• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.676-682
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• 2016

In this study, rainwater-greywater hybrid system was installed and operated for 1 year in order to evaluate its water quantity, water quality, and economic efficiency in building no. 39. This system was expected to overcome each disadvantages of and maximize each advantages. Low-greywater that was washed up from shower room was treated by MBR (Membrane Bioreactor) and ozone oxidation. Rainwater that was collected from the rooftop was stored in a reservoir, and then transferred to the storage tank that was mixed with treated greywater. After 1 year operating in building no. 39, rainwater and greywater was used to supply $2,599m^3$ of toilet flushing water. In terms of water quality, rainwater was satisfied far the greywater reuse standards except for E.coli. Moreover, low greywater quality was acceptable except for E. coli, BOD, SS, and turbidity. In addition, economic analysis was obtained from benefit-cost ratio (B/C) with 1.11. It implies that the feasibility of the project was reasonable. Furthermore, various research and policy to improve the economic efficiency of water recycling facilities is required to expand the use of water recycling facilities.

• Journal of Korean Society of Transportation
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• v.21 no.5
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• pp.73-81
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• 2003

The Government presented improvement plans such as "Traffic Accident Frequent Point" and "Hazardous Roads" to reduce traffic accidents on the increase after 1980s. In case of the hazardous roads, they are expressed by grades which are marked by geometric elements such as width, radius, grade. sight distance. and other environmental factors. As each business for improving roads goes by only focusing on improvement of geometric elements, excessive expense can be invested too much nowadays causing economical waste. Therefore, as improvement plans approached by economic access are needed, this paper shows the cost-effective improvement of the business to keep safety related to traffic accident and economical waste. The hazardous roads which authorized by Gwang-ju National Road Preservation Office of Construction and Transportation Ministry in 1995 for business for improvement of roads, were investigated before 1999. First of all, estimating traffic accident models are presented by using existed data statistically. The models help to maximize traffic accident decrease through control of the presented factor. Secondly, optimum construction cost of improvement is presented to prevent overcapitalization. However, this paper is limited because it was difficult to sort the data with various areas and to approach various ways.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.215-225
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• 2011

In general, the precast columns can obtain its homogeneous quality as they are produced in a factory with a hollow concrete block type by using high strength concrete, so that they can generate the reduction of dead load. Such a method of precast hollow concrete columns is already implemented in USA and Japan and used for connecting between blocks which use PC tendons. However, it is inevitable to have uneconomical construction with excessive cost in early stage when PC tendons are used. This study aims to develop an economical precast column with high quality and constructability which consists of only splice sleeve and general reinforcing bar without using PC tendons in order to reduce the construction period and cost. To achieve this goal, this study tested the performance of total 5 minimized models in the experiment with the variables such as hollowness, diameter of main reinforcement bar and cross-sectional size for the cross section of precast column by using grouting type splice sleeve which is a new type joint rebar. And it also verified the performance of column in the experiment for a large-sized model in order to overview its applicability by excluding large scale effect.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.55-64
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• 2013

As GHG target management is introduced in Korea, designated establishment takes responsibilities to reduce more than 30% of expected GHG emission until 2020. Although decreasing GHG has been requested to universities which consume great amount of energy, there are difficulties to apply high cost countermeasures. Therefore, this research suggest a low cost, easily-applicable energy saving method, and derive potential GHG reduction amount in the case of SNU, Kwan-ak campus. First of all, 11 rooms of different use were chosen as the samples, and energy consumption in each room was measured. Standard models for each room were built through researching on the electric devices in each room. Moreover, energy consumption was computed for each devices through analyzing the pattern of electricity consumption. 32 GHG reduction technology and action program were chosen, and they were applied to the standard models for individual rooms. Through multiplying energy reduction rate of each program to energy consumption of each electric device, maximum energy reduction of each electric device is derived. Through that, Maximum GHG reduction for individual rooms and each month and the total GHG reduction capacity of Kwan-ak campus were computed. It was found out that approximately $5,311tCO_2$-eq can be reduced, when reduction technology and action program suggested by this research are applied. It appeared 24.48% of requested reduction amount to SNU can be reduced, till 2016.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.220-227
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• 2015

Ultra high performance concrete (UHPC) uses large quantities of steel fiber, silica fume, filler and superplasticizer for a low water-to-binder ratio (W/B). Despite of exceptional mechanical performances, UHPC exhibits increased viscosity due to the adoption of silica fume and its fabrication cost is costlier than ordinary concrete because of the use of large quantities of expensive materials. Following, this study evaluates the mechanical properties of 180MPa-UHPC using zirconium silica fume (Zr) instead of silica fume with respect to the quantity and type of superplasticizer (SP) and the size of filler. The results reveal that the Zr-UHPC using W/B of 20%, 100% of Zr, amount of SP-L of 2 to 3% and $4{\mu}m$-filler with steel fiber in 1.5 vol.% can develop better fluidity than the traditional mix composition using silica fume and secure a compressive strength higher than 180 MPa. In addition, the proposed mix composition is shown to enable a reduction of the fabrication cost by 33% compared to traditional UHPC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.67-74
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• 2021

Domestically, technical condition evaluation for breakwaters has been conducted through safety checks and safety diagnosis. If necessary, maintenance for the facility is conducted. However, in recent years, the need for infrastructure management has been increasing from a life-cycle-cost perspective. For these reasons, the "Sustainable Infrastructure Management Basic Act" was enacted. Previously, only the technical part of the breakwaters was evaluated. However, based on the act, comprehensive management of breakwaters will be possible through performance improvement by adding economic and political evaluations. In this study, evaluation factors and evaluation methods were developed for a breakwater rehabilitation project. The purpose of this study is to present a development direction, items, and methods for the evaluation of breakwater performance improvement to be applied in future practice. This study reviews the concept of maintenance and performance improvement, the literature related to performance improvement, and the project type for the common standard of performance improvement. Evaluation items and evaluation methods for breakwater rehabilitation are suggested to be reviewed by experts. The methodology suggested in this study could be used for preventive maintenance and to reduce accidents.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.89-99
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• 2006

The PCRW (Precast Concrete Retaining Wall) has many advantages compared with cast in place concrete retaining wall : shorter construction period, excellency of quality and minimum interference with the adjacent structure and traffics. However, shallow foundation type of PCRW, which has comparatively better ground condition, has some disadvantages such as difficulty in transportation and higher cost due to the size of PCRW being expanded by resisting only with self-weight if there is no other supplementary reinforcement. The presented study, in order to complement such disadvantages of PCRW, have applied the micropile method. The micropile method has advantages like low-cost and high-efficiency and does not require huge space, because it can be executed with small size equipment. However, the mechanical behavior characteristics of the PCRW reinforced by micropile, which is installed to improve the reinforcement effect, is not yet clearly identified and there is no suggested standard as to the length, diameter, install angle and install position of micropiles. Hence, this method is yet being designed depend on engineer's experience. In this study, various laboratory model tests as to sliding and overturning were performed in order to identify and present the optimum type of reinforcement and reinforcement effect of the PCRW reinforced by micropiles. In addition, it also executed numerical analysis for the purpose of verifying the optimum type of reinforcement for micropiles based on the results of laboratory model tests. The optimum reinforcement type of micropiles was estimated by model test and numerical analysis. The length of micropiles is 0.4 times wall height and the diameter is 0.04 times wall length.

• Journal of Cadastre & Land InformatiX
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• v.53 no.2
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• pp.53-66
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• 2023

Recently, there has been a significant interest in the development of autonomous driving simulation environment based on digital twin. In the development of such digital twin-based simulation environment, many researches has been conducted not only performance and functionality validation of autonomous driving, but also generation of virtual training data for deep learning. However, such digital twin-based autonomous driving simulation system has the problem of requiring a significant amount of time and cost for the system development and the data construction. Therefore, in this research, we aim to propose a method for rapidly designing and implementing a digital twin-based autonomous driving simulation system, using only the existing 3D models and high-definition map. Specifically, we propose a method for integrating 3D model of FBX and NGII HD Map for the Busan EDC area into CARLA, and a method for adding and modifying CARLA functions. The results of this research show that it is possible to rapidly design and implement the simulation system at a low cost by using the existing 3D models and NGII HD map. Also, the results show that our system can support various functions such as simulation scenario configuration, user-defined driving, and real-time simulation of traffic light states. We expect that usability of the system will be significantly improved when it is applied to broader geographical area in the future.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.3
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• pp.33-42
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• 2005

The bearing methods using pile of steel itself or reinforced concrete has been applying which in excavated depth was not deep. Also, the retaining wall as resisting structure to lateral force has taken weakness that the cure periods of concreted is long. Recently, with the material cost of steel, the application of cement is more increasing trend. In this study, the design methods of earth retaining and retention wall within the pre-casted concrete pile, PHC(Pretentioned spun High strength Concrete piles), was proposed which in the ground condition of excavated depth was not deep. The typical ground conditions, cohesive and non-cohesive soil, was considered as follows; soil strength as internal friction angle and UU(Undrained Unconsolidation triaxial test) strength, soil reaction and stabilization of structures. The application of design methods could be confirmed through the comparing and analyzing between measured data and utility software for the design.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.157-162
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• 2004

Constructed wetlands are considered as an important tool for wastewater treatment, wastewater management and flooding control. In addition, one of the most promising technologies for application in many countries seems to be constructed wetlands, due to their properties such as utilization of natural processes, simple construction, operation and maintenance, process stability, cost effectiveness, etc. This study considered possibility of treatment of livestock wastewater using a constructed wetland. The removal efficiencies of $COD_{cr}$, TOC, TN, TP, SS, and color were 97.6%, 96.6%, 97.0%, 96.7%, 99.0%, and 85.6%, respectively. In particular, SS was completely removed. However, $Cl^{-}$ concentration of the constructed wetland effluent was higher than that in influent. In conclusion, constructed wetlands could be applied to livestock wastewater treatment if $Cl^{-}$ would be properly treated. Further, it needs time for stabilization to reduce the pollutants which were accumulated in soil.