• Journal of computational fluids engineering
• /
• v.20 no.4
• /
• pp.81-92
• /
• 2015

Construction waste mainly consists of concrete aggregates of various size. Improper handling of concrete waste would be a major environmental problem whereas its recycling would be both economically useful and environmentally friendly. Bigger concrete aggregates are crushed and converted to medium and fine particles to make them recyclable. An apparatus to separate the concrete aggregates by their size is thus needed for their effective recycling. In this work, segregation of concrete particles in air flows from a newly designed rotary separator having three stages of blades is simulated using a commercial software, ANSYS-CFX. Both 2-D and 3-D models with 360, 240 and 180 blades in each stage are considered. Fundamental mechanism of separation of particles(pase) and the effect of design parameters such as particle size, rotor speed, air flow rate etc. on the performance of the separator are investigated. Critical size of particles that can be separated by the developed separator is also presented in this work. Simulation results are overall in good agreement with data predicted from the theoretical model previously reported in the companion paper.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.5
• /
• pp.59-67
• /
• 2012

During the manufacturing of Portland cement, CO2 gas is also necessarily produced through both decarbonation of calcium carbonate and kiln burning. By partially replacing the Portland cement with limestone powder, which is an inert filler in a concrete mixture, CO2 consumption can be reduced in a construction field. This study is to investigate the fundamental durability characteristics of limestone powder added concrete. Experimental variable was the replacement ratio of limestone powder from 0% to 25% with 5% increment. Durability characteristics were investigated by resistance to freeze-thaw, alkali-silica reaction and de-icing chemical in addition to the properties of fresh concrete. From test results, it was observed that the addition of limestone powder did not significantly affect the resistance to freeze-thaw reaction and de-icing chemical. The addition of limestone powder reduced the occurrence potential of alkali-silica reaction by reducing an alkali content in Portland cement.

• Journal of the Korea Concrete Institute
• /
• v.22 no.6
• /
• pp.787-796
• /
• 2010

The main reason of the earth global warming is $CO_2$ and the regulation about it in the whole world has been reinforced to reduce $CO_2$ emission. It is needed that we should reduce it in the process at the production of concrete generated much of $CO_2$ emission as the primary material of construction industry recognized unfriendly environment industry. Based on a concrete, this study was constructed the system to evaluate $CO_2$ emission generated in the stage of material production, transportation, manufacture and developed the program to reduce and evaluate it efficiently. As a result, most of $CO_2$ emission is generated in the stage of material and it is quantitatively evaluated $CO_2$ emission generated in the stage of materials, transportation and manufacture. Moreover, the evaluation system of the volume of $CO_2$ emission which has the friendly environment technology about reduction of $CO_2$ emission at each stage is suggested for quantitatively evaluation $CO_2$ emission generated in the process at the production of concrete and remicon production company could use it to evaluation $CO_2$ emission.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.11 no.1
• /
• pp.50-54
• /
• 2008

There are several basic classes of recycling methods for FRP boats. The main one is 'Mechanical recycling' which involves shredding and grinding of the scrap FRP in a new product. That is one of the simpler and more technically proven methods. It recently has been reported that FRP can be recycled by separating into layers instead of crushing into powder. Many researchers should be more interested in these mechanical recycling for the eligibility. Nevertheless, because resins is very useful renewable energy, most of waste FRP regenerating methods depend on incineration (reclamation) or thermal recycling (pyrolysis). FRP is made up of laminated glass- fiber (roving cloth layer) which is also very unlikely to break into each layer. If there is an extracting method which is efficient and environment friendly removing glass fiber from waste FRP, it should also solve the another urgent problem. Laminated glass-fiber which is very limited renewable, is a serious barrier to wast FRP boat regenerating. This study is to propose a new extracting method which is efficient and environment friendly waste FRP regenerating system. And it should be applied to renewable energy applications with the waste resins of FRP. Also recycling glass fiber obtained by the separation of the roving layer from waste FRP will be consider to be useful for concrete products or structures.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.880-894
• /
• 2010

The Grout injected precast pile is widely used in rapid-transit railway bridge recently. The existing portland cement of well used filling at injected precast method that with low strength and environmental pollution, unstable in which ground water contamination by cement flow out, ground relaxation by water down, decrease of horizontality resistance and durability and load transfer divide etc. In particular, as in rapid-transit railway bridge need to secure safety from different angle with vibration of high speed train, horizontal force when train stop and earthquake. Works of foundation construction consider to requirements of the times to coal yard green growth. Together, new green foundation method for possible economics and securing of reduce the term of works are material to developments. Therefore, we carried out study that it is using and development new concept environment - friendly filling include durability and earthquake resistance, for secure safety and minimize environment pollution. To achieve this, we carried out difference tests that new green fillings of underwater concrete, high liquidity, high viscosity, early stiffness as compared to existing portland cement fillings. As results, new green filling have outstanding application at precast pile method and micropile construction method with vertical bearing capacity, horizontal bearing capacity and many case. From now on we will be looking forward to development of new environment-friendly foundation method from various further studies.

• Structural Engineering and Mechanics
• /
• v.47 no.5
• /
• pp.679-700
• /
• 2013

Two new predictive design methods are presented in this study. The first is a hybrid method, called neuro-fuzzy, based on neural networks with fuzzy learning. A total of 280 experimental datasets obtained from the literature concerning concentric punching shear tests of reinforced concrete slab-column connections without shear reinforcement were used to test the model (194 for experimentation and 86 for validation) and were endorsed by statistical validation criteria. The punching shear strength predicted by the neuro-fuzzy model was compared with those predicted by current models of punching shear, widely used in the design practice, such as ACI 318-08, SIA262 and CBA93. The neuro-fuzzy model showed high predictive accuracy of resistance to punching according to all of the relevant codes. A second, more user-friendly design method is presented based on a predictive linear regression model that supports all the geometric and material parameters involved in predicting punching shear. Despite its simplicity, this formulation showed accuracy equivalent to that of the neuro-fuzzy model.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.6
• /
• pp.83-90
• /
• 2018

This paper introduces a innovative diamond wire saw cutting technology and its experimental verification that can be utilized for cutting heavy structures. While conventional diamond wire saw cutting technologies such as water cooled cutting method and dry cutting method cause severe environmental problems due to generating massive concrete sludge or dust scattering, the proposed method can eliminate those problems considerably. Through extensive experiments using heavy structure test bed and real bridge pier structure, comprehensive analysis and comparative evaluation about various cutting methods were performed. As a result, the innovative diamond wire saw cutting method could achieve a similar cutting and cooling performance to the water cooled cutting method without generating concrete sludge and it showed an improved cutting and cooling performance to the dry cutting method without dust scattering. Consequently it is confirmed that the suggested cutting technology can be a promising environment-friendly alternative in the field of heavy structure dismantling.

• Journal of Navigation and Port Research
• /
• v.28 no.1
• /
• pp.105-111
• /
• 2004

This study is aiming at examining the possibilities to develop eco-friendly waterfront, and discusses characteristics of the organic worldview which has been emerged as new development or eco-friendly paradigm in recent science against the mechanical worldview of modem times. The orientation of waterfront development is characterized as unity, diversity, dynamics and mutuality. In addition, I examined the factors for waterfront design according to the locational, decorativeand visual properties of urban$.$architecture to find out concrete factors of its design. This study suggests the factors for waterfront design making use of organic properties, by examining the orientation for organic development of eco-friendly waterside environment and showing correlation between the factors of specific design, and their examples.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.5
• /
• pp.29-36
• /
• 2008

The shotcrete is a NATM technique as a major tunnel support for ground stability after tunnel excavation. Instead of a general concrete lining method, it is a trend for curtail of construction periods and reduction of construction expenses that required to use of the permanent shotcrete lining. This high-strength shotcrete is required to use as a permanent shotcrete lining. This brought out the solution of environmental pollution and harmfulness to human. Accordingly, in this study specimens for strength measurement were made to develop shotcrete possible to develop materials in early with cement mineral accelerator as NATM method construction. It was compared with existing shotcrete material, unconfined compression test, flexural strength test, antiwashout underwater test were experimented. The fish poison test was experimented to evaluate an influence of environment. As a results of the test, unconfined compressive strength and flexural strength were equivalent with 28-curing day strength of existing material. An antiwashout of research subject material was revealed excellently in antiwashout Underwater test. As a results of the fish poison, an evaluation research subject material was founded more environmentally friendly than existing shotcrete.

• The Journal of the Korea Contents Association
• /
• v.12 no.3
• /
• pp.449-460
• /
• 2012

Since 1970's, the rivers in industrial cities and metropolitan cities in Korea have been severely contaminated and the riverfronts have been to garbage yard, warehouses and sanitary facilities that produce low efficiency in urban land-use. As a result, riverfront in most cities became lost space and artificial area which composed of asphalt road, concrete riverbank and parking lot. However, Sustainable management is the main concept of riverfront development in 21st century. Also, in contemporary riverfront space, it is the pivotal paradigm that the development of eco-space and mixture of cultural space. Citizen require greener, more ecological and water-friendly space in riverfront of city. So, the purpose of this paper lies in suggestion for building sustainable development and management for riverfront in Korean city. For this purpose, this paper has reviewed the developmental trend of recent riverfront, has analyzed locational environment and land use of riverfront in city, has set policy and the strategy for sustainable riverfront.