• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1227-1233
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• 2011

Cellulose Electro-Active Paper (EAPap) has been known as a new smart material that is attractive for a bio-mimetic actuator due to its merits in terms of lightweight, dry condition, large displacement output, low actuation voltage and low power consumption. Cellulose EAPap is made by regenerating cellulose and aligning its micro-fibrils. This paper introduces several EAPap materials, which are based on natural cellulose and its hybrid nanocomposites mixed/blended with inorganic functional materials. By chemically bonding and mixing with carbon nanotubes and inorganic nanoparticles, the cellulose EAPap can be a hybrid nanocomposite that has versatile properties and can meet material requirements for many applications. Recent research trend of the cellulose EAPap is introduced in terms of material preparations as well as application devices including actuators, temperature and humidity sensors, biosensors, chemical sensors, and so on. This paper also explains wirelessly driving technology for the cellulose EAPap, which is attractive for bio-mimetic robotics, surveillance and micro-aerial vehicles.

• New & Renewable Energy
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• v.4 no.1
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• pp.37-43
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• 2008

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This paper describes the results for the mechanical and environmental tests of pretreatment system material. Mechanical Characteristics make differences between parent / weldment, Notch existence / non-existence and air/$H_2O$ conditions. As a result, the life of pipe lines needs to maintain and fit for the operating period. Based on actual situations, the tension test of pipe welding-parts is carried out varying the exposure time of hydrogen sulfide and the fatigue resistance test is also performed inserting a notch into the pipe welding part, being exposed to the hydrogen sulfide environment for 720 hours.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.509-512
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• 2006

We have many environmental problems by the polluted materials as a results of mechanical development these days. So people want to use building products made from natural things and take a good effect for people from those bio products. We can instance electron wave shelding, far infrared ray and anion emission, and anti-bacterial property as the latest trend of the bio building material. So we had a experiment to investigate how much bio materials affect concrete when we use in the concrete with cement substitution. We tested slump, 7days compressive strength, and air contents for physical properties of bio concrete. The result is that bio concretes with four bio ingredients have proper values comparing with target values for slump and air content but lower compressive strength than plain concrete.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.2
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• pp.75-80
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• 2015

The wet spinning of silk solution has attracted researchers' attention because of 1) unique properties of silk as a biomedical material and 2) easy control of the structure and properties of the regenerated silk fiber. Recently, studies have reported that different silkworm varieties produce silk with differences in the molecular weight (MW) and other mechanical properties of the regenerated silk fibroin (SF) film. In this study, we look at the effect of different Bombyx mori varieties on the wet spinning of SF. Although five regenerated SFs from different silkworm varieties have different MWs and solution viscosity, the wet spinnability and post drawing performance of regenerated SFs were not different. This result is due to low variability in the MW of the regenerated SF samples from the different silkworm varieties. In addition, unlike regenerated SF films, the mechanical properties of wet spun regenerated SF filament were not affected by silkworm variety. This result suggests that the mechanical properties of wet spun SF filament are less affected by MW than those of SF film are.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.55-62
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• 2005

This study was conducted to evaluate the application of a bio-composite made by the addition recycled fiber board flour as filler. Recycled fiber board (high density fiber board, HDF) flour was added to polyolefin polymer low density polyethylene (LDPE) and polypropylene (PP) for the preparation of bio-composite materials. The mechanical properties and processability of the recycled HDF flour filled LDPE and recycled HDF flour filled PP bio-composites were then measured and compared to those of wood flour (WF) and rice-husk flour (RHF) filled LDPE and PP bio-composites, respectively. The tensile and impact strengths of the recycled HDF flour filled LDPE and PP bio-composites had similar mechanical properties to those of the WF and RHF filled LDPE and PP bio-composites. To measure the processability, torques of the bio-composites were also measured. The torques of the HDF flour filled LDPE and PP bio-composites were lower than those of the WF and RHF filled polyolefin (PP and LDPE) bio-composites with a filler loading of 30 wt.%. This result showed definite processability, which was not related with the distribution of the particle size of the material added. The recycled fiber board flour filled bio-composites showed applicability as substitutes for the bio-composites currently used in the bio-composites industry.

• Textile Coloration and Finishing
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• v.30 no.1
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• pp.9-19
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• 2018

To prepare bio-inspired antifouling coating materials having similar structure with lotus, self-crosslinkable waterborne polyurethanes emulsions containing paraffin wax (CWPU/P0, 0.25, 0.5, 1.0, 1.5, 2.0, the number indicated the wt% of wax) were prepared by an emulsifier-free/solvent free prepolymer mixing process. The as-polymerized CWPU/P emulsions containing 0 - 1.00wt% of paraffin wax were found to be stable after 4 months, however, CWPU/P emulsions containing 1.50 and 2.00wt% of paraffin wax were unstable within 1 month storage. Considering the stability of emulsions, the optimum paraffin wax content was found to be about 1wt% to obtain stable antifouling coating emulsion material. The surface topology of CWPU/P film samples was characterized by atomic force microscopy (AFM). This study examined the effect of paraffin wax content on the surface roughness, water contact angle/surface energy, water swelling, light transmittance and tensile properties of CWPU/P film samples.

• Fire Science and Engineering
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• v.30 no.3
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• pp.16-22
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• 2016

Fire fighters rely on fire fighter protective clothing (FFPC) to provide adequate protection in the various hazardous environments. To enhance its protection performance, the FFPC material must be thick and thus it is difficult to achieve weight reduction. One of the methods of overcoming this problem, the addition of phase change material (PCM) to FFPC, is a new technology. In previous studies, the researches was mostly related to the temperature characteristics of the fibers incorporating PCM, but little information is available about its effect on burn injuries. Thus, in this study, the inhibitory effects of adding PCM to FFPC on second degree burns were investigated through numerical calculations. Thermal analyses of biological tissues and FFPC with embedded PCM exposed to several fire conditions causing severe tissue damage were studied by using a finite difference method based on the Pennes bio-heat equation. FFPC with embedded PCM was found to provide significantly greater protection than conventional fire fighting clothing, because the heat of absorption due to the phase change within the material is used to limit the heat conduction of the material.

• KSBB Journal
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• v.26 no.5
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• pp.422-426
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• 2011

Alginate bead has been supplemented with various polymers to control permeability and to enhance mechanical strength. In this report, fibroin-reinforced alginate hydrogel was prepared, in which spatial localization of fibroin molecules was investigated. Confocal laser scanning microscopy revealed that fibroin molecules formed a fibrous network in the alginate-fibroin beads, which was expected to enhance mechanical strength as same as in many composite materials. Uniaxial compression test showed that fibroin-reinforced alginate beads had increased mechanical strength only after methanol treatment that caused ${\beta}$-sheet formation among fibroin molecules. Simultaneous curing and dialysis of alginate beads were carried out to remove excesscalcium but to retain fibroin in the dialysis chamber, which fabricated beads without internal fibrous fluorescent stains. Fibroin molecules were only found beneath the surface of the beads. The fibroin-diffused shell was further processed to form a thick wall after drying or was mobilizedto the centre of the bead by methanol treatment. Accordingly, the structure analyses provide processing methods of fibroin to form a wall or center clumps, which could be applied to design controlled delivery device.

• Composites Research
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• v.36 no.5
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• pp.297-302
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• 2023

There are several methods for shaping foams, but the most commonly used methods involve the use of resin mixed with a foaming agent, which is then foamed under high temperature and pressure in the case of compression foaming, or foamed under high temperature without applying pressure in the case of atmospheric foaming. The polymers used for foaming require design and analysis of optimal foaming conditions in order to achieve foaming under ambient pressure. Environmentally friendly bio-based polymers face challenges when it comes to foaming on their own, which has led to ongoing research in blending them with resins capable of traditional foam production. This study investigates changes in the characteristics of bio-based polymer-EVA blend foams based on variations in the content of bio-based polymers and explores the optimal foaming conditions according to crosslinking. The correlation between foaming characteristics and mechanical properties of the foams was examined. Through this research, we gained insights into how the content of bio-based polymers affects the properties of foams containing bio-based polymers and identified differences between ambient pressure and high-pressure foaming processes. Additionally, the feasibility of commercializing bio-based polymer-EVA composite foams was confirmed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.70-77
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• 2015

This paper develops and evaluates a mechanical machining process which involves drilling on PVS material. According to the material, two treatment experiments were conducted, one involving drilling in a wet condition or using a lubricant and one involving drilling in a dry condition with no lubricant. Drilling in a dry condition showed better performance in terms of the cutting time than in the wet condition. Otherwise, the wet condition has several advantages. The lubricant influenced the burr diameter size and minimized the temperature on the surface of the work piece. During the wet condition drilling process, a smaller burr diameter size was noted as compared to the dry condition. The temperature showed a linear correlation with the drill bit size, where a least-square analysis provided an $R^2$valuewhichexceeded 0.95. The wet condition required more cutting time than the dry condition. In this condition, the water provides a lubrication effect. A thin layer between the cutting edges and the surface of the work piece is formed. The chip formation is affected by the drilling depth. The color on the tips of the chips was darker than in the initial condition. No correlation between the drilling depth and the bore roughness was noted, but the variation of the cutting speed or the RPM influenced the roughness of the bore. The optimum cutting speed ranged from 40 RPM to 45 RPM in the condition which provided the finest roughness surface.