• Journal of the Korean GEO-environmental Society
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• 제20권5호
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• pp.23-29
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• 2019

In general, pipe laying works are performed by constructing underground facilities such as pipes and then refilling the rest of the area with sand or soil. However, there are many problems in the compaction process such as difficulties in tampering around the underground facility and low compaction efficiency. Such problems cause deformation and damage to the underground pipes during refilling work and ultimately cause road sinks. Construction methods using CLSM are one of the typical methods to solve these issues, and recently, studies on CLSM using coal ash, which has similar engineering properties as sand, have been actively performed to protect environment and recycle resources. While many studies have been conducted to recycle fly ash in many ways, the demand for recycling bottom ash is increasing as most of the bottom ash is not recycled and reclaimed at ash disposal sites. Therefore, in order to find bottom ash applications using eco-friendly soil binders that are environmentally beneficial and conform with CLSM standards, this study investigated flow characteristics and strength change characteristics of eco-friendly soil binders, weathered granite soil, a typical site-generated soil, bottom ash, and fly ash mixed soil and evaluated the soil pollution to present CLSM application methods using bottom ash.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제20권2호
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• pp.741-749
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• 2019

A hydraulic breaker attached to an excavator is a kind of constructuion equipment which is used for the disassembling of buildings, crashing road pavement, breaking rocks at quarry and etc. Therefore, the performance of the hydraulic breaker is mainly evaluated by the impact quantity and impact efficiency, which is an important factor for both the manufacturer and the user. In this paper, modeling and simulation for the prediction of the impact of the hydraulic breaker was conducted according to hydraulic pressure area and operating conditions of the hydraulic valve and piston using the commercial tools SimulationX for the 20ton hydraulic breaker which is mainly used in construction site. In order to verify the reliability of modeling and simulation, the results of previous experimental studies were compared and verified. The results of this study are expected to be useful for predicting the impact of the hydraulic breaker at the design stage before manufacturing and for studying parameters for improving the impact quantity. In addition, the manufacturer predicts that the development time and cost will be reduced through trial and error prevention by predicting the impact of the hydraulic breaker through the results of this paper.

• Korean Journal of Heritage: History & Science
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• 제47권3호
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• pp.108-127
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• 2014

Gangwha was a capital city of Goryeo, in spite of short-term occupation, where various national facilities such as palace stood in a row. Nevertheless, its historic importance has been undervalued owing to undiscovered palace. According to ${\ll}Goryeosa{\gg}$, palace in Gangwha was built in imitation of that of Gaegyeong. If it is true, the site of the old palace in Gaeseong as an original could give significant information for that of Gangwha. The distinct feature of Gaegyeong is that the palace was located in the west area of the centerline from north to south and pond lay in the east side. There is a mountain in the center of capital and two rivers runs along side the mountain. Gunggol at Gwancheong-ri is a best place where structural peculiarities of Gaegyeong can be applicable to Gangwha. There is an area of celadon distribution and is some topographic similarities such as central mountain, two rivers are quite similar. It is assumable that excavation result of no. 405 Gwancheongri reflects the function of east pond and thoroughfare responds to main street from north to south of Gaegyeong. After all the analysis from archaeological information, old maps, cadastral maps, topographic similarities and so on, Gunggol at Gwancheong-ri within an arc shape road is a most suitable place as palace in Gangwha.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제20권5호
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• pp.502-509
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• 2019

Studies have been made on performance evaluation of expansion joint systems for an ordinary highway or road bridge. However little study has been made for runway connection bridges at airports. A study on performance evaluated from computer code analysis and shrinkage, extension, and compression repetition tests based on KS F 4425 is conducted to a newly developed expansion joint system which has been installed in a runway connection bridge at Incheon Airport Extension 2 Construction Site. The MIDAS computer code is used to analyze the performance before the manufacture of the mock-up of expansion joint system on the basis of design requirements. Tests based on the KS F 4425 of 2001 year-version are conducted for the mock-up. Domestic codes and standards to validate the performance of the expansion joint system in a connection bridge have been developed for a vehicle. However the expansion joint system tested in this study is installed in a runway connection bridge for an aircraft. Conservatively the heaviest one among airplanes departing and landing at Incheon Airport is assumed level-F $468.4kN/m^2$ and adopted for the tests and analyses in this study. KS F 4425 method is selected for the shrinkage, extension, and compression repetition tests. No remarkable problem was observed for the 2,500-cycle shrinkage and extension and two million-cycle repeatition load tests. The results of this study are expected to contribute to establishment of code and standard for the performance validation of an expansion joint system installed in a runway connection bridge for an aircraft by providing performance test results and computer analysis results based on finite element methods.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제32권6호
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• pp.481-495
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• 2020

After the resonator on the basis of the wave-filter theory was designed to control the waves with a specific frequency range surging into the harbor, the several case with the use of resonator have been reported in some part of sea, including the port of Long Beach, USA, and yacht harbor at Rome, Italy in order to control the long-period wave motion from the vessels. Recently, the utility and applicability of the resonator has been sufficiently verified in respect of the control of tsunami approximated as the solitary wave and/or the super long-period waves. However, the case with the application of tsunami in the real sea have not been reported yet. In this research, the respective case with the use of existing resonator at the port of Mukho and Imwon located in the eastern coast of South Korea were studied by using the numerical analysis through the COMCOT model adapting the reduction rate of 1983 Central East Sea tsunami and 1993 Hokkaido Southwest off tsunami. Consequently, the effectiveness of resonator against tsunami in the real sea was confirmed through the reduction rate of maximum 40~50% at the port of Mukho, and maximum 21% at the port of Imwom, respectively. In addition, it was concluded that it is necessary to study about the various case with application of different shape, arrangement, and size of resonator in order to design the optimal resonator considering the site condition.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제32권6호
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• pp.496-505
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• 2020

In the previous research, the effectiveness of resonator was confirmed through the numerical analysis on two cases with the use of existing resonator at the Mukho and Imwon ports located in the eastern coast of South Korea by discussing the reduction rates of 1983 Central East Sea tsunami, and 1993 Hokkaido Southwest off tsunami, respectively. In this study, the reduction rates of tsunami height with three different resonators, Type I, II-1, and II-2, at the Samcheok port were examined respectively through the numerical analysis using COMCOT model under the same condition as the previous study. It was discussed the spatial distribution of maximum height of tsunami, change of water level, and effectiveness of resonator with the presence of new types of resonator, and change of their sizes. As a result, the effectiveness of resonator was verified through the application of new types of resonator reducing about maximum 40% of tsunami height. In order to design the optimal resonator for the variety of site condition, it is necessary to research about the various cases applying different shape, arrangement, and size of resonator as further study.

• Journal of Wetlands Research
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• 제24권4호
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• pp.320-330
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• 2022

The Hangang river estuary, which is a natural estuary without structures such as estuary barrage, is an ecological pathway connecting the sea and rivers. Accordingly, Hangang river estuary has various species, and there is very valuable. Sediment classification in Hangang river estuary is three-dimensionally and diversely is distributed. Sediment classification in Hangang river estuary is also sensitively changed according to various factors such as climate change and river development. It is typically cause to landform and to develop a compound cross section. In Janghang wetland, the plant success is remarkable according to the morphological change at river bed. The purpose of this study is to identify the mechanism of wetland formation based on the observation on-site. As a result of the observation, Janghang wetland where was artificially created, has been grown according to the river bed change based on the flow rate and the plant success. The viscous surface layer material(fine grains of wash rod properties), which is not the main material(sand) of the river bed, but sub-materials of river bed, jas been settled on the pioneer plants(bolboschoenus planiculmis, etc.). It is an important role in the growth of a compound cross section and a wetland. After the wetland developed to the compound cross section, it is observed that the pioneer plants are transferred to other plant species.

• Journal of Wetlands Research
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• 제23권1호
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• pp.85-93
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• 2021

Sewage separation which often involves installing a new pipe to separate wastewater flow from stormwater runoff flow can be costly and depends highly on its feasibility in a site. To be able to develop a potentially more economical alternative that can also lessen major road traffic disturbance during this process, a different approach where a smaller sewage separator pipe is installed inside an existing combined sewer pipe was investigated. A small-scale of a box sewer and the proposed sewage separator pipe was constructed in the laboratory to observe and compare the deposition of solids and other solid-associated major pollutants at different flow rates. In addition, three-dimensional flow simulations considering five different scenarios were conducted using Ansys Fluent to observe the effect of the proposed sewage separator pipe to the hydraulic flow if installed inside the combined sewer pipe. Results revealed that the deposition of TSS, TCOD, TN, and TP were reduced by at least 60% when the wastewater was conveyed by the sewage separator pipe instead of the combined sewer pipe. Moreover, the flow simulations conducted showed that there was little to no major disturbance in hydraulic flow and velocity distribution when the sewage separator was installed inside a straight pipe and even at pipe transitions such as intersections, turns, and drop in elevation. Considering the pipe dimensions and the results of the study, the proposed approach can be promising in terms of reduction in pollutant deposition without a major effect on the hydraulic flow. Further investigation and cost-analysis should be done in the future to support these preliminary findings and help alleviate the problems caused by combined sewer overflows by introducing an alternative approach.

• Journal of the Society of Disaster Information
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• 제16권4호
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• pp.650-657
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• 2020

Purpose: In this study, the effectiveness of pilot project of PLSP (Priority Lane and Signal Preference) system, which was operated in Cheongju City, was analyzed. Method: The priority signal was operated by a police officer switching to a blue signal when approaching a fire truck through CCTV, and the priority lane of emergency vehicles was displayed on the road to enable preferential traffic. VISSIM simulation analysis was performed for the 1.2km section (3.8km) of the pilot project section and vehicle data was analyzed for some of the test operation sections. Result: Simulation analysis shows that the moving speed of the emergency vehicle can be increased by 42 km/h with the introduction of PLSP, which can be increased by approximately twice the speed. Travel time was reduced by about 3 minutes, and considerable improvements of 69% compared to cities that are not operating was analyzed. The pilot operation of Cheongju City showed a time-shortening effect of about two minutes on average, with the average time reaching 4 minutes and 14 seconds in the first period and the average time reaching 5 minutes and 40 seconds in the second period. Conclusion: The system has been shown to be effective in minimizing time-to-site arrival of emergency vehicles.

• Journal of Environmental Impact Assessment
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• 제31권6호
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• pp.359-368
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• 2022

It is essential to increase the implementation rate in order to increase the effectiveness of mitigation measures that can mitigate the negative impact of development projects. In the case of Environmental Impact Assessment (EIA),research on the implementation evaluation of development projects is insufficient, even though the effectiveness of mitigation measures has been steadily raised. Therefore, this study evaluated the implementation rate of the mitigation measures and identified the cause of the difference in the implementation rate for each mitigation measures in order to understand the current status of the ecological mitigation measures. The implementation rate of urban and road development projects mitigation measures was 56.0% and 64.4%, respectively. the implementation rate of 'Monitoring' mitigation measures was the highest in all development project. But, 'Habitat creation' and 'Accident prevention measures' were low. In addition, it was found that the implementation rate of the mitigation measures were high when the contents of the mitigation measure described in the report were specific. Through this study, it was found that in order to increase the implementation rate of the EIA ecological environment animal mitigation measures, it is necessary to reflect the environmental and geographical characteristics of the target site in detail. Furthermore, it is judged that this study can be used as a basic basis for enhancing the effectiveness of the EIA system introduced to mitigate the negative impact on the environment.