• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.69-72
• /
• 2005

Recently, there have been many studies seeking towards the utilization of cementitious powder from concrete waste as recycle cement. However, most of the studies actually have been researches about the reuse of mortar or paste, not concrete waste. In fact, either mortar or paste is quite different from a real concrete waste in terms of age and mixture. Thus the purpose of this study is to examine basic physical properties of recycle cement, manufactured with cementitious powder from concrete waste, and analyze differences in chemical and hydraulic properties of the cement and its tested model. As a result of the chemicai analysis, recycle cement is composed mainly of CaO and SiO2, and that it is even lower in the content of CaO than Portland cement, which is also supported by previous studies. But, Differently from previous studies, plastic working at the temperature of 650 was found an optimal condition under which cementitious powder from concrete waste could restore its hydraulic properties.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.23 no.2
• /
• pp.21-27
• /
• 2015

An introduction of landfill tax has been recently in issue in order to raise the financial resource for establishing waste resource-circulation society. The objectives of this study are to evaluate the plan of increasing energy recovery from waste at Incheon Metropolitan City, and to propose several points to be considered in terms of introducing the landfill tax. There are a lot of problems that impede energy recovery from waste at Incheon Metropolitan City, such as high-calorific waste from decrease of food waste to the municipal incineration plant, metals and batteries in the standard plastic garbage bag, etc. Alternative policies to solve these major problems have been drawn.

• Proceedings of the IEEK Conference
• /
• 2001.10a
• /
• pp.751-754
• /
• 2001

A possibility of using waste plastics as a source of secondary fuel in blast furnace has been of recent interest. The success of this process, however, will be critically dependent upon the optimization of operating systems. for instance, the supply of waste plastics must be reliable as well as economically attractive compared with conventional secondary fuels such as heavy oil, natural gas and pulverized coal. In this work, we put special importance on the improvement of the combustibility of waste plastics as a way to enhance energy efficiency in blast furnace. As experimental variables to approach this target, the effects of plastic particle size, blast temperature, and the level of oxygen enrichment were investigated using a custom-made blast model designed to simulate a real furnace. Lastly, the combustion efficiency of the mixture of waste plastics and pulverized coal was tested. The observations made from these experiments led us to the conclusion that with the increase of both blast temperature and the level of oxygen enrichment, and with the decrease of particle size, the combustibility of waste PE could be improved at a given distance from tuyere. Also it was found that the efficiency of coal combustion decreased with the addition of plastics; however, the combustion efficiency of mixture could be comparable at longer distance from tuyere.

• International Journal of Computer Science & Network Security
• /
• v.21 no.8
• /
• pp.65-70
• /
• 2021

Waste accumulation is becoming a significant challenge in most urban areas and if it continues unchecked, is poised to have severe repercussions on our environment and health. The massive industrialisation in our cities has been followed by a commensurate waste creation that has become a bottleneck for even waste management systems. While recycling is a viable solution for waste management, it can be daunting to classify waste material for recycling accurately. In this study, transfer learning models were proposed to automatically classify wastes based on six materials (cardboard, glass, metal, paper, plastic, and trash). The tested pre-trained models were ResNet50, VGG16, InceptionV3, and Xception. Data augmentation was done using a Generative Adversarial Network (GAN) with various image generation percentages. It was found that models based on Xception and VGG16 were more robust. In contrast, models based on ResNet50 and InceptionV3 were sensitive to the added machine-generated images as the accuracy degrades significantly compared to training with no artificial data.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.11a
• /
• pp.341-342
• /
• 2000

산업사회를 발전시키는데 있어서 큰 기여를 하여온 플라스틱(Plastic)은 사용의 편리성과 다양한 형태로의 제품의 증가, 최근 자동차수의 급격한 증가, 그리고 석유화학공업의 발달로 폐플라스틱류의 발생빈도와 함유량이 급증하고 있다. 일반적으로 널리 사용되어 지고 있는 플라스틱의 종류는 7대 범용수지로 분류되는 LDPE, HDPE, PP, PS, PVC, ABS, PET가 전체 플라스틱 생산의 대부분을 차지하고 있다. (중략)

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.222-223
• /
• 2017

In the automotive industry, such as scrap metal and plastic scrap process is being recycled. Although the glass beads are used as road paving or other additives and processing crushing, recycling is known that there are limits. The utilization of waste glass was evaluated as a concrete admixture by using powder characteristics and chemical composition of the glass. As a result of using waste-glass powder as an admixture, it is difficult to expect the pozzolanic effect, but it is found that it can increase the fluidity of concrete and ensure the durability performance in the appropriate amount range.

• Journal of Ecology and Environment
• /
• v.44 no.1
• /
• pp.45-53
• /
• 2020

Background: The black soldier fly (Hermetia illucens) is gaining attention as an efficient decomposer of food waste. However, recalcitrant compounds such as plastics mixed into food waste may have negative effects on its growth and survival. Moreover, its efficiency of food waste degradation may also be affected by plastics. In addition, salt (NaCl) can also be present in high concentrations, which also reduces the efficiency of H. illucens-mediated food waste treatment. In this study, we assessed the growth of black soldier fly larvae (BSFL) reared on food waste containing polyethylene (PE) and polystyrene (PS) and NaCl. The weight of BSFL was measured every 2-4 days. Survival and substrate reduction rates and pupation ratio were determined at the end of the experiment. Results: The total larval weight of Hermetia illucens reared on food waste containing PS was greater than that of the control on days 20 and 24. However, the survival rate was lower in the group treated with 5% PS, as was substrate reduction in all PS-treated groups. The weight of BSFL reared on food waste containing PE was lower than that of the control on day 6. PE in food waste did not affect the survival rate, but the pupation ratio increased and substrate consumption decreased with increasing PE concentrations. Regardless of the plastic type, the addition of NaCl resulted in decreased larval weight and pupation ratio. Conclusions: Larval growth of black soldier fly was inhibited not by plastics but by substrate salinity. Additional safety assessments of larvae reared on food waste containing impurities are needed to enable wider application of BSFL in vermicomposting.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.10 no.1
• /
• pp.109-119
• /
• 2002

This study is to estimate that food waste bags with biodegradable plastic are really decomposed by microorganism in composting with food waste and to examinate how biodegradable plastic affects composting. 6 kinds of 30%, 4 kinds of 100% and 2 kinds of none biodegradable plastics were used in d1is study. In 30% biodegradable plastics the highest Degradation rare is 6% in meso-condition and 10% in thermal-condition. Srain at auto break decreased to 150% in meso-condition and 120% in thermal-condition. Stress at max load were also reduced to $180kgf/cm^2$ in mesocondition and $200kgf/cm^2$ in thermal-condition. Usually, LLDPE decreased larger than HDPE in physical characreristics but HDPE is higher in degradation rate. 1n stain at auto break and stress ar max load 100% biodegradable plastic declined to 230% and to $380kgf/cm^2$ in meso-condition and to 440% and to $400/cm^2$ in thermal-condition respectively. 100% biodegradable plastics showed higher biodegradation and decomposition then 30%. They appeared clearly through SEM observation. As a result, it was not appropriate to use 30% biodegradable plastics as food waste bag because they were not decomposed perfectly. It is possible to use 100% biodegradable plastic as it but cost is too high. So development of technique is needed.

• Archives of Plastic Surgery
• /
• v.39 no.3
• /
• pp.238-243
• /
• 2012

Background : The publication rate of presentations at medical international meetings has ranged from 11% to 78% with an average of 45%. To date, there are no studies about the final rate of publications at scientific meetings associated with plastic surgery from Korea. The present authors investigated the publication rate among the presentations at meetings associated with plastic surgery. Methods : The titles and authors of the abstracts from oral and poster presentations were collected from the program books of the Congress of the Korean Society of Plastic and Reconstructive Surgeons (CKSPRS) for 2005 to 2007 (58th-63rd). All of the abstracts presented were searched for using PubMed, KoreaMed, KMbase, and Google Scholar. The titles, key words from the titles, and the authors' names were then entered in database programs. The parameters reviewed included the publication rate, type of presentation including running time, affiliation, subspecialty, time to publication, and publication journal. Results : A total of 1,176 abstracts presented at the CKSPRS from 2005 to 2007 were evaluated. 38.7% of the abstracts, of which oral presentations accounted for 41.0% and poster presentations 34.8%, were published as full papers. The mean time to publication was 15.04 months. Among journals of publication, the Journal of the Korean Society of Plastic and Reconstructive Surgeons was most used. Conclusions : Brilliant ideas and innovative approaches are being discussed at CKSPRS. The 38.7% publication rate found from this research appeared a bit lower than the average rate of medical meetings. If these valuable presentations are not available as full papers, the research would be a waste of time and effort.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.12 no.4
• /
• pp.85-94
• /
• 2004

Waste wood-plastic composite panels are made on different hot press molding conditions, and tested for apparent density, water absorption, expansion in thickness and flexural strength. From the test results, regardless of molding temperature and molding time, the apparent density of the composite panels is increased with an increase in the molding pressure, while their water absorption is decreased with an increase in the molding pressure. The flexural strength of the composite panels is markedly increased with increasing molding pressure, molding temperature and molding time, and tends to become nearly constant at a molding temperature of $120^{\circ}C$ and a molding time of 15min.