• 한국건축시공학회지
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• 제16권1호
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• pp.45-52
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• 2016

본 연구에서는 무시멘트 결합재(NCB)를 사용한 지반 그라우팅용 약액주입재의 B액 결합재의 종류, 결합재의 W/B 및 A액과 B액의 부피비에 따른 겔타임 및 호모겔강도의 변화 특성을 검토함으로써 무시멘트 결합재의 지반 그라우팅용 결합재로서의 적용 가능성을 검토하고자 하였다. 무시멘트 무기결합재는 당사에서 공동연구를 통해 개발된 시멘트를 대체할 수 있는 고로슬래그 기반의 친환경 무기결합재로서 화학조성비가 다른 NCB-1, 2, 3을 사용하여 실험을 진행하였다. 실험 및 현장 적용성 분석 결과, 겔타임 및 호모겔강도의 요구성능을 확보할 수 있는 결합재 종류별 W/B 및 A액과 B액의 부피비가 도출되었으며, W/B가 100~140%, A : B가 50 : 50~30 : 70인 조건에서 급결구간 및 중결구간의 경우 NCB가 OPC 대비 동일한 겔타임 수준에서 호모겔강도의 확보가 유리한 것으로 평가되어 NCB의 지반 그라우팅용 결합재로서의 적용이 가능할 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.853-856
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• 2008

경량기포 콘크리트는 건축물 방바닥의 단열, 차음 및 높이차 조정 등의 목적으로 아파트 건설공사 등에 주로 이용되고 있다. 그러나 기존의 경량기포 콘크리트는 소포에 의한 체적감소, 과다한 균열 발생등의 문제점을 가지고 있는데 이를 보완하기 위해 콘크리트 제조에 사용되는 혼화재들을 첨가하여 특수한 특성을 가지는 경량기포 콘크리트용 개량분체가 개발되었다. 그러나 아직도 기포율 저감 및 균열방생등과 같은 문제점이 제기되고 있어 이를 보완하기 위한 연구가 필요한 실정이다. 따라서, 본 연구에서는 선행연구를 통한 개발된 경량기포 콘크리트의 실무적용 가능성에 대하여 분석하고자 실구체로 상정한 모의부재를 제작 후 경량기포 콘크리트를 타설하여 이들의 제반 공학적 특성을 분석함으로써 실용화 가능성을 검토하였는데, 그결과는 다음과 같다. 각종 재료가 혼입된 개량분체인 플레인은 약 230mm의 플로우치를 보여 목표 플로우치를 만족하였고, 100mm부재에서 약 4mm의 침하가 일어나 OPC에 비하여 약 2배의 침하깊이 감소효과를 나타냈다. 강도면에서는 OPC가 가장 높은 강도로 나타났으나, 세 수준 모두 KS기준 0.5품의 규정치를 상회하는 강도이었다. 건조수축 균열에 대한 부재균열 분석으로써 플레인은 약 0.1mm정도로 건조수축 균열에 매우 우수한 것으로 나타났다.

• 한국조경학회지
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• 제28권5호
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• pp.48-57
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• 2000

This paper is dealing with the fundamental properties of planting concrete, replacing the existing cover concrete on the roof of a building. This study is to find out the physical characteristics of the planting concrete and rearing characteristics of the grass throughout the modeling experimental materials. As the results of the experiment, the physical properties of planting concrete show the following results; when the paste to aggregate ratio is 0.2~ 0.4, voids volume : 30~17%, unit weight: 1,710~2,010kg/m3, compressive strength : 45~145kgf/$\textrm{cm}^2$, its pH is more than 11, but is reduced to the proper degree for planting after being neutralized. Kentucky bluegrass covered with planting concrete is grown well. The planting concrete used with blast furnace slag cement shows a better properties at the height, the width and the covering rate by 1.1cm, 0.5mm and 7%, respectively, than those used with ordinary portland cement. Also, the less the paste to aggregate ratio is, the better the plant grows. The orders of the effects of temperature control are as follows; the system of planting concrete with grass>the system of planting concrete without grass>the system of mixed soil>the existed roof system. In case, the planting concrete is placed to the roofs of buildings instead of normal concrete slab, and a number of favorable effect can be expected such as the improvement os environmental factors, the reduction of construction cost, the saving of energy and the reduction of environment load. The future research on the change of a variety of the aggregate conditions and the application of the practical structures should be made, and also the research of the endurance also be performed.

• 한국실내디자인학회논문집
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• 제22권2호
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• pp.220-229
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• 2013

Recently, the volume of knowledge information in the form of electronic media is quickly increasing in the library field along with the advancement of electronic communication technology. Libraries have both printed data and electronic data and are faced with the issue of corresponding with the access and use of knowledge information in terms of the space. This study is for building the layout of a sustainable knowledge information space based on the view that the library is the official infrastructure of the knowledge information based society. It is intended to analyze the meaning of knowledge information in the modern society, characteristics in the spatial organization and the transmission of knowledge information. The goal of this study is to understand and forecast the spatial structure where users access knowledge information and exchange with one another and developing the direction and guidelines for the spatial plan that today's libraries prefer through this analysis. For this, this study firstly prepared the base for the research on library space which can be considered as the physical realization of such concepts, through the theoretical review about the knowledge information and social concepts as well as characteristics of modern society. Also, it seized the characteristics in the transmission of knowledge information by conducting a structural analysis of the information service such as knowledge information and space, space and information media, space and space through the cases of 10 public libraries. The analysis resulted in basic data including the system of organizing knowledge information, system of knowledge information transferring elements and structure, and layout pattern of each library. These results are deemed meaningful for the promotion of communication with the user through the exchange, creation, and experience of knowledge information, the social role of today's public library.

• Steel and Composite Structures
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• 제51권3호
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• pp.271-288
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• 2024

The primary objective of this study is to investigate the production and performance characteristics of structural concrete incorporating varying proportions (0%, 25%, and 50% by volume) of pumice stone, as well as aluminum lathe as an additive at 0%, 1%, 2%, and 3%, under fire conditions. The experiment will be conducted over a period of up to 1 hour, at temperatures ranging from 24℃, 200℃, 400℃ and 600℃. For the purpose of this, a total of twelve test samples were manufactured, and then tests of compressive strength (CS), splitting tensile strength (STS), and flexural strength (FS) were performed on these samples.Next, a comparison was made between the obtained values and the influence of temperature. To achieve this objective, the manufactured samples were placed at temperatures of 200℃, 400℃, and 600℃ for a duration of 1 hour, and were subjected to the influence of temperature.These values at 24 ℃ were then contrasted with the CS results obtained from test samples that were subjected to the temperature effect for an hour at 200 ℃, 400 ℃, and 600 ℃. A comprehensive analysis of the test outcomes reveals that the incorporation of aluminum lathe wastes into a mixture results in a significant reduction in the compressive strength of the concrete. As a result of this adjustment, the CS values dropped by 32.93%, 45.70%, and 52.07%, respectively. Furthermore, It was shown that testing the ratios of pumice stone alone resulted in a decrease in CS outcomes. Additionally, it was found that the presence of higher temperatures is clearly the primary factor contributing to the decrease in the strength of concrete. Due to elevated temperatures, the CS values decreased by 19.88%, 28.27%, and 38.61% respectively.After this investigation, an equation that explains the connection between CS and STS was provided through the utilization of the data of the experiments that were carried out.

• Computers and Concrete
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• 제21권3호
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• pp.249-259
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• 2018

The use of recycled aggregate in concrete is gaining much attention due to the growing need for sustainability in construction. In the present study, Self Compacting Concrete (SCC) is made using both natural and recycled aggregate (crushed recycled concrete aggregate from building demolished waste) and performance of recycled aggregate based SCC for the bond behaviour of reinforcement is evaluated. The major factors that influence the bond like concrete compressive strength (Mix-A, B and C), diameter of bar ($D_b=10$, 12 and 16 mm) and embedment length of bar ($L_d=2.5Db$, $5D_b$ and full depth of specimen) are the parameters considered in the present study in addition to type of aggregates (natural and recycled aggregates). The mix proportions of Natural Aggregate SCC (NASCC) are arrived based on the specifications of IS 10262. The mix proportions also satisfy the guidelines of EFNARC. In case of Recycled Aggregate SCC (RASCC), both the natural coarse and fine aggregates are replaced 100% by volume with that of recycled aggregates. These mixes are also evaluated for fresh properties as per EFNARC. The hardened properties like compressive strength, split tensile strength and flexural strength are also determined. The pull-out test is conducted as per the specifications of IS 2770 (Part-1) for determining the bond strength of reinforcement. Bond stress versus slip curves were plotted and a typical comparison of RASCC is made with NASCC. The fracture energy i.e., area under the bond stress slip curve is determined. With the use of recycled aggregates, reduction in maximum bond stress is noticed whereas, the normalised maximum bond stress is higher in case of recycled aggregates. Based on the experimental results, regression analysis is conducted and an equation is proposed to predict the maximum bond stress of RASCC. The equation is in good agreement with the experimental results. The available models in the literature are made use to predict the maximum bond stress and compare the present results.

• 한국건설관리학회논문집
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• 제6권1호
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• pp.205-211
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• 2005

국내의 연간 공사발주 물량의 약 $10\%$를 차지하고 있는 턴키공사는 발주처의 인력부족과 기술력부족으로 인하여 충분히 검토되지 못하고 진행되는 경우가 많으며, 발주자우위의 계약조항을 포함하고 있는 등의 문제점을 안고 진행되고 있다. 본 논문은 턴키공사가 가지고 있는 문제점으로 인하여 발생하게 될 클레임의 효과적인 예방을 위하여 현장에서 실제로 발생하고있는 클레임요인을 추출하고 영향도를 분석하여 그 결과를 실무에서 사용할 수 있도록 하는데 목적이 있다. 추출된 요인들에 대해서 전문가들에게 설문조사를 실시하여 턴키프로젝트에 미치는 영향도가 높은 클레임요인을 선별하고, 사례분석을 통한 클레임 금액의 조사를 실시하여 어떤 요인들이 클레임에 얼마나 영향을 미치는 지를 분석 검증하였다.

• 한국산업융합학회 논문집
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• 제22권5호
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• pp.529-536
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• 2019

Recently, various efforts have been tried in the construction industry to improve productivity by applying the fourth industrial revolution technology. Among the various technologies, researches for the automation and digitization of earthworks are being carried out steadily. As the interest in the benefits of digitalization of the earthwork field has increased, there have been more cases of technology development and application for digitalization of the earthwork field. However, there is not enough case study to present the analysis results of application cases. The purpose of this study is to verify the feasibility of applying the digitization technology of the earthwork in actual worksite. In order to digitize the worksite terrain, it is required the process of field measurement, measurement data registration, earthwork information input, and analysis cell generation. Particularly, it is possible to achieve information-enabled digitization rather than digitalizing only the shape through the input of the earthwork information and the analysis cell generation. By using the digital information of the earthwork field, it is possible to visually recognize the change of the earthwork field, so that it is expected to enhance the worker 's understanding and to be highly applicable to the management work. It is expected that the digital technology of earthwork site will be able to know the precise amount of volume change of the earthwork numerically, and it will be highly applicable to construction management.

• 한국기후변화학회지
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• 제9권1호
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• pp.47-58
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• 2018

In this study, we evaluated the uncertainty in the process of selecting GCM and downscaling method for assessing the impact of climate change, and influence of user-centered climate change information on reproducibility of Chungju Dam inflow was analyzed. First, we selected the top 16 GCMs through the evaluation of spatio-temporal reproducibility of 29 raw GCMs using 30-year average of 10-day precipitation without any bias-correction. The climate extreme indices including annual total precipitation and annual maximum 1-day precipitation were selected as the relevant indices to the dam inflow. The Simple Quantile Mapping (SQM) downscaling method was selected through the evaluation of reproducibility of selected indices and spatial correlation among weather stations. SWAT simulation results for the past 30 years period by considering limitations in weather input showed the satisfactory results with monthly model efficiency of 0.92. The error in average dam inflow according to selection of GCMs and downscaling method showed the bests result when 16 GCMs selected raw GCM analysi were used. It was found that selection of downscaling method rather than selection of GCM is more is important in overall uncertainties. The average inflow for the future period increased in all RCP scenarios as time goes on from near-future to far-future periods. Also, it was predicted that the inflow volume will be higher in the RCP 8.5 scenario than in the RCP 4.5 scenario in all future periods. Maximum daily inflow, which is important for flood control, showed a high changing rate more than twice as much as the average inflow amount. It is also important to understand the seasonal fluctuation of the inflow for the dam management purpose. Both average inflow and maximum inflow showed a tendency to increase mainly in July and August during near-future period while average and maximum inflows increased through the whole period of months in both mid-future and far-future periods.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.667-694
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• 2015

The suspended dome system is a new structural form that has become popular in the construction of long-span roof structures. Suspended dome is a kind of new pre-stressed space grid structure that has complex mechanical characteristics. In this paper, an optimum topology design algorithm is performed using the enhanced colliding bodies optimization (ECBO) method. The length of the strut, the cable initial strain, the cross-sectional area of the cables and the cross-sectional size of steel elements are adopted as design variables and the minimum volume of each dome is taken as the objective function. The topology optimization on lamella dome is performed by considering the type of the joint connections to determine the optimum number of rings, the optimum number of joints in each ring, the optimum height of crown and tubular sections of these domes. A simple procedure is provided to determine the configuration of the dome. This procedure includes calculating the joint coordinates and steel elements and cables constructions. The design constraints are implemented according to the provision of LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Constitution). This paper explores the efficiency of lamella dome with pin-joint and rigid-joint connections and compares them to investigate the performance of these domes under wind (according to the ASCE 7-05), dead and snow loading conditions. Then, a suspended dome with pin-joint single-layer reticulated shell and a suspended dome with rigid-joint single-layer reticulated shell are discussed. Optimization is performed via ECBO algorithm to demonstrate the effectiveness and robustness of the ECBO in creating optimal design for suspended domes.