• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.1-10
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• 2003

Shredded waste newspapers, waste acrylic raw fibers, and urea-formaldehyde (UF) adhesives, at 10% by weight on raw material, were used to produce recycled waste paper-waste acrylic raw fiber composite boards in laboratory scale experiments. The physical and mechanical properties of fire retardant treated recycled waste paper-waste acrylic raw fiber composite boards were examined to investigate the possibility of using the composites as internal finishing materials with specific gravities of 0.8 and 1.0, containing 5, 10, 20, and 30(wt.%) of waste acrylic raw fiber and 10, 15, 20, and 25(wt.%) of fire retardant (inorganic chemical, FR-7^®) using the fabricating method used by commercial fiberboard manufacturers. The bending modulus of rupture increased as board density increased, decreased as waste acrylic raw fiber content increased, and also decreased as the fire retardant content increased. Mechanical properties were a little inferior to medium density fiberboard (MDF) or hardboard (HB), but significantly superior to gypsum board (GB) and insulation board (IB). The incombustibility of the fire retardant treated composite board increased on increasing the fire retardant content. The study shows that there is a possibility that composites made of recycled waste paper and waste acrylic raw fiber can be use as fire retardant internal finishing materials.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.99-103
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• 2006

Use of recycled fibers in papermaking has been increased for economical and environmental reasons. Recycled panels are major liber resources for brown grades and newsprints. Since the recycled fibers have disadvantageous properties as raw materials for papermaking it is of great importance to optimize the use of these recycled fibers. OCC (Old Corrugated Containers) is the major fiber source for linerboards and corrugating mediums that require diverse specification in strength properties. Many studies have been focused to overcome the problems of strength reduction of brown grades when recycled fibers are used as raw materials. The problem of strength loss for papers made from recycled fibers is closely associated with the increased amount of fines in recycled fibers and hornification of fibers. Fines contained in the recycled fiber resources cause problems not only in paper properties but also in process runnability. This shows that the optimal management and proper use of fines in recycling papermaking system are critical to get most benefits of using recycled fibers. In this study some approaches for optimal use of fiber fines in recycled paper mill have been investigated. Stock samples, prepared in the laboratory and obtained from a recycling plant were used. Fractionation of these samples was made using Sweco screen. And the effect of the addition of polyelectrolytes including cationic PAM and PEI on drainage and retention was evaluated. Different methods of polymer addition were compared to find the most effective ways of treating recycled fiber stocks with polyelectrolytes. Addition of polyelectrolytes to the short fiber fraction was most effective in retention and drainage. The influence of the charge and molecular weight of these two polymers has been examined and discussed.

• Geomechanics and Engineering
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• 제19권1호
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• pp.37-47
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• 2019

The main objective of this study is to evaluate and compare the efficiency of ordinary Portland cement (OPC) in enhancing the unconfined compressive strength of soft soil alone and soft soil mixed with recycled tiles. The recycled tiles have been used to treat soft soil in a previous research by Al-Bared et al. (2019) and the results showed significant improvement, but the improved strength value was for samples treated with low cement content (2%). Hence, OPC is added alone in this research in various proportions and together with the optimum value of recycled tiles in order to investigate the improvement in the strength. The results of the compaction tests of the soft soil treated with recycled tiles and 2, 4, and 6% OPC revealed an increment in the maximum dry density and a decrement in the optimum moisture content. The optimum value of OPC was found to be 6%, at which the strength was the highest for both samples treated with OPC alone and samples treated with OPC and 20% recycled tiles. Under similar curing time, the strength of samples treated with recycled tiles and OPC was higher than the treated soil with the same percentage of OPC alone. The stress-strain curves showed ductile plastic behaviour for the untreated soft clay and brittle behaviour for almost all treated samples with OPC alone and OPC with recycled tiles. The microstructural tests indicated the formation of new cementitious products that were responsible for the improvement of the strength, such as calcium aluminium silicate hydrate. This research promotes recycled tiles as a green stabiliser for soil stabilisation capable of reducing the amount of OPC required for ground improvement. The replacement of OPC with recycled tiles resulted in higher strength compared to the control mix and this achievement may results in reducing both OPC in soil stabilisation and the disposal of recycled tiles into landfills.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.126-126
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• 2003

• 한국환경보건학회지
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• 제28권2호
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• pp.41-49
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• 2002

Resource recovery and recycling of materials and products including polyurethanes are viewed as a necessity in today's society. The problems of recycling polyurethane wastes has major technological, economic and ecological significance because polyurethane itself is relatively expensive and its disposal by burning is also costly. In general, the recycling methods for polyurethane could be classified as mechanical, chemical and physical. In the chemical recycling method, there ate hydrolysis, glycolysis, pyrolysis and aminolysis. This study was carried out glycolysis using new method such as sonication and catalyzed reaction. There are kinds of recycled polyols were produced by current method(glycolysis) but, this study were with catalyzed reaction and sonication as decomposers and the chemical properties were analyzed. The reaction results in the formation of polyester urethane diols and then the OH value which is determined by the quantity of diol used for the glycolysis conditions. The glycolysis rates by sonication and catalyzed reaction for the various glycols, increased as: PPG

• 한국건축시공학회지
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• 제12권5호
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• pp.490-502
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• 2012

The use of recycled aggregate, even for low-performance concrete, has been very limited because recycled aggregate, which contains a large amount of old mortar, is very low in quality. To produce a high-quality recycled aggregate, removing the paste that adheres to the recycled aggregate is very important. We have conducted research on a complex abrasion method, which removes the component of cement paste from recycled fine aggregate by using both a low-speed wet abrasion crusher as a mechanical process and neutralization as chemical processes, and well as research on the optimal manufacturing condition of recycled fine aggregates. Subsequently, we evaluated the quality of recycled fine aggregate manufactured using these methods, and tested the specimen made by this aggregate. As a result, it was found that recycled fine aggregates produced by considering the aforementioned optimal abrasion condition with the use of sulfuric acid as reactant showed excellent quality, recording a dry density of 2.4 and an absorption ratio of 2.94. Furthermore, it was discovered that gypsum, which is a reaction product occurring in the process, did not significantly affect the quality of aggregates. Furthermore, the test of mortar using this aggregate, when gypsum was included as a reaction product, showed no obvious retarding effect. However, the test sample containing gypsum recorded a long-term strength of 25.7MPa, whereas the test sample that did not contain gypsum posted a long-term strength of 29.4MPa. Thus, it is thought to be necessary to conduct additional research into the soundness and durability because it showed a clear reduction of strength.

• 펄프종이기술
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• 제46권6호
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• pp.94-102
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• 2014

The physical and chemical properties of recycled fibers from mixed waste paper are more and more deteriorated because of unknown history of recycling times. In order to improve the mechanical properties of liner paper, the recycled fibers from wasted cotton clothes were used in papermaking process, and their applicabilities were evaluated in several points of fiber modification. Thus, two kinds of fiberizing methods from waste cotton clothes were considered by using rotary sandpaper and grinder mill. Finally, the rotary sandpaper method was relatively desirable in preserving longer fiber length and fibrillated fiber surface. The recycled cotton fibers by swelling treatment with NaOH and bleaching with reductive chemicals were mixed with OCC fibers, and the handsheets were prepared to basis weight of $80g/m^2$ and evaluated the mechanical properties of paper. The fibrous properties showed outstanding results in freeness and WRV improvements by alkali treatment and high brightness by reductive bleaching treatment. The physical and mechanical properties of sheet by mixing OCC fibers and recycled cotton fibers were also highly improved in tensile, burst strength and specially folding resistance.

• 한국건설순환자원학회논문집
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• 제6권2호
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• pp.112-118
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• 2011

환경에 관련된 인식이 급격하게 변화되는 현재의 흐름에 따라 도로포장부문에서 별다른 주목을 받지 못하던 재생아스팔트포장에 관한 실제 성능 및 적용성을 알아보고자 실내실험, 현장 시공 및 공용성능에 대한 추적조사를 실시하였습니다. 문헌고찰을 통하여 재생아스팔트포장의 현장적용에 대한 정보를 수집하였고 실제 생산현장과 접촉하여 시료를 획득하여 배합설계와 현장시공을 2차례에 걸쳐 실시하였습니다. 배합설계(실내실험)에서는 재생골재의 세립분 및 골재파쇄로 인해 배합설계에 시간소모가 많았으며 목표입도를 맞추는데 어려움이 있었으나, 공용성능 추적조사에서는 시험시공구간의 균열이 시공후 5-6년 이후에도 발견되지 않았고 기타 포장파손도 발견되지 않아 양호한 상태를 나타내고 있었습니다. 또한, DSR을 이용한 재생바인더에 대한 피로시험결과, 일반적으로 선택되고 있는 재생골재 투입비율 30%에서 바인더의 피로수명이 베이스 아스팔트에 비하여 약 30~40%정도 감소하는 것으로 나타났습니다. 결론적으로 재생아스팔트포장의 취약점으로 알려진 균열문제는 충분한 품질관리를 통하여 극복될 수 있으며 이 품질관리에는 적절한 바인더 선택이 매우 중요할 것으로 판단됩니다. 재생아스팔트포장은 일반아스팔트포장과 비교하여 품질에 큰 차이는 없으며 재생골재의 투입비율과 바인더 선택을 적절히 하는 경우에는 국가적으로 이산화탄소 발생 억제를 통한 환경보호와 비용절감을 동시에 이룰 수 있을 것으로 보입니다.

• 콘크리트학회논문집
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• 제17권4호
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• pp.499-504
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• 2005

폴리머콘크리트는 시멘트 콘크리트에 비해 강도와 내구성에 탁월한 성능을 가지고 있지 때문에 건설현장에서도 다양한 용도로 개발되어 널리 사용되고 있다. 그러나 폴리머콘크리트는 그 결합재로 쓰이는 수지의 가격이 높아 경제적인 면에서는 다소 불리하여 기존의 수지를 대체할 수 있는 결합재에 관한 연구가 진행되고 있다. PET를 재활용한 폴리머콘크리트는 산업폐기물을 재활용하여 경제적인 건설 신소재를 개발할 수 있어 그 영역이 점차 확대될 것으로 전망된다. 본 연구에서는 하수관거 및 폐수 시설 등에서 발생하고 있는 황산에 의한 피해를 줄이기 위한 방법의 일환으로 충전재 변화에 따른 PET 재활용 폴리머콘크리트의 황산에 의한 침식 실험을 실시하였다. 실험 결과 충전재로 중탄산칼슘을 사용한 경우는 외형 및 표면 상태에서 부식의 흔적이 있었으며, 중량 변화 및 강도 변화에서도 장기간 부식 환경에 노출 될 경우 문제점을 야기할 수 있음을 확인할 수 있었다. 반면에 충전재로 플라이애쉬를 사용한 경우는 중량변화 및 강도 변화가 적었으며 외형에서도 침지하지 않은 실험체와 거의 변화가 없었다. 이것은 플라이애쉬의 입자의 밀실 충전효과와, 강한 유리질결정체로 구성된 입자 때문인 것으로 판단된다. 따라서, 하수관거, 공장 폐수시설등 부식 환경 하에서의 구조물에서는 플라이애쉬를 충전재로 사용한 폴리머콘크리트의 사용이 적절한 것으로 나타났다.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.33-39
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• 2021

세계적으로 리사이클 원사 분야의 관심과 수요가 급격히 높아짐에 따라, 국내 기업들 또한 리사이클 원사에 대한 연구 개발 및 사업을 촉진중이다. 국내 리사이클 폴리에스터 원사 사업을 주도하고 있는 A사와 B사의 버진 PET와 리사이클 PET 시료 4종을 적외선 분광기 (FT-IR)를 통해 화학적 특성을 확인 하였으며, 시차주사열량계 (DSC)를 통해 열적 특성을 확인하였다. 두 업체의 버진 PET와 리사이클 PET를 비교한 결과, FT-IR에서 두 회사의 제품 모두 PET의 전형적인 스펙트럼을 보여줌과 동시에, 872 cm-1에서 스펙트럼의 차이를 보여주었고, DSC를 통해 리사이클 PET의 융점 및 결정화 온도가 버진 PET에 비해 더 낮은 것을 확인할 수 있었다. 이 결과는 리사이클 PET에 소량 존재하는 오염물질이 PET 원사의 열적 특성에 영향을 주는 중요한 매개 변수임을 보여준다. 총 7회의 가열 및 냉각 과정을 거친 DSC 결과에서, 4개의 샘플 모두 사이클 횟수가 늘어날수록 낮은 융점 및 결정화 온도를 낮은 열유속 세기와 함께 보여주며, 용융 및 결정화 엔탈피의 결과 또한 비슷한 양상을 보여주었다.