• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.3
• /
• pp.423-431
• /
• 2001

Animals are one of the important memberships of the food chain. The low-efficiency rule of nutrient transfer from one member to the next in the food chain determines the low efficiency of animal agriculture for human food. On the average, about 20% feed proteins and 15% feed energy can be converted into edible nutrients for humans. The rest proportion of feed nutrients is exposed to the environment. Environmental pollution, therefore, is inevitable as animal agriculture grows intensively and extensively. The over-loading of the environment by nutrients such as nitrogen, phosphorus from animal manure results in soil and water spoilage. The emission of gases like $CH_2$, $CO_2$, $SO_2$, NO, $NO_2$ by animals are one of the contributors for the acidification of the environment and global warming. The inefficient utilization of natural resources and the probable unsafety of animal products to human health are also a critical environmental issue. Improving the conversion efficiency of nutrients in the food chain is the fundamental strategy for solving environmental issues. Specifically in animal agriculture, the strategy includes the improvements of animal genotypes, nutritional and feeding management, animal health, housing systems and waste disposal programs. Animal nutrition science plays a unique and irreplaceable role in the control of nutrient input and output in either products or wastes. Several nutritional methods are proved to be effective in alleviating environmental pollution. A lot of nutritional issues, however, remain to be further researched for the science of animal nutrition to be a strong helper for sustainability of animal agriculture.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.1
• /
• pp.45-52
• /
• 2017

This paper deals with the operation strategy of reactive power in a multi-infeed HVDC (MIHVDC) system, in which several converters are connected to the same or nearby separate AC buses. The potential problems concerning a MIHVDC system when feeding a weak AC network are as follows: the need for coordination of the recovery control, the possibility of voltage instability or low quality of the area connected to the MIHVDC system, and the risk of mutual commutation failures. These problems in MIHVDC systems are similar to those in single-infeed HVDC (SIHVDC) systems, but the differences with the phenomenon of the SIHVDC system are the interactions between converters. The main reason for the potential problems of HVDC systems (MIHVDC or SIHVDC) is voltage variation; therefore, to mitigate the voltage variations, the performances of the HVDC system should be enhanced. Consequently, to mitigate the potential problems of MIHVDC systems, several solutions are suggested in this study, including installing STATCOM and installing a line arrester on the tower. The study results will be applied to a multi-infeed HVDC system in Korea.

• Journal of Veterinary Clinics
• /
• v.29 no.1
• /
• pp.63-67
• /
• 2012

Mosquitoes are the vectors of a number of viral diseases in cattle, such as Akabane disease, bovine ephemeral fever, Ainovirus infection, Chuzan virus infection, and Ibaraki disease. These diseases are transmitted from an infected animal to a non-infected host via the blood feeding of the vector. In Korea, the National Veterinary Research and Quarantine Services, Ministry for Food, Agriculture, Forestry and Fisheries is responsible for planning, implementation, laboratory investigations and reporting the results of the national surveillance program for mosquito-borne bovine diseases (MBD). The surveillance program, which was started in 1993, focused to determine the seroprevalence of each disease in cattle herds in space and time. From the epidemiological point of view, more important component of the surveillance program is to monitor infection rates in vectors for specific pathogens because this information is essential for a more precise understanding the dynamics of these diseases in a given environment and for determining risk of transmission. The aim of this study was to describe and compare methods for estimation of vector infection rates using maximum likelihood (MLE) and minimum infection rate in pooled samples. Factors affecting MLE such as number of pools, pooling size and diagnostic test performance are also discussed, assuming some hypothetical sampling scenarios for MBD.

• Animal Bioscience
• /
• v.35 no.8
• /
• pp.1109-1120
• /
• 2022

Antibiotics used to be supplemented to animal feeds as growth promoter and as an effective strategy to reduce the burden of pathogenic bacteria present in the gastro-intestinal tract. However, in-feed antibiotics also kill bacteria that may be beneficial to the animal. Secondly, unrestricted use of antibiotics enhanced the antibiotic resistance in pathogenic bacteria. To overcome above problems, scientists are taking a great deal of measures to develop alternatives of antibiotics. There is convincing evidence that probiotics could replace in-feed antibiotics in poultry production. Because they have beneficial effects on growth performance, meat quality, bone health and eggshell quality in poultry. Better immune responses, healthier intestinal microflora and morphology which help the birds to resist against disease attack were also identified with the supplementation of probiotics. Probiotics establish cross-feeding between different bacterial strains of gut ecosystem and reduce the blood cholesterol level via bile salt hydrolase activity. The action mode of probiotics was also updated according to recently published literatures, i.e antimicrobial substances generation or toxin reduction. This comprehensive review of probiotics is aimed to highlight the beneficial effects of probiotics as a potential alternative strategy to replace the antibiotics in poultry.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.3
• /
• pp.393-408
• /
• 1996

The effect of various levels of ascidian tunic extracts and carophyll pink on the growth rate, pigmentation, lipid and total cholesterol accumulation, and fatty acid compositions were studied in kuruma prawn, Penaeus japonicus. The kuruma prawn was fed the purified diets with or without ascidian tunic extract and carophyll pink at the levels of 100, 200, and 400 ppm for 8 weeks. In the experiment diet with ascidian tunic extracts or carophyll pink, the values of daily growth rate were ranged between $1.065\;to\;1.292%$, compared with control group. The content of astaxanthin in kuruma prawn was not significantly affected by the feeding levels of tunic extracts. Feeding of the tunic extracts, on the other hand, increased the kuruma prawn lipid and total cholesterol content, and pigment deposition in concentration-dependent manners without influencing the free astaxanthin concentration of prawn flesh and heads between two feeding groups(200 and 400 ppm). And it was also demonstrated that the dietary astaxanthin was deposited in kuruma prawn body tissue mainly as astaxanthin esters. The results suggest that the best feeding strategy for pigmentation in kuruma prawns is the diets with ascidian tunic extracts at the level of 4g/kg feed (200 ppm) for 8 weeks.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.7 no.3
• /
• pp.138-149
• /
• 2002

Plant cell culture provides a viable alternative over whole plant cultivation for the production of secondary metabolites. In order to successfully cultivate the plant cells at large scale, several engineering parameters such as, cell aggregation, mixing, aeration, and shear sensitivity are taken into account for selection of a suitable bioreactor. The media ingredients, their concentrations and the environmental factors are optimized for maximal synthesis of a desired metabolite. Increased productivity in a bioreactor can be achieved by selection of a proper cultivation strategy (batch, fed-batch, two-stage etc.), feeding of metabolic precursors and extraction of intracellular metabolites. Proper understanding and rigorous analysis of these parameters would pave the way towards the successful commercialization of plant cell bioprocesses.

• Proceedings of the KIPE Conference
• /
• 1996.06a
• /
• pp.103-108
• /
• 1996

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic(PV) system is connected in parallel between utility and load. The PV system provides an uninterruptable voltage to load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system. 1. Harmonic elimination Function 2. Feeding the photovoltaic energy to the utility 3. Providing the uninterruptible power source along battery to the load In case that the photovoltaic array system is on the poor power generation, the battery and capacitor of the PV system are charged by three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to load and reactive power to utility in order to maintain the unity power factor and to regulate ac load voltage.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.3
• /
• pp.381-385
• /
• 2006

The production of astaxanthin by Xanthophyllomyces dendrorhous mutant depended on the culture conditions. Therefore, a cultivation strategy, including effective chemical and light induction, for the high-level production of astaxanthin by X. dendrorhous mutant JH1 was explored. Effective chemicals such as ethanol, acetic acid, and hydrogen peroxide, which are known inducers or precursors of astaxanthin synthesis, were investigated for their increase of astaxanthin production. Each of 1.0% ethanol, 1.0% acetic acid, and 1.0% hydrogen peroxide increased the astaxanthin concentration to 49.77 mg/l, 46.33 mg/l, and 45.61 mg/l, respectively. Among these chemicals, 1.0% ethanol showed the best effect on increasing astaxanthin concentration after 48 h of cultivation. Under 1.0% ethanol feeding condition, high light intensity (2,400 lux) stimulated astaxanthin production to 59.67 mg/l, compared with that in the dark-grown cultivation.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.3
• /
• pp.334-341
• /
• 2011

This paper presents accurate solutions for nonlinear transcendental equations of the selective harmonic elimination technique used in three-phase PWM inverters feeding the induction motor by particle swarm optimization (PSO). With the proposed approach, the required switching angles are computed efficiently to eliminate low order harmonics up to the $23^{rd}$ from the inverter voltage waveform, whereas the magnitude of the fundamental component is controlled to the desired value. A set of solutions and the evaluation of the proposed method are presented. The obtained results prove that the algorithm converges to a precise solution after several iterations. The salient contribution of the paper is the application of the particle swarm algorithm to attenuate successfully any undesired loworder harmonics from the inverter output voltage. The current paper demonstrates that the PSO is a promising approach to control the operation of a three-phase voltage source inverter with a selective harmonic elimination strategy to be applied in induction motor drives.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.8 no.5
• /
• pp.303-305
• /
• 2003

Scale-up of hirudin production from Saccharomyces cerevisiae from bench-scale to pilot-scale was carried out based on constant volumetric oxygen transfer coefficient (K$\sub$L/a). Fed-batch mode of cultivation using step-wise feeding strategy of galactose was employed for the production of hirudin in a 30-L and a 300-L pilot-scale fermentor. The final hirudin concentrations were achieved 390 mg/L and 286.1 mg/L, and the volumetric productivities were 80.4% and 90.7% with the 30-L and 300-L fermentors, respectively, compared to the productivity of the 5-L bench-scale fermentor.