• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.281-283
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• 2008

The superconducting fault current limiter (SFCL) using magnetic coupling of two coils with series connection, which was suggested by us, has the merit to increase the operational current and the limiting impedance of the SFCL through the adjustment of the inductance ratio and the winding direction of two coils. In addition, the recovery characteristics of the SFCL is affected by the winding direction of two coils as well as two coils' inductance ratio. In this paper, the fault current limiting and recovery characteristics of a SFCL using magnetic coupling of two coils with series connection were analyzed. Through the analysis based on the experimental results, the recovery characteristics and the current limiting characteristics of the SFCL were confirmed to be improved more in case of the additive polarity winding.

• Resources Recycling
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• v.33 no.1
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• pp.15-21
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• 2024

The demand for electric vehicles powered by lithium-ion batteries is continuously increasing. Recovery of valuable metals from waste lithium-ion batteries will be necessary in the future. This research investigated the effect of reaction temperature on the lithium recovery ratio from hydrogen reduction followed by water leaching from lithium-ion battery NCM-based cathode materials. As the reaction temperature increased, the weight loss ratio observed after initiation increased rapidly owing to hydrogen reduction of NiO and CoO; at the same time, the H₂O amount generated increased. Above 602 ℃, the anode materials Ni and Co were reduced and existed in the metallic phases. As the hydrogen reduction temperature was increased, the Li recovery ratio also increased; at 704 ℃ and above, the Li recovery ratio reached a maximum of approximately 92%. Therefore, it is expected that Li can be selectively recovered by hydrogen reduction as a waste lithium-ion battery pretreatment, and the residue can be reprocessed to efficiently separate and recover valuable metals.

• Korean Journal of Acupuncture
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• v.32 no.1
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• pp.20-29
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• 2015

Objectives : The objectives of this study is to compare the effects of electroacupuncture(EA), warm needling(WN) and Radio Frequency warm needling(RFWN) stimulations on the acupoints at the artificially damaged ankles of Sprague-Dawley rats, which could be classified as the Grade 3. Methods : The foot weight bearing force ratio(FWBFR) of ankle sprain was measured first at 24 hours after without any other stimulations. Pain Recovery Index(PRI) represents the analgesic level, and modified Pain Recovery Index(mPRI) shows the accumulated recovery level. PRI was measured at 2 hours after each stimulus on GB34, GB39 and GB42, and mPRI was during 7 days. Results : EA stimulation of GB34 and GB39 acupoint in grade 3 ankle sprain showed a marked analgesic and recovery effect. RFWN of GB42 exhibited significant analgesic and pain recovery effect. RFWN of GB34 resulted in pain recovery effect but not analgesic effects, and RFWN of GB39 resulted in analgesic effect 2 hours after but not pain recovery. However, WN did not affect the pain recovery among three acupoints at all. Conclusions : In the Grade 3 ankle sprain model, the difference of analgesic effects were explained by the acupoints and the stimulation methods according to the accumulated recovery effects during 7 days. It is insufficient to determine that a certain acupoint has a specific analgesic effect depending on the stimulation method by the results of this study. Therefore, the effects of each stimulation on the acupoints in any other meridians at the sprained ankle should be compared and analyzed.

• Resources Recycling
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• v.30 no.6
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• pp.61-67
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• 2021

This work investigated the cementation of iridium from iridium-containing hydrochloric acid leachate. Zinc powder was used as the reducing agent, and the effects of the stoichiometric ratio of Zn/Ir, initial Ir concentration, initial pH, reaction time, and ultrasound irradiation on iridium recovery were investigated. When only the stirrer was used for cementation, the iridium recovery increased with the addition amount of zinc, and the recovery of about 70% at 40 times the stoichiometric ratio of Zn/Ir. In contrast, when employing ultrasonic irradiation with stirring, the recovery of iridium decreased at 20 times or less the stoichiometric amount of zinc. The recovery of iridium increased at 40 times the stoichiometric ratio of Zn/Ir. This result may be due to the ionization of zinc and re-dissolution of iridium during the ultrasound irradiation treatment. When a combination of ultrasonic irradiation and stirring was used for cementation, the iridium recovery increased by more than 27% compared to that when using only the stirrer. It was possible to recover 99% of iridium under the following conditions: reaction time, 60 min; initial pH, 0.01; volume of leachate, 100 mL; 1770 ppm Ir, 40 times the stoichiometric ratio of Zn/Ir.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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• pp.8-20
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• 2006

For large scale separation hydrogen from different mixing ratio(60/40 and 80/20 vol.%) of hydrogen and methane $1Nm^3/hr$ and $4Nm^3/hr$ 2bed-6step pressure swing adsorption(PSA) process was used, respectively. The effects of the feed gas pressure, adsorption time, the feed flow rate and the P/F(purge to feed) ratio on the process performance were evaluated. In the $1Nm^3/hr$ PSA results, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75 % recovery and 99 % purity hydrogen in these processing. The optimum feed flowrate was 22 LPM and 17 LPM in the ratio 60/40 and 80/20, respectively. In the $4Nm^3/hr$ PSA results, 10 atm adsorption pressure might be simulated values to obtain more than 80 % recovery and 99 % purity hydrogen in these processing.

• Journal of Power Electronics
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• v.19 no.3
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• pp.645-654
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• 2019

In this paper, a new high step up DC/DC converter with a modified super-lift technique is presented. The coupled inductor technique is combined with the super-lift technique to provide a tenfold or more voltage gain with a proper duty cycle and a low turn ratio. Due to a high conversion ratio, the voltage stress on the semiconductor devices is reduced. As a result, low voltage ultra-fast recovery diodes and low on resistance MOSFET can be used, which improves the reverse recovery problems and conduction losses. This converter employs a passive clamp circuit to recycle the energy stored in the leakage inductance. The proposed convertor features a high conversion ratio with a low turn ratio, low voltage stress, low reverse recovery losses, omission of the inrush currents of the switch capacitor loops, high efficiency, small volume and reduced cost. This converter is suitable for renewable energy applications. The operational principle and a steady-state analysis of the proposed converter are presented in details. A 200W, 30V input, 380V output laboratory prototype circuit is implemented to confirm the theoretical analysis.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.13-14
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• 2013

The aim of this study is to investigate the parametric characteristics on regenerative system with oxy-fuel combustion by experiment. Regenerative system with a pair of oxygen burners and regenerators is used for evaluating regenerator characteristics according to design parameters such as ball (regenerator medium) size, regenerator weight, and bypass of exhaust gas. The temperature profiles with time are varied by ball size and regenerator weight. The bypass of exhaust gas shows that the heat recovery ratio increases while the regenerating temperature efficiency slightly decreases.

• Journal of Power Electronics
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• v.6 no.3
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• pp.205-213
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• 2006

A cost-effective magnetic-coupled AC-PDP sustain driver with low switching loss is proposed. The transformer reduces current stress in the energy recovery switches which affects circuit cost and reliability. The turns-ratio can be used to adjust the sustain pulse slopes which affect gas discharge uniformity. Dividing the recovery paths prevents abrupt changes in the output capacitance and thereby switching losses of the recovery switches is reduced. In addition, the proposed circuit has a more simple structure because it does not use the recovery path diodes which also afford a large recovery current. By reducing the current stress and device count in the energy recovery circuit, the proposed driver may have decreased circuit cost and improved circuit reliability.

• Resources Recycling
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• v.24 no.5
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• pp.33-39
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• 2015

A basic study was conducted to effectively recover nitric acid from a waste solder stripper by diffusion dialysis using anion exchange membranes. The effects of flow rate, flux ratio, nitrate concentration, and metallic ion types and concentration on the recovery percentage of nitric acid were investigated. The recovery percentage of nitric acid was decreased with the increase of flow velocity. But the recovery percentage of nitric acid was increased as the increase of flux ratio(W/F) and showing a recovery percentage of nitric acid of about 99% at a flux ratio of 1.5 or more. As the increase of nitric acid concentration in feed solution, the recovery percentage of nitric acid was increased up to 3.0M, but in case of greater than 3.0M, the recovery percentage gradually was decreased. Leakage percentage of metallic ions through the membrane were in the order of Pb, Na and Cu but Fe and Sn did not leakaged. As a result of diffusion dialysis using real waste solder stripper at a flow rate of $0.9L/hr-m^2$, W/F = 1.3, a recovery percentage of nitric acid of approximately 94% was gained.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.78-85
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• 2006

In textile industries, waste effluent containing zinc is generated during the manufacture of rayon yarn from the wood pulp or cotton linters. Due to the strict environmental regulations and the presence of toxic metallic and other constituents, the discharge of industrial effluents in the sewage or disposal of solid sludge as landfill is restricted. Before recycling of zinc as zinc sulphate solution to the spinning-bath of the rayon manufacturing plant the zinc sulphate solution must be free from calcium, which is deleterious to the process as gypsum precipitates with the increase in concentration and forms scale in the bath. In the present work an attempt has been made to develop a process following solvent extraction technique using thiophosphinic extractants, Cyanex 272 and 302 modified with isodecanol and diluted in kerosene to recover zinc from rayon effluent. Various process parameters viz. extraction of zinc from different concentration of solution, distribution ratio, selective extraction, O/A ratio on extraction and stripping from the loaded organic, complex formation in the organic phase etc. have been studied to see the feasibility of the process. The extractant Cyanex 302 has been found selective for the recovery of 99.99% of zinc from the effluent above equilibrium pH 3.4 maintaining the O/A ratio of 1/30 leaving all the calcium in the raffinate. It selectively extracted zinc in the form of complex $[R_{2}Zn.3RH]_{org}$ and retained all the calcium in the aqueous raffinate. The zinc from the loaded Cyanex 302 can be stripped with 10% sulphuric acid at even O/A ratio of 10 without affecting the stripping efficiency. The stripped solution thus obtained could be recycled in the spinning bath of the rayon plant. The raffinate obtained after the recovery of zinc could be disposed safely without affacting environment.