• Korean Membrane Journal
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• 제6권1호
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• pp.37-43
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• 2004

Comb-type graft hydrogels composed of alginate and poly(N-isopropylacrylamide) (PNIPAAm) were prepared to manifest rapid temperature and pH sensitivity. To appear the electro-sensitivity, the polyaniline, conducting polymer, was added into the matrix. The swelling kinetics and ratios were compared under the various compositions of polyaniline. The swelling behaviors revealed that conducting polymer/hydrogel composites could control the swelling ratio and kinetics. The addition of polyaniline in the matrix improved the thermal stability in comparison with that of the hydrogel without polyaniline. In temperature sensitivity, the adding the polyaniline into the matrix decreased the degree of change in the swelling ratio. The swelling ratios continuously increased with increasing pH values. The drug release rate from the hydrogel increased with the adding the polyaniline and the applying the direct voltage to the hydrogels.

• 천문학회지
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• 제23권1호
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• pp.71-82
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• 1990

Theoretical calculations of the combined radiative transfer and statistical equilibrium equation including the charge-particle conservations have been earned out for a multilevel hydrogen atom in quiescent prominences. Cool and dense models show the steep changes of population and radiation field in the vicinity of the surface, while these physical quantities remain unchanged for models with temperature of 7,300K, regardless of total densities. Ionization rate of hydrogen atom related with metallic line formation varies in considerable amounts from the surface to the center of model prominences cooler than 6,300K. However, such cool models cannot release enough hydrogen line emissions to explain observed intensities. Prominence models with a temperature higher than 8,000K can yield the centrally reversed Lyman line profiles confirmed by satellite EUV observations. We find that queiscent prominence with a density between $2{\times}10^{11}$ and $10^{12}cm^{-3}$ should be in temperature range between 6,300K and 8,300K, in order to explain consistently observed H alpha, beta line emissions and $n_p/n_l$ ratio.

• Elastomers and Composites
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• 제39권2호
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• pp.105-120
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• 2004

본 연구에서는 금속수산화물과 다양한 인계 난연제를 포함한 난연 acrylonitrile-butadiene rubber (NBR) 발포체를 제조하고, 이때 인 함유량에 따른 열적특성. 난연특성, 발포특성 등의 변화 및 이들의 상관관계를 조사하였다. NBR 발포체의 발포특성 및 모폴로지 분석 결과 인/질소계 난연제 10 phr 범위 내에서 대체적으로 인/질소계 난연제를 투입하지 않은 금속수산화물만을 사용한 경우와 유사한 발포특성 및 모폴로지를 가짐을 알 수 있었다. 열 분석에서는 인 함유량이 많은 인/질소계 난연제를 사용할 경우 화염분위기 하에서의 char 형성과 관련한 잔류량이 많아짐으로써 난연성이 향상됨을, LOI 분석에서도 인 함유량이 증가함에 따라 LOI가 증가함을 알 수 있었다. cone-calorimeter 분석 결과 열 및 LOI 분석 결과와 유사한 경향성을, 인 함유량이 증가함에 따라 HRR, THR, EHC 등이 감소하는 반면에 COY는 증가함을, 즉 난연성이 상승함을 확인할 수 있었다. 연기밀도 분석 결과 cone-calorimeter 분석에서의 (A)-COY와 같은 경향성을 보여주었다.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.301-311
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• 2018

In this study, the ion-gelation method was applied to fabricate novel Fe-carbon-bentonite-alginate beads ($Fe^0$/C-BABs). $Fe^0$/C-BABs could effectively control Fe release during persulfate (PS) activation in N-acetyl-p-aminophenol (APAP) oxidation. A novel two-stage approach that combined $Fe^0$/C-BABs and an oyster-shell-filled bed (OSFB) column was developed to address the low pH and high Fe concentration of the effluent of the traditional PS process. The application of the $Fe^0$/C-BABs and OSFB column regulated pH levels and Fe release during the advanced oxidation of APAP. The characteristics of $Fe^0$/C-BABs were also investigated through scanning electron microscopy, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. The long-term operation performance of $Fe^0$/C-BABs in a continuous fixed-bed reactor under simultaneous PS and APAP feeding was also evaluated. The effects of initial PS concentration, pH, fixed-bed weight, in-flow rate, and dissolved oxygen (DO) were investigated. Under selected conditions, 86.3% efficiency was achieved during the first stage of APAP degradation (effluent pH of 3.05, Fe contents: $106.25mgL^{-1}$). Water quality improved after the effluent was passed through the OSFB column (effluent pH of 6.32, Fe contents: $21.43mgL^{-1}$). Moreover, this study analyzed the free radicals and intermediates produced during APAP degradation to identify the possible routes of APAP degradation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.320-325
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• 2003

Acoustic-Pressure Response of diluted hydrogen-air diffusion flames is investigated numerically by adopting a fully unsteady analysis of flame structures. In the low-pressure regime, the amplification index remains low and constant at low frequencies. As acoustic frequency increases, finite-rate chemistry is enhanced through a nonlinear accumulation of heat release rate, leading to a high amplification index. Finally, the flame responses decrease at high frequency due to the response lag of the transport zone. For a medium-pressure operation and low-frequency excitation, the amplification index is low and constant. It then decreases at moderate frequencies. As frequency increases further, the amplification index increases appreciably due to an intense accumulation effect.

• 한국철도학회논문집
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• 제11권1호
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• pp.7-12
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• 2008

본 연구에서는 경사각에 다른 임계속도 변화를 파악하기 위하여 축소모형 실험을 수행하였다. Froude 상사를 사용하여 1/20 축소모델 시험을 수행하였고, 화원은 메탄올, 아세톤, 헵탄을 연료로하여 Akinson과 Wu가 사용한 가스버너가 아닌 배연속도에 따라 달라지는 정사각형 풀을 사용하였으며, 터널의 각도는 $0^{\circ}$, $2^{\circ}$, $4^{\circ}$, $6^{\circ}$, $8^{\circ}$에 관하여 실험을 수행하였다. 발열량과 온도는 로드셀과 K-type 열전대를 사용하여 측정하였다. 실험결과 발열량 변화를 고려하지 않은 Atkinson과 Wu의 실험결과 보다 배연속도에 따른 발열량이 변화하는 풀화재를 사용한 경우가 더 큰 기울기 값을 얻었다. 따라서 배연속도는 화원의 연소율 변화에 직접적으로 영향을 미치기 때문에 경사터널화재 발생시 연소율의 변화에 따른 임계속도의 영향을 고려하는 것이 중요하다.

• 한국토양비료학회지
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• 제39권5호
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• pp.292-297
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• 2006

호남평야지에서 건답직파 조기파종재배에 알맞은 완효성복합비료 시용량을 구명하고자 '97~'98년에 호남농업시험장 수도포장인 전북통(미사질양토)에서 동진벼를 공시하여 시험한 결과를 요약하면 다음과 같다. 토양의 암모니아태 질소는 유수형성기까지는 관행시비보다 모든 완효성비료 시비에서 많았고 완효성비료 시용량이 많을수록 많았으나 출수기에는 이삭거름시용으로 관행시비가 완효성비료보다 많았다. 초장은 최고 분얼기까지는 관행시비보다 완효성비료시비에서 길었으나 간장은 완효성비료 100%시용을 제외하고는 관행시비와 같거나 짧았다. 경수와 수수는 모든 생육시기에서 관행시비보다 완효성비료시용에서 많았고 완효성비료 시용량이 많을수록 많았으나 유효경비율은 정수 및 수수와 반대의 경향이었다. 질소 이용율은 관행시비보다 완효성비료시용에서 높았고 완효성비료 시용량이 많을수록 감소되는 경향이었다. 단위면적당 입수는 관행시비보다 완효성비료를 증시할수록 많았으나 현미 천립중은 단위면적당 입수와 반대의 경향이었다. 쌀 수량은 완효성비료 60% 시비는 관행시비와 차이가 없었으나 완효성비료 80%이상에서는 관행시비보다 증수되었다. 이상에서와 같이 질소이용율, 생육, 도복 및 수량을 고려한 벼 건답직파 조기파종 재배에 알맞은 완효성비료 전층시비량은 질소관행 시비량의 80%정도라고 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1128-1133
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• 2004

A comprehensive experimental and numerical study has been conducted to understand the influence of $CH_{3}Cl$ addition on $CH_{4}/O_{2}/N_{2}$ premixed flames under the oxygen enrichment. The laminar flame speeds of $CH_{4}/CH_{3}Cl/O_{2}/N_{2}$ premixed flames at room temperature and atmospheric pressure are experimentally measured using Bunsen nozzle flame technique, varying the amount of $CH_{3}Cl$ in the fuel, the equivalence ratio of the unburned mixture, and the level of the oxygen enrichment. The flame speeds predicted by a detailed chemical kinetic mechanism employed are found to be in excellent agreement with those deduced from experiments. As $CH_{3}Cl$ addition is increased temperature at the postflame is not almost varied but the heat release rate and $EI_{NO}$ are decreased. The function of $CH_{3}Cl$ as inhibitor on hydrocarbon flames becomes weakened as the level of the oxygen enrichment is increased from 0.21 to 0.5.

• 대한기계학회논문집B
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• 제29권2호
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• pp.255-262
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• 2005

A comprehensive experimental and numerical study has been conducted to understand the influence of $CH_{3}Cl$ addition on $CH_4/O_2/N_2$ premixed flames under the oxygen enrichment. The laminar flame speeds of $CH_4/CH_{3}Cl/O_2/N_2$ premixed flames at room temperature and atmospheric pressure are experimentally measured using Bunsen nozzle flame technique, varying the amount of $CH_{3}Cl$ in the fuel, the equivalence ratio of the unburned mixture, and the level of the oxygen enrichment. The flame speeds predicted by a detailed chemical kinetic mechanism employed are found to be in excellent agreement with those deduced from experiments. Even though the molar amount of $CH_{3}Cl$ in a methane flame is increased, temperature at the postflame is not significantly varied, but the calculated heat release rate and emission index of NO are largely decreased for the oxygen enhanced flame. The function of $CH_{3}Cl$ as inhibitor on hydrocarbon flames becomes weakened as the level of the oxygen enrichment is increased from 0.21 to 0.5.

• 약학회지
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• 제44권4호
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• pp.293-299
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• 2000

Biodegradable microspheres made from poly-lactide-co-glycolide polymers have been considered as a new delivery system for single-dose vaccine. Purified tetanus toxoid (TT) was encapsulated in poly-lactide(PLA) and poly-lactide-co-glycolide (PLGA) microparticles using a solvent evaporation method in a multiple emulsion system (water-in oil-in water). The morphology of 77-loaded microparticles was spherical and the suface of them was smooth. The particle size was in a range of 2-10. Protein loading efficiency was 68-97.8%. PLGA (85:15) microparticle showed the highest efficiency. Protein release pattern was influenced by polymer molecular weight and composition. The release rate of PLA(Mw 100,000) microsphere was higher than any other microspheres. In consequence of the hydrolysis of PLGA(50:50) microspheres, environmental pH decreased from 7.4 to 5.0. The PLA, PLGA (75:25) and PLGA (85:15) microshperes showed no significant pH change. The antigenicity or n in microshperes was assayed by indirect sandwich ELISA using equine polyclonal tetanus antitoxin for capture antibody and human polyclonal tetanus antitoxin for primary antibody. The antigenicity of TT in PLA (Mw 100,000), PLGA(50:50, Mw 100,000) and PLGA (75:25, Mw 73,300) after 30 days incubation showed 54, 40.9 and 76.7%, respectively.