• Resources Recycling
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• v.20 no.5
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• pp.58-63
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• 2011

pH control-precipitation method is used for recovery of EDTA from waste fluid of archeological waterlogged wood conservation treatment. EDTA has been used for eliminating of blacken effect in archeological waterlogged wood which was buried in the ground for long period of time. The black substance is generated by Fe$^{3+}$ in the soil reacted with tannin in the archeological waterlogged wood. In order to remove the black substance in archeological waterlogged wood, EDTA was used. The black substance is eliminated from wood as Fe-EDTA complex are formed, and EDTA is separated and precipitated from Fe-EDTA complexes at pH 2.68 or less. The result of analysis of the precipitated products and the commercial EDTA by FT-IR and FE-SEM showed that precipitated product by pH adjusted was not a type of Fe-EDTA complex, but pure EDTA. In this study, Fe$^{3+}$ from waste fluid of EDTA can be separated by HCl added. EDTA can be recycled by using the method of precipitation of EDTA in a strong acid.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.70-79
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• 2020

The main objective of this research to develop an IoT based wireless contactless ultrasonic system (ICUS) and its application to concrete structure. The developed system consists of 16 mems, 2Mhz digitizer, amplifying circuit, FPGA, and wifi module, enabling to measure leaky surface waves from concrete specimens without physical coupling process and wires. Multi-channel analysis is performed to improve the accuracy of data analysis, and the velocity of leaky surface waves and acoustics are derived. Field inspection of railroad concrete sleepers is conducted to evaluate the performance of the system and to compare the results with conventional ultrasonic pulse velocity (UPV). As a result of the field inspection, UPV was limited to evaluate damages. This is because crack pattern of railroad sleepers is parallel to ultrasonic ray path and accessibility of the railroad at the field is disadvantageous to contact-based UPV. On the other hand, ICUS possibly detect the damages as reduction of dynamic modulus by up to 59% compared to non-damaged specimen.

• The Journal of the Convergence on Culture Technology
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• v.4 no.4
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• pp.413-418
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• 2018

The purpose of this study is to investigate the cause of rail corrugation and the track force for concrete track (STEDEF) in the urban transit. From the field measurements, the dynamic wheel load, vertical displacement of sleeper and rail bending stress were measured and it was evaluated by regarding to the rail corrugation. As a result of the study, the causes of rail corrugation was experimentally proved by frequency analysis using measured dynamic wheel load data. The influence of corrugation on dynamic wheel load, rail bending stress and sleeper displacement was evaluated that the periodic irregularities of rail corrugation on the rail surface amplified the dynamic track force such as the dynamic wheel load, and thus the rail bending stress and the vertical displacement of sleeper could be increased by a maximum of 1.7 times.

• The Journal of the Convergence on Culture Technology
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• v.5 no.1
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• pp.389-394
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• 2019

In case of damaged timber sleepers, maintenance is carried out according to the track inspection standard. However, it is difficult to detect the extent of damage on the bridge, and maintenance is depended on inspector's judgment. In this study, we propose to improve the evaluation criterion of timber sleepers for the ballast-less tracks on serviced urban railway bridge. The timber sleepers on railway bridge was classified according to degree of damage, and damage scores were calculated for each damage grade. Also we have improved the maintenance system of the timber sleepers through the history management system of the individual timber sleepers on railway bridge. As a results, it was judged that systematic management of timber sleepers could be possible during maintenance.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.108-115
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• 2012

Archaeological waterlogged woods found under the sea, in lakes, or in swamp environments are generally weak and fragile. If waterlogged wood materials were taken out of the water and left without modification, they would collapse and lose their original dimensions completely. Conservation is performed to replace the water with chemical agents and to give dimensional stabilization and durability. EDTA and PEG are the most commonly used in the preservation of wood. pH control-precipitation method is used for recovery of EDTA from waste fluid of archeological waterlogged wood conservation treatment. The black substance is eliminated from wood as Fe-EDTA complex are formed and EDTA is separated and precipitated from Fe-EDTA complexes at pH 2.68 or less. The result of analysis of the precipitated products and the commercial EDTA by FT-IR and FE-SEM showed that precipitated product by pH adjusted was not a type of Fe-EDTA complex, but pure EDTA. Waste fluid produced in PEG treatment shows the black color and has an offensive odor by organic matter extracted from wood. Color of waste fluid is decolored with oxidation reaction by peroxy hydrate. In FT-IR and SEM-EDX of PEG after freeze-drying process, no significant change of functional groups induced from oxidation is observed, and any metal ion does not exist in the solid PEG specimen. The molecular weight of PEG is measured using GPC and viscometry. Properties of PEG before and after preservation treatment, and after oxidation with $H_2O_2$ were not changed. Consequently, the peroxidation with $H_2O_2$ is a reasonable and simple method to decolor the used PEG solution.

• Journal of Conservation Science
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• v.37 no.5
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• pp.579-589
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• 2021

Five waterlogged wood artefacts were excavated from Suyeong-ri site in Hwaseong, South Korea. The aim of the present study was to identify the species and estimate the date of manufacture and the manufacturing method of these artefacts. The study also aimed to conserve the original shapes of waterlogged wood artefacts by using the vacuum freeze drying method. The two large waterlogged woods were identified as Ulmus spp. and Morus spp., whereas one of the three small waterlogged woods was identified as Abies spp. and the other two as hard pine. Radiocarbon dating using wiggle match dated the manufacturing of these wooden artefacts between BCE 8520-8490 or BCE 8470-8290 in the Neolithic age, and a similar period was also confirmed for seed excavated from a place close to the location where the waterlogged wood artefacts were excavated. The surface of waterlogged wood artefacts had several traces of manufacturing processes - traces of tearing and chopping - were observed. Based on these observations, it was confirmed that stone adz was used to make these wooden artefacts. Thereafter, the waterlogged wood samples were conserved by immersing them into PEG#4,000 of concentration in water from 10% to 40% at room temperature(15~25℃) and subjecting them to vacuum freeze drying. However, the internal moisture was not completely removed in some thick parts of waterlogged woods by applying the general schedule such as raising the shelf temperature as the surface temperature rises. Therefore, additional study is required using the schedule-method for vacuum freeze drying of large waterlogged wood.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.260-266
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• 2023

In recent years, excessive emissions of carbon dioxide(CO₂) have become the cause of global climate change. Consequently, there has been significant research activity aimed at both removing and utilizing CO₂. This study assesses the potential utilization of railway tie concrete waste, generated from railway infrastructure, as a CO₂ absorption material and investigates the physicochemical properties before and after CO₂ absorption to understand the CO₂ removal mechanisms. Railway tie concrete waste primarily consists of Si(26.60 %) and contains 9.82 % of Ca. Compared to samples of Cement and Normal concrete waste, it demonstrated superior potential for use as a CO₂ absorption material, with approximately 98 % of the Ca content participating in CO₂ absorption reactions. Through Thermogravimetric Analysis(TGA) and X-ray Diffraction(XRD) analysis, it was confirmed that the carbonate reaction, where the Ca in railway tie concrete waste converts into CaCO₃ through reaction with CO₂ gas, is the primary mechanism for CO₂ removal. Furthermore, Scanning Electron Microscopy(SEM) analysis revealed the formation of numerous CaCO₃ particles with sizes less than 0.1 ㎛ after the CO₂ absorption reaction. This transformation of large internal voids in the CO₂ absorption material into mesopores resulted in an increase in the specific surface area of the material.

• Journal of the Korean Society for Railway
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• v.5 no.3
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• pp.10-14
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• 2002

2 열의 레일을 침목에 일정한 간격으로 고정한다고 하는 궤도의 구조는 철도의 발상 직후부터 현재에 이르기까지 기본적으로 변하지 않고 있다. 궤도는 옥외에 건설되는 장대한 선형 모양의 구조물이며 자연의 영향을 항상 받아 때로는 재해를 받아 파손되는 것도 피할 수 없는 점에서 취약하게 보이지만, 극히 유연성이 높은 궤도구조가 채용되어왔다고 하는 사정이 있다. 그러나, 대형화, 고속화, 고밀도화 등 차량의 운전 성능 향상에 따라 궤도는 그 기능을 점차 향상시켜 왔다. (중략)

• Proceedings of the KSR Conference
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• 2006.05b
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• pp.688-695
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• 2006

• Magazine of RCR
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• v.16 no.1
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• pp.12-16
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• 2021