• Clean Technology
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• v.29 no.3
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• pp.172-177
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• 2023

Many studies have been conducted on the indiscriminate use of plastic due to the environment problems it has caused all over the world. This problem can be mitigated by using eco-friendly/biodegradable plastics that can be decomposed by microorganisms or enzymes. This study focused on addressing the plastic golf tees that are thrown away at golf courses. In order to replace conventional golf tees (ABS) with a more eco-friendly alternative, this study explored a biodegradable plastic and 3D printing method for producing golf tees. Among the biodegradable plastics, PLA (polylactic acid) was found to be a good candidate as an eco-friendly material because it is biodegradable by microorganisms. Thus, golf tees were prepared by using PLA via 3D printing, and the physical and chemical properties of the tees were evaluated. The amorphous region of PLA was confirmed through XRD. Also, FT-IR showed the unique peak of PLA without impurities. It was confirmed through an optical microscope that the specific surface area and roughness had increased. This structure plays a role in firmly fixing the golf tee when it is inserted into the ground. In addition, it was possible to improve the compressive load compared to ABS golf tees while also decreasing the compressive stretching.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.91-97
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• 2018

This study carried out first a component survey on the domestic waste shipped into a waste disposal facility in B city, and then heavy metal analysis of each component according to the SRF standards. Based on this, this study explored the problems with domestic waste and measures to improve them. The results are as follows. The result of the survey of physical components show that paper accounted for the largest proportion with 20.5 %~59.9 %, metals (including batteries) among incombustibles accounted for 0.0~8.3 %, other inorganic substances, glass and ceramics accounted for 0.0~43.7 % and 0.0 %~19.6 % respectively. However, the proportion of coated viny and plastics, which have high lead and cadmium content, was rather high with 2.9 %~30.9 %. This suggests the possibility that actual concentration of lead and cadmium within SRF is likely to be higher. Among the 15 components contained in the waste brought into the waste disposal facility, 10 components (food waste, textiles, vinyl, plastics, wood, rubber and leather, paper, metals, electronic substrates, and nail polish) were analyzed according to assay samples (approximately 0.1 g and 0.3 g). The result of analysis shows that the amount of Cd and Pb detected in coated vinyl for 0.109 g of assay sample was 98.6 mg/kg and 20.6 mg/kg respectively; 117.0 mg/kg and 29.0 mg/kg respectively for 0.313 g of assay sample. This is high contents exceeding the Cd standard. As for wooden component, the amount of Pb was 480.0 mg/kg for 0.3 g of assay sample. This suggests that there always exists the possibility of exceeding the exposure level of heavy metals (Cd and Pb) in SRF as long as coated wood and vinyl plastics with high contents of Pb and Cd are shipped into the waste disposal facility; and the local government and the residents need to work hard to improve the situation including development of the machine to sort electronic substrates and batteries for separate collection of the waste of coated vinyl and plastics within domestic waste.

• Resources Recycling
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• v.26 no.2
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• pp.46-55
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• 2017

In this study, the design methodology of Radial Basis Function Neural Networks is developed with the aid of Laser Induced Breakdown Spectroscopy and also applied to the practical plastics sorting system. To identify black plastics such as ABS, PP, and PS, RBFNNs classifier as a kind of intelligent algorithms is designed. The dimensionality of the obtained input variables are reduced by using PCA and divided into several groups by using K-means clustering which is a kind of clustering techniques. The entire data is split into training data and test data according to the ratio of 4:1. The 5-fold cross validation method is used to evaluate the performance as well as reliability of the proposed classifier. In case of input variables and clusters equal to 5 respectively, the classification performance of the proposed classifier is obtained as 96.78%. Also, the proposed classifier showed superiority in the viewpoint of classification performance where compared to other classifiers.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.262-268
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• 2014

This research introduces the structural design and the validation results of the flexible high speed coupling for 2MW class wind turbine which transmit and cut off torque between gear box and generator. The high speed coupling requires electrical insulation to prevent electrical surface damages on gear box. Therefore glass fiber reinforced plastics is applied to absorb the vibration and deformation of power train and to transmit required torque. Finite element analysis was performed to optimize the thickness and accumulation number of glass fiber reinforced plastics. Torque limiter which cut off the abnormal torque is designed in frictional disc type. The design of the coupling was validated with the performance test of prototype.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.32-37
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• 2010

One of the most common engineering processes using plastics is the injection molding. In addition, plastics are utilized over the entire areas in our life including cars and home appliances among others for their characteristics with no deterioration even after a long time, as well as for their light weights in addition to their good durability. This paper aimed to minimize defects through prior analyses on the weld line, air traps, filling time, molding temperature and deformation patterns among others while carrying out interpretations on the cooling, filling and deformation in the injection process using the moldflow for rear lamp reflectors among components for a car in making parts through the coating process after injection.

• Advanced Composite Materials
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• v.16 no.4
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• pp.377-384
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• 2007

'Green' composites were fabricated from poly lactic acid (PLA) and bamboo fibers by using a conventional hot pressing method. The insulating properties of the PLA-bamboo fiber 'green' composites were evaluated by determination of the thermal conductivity, which was measured using a hot-wire method. The thermal conductivity values were compared with theoretical estimations. It was demonstrated that thermal conductivity of PLA-bamboo fiber 'green' composites is smaller than that of conventional composites, such as glass fiber reinforced plastics (GFRPs) and carbon fiber reinforced plastics (CFRPs). The thermal conductivity of PLA-bamboo fiber 'green' composites was significantly influenced by their density, and was in fair agreement with theoretical predictions based on Russell's model. The PLA-bamboo fiber composites have low thermal conductivity comparable with that of woods.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.7-11
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• 2000

In this paper was studied on the mechanical characteristics of Glass Fiber Reinforced Plastics(GFRP) of the steel bar it is to replace. The advantage of FRP such as high strength, low weight and chemical inertness or noncorrosiveness can be fully exploited. GFRP bar were successfully fabricated at l0mm nominal diameters of solid and hollow types using a pultrusion method. Tensile and bending specimens from this bar were tested and compared with behavior of GFRP rebar and steel bar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1104-1112
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• 2014

We present a design of the deployable lightweight antenna to be used in the satellite satisfying the required performance of the onboard sensor. The analysis is performed on the SAR antenna requirements, deploying techniques including material selection, and the characterization of deployable antenna with central disk. The performance of the solid deployable antennas and the mesh antennas are simulated, and the CFRP(Carbon Fiber Reinforced Plastics) samples are manufactured and tested. It is confirmed that the deployable antennas with central disk can meet the required performance by using deploying panels or mesh.

• Steel and Composite Structures
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• v.2 no.1
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• pp.1-20
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• 2002

Fiber-Reinforced Plastics (FRP) have received significant attention for use in civil infrastructure due to their unique properties, such as the high strength-to-weight ratio and stiffness-to-weight ratio, corrosion and fatigue resistance, and tailorability. It is well known that FRP wraps increase the load-carrying capacity and the ductility of reinforced concrete columns. A number of researchers have explored their use for seismic components. The application of concern in the present research is on the use of FRP for corrosion protection of reinforced concrete columns, which is very important in cold-weather and coastal regions. More specifically, this work is intended to give practicing engineers with a more practical procedure for estimating the strength of a deficient column rehabilitated using FRP wrapped columns than those currently available. To achieve this goal, a stress-strain model for FRP wrapped concrete is proposed, which is subsequently used in the development of the moment-curvature relations for FRP wrapped reinforced concrete column sections. A comparison of the proposed stress-strain model to the test results shows good agreement. It has also been found that based on the moment-curvature relations, the balanced moment is no longer a critical moment in the interaction diagram. Besides, the enhancement in the loading capacity in terms of the interaction diagram due to the confinement provided by FRP wraps is also confirmed in this work.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.316-325
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• 2021

Human-made plastics takes more than 500 years to break down and have been introduced into the ecosystem, threatening terrestrial and aquatic organisms. By 2025, there will be more than 250 million tons of plastics in the ocean. Although studies regarding microplastics have been exponentially increasing since 2015, international standards for defining the size classification for microplastics, as well as methods for qualitative/quantitative analysis have not been concluded yet. Thus, in this study, the latest trends in analytical methodologies have been reviewed. Further, the study suggests directions for future research approaches can be taken to analyze aquatic microplastics, which could be as useful information for establishing effective microplastic management policy via standardization in microplastic analysis.