• Journal of the Korean Society for Marine Environment & Energy
• /
• v.10 no.2
• /
• pp.102-106
• /
• 2007

While the effort has been made in recycling the FRP (Fiber Reinforced Plastic) used for the medium-to-small size ships, researchers try to find out the methods more favorable for the environments and more value-added. In respect to the fact that the FRP consists of two types of layers, roving and mat, differentiated by the 2-dimensional structure, our group was able to separate the layers of FRP instead of grinding it. The roving cloth was cut to the long glass fibers (about 50 mm long; calling it 'F-fiber' afterwards). F-fiber showed increasing tensile strength and chemical-resistance possibly due to the remained resin (about 25% by weight). In this experiment fiber-reinforced mortars are made of the F-fiber as a recycling method of FRP. The mortar containing 2% (v/v) F-fiber results in 34.6% increment of bending strength from the standard after 28 day curing. The resulting strength is similar to that of the mortar with imported polyvinyl fiber P-54. These results imply that F-fiber can be applied to the 'fiber reinforced mortar' and furthermore may be a substitute for the imported fibers.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.26 no.5
• /
• pp.416-422
• /
• 2016

Lots of plastics are widely used in a variety of industrial field. And the amount of plastic waste is massively produced. In the study of waste recycling, it is emerged as an important issue to prevent the waste of potentially useful resource materials as well as to reduce ecological damage. So, the recycling of plastic waste has been currently paid attention to from the view point of reuse. Existing automatic sorting system consist of near infrared ray (NIR) sensors to classify the types of plastics. But the classification of black plastics still remains a challenge. Black plastics which contains carbon black are not almost classified by NIR because of the characteristic of the light absorption of black plastics. This study is focused on handling how to identify black plastics instead of NIR. Raman spectroscopy is used to get qualitative as well as quantitative analysis of black plastics. In order to improve the performance of identification, Support Vector Machine(SVM) classifier and Principal Component Analysis(PCA) are exploited to more preferably classify some kinds of the black plastics, and to analyze the characteristic of each data.

• Resources Recycling
• /
• v.17 no.2
• /
• pp.46-54
• /
• 2008

It is well known that PCB (Printed Circuit Board) is a complex mixture of various metals. In this study, pyro-metallurgical process was investigated to extract valuable metallic components from the PCB scrap. PCB scrap was shredded and oxidized to remove plastic materials, and then, quantitative analysis were made. 15 mass %$Al_2O_3-45$ mass %CaO-40 mass %$SiO_2$ and 32 mass %$SiO_2-20$ mass %$Al_2O_3-38$ mass %CaO-10 mass %MgO, were chosen as basic slag compositions which are determined based on the quantitative analysis of PCB scrap. During experiments a super kanthal rotating furnace was used to melt and separate metallic components. Moreover the revolution effect on was the recovery of valuable metals from PCB scrap also investigated.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.3
• /
• pp.1-6
• /
• 2013

This study has focused on transparency recovering of the polycarbonate by polishing its surface for recycling. The polycarbonate has many properties such as excellent mechanical strength, electrical insulating, superior heat resistance to other plastic material and especially good transparency. It has been used as barrier for the traffic noise at the roadside and the greenhouse for the palm house. But the polycarbonate has changed slightly as time goes by 10 years because of exposure to the strong sunlight and oxidization in the atmosphere, as result has lost its transparency. Magnetic assisted polishing has been utilized as an effective polishing method to recover the transparency of polycarbonate. The polycarbonate which has been used for 10 years was adopted as the sample. The first surface roughness of the sample was 1$1.23{\mu}mRa$, $7.5{\mu}mRz(DIN)$ respectively. In the experimental results, it showed that the surface roughness of the polished sample improved $0.013{\mu}mRa$, $0.08{\mu}mRz(DIN)$ from the first surface roughness respectively. The surface roughness get almost back again by magnetic assisted polishing. These results also showed that the magnetic assisted polishing was efficient machining method to reuse the polycarbonate material.

• Resources Recycling
• /
• v.28 no.2
• /
• pp.23-30
• /
• 2019

An color sorting technique was introduced to recycle End-of-life automobile shredded bumpers. The color sorting is a innovate method of separating the differences in the color of materials which are difficult to separate in gravity and size classification by using a camera and an image process technique. Experiments were planned and optimal conditions were derived by applying BBD (Box-Behnken Design) in the reaction surface method. The effects of color sensitivity, feed rate and sample size were analyzed, and a second-order reaction model was obtained based on the analysis of regression and statistical methods and $R^2$ and p-value were 99.56% and < 0.001. Optimum recovery was 94.1% under the conditions of color sensitivity, feed rate and particle size of 32%, 200 kg/h, and 33 mm respectively. The recovery of actual experiment was 93.8%. The experimental data agreed well with the predicted value and confirmed that the model was appropriate.

• Resources Recycling
• /
• v.17 no.4
• /
• pp.47-56
• /
• 2008

The aim of this study is to produce cokes which can be used for the production of ferroalloy, for this purpose, domestic anthracite mixed with plastic was sintered at various condition. The combustion and physical properties of anthracite and plastic, coal separation, and the influence of factors on the strength of coke were investigated. The results of this study are as follows: 1. The three kinds of anthracite from the Samcheok region contained 25 to 30% ash of $100{\mu}m$ over size, and have the caloric value of 5,205 cal/g(TaeAn), 4,893 cal/g(JangSung), 4,873cal/g(KyongDong). 2. The recommendable conditions for heavy-fluid separation of the Samcheok coal are to set the specific gravity of heavy fluid to 2.4 and control the size of coal to $35{\sim}140mesh$. 3. It is concluded that phenolic resin powder, liquefied phenolic resin, SAN, and melamine resin can be used as a binder for the anthracite cokes, from the thermal analysis of various plastics. Especially, the liquefied phenolic resin was considered as the most suitable binder as it would simplify the process.

• KCI Concrete Journal
• /
• v.14 no.1
• /
• pp.23-29
• /
• 2002

Recent construction activities have given rise to civil petitions associated with vibration-induced damages or nuisances. To mitigate unfavorable effects of construction activities, the measures to reduce or isolate from vibration need to be adopted. In this research, a vibration-mitigated concrete, which is one of the active measures for reducing vibration in concrete structures, was investigated. Concrete was mixed with vibration-reducing materials (i.e. latex, rubber power, plastic resin, and polystyrofoam) to reduce vibration and tested to evaluate dynamic material properties and structural characteristics. Normal and high strength concrete specimens with a certain level of damage were also tested for comparisons. In addition, recycling tires and plastic materials were added to produce a vibration-reducing concrete. A total of 32 concrete bars and eight concrete beams were tested to investigate the dynamic material properties and structural characteristics. Wave measurements on concrete bars showed that vibration-mitigated concrete has larger material damping ratio than normal or high strength concrete. Styrofoam turned out to be the most effective vibration-reducing mixture. Flexural vibration tests on eight flexural concrete beams also revealed that material damping ratio of the concrete beams is much smaller than structural damping ratio for all the cases.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.37
• /
• pp.27.1-27.7
• /
• 2015

The aim of this study was to evaluate the clinical relevance of autogenous fresh demineralized tooth (Auto-FDT) prepared at chairside immediately after extraction for socket preservation. Teeth were processed to graft materials in block, chip, or powder types immediately after extraction. Extraction sockets were filled with these materials and dental implants were installed immediately or after a delay. A panoramic radiograph and a conebeam CT were taken. In two cases, tissue samples were taken for histologic examination. Vertical and horizontal maintenance of alveolar sockets showed some variance depending on the Auto-FDT and barrier membrane types used. Radiographs showed good bony healing. Histologic sections showed that it guided good new bone formation and resorption pattern of the Auto-FDT. This case series shows that Auto-FDT prepared at chairside could be a good material for the preservation of extraction sockets. This study will suggest the possibility of recycling autogenous tooth after immediate extraction.

• Computers and Concrete
• /
• v.26 no.1
• /
• pp.11-20
• /
• 2020

Concrete are the most widely used manmade materials for infrastructure construction across the world. These constructions gradually aged and damaged due to long-term use. However, there does not exist an efficient concrete recycling method with low energy consumption. In this study, concrete was regarded as a heterogeneous material composed of coarse aggregate and cement mortar. And the failure mode of concrete under ultrasonic dynamic loading was investigated by finite element (FE) analysis. Simultaneously, a 3D random aggregate concrete model was programmed by APDL and imported into ABAQUS software, and the damage plastic constitutive model was applied to each phase to study the damage law of concrete under dynamic loading. Meanwhile, the dynamic damage process of concrete was numerically simulated, which observed ultrasonic propagating and the concrete crushing behavior. Finally, the FE simulation considering the influence of different aggregate volume and aggregate size was carried out to illustrate the damage level of concrete.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.3
• /
• pp.253-259
• /
• 2021

Plastic wastes generated from household waste are separated by mixed discharge with foreign substances, and recycling is relatively low. In this study, the effect of the ratio and content of mixed plastic waste coarse aggregate(MPWCA)s and mixed plastic waste fine aggregate(MPWFA)s filled with blast furnace slag fine powder on the slump and compressive strength of concrete was evaluated experimentally. The MPWCAs were found to have a similar fineness modulus, but have a single particle size distribution with a smaller particle size compared to coarse aggregates. However, the MPWFAs were found to have a single particle size distribution with a larger fineness modulus and particle size compared to fine aggregates. Meanwhile, the effect of improving the density and filling pores by the blast furnace slag fine power was found to be greater in the MPWFA compared to the MPWCA. As the amount of the mixed plastic waste aggregate(MPWA)s increased, the slump and compressive strength of concrete decreased. In particular, the lower the slump and compressive strength of concrete was found to decrease the greater the amount of MPWFA than MPWCA when the amount of MPWA was the same. This is because of the entrapped air and voids formed under the angular- and ROD-shaped aggregates among the MPWFAs. On the other hand, the addition of the admixture and the increase in the unit amount of cement were found to be effective in improving the compressive strength of the concrete with MPWAs.