• Environmental Engineering Research
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• 제24권2호
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• pp.354-361
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• 2019

Renewable energy from biomass and biodegradable wastes can significantly supplement the global energy demand if properly harnessed. Pyrolysis is the most profound modern technique that has proved effective and efficient in the energy conversion of biomass to yield various products like bio-oil, biochar, and syngas. This study focuses on optimization of slow pyrolysis of banana peels waste to yield banana peels vinegar, tar and biochar as bio-infrastructure products. Response surface methodology using central composite design was used to determine the optimum conditions for the banana wastes using a batch reactor pyrolysis system. Three factors namely heating temperature ($350-550^{\circ}C$), sample mass (200-800 g) and residence time (45-90 min) were varied with a total of 20 individual experiments. The optimal conditions for wood vinegar yield (48.01%) were $362.6^{\circ}C$, 989.9 g and 104.2 min for peels and biochar yield (30.10%) were $585.9^{\circ}C$, 989.9 g and 104.2 min. The slow pyrolysis showed significant energy conversion efficiencies of about 90% at p-value ${\leq}0.05$. These research findings are of primary importance to Uganda considering the abundant banana wastes amounting to 17.5 million tonnes generated annually, thus using them as pyrolysis feedstock can boost the country's energy status.

• Asian-Australasian Journal of Animal Sciences
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• 제18권8호
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• pp.1098-1104
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• 2005

The trial was carried out on twenty-one Friesian cows at the end of eight months gestation, nine multiparous and twelve primiparous; allocated into three groups (1 control, 2 and 3 experimental). The same diet was administred to all three groups before partum (12.8 kg DM/head/day) and after partum (18.8 kg DM/head/day). The cows in groups 2 and 3 received two different daily quantities of amino-acid chelated chromium (0.6 and 1.2 mg Cr/kg DM) from 4 weeks prior to presumed parturition to 6 weeks after. The milk yield control was carried out at 15, 30, 42 and 60 days. All animals were immunised two weeks prior to the presumed parturition and two weeks after with the following antigens: ovalbumin and brucellergene. Blood samples were collected weekly to monitor humoral and cell-mediated immune responses. When analysing the results of antibody immunity (ovalbumin) in the sixth blood collection both treated groups significantly increased compared to group 1 (0.5230 and 0.4536 vs. 0.1812 OD; p<0.05). The results of the cell-mediated immune response (brucellergene) had significant differences (p<0.10) in correspondence to the third (between group 2 and control) and the fifth (between groups 3 and 2) blood collection. Significant differences in fat corrected milk were observed at 42 days between group 3 and the other two groups (31.01 vs. 26.99 and 28.66 kg/d, p<0.05) and at 60 days between group 3 and control (30.88 vs. 26.69 kg/d, p<0.05). Before partum and at partum a positive immune response was obtained with a lower dose of chromium. After partum a positive immune response, anti-OVA indicator, was obtained with the higher dose of chromium while, $\gamma$-IFN indicator, with the lower dose. A significant increase of the milk yield resulted at both 42 and 60 days with the highest level of chromium.

• 한국작물학회지
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• 제51권7호
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• pp.571-583
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• 2006

안정적인 고품질 쌀의 생산을 위한 수비처방을 하기 위해서는 유수형성기 생육상태와 질소영양상태별 질소시비량에 따른 수량반응에 대한 이해가 있어야만 한다. 따라서 본 연구는 기비와 분얼비 시용량을 달리하여 유수분화기에 다양하게 조성된 벼 생육 및 질소영양상태별로 수비 질소 시용량을 달리하였을 때의 수량반응을 질소시비량과 질소흡수량으로 살펴봄으로써 수비처방에 필요한 기초 자료를 얻고자 하였다. 1. 기비 + 분얼비와 수비 시용량 간에는 유의한 상호작용이 없어 수비 시용량에 관계없이 기비 + 분얼비가 증가할수록 그리고 기비 + 분얼비 시용량에 관계없이 수비 시용량이 증가할수록 수량은 증가하는 경향이었다. 2. 영양생장기 시비량(기비 + 분얼비)이 $10{\sim}12\;kgN/10a$까지 생식생장기 시비량(수비)이 6 kgN/10a까지 증가할수록, 그리고 영양생장기 질소흡수량이 $6{\sim}7\;kgN/10a$까지 생식생장기 질소흡수량이 $5{\sim}6\;kgN/10a$까지 수량은 직선적으로 유의하게 증가하는 경향이었으나 그 이상일 경우 수량 증가폭은 점차 줄어들었는데, 이는 등숙률과 천립중이 크게 감소하기 때문이었다. 3. 단위질소흡수량당(kgN/10a) 총영화수($/m^{2}$) 증가는 영양생장기가 약 1900여개, 생식생장기가 $1400{\sim}1500$여개였지만 단위질소흡수량당 수량증가(kg/10a)는 영양생장기가 $30{\sim}50$, 생식생장기가 $40{\sim}80$ 정도였다. 4. 총영화수는 출수기 질소흡수량과 직선적인 관계를 보이고 수량은 시기별 질소흡수량의 다과에 상관없이 이들의 총합인 수확기 질소함량과 2차 곡선관계($R^2$>0.88)를 보였는데, 이는 어느 시기에 질소를 흡수하느냐보다는 생육기간의 총질소흡수량에 의해 수량이 좌우되는 것으로 볼 수 있다. 또한 질소흡수량이 같더라도 총영화수와 수량은 연차간에 차이를 보였다.

• Environmental Engineering Research
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• 제22권1호
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• pp.19-30
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• 2017

Direct catalysis of vapors from vacuum pyrolysis of biomass was performed on MCM-41 to investigate the effects of operating parameters including catalyzing temperature, catalyzing bed height and system pressure on the organic yields. Optimization of organic phase yield was further conducted by employing response surface methodology. The statistical analysis showed that operating parameters have significant effects on the organic phase yield. The organic phase yield first increases and then decreases as catalyzing temperature and catalyzing bed height increase, and decreases as system pressure increases. The optimal conditions for the maximum organic phase yield were obtained at catalyzing temperature of $502.7^{\circ}C$, catalyzing bed height of 2.74 cm and system pressure of 6.83 kPa, the organic phase yield amounts to 15.84% which is quite close to the predicted value 16.19%. The H/C, O/C molar ratios (dry basis), density, pH value, kinematic viscosity and high heat value of the organic phase obtained at optimal conditions were 1.287, 0.174, $0.98g/cm^3$, 5.12, $5.87mm^2/s$ and 33.08 MJ/kg, respectively. Organic product compositions were examined using gas chromatography/mass spectrometry and the analysis showed that the content of oxygenated aromatics in organic phase had decreased and hydrocarbons had increased, and the hydrocarbons in organic phase were mainly aliphatic hydrocarbons. Besides, thermo-gravimetric analysis of the MCM-41 zeolite was conducted within air atmosphere and the results showed that when the catalyst continuously works over 100 min, the index of physicochemical properties of bio-oil decreases gradually from 1.15 to 0.45, suggesting that the refined bio-oil significantly deteriorates. Meanwhile, the coke deposition of catalyst increases from 4.97% to 14.81%, which suggests that the catalytic activity significantly decreases till the catalyst completely looses its activity.

• 한국지반환경공학회 논문집
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• 제18권3호
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• pp.25-30
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• 2017

본 논문에서는 변형률 응답 곡선의 형상을 정량적으로 분석하는 새로운 기법을 소개하였다. 변형률 응답 곡선은 응력 공간에서 단위 응력을 입력하였을 때의 발생한 변형률을 변형률 공간에 작성한 이미지이다. 변형률 응답 곡선의 형상 변화 특성을 퓨리에 기술자를 이용하여 분석하였으며, 탄소성 모델 기반으로 그 의미를 해석하였다. 전산해석결과 응력 경로가 항복면 내부에 머물러 탄성 변형만 존재할 경우, 퓨리에 기술자는 일정하게 그 값을 유지하였으나 응력 경로가 항복면에 도달하여 소성변형이 발생하는 순간 퓨리에 기술자는 변화하였다. 불교란 자연 시료와 재성형 시료에 대해 실시한 응력 경로 시험 결과, 자연 시료에 대해서만 응력 경로가 항복면에 도달하였을 때 명확한 변형률 응답 곡선의 형태 변화가 발견되었으며, 퓨리에 기술자 값도 명확하게 변화하였다. 퓨리에 기술자 중, 비대칭성과 관련 있는 퓨리에 기술자 값이 항복 및 점성토 구조변화의 지표로 활용할 수 있는 것을 확인하였다.

• Geomechanics and Engineering
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• 제25권4호
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• pp.341-345
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• 2021

1D sand compression response to ko-loading experiences volume contraction from low to high effective stress regimes. Previous study suggested compressibility model with physically correct asymptotic void ratios at low and high stress levels and examined only for both remolded clays and natural clays. This study extends the validity of Enhanced Terzaghi model for different sand types complied from 1D compression data. The model involved with four parameters can adequately fit 1D sand compression data for a wide stress range. The low stress obtained from fitting parameters helps to identify the initial fabric conditions. In addition, strong correlation between compressibility and the void ratio at low stress facilitates determination of self-consistent fitting parameters. The computed tangent constrained modulus can capture monotonic stiffening effect induced by an increase in effective stress. The magnitude of tangent stiffness during large strain test should not be associated with small strain stiffness values. The use of a single continuous function to capture 1D stress-strain sand response to ko-loading can improve numerical efficiency and systematically quantify the yield stress instead of ad hoc methods.

• 한국환경성돌연변이발암원학회지
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• 제15권2호
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• pp.94-99
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• 1995

The adaptive response and cross-adaptive response to sister chromatid exchanges (SCEs) and DNA single-strand breaks (SSBs) in Chinese hamster ovary (CHO)-K$_1$ cells treated with ultraviolet radiation (UV), ethyl methanesuffonate (EMS), or bleomycin (BLM) were investigated. Two assays were used in this study; SCEs and alkaline elution. The pretreatment with low conditioning dose of 2 mM EMS or 1 J/m$^2$ UV decreased the yield of SCEs induced by subsequent treatment with 8 mM EMS, 5 J/m$^2$ UV or 5 $\mu$g/ml BLM. And the pretreatment with low conditioning dose of 1 $\mu$g/ml BLM decreased the yield of SCEs induced by subsequent treatment with 5 $\mu$g/ml BLM or 5 J/m$^2$ UV. The rejoining of DNA SSBs in cells subsequently treated with 2 J/m$^2$ UV, 50 mM EMS or 400 $\mu$g/ml BLM is higher than that only treated with 2 J/m$^2$ UV, 50 mM EMS or 400 $\mu$g/ml BLM. These results suggest that there are the adaptive response and cross-adaptive response to SCEs, and is the adaptive response to the rejoining of DNA SSBs in CHO cells.

• 한국작물학회지
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• 제51권6호
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• pp.527-533
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• 2006

The response of chickpea (Cicer arietinum L.) to dual inoculation with Rhizobium (R) and arbuscular mycorrhiza (AM), nitrogen (N) and phosphorus (P) was studied on spore abundance and colonization of AM, nodulation, growth, yield attributes and yield. In all the parameters of the crop the performance of Rhizobium inoculant alone was superior to control. Dual inoculation with Rhizobium and AM in presence of P performed the best in recording number of spore $100g^{-1}$ rhizosphere soil and root colonization, number and dry weight of nodule, dry weights of shoot and root, number of pod $plant^{-1}$, number of seed $pod^{-1}$, seed and stover yields of chickpea. The maximum seed yield of 3.33 g $plant^{-1}$ was obtained by inoculating chickpea plants with Rhizobium and AM in association with P. From the view point of nodulation, growth, yield attributes and yield of chickpea, dual inoculation with Rhizobium and AM along with P was considered to be the balanced combination of nutrients for achieving the highest output from cultivation of chickpea in Shallow Red Brown Terrace Soil of Bangladesh.

• 한국환경농학회지
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• 제42권1호
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• pp.63-70
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• 2023

Golden apple snails (Pomacea canaliculat) (GAS) are widely used for weed control in rice cultivation. However, concerns on the ecological risk of invasive GAS species are increasing. This study aimed to evaluate the overall impacts of GAS on weed control, abundance of aquatic animals and insects, and rice yield, in comparison with that from other biocontrol agents such as loach (Misgurnus mizolepis) and catfish (Silurus asotus), which are alternatives for biological weed control in rice paddy cultivation. Field experiments included five treatments; control, herbicide, GAS, loach, and catfish. During the rice growth, weed appearance and biological abundance were monitored, and at harvest, the rice yield was determined. Weed control efficiency was the highest for GAS treatment (100%), followed by that for herbicide (95.8%), loach (57.5%), and catfish treatments (31.7%). Insect abundance was considerably decreased in GAS treatment due to heavy weed removal, which affects the habitat of aquatic animals and insects. The amount of rice yield (unit: kg 10 a^-1) was in the order of GAS (798.9) > loach (708.1) = herbicide (700.7) > catfish (629.4) > control (496.0). Therefore, considering the weed control efficiency, biological abudance, and rice yield, loach could be a potential alternative for biological weed control in organic rice farming. However, the activity of the biocontrol agents are susceptible to environmental conditions; therefore, further studies under different conditions are essential to confirm these findings.

• Earthquakes and Structures
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• 제5권6호
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• pp.657-678
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• 2013

For economical earthquake resistant design of cable-stayed bridge tower, the use of energy dissipation systems for the earthquake protection of steel structures represents an alternative seismic design method where the tower structure could be constructed to dissipate a large amount of earthquake input energy through inelastic deformations in certain positions, which could be easily retrofitted after damage. The design of energy dissipation systems for bridges could be achieved as the result of two conflicting requirements: no damage under serviceability limit state load condition and maximum dissipation under ultimate limit state load condition. A new concept for cable-stayed bridge tower seismic design that incorporates sacrificial link scheme of low yield point steel horizontal beam is introduced to enable the tower frame structure to remain elastic under large seismic excitation. A nonlinear dynamic analysis for the tower model with the proposed energy dissipation systems is carried out and compared to the response obtained for the tower with its original configuration. The improvement in seismic performance of the tower with supplemental passive energy dissipation system has been measured in terms of the reduction achieved in different response quantities. Obtained results show that the proposed energy dissipation system of low yield point steel seismic link could strongly enhance the seismic performance of the tower structure where the tower and the overall bridge demands are significantly reduced. Low yield point steel seismic link effectively reduces the damage of main structural members under earthquake loading as seismic link yield level decreases due their exceptional behavior as well as its ability to undergo early plastic deformations achieving the concentration of inelastic deformation at tower horizontal beam.