• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.401-402
• /
• 2023

The shear connection of the vertical construction joint of a slurry wall by the concrete shear key has excellent structural performance and is economical and eco-friendly. However, technology for forming concrete shear keys in the underground is still underdeveloped. This paper proposes the development of the construction technology required to form a concrete shear key at the vertical construction joint of the slurry wall.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.140-141
• /
• 2018

There are three types of high fluidity concrete: powder based, VMA based, and combined. In the case of the powder based high fluidity concrete mixture, according to the textbook, increased viscosity due to the replaced fly ash can prevent segregation of coarse aggregate. On the other hand, decreased density of the powder due to the fly ash replacement can causes segregation but there is no report on this issue. Therefore, in this research, the segregation resistance and segregation evaluation method for powder based high fluid concrete mixture are evaluated. As a result, with increased replacing ration of supplementary materials, EIS value was decreased and apparently segregation resistance was increased. However, from the compressive strength evaluation depending on height of the cylindrical specimen, it was confirmed that the different of strength difference between top and bottom part of the specimen. Thus, following research regarding vertical segregation should be studied.

• Magazine of the Korean Society of Hazard Mitigation
• /
• v.7 no.1 s.24
• /
• pp.156-170
• /
• 2007

• Geotechnical Engineering
• /
• v.40 no.1
• /
• pp.36-42
• /
• 2024

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.3
• /
• pp.11-20
• /
• 2022

The main purpose of this study is to investigate the applicability of the shear wave tomography technology as a non-destructive testing method to evaluate the debonding between the track concrete layer (TCL) and the hydraulically stabilized based course (HSB) of concrete slab tracks for the Korea high-speed railway system. A commercially available multi-channel shear wave measurement device (MIRA) is used to evaluate debonding defects in full-scaled mock-up test specimen that was designed and constructed according to the Rheda 200 system. A part of the mock-up specimen includes two artificial debonding defects with a length and a width of 400mm and thicknesses of 5mm and 10mm, respectively. The tomography images obtained by a MIRA on the surface of the concrete specimens are effective for visualizing the debonding defects in concrete. In this study, a simple image processing method is proposed to suppress the noisy signals reflected from the embedded items (reinforcing steel, precast sleeper, insert, etc.) in TCL, which significantly improves the readability of debonding defects in shear wave tomography images. Results show that debonding maps constructed in this study are effective for visualizing the spatial distribution and the depths of the debondiing defects in the railway concrete slab specimen.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1450-1451
• /
• 2015

우리나라는 지난 '96년 제정한 "전력기술관리법"에 따라 전력시설물 공사에 대한 설계와 감리업무를 실시하고 있지만 "전기공사업법", "정보통신공사업법" 등에서처럼 건축 등 타 분야와의 분리발주를 명확하게 명시하고 있지 않아 발주자, 시공자, 용역업자 등 업계의 혼란을 가중시키고 있어 많은 문제점을 야기시키고 있는 것이 현실이다. 분리발주는 통합발주에 비해 각 공정별 기술력을 확보하고 중소업체와 대형업체간의 공정한 경쟁을 유도함으로써 전력산업 시장경제의 건전성을 확보하는 등 통합발주로 인해 발생시키는 불법하도급, 업계의 혼란, 타 분야와의 경쟁력 약화 등 부정적인 요소를 해결할 수 있는 방안이다. 하지만 법상에서 명확하게 명시하고 있지 않아 모든 전기설계 감리 용역에 대해 분리발주가 되고 있지 않은 것이 현실이므로 거시적 관점에서 전력산업의 미래를 본다면 분리발주가 필요할 것으로 사료된다.

• Journal of the Korea Institute of Building Construction
• /
• v.16 no.5
• /
• pp.447-453
• /
• 2016

Recently, the design and supervision separating system has have been widely adopted in Korea. In this system, the owner should exclude the architect who designed the building from supervisor in the same project. The design and supervision separating system has advantage of less fraudulent construction and weakness of design intention reflection difficulty in construction stage. In this study, the status, problems and solutions of this system are identified from expert survey and interview. The main results of this study are as follows. First, the work scope of designer and supervisor should be clear and the guidelines for this system should be clearly defined. Second, the optimal price for the work scope should be guaranteed. Also, the education program for the improvement of supervisor capability should be provided.

• Journal of the Korean Society for Railway
• /
• v.18 no.6
• /
• pp.543-551
• /
• 2015

Quick-hardening track (QHT) is a construction method which is used to change from old ballast track to concrete track. Sufficient time for construction is important, as the construction should be done during operational breaks at night. Most of the time is spent on exchanging the ballast layer. If it is possible to apply the ballast non-exchange type of quick-hardening track, it would be more effective to reduce the construction time and costs. In this paper, pouring materials with high permeability are suggested and a construction method involving a layer separation pouring process considering the void condition is introduced in order to develop ballast non-exchange type of QHT. The separate pouring method can secure the required strength because optimized materials are poured into the upper layer and the lower layer for each void ratio condition. To ensure this process, a rheology analysis was conducted on the design of the pouring materials according to aggregate size, the aggregate distribution, the void ratio, the void size, the tortuosity and the permeability. A polymer series was used as the pouring material of the lower layer to secure the void filling capacity and for adhesion to the fine-grained layer. In addition, magnesium-phosphate ceramic (MPC) was used as the pouring material of the upper layer to secure the void-filling capacity and for adhesion of the coarse-grained layer. As a result of a mechanics test of the materials, satisfactory performance corresponding to existing quick-hardening track was noted.

• Journal of the Korea Institute of Building Construction
• /
• v.20 no.5
• /
• pp.399-407
• /
• 2020

The aim of the research is to provide the boundary conditions for segregation of normal strength grade and high fluidity concrete mixture (so called mid-fluidity concrete) with rheology parameters. Since the normal strength grade concrete mixture has a relatively high water-to-cement ratio and no SCMs, it is easy to be segregated when superplasticizer is added. Hence, to achieve the mid-fluidity concrete of normal strength grade and high fluidity, preventing segregation of the mixture is inevitable. In this research, using two superplasticizers with different solid concentrations, the flow behaviors and rheological behaviors were assessed by increasing fluidity until the segregation happened. According to the experiment in this research, an unusual behavior in rheology parameters was observed when the concrete mixture started to be segregated. From this results and report, it is expected to contribute on the definition of segregation with rheological test methods.

• 월간 기계설비
• /
• s.294
• /
• pp.81-89
• /
• 2015

행정안전부는 지난해 12월 19일 지방계약 예규 개정사항을 공포하고 올해 1월 5일부터 시행에 들어갔다. 특히 분리발주 공사의 범위 명확화 및 활성화 등 지난해 11월 24일 공포된 지방계약법 시행령의 개정사항이 지방계약 예규에 반영됐다. 이번 예규 개정을 통해 공종을 분리 시공하는 것이 효율적이라고 인정되는 공사를 구체적으로 규정하고 분할 분리발주 대상을 사전에 검토토록 함으로써 중소업체의 입찰참여 기회가 더욱 확대될 전망이다. 분리발주 법제화는 대한설비건설협회에서 정부, 국회를 비롯해 제18대 대선후보캠프에 지속적으로 건의한 결과 박근혜 정부가 40대 중점 국정과제로 확정해 추진한 결과로서 지난해 국가계약법 시행령을 비롯해 지방계약법 시행령에 명문화됐다. 한편 이번 정부는 지방계약 예규 개정을 통해 공동수급체 구성원 중 일부업체가 입찰무효인 경우 전체가 입찰 무효처리 되던 불합리한 규정을 바로잡았으며, 중소기업의 경영난 해소를 위해 소규모 계약에 대해서도 선금을 지급토록 했고, 여성 및 장애인 기업에 대한 혜택도 늘렸다. 뿐만 아니라 어려운 경제 사정을 고려하여 중소기업의 입찰 참여 확대를 위해 제한경쟁 입찰에서 재무상태 제한 규정을 폐지했으며, 계약비리 근절 및 협상계약 남용 방지 위해 수의계약 사유공개 및 사전검토 등 기준을 강화했다.