• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.214-216
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• 2001

인터넷에서 멀티미디어 서비스와 실시간 서비스의 요구가 증대하고 사용자가 요구하는 서비스의 품질이 높아짐에 따라 기존의 한정된 무선 자원은 부족하게 되었다. 이에 여러 가지 이동성 관리 방안들이 제시되었다. 본 논문에서는 셀룰러 IP를 기반으로 효율적인 이동성 관리를 위해 가상 대신을 이용한 이동성 관리 방안을 제안한다. 기존의 셀룰러 IP에서 구현한 Semisoft 핸드오프는 Crossover 베이스 스테이션을 통한 핸드오프 알고리즘으로 디자인 되어있다. 빠른 핸드오프를 위해 기존의 Semisoft 핸드오프 알고리즘을 확장하여 Semisoft 지연을 최소화하도륵 셀룰러 IP 프로토콜을 확장한다. 이 논문에서 Semisoft 핸드오프 알고리즘과 이를 위한 네트웍 구조를 설계한다. 이는 가상머신을 적용된 FA(Foreign Agent)인 VFA(Virtual Foreign Agent)를 통해 구현한다. 또한 VFA를 바탕으로 Semisoft 지연을 최소화하여 QoS의 보장을 해결한다.

• Journal of Animal Science and Technology
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• v.45 no.2
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• pp.241-250
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• 2003

Accurate and rapid evaluation of the nutritional quality of Korean straws is important because of the recent increase in the use of these feedstuffs in Korean. The aim of the study was to establish with relationships between ruminal fermentation of Korean straws and in vitro gas production using a pressure transducer. The pressure transducer system includes pressure censors, AD board, LED monitor, and the computer with real-time graphics. Both gas production and DM digestibility data were fitted into the exponential equation P = a + b (1-e-$1-e^{-ct}$). The initial rate of gas production was highest for rice straw, followed by barley straw and wheat straw. The gas production rate of constant (c) in gas production for rice straw, wheat straw, and barley straw were 3.8, 2.5, and 2.5 $%h^{－1}$, respectively. Total VFA concentration (mM) produced after 72h incubation was similar among three Korean straws, even though was variable during the early (12h) fermentation. Volume of gas production was related (P> 0.05: r = 0.76 to 0.83) to DM disappearance and also strongly related (p< 0.05: r = 0.91 to 0.98) to VFA concentration at all incubation times. Linear correlation showed between gas production and DM disappearance and VFA by in vitro will be matched in in vivo digestibility.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.5
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• pp.708-714
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• 1999

Fermentation of legume fodder tree leaves by rumen microorganisms was evaluated. The substrates were sun-dried, ground leaves. Gas and volatile fatty acid (VFAs) production were estimated. Using gas production as an index of fermentation at 12 h, the leaves tested ranked as follows; Chamaecytisus palmensis>Gliricidia sepium>Sebania sesban>Tephrosia bracteolate>Leucaena pallida>Vernonia amygdalina>Acacia sieberiana>Sesbania goetzei>Acacia angustissima. Using VFA production, the ranking was a follows; G. sepium>S. sesban>S. goetzei>L. pallida>C. palmensis/V. amygdalina>T. bracteolate> A. sieberiana>A. angustissima. Absolute gas or VFA production rates, were also used to rank the leaves. Extracts (70% acetone) of A. angustissima inhibited the growth of Ruminococcus albus 8, R. flavefaciens FD-1, Prevotella ruminicola D3ID and Streptococcus bovis JBI while the trowth of Selenomonas ruminantium D was depressed when 0.6 ml exracts were added. C. palmensis water extracts enhanced cellulose hydrolysis by R. flavefaciens FD-1. All extracts reduced celluloysis by R. albus 8. R. flavefaciens FD-1 hydrolyzed more (p<0.001) cellulose than R. albus 8.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.1011-1014
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• 2003

The objective of this work was to evaluate a thermotolerant yeast Issatchenkia orientalis DY252 as a microbial feed additive for ruminants. In the present study, the influence of volatile fatty acids (VFA) and temperature on oxygen uptake rate by I. orientalis DY 252 was investigated. It was evident that the oxygen uptake rate was decreased gradually as the VFA concentrations increased in a range of 30 to 120 mM. Although the oxygen uptake rate was not greatly affected by temperature in the range 37 to $43^{\circ}C$, a maximum value of $0.45mg\;O_2/g$ cell/ min was obtained at $39^{\circ}C$. With regard to the oxygen uptake rate by yeast, viability was found to be less important than the metabolic activity of yeast.

• Journal of environmental and Sanitary engineering
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• v.16 no.2
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• pp.32-37
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• 2001

The purpose of this study was to investigate the created liquid post-acid fermentation of usability of denitrification as exterior carbon sources by pH control. The time of acid fermentation of food waste, the slower loading capacity of organic matter, the faster decomposition rate, but the density of generation Volatile Fermentation Acids(VFAs), was weak and, $SBOD_{5}$ : ST-N rate and $SBOD_{5}/SCOD_{Cr}$ rate was low. Between TS and VS, VS was decreased to 4.5th day fast, and then was decreased slowly. 1.5 days after stating the experiments, $SCOD_{Cr}$, $SBOD_{5}$, STOC and $VFA_{s}$ was decreased of increased slowly, and then increased fast. And after showing the highest density, it was tended to decreased fast. At the time of $SBOD_{5}$ with the highest density, at $SBOD_{5}$ : ST-N ratio, $R_1$ was 303:1, $R_2$ was 319:1, $R_3$was the highest. After studying $SBOD_{5}$ : ST-N ratio and $SBOD_{5}/SCOD_{Cr}$ ratio, as a carbon source of biological denitrification it was profitable composition ratio.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.7
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• pp.1084-1091
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• 2007

Different levels of dietary mannanoligosaccharide (Bio-MOS, Alltech Inc.) were evaluated for their efficacy on performance and gut development of broiler chickens during a 6-week experimental period. Experimental diets contained (g MOS/kg diet) a low (0.5 g during the entire period), medium (1 g during the entire period), high (2 g during the entire period), or step down (2 g in the first week; 1 g in the second and third week; 0.5 g in the last three weeks) level of MOS. Control diets included a negative and a positive control (zinc bacitracin, ZnB, 50 ppm and 30 ppm in the first and last three weeks, respectively). MOS supplementation improved the growth performance of young birds and the effects became less when the birds got older. The growth response of birds was more obvious at the high dosage level of MOS treatment than the other MOS treatments and the growth performance of birds fed on the high MOS diet was comparable to that of birds fed on the ZnB diet. Depending on the dosage level and the age of birds, MOS seemed to reduce the size of the liver and the relative length of the small intestine but did not affect the relative weight of the other visceral organs (proventriculus, gizzard, pancreas, bursa and spleen) and that of the small intestine. A numerical increase in the small intestine digestibility of nutrients was noticed in the young birds fed on the MOS diet(s), but not in the older ones. Medium and/or high MOS treatment also increased the villus height of the small intestine of birds at different ages. Similar results were observed on the ZnB treatment. However, MOS and ZnB affected caecal VFA profile in different ways. MOS increased, or tended to increase, whereas ZnB reduced individual VFA concentrations in the caeca.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.10
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• pp.1399-1406
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• 2000

A continuous culture study was conducted to determine the impact of ruminal degradable soy protein (S-RDP) level and dilution rate (D) on growth of ruminal non-structural carbohydrate-fermenting microbes. Corn starch, urea and isolated soy protein (ISP) were used to formulate three diets with S-RDP levels of 0, 35 and 70% of total dietary CP. Two Ds were 0.03 and $0.06h^{-1}$ of the fermenter volume in a single-effluent continuous culture system. As S-RDP levels increased, digestibilities of dietary dry matter (DM), organic matter (OM) and crude protein (CP) linearly (p=0.001) decreased, whereas digestion of dietary starch linearly (p=0.001) increased. Increasing D from 0.03 to $0.06h^{-1}$ resulted in decreased digestibilities of dietary DM and OM, but had no effect on digestibilities of dietary starch (p=0.77) and CP (p=0.103). Fermenter pH, the concentration of volatile fatty acids (VFA) and daily VFA production were unaffected (p=0.159-0.517) by S-RDP levels. Molar percentages of acetate, propionate and butyrate were greatly affected by S-RDP levels (p=0.016-0.091), but unaffected by D (p=0.331-0.442). With increasing S-RDP levels and D, daily bacterial counts, daily microbial N production (DMNP) and microbial efficiency (MOEFF; grams of microbial N produced per kilogram of OM truly digested) were enhanced (p=0.001). The increased microbial efficiency with increasing S-RDP levels is probably the result of peptides or amino acids that served as a stimulus for optimal protein synthesis. The quantity of ruminal degradable protein from soy proteins required for optimum protein synthesis of non-structural carbohydrate-fermenting microbes appears to be equivalent to 9.5% of dietary fermented OM.

• Proceedings of the Korean Society of Grassland Science Conference
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• 2005.06a
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• pp.184-185
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• 2005

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.5
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• pp.672-676
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• 2003

Effect of a surfactant Tween 80 on the bacterial growth in the rumen was examined on the in vitro pure cultures of Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens, Prevotella ruminicola, Megasphaera elsidenni, Fibrobacta succinogenes, Ruminanococcus albus and Ruminococcus flavefaciens. Dry matter degradability (DMD), concentrations and compositions of volatile fatty acids (VFA), and the most probable number (MPN) of cellulolytic bacteria and total number of bacteria in the presence of Tween 80 were also examined on the in vitro rumen mixed culture either with barley grain or orchardgrass hay. The growth of S. bovis, S. ruminantium, B. fibrisolvens, P. ruminicola, M. elsidenni and F. succinogenes were significantly higher (p<0.05) at over 0.05% concentrations of Tween 80 than those of the control cultures, while was not changed with R. albus and R. flavefaciens. With rumen mixed culture the DMD of barley grain and orchardgrass hay was significantly higher (p<0.05) at a 0.2% concentration of Tween 80 than the control, being reflected in the significantly higher (p<0.05) VFA production (mmol $g^{-1}$DDM) with orchardgrass hay. The higher (p<0.05) ratio of propionate to acetate at a 0.2% concentration of Tween 80 was also observed with orchardgrass hay, showing a similar trend with barley grain. No changes in the total bacterial number and MPN of cellulolytic bacteria were observed.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.558-566
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• 2016

Biotic agents such as fumarate-reducing bacteria can be used for controlling methane (CH₄) production in the rumen. Fumarate-reducing bacteria convert fumarate to succinate by fumarate reductase, ultimately leading to the production of propionate. Fumarate-reducing bacteria in the genus Enterococcus were isolated from rumen fluid samples from slaughtered Korean native goats. The enterococci were identified as Enterococcus faecalis SROD5 and E. faecium SROD by phylogenetic analyses of 16S rRNA gene sequences. The fumarate reductase activities of the SROD5 and SROD strains were 42.13 and 37.05 mM NADH oxidized/min/mg of cellular nitrogen (N), respectively. Supplementation of rumen fermentation in vitro with the SROD5 and SROD strains produced significantly higher propionate, butyrate, and total volatile fatty acid (VFA) concentrations than controls at 12 h; VFA concentrations tended to increase after 24 h of incubation. The generated CH₄ concentration was significantly lower in the SROD5 and SROD treatment groups after 24 h of incubation. These findings indicate that E. faecium SROD has potential as a direct-fed microbial additive for increasing total VFAs while decreasing CH₄ production in rumen fermentation in vitro.