• Tunnel and Underground Space
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• v.15 no.4 s.57
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• pp.264-274
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• 2005

The optimum blasting pattern to excavate a quarry efficiently and economically can be determined based on the minimum production cost which is generally estimated according to rock fragmentation. Therefore it is a critical problem to predict fragment size distribution of blasted rocks over an entire quarry. By comparing various prediction models, it can be ascertained that the result obtained from Kuz-Ram model relatively coincides with that of field measurements. Kuz-Ram model uses the concept of rock factor to signify conditions of rock mass such as block size, rock jointing, strength and others. For the evaluation of total production cost, it is imperative to estimate 3-D spatial distribution of rock factor for the entire quarry. In this study, a sequential indicator simulation technique is adopted for estimation of spatial distribution of rock factor due to its higher reproducibility of spatial variability and distribution models than Kriging methods. Further, this can reduce the uncertainty of predictor using distribution information of sample data The entire quarry is classified into three types of rock mass and optimum blasting pattern is proposed for each type based on 3-D spatial distribution of rock factor. In addition, plane maps of rock factor distribution for each ground levels is provided to estimate production costs for each process and to make a plan for an optimum blasting pattern.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.167-172
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• 2007

Since 1990s, these many researchers have been fully involved in developing recycling methods for FRP boats. There are four basic classes of recycling covered in the literature. the first is "Mechanical recycling" which involves shredding and grinding of the scrap FRP in a new product. Despite of the safety hazards, mechanical recycling is one of the simpler and more technically proven methods. Recent researchers should be more interested in these methods. It is fact that most of FRP wastes are depended on incineration or reclamation. Because it Is made up of reinforced fiber glass, it is very difficult to break into pieces. By the disposing of waste FRP this way, it also occurs secondary problem such as air pollution and unacceptable noise. This study is to propose a new method which is efficient and environment friendly waste FRP regenerating.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.05a
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• pp.463-466
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• 2002

건설현장의 특성상 굴착공사는 필수공정이고 비록 말뚝공사가 없다할지라도 암반굴착 등 진동소음 발생여지는 언제나 존재하고 있다고 할 수 있다 이에 대한 국부적인 암반발파, 파쇄에 따른 소음감소 또한 큰 문제를 야기할 수 있다. 건설현장 자체적으로 민원 발생에 대비하여 인접 주택 지점에서 소음 계측을 하고 허용값 초과 여부를 판단하는 실행을 하고 있으나 주민이 느끼는 체감 소음은 조금 다를 수도 있어서 민사소송으로까지 확대되어 현장경영 및 공정에 큰 타격을 가하고 회사 이미지 실추로까지 이어질 수 있고 막대한 보상비 지급이 뒤따를 수도 있는 상태로까지 확대될 수 있다.(중략)

• Clean Technology
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• v.25 no.4
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• pp.289-295
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• 2019

Though the usage of vinyls and plastics produced from fossil fuels has been increasing in the world, the eco-friendly domestic disposal or recycling of waste vinyls has to be executed because the migration or importation of waste vinyls or waste plastics are globally prohibited. Even though the eco-friendly domestic disposal or recycling of waste vinyls and waste plastics should be developed, promising eco-friendly recycling methods are few because there are extraneous substances in waste vinyls and waste plastics. Also, conventional incineration and landfill methods result in secondary contamination and then increase disposal costs. Therefore, the selective elimination of extraneous substances or other materials included in waste vinyls and waste plastics could make valuable recycling or reuse possible. In particular, the novel hybrid process in which crushing and screening are simultaneously conducted in a rotary kiln type reactor can domestically maximize the material recycling or reuse. In this study, the feasibility study for a crushing/screening hybrid process developed in Korea was performed and evaluated in case of thermal recycling (TR) and material recycling (MR). The effect of various subsidies on economic efficiency was especially evaluated by means of domestic recycling plans. The incentive revenues from waste vinyl recycling and the incineration share of waste vinyls affected the net present values and internal rate of returns of the hybrid process.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.48-55
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• 2006

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.119-122
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• 2004

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.426-434
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• 2009

This study was carried out to derive the most optimal production process for the wood fuels(chip and pellet), by collecting cost data on each procedure through the life cycle assessment approach, and to compare between the profitability and efficiency, from the view points of producers and consumers, irrespectively. The costs accounted in this analysis were based on the opportunity cost. The results show that wood chips are cheaper than wood pellets in production costs. In respect to the process with the lowest production cost, while wood chips should be to crush collected residues into pieces on the spot for merchandizing, wood pellets need to be transported to manufactory for pelletizing. The study findings also include that the profits, which is estimated by subtracting expenses from gained sale revenue, were a bit higher for wood chips than wood pellets. Additionally, the price ratio of wood pellets to wood chips for getting the same caloric value appears to be 1.27. Despite of economic benefits of processing wood chips, there are several problems in practice. For producers, there is a possible increase in not only transportation cost for conveying crushers to the dispersed places, but storage cost due to the lack of the marketplaces in the immediate surroundings. For consumers, on the other hand, there are some challenging issues, such as bulky storage facility requirement, additional labor for fuel supplement, frequent ashes disposal, and decomposition in summer and freezing in winter caused by wood chips' own moisture.

• Resources Recycling
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• v.25 no.2
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• pp.17-24
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• 2016

This study aims at evaluating environmental impacts on recycling process of used small household appliances. The recycling process mainly consists of manual dismantling, crushing and various sorting processes to effectively recover valuable resources and to minimize environmental impact. In this study, life-cycle assessment (LCA) methodology is applied to analyze major environmental parameters such as GWP, ADP, POCP, EP, etc. One of the major impact categories on the weight basis in the recycling process is global warming (GWP) 57.1%, next to ADP 35.4% and POCP 4.8%, respectively. As a result of environmental impact on recovery of valuable resources/ton, the GWP of plastics for ABS is highest (33.7%) compared to ferrous metals (9.4%). The effects of environmental and economical benefit are also analyzed to compare with the amount of virgin materials to be recycled by recycled materials. In addition, recycled materials are also more economical in comparison to virgin materials due to the environmental avoiding effect by recycling. In conclusion, the key environmental issues related to the recycling of e-wastes are analyzed and therefore, the effective recycling process will contribute to mitigate global warming potential in the near future.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.177-184
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• 2024

This study was conducted to find a way to reduce the production of cakes generated in the domestic aggregate production process. Cakes from 8 wet aggregate producers were collected and particle size was analyzed. Samples were collected step by step from an aggregate producer A, particle size analysis was performed, and the material balance was calculated before and after an sand recovery unit by modeling the production process. As a result of the particle size analysis of eight cakes, one sample contained 50% sand, and the rest contained about 5% to 25% sand. The results showing that the cake contained a variety of sand in cakes may indicate that the recovery efficiency of the sand recovery units in the field varied. Sieve analysis of the samples showed that the generation of sand particles increased 2.8 times during the third crushing compared to the second crushing, and more cake particles were generated. As a result of simulating the sand recovery unit model, the lower the cut point of the cyclone and dewatering screen, the higher the sand production and the less cake production appeared. In order to reduce the production of cake in the field, it was determined that an optimal operation of the sand recovery unit was necessary in the aggregate production process.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.77-84
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• 2005

Amount of demolished concretes is highly produced as dismantlement of structures to increased owing to usage alteration and deteriorated of concrete structures, but most of them have been used as material for simple reclamation. Therefore, if demolished concrete could be recycled as aggregate for concrete. it will contribute to solve the exhaustion of nature aggregate, in terms of saving resources and protecting environment, especially being want of resources in Korea. In this study it was investigated into experimental results that were carried out demolished concrete recycled aggregate gained from dismantled real structures and source concrete recycled aggregate produced according to respectively 5 steps of replacement ratio for recycling as pavement concrete aggregate.