• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.271-278
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• 2006

We used polymers of alternating cationic and anionic nature to build up shells on fiber surfaces, strengthen the worn-out fibers and improve paper properties made from such fibers. OCC and ONP pulps were either dipped or salted out in the cationic polyallylamine, polyacrylamide and starch solutions. After centrifugal drying, these were followed by treatments in anionic polyacrylic acid, poly-acrylamide, and starch solutions, respectively. The shell-enhanced fibers were formed into handsheets and their physical properties evaluated. The results show that building multiple shells on worn-out fiber surfaces can strengthen the fibers and paper. The simpler and more practical impregnation-centrifuging treatment provided the desired effects, whereas salting out the polymers produced somewhat superior fibers. The latter process, were impractical, however. The first pair of polymeric shells imparted marked strength improvement, whereas later layers had diminishing efficacies. Overall, the methods can improve fiber quality, attaining paper strength requirements without resorting to expensive measures. Alternate cationic polymer and filler powders were also deposited on fiber surface based on the micriparticle system in an anticipation of stiffness gains. Platy minerals, such as montmorillonite, bentonite, sericite, clay and talc were added following cationic PAM. After dewatering of polymer-pigment shelled fiber of one to 3 pairs of layers, handsheets either calendered or uncalendered were evaluated. The results indicate that regardless of calendaring, stiffness of the handsheets did not improve appreciably while certain other strength properties showed gains. We also attempted the novel starch gel filler addition method wherein tapioca starch and filers (PCC, sericite or clay) were mixed at high solids content of 50% and cooked until gelatinized. The filled handsheets were dried under various conditions and then tested for their properties. Improvements in strengths of modified filled paper were observed.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권3호
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• pp.43-50
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• 2018

In a previous study, the feasibility of four materials (bentonite, steelmaking slag, lime and organic compost) to induce soil aggregate formation was assessed and the mixtures of organic compost and lime were chosen as most effective amendments in terms of cost benefit. This work is a subsequent study to evaluate the effectiveness of those amendments in reducing soil loss in $15^{\circ}$ sloped agricultural area by using rainfall simulation test. Three different soils were treated with two conditions of organic compost/lime mixtures (2% + 2%, 3% + 1%, w/w). In the amended soils, soil fertility was increased due to the increase of CEC, T-N, and T-P. During the rainfall simulation, suspended solid in run-off water from amended soil were reduced by 43% ~ 78%. When the content of organic compost was higher than that of lime, reduction of soil loss was also increased by 67% ~ 78%. Sediment discharge was also decreased by 72% ~ 96% in the amended soil. Similar to the suspended solid analysis, higher organic compost content led to more reduction of soil discharging, which implies organic compost is more effective than lime in reducing soil loss. The overall result suggests that the mixtures of organic compost and lime could be used as amendment materials to reduce soil loss in sloped farmland.

• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.372-380
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• 2018

To abate the problem of odor from restaurants, a hybrid adsorbent consisting of organic and inorganic materials was developed and evaluated using acetaldehyde as a model compound was deveioped and evaluated. Powders of activated carbon, bentonite, and calcium hydroxide were mixed and calcinated to form adsorbent structure. The surface area of the hybrid adsorbent was smaller than that of high-quality activated carbon, but its microscopic image showed that contours and pores were developed on its surface. To determine its adsorption capacity, both batch isotherm and continuous flow column experiments were performed, and these results were compared with those using commercially available activated carbon. The isotherm tests showed that the hybrid adsorbent had a capacity 40 times higher than that of the activated carbon. In addition, the column experiments revealed that breakthrough time of the hybrid adsorbent was 2.5 times longer than that of the activated carbon. These experimental results were fitted to numerical simulations by using a homogeneous surface diffusion model (HSDM); the model estimated that the hybrid adsorbent might be able to remove acetaldehyde at a concentration of 40 ppm for a 5-month period. Since various odor compounds are commonly emitted as a mixture when meat is barbecued, it is necessary to conduct a series of experiments and HSDM simulations under various conditions to obtain design parameters for a full-scale device using the hybrid adsorbent.

• Geomechanics and Engineering
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• 제17권1호
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• pp.31-45
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• 2019

In this study the spatial variability of soils is substantiated physically and numerically by using random field theory. Heterogeneous samples are fabricated by combining nine homogeneous soil clusters that are assumed to be elements of an adopted random field. Homogeneous soils are prepared by mixing different percentages of kaolin and bentonite at water contents equivalent to their respective liquid limits. Comprehensive characteristic laboratory tests were carried out before embarking on direct shear experiments to deduce the basic correlations and properties of nine homogeneous soil clusters that serve to reconstitute the heterogeneous samples. The tests consist of Atterberg limits, and Oedometric and unconfined compression tests. The undrained shear strength of nine soil clusters were measured by the unconfined compression test data, and then correlations were made between the water content and the strength and stiffness of soil samples with different consistency limits. The direct shear strength of heterogeneous samples of different stochastic properties was then evaluated by physical and numerical modelling using FISH code programming in finite difference software of $FLAC^{3D}$. The results of the experimental and stochastic numerical analyses were then compared. The deviation of numerical simulations from direct shear load-displacement profiles taken from different sources were discussed, potential sources of error was introduced and elaborated. This study was primarily to explain the mathematical and physical procedures of sample preparation in stochastic soil mechanics. It can be extended to different problems and applications in geotechnical engineering discipline to take in to account the variability of strength and deformation parameters.

• 한국지반환경공학회 논문집
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• 제12권5호
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• pp.5-12
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• 2011

지반공학적으로 흙의 함수비는 흙의 역학적 거동특성을 예측할 수 있는 중요한 인자이다. 통례적으로 흙의 함수비는 $105^{\circ}C$ 건조로에서 16~24시간 동안 건조해 함수비 값을 구한다. 현재 이러한 방법은 가장 보편적인 방법이며 많은 실험 데이타가 축척되어 있으나, 동시에 현장에서 사용하기에는 많은 시간을 필요로 하고 문제 발생 시 신속한 대책마련이 어렵다는 단점이 있다. 최근 이러한 문제점을 보완하기 위해서 외국의 실험규정(ASTM, JGS)에서는 microwave oven을 이용한 함수비 측정법이 제정되어 있다. 또한 microwave oven에 의한 함수비의 신뢰성 평가에 관한 연구도 많이 이루어지고 있다. 본 연구에서는 주문진표준사, 카올리나이트, 벤토나이트, 화강풍화토, 유기토 등을 대상으로 microwave oven을 이용한 함수비 측정방법의 타당성을 확인했다. 신뢰성에 영향을 미치는 인자에 대해서 분석하고 신뢰성을 높이기 위한 방법에 대해서 고찰하였다.

• Animal Bioscience
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• 제34권3_spc호
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• pp.405-416
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• 2021

Objective: This study evaluated the effects of feeding diets naturally contaminated with deoxynivalenol (supplemental 2 mg/kg) on health, growth, and the effects of a mycotoxin-detoxifying additive in newly-weaned pigs. Methods: Thirty-six pigs (27 day-old) were housed individually and assigned to 3 treatments for 5 weeks: CON (diet containing minimal deoxynivalenol), MT (diet with supplemental 1.9 mg/kg of deoxynivalenol), and MT+D (MT + mycotoxin-detoxifying additive, 0.2%, MegaFix, ICC, São Paulo, Brazil). The mycotoxin-detoxifying additive included bentonite, algae, enzymes, and yeast. Blood was taken at week 2 and 5. Jejunal tissue were taken at week 5. Data were analyzed using the MIXED procedure of SAS. Results: Pigs fed MT+D tended to have decreased (p = 0.056) averaged daily feed intake during week 1 than MT. At week 2, serum aspartate aminotransferase/alanine aminotransferase in MT tended to be lower (p = 0.059) than CON, whereas it was increased (p<0.05) for MT+D than MT, indicating hepatic damages in MT and recovery in MT+D. Pigs fed MT had lower (p<0.05) blood urea nitrogen/creatinine than CON, supporting hepatic damage. At week 5, pigs fed MT tended to have reduced (p = 0.079) glucose than CON, whereas it was increased (p<0.05) for MT+D than MT, indicating impaired intestinal glucose absorption in MT, which was improved in MT+D. Pigs fed CON tended to have increased (p = 0.057) total glutathione in jejunum than MT, indicating oxidative stress in MT. Pigs fed MT+D had a reduced (p<0.05) proportion of Ki-67-positive cells in jejunum than MT, indicating lower enterocyte proliferation in MT+D. Conclusion: Feeding supplemental 1.9 mg/kg of deoxynivalenol reduced growth and debilitated hepatic health of pigs, as seen in leakage of hepatic enzymes, impaired nitrogen metabolism, and increase in oxidative stress. The mycotoxin-detoxifying enhanced hepatic health and glucose levels, and attenuated gut damage in pigs fed deoxynivalenol contaminated diets.

• 한국지반공학회논문집
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• 제23권2호
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• pp.29-34
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• 2007

본 연구에서는 카올린광물과 벤토나이트로 혼합물에 대한 열처리의 영향을 조사하였다. $100^{\circ}C$에서 $500^{\circ}C$까지 $100^{\circ}C$씩 온도를 증가시켜 인공적으로 생성한 혼합점토시료에 대하여, 열처리에 따른 건설재료의 강도특성을 분석코자 액성한계와 소성한계의 변화를 조사하였다. 실험 결과, 액성한계는 $100^{\circ}C$에서 $300^{\circ}C$ 사이에서는 약간 감소하는 경향을 나타내었으며, $300^{\circ}C$ 이후에는 액성한계가 급격히 감소하였다. 반면, 소성한계는 열처리의 영향이 크지 않았으며, $500^{\circ}C$로 처리한 혼합점토시료 모두에서 비소성(N.P.)을 나타내었다. 열처리에 따른 NaCl 함유량은 열처리 온도가 증가함에 따라 감소하는 것으로 나타났으며, 수소이온농도(pH) 역시 열처리의 크게 영향을 받는 것으로 나타났다. 양이온교환능력(C.E.C.) 또한, 열처리 온도에 따라 감소하는 경향을 보여 열처리에 따라 혼합점토의 액 소성한계가 영향을 크게 받는 것으로 나타났다.

• 멤브레인
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• 제32권1호
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• pp.66-73
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• 2022

본 연구에서는 stainless steel로 재질로 된 금속평막모듈을 이용하여 고플럭스가 유지되면서 처리수의 안정화 방안을 모색하였다. 이 모듈은 기공사이즈가 13 ㎛ 단위여서 플럭스가 60 LMH에서 100 LMH까지 고플럭스로 운전이 가능하다 그러나 SS가 초기 운전 시 30~50 ppm 정도 유출되지만 SS가 응집핵으로 작용하므로 응집이 가능하게 된다. 기존 고분자막 여과수는 응집핵이 없어서 coagulation은 되지만 floculation이 안되므로 추가적으로 응집보조제인 clay나 벤토나이트를 투여하게 되는데 본 연구에서는 이런 응집보조제 필요 없이 SS 누출만으로 floculation이 되므로 총인처리와 처리수질이 안정성을 도모하고자 하였다. 최종적으로 안정적인 처리수에 고플럭스가 가능한 Metal필터 운전이 MBR 시스템에서 적용가능한지 타당성을 연구하고자 하였다.

• 터널과지하공간
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• 제34권1호
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• pp.71-87
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• 2024

고준위방사성폐기물 심층처분 시, 처분공 주변의 근계암반은 높은 지중응력과 재포화된 벤토나이트 완충재의 팽윤압, 방사성 원소 붕괴열의 영향을 받아 국부적으로 투수계수가 변화될 수 있다. 본 연구에서는 국내 유력한 처분 대상 부지 암종 중의 하나인 결정질 경암으로서의 화강암을 대상으로, 실제 처분 환경에서 예상되는 다양한 구속압과 온도 조건을 적용하여 투수계수 변화 특성을 실험적인 방법을 통하여 고찰하고자 하였다. KURT 화강암 시험편 하나당 3개 이상의 정수압 조건에서 투수시험을 수행하여 구속압이 증가함에 따라 투수계수가 지수적으로 감소하는 관계를 도출하였다. 예상 최대 온도로 설정한 90℃ 이하 수준에서는 온도에 의한 투수계수 변화가 무시 가능할 정도로 작음을 확인하였다. 추가로 초기투수계수가 초기공극률의 거듭제곱에 비례하는 상관관계를 도출함으로써, 특정 공극률을 지닌 화강암이 일정 구속압 하에 있을 때 가지는 투수계수 값을 유추할 수 있었다.

• 한국지반신소재학회논문집
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• 제23권1호
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• pp.1-7
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• 2024

본 연구에서는 지중 내 오염물질(TPH, Phenol)의 확산 방지를 위해 오염 발생시에만 선택적으로 차수성능을 발현하는 차수재를 제조하고자 하였다. 선택적차수재의 구성물질로는 주문진규사, 벤토나이트, 폴리올레핀 엘라스토머, 스필하운드 마린을 사용하였으며, 본 연구에서는 구성물질들의 활용가능성을 평가하기 위해 기초 특성 및 환경유해성을 확인하였으며 오염물질과의 접촉 24시간 후 변화되는 투수특성을 비교하여 차수재로서 사용가능성을 확인하였다. 각 구성물질의 pH는 일반 지하수 pH 범위와 유사하였으며 독성특성 및 유해물질 용출가능성 분석결과 기준치 이하의 함량을 보여 환경유해성은 없다고 판단되었다. 또한 오염물질 접촉 전‧후 투수계수를 비교하였을 때, 접촉 전 α × 10^-3cm/sec 내외의 투수계수가 오염물질과 접촉 이후 α × 10^-6cm/sec로 감소된 결과를 보여 차수재의 비오염 상황에서는 투수성과 오염발생시 차수성능 발현을 확인할 수 있었다.