the effects of the presence or absence of coating and the size of the capsule on the resonance frequency. Resonant frequency or signal amplification is more affected by diameter than coating. The capsule showing the highest amplification is the resin-coated 50 mm diameter capsule with a 316-fold increase and the lowest capsule is the uncoated 10 mm diameter capsule with a signal amplification of 11.9 times. These results demonstrate the potential of GPR to measure the position and state of self-healing capsules, which are small-sized polymers, in real time using millimeter waves.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.241-242
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• 2022

Recently, related studies on the application of bacterial spores to self-healing concrete have been widely reported. Using the self-healing method of bacterial spores as a kind of pro-environment, the green method is very attractive, but because the living environment of bacterial spores is relatively harsh, it is necessary to have a way to separate the living environment of bacterial spores from the harsh external environment, And release bacterial spores when needed. Therefore, capsules are widely used in self-healing concrete. To enhance the self-healing effect, the capsules need to be evenly distributed in the concrete. Furthermore, we develop a CIP-based smart capsule with controllability. We determined the magnetic force of each capsule by mixing CIP in resin, then mass-fabricating the capsules for self-healing by a microfluidic method, and by measuring the kinetic distance of the capsules containing different amounts of cip under the action of a magnetic field strength. The results show that with the increase of the amount of cip, the active distance of the capsule also increases. When the cip is 8wt%, the active distance reaches 1.75cm. We believe this research can provide momentum for the development of self-healing capsule applications.

• Korean Architects
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• no.9 s.329
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• pp.112-115
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• 1996

강원전문대학신축설계경기의 당선작이 지난 6월21일 발표되었다. 총 9개의 작품이 응모한 이번 설계경기에서는 주.엄앤드이건축사 사무소(이각표)와 주.종합건축사사무소 산(한광호)의 공동안이 당선작으로 선정되었으며 주.건축사사무소 원.시공.형제(정상원)와, 주,건축사종합건축사사무소(공순구)의 안이 각각 우수작으로 선정되었다. 이 설계경기는 강릉시 주문진의 주문진소속고등학교 4만 8천여평 부지의 기존교사동, 실습동 증축과 대학본관, 도서관 등을 비롯 부대시설을 건립하는 것으로, 한국교육개발원의 '강원전문대설립방안 및 중.장기발전계획연구'에 의거 전문대학의 설립이념 및 목적, 설치학과 및 학생정원, 시설확충계획의 반영, 옥외시설 오픈스페이스 등을 충분히 고려하여야하는 것을 기본 설계방향으로 잡았다. 이번 심사는 한봉기(기획관), 이중근(건설교통국장)과 강원대, 관동대, 삼척산업대, 춘천교육대의 건축 및 조경학과 교수 등 총 10명이 맡았다. 당선된 주.엄앤드이건축사사무소와, 주.종합건축사사무소 산의 공동안은 적절한 조닝캠퍼스 내외의 접근성양호와 보차분리와 토지이용계획의 우수 등 여러 부분에서 심사위원들의 높은 점수를 받았다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.293-297
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• 2021

Calibration of load-resistance factors for the limit state design of front covered caisson breakwaters were presented. Reliability analysis of the breakwaters which are constructed in Korean coast was conducted. Then, partial safety factors and load-resistance factors were sequentially calculated according to target reliability index. Load resistance factors were optimized to give one set of factor for limit state design of breakwater. The breakwaters were redesigned by using the optimal load resistance factor and verified whether reliability indices larger than the target value. Finally, load-resistance factors were compared with foreign country's code for verification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.39-47
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• 2016

Repair methods of aging concrete pavement are generally used composite structure pavements, such a composite structure is subjected to a large impact on the mechanical behavior and ensure long-term commonality integrated under vehicle loads, environmental loads of the public in accordance with the bond strength between old and new concrete. A common of bonded concrete overlays that are currently available is Interface arrangements using a variety of equipment to ensure the excellent bond strength between old and new concrete than standard concrete, mixed with a material such as a polymer in order to improve the adhesion with the material itself. However, these method of constructions are being applied, depending on the developer site presents no special specifications apply when a specific application criteria objectively, this is due to the situation of each individual method, which is based on the difficulty in quality control of the site manager. In this study by performing a field test for polymer content via the variables that contribute most significantly to ensure bond strength and the field element core of the interface processing method and materials to ensure bond strength between the old and the new concrete, it was to derive the construction site construction method that can improve the performance of the bond strength through a review of the construction around the correlations and the bond strength according to the effective performance analysis of the conventional surface treatment process and variation of polymer volume fraction.

• Korean Journal of Construction Engineering and Management
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• v.6 no.1 s.23
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• pp.99-108
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• 2005

Interactive electronic technical manual(IETM) for construction projects means an electronic tool that regulations and specifications related to construction method or maintenance process ale described by electronic book type. It has a meaning of integrated information system that includes virtual reality(VR), 3D animation and image contents for representing real construction information so that user can easily understand the construction situation and maintenance process. The basic information and technical manuals of construction facilities are being written as paper documents in our construction industry. As the result, the information management in the maintenance phase of construction projects is inefficient, and maintenance cost is being increased. This study attempts to improve the lack of understanding about construction IETM through the analysis of necessity and unique function of construction IETM comparing with the IETMS in other industry, Finally, this study shows a scenario of construction IErM for mitigating natural disaster of construction facilities to verify applicability of IETM.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.403-412
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• 2018

Recently, needs for utilization of recycled aggregate have been increasing. However, its utilization has been limited due to its high alkalinity, which mostly came from the unremoved cement paste particles that were attached at the surface of recycled aggregate. Various efforts has been made to reduce its alkalinity by using $CO_2$, but currently available methods that uses $CO_2$ generate the problem with pH recovery. Considering the fact that supercritical $CO_2$ ($scCO_2$) can provide more rapid carbonation of cement paste than by normal $CO_2$, $scCO_2$ was utilized in this work. The reaction between $scCO_2$ and hydrated cement paste has been systematically evaluated. According to the results, it was found that powder type showed higher carbonation compared to that of cube specimens. It seems the carbonation by $scCO_2$ has occurred only at the surface of the specimen, and therefore still showed some amount of $Ca(OH)_2$ calcium aluminates after reaction with $scCO_2$. With powder type specimen, all $Ca(OH)_2$ was converted into $CaCO_3$. Moreover, additional calcium that came from both calcium aluminate hydrates and calcium silicate hydrates reacted with $scCO_2$ to form $CaCO_3$. After carbonation with $scCO_2$, the powder type specimen did not show pH recovery, but cube specimens did show due to the presence of portlandite.