• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.34-41
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• 2000

Recently many scientists have tried to synthesize biodegradable polymers due to durable and non-biodegradable products of conventional synthetic plastics when these were wasted in nature. So to reuse the wastepapers for biodegradable polymer resources, ONP (old newsprint), OCC (old corrugated containerbpard) were carried out by the pretreatment of chlorinite, hypochlorite and oxygen-alkali treatment conditions. For manufacturing of biodegradable polymer with wastepaper, this study performed to investigate change of chemical components and optimal pretreatment condition. The summarized results in this study were as follows: Lignin content in ONP and OCC was was higher than in MOW and ash content was the highest in MOW. More amount of ash components were reduced by wet defiberation than by dry defiberation. Wet defiberation fiber are better than dry defiberated fiber in chemical pretreatment condition for wastepapers, and the best result was obtained in the condition of sodium chlorite at $70^{\circ}C$, because it has high delignification ratio, ${\alpha}$-cellulose contents and degree of polymerization in this treatment condition. Oxygen-alkali treatment condition is the worst method because of low yield, low degree of polymerization in this pretreatments.

• Journal of Bio-Environment Control
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• v.24 no.4
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• pp.326-332
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• 2015

The effect of biodegradable mulching film on the growth and development of garlic were investigated in order to develop eco-friendly weed control techniques. The treatments included biodegradable film (Bio-De) and black (Black-PE), green (Green-PE), transparent (Trans-PE) polyethylene mulching films. Non-mulched, bare soil (Non-mulching) was used as a control. Light transmittance value among tested mulching films was the highest in Trans-PE (86.1%) followed by Bio-DE and Green-PE, and the lowest value was observed for the Black-PE (1.1%). All mulching films without exclusion elevated soil temperature, especially Trans-PE and Bio-DE compared to bare soil. Plant height and mean bulb weight were increased due to mulching films with the highest values observed for Trans-PE and Bio-DE treatments. After seven months of field application there were no significant degradation signs on PE plastic films, whereas it was easy to see horizontal cracks on the Bio-DE film surface after five month of usage.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.167-177
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• 2013

The use of mechanical anastomosis coupler instead of sutures has been increasing in microvascular anastomosis surgery. However, non-biodegradable anastomosis coupler has problems such as not only inflammatory reaction but also remaining permanently in operation wound. Therefore, we fabricated biodegradable anastomosis coupler using injection molding process to overcome the limitation of non-biodegradable anastomosis coupler. In various injection molding process conditions, the shrinkage was calculated with different cylinder temperatures and injection molding pressures and anastomotic strength was measured. As a result, changes in shrinkage hole part larger than the pin part. In addition, the shrinkage in the cylinder at higher temperatures increase. However, the higher the injection pressure, shrinkage tends to decrease, respectively. In-vitro degradation behavior of PCL anastomotic coupler evaluated for 12 weeks, water uptake was increased and molecular weight was accompanied by a reduction in mass of the biological degradation and reduction of anastomotic strength was confirmed. However, decreased levels of anastomotic strength enough to exceed the requirements of preclinical surgery, PCL microvascular anastomosis coupler suitable candidate materials that could identify.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.35-45
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• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.41-49
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• 2005

Styrofoam as shock-absorbing materials for packaging has been regarded as one of non-biodegradable products leading to soil contamination at a landfill and release of dioxine during its incineration. For avoiding severe burdens on our environments by styrofoam, it must be replaced by environment-friendly materials. In order to evaluate availability of pulp fibers as a substitute for styrofoam, various extrusion processes were applied for making optimal biodegradable products. Then thermomechanical pulp fibers made of Pinus radiata and Pinus rigida were uniformly mixed with other additives such as starch and polyvinyl alcohol prior to expansion. The physical properties of the final products were examined by measuring expansion efficiency, compression strength, and elastic modulus. Wheat starch played a key role to maintain optimal flowing conditions within the barrel of the extruder irrespective of addition of soluble starch and polyvinyl alcohol. However, as the amounts of wheat starch in raw-materials increased, the elastic modulus of the expanded materials greatly increased. High elastic modulus is not suitable as shock-absorbing products for packaging. Thus the wheat starch must be added at a minimum if possible, that is, below 20% based on oven-dried weight of pulp fibers. the elastic modulus of the expanded products was decreased as their moisture contents increased. For the products containing 20% wheat starch, the lowest elastic modulus, 844.64 kPa was obtained under 10% of the moisture content. This was similar to that of styrofoam.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.537-542
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• 2008

Textile industry has been recognized as an important pollution source due to its consumption of large volumes of water and chemicals. Textile wastewater contains very diverse chemicals in types and composition, among them the presence of dyes is highly visible and undesirable. In spite of these problems, there has not been a proper control for the wastewater because many dyes are difficult to be degraded or decolorized due to their complex structure and synthetic characteristics. This study has been progressed to evaluate more easily the potential decolorization of advanced treatment processes. It has been surveyed with the Y textile complex wastewater treatment plant, the raw wastewater has appeared very difficult biodegradability by 4.7 of $CODcr/BOD_5$ and 1,158.9 degree of color. In view of CODcr fractions, biodegradable COD portion was 46.4%, colloidal COD and real soluble COD was 45.3% and 31.5% each others. From research on unit processes, the degradable coefficient (k) became from 0.065 to $0.125d^{-1}$ by the processes, the decolorization appeared best efficiency by 30.1% (458.4 degree) in pre-ozone process. On the effluent from the biological process, the filterable CODcr became 129.3 mg/L, the biodegradable portion appeared 64.7% (83.6 mg/L), and the fixed dissolved solid (FDS), non-reactivity (NR), appeared very heavy portion by 80.5% (1,659.0 mg/L).

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.112-117
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• 2016

This research compared the tensile performance of the vegetation mat, which was developed byu using the rapidly growing biodegradable plastic, Poly Lactic Acid(PLA), according to the biodegradation period. The test applied the method defined by Korean Standard KS. In the result of experiment using single-material PLA mesh and PLA plastic, the tensile strength and molecular weight were inverse-proportional to the 5 months of biodegradation period. The thickness of PLA mesh was increased by 11.2~13.4% while the tensile strenth of it was reduced by 32.4~55.4%. The tensile strength and molecular weight of PLA plastic were also reduced over time. However, the tension test of vegetation mat comprised of PLA mesh, non-woven fabric (including seeds), and jute net didn't have specific tendency.

• Polymer(Korea)
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• v.35 no.3
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• pp.260-264
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• 2011

Biodegradable polymeric stents have been issued to replace the existing non-degradable metal stents due to relatively improved biocompatibility and low side effects. Fundamentally, all the stents must possess the desired mechanism strength, especially, compression or radial force to maintain the diameters of expanded vessels. Therefore, this study suggests a helical structure and focused on the relation between the lateral compression and structural factors, Unlike a cylindrical model, the radial force of the helical model is proportional to the thickness and the length to the power of one, whereas the diameter to the power of 1.6. The function obtained from these results might provide the fundamental information to design and prepare the stem for clinical applications.

• Composites Research
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• v.22 no.4
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• pp.41-49
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• 2009

Natural fiber reinforced composites are emerging as low-cost, lightweight, recyclable, and eco-friendly materials. These are biodegradable and non-abrasive. Due to eco-friendly and biodegradable characteristics of natural fibers, they are being considered as potential candidates to replace the conventional fibers. The chemical, mechanical, and physical properties of natural fibers have distinct features depending upon the cellulose content of the fibers which varies from fiber to fiber. The mechanical properties of composites are influenced mainly by the adhesion between matrix and fibers. Several chemical and physical modification methods of fiber surface were incorporated to improve the tiber-matrix adhesion resulting in the enhancement of mechanical properties of the composites. This paper outlines the works reported on natural tiber reinforced composites with special reference to the type of fibers, polymer matrix, processing techniques, treatment of fibers, and fiber-matrix interface.

• Proceedings of the Korean Fiber Society Conference
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• 1999.04a
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• pp.83-85
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• 1999