• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.35-43
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• 2001

Both tensile and tear properties of short-fiber reinforced Chloroprene rubber have been studied as functions of the fiber aspect ratio and fiber content. Both properties increased when both the fiber aspect ratio and fiber content were increased. The fiber reinforced rubbers exhibited maximum values of these properties at a fiber aspect ratio of about 300. When the fiber aspect ratio exceeds 400, the mechanical properties decreased with the fiber content because of the non-uniform dispersion of fibers. The tensile modulus was compared with the prediction by the Halpin-Tsai equations for randomly oriented cases. A bonding agent was used in the fiber treating process. It was found that the ultimate tensile strength, torque, tearing energy and tensile modulus of the rubbers with treated fibers were much higher than those with untreated ones.

• KSBB Journal
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• 제5권2호
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• pp.159-165
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• 1990

Ethanol fermentation by Scccharomyces cervisiae was carried out in the cell recycle filter system with a cheap fabric filter having a pore size of 10${\mu}$m. Maximum biomass concentrations up to 85g/1 were obtained, but in practice operational concentrations were between 50 and 80g/1. Ethanol productivity was 42g/1-hr, with an ethanol concentration of 66g/1 and an ethanol yield of over 86%. Continuous operation was possible by applying periodic backflushing. The ethanol fermentation could be carried out without difficulty at a dilution rate up to 0.8h-1 In order to obtain a high cell concentration and ethanol productivity, development of filter module with the larger filtration area is required.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1191-1196
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• 2006

In this work the kinetics of volume changes of fluid spaces associated with infusion of Ringer's solution are analyzed using the body fluid space model. During infusion of Ringer's solution, the human body is assumed to be characterized by the fluid space model into which fluid is fed and from which fluid is left. Various infusion types were tested to accommodate different medical situations. Volunteers were given Ringer's solution and the changes in blood hemoglobin were detected. From the comparison with experimental data, the single- and two-fluid space models were found to represent adequately the kinetics of human volume expansion during infusion of Ringer's solution.

• 한국토양비료학회지
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• 제15권2호
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• pp.141-146
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• 1982

돈분(豚糞)을 이용(利用)하여 2회(回)에 걸친 메탄발효폐액(醱酵廃液) 상징액(上澄液)(pH:7.85, $NH_4$-N:683ppm, Ec:$8.3m{\cdot}mhos/cm$, BOD:1,000ppm내외(內外))을 지하수(地下水)로 희석(稀釋)하여 녹조류(綠藻類) 1종(種)(Scenedesmus), 좀개구리밥(Lemner minor L.) 및 Azolla 1종(種)(Azolla pinnata)을 재배(栽培)코져할 때 폐액(廃液)의 적정희석재수(適正稀釋倍数)와 희석액(稀釋液)의 교환간격(交換間隔)을 알고져 vat시험(試験)으로 실시(実施)한 결과(結果), 1. 녹조류(綠藻類) 생육(生育)에는 폐액(廃液)을 5배(倍)(접종시(接種時) $NH_4$-N:137ppm)로 희석(稀釋)하여 매(每) 8일간격(日間隔)으로 교환(交換), 좀개구리밥은 25~50배(倍)(접종시(接種時) $NH_4$-N: 7~14ppm) 희석(稀釋)하여 4일간격교환(日間隔交換), Azolla는 50배희석(倍稀釋)(접종시(接種時) $NH_4$-N:14ppm) 매(每) 4~8일(日)마다 교환시(交換時)에 생육(生育)이 제일 좋았다. 2. 녹조류(綠藻類), 좀개구리밥 및 Azolla가 생육(生育)할 시(時)에 메탄가스폐액(廃液)의 pH, Ec 및 $NH_4$-N가 감소(減少)되어 폐액(廃液)의 정화(淨化)가 촉진(促進)되었다.

• KSBB Journal
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• 제10권3호
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• pp.241-248
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• 1995

염색가공 폐수 중 난분해성 물질이 PYA를 처리 하기 위하여, 한천-acrylamide를 이용한 bead를 제 조한 후 air-lift 반응기에서 연속실험을 행하였다. 합성폐수의 PYA놓도가 $3,100mg/\ell$. 체류시간 24hr일 때 유출수의 농도는 $4500mg/\ell$ 이며, 제거효율은 85% 이상을 나타내었다. 실제 호발폐수의 경우 PYA 및 COD농도가 $3,253mg/\ell$, $4,500mg/\ell$일 때, 체류시간 24hr에서 유출수의 농도는 $840mg/\ell, 480mg/\ell$이며, 제거효 율은 81.3%와 85.2%로 각각 나타났다. bead의 지름이 lmm일 때는 내부의 미생물 성장 이 양호하였으나 bead의 지름이 2mm일 때는 기질 과 산소전달저항에 의하여 반지름의 48% 이상은 미 생물의 성장이 저해를 받았다. 고정화 반응기에서 전체 기질 제거속도 중 bead 내 고정화 cell의 제거 분율은 평균 70%로 나타났다. 현탁 반응기에서 희석율 $0.083hr^{-1}$ 이상에서는 기질 이용속도가 감소하였으나 고정화 반응기에서는 희석율 $0.125hr^{-1}$까지 거의 선형척으로 증가하였다. PYA 제거속도식에서 포화상수 $K_s=6.60(g PVA/\ell)$와 최대 비기질 이용속도 k=0.175(g PVA/g cell.hr)를 얻었다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권4호
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• pp.526-532
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• 2006

The aim of this study was to evaluate the chemical composition, in vitro DM degradability, ME and OMD of alfalfa-maize silage mixtures in comparison to pure maize and alfalfa silages, and to test the existence of associative effects of ensiling alfalfa forage with whole-crop maize using the in vitro gas production technique. Ensiling alfalfa with whole-crop maize had a significant (p<0.001) effect on chemical composition, pH, in vitro DM degradability, OMD and estimated ME values of mixtures. DM content of the resultant silages significantly increased with increasing proportion of whole-crop maize in the mixtures, whereas the pH value, crude protein (CP), acid detergent fibre (ADF) and ash contents of mixtures decreased due to the dilution effect of whole-crop maize which was low in CP, ADF and ash. The pH values of all alfalfa-maize silage mixtures were at the desired level for quality silage. Gas production of alfalfa-maize silage mixtures at all incubation times except 12 h increased with increasing proportion of whole-crop maize. When alfalfa was mixed with whole-crop maize in the ratio 40:60, ME and OMD values were significantly (p<0.001) higher than other silages. Maximum gas production ($A_{gas}$) ranged from 65.7 to 78.1 with alfalfa silage showing the lowest maximum gas production. The results obtained in this study clearly showed that maximum gas production increased with increased percentage of whole-crop maize in the silage mixtures (r = 0.940, p<0.001). It was concluded that ensiling alfalfa with whole-crop maize improved the pH, OMD and ME values. However, trials with animals are required to see how these differences in silage mixtures affect animal performance.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.718-724
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• 2006

The heterogeneous association behaviour of various concentration binary mixtures of mono alkyl ethers of ethylene glycol with ethyl alcohol were investigated by dielectric measurement in benzene solutions over the entire concentration range at 25 ${^{\circ}C}$. The values of static dielectric constant $\epsilon_0$ of the mixtures were measured at 1 MHz using a four terminal dielectric liquid test fixture and precision LCR meter. The high frequency limiting dielectric constant $\epsilon_\infty$ values were determined by measurement of refractive index $n_D$ ($\epsilon_\infty\;=\;n_D\;^2$). The measured values of $\epsilon_0$ and $\epsilon_\infty$ were used to evaluate the values of excess dielectric constant $\epsilon^E$, effective Kirkwood correlation factor $g^{eff}$ and corrective correlation factor $g_f$ of the binary polar mixtures to obtain qualitative and quantitative information about the H-bond complex formation. The non-linear behaviour of the observed $\epsilon_0$ values of the polar molecules and their mixtures in benzene solvent confirms the variation in the associated structures with change in polar mixture constituents concentration and also by dilution in non-polar solvents. Appearance of the maximum in $\epsilon^E$ values at different concentration of the polar mixtures suggest the formation of stable adduct complex, which depends on the molecular size of the mono alkyl ethers of ethylene glycol. Further, the observed $\epsilon^E$ < 0 also confirms the heterogeneous H-bond complex formation reduces the effective number of dipoles in these polar binary mixtures. In benzene solutions these polar molecules shows the maximum reduce in effective number of dipoles at 50 percent dilutions. But ethyl alcohol rich binary polar mixtures in benzene solvent show the maximum reduce in effective number of dipoles in benzene rich solutions.

• Journal of Microbiology and Biotechnology
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• 제17권7호
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• pp.1221-1225
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• 2007

A ${\beta}$-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at $22^{\circ}C$ and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (${\mu}_m$) and Monod constant ($K_s$) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of $0.02-0.10\;h^{-1}$. A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a ${\mu}_m$ of $0.15\;h^{-1}$ and $k_s$ of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content ($X_m$) for the mutant was estimated to be $1.04\;{\mu}g/mg$ dry cell weight, and the Lee constant ($k_m$), which was tentatively defined in this work, was found to be 3.0 h.

• 한국환경농학회지
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• 제42권2호
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• pp.93-103
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• 2023

Persistence and degradation patterns of acequinocyl and its metabolite, hydroxyl-acequinocyl (acequinocyl-OH) and fenpyroximate in butterburs (Petasites japonicus Max.) were investigated after pesticide application. Butterburs, one of the minor crops in South Korea, was planted in two plots (plot A for double and plot B for single application) in a greenhouse. Butterburs samples were also planted in a separate plot without pesticide treatment, as the control. A commercial pesticide containing acequinocyl and fenpyroximate was applied to the foliage of butterburs at hourly intervals after dilution. Recoveries of acequinocyl and acequinocyl-OH were 78.6-84.7% and 83.7-95.5%, respectively; the relative standard deviation of the two compounds were less than 5%. The method limit of quantification was 0.01 mg/kg. The total (Ʃ) acequinocyl residues in butterburs reduced by 96.0% at 14 days and 75.9% at 7 days, in plot A and B, respectively, after final pesticide applications. The biological half-life (DT₅₀) of Ʃ acequinocyl and fenpyroximate, calculated using the dissipation rate, was 3.0 days and 4.0 days, respectively. These data were used to set up maximum residue and safe standard levels when the pesticides are applied to control pests during butterbur cultivation. Risk assessment results showed that the maximum % acceptable daily intake was 7.74% for Ʃ acequinocyl and 0.16% for Ʃ fenpyroximate. The theoretical maximum daily intake of Ʃ acequinocyl and fenpyroximate was 26.3% and 35.8%, respectively. In conclusion, the concentrations of Ʃ acequinocyl and fenpyroximate in butterburs pose no significant health risks to Koreans.

• 대한환경공학회지
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• 제39권6호
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• pp.332-338
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• 2017

본 연구는 혼합영양생물인 Scenedesmus acuminatus의 최적배양조건을 찾기 위한 연구로서 최적 공기주입량, 아세테이트 주입량, $CO_2$ 주입에 대해 실험을 진행하였다. 공기주입량은 0.72 vvm에서 최대 비성장속도와 최대바이오매스 생산량을 얻을 수 있었으며, 0.3 M의 아세테이트를 주입하였을 때 최대 비성장속도와 최대바이오매스 생산량을 얻었다. 반연속배양에서는 추가로 $CO_2$ 주입이 배양에 미치는 영향을 파악하였다. $CO_2$ 주입 실험에서는 아세테이트로 50% 치환한 후에 최대비성장속도($0.460d^{-1}$)와 최대바이오매스 생산성($0.936gL^{-1}d^{-1}$)을 얻을 수 있었으며 이후 치환이 계속될수록 최대비성장속도와 최대바이오매스 생산성은 지속적으로 감소하였다. 공기주입 실험에서는 JM 배지로 배양할 때 가장 높은 비성장속도($0.381d^{-1}$)와 최대바이오매스 생산성($0.253gL^{-1}d^{-1}$)을 보여주었지만 이후 아세테이트를 함유한 배지로 50% 치환하였을 때 오히려 초기값보다 감소하는 것을 관찰하였다.