• Resources Recycling
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• v.19 no.6
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• pp.51-60
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• 2010

A study on the recovery of cobalt and lithium from Lithium Ion Battery(LIB) scraps has been carried out by a physical treatment - leaching - solvent extraction process. The cathode scraps of LIB in production were used as a material of this experiment. The best condition for recovering cobalt from the anode scraps was acquired in each process. The cathode scraps are dissolved in 2M sulfuric acid solution with hydrogen peroxide at $95^{\circ}C$, 700 rpm. The cobalt is concentrated from the leaching solution by means of a solvent extraction circuit with bis(2-ethylhexyl) phosphoric acid(D2EHPA) and PC88A in kerosene, and then cobalt and lithium are recovered as cobalt hydroxide and lithium carbonate by precipitation technology. The purity of cobalt oxide powder was over 99.98% and the average particle size after milling was about 10 lim. The over all recoveries are over 95% for cobalt and lithium. The pilot test of mechanical separation was carried out for the recovery of cobalt from the scraps. The $Co_3O_4$ powder was made by the heat treatment of $Co(OH)_2$ and the average particle size was about 10 ${\mu}m$ after grinding. The recovery was over 99% for cobalt and lithium each other and the purity of cobalt oxide was over 99.98%.

• Resources Recycling
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• v.21 no.2
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• pp.3-8
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• 2012

In the points of the environmental conservation and the recirculating utilization of limited resources, it is very important to recover valuable metals like Au, Ag, Pd, Cu, Sn, Ni, Co, and Li used as industrial raw materials from urban ores. From now, many processes have been developed for recovering the valuable metals contained in urban ores and some of them have been operated commercially. In the paper, pyrometallurgical processes developed for reclaiming valuable metals from urban ores will be briefly introduced.

• Resources Recycling
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• v.30 no.5
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• pp.38-48
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• 2021

In this study, we determine the optimal process conditions for selectively recovering Si from a solar cell surface by removal of impurities (Al, Zn, Ag, etc.). To selectively recover Si from solar cells, leaching is performed using HCl solution and an ultrasonic cleaner. After leaching, the solar cells are washed using distilled water and dried in an oven. Decompression filtration is performed on the HCl solution, and ICP-OES (Inductively Coupled Plasma Optical Emission spectroscopy) full scan analysis is performed on the filtered solution. Furthermore, XRD (X-ray powder diffraction), XRF (X-ray fluorescence), and ICP-OES are performed on the dried solar cells after crushing, and the purity and recovery rate of Si are obtained. In this experiment, the concentration of acid solution, reaction temperature, reaction time, and ultrasonic intensity are considered as variables. The results show that the optimal process conditions for the selective recovery of Si from the solar cells are as follows: the concentration of acid solution = 3 M HCl, reaction temperature = 60℃, reaction time = 120 min, and ultrasonic intensity = 150 W. Further, the Si purity and recovery rate are 99.85 and 99.24%, respectively.

• Resources Recycling
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• v.29 no.6
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• pp.125-132
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• 2020

Enrichment possibilities for recovering rare earth elements contained in coal bottom ash generated from domestic circulating fluidized bed combustion (CFBC) were identified. The transport characteristics of the REEs according to the separation and removal of major minerals were evaluated using sieving and leaching process. The main minerals of bottom ash were identified as anhydrite, magnetite, and quartz, and this was confirmed as a 30% of REE content of the world's average coal ash REE value (404 ppm) as a result of the difference in the combustion characteristics of power plants (REE contents in starting material: 123 ppm). More than 90% of the REEs contained in the bottom ash were found to move mainly with magnetite, and less than 10% of the components were found to move with the quartz. Therefore, In order to recover rare earth elements from coal bottom ashes generated from CFBC boiler, it is necessary to select the main rare elements such as magnetite and develop a pretreatment and concentration process.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.59-66
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• 2022

Lithium-ion batteries have greatly expanded along with the mobile phone market, and as the electric vehicle business is activated in earnest, they will attract many people's attention even afterwards. Until now, many people have attracted attention to the recovery of valuable metals inside lithium-ion batteries, but graphite, which is mainly used as an anode material, is also worth recycling. Therefore, in order to recover graphite with high purity and valuable metals, graphite that can be used as an anode material of a secondary battery may be generated again through a regeneration process of purifying and separating graphite from a waste lithium-ion battery and recovering electrical characteristics of graphite. This paper describes the process of converting waste graphite into regenerated graphite and the environmental and economic effects of regenerated graphite.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.6
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• pp.17-29
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• 2021

Recently, as social distancing have been raised due to the re-spread of COVID-19, the number of serial entrepreneurs who are closing their business is rapidly increasing. Learning from failure is a source of success, but business failure can result in psychological and economic losses and negative emotions of the serial entrepreneur. At this point, it is very important to find a way to recover the negative emotions caused by business failures of serial entrepreneurs. Recently, a strategic model has emerged to deal with the negative emotions of grief caused by business failures of serial entrepreneurs. This study identified the recovery factors from the grief of business failures of serial entrepreneurs and analyzed Shepherd's(2003) three areas: loss orientation, restoration orientation, and dual process. To this end, individual in-depth interviews were conducted with 12 small business serial entrepreneurs who challenged re-startup to identify the attributes of recovery factors that were not identified with quantitative data. As a result of the study, first, recovery factors were investigated in three areas: individual orientation, family orientation, and network orientation. It was found to help improve recovery in nine categories: self-esteem, persistence, personal competence, hobbies, self-confidence, family support, networks, religion, and social support. Second, recovery obstacle factors were investigated in three areas: psychological, economic, and environmental factors. Nine categories including family, health, social network, business partner, competitor, partner, fund, external environment, and government policy were found to persist negative emotions. Third, the emotional processing process for grief was investigated in three areas: loss orientation, restoration orientation, and dual process. Ten categories such as family, partner support, social member support, government support, hobbies, networks, change of business field, moving, third-party perspective, and meditation were confirmed to enhance rapid recovery in the emotional processing process for grief. The implications of this study are as follows. The process of recovering from the grief caused by business failures of serial entrepreneurs was attempted by a qualitative study. By extending the theory of Shepherd(2003), This study can be applied to help with recovery research. In addition, conceptual models and propositions for future empirical research were presented, which can be discussed in carious academic ways.

• Korean Journal of Social Welfare
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• v.64 no.3
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• pp.231-255
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• 2012

This study has aimed to observe the starting point of Korean social welfare studies with the perspective of historicism. Basically, this study has focused on the following research question; by what kind of influences and contents had been built Korean social welfare studies in the early days? The collected data from introductory texts which had been written by the first generation of Korean social welfare studies was analyzed according to the framework as follows; 1) historical summary of the texts, 2) individual historical disposition of the writers, 3) historical application of the principle terms, and 4) historical context of the contents for social welfare studies. As results, some issues related with the formation of Korean social welfare studies are stressed as follows; 1) data collecting from the first generation of the researchers and writers for recovering the introductory texts, 2) study of the influences of christianity, 3) study on the influences of aid agencies from oversees, 4) study on the influence of the mixed with American and Japanese social welfare studies, and 5) study on the examination of developing process of Korean social welfare studies afterward. Finally, the limit of this study that the individual history of writers could not cope detailed and deeply is mentioned.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.121-134
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• 2004

This article describes a clinical protocol for the conventional rehabilitation of patient diagnosed with partial anodontia. A combined dental therapy approach was used and included endodontic therapy and root capping on the maxillary central incisors, fabrication of a maxillary overdenture, and fabrication of mandibular konus overdenture supported by 3 konus abutments. Within this protocol, tooth-supported overdenture prostheses are used for 2 purposes: first, to obtain the most rigid retention and function at an established maxillary-mandibular relationship; and second, to continuously maintain function and esthetic appearance applying immediate dentures after teeth extraction. The idea behind this protocol and its associated clinical procedures is presented along with a discussion compared with implant therapy. In the case introduced, and after 7 years of observation, the therapy can be seen as a success. We increased the occlusal vertical height in this case, but it would be more appropriate to see this as recovering the occlusal vertical height that was lost. The process of increasing the occlusal vertical height, that is restoration of the face, modification of the extrinsic occlusion of the incisors, and retraction of the mandible is very difficult and important. Ultimately, class III malocclusion is fixed, adequate occlusal vertical height is gained, and the retracted posterior anodontial portion is restored by prosthodontic dentures based on the rigid support theory. The result of the therapy done on the later-achieved malocclusion with partial anodontia on the posterior portion must consider the following in order to maintain the safety of the esthetics of the tooth and face for a period of time: 1) occlusal restoration with an ideal occlusal vertical height, 2) allowance of the final occlusion induced by the functional relationship of the upper and lower jaw, 3)final occlusion functionally induced by the lip competence limit.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.6
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• pp.474-481
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• 2004

Squamous cell carcinoma is the most prevalent oral cancer, which is characterized by its low survival rate, high malignancy, mortality with facial defects, and poor prognosis. Exact cause and pathogenesis of the squamous cell carcinoma is still unknown. Various routes including smoking, radiation, and viral infections predispose its genesis, and recent studies revealed that genetic defects which fail to prevent cancer proliferation play a role. Generally, a cancer develops from the decreased rate of apoptosis which is an active and voluntary cell death, and from the altered cell cycles. Anticancer effect can be obtained by recovering the apoptotic process, and by suppressing the cell cycles. Among the apoptosis related factors, bcl-2, caspase-9, and VDAC (voltage-dependent anion channel)are produced in mitochondria of the cell. Cyclosporin-A is known to induce apoptosis through its activation with VDAC. This study was to reveal the anticancer effect of Cyclosporin A to the oral squamous cell carcinoma. The inverted microscope was used to find alterations in the tissue, and sensitivity test to the anticancer cells was performed with MTT (Tetrazolium-based colorimetric) assay. Following cell line culture of primary and metastastic oral squamous cell carcinoma, electrophoresis was performed with extracted total RNA. Finally, semi-quantitative study was carried out through RT-PCR (Reverse Transcription-Polymerase Chain Reaction). The results of this study are as follows: 1. The inverted microscopic observation revealed a poorly defined cytoplasm at $2000ng{\sim}3000ng/ml$, indistinct nucleus, and apoptosis. 2. The Growth of cancer cells was decreased at 1000ng/ml of cyclosporin-A. No cancer cell growth was observed at over 2000ng/ml concentration of cyclosporin-A, and at one week, growth of cancer cells was ceased. 3. The MTT assays were decreased as cyclosporin-A concentration was increased. This means that the activation of succinyl dehydrogenase in mitochondria was decreased following administration of cyclosporin A. 4. A result of RT-PCR showed that amount of mRNA of VDAC-2 was decreased half times at a cyclosporine-A concentration of 2000ng/ml. In bcl-2, amount of mRNA was significantly decreased 1/5 times at 2000ng/ml. caspase-9, however, showed slight increase compared to the control group. From the results obtained in this study, administration of cyclosporin-A to the cell lines of oral squamous cell carcinoma induced alterations in morphology and growth of the cells as its concentration increased. Since apoptosis related factors such as VDAS-2, bcl-2, and caspase-9 also showed distinct alterations on their mRNAs, further research on cyclosporin A as an anti-cancer agent will be feasible.

• Resources Recycling
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• v.15 no.3 s.71
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• pp.46-57
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• 2006

This study was carried out for the purpose of recovering the refined gypsum from waste phosphogypsum. The refined gypsum was recovered as a under product of 325 mesh wet screening followed by dehydration and hydration stage. The influence of dehydration temperature and time, dehydration rate, aging time, slurry density of hydration and sonication time on the yield and grade of gypsum were investigated. The refined gypsum of $94{\sim}96%$ grade is recovered in 95% yield by wet screening after selective dehydration and hydration process, from the phosphogypsum. For the better separation efficiency of gypsum, it is recommended to treat the phosphogypsum at the conditions of as follows; 6hr's dehydration at $140^{\circ}C$, hydration slury density of $3{\sim}10%$, hydration temperature of $20{\sim}30^{\circ}C$, hydration time of 2hr. In additions, addition of sodium citrate 0.005M and sonication of $5{\sim}10min.$ are effective for increase the recovery of gypsum. On the other hand, aging the dehydrated gypsum 16 hours or longer make decrease the recovery of gypsum remarkably.