• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.78-86
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• 2014

Since cellulose nanofibrils (CNF) has large specific surface area and high water holding capacity, it is very difficult task to remove water from the CNF suspension. However, dewatering of CNF suspension is a prerequisite of following processes such as mat forming and drying for the application of CNF. In this study, we evaluated the drainage of cellulose fibers suspension under vacuum and pressure conditions depending on the number of grinding passes. Also, the effect of the addition of cationic polyelectrolyte on dewatering ability of CNF suspension was investigated. Regardless of dewatering condition, the total drained water amount as well as the drainage rate were decreased with an increase in the number of grinding passes. Pressure dewatering equipment enables us to prepare wet CNF mat with relatively higher grammage. The cationic polyelectrolytes improved the dewatering ability of CNF suspension by controlling the zeta potential of CNF. The fast drainage was obtained when CNF suspension had around neutral zeta potential.

• Membrane Journal
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• v.32 no.6
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• pp.383-389
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• 2022

Membrane separation process is an important technique utilized for various applications. This separation process proceeds due to a driving force such as concentration gradient, pressure or electrical potential gradient etc. Pervaporation is one of the separation process based on solution-diffusion mechanism. The pressure of the permeate side is reduced by creating vacuum and separation is driven due to pressure difference. Purity of the fuel or chemical like ethanol or isopropyl alcohol are improved by dehydration process through porous zeolite membrane. These membranes have high thermal, chemical, mechanical stability. This review is classified mainly into two different sections: Ethanol and bio-oil dehydration by zeolite membrane.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.5-12
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• 2014

Anaerobic digestion was investigated for the stabilization of sludge, decrease of volatile solids, production of biogas for wastewater sludge. In this study, total solids and volatile solids, elemental analysis were conducted to determine characteristics of various types of sludges and investigate the feasibility of biogas production of Municipal Wastewater Sludge (MWS), Industrial Wastewater Sludge (IWS), mixed sludge (Mix), and Municipal Wastewater Sludg Cake (MWSC). Total solids, volatile solids, and C/N ratio were determined in the range of 11.2~20.6 %, 62.1~83.1 % of TS and 4.96~8.33 %. Using the biochemical methane potential (BMP test), mixed sludge and wastewater sludge finished the methane production within approximately 20 day and 16~17 day. Sludge cake finished within 10 day. Mixed sludge produced 395.5 mL $CH_4$ per g of Volatile Solid (VS) and resulted in the highest methane production. For carbon dioxide production, five sludges had similar value of accumulated carbon dioxide production except for sludge cake.

• Membrane Journal
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• v.16 no.3
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• pp.182-187
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• 2006

The purpose of this study was to investigate effect of coagulation on filtration performance of membrane in submerged MBR system and influence of continuous aeration to reduce fouling of membrane surface on coagulated floc. For this purpose, aeration tank sludge of MBR system was compared with jar-test sludge. The experimental results were analysed in terms of floc size and SRF (Specific resistance of Filtration). The more alum was added, the more content of floc below $10{\mu}m$ reduced and SRF decreased. But compared with jar-test results, it was found that effect of coagulation on MBR floc was reduced. Operation time of membrane in alum added MBR was longer than that in control MBR. But operation time was not proportional to alum dose. It was thought that the result was reason that floc below $10{\mu}m$ was not reduced sufficiently by shear force of continuous aeration. Moreover it was founded that if alum is added more than proper dose, it brings filtration resistance to increase.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.47-55
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• 2017

The technology for hydrothermal reaction of organic waste is one of the promising process to improve energy efficiency of biomass waste recycling system since moisture contents of treated biomass could be reduced at 40% or less than by dehydration processes. For these reasons, many parts of the world are interested in hydrothermal reaction of organic waste. In this paper, drying performances were evaluated with and without hydrothermal reaction of organic wastes which are sewage sludge and food wastes. For the hydrothermal reaction, organic wastes were treated at $200^{\circ}C$ for 1hr. Drying time of treated organic waste by hydrothermal reaction was reduced. In case of food waste drying at $100^{\circ}C$, drying time of treated wasted was reduced more 52.9% than non-treated. Hence, drying performances of sewage sludge and food wastes should be improved by hydrothermal reaction. Drying rates of treated wastes were considerably increased at preheat period of drying characteristic curve as followings; at $80^{\circ}C$ sludge as 148%, $100^{\circ}C$ sewage sludge as 151%, $80^{\circ}C$ food waste as 209%, $100^{\circ}C$ food waste as 366%. It means the surface area of treated wastes could be increased with destruction of cell membrane by hydrothermal reaction. However, the designer and operator of drying process should be careful, since enhanced drying rate cause the extension the decreasing drying period.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.756-762
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• 2013

The economical feasibility was conducted to find the adequate method to treat the dredged sediments from agricultural reservoirs in a pilot project that had been operated to improve the quality of water and benthic environments by dredging of contaminated sediments. For benefit/cost (B/C) analysis, the net expenses were considered as the costs of project, and the benefits were calculated from the saving of waste-treatment cost through reuse of dredged sediment, the saving of construction cost of settling pond, and the values of retained water by dredging. Although the economic feasibility depended on the sites of operation, the average B/C value of the pilot project was estimated as 1.32, indicating this project is economically feasible. Depending on the treatment methods, the B/C values were in the order of the methods of coagulating sedimentation, machinery dewatering, stabilization through exothermic reaction, and soil improvement and stabilization. The machinery dewatering method is estimated as the most adequate one to treat the dredged sediments because of the minimum riskiness of secondary pollution, the recyclability, and its economic feasibility.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.419-426
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• 2012

Fresh concrete has 10~20% extra water in it. As those water remain entrapped air in the concrete, life span of structures is reduced. For that reason, if extra water is eliminated, it will be useful to improve the durability of the structures. Though there were many reports about permeable formwork, the study on the properties of permeable liner itself has been insufficient. In addition, making holes on the form causes lowering of workability. Therefore, this study reviewed the properties of woven and non-woven permeable liner and formwork which has no holes on the form. For the woven and non-woven permeable liner, they showed great application with W/C decrease, lowering roughness, increased compressive strength of surface area and slight loss of cement paste, when the were applied to concrete. In addition, they showed different performance according to the density of woven liner or thickness of non-woven liner. Furthermore, when using the draining non-woven permeable liner which has drainage path inside, concrete surface showed required performance with high workability, without drilling the holes on the form.

• Proceedings of the Turfgrass Society of Korea Conference
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• 2011.02a
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• pp.25-32
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• 2011

본 연구는 화력발전의 부산물로 발생하는 석탄바닥재가 골프장 사질 토양의 개량재로 사용 적합한지를 평가하기 위해 수행되었으며, 결과를 요약하면 다음과 같다. 1. 석탄바닥재의 화학성을 분석한 결과 총질소 0.34%, 가용성 인산 $52mgL^{-1}$, 치환성 칼륨 $51mgL^{-1}$ 뿐만 아니라 소량의 치환성 칼슘과 마그네슘을 함유하고 있어 식물생육에 이롭고, 유해중금속함량은 Cd, $Cr^{6+}$, Pb, Ni, As는 $1mgL^{-1}$ 이하, Cu 농도는 $1.25mgL^{-1}$ 검출되어 토양환경보전법의 토양오염우려기준 이하이므로 석탄바닥재 재활용으로 인한 토양오염 가능성은 매우 낮은 것으로 판단된다. 2. 모래 토양에 석탄바닥재를 부피비로 0~50% 비율로 혼합한 시료의 투수계수와 유효수분함량을 측정한 결과 석탄바닥재 혼합비율이 증가할수록 투수계수는 유의성 있게 감소하고 유효수분함량은 유의성 있게 증가해 석탄바닥재가 모래 토양의 낮은 수분보유력을 개선하는 효과가 있음을 확인하였다. 3. 모래 토양에 석탄바닥재를 부피비로 0~50% 비율로 혼합한 시료를 잔디식재층으로 조성한 라이시미터에 잔디종자 파종 후 약 4개월 뒤 잔디밀도가 완전히 형성된 후에 시비 후 3일 간격으로 채취한 용탈수를 분석한 결과 1일과 4일 후에 채취한 초기 용탈수에서는 석탄바닥재 혼합비율이 높을수록 $NO_3-N$, $NH_4-N$ 및 K함량이 유의성 있게 감소했으며, 대조구에 비해 석탄바닥재 혼합비율이 높은 처리구일수록 $NO_3-N$, $NH_4-N$ 및 K함량이 용탈수 채취기간 동안 지속적으로 용탈되었다. 이 결과로 석탄바닥재가 모래 토양의 낮은 양분 보유력을 개선하는데 효과적이고 석탄바닥재처리가 대조구에 비해 오랫동안 식물 생육에 필요한 양분을 공급하는 효과가 있음을 확인하였다. 4. 골프장 그린상구조와 동일한 시험포장을 만들고 모래 토양에 석탄바닥재 10%와 20% 그리고 피트, 액시스, 이소라이트를 부피비로 10% 비율로 혼합한 시료를 잔디식재층으로 조성하고 크리핑 벤트그래스(Agrostis paulstris Huds), Penn A-4 $10gm^{-2}$을 파종한 후에 처리구별로 잔디 품질을 평가하기 위해 잔디 밀도, 뿌리길이, 색상 및 시각적 품질을 조사한 결과 석탄바닥재 처리구는 기존에 사용하는 개량제인 피트, 액시스, 이소라이트 처리구와 동등한 잔디생육 촉진 효과가 있는 것으로 조사되었다. 5. 결론적으로 석탄바닥재는 골프장 토양의 물리적 특성과 화학적 특성을 개선하고 잔디생육에 필요한 양분을 공급하는데 효과적인 토양개량재라고 할 수 있다.

• The Journal of the Korea Contents Association
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• v.8 no.10
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• pp.301-308
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• 2008

The purpose of this study was to investigate the change of physical fitness, MDA, SOD after short-term weight reduction through exercise, food restriction and exhalation of sweat among Taekwondo players. The subjects ten male collage Taekwondo players with excellent practical skills, and more than seven years of experiences. They were asked to reduce about 5% of their body weight in seven days. Physical fitness levels were analyzed through grip strength, muscle endurance, flexibility, power, agility, balance, reaction time and MDA and SOD through blood test. The results of this study were as follows; First, there was no significant change in physical fitness due to short-term weight reduction in muscle strength, muscle endurance, flexibility, power, agility, balance and reaction time. Second, The change of MDA and SOD, resulting from short-term weight reduction did not show significant difference statistically. Therefore, the results of this study indicate that the Taekwondo players' short-term weight reduction of 5% of their body weight did not influence on their athletic performance and physiological capacity. Therefore athletes and coaches should endeavor to take exercise, dietary, and dehydration into consideration when conducting 5% of their body weight reduction in a week.

• Journal of Convergence for Information Technology
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• v.10 no.6
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• pp.77-86
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• 2020

A thin and porous non-flammable wiper was prepared by phosphorus acid solution treatment and subsequent oven annealing. The H₃PO₃ treatment improved flame retardancy of wiper paper to nonflammable level. Thermogravimetric analyses showed that residues increased to 50% at 700℃, which means this treatment helps dehydration of the cellulose chain and promotes the formation of char-like structures during the burning. FT-IR and X-ray photoelectron spectroscopy showed that some of the added H₃PO₃ could react with the functional groups of the cellulose chain. The reacted H₃PO₃ components promote dehydration of the cellulose components and the formation of a char-like structure and improve the flame retardancy of the wiper paper.