• International Journal of Concrete Structures and Materials
• /
• v.6 no.3
• /
• pp.145-153
• /
• 2012

The aim of this study is to explore the possibility of re-cycling a waste material that is now produced in large quantities, while achieving an improvement of the mechanical properties and durability of the mortar. This study examines the mechanical properties and the durability parameters of mortars incorporating plastics bag wastes (PBW) as fine aggregate by substitution of a variable percentage of sand (10, 20, 30 and 40 %). The influence of the PBW on the, compressive and flexural strength, drying shrinkage, fire resistance, sulfuric acid attack and chloride diffusion coefficient of the different mortars, has been investigated and analyzed in comparison to the control mortar. The results showed that the use of PBW enabled to reduce by 18-23 % the compressive strength of mortars containing 10 and 20 % of waste respectively, which remains always close to the reference mortar (made without waste). The replacement of sand by PBW in mortar slows down the penetration of chloride ions, improves the behavior of mortars in acidic medium and improves the sensitivity to cracking. The results of this investigation consolidate the idea of the use of PBW in the field of construction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.1
• /
• pp.176-181
• /
• 2008

This paper was studied the possibility on the recycling of the scrap used as the food packaging materials, PP/EVOH/PP multilayer. Recycling study was investigated into thermal and mechanical properties of samples which were mixed PP/EVOH waste plastics scrap with two kinds of compatibilizers. Melt behaviors as thermal property and tensile strength, % strain at break point, and tensile modulus as mechanical properties were investigated into kinds of and the weight ratio of compatibilizers. Mixed PP/EVOH waste plastics shows compatibity when Minanto-s and GMS as compatibilizers are mixed 0.5wt.% over.

• Journal of Mechanical Science and Technology
• /
• v.16 no.10
• /
• pp.1336-1345
• /
• 2002

A triboelectrostatic separation system using a fluidized bed tribocharger for the removal of PVC material in the mixture of PVC/PS plastics is designed and evaluated as a function of electric field strength, air flow rate, and the mixing ratio of two-component mixed plastics. It consists of a fluidized-bed tribocharger, a separation chamber, a collection chamber and a controller. PVC and PS particles can be imparted negative and positive surface charges, respectively, due to the difference in the work function values of plastics suspended in the fluidized-bed tribocharger, and can be separated by passing them through an external electric field. Experimental results show that separation efficiency is strongly dependent on the electric Deld strength and particle mixing ratio. In the optimum conditions of 150 Ipm air flow rate and 2.6 kV/cm electric field strength a highly concentrated PVC (99.1%) can be recovered with a yield of more than 99.2% from the mixture of PVC and PS materials for a single stage of processing.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1354-1357
• /
• 2003

Mold Analysis is crucial factors in the design of injection molding process. Since the qualify of products depends on filing, shrinkage and etc, the procedure of prediction through analysis in the design of injection molding process is needed. In many cases, this kind of analysis makes it possible to predict pressure pattern which determines the condition of injection molding process. Crystallinity is the factor that determines the shrinkage of products. The studies showed the factors that had been related to the degree of crystallinity, which were mostly Weight Reduction, mold temperature and melt temperature. Therefore, the objective of this study is to see the differences of the degree of crystallinity depending on the positions of foamed plastics. The procedure of this study is as the following. First, Simulate the pressure gradient in mold cavity that can produces specimen by using Moldflow. Secondly, produce specimen and measure the degree or crystallinity of each part of specimen by using XRD. Lastly, identify the sensitivity of conventional plastic and foamed plastic on pressure gradient by comparing the simulation and the results of measurement.

• International journal of advanced smart convergence
• /
• v.9 no.1
• /
• pp.70-81
• /
• 2020

Plastics that we use and simply throw away have a life span of about 500 years and barely decompose. The practice of producing and using common plastics needs to be challenged. Until now, they have been useful in the industrial structure of mass production, but it can be said that there is a lack of research into new materials to introduce and apply in terms of material recycling. As a result of this, we have come to the uncomfortable realization of the fact that we cannot incinerate or reuse these precious resources indiscriminately. No matter how well-designed a product is, it has a competitive advantage if production and consumption activities, waste, collection, sorting and treatment are considered in terms of a continuous cycle, and in this respect, Extended Producer Responsibility (EPR) can help. We are implementing the EPR system, and active industrialization in the field of recycling is required, which is also a challenge for producers to participate actively in recycling and seek to save and recycle resources in design and manufacturing. Against this backdrop, We would like to examine the possibilities, through various studies and developments on product design of recyclable materials, which is being conducted mainly in Europe. In particular, we would like to examine the methods, and value of solving environmental problems and the active efforts to achieve this in the design world, and in particular the case of product design using recycled plastics.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.6
• /
• pp.42-49
• /
• 2009

The optical elements made of plastics are normally produced by mass production such as injection molding with use of precision dies and molds. It costs to prepare the dies and molds, and it is only justified to prepare such expensive dies and molds when the parts are massively produced. On the other hand, it is too expensive and inefficient when precision plastic parts are needed only in small quantities, such as a case of trial manufacturing of new products. An ultra-precision diamond cutting is one of promising processes to produce the precision plastic parts in such cases. But it is commonly believed that an ultra-precision cutting of plastics for optical components is very difficult, because they are thermo-plastic material. In the present research, an ultra-precision diamond cutting of polycarbonate (PC), that is one of typical optical materials, was tried by using elliptical vibration cutting method. It is experimentally proved that good optical surfaces were obtained by using elliptical vibration cutting in cases of grooving and flat surfaces. The maximum surface roughness of less than 60 nm in peak to valley value is acquired.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.10
• /
• pp.2514-2522
• /
• 1994

The mirror surface grinding of carbon fiber reinforced plastics(CFRP) was realized by using the metal bonded super-abrasive micro grain wheel with electrolytic in-process dressing(ELID). The maximum surface roughness $R_{max}$ of CFRP which was obtained with #6,000 wheel, was 0.65 $\mu{m}$, which was rougher surface finish compared to those of hard and brittle materials with the same mesh number wheel with ELID. The grinding performance was much dependent on the grinding direction and the best surface roughness was obtained at $90^{\circ}C$ grinding with fiber direction. The spark-out effect on the surface improvement was significant when smaller mesh number grinding wheels were used. From the surface observations of CFRP with scanning electron microscope(SEM) and Auger electron spectroscopy(AES), it was found that the mirror surface grinding of CFRP was generated by the homogenization due to carbonization of the ground surface and smearing of chips composed of the carbon fiber and carbonized epoxy resin into the ground surface.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.4
• /
• pp.101-111
• /
• 1998

This study presents test results of RC beams strengthened by carbon fiber sheet(CFS), carbon fiber reinforced plastics(CFRP) or glass fiber reinforced plastics(GFRP) for increasing shear resistance. Nineteen specimens were tested, and the test was performed with different parameters including the type of strengthening materials(CFS, GFRP, CFRP), shear-strengthening methods(wing type, jacket type, strip type), strip-spacing, strengthening direction of FRP. The test results show that shear-damaged RC beams strengthened by FRP(CFS, GFRP, CFRP) have more improved the shear capacity. The mathematical model based on plastic theory was also developed to predict shear strength of shear-damaged RC beams strengthened by FRP. The predictions using the mathematical model. are agreed with the observations from the observed shear strengths for 19 test beams.

• Resources Recycling
• /
• v.11 no.3
• /
• pp.37-45
• /
• 2002

Triboelectrostatic Separation procese is a technology that different particles charged after contact and rubbing different materials are separated in an electric field. At this time, charged polarity of different materials depends on their own work function. Therefore this study discovers work functions of various plastics and determines charging characteristics for the specific optimum operation condition. The experiment is conducted with two sample sets composed of various different plastics. Each sample is charged by contact and rubbing different materials. Surface charge of charged particles is measured by Faraday Cage. The specific work function of an each plastic is driven by measured charging amount and charged particles are separated in a certain electric field ($\pm$20 kV). At last, the relationship between charging amount and separation efficiency is induced by the separation experiment.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.8 s.185
• /
• pp.195-202
• /
• 2006

High-speed machining (HSM) with excellent quality and dimensional accuracy has been widely used to create 3D structures of metal and plastics. However, the high-speed machining process is not suitable for the rapid realization of 3D thin-walled product because it consumes considerably long time in fixturing process of a work piece. In this paper, an effective rapid manufacturing process is proposed to fabricate 3D thin-walled products directly using HSM, phase change filling and ultrasonic welding. The filling process is useful to hold the thin-walled product during the machining step. The ultrasonic welding process is introduced to make one piece product from two piece parts that are machined by HSM and filling process. The proposed rapid manufacturing (RM) process has been shown that the RM process enables to fabricate the 3D thin-walled products using ABS plastics and aluminum metals from 3D CAD data to functional parts.