• Journal of the Korean Geotechnical Society
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• v.30 no.6
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• pp.23-39
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• 2014

An artificial rainwater reservoir installed in urban areas for recycling rainwater is an eco-friendly facility for reducing storm water effluence. However, in order to recycle the rainwater directly, the artificial rainwater reservoir requires an auxiliary system that can remove non-point source pollutants included in the initial rainfall of urban area. Therefore, the conventional soil filtration technology is adopted to capture non-point source pollutants in an economical and efficient way in the purification system of artificial rainwater reservoirs. In order to satisfy such a demand, clogging characteristics of the sand filter layers with different grain-size distributions were studied with real non-point source pollutants. For this, a series of lab-scale chamber tests were conducted to make a prediction model for removal of non-point source pollutants, based on the clogging theory. The laboratory chamber experiments were carried out by permeating two types of artificially contaminated water through five different types of sand filter layers with different grain-size distributions. The two artificial contaminated waters were made by fine marine-clay particles and real non-point source pollutants collected from motorcar roads of Seoul, Korea. In the laboratory chamber experiments, the concentrations of the artificial contaminated water were measured in terms of TSS (Total Suspended Solids) and COD (Chemical Oxygen Demand) and compared with each other to evaluate the performance of sand filter layers. In addition, the accumulated weight of pollutant particles clogged in the sand filter layers was estimated. This paper suggests a prediction model for removal of non-point source pollutants with theoretical consideration of the physical characteristics such as the grain-size distribution and composition, and change in the hydraulic conductivity and porosity of sand filter layers. The lumped parameter ${\theta}$ related with the clogging property was estimated by comparing the accumulated weight of pollutant particles obtained from the laboratory chamber experiments and calculated from the prediction model based on the clogging theory. It is found that the lumped parameter ${\theta}$ has a significant influence on the amount of the pollutant particles clogged in the pores of sand filter layers. In conclusion, according to the clogging prediction model, a double-sand-filter layer consisting of two separate layers: the upper sand-filter layer with the effective particle size of 1.49 mm and the lower sand-filter layer with the effective particle size of 0.93 mm, is proposed as the optimum system for removing non-point source pollutants in the field-sized artificial rainwater reservoir.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.9-19
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• 2021

This paper deals with the reinforcement performance of acrylate for reinforcing the settled railway roadbed. Concrete tracks have the advantage of reducing track maintenance costs and high resistance to track destruction. However, roadbed settlement is occurring in some construction sections, and the safety of railways is a serious concern because of difficulties in maintenance. Currently, maintenance through the track restoration method is being carried out in Korea as a way of roadbed settlement in concrete tracks, but continuous re-settlement can occur because the roadbed itself cannot be reinforced, and there are very few cases of reinforcement of railway roadbeds and field application. So the development of reinforcement materials and construction methods to reinforce railway roadbeds is required. Therefore, in this paper, acrylate was selected as reinforcement material for railway roadbed, and the reinforcement performance of acrylate was analyzed through experiment. As a result, it was analyzed that the acrylate can penetrate into a permeability coefficient of 1×10^-4 cm/sec, and secure uniaxial compression strength of 0.5 MPa/30min or more and stiffness of 80 MPa or more.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.117-125
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• 2008

In the domestic construction industry field nowadays, the usage of deck plates is currently increasing due to the lack of construction workers and the rised in construction cost. However, using deck plates manufactured by thin zinc galvanization in underground structures is criticised because it can lead to increase in maintenance cost caused by rust generation and water leakage. As a solution for this particular problem, deck plates created by Lath and Mortar instead of zinc galvanized steel sheets were developed. This paper deals with the experimental study on flexural behavior of deck plate using metal lath and mortar. Seventeen fullscale specimens were constructed and tested with different type of truss, the diameter of the top and bottom bar, and the thickness of slab. Tests results show that LAMO deck displayed equal performance such as zinc galvanized steel sheets.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.132-140
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• 2019

In this study, a specimen composed of columns, walls, beams, and slabs was fabricated to investigate the estimated reliability using nondestructive test method for the location of structural members of reinforced concrete single layer structures. And for accurate analysis in the comparison process with the existing estimation formula, we try to analyze the reliability through statistical approach by using error rate comparison and Confidence interval estimation. As a result, The average error rate of the core test was 18.8% compared with the result of estimating the compressive strength using the ultrasonic pulse velocity method. The average error rate of the core test results compared with the result of estimating the compressive strength using the rebound hardness method was 20.1%, confirming the field applicability. it is judged that the reliability of the compressive strength estimation can be derived from the wall member to make a quick and efficient structure safety diagnosis using the ultrasonic pulse velocity method. In addition, it is judged that the reliability of the compressive strength estimation can be derived from the beam member to make a quick and efficient structure safety diagnosis using the rebound hardness method.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.507-515
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• 2017

This study is to develop a high quality lightweight foamed concrete that can be applied in the field using EXFG by cracking reducing agent combined with FGD and ALS. First, to increase the volume of foam, the flow and density of the mixture was increased and decreased, respectively. At this time, the effect of substitution ratio of EXFG on fluidity was negligible. The fraction of foam was the highest at EXFG 1%, and the settlement was found to be prevented by the expansion reaction at EXFG 1%. At this time, the ratio of foam was 65%. In the compressive strength, the strengths were similar or decreased when the substitution ratio of EXFG was more than 1%. The apparent density satisfied the KS 0.5 type at the bubble contents was 65%. In case of EXFG substitution, dry shrinkage was decreased by about 10%. As the substitution ratio of EXFG increased, the thermal conductivity increased proportionally.

• KCI Concrete Journal
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• v.13 no.2
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• pp.10-18
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• 2001

The spectral analysis of surface waves (SASW) method, which is an in-situ seismic technique, has mainly been developed and used for many years to determine the stiffness profile of layered media (such as asphalt concrete and layered soils) in an infinite half-space. This paper presents a modified experimental technique for nondestructive evaluation of in-place cement mortar compressive strength in single-layer concrete slabs of rather a finite thickness through a correlation to surface wave velocity. This correlation can be used in the quality control of early age cement mortar structures and in evaluating the integrity of structural members where the infinite half space condition is not met. In the proposed SASW field test, the surface of the structural members is subjected to an impact, using a 12 mm steel ball, to generate surface wave energy at various frequencies. Two accelerometer receivers detect the energy transmitted through the medium. By digitizing the analog receiver outputs, and recording the signals for spectral analysis, surface wave velocities can be identified. Modifications to the SASW method includes the reduction of boundary reflections as adopted on the surface waves before the point where the reflected compression waves reach the receivers. In this study, the correlation between the surface wave velocity and the compressive strength of cement mortar is developed using one 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slab of 2,000 psi (140 kgf/$\textrm{cm}^2$) and two 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slabs of 3,000 psi (210 kgf/$\textrm{cm}^2$).

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.123-131
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• 2015

The purpose of this study is to analysis the noise characteristics about noise type, sound level, and noise occurrence frequency of living noise in residential buildings. The field measurement was conducted to classify the types of living noise and to examine the actual states of noise occurrence for each living noise source. Among the 24 types of living noise, 10 noise sources were selected based on the loudness and frequency of each living noise. The result indicated that 10 noise sources show the difference on each noise occurrence characteristic by time zones. Therefore, to reduce noise, a management plan should be introduced based on the actual state of the noise occurrence, considering the individual noise source and the time slot during noise frequently occurs. Moreover, the noise standard for each noise types of living noise should be specificated and the education for residents about characteristics of living noise types should be conducted to improve the consciousness of residents.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.285-292
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• 2014

BIM (Building Information Modeling) is a new paradigm that includes construction life-cycle, and BIM has become mandatory regulation according to the Public Procurement Service since 2016, which accelerates its application. BIM is now expand from architectural field to infrastructure industry. Through pilot projects, BIM has been challenged with verification process. This trend has affected to maintenance and operation (M&O) phase of construction life-cycle. Advanced country has already published their research and result with feasibility study and guidelines. In this paper, we conduct the feasibility study to adopt BIM-based infrastructure management system. Bridges and tunnels were selected as application target, and benefit/cost ratio were used. The result shows that BIM-based infrastructure management system is feasible when the level of detail is more than "Medium" in bridge, and "High" in tunnel.

• Resources Recycling
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• v.22 no.1
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• pp.20-28
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• 2013

Recently, as the registration of vehicles increases, the utilization of the waste tires is emerging as environmental issues. Crumb rubber reproduced by scrap tires has been reused up to 25% in the construction field. The purpose of this paper is to investigate the mechanical properties of sulfur-rubber concrete (SRC) and to suggest the optimum mix design in terms of the compressive strength. Specimens were prepared with various mixing parameters: amount of sulfur, rubber, and micro-fillers. Two casting processes were also mentioned; dry process and wet process. The results mainly showed that the compressive strength of SRC decreased with an increment of rubber content. However, adding micro-filler and adjusting sulfur contents could improve the compressive strength of SRC. Optimum values of sulfur and rubber content were selected by workability and compressive strength of SRC. SRC can be applied to road constructions where high strength of concrete is not concerned, to wall panels that require low unit weight, to construction of median in highways to resist high impact load, and in sound barriers to absorb sound waves.

• Korean Institute of Interior Design Journal
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• no.13
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• pp.187-196
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• 1997

A Study on the Characteristics of the Modern Chair Design The features of the modern chair design results from the diverse life style unfolded as per the 20th century social structure and the change of the residential space, and new design has been being developed by the scientists and the artists in various fields through their cooperated work in a way. The field of the scientific or technical study and creation of arts can be developed where they can evoke the sympathy in the circumstances under which the various styles of both arts and science meet across, complement crash together, and grow up. The operation which can control in the network of such pluralistic sphere has been needed for a long period and it has been facing the needs from a time and society. The engineering furniture as the counterplan of the above has brought the value of materials into relief to the forms of human life by making the properties of matter the maximum value or changing it. It can be summarized as following characteristics in its materials and forms along as well as the 3 types (handycrafty, mechanical, and ecological expression) in process through the 20th century. 1. Characteristics in Materials elasticity of the chair as per the changes of the flexibility in the steel pipe development of systematic chair using the plasticity of the plywood, plastic, and wire lightweight due to the materials such as aluminum. 2. Formative characteristics formative simplicity for the increase of the function and the quality improvement such as sociality, productivity, environmental and aesthetic nature emphasis on the structure as per the architectural environment and tecniques pursuit of the forms as a container of the human body seeking for the formative values as the cultural symbols coping with the needs from thepluralistic social structure Furniture is not the makeup for convenience sake but most importantexpression as necessaries of our environments. It should identify itself always as per these kind of needs and also it should be able to used to keep the relation of such mutual division, otherwise the purchase of new furniture should be necessary according to every change of the existing situatiov. Our residence doesn't need the specific style but expresses only the properties of the dwellers.