• Computers and Concrete
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• v.32 no.2
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• Fire Science and Engineering
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• v.26 no.6
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• pp.99-108
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• 2012

These days, spontaneous ignition phenomena by oxidizing heat frequently occur in the circumstances of processing and storing waste tires. Therefore, to examine the phenomena, in this work, this researcher conducted the tests of fires of fragmented waste tires (shredded tire), closely investigated components of the fire residual materials collected in the processing and storing place, and analyzed the temperature of the starting of the ignition, weight loss, and heat of reaction. For the study, this researcher conducted fire tests with fragmented waste tires in the range of 2.5 mm to 15 mm, whose heat could be easily accumulated, and performed heat analysis through DSC and TGA, DTA, DTG, and GC/MS to give scientific probability to the possibility of spontaneous ignition. According to the tests, at the 48-hour storage, rapid increase in temperature ($178^{\circ}C$), Graphite phenomenon, smoking were observed. And the result from the DTA and DTG analysis showed that at $166.15^{\circ}C$, the minimum weight loss occurred. And, the result from the test on the waste tire analysis material 1 (Unburnt) through DSC and TGA analysis revealed that at $180^{\circ}C$ or so, thermal decomposition started. As a result, the starting temperature of ignition was considered to be $160^{\circ}C$ to $180^{\circ}C$. And, at $305^{\circ}C$, 10 % of the initial weight of the material reduced, and at $416.12^{\circ}C$, 50 % of the intial weight of the material decreased. The result from the test on oxidation and self-reaction through GC/MS and DSC analysis presented that oxidized components like 1,3 cyclopentnadiene were detected a lot. But according to the result from the heat analysis test on standard materials and fragmented waste tires, their heat value was lower than the basis value so that self-reaction was not found. Therefore, to prevent spontaneous ignition by oxidizing heat of waste tires, it is necessary to convert the conventional process into Cryogenic Process that has no or few heat accumulation at the time of fragmentation. And the current storing method in which broken and fragmented materials are stored into large burlap bags (500 kg) should be changed to the method in which they are stored into small burlap bags in order to prevent heat accumulation.

• Journal of the Korean GEO-environmental Society
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• v.9 no.6
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• pp.5-12
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• 2008

In this research, the plate load tests on sand which is reinforced by Tirecell mat were simulated by finite element method (FEM). Tirecell mat made by waste tires has the same function and similar shape to Geocell for soil reinforcement and it can also be used for civil engineering structure. The results were compared with those of field plate load tests for evaluation of suitability of modeling method. From the comparison of both results, it can be seen that the settlements by FEM were very similar to test results with small margin under the ultimate bearing capacity. For the ultimate bearing capacities of two results, difference was very small. After the confirmation of the modelling, reinforcing effects with variation of cover depth and number of reinforcement layers by Tirecell were analyzed additionally. Reinforcing effect decreases with increasing soil cover depth, and this is similar to previous test results by soil cover depth. As the number of reinforcing layers increased, reinforcing effect increased. However at more than 2 reinforcing layers, reinforcing effect was negligible. In conclusion, the modeling method in this research might be used for analysis of reinforced structures using Tirecell mat.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.189-195
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• 2008

We developed emission factors for alternative fuels used in cement industries in Korea and also estimated reduction in emissions of greenhouse gas (GHG) by the use of alternative fuels. Emission factors for GHG of waste tire, waste plastic, waste oil and RDF were estimated to be about 89, 78, 77 and 95 ton $CO_2$/TJ respectively. When compared with previous studies, most of the results showed similar trends. The calorific value estimation and elemental analysis for energy source were implemented in order to estimate the exact emission factors and the reduction of GHG emissions using alternative fuel. In the case of 'A' company, $CO_2$ emission from alternative fuels was about 4% lower than that of bituminous coal only. Also in case of company 'B', $CO_2$ emission from alternative fuels was about 1.4% lower than that of only bituminous coal. In Germany and Japan, alternative fuel is not regarded to be fuel consumption in cement industry. When applying this rule, the emission reductions were about 4.3% for company 'A' and 6.3% for company 'B'. The results of this study may be considered as a useful information for developing strategies in reducing GHG emissions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.203-206
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• 2006

본 논문에서는 폐타이어를 지반보강재로 재활용하는 경우 배수조건에 따른 용출특성을 알아보기 위하여 실내실험을 실시하였다 배수조건과 비배수조건으로 연속식 용출시험을 수행하여. 유출수의 pH, 탁도, TOC, Zn 농도를 분석하였다. 실험결과 배수조건인 경우 시간이 경과할수록 용출 농도가 감소하여 주변 환경에 큰 영향을 미치지 않을 것으로 판단되나, 비배수 조건인 경우 용출 농도가 증가하는 현상을 발견할 수 있었다. 배수조건은 폐타이어가 지하수위 위에 존재하는 경우이며, 비배수조건은 폐타이어가 지하수위 아래에 존재하는 경우에 해당한다. 특히, 폐타이어가 지하수위 아래에 위치하는 경우 지오텍스타일의 클로깅 등으로 인하여 배수가 원활히 되지 않을 경우에는 주변환경에 큰 영향을 미칠 것으로 예상되며 이에 대한 각별한 주의가 필요할 것이다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1993.11a
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• pp.92-95
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• 1993

실험실 규모의 유동층 반응기(0.8 m H $\times$ 0.08 m I.D.) 에서 반응온도(700 -80$0^{\circ}C$), 유동화속도(1.5 - 3 Umf)의 영향에 따른 생성물의 수율, 생성가스의 조성, 생성가스의 발열량의 변화를 질소 분위기하에서 조사하였다. 반응온도를 700 에서 850 $^{\circ}C$로 증가시킬 때 촤의 수율은 36% 정도로 온도에 따라 큰 차이를 보이지 않은 반면 가스의 수율은 온도가 증가함에 따라 22 %에서 800 $^{\circ}C$까지 30%가량 증가하다 그 이상의 온도에서는 증가하지 않았다. 또한 수소와 메탄은 온도가 증가함에 따라 그 생성량이 증가하는 반면 에탄과 프로펜은 감소하였으며 단위 부피당 가스의 발열량은 감소하였다.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.266-268
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• 2011

본 논문은 폐타이어 열분해 잔류물인 char를 이용하여 수증기 활성화법으로 활성탄을 제조하였다. 활성화 온도가 증가할수록 비표면적은 증가하였으나 활성화 시간에 따른 비표면적은 3시간에서 최대를 보인 후 시간이 지속되면 비표면적은 감소하였다. 본 연구결과, 타이어열분해 잔류물 char를 이용한 활성탄 제조에 있어 최적의 실험조건은 활성화 온도 $850^{\circ}C$, 활성화 시간 3시간, 승온속도 $5^{\circ}C/min$이었으며 이 조건에서 제조한 활성탄의 비표면적은 $517.6m^2/g$으로 나타났다.

• Geomechanics and Engineering
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• v.22 no.3
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• pp.197-206
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• 2020

Reutilization of solid waste such as Tire Derived Aggregate (TDA) and mixing it with soft soil for backfill material not only reduces the required volume of backfill soil (i.e., sand-mining procedures; reinforcement), but also preserves the environment from pollution by recycling. TDA is a widely-used material that has a good track record for improving sustainable construction. This paper attempted to investigate the performance of Kaolin-TDA mixtures as a backfill material underneath a strip footing and close to a retaining wall. For this purpose, different types of TDA i.e., powdery, shredded, small-size granular (1-4 mm) and large-size granular (5-8 mm), were mixed with Kaolin at 0, 20, 40, and 60% by weight. Static surcharge load with the rate of 10 kPa per min was applied on the strip footing until the failure of footing happened. The behaviour of samples K80-G (1-4 mm) 20 and K80-G (5-8 mm) 20 were identical to that of pure Kaolin, except that the maximum footing stress had grown by roughly three times (300-310 kPa). Therefore, it can be concluded that the total flexibility of the backfill and shear strength of the strip footing have been increased by adding the TDA. The results indicate that, a significant increase in the failure vertical stress of the footing is observed at the optimum mixture content. In addition, the TDA increases the elasticity behaviour of the backfill.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.195-206
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• 1979

Where the industrial waste is increasing in number of kind and in quantities by the industrialization and population increases, the pollution problem is not only national but grobal question of the day. This paper is trying to invite attentions by the people who are working in both sector-natural sciences and industries in reviewing limited reports and materials. 1. By the chemical evaluation of over 20 industrial waste produced in Korea, potential wastes for commercial fertilizer would be wastes from alcohol fermantation, beer brewery, leather processing, synthetic fiber, and coffee grounds. 2. The composition of city waste is differ from other countries and sludge cake from human feces processing is promising one in the organic matter and phosphate content particularly. However, the content of heavy matals, specific order, and availability of phosphate are the bottle-neck for the development. 3. There is one commercial fertilizer from industrial waste in the market. It is very reasonable in the content of nitrogen and organic matter, and its formulation and responeses on crops. 4. Discussions were also given on the general problems in processing and marketing of fertilizers from industrial waste, however, scientists and industrial owners have to pay more attention on the development of fertilizers from tire industrial wastes because of vital environmental protection view-point.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.789-797
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• 2008

This study was conducted to investigate removal characteristics of gaseous trimethylamine(TMA) through biofilter packed with waste tire-chips. The sludge in this experiment was collected from an activated sludge operated in a wastewater treatment facility treating malodorous pollutants. The nominal amount of collected sludge was inoculated through packing materials in the filter. The removal efficiencies for varying concentrations and SVs(Space velocity) were assessed based on TMA, COD$_{Cr}$, NO$_3{^-}$-N, NO$_2{^-}$-N, NH$_4{^+}$-N and EPS(Extracellular Polymeric Substances) in leachate, since biofilter had been steady-stately operated. The influent concentration of 10 ppm of TMA was removed to approximately 95% regardless of changing SV at 120 and 180 hr$^{-1}$, but it was lowered to 80 to 90% at SV 240 hr$^{-1}$. As influent concentration was gradually increased from 5 to 55 ppm, the removal efficiencies of TMA were initially high for 95% in the range of 5 to 10 ppm, but lowered to 80% for 10 to 30 ppm. As a part of kinetic study for TMA decomposition, V$_m$(maximum substrate removal rate) and $K_s$(substrate infinity coefficient) were 14.3 g$\cdot$m$^{-3}$$\cdot$h$^{-1}$ and 0.043 g$\cdot$m$^{-3}$, respectively while adapted period was shown in the range of 100 to 150 hr. Also, the EPS concentration was consistently observed from the leachate showing 100 to 200 ppm, which indicates that biofilm has been continuously formed and sustained throughout tire-chips packed reactor.