• Asian-Australasian Journal of Animal Sciences
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• 제15권10호
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• pp.1458-1468
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• 2002

There is increasing interest in exploiting natural products as feed additives to solve problems in animal nutrition and livestock production. Essential oils and saponins are two types of plant secondary compounds that hold promise as natural feed additives for ruminants. This paper describes recent advances in research into these additives. The research has generally concentrated on protein metabolism. Dietary essential oils caused rates of NH$_3$ production from amino acids in ruminal fluid taken from sheep and cattle receiving the oils to decrease, yet proteinase and peptidase activities were unchanged. Hyper-ammonia-producing (HAP) bacteria were the most sensitive of ruminal bacteria to essential oils in pure culture. Essential oils also slowed colonisation and digestion of some feedstuffs. Ruminobacter amylophilus may be a key organism in mediating these effects. Saponin-containing plants and their extracts appear to be useful as a means of suppressing the bacteriolytic activity of rumen ciliate protozoa and thereby enhancing total microbial protein flow from the rumen. The effects of some saponins seems to be transient, which may stem from the hydrolysis of saponins to their corresponding sapogenin aglycones, which are much less toxic to protozoa. Saponins also have selective antibacterial effects which may prove useful in, for example, controlling starch digestion. These studies illustrate that plant secondary compounds, of which essential oils and saponins comprise a small proportion, have great potential as 'natural' manipulators of rumen fermentation, to the potential benefit of the farmer and the environment.

• Nuclear Engineering and Technology
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• 제31권4호
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• pp.375-384
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• 1999

The credibility of CHECWORKS FAC model analysis was evaluated for plant application in a model plant chosen for demonstration. The operation condition at each pipe component was defined before the wear rate analysis by plant data base, water chemistry analysis, and network flow analysis. The predicted wear was compared with the measured wear for 57 sample components selected from 43 susceptible line groups analysed. The inspected 57 locations represent components of highest predicted wear in each line group. Both absolute value and relative ranking comparisons indicated reasonable correlations between the predicted and the measured values. Four components showed much higher measured wear rates than the predicted ones in the feed water train from main feed water pump discharge to steam generator, probably due to high hydrazine concentration operation the effect of which had not been incorporated into the CHECWORKS model. The measured wear was higher than the predicted one consistently for components with least susceptibility to FAC. It is believed that the conservatism maintained during UT data analysis dominated the measurement accuracy. A great deal of enhancement is anticipated over the current plant pipe management program when a comprehensive plant pipe management program is implemented based on the model analysis.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1151-1157
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• 2003

The surfactant Tween 80 was evaluated for its ability to influence cumulative gas production, cellulose digestion, and enzyme activities by mixed ruminal microorganisms grown on barley grain or Orchardgrass hay. The addition of Tween 80 at a level of 0.10% significantly (p<0.05) decreased the cumulative gas production rate from both barley grain or Orchardgrass hay substrates. However, 0.05% Tween 80 did not affect gas production rates compared to the control treatment. The addition of 0.05% Tween 80 to cultures growing on barley grain resulted in a significant increase in cellulase (90.01%), xylanase (90.73%) and amylase (487.25%) activities after 30 h incubation. Cultures utilizing Orchardgrass hay had a significant increase in cellulase (124.43%), xylanase (108.86%) and amylase (271.22%) activities after 72 h incubation. These increases in activities were also observed with cultures supplemented with 0.10% Tween 80 throughout all the incubation times tested. These results indicated that the addition of 0.05% Tween 80 could greatly stimulate the release of some of key enzymes without decreasing cell growth rate in contrast to trends reported with aerobic microorganism. Our data indicates potential uses of the surfactant Tween 80 as a feed additive for ruminant animals.

• 대한기계학회논문집A
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• 제30권12호
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• pp.1634-1641
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• 2006

High-precision centerless grinding machines are emerging as a means of finishing the outer diameter grinding process required for ferrules, which are widely used as fiber optic connectors. In this study, a sensitivity analysis for structural and thermal characteristics was carried out using a virtual prototype of a centerless grinding machine to realize systematic design technology and performance improvements required to manufacture ferrules. The prototype consisted of a concrete-filled bed, hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW table feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The results of the structural sensitivity analysis illustrated that the vertical stiffness of hydrostatic guideway for the RW table feed system greatly influenced the horizontal loop stiffness, and the results of the thermal sensitivity analysis illustrated that the heat generation rates at hydrostatic bearings and belt pulley greatly influenced the temperature rise of hydrostatic bearings and the deviation of thermal displacement between GW and RW.

• Asian-Australasian Journal of Animal Sciences
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• 제5권2호
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• pp.369-374
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• 1992

In order to determine the effect of dietary cellulose levels on chick performance, 1-week-old White Leghorn male chicks were fed semi-purified diets containing either 5%, 10%, 15% or 20% cellulose for 3 weeks. All diets were iso-nitrogenous and iso-caloric. Feed intake and body weight were increased as the cellulose level was increased. Feed conversion was lower in the 5% cellulose diet than in the other diets. Compared to the case of 10% to 20% cellulose diets, relative length (per 100 g body weight) of esophagus, duodenum, small intestine and cecum was longer, and relative weight of esophagus, duodenum and crop was also heavier in the chicks fed the 5% cellulose diet. The other internal organs were not affected by the cellulose level. The retention rates of dry matter and nitrogen were lower in the 5% cellulose group than in the other groups. Concentration of carcass phospholipids was higher in the 5% cellulose group, and that of carcass cholesterol was increased as the cellulose level increased. In conclusion, the dietary cellulose level should be more than 5% to give an adequate chick performance, and no ill effect was found even at 20% level.

• 한국재료학회지
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• 제27권2호
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• pp.119-126
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• 2017

WC-CrC-Ni coatings were prepared by nine processes of the Taguchi program with three levels for the four spray parameters: spray distance, flow rates of hydrogen and oxygen, and powder feed rate. The optimal coating process (OCP) was oxygen flow rate of 38 FMR, hydrogen flow rate of 53 FMR, powder feed rate of 25 g/min, and spray distance of 7 inches. Hardness of 1150 Hv and porosity of 1.2 %, were obtained by OCP; these are better results compared with the highest 1033 Hv and the lowest 1.5 % porosity obtained by nine processes of the Taguchi program. Friction coefficient of the WC-CrC-Ni coating decreased from $0.36{\pm}0.07$ at $25^{\circ}C$ to $0.23{\pm}0.07$ at $450^{\circ}C$. These values were smaller than those of the EHC (electrolytic hard chrome) plating at both temperatures due to lubrication from the oxide debris. The wear trace and wear depth of the coating are smaller than those of the EHC at both temperatures. Pitting was not found in the WC-CrC-Ni coating sample, while it did appear in the EHC sample.

• 한국기계가공학회지
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• 제10권2호
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• pp.135-141
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• 2011

In this study, the variation of the cutting forces generated in the machining process were evaluated experimentally. A material of $Al_{2}O_{3}$ ceramic and a tool of the dynamometer were used for the measurements of the cutting forces. With the constant rates of the feed and the tool rotation, the cutting forces were measured along three axial directions(X, Y, Z axis) for the various values of the hollow ratio. It was found that the cutting force be increasing linearly along the direction of Z axis, but along X, Y axis be not varied. Also from the viewpoint of the precesses of the hole drilling, the cutting force was found to be increasing sharply at the beginning process, but from the eighth process be increasing smoothly. As conclusions, the cutting force generated by machining for the material of $Al_{2}O_{3}$ ceramic are influenced more significantly by the feed rate and the hollow ratio than by the tool rotational speed.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.908-912
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• 2008

To achieve a higher succinic acid productivity and evaluate the industrial applicability, this study used Mannheimia succiniciproducens LPK7 (knock-out: ldhA, pflB, pta-ackA), which was recently designed to enhance the productivity of succinic acid and reduce by-product secretion. Anaerobic continuous fermentation of Mannheimia succiniciproducens LPK7 was carried out at different glucose feed concentrations and dilution rates. After extensive fermentation experiments, a succinic acid yield and productivity of 0.38 mol/mol and 1.77 g/l/h, respectively, were achieved with a glucose feed concentration of 18.0 g/l and $0.2\;h^{-1}$ dilution rate. A similar amount of succinic acid production was also produced in batch culture experiments. Therefore, these optimal conditions can be industrially applied for the continuous production of succinic acid. To examine the quantitative balance of the metabolism, a flux distribution analysis was also performed using the metabolic network model of glycolysis and the pentose phosphate pathway.

• Advances in aircraft and spacecraft science
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• 제3권1호
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• pp.29-43
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• 2016

Composite materials are rapidly gaining popularity as an alternative to metals for structural and load bearing applications in the aerospace, automotive, alternate energy and consumer industries. With the advent of thermoplastic composites and advances in recycling technologies, fully recyclable composites are gaining ground over traditional thermoset composites. Stamp forming as an alternative processing technique for sheet products has proven to be effective in allowing the fast manufacturing rates required for mass production of components. This study investigates the feasibility of using the stamp forming technique for the processing of thermoplastic, recyclable composite materials. The material system used in this study is a self-reinforced polypropylene composite material (Curv$^{(R)}$). The investigation includes a detailed experimental study based on strain measurements using a non-contact optical measurement system in conjunction with stamping equipment to record and measure the formability of the thermoplastic composites in real time. A Design of Experiments (DOE) methodology was adopted to elucidate the effect of process parameters that included blank holder force, pre heat temperature and feed rate on stamp forming. DOE analyses indicate that feed rate had negligible influence on the strain evolution during stamp forming and blank holder force and preheat temperature had significant effect on strain evolution during forming.

• 한국유기농업학회지
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• 제28권4호
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• pp.615-626
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• 2020

하계사료작물로 케나프를 재배할 시에 유기 및 화학비료의 질소공급원과 수확시기를 달리하였을 때 케나프의 생산성과 양질의 조사료를 얻기 위해 적정 질소시용수준과 수확시기를 구명하고자 실시되었다. 질소공급원에 따른 케나프의 건물수량은 화학비료 처리 구가 다소 높았지만, 유기질비료를 ha 당 200~250 kg의 수준에서는 화학비료 처리 구와 유의한 차이가 인정되지 않았고 사료가치 특히 조단백질과 TDN 함량은 오히려 유기질비료 처리 구에서 유의하게 높게 나타나(p<0.05), 반추동물에게 양질의 조사료 공급원으로 이용하고자 케나프가 재배된다면 유기질비료가 화학비료를 대체할 수 있음을 시사하였다. 한편 수확시기에 따른 건물수량은 100일째가 다른 수확시기보다 유의하게 높았지만 100~110일 수확시기가 수량구성요인 중 잎의 비율이 줄기보다도 높았고 사료가치 중 조단백질과 TDN 함량이 다른 수확시기보다 높게 나타났으며 ADF와 NDF 함량은 크게 감소하였다(p<0.05). 본 연구의 결과 특히 건물수량과 사료가치를 비교해 볼 때 적절한 질소공급원으로 유기질비료를 시용 시에는 ha당 200~250 kg 정도가 적절하고 수확시기는 100~110일이 적합하다고 사료된다.