• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.990-997
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• 2005

Many products, such as gasoline, polymer plastics, alloys, and ceramics are manufactured by mixing two or more ingredients or components. When we are to develop new mixture products, we must deal with a long list of potentially important component variables. This paper introduces some design methods for many mixture variables and some analysis tools for screening important variables out of the many candidate variables. The results of this paper will be helpful to engineers who work in the research and development sector of chemical, polymer, alloys, and electro-material industries.

• Journal of Forest and Environmental Science
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• v.31 no.4
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• pp.297-302
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• 2015

With the intention to solve environmental problems caused by synthetic plastics from petroleum resources, biodegradable polyurethane foams and thermosetting moldings were prepared from biomass, such as wood and wheat bran by liquefaction method. Biodegradability of these biomass-based polymeric materials was investigated. In activated sludge, polyurethane foams from liquefied wheat bran and thermosetting molding from phenolated wood were decomposed approximately 14% and 29% for 20 days, respectively. One of the wood fungi, Coriolus versicolor was able to grow without supplemental nutrition, only with distilled water and polyurethane foam as a nutrition source. Risk assessments were also conducted and results showed that estrogenicity, mutagenicity, and carcinogenicity were not observed in the extractives of biomass- based polymeric materials.

• IE interfaces
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• v.19 no.2
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• pp.117-123
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• 2006

Many products, such as gasoline, polymer plastics, alloys, and ceramics are manufactured by mixing two or more ingredients or components. When we are to develop new mixture products, we must deal with a long list of potentially important component variables. This paper introduces some mixture screening designs, analysis tools for screening important variables, and a guideline for applying these analysis tools. The results of this paper will be helpful to engineers who work in the research and development sector of mixture product industries.

• Journal of Mechanical Science and Technology
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• v.14 no.5
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• pp.477-482
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• 2000

This study discusses a non-contact optical technique (electronic speckle pattern interferometry) that is well suited for thermal deformation measurement without any surface preparation and compensating process. Fiber reinforced plastics ($[0]_{16},\;[0/90]_{8S}$) were analyzed by ESPI to determine their thermal expansion coefficients. The thermal expansion coefficient of the transverse direction of a uniaxial composite is evaluated as $48.78{\times}10^{-6}(1/^{\circ}C)$. Also, the thermal expansion coefficient of the cross-ply laminate $[0/90]_{8S}$ is numerically estimated as $3.23{\times}10^{-6}(1/^{\circ}C)$ that is compared with that measured by ESPI.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.175-176
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• 2003

Generally, The protone exchange membrane (PEM) contains cationic exchange groups such as SO3$\^$-/ group. The poly(styrene sulfonic acid) (PSSA) and its copolymers are widely studied because of easily synthetic method and higher conductivities. However, PSSA is not used individually because of poor physical properties such as brittleness and relatively lower Tg. So some researchers are concerned engineering plastics (EP) such as polyimides, polysulfone, polyketones, and poly(2,6-dimethyl-1,4-phenylene oxide) (MPPO) etc. (omitted)

• Advanced Composite Materials
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• v.18 no.3
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• pp.287-295
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• 2009

$\beta$-Tricalcium phosphate ($\beta$-TCP) particles reinforced bioresorbable plastics poly-L-lactide (PLLA) composites were prepared by injection molding. The nominal weight ratio of $\beta$-TCP was selected as 5, 10 and 15%. In order to clarify effects of the PLLA crystallinity on the mechanical properties, the specimens were heat treated isothermally. Results of differential scanning calorimetry indicated that the PLLA crystallinity increased with increasing heat treatment temperature. Bending and compressive tests were conducted on the specimen with different $\beta$-TCP contents and crystallinities. The results show that the bending and compressive moduli increased with increasing $\beta$-TCP contents and crystallinity. On the other hand, bending strength decreased with increasing $\beta$-TCP contents. Maximum bending strength was obtained at the heat treatment of $70^{\circ}C$ for 24 h, whereas compressive 0.2% proof strength increased with increasing heat treatment temperature. This difference is attributed to the difference in the microscopic damages.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.12-18
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• 2022

In recent years, the impact of microplastics (MPs) on ecosystems is a serious problem. Since MPs are difficult to recover once they are dispersed into the environment, it is important to remove them at the source. We proposed a magnetic separation of primary MPs (plastics manufactured in minute sizes) sized 10-100 ㎛ that has not been removed in the sewage process, based on the magnetic seeding process. In this study, we used magnetite as a magnetic seeding agent, and conducted magnetic separation experiments in the continuous process using a superconducting solenoidal magnet to investigate the feasibility of practical magnetic separation system of MPs. As a result, 85% separation rate was obtained by continuous separation using high gradient magnetic separation (HGMS) with hydrophobically treated magnetite as a magnetic seeding agent.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1872-1879
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• 2016

The techniques to recycle and reuse plastics attract public attention. These public attraction and needs result in improving the recycling technique. However, the identification technique for black plastic wastes still have big problem that the spectrum extracted from near infrared radiation spectroscopy is not clear and is contaminated by noise. To overcome this problem, we apply Raman spectroscopy to extract a clear spectrum of plastic material. In addition, to improve the classification ability of fuzzy Radial Basis Function Neural Networks, we apply supervised learning based clustering method instead of unsupervised clustering method. The conditional fuzzy C-Means clustering method, which is a kind of supervised learning based clustering algorithms, is used to determine the location of radial basis functions. The conditional fuzzy C-Means clustering analyzes the data distribution over input space under the supervision of auxiliary information. The auxiliary information is defined by using k Nearest Neighbor approach.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.960-963
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• 2002

In recent days the more use of CFRP composite is in the airplane, automobile, and sport goods, etc., the more necessity of research on it in this engineering. In this research, the CFRP composite specimen are fabricated by 48 CFRP plies with 8 orientation angles, and the specimens are drilled with 3 tools. The results are analyzed with consideration of cutting force, type of tools and fabrication condition. The specimens with each drilling conditions are also investigated with SEM. The optimal drilling conditions such as drill types and cutting force with respect to the fabricating condition are studied.

• Structural Engineering and Mechanics
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• v.18 no.1
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• pp.21-40
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• 2004

In this paper, we modify the L-L model (Li et al. 2003) and extend the application of this model to concrete confined by both steel reinforcement and CFRP. Thirty-six concrete cylinders with a dimension of ${\varphi}30{\times}60$ cm were tested to verify the effectiveness of the proposed model. The experimental test results show that different types of steel reinforcement have a great effect on the compressive strength of concrete cylinders confined by steel reinforcement, but the different types of steel reinforcement have very little effect on concrete cylinders confined by both steel reinforcement and CFRP. Compared with the stress-strain curves of confined concrete cylinders, we can conclude that the proposed model can provide more effective prediction than others models.