• Composites Research
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• v.26 no.5
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• pp.303-308
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• 2013

Carbon fiber (CF) reinforced polypropylene (PP) compositeis was increased to amount consumed. In this study, recycle of composites by recycle times. CF was containing 20%. Mechanical and interfacial propertis of CF/PP was evaluation for number of recycle time. Mechanical assessment of CF/PP was tension, bending, fatigue tension test and izod test method. Interfacial assessment of CF/PP was wettability test and FE-SEM of fracture surface method. Fiber and matrix was changed to recycle time. The more recycle of CF/PP, the more interfacial bonding was decreased. Because fiber and matrix was damaged to thermal damage. And then reinforced CF was shorter than original shape.

• Polymer(Korea)
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• v.24 no.6
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• pp.845-853
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• 2000

The optimum cure cycle and carbonization condition were selected by the DSC and TGA analysis and green bodies were prepared by the method of hot press molding and then carbonized up to 140$0^{\circ}C$. Additives such as graphite powder, carbon black, milled carbon fiber and carbon fiber mat, which were considered to be effective in improving the interlaminar shear strength, were also added to check their effects on the density and porosity of products. Then, their relations with mechanical properties such as ILSS and flexural strength were investigated. The composites added 9 vol% of graphite powder showed the greatest values of ILSS and flexural strength. Otherwise, in case of adding carbon black, the composites showed the slight improvement of ILSS at its contents of 3 vol% but the flexural strength was decreased. When milled carbon fiber and carbon fiber mat were added, the lack of resin and the heat shrinkage during the carbonization caused the delamination, resulting in decreasing the density, ILSS and flexural strength.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.10a
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• pp.17-18
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• 2008

접착물질인 PP(Polypropylene)가 함유되지 않은 섬유 폐기물을 Niagara beater을 이용한 습식 분쇄하여 판상형태의 Sheet에 접착물질인 KSL 103과 KSL 203을 물과 1:1로 혼합사용 분무한 제품의 경우가 굴곡휨강도, 인열강도가 우수하였고, PP의 사용의 배제로 Press시의 온도를 $180^{\circ}C$에서 $130^{\circ}C$로 낮추어 작업이 가능하고 Texon에서 부여하기 힘든 굴곡휨강도와 굴곡강도가 우수한 결과를 나타내었다.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.4
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• pp.62-71
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• 2013

This study was carried out to develope a pre-treatment technology for anaerobic digestion. Breaking down large particles into smaller particles enhances the performance of anaerobic digestion by increasing the hydrolysis of particles. A degree of hydrolysis is the most important factor determining the overall efficiency of methane production. Three types of pre-treatment devices (blade-type crusher, ozonization system, cavitation system) were set up and operated to crush solids in pig slurry in order to enhance biodegradability. The effect of pre-treatment on decreasing granular size within pig slurry by three experimental devices were compared. The highest performance of granulization of pig slurry was attained in a combination of blade-type crusher and ozonization system. In batch experiment, there was an improvement of the methane potential by combined pretreatment with crusher and cavitation. In case of pre-treated slurry, biogas and methane production were 325.9 L and 59.7% respectively, while, in untreated slurry, the production were lower; 298.8 L and 55.7%, respectively. These results indicate that higher anaerobic digestion efficiency of pig slurry can be obtained through the pre-treatment.

• Korean Journal of Materials Research
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• v.23 no.2
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• pp.89-97
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• 2013

The study of grinding behavior characteristics on aluminum powders and carbon nano tubes (CNTs) has recently gained scientific interest due to their useful effect in enhancing advanced nano materials and components, which significantly improves the property of new mechatronics integrated materials and components. We performed a series of dry grinding experiments using a planetary ball mill to systematically investigate the grinding behavior during Al/CNTs nano composite fabrication. This study focused on a comparative study of the various experimental conditions at several variations of rotation speeds, grinding time and with and without CNTs. The results were monitored for the particle size distribution, median diameter, crystal structure from XRD pattern and particle morphology at a given grinding time. It was observed that pure aluminum powders agglomerated with low rotation speed and completely enhanced powder agglomeration. However, Al/CNTs composites were achieved at maximum experiment conditions (350 rpm, 60 min.) of this study by a mechanical alloy process for Al/CNTs mixed powders because the grinding behavior of Al/CNTs composite powder was affected by addition of CNTs. Indeed, the powder morphology and crystal size of the composite powders changed more by an increase of grinding time and rotation speed.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.191-203
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• 2018

This study was investigated the effect of the morphology change of copper (Cu) powders under the different rotational speed and milling time by using three kinds of grinding media with different size and materials, and performed DEM simulations of ball behavior. In order to clarify the mechanism of grinding by three - dimensional simulations of the ball behavior in a traditional ball mill, the force, kinetic energy, and medium velocity of the grinding media were calculated. In the simulation, the amount of change of the input energy was also calculated by adjusting the rotational speed, ball material, kinetic velocity, and friction coefficient in the same as the actual experimental conditions. The scanning electron microscope results show that the particle morphology changes from irregular to spherical when the ball size is small.

• Clinics in Shoulder and Elbow
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• v.10 no.1
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• pp.84-91
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• 2007

Purpose: The aim of this study was to report seven cases of metallic radial head prosthesis and present the limit of use in Korea. Materials and Methods: Metallic radial head arthroplasty was performed on 7 patients between April 2006 and December 2006, who had complex elbow injury including comminuted radial head fracture. Indication, operative findings and outcome were assessed. Availability and payment of implant were investigated. Results: All of the patients had more than one associated injury including coronoid fracture, olecranoan fracture, and ligament ruptures. According to Mason classification, there were three type III and four type IV fractures. All radial head fractures were too comminuted to reconstruct. There were two excellent results, four good, and one poor, as graded by Mayo score. There were no patient with instability and implant related complications. Insufficient supply of implant did not enable to do scheduled surgery in 2 cases. Current medical insurance did not cover charge for radial prosthesis, five patients could not help paying for that by themselves. Conclusion: Metallic radial head implants are useful when the radial head cannot be repaired reliably. Preoperative preparing and coverage by medical insurance based on appropriate indication are helpful for decision for a treatment option.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.27-33
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• 2016

Phenolic resin has excellent heat resistance and good mechanical properties as a thermosetting resin. However, its thermosetting characteristics cause it to produce a non-recyclable waste in the form of sprue and runner which is discarded and represents up to 15~20% of the overall products. Forty thousand tons of phenolic resin sprue and runner are disposed of (annually). The (annual) cost of such domestic waste disposal is calculated to be 20 billion won. In this study, discarded phenol resin scraps were pulverized and treated by silanes to improve their interfacial adhesion with HDPE. The sizes of the pulverized pulverulent bodies and fine particles were (100um~1000um) and (1~100um), respectively. The pulverized phenol resin was treated with 3-(methacryloyloxy) propyltrimethoxysilane and vinyltrimethoxy silane and the changes in its characteristics were evaluated. The thermal properties were evaluated by DSC and HDT. The mechanical properties were assessed by a notched Izod impact strength tester. When the silane treated phenol resin was added, the heat distortion temperature of HDPE increased from $77^{\circ}C$ to $96^{\circ}C$ and its crystallinity and crystallization temperature also increased. Finally, its impact strength and tensile strength increased by 20% and 50%, respectively, in comparison with the non-treated phenol resin.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.1
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• pp.63-68
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• 2010

CNT and permalloy composite plating was investigated. CNTs were pretreated prior to electroplating to disassemble the tangled CNT lumps. The ball milling as a physical pretreatment and the acid treatment as a chemical pretreatment were used. 10M nitric acid and 10 M sulfuric acid were used for the chemical pretreatment. Sulfuric acid was more effective than nitric acid to disassemble CNT lumps. To disperse CNT in the solution, surfactants were used. SDS, Triton X-100 and PAA were used for this purpose. More CNTs were incorporated in permalloy coating when PAA was used as a surfactant. The surface morphologies were observed with FESEM after electroplating CNT and permalloy. The current densities were varied from 10 to $80\;mA/cm^2$ and the concentration of PAA was fixed at 2 g/L. The optimum current density without surface cracks was $20\;mA/cm^2$. The crystallinity of the deposit was analyzed with XRD and the surface hardness was analyzed with Vicker's hardness tester. The corrosion behavior was analyzed with polarization plot. The physical properties of permalloy were not improved with CNT composite plating.

• Journal of the Mineralogical Society of Korea
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• v.15 no.4
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• pp.283-291
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• 2002

Dry-based processes such as crushing, milling, sieving, magnetic and gravity separation were employed in order to investigate the purification characteristics of bentonite. The CECs of Gampo 13 and 35 bentonites were estimated at 88.3 and 93.3 meq/100 g and the samples contained quartz and feldspar as impurity minerals. According to the physical properties of constituent minerals of bentonite, the purification techniques were adopted to enhance the grade of montmorillonite High grade of montmorillonite could be obtained by the combination of each process. Consequently, the recovery of final products of Gampo 13 and 35 bentonite were 68.6 and 49.5%, and the CECs of them were 96.9 and 109.6 meq/100 g, respectively.