• Environmental Engineering Research
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• v.18 no.3
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• pp.177-189
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• 2013

Studies were carried out on the speciation of heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr) during rotary drum composting of water hyacinth (Eichhornia crassipes) for a period of 20 days. Five different proportions of cattle manure, water hyacinth and sawdust were prepared for composting. This study concluded that, rotary drum was very efficient for the degradation of organic matter as well as for the reduction of mobility and bioavailability of heavy metals during water hyacinth composting. The results from the sequential extraction procedure of heavy metals shows that rotary drum composting changed the distribution of five fractions of Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr. The highest reduction in the bioavailability factors of Pb and Cd was observed during the process. The total concentration of Cu, Cr, and Cd was very low compared to the other metals (Zn, Mn, Fe, Ni, and Pb); however, the percentage of exchangeable and carbonate fractions of these metals was similar to other metals. These results confirmed that the bioavailability of metals does not depend on the total concentration of metals. From this study, it can be concluded that the addition of an appropriate proportion of cattle manure significantly reduced the mobile and easily available fractions (exchangeable and carbonate fractions) during water hyacinth composting in rotary drum.

• Smart Structures and Systems
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• v.17 no.2
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• pp.275-296
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• 2016

This paper focuses on developing a new configuration on magnetorheological (MR) brake damper as prosthetic knee. Prosthetic knee uses magnetic fields to vary the viscosity of the MR fluid, and thereby its flexion resistance. Exerted transmissibility torque of the knee greatly depends on the magnetic field intensity in the MR fluid. In this study a rotary damper using MR fluid is addressed in which a single rotary disc will act as a brake while MR fluid is activated by magnetic field in different walking gait. The main objective of this study is to investigate a prosthetic knee with one activating rotary disc to accomplish necessary braking torque in walking gait via T-shaped drum with arc surface boundary and implementing of Newton's equation of motion to derive generated torque at the inner surface of the rotary drum. For this purpose a novel configuration of a T-shaped drum based on the effects of a material deformation process is proposed. In this new design, the T-shaped disc will increase the effective areas of influences in between drum and MR fluid together and the arc wall crushes the particles chains (fibrils) of the MR fluid together instead of breaking them via strain in a conventional MR brake. To verify the proposed MR brake, results of the proposed and conventional MR brakes are compared together and demonstrated that the resisting torque of the proposed MR brake is almost two times greater than that of the conventional brake.

• Environmental Engineering Research
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• v.20 no.3
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• pp.212-222
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• 2015

Experiments were conducted on the immobilization of eight heavy metals (HMs) (Zn, Cu, Mn, Fe, Ni, Pb, Cd, and Cr) during 20-day rotary drum composting of water hyacinth. The Tessier sequential extraction procedure was used to investigate the fractionation of HMs. The eco-toxicity risk of HMs was assessed by risk assessment code (RAC). In the results, the bioavailability factor (BAF) for different HMs presented in the following order: Mn > Zn = Fe > Cu > Cr > Cd = Pb > Ni. The total concentration of Pb was higher than that of Zn, Cu, Mn, Cd and Cr; however, its BAF was the lowest among these HMs. These results confirmed that the eco-toxicity of HMs depends on bioavailable fractions rather than on the total concentration. The greatest reduction in bioavailability and eco-toxicity risk of HMs occurred in lime 1% and 2% as compared to control and lime 3%. The eco-toxicity risk of Fe, Ni, Pb, Cd and Cr was reduced from low risk to zero risk by rotary drum composting. These studies demonstrated the high efficiency of the rotary drum for degrading compost materials and for reducing the bioavailability and eco-toxicity risk of HMs during the composting process.

• Journal of Animal Environmental Science
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• v.11 no.1
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• pp.61-70
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• 2005

A total of 4 trials were conducted to evaluate the nutritional value of food waste-byproduct feeds mixture(FWM) rotary drum-pasteurized and cured, to trace the nutritional flow according to the processing stages and finally to determine the optimal mixing formulation of feed ingredients for the growing pigs. Pasteurizing and curing FWM using a rotary drum drier resulted in little change in chemical composition and 8 to $15 \%$ of dry matter losses. Chemical change was affected by different feed ingredients used in each trial. Curding of FWM was caused probably by high moisture content, starch content and(or) physical characteristics of feed ingredients. The optimal mixing ratio of feed ingredients was food waste 45 : deepstacked broiler litter 10 : bakery by-product 22.5 barley bran 22.5. In conclusion, FWM rotary drum-pasteurized and cured had a satisfactory feed-nutritional value far growing pigs.

• Environmental Engineering Research
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• v.19 no.1
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• pp.47-57
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• 2014

The aim of this paper was to study the effect of five different waste combinations (C/N 15, C/N 20, C/N 25, C/N 30, and control) of sewage sludge coupled with sawdust and cattle manure in a pilot scale rotary drum reactor, during 20 days of the composting process. Our results showed that C/N 30 possesses a higher temperature regime with higher % reduction in moisture content, total organic carbon, soluble biochemical oxygen demand and chemical oxygen demand; and higher % gain in total nitrogen and phosphorus at the end of the composting period implying the total amount of biodegradable organic material is stabilized. In addition, $CO_2$ evolution and oxygen uptake rate decreased during the process, reflecting the stable behavior of the final compost. A Solvita maturity index of 8 indicated that the compost was stable and ready for usage as a soil conditioner. The results indicated that composting can be an alternate technology for the management of sewage sludge disposal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.181-185
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• 2001

This paper deals with the dynamic stability of a disc brake pad taking into account of its shear deformation and rotary inertia. A brake pad can be modeled as a beam like model subjected to distributed friction forces and having two translational springs. The study of this model is intended to provide a fundamental understanding of dynamic stability of drum brake pad. Governing equations of motion are derived from extended Hamilton's principle and their corresponding numerical solutions are obtained by applying the finite element formulation. The critical distributed friction force and the instability types are investigated bt changing two translational spring constants, rotary inertia parameter and shear deformation parameter. Also, the changes of eigen-frequencies of a beam determining instability types are investigated for various combinations of two translational spring constants.

• Environmental Engineering Research
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• v.17 no.2
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• pp.69-75
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• 2012

Composting of water hyacinth, mixed with cattle manure, rice husk and sawdust in four different proportions, was performed in a pilot scale rotary drum composter. The physico-chemical characteristics, i.e., temperature, moisture content, pH, electrical conductivity, total organic matter (OM), nitrogen dynamics and nutrients were evaluated during the 20 days composting process. The stabilities of the composts were also investigated with respirometric analysis, i.e., $CO_2$ evolution rates and oxygen uptake rate (OUR). Among all trials, trial 1 (6 water hyacinth, 3 cattle manure, 1 rice husk) indicated the best composting mix, as shown by the highest temperature profile and OM loss, and lowest $CO_2$ evolution rate and OUR.

• Environmental Engineering Research
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• v.19 no.1
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• pp.67-73
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• 2014

In India, disposal of vegetable market waste along with municipal solid waste in landfills or dumpsites is creating much nuisance in terms of odor nuisance, leachate production, and greenhouse gas emission into the atmosphere. Therefore, vegetable waste with high biodegradable and nutrient content is composted in a 550-L batch scale rotary drum composter to study the degradation process and its compost properties for its potential reuse as high quality compost. A total 150 kg of working volume was fixed for composting studies with two different ratios, trial A (6:3:1) of C/N 24 and trial B (8:1:1) of C/N 30, respectively. A maximum of $63.5^{\circ}C$ and $61.2^{\circ}C$ was observed in trials A and B; an average of $55^{\circ}C$ for more than 5 days, which helped in the degradation of organic matter and reduction of total and fecal coliform. The temperature dropped suddenly after the thermophilic stage in trial B, and leachate was observed due to insufficient amount of bulking agent. Mesophilic bacteria dominated during the initial stages of composting, and reduced considerably during the thermophilic stage. During the thermophilic stage, the rise in spore-forming organisms, including spore-forming bacteria, fungi, actinomycetes and streptomycetes, increased and these were predominant until the end of the composting process. By examination, it was observed that moisture and leachate production had adverse effects on the compost parameters with higher loss of micronutrients and heavy metals.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.57-65
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• 2008

The atomization phenomena and spray characteristics of drum type rotary atomizer using centrifugal force from high rotational speed of gas turbine engine shaft were studied through rotary atomizer modeling analysis and experimental method. A test rig for rotary atomization that has range of $5,000{\sim}40,000\;rpm$ was used to make similarity for high speed rotating shaft. Spray visualization methodology and Phase Doppler Anemometry were also used to investigate the atomization mechanism and spray characteristics. We found that the rotating fuel spray has unique breakup process and we have to make breakup point earlier through increasing rotating speed to improve atomization performance.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.51-57
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• 2005

In order to prevent the environmental pollution, the dryers are commonly used to treat sludge that one of sewages is polluting the quality of water. Generally, the drying method is various as to the property of material and use. Rotary dryer is a good apparatus to treat them. The rotary dryer is the way that is to make substance transmission and heating using hot air between sludge particles and heated gas. In this paper, we performed a numerical analysis of the inner air flow of the 3-pass rotary dryer through the changing rotational speed from 3rpm to 10rpm. In this result, we found that 3rpm is effective to dry material in terms of heat transfer because large scale velocity fluctuation is occurred inside the first and second drum. Also we confirmed that 5rpm and 8rpm showed up uniform flow at the center area of the first drum.