• Journal of Powder Materials
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• v.29 no.1
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• pp.47-55
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• 2022

Tungsten carbide is widely used in carbide tools. However, its production process generates a significant number of end-of-life products and by-products. Therefore, it is necessary to develop efficient recycling methods and investigate the remanufacturing of tungsten carbide using recycled materials. Herein, we have recovered 99.9% of the tungsten in cemented carbide hard scrap as tungsten oxide via an alkali leaching process. Subsequently, using the recovered tungsten oxide as a starting material, tungsten carbide has been produced by employing a self-propagating high-temperature synthesis (SHS) method. SHS is advantageous as it reduces the reaction time and is energy-efficient. Tungsten carbide with a carbon content of 6.18 wt % and a particle size of 116 nm has been successfully synthesized by optimizing the SHS process parameters, pulverization, and mixing. In this study, a series of processes for the high-efficiency recycling and quality improvement of tungsten-based materials have been developed.

• Resources Recycling
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• v.32 no.2
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• pp.12-18
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• 2023

In 2018, the demand for silver (referred to as Ag) in the electrical and electronics sector was 249 million tons. The demand stood at 81 million tons in the solar module production sector. Currently, due to the rapid increase in solar module installation, the demand for silver is increasing drastically in Korea. However, Korea's natural metal resources and reserves are insufficient in comparison to their consumption, and the domestic silver ore self-sufficiency rate was as low as 2.2% as of 2021. This implies that a recycling technology is necessary to recover valuable metal resources contained in the waste plating solution generated in the metal industry. Therefore, this study compared and analyzed, the results of the impact evaluation through life cycle assessment according to an improvement in the process of recovery of valuable metals in the waste plating solution. The process improvement resulted in reducing GWP (Global Warming Potential) and ADP(Abiotic Depletion Potential) by 50% and 67%, respectively. The GWP of electricity and industrial water was reduced by 98% and 93%, respectively, which significantly contributed to the minimization of energy and water consumption. Thus, the improvement in recycling technology has a high potential to reduce chemical and energy use and improve resource productivity in the urban mining industry.

• Korean Journal of Social Welfare
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• v.35
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• pp.31-50
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• 1998

The purpose of this study to provide implications for improvement of Korean voluntary sector, by analyzing of program managers' subjective evaluation of voluntary program management and of their view of the needs for outside supports. For this, researchers selected 600 agencies, which are found to have a staff in charge of voluntary programs, and sent a questionnaire by mail. Those agencies are consisted of the following three. areas: social services, civil movement, public sector. The response rate was 65%, and researchers analyzed 382 respondents out of 391, besides those who did not complete the form in full. One of the results was that program managers' subjective evaluation score of overall voluntary program management was 51 points in the perfect score of 100 points. The voluntary program management was consisted of the following six areas: recruiting, job placement, public relations, education(training), program development, and. information system Specifically, program development and information system appeared to be worse than the other areas, and this fact was true in all three types of agencies of social services, civil movements, and public sector. Moreover, program managers in public sector showed that outside supports for voluntary programs (or activities) was more desperately required. Based on the results, researchers concluded that, toward the improvement of voluntary programs, professionalization as well as legal supporting system, networking, and national supporting institution were required.

• Resources Recycling
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• v.32 no.1
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• pp.33-41
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• 2023

Herein, we selectively recovered Zn and produced ZnSO₄ from electric arc furnace dust using a hydrometallurgical process. The analysis of the properties of the electric arc furnace dust revealed that the Fe content (9.9%) was relatively low while the Mn content (19%) was high as compared to the composition of general dust. Therefore, an appropriate hydrometallurgical process was designed based on the properties of the raw materials. In the leaching process involving the use of 1.6 M sulfuric acid and 20% solid-liquid ratio at 60℃ for 1 h, 85% of the Zn and Mn got dissolved while the Fe was not leached. To selectively recover Zn, a solvent extraction process using D2EHPA as the extractant was chosen, and 99% of the Zn was extracted using 0.8 M D2EHPA with 32% saponification and an O/A ratio of 2 using counter-current 3-stage extraction. Mn was entirely scrubbed with an aqueous sulfuric acid solution of pH 1.5. Finally, Zn was concentrated and stripped using 1.5 M sulfuric acid at an O/A ratio of 4 using counter-current 4-stage stripping. The stripping solution contained 40 g/L of Zn, and 99.9% of ZnSO₄∙H₂O was obtained by vacuum distillation.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.73-82
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• 2022

Waste paint, one of the specified wastes in Korea, is currently treated entirely by incineration treatment method, and is hardly recycled compared to other wastes. Incineration treatment method also causes environmental problems such as air pollution. Thus, this study breaks away from the existing incineration treatment method of waste paint and switch to a method of pretreatment operation through evaporation, condensation, and thermal decomposition by temperature control. and then proposes a sustainable waste paint treatment process that can be recycled as an alternative energy heat source. If a new method of disposing of waste paint and technology for recycling are developed and disseminated, it is expected that the effect will be large from an economic and environmental point of view.

• Resources Recycling
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• v.31 no.2
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• pp.33-39
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• 2022

In this study, analytical thermochemical modeling factors that contribute to maintaining a specific temperature range during vanadium roasting as a pretreatment using a rotary kiln are investigated. The model-related mechanisms include thermochemical reaction rates, heat balance, and heat transfer, through which the resultant temperature can be estimated intuitively. Ultimately, by optimizing these parameters, the ideal roasting temperature in the kiln is ≈1000 ℃ (or ≈1273 K) for long-term operation. Therefore, the heat generated from hydrocarbon (natural gas) fuel combustion and ore oxidation reactions, as well as the radiant heat transferred to ores, are assessed. In addition, thermochemical methods for relieving the temperature gradient in order to maintain the optimum temperature range of the rotary kiln are suggested.

• Resources Recycling
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• v.15 no.3 s.71
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• pp.3-19
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• 2006

Sustainable supply of minerals and energy is global problem. Metals and energy consumption in the world has increased with economic growth. Currently more than 40 metals are systematically extracted and used in many different fields in civilized society. Recycling and reuse have become very important because recycling contributes to supplying the materials and protecting the environment of society. It is not realistic that all waste materials are capable of being recycled, because recycling metals have fundamentally been competing with primary production. In this point of view, prior to discuss on current recycling technology of waste resources in Korea, world wide trend and Korean recent activity in the supply-demand far minerals and energy resources are reviewed.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.371-374
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• 2003

본 연구에서는 200kw급 풍력발전 시스템의 설치 지역으로 고려 중인 제주도 봉개동 지역의 풍황을 계측장비를 이용하여 7개월에 걸쳐 조사하였다. 측정된 자료들과 자체 제작 분석 프로그램을 사용하여 설치 예상 지역의 연간 예상 발전량 및 이용률 등과 같은 풍력자원을 분석하였다. 또한, 풍력자원 분석결과를 토대로 시스템의 설치 당위성 및 타당성의 판단기준의 하나인 발전단가 및 투자회수기간을 구하는 경제성 분석을 수행하였다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 1993.03a
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• pp.9.1-10
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• 1993

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.10a
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• pp.276-280
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• 2005