• Journal of Korean Institute of Industrial Engineers
• /
• v.34 no.3
• /
• pp.270-288
• /
• 2008

Among various environmental issues, those for worn-out products are increasingly important due to rapid development and improvement of products, shortages of dumping sites and waste-incineration facilities, and legislation pressures and customer recognitions to protect the environment. Under such circumstances, collection and product recovery activities give rise to additional material flows from customers back to collectors and reprocessors. Reverse logistics, the opposite direction of the conventional forward logistics, is concerned with the management of this material flow. In this paper, we consider the emerging concept of reverse logistics. First, the concept of sustainable development is explained to explain the philosophical background of various environmental issues. Second, we explain the basics of reverse logistics, which includes the overall structure and the classification of network types. Finally, we review the previous research articles, especially in the aspect of industrial engineering, after classifying the decision problems into : (a) product recovery strategy; (b) network design and operation; (c) inventory management; (d) disassembly problems; and (e) remanufacturing problems.

• Restorative Dentistry and Endodontics
• /
• v.10 no.1
• /
• pp.7-16
• /
• 1984

The purpose of this study was to investigate the pulpal responses to adhesive resins as phosphoric ester system: "Clearfil F II" (Composite filling material), "Panavia EX" (Composite cementing Material) and "Silar" (Microfilled Compsoite resin) comparing with Zinc-Oxide-Eugenol cement. Total 70 cavities of the permanent healthy teeth from 5 dogs were prepared and placed with experimental resins and Zinc-Oxide-Eugenol cement as control. The dogs were sarificed at 5 intervals of 3 days, one, two, four, six weeks. The specimens were routinely prepared and stained by Hematoxylin-Eosin. Followings were the results obtained through microscopic examination. 1. In cases of Clearfil F II and Panavia EX without etching and lining, pulp response in the early stage showed more severe vascular congestion and hemorrhage than that of Zinc-Oxide-Engenol cement. 2. The pulp response of totally etched cases was similar to that of unetched cases in the groups of Clearfil F II and Panavia EX. 3. The cases of Clearfil F II and Panavia EX with enamel etching showed no significant histologic change compared to that of total cavity etching. 4. The Silar case with total etching showed retarded tendency of histologic recovery compared to Clearfil F II and Panavia EX group. 5. Generally, pulp responses of experimental groups were not severe and the six week case showed the evidence of a histologic recovery.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.1
• /
• pp.68-72
• /
• 2013

The series connection-type superconducting fault current limiter (SFCL) with two magnetically coupled circuits was suggested and its effectiveness through the analysis on the current limiting and recovery characteristics was described. The fault current limiting characteristics of the proposed SFCL as well as the load voltage sag compensating characteristics according to the winding direction were investigated. To confirm the fault current limiting and the voltage sag suppressing characteristics of the this SFCL, the short-circuit tests for the simulated power system with the series connection-type SFCL were carried out. The series connection-type SFCL designed with the additive polarity winding was shown to perform more effective fault current limiting and load voltage sag compensating operations through the fast quench occurrence right after the fault appears and the fast recovery operation after the fault removes than that with the subtractive polarity winding.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.12
• /
• pp.992-995
• /
• 2018

The wireless charging of body-embedded medical instruments and wireless power transfer to various inside dielectric-materials is still a future technology that has not yet been achieved. This paper proposes methods for controlling the capacitance of the resonators and installing air pockets on the top and bottom sides of the resonators for optimal design, which considered efficiency and resonant frequency in accordance with the electromagnetic characteristics of the dielectric medium. In future, the results of this research will be utilized as the basic research data to design and restore resonant frequency of resonators embedded in various dielectric environments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.5
• /
• pp.345-350
• /
• 2018

Nanomaterials have considerable potential to solve several key challenges in various electrochemical devices, such as fuel cells. However, the use of nanoparticles in high-temperature devices like solid-oxide fuel cells (SOFCs) is considered problematic because the nanostructured surface typically prepared by deposition techniques may easily coarsen and thus deactivate, especially when used in high-temperature redox conditions. Herein we report the synthesis of a self-regenerated Pd metal nanoparticle on the perovskite oxide anode surface for SOFCs that exhibit self-recovery from their degradation in redox cycle and $CH_4$ fuel running. Using Pd-doped perovskite, $La(Sr)Fe(Mn,Pd)O_3$, as an anode, fairly high maximum power densities of 0.5 and $0.2cm^{-2}$ were achieved at 1,073 K in $H_2$ and $CH_4$ respectively, despite using thick electrolyte support-type cell. Long-term stability was also examined in $CH_4$ and the redox cycle, when the anode is exposed to air. The cell with Pd-doped perovskite anode had high tolerance against re-oxidation and recovered the behavior of anodic performance from catalytic degradation. This recovery of power density can be explained by the surface segregation of Pd nanoparticles, which are self-recovered via re-oxidation and reduction. In addition, self-recovery of the anode by oxidation treatment was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05b
• /
• pp.8-11
• /
• 2001

In this study. the recovery of plasma induced damage in the etched PZT thin film with $O_2$ re-annealing have been investigated. The PZT thin films were etched as a function of $Cl_2/Ar$ and additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etch rates of PZT thin films were $1600\dot{A}/min$ at $Cl_{2}(80%)/Ar(20)%$ gas mixing ratio and $1970\dot{A}/min$ at 30 % additive $CF_4$ into $Cl_{2}(80%)/Ar(20)%$. The etched profile of PZT films was obtained above 70 by SEM. In order to recovery properties of PZT thin films after etching, the etched PZT thin films were re-annealed at various temperatures in $O_2$ atmosphere. From the hysteresis curves, ferroelectrical properties are improved by $O_2$ re-annealing process. The improvement of ferroelectric behavior at annealed sample is consistent with the increase of the (100) and (200) PZT phase revealed by x-ray diffraction (XRD). From XPS analysis, intensity of Pb-O, Zr-O and Ti-O peak are increased and the chemical residue peak is reduced by $O_2$ re-annealing. The ferroelectric behavior consistent with the dielectric nature of TixOy is recovered by $O_2$ recombination during rapid thermal annealing process. From AFM images, it shows that the surface roughness of re-annealed sample after etching is improved.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.4
• /
• pp.458-465
• /
• 2017

The purpose of the present study was to examine the method of physically processing oyster shells for use as raw material(aggregate) through experimentation. The results of the experiment found that the adequate particle size of the pulverized oyster shells should be smaller than 10mm due to their shape. Also, after considering various particle size distributions and residual rates by particle size, the study found the cutter mill to be the most suitable tool for pulverizing oyster shells. The use of a cutter mill resulted in recovery rates of 97.3%, 98.2%, and 98.9% for inner screens of 8mm, 12mm, and 20mm respectively, revealing how the increase of screen size results in slightly higher recovery rates. The experiment involving the difference between the inner screen of the cutter mill and the speed of the inverter shows that a smaller screen size and a faster inverter speed result in a lower fineness modulus, while a rise in inverter speed for an identical screen made possible the material recovery of a much lower range of particle sizes.

• Resources Recycling
• /
• v.22 no.4
• /
• pp.3-11
• /
• 2013

The recovery of molybdenum and vanadium from acid leaching solutions of spent catalysts using solvent extraction has been investigated. Among various acid leaching solutions, sulfuric acid solution is found to be adequate for the recovery of these two metals. The extraction and stripping behavior of the two metals in the absence and presence of other impurity metals by various types of extractants such as cationic, solvating, amine and a mixture of cationic and solvating extractants was discussed. Each type of extractants has advantage and disadvantage in terms of the possibility of separation and of forming a third phase. Among the various types of extractants, a mixture of cationic and solvating extractants seems to be the most promising extractant system for the separation of Mo and V from the acid leaching solutions of spent catalysts.

• Environmental Engineering Research
• /
• v.25 no.1
• /
• pp.88-95
• /
• 2020

An investigation of rare metals recovery from LiNi_xCo_yMn_zO₂ cathode material of the end-of-life lithium-ion batteries is presented. To determine the influence of reductant on the leach process, the cathode material (containing Li 7.6%, Co 20.4%, Mn 19.4%, and Ni 19.3%) was leached in H₂SO₄ solutions either with or without H₂O₂. The optimal process parameters with respect to acid concentration, addition dosage of H₂O₂, temperature, and the leaching time were found to be 2.0 M H₂SO₄, 4 vol.% H₂O₂, 70℃, and 150 min, respectively. The yield of metal values in the leach liquor was > 99%. The leach liquor was subsequently treated by precipitation techniques to recover nickel as Ni(C₄H₇N₂O₂)₂ and lithium as Li₂CO₃ with stoichiometric ratios of 2:1 and 1.2:1 of dimethylglyoxime:Ni and Na₂CO₃:Li, respectively. Cobalt was recovered by solvent extraction following a 3-stage process using Na-Cyanex 272 at pH_eq ~5.0 with an organic-to-aqueous phase ratio (O/A) of 2/3. The loaded organic phase was stripped with 2.0 M H₂SO₄ at an O/A ratio of 8/1 to yield a solution of 114 g/L CoSO₄; finally recovered CoSO₄.xH₂O by crystallization. The process economics were analyzed and found to be viable with a margin of $476 per ton of the cathode material.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.273-280
• /
• 2023

The purpose of this study is to investigate the effect of functional bedding of ceravida recovery materials on muscle fatigue, brain waves, and heat in the cervical spine before and after sleep. The subjects of the study were 12 women in their 50s or older in D Metropolitan City who complained of insomnia due to sleep disorders and cervical pain. The results of this study first showed that functional bedding lowered muscle tension. Second, the skin temperature of cervical spine increased statistically significantly for both functional and general bedding. Third, there was a statistically significant difference in EEG(alpha, beta, theta, delta) of functional bedding. Through these results, it is considered that functional bedding of ceravida recovery material has sufficient effect on sleep recovery technology.