• 한국철도학회논문집
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• 제17권3호
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• pp.171-177
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• 2014

PWM컨버터 차량은 전압벡터제어방식에 의해 부하역률 1.0에 가까운 운전이 가능하므로 기존 저역률의 위상제어방식 차량에 비해 급전선로 전압강하 측면에서 우수한 부하특성을 나타낸다. 그러나 이 경우에도 급 전구간 내의 운전밀도가 높거나 연장급전 구간에서는 선로손실의 증가 및 전압강하 현상이 심각한 수준으로 나타날 수 있다. 본 논문은 PWM컨버터 차량의 역률을 1.0으로 고정하여 운행하는 대신 차량의 운전 조건에 따라 가변적으로 최적 제어함으로써 급전선로의 손실을 최소화 하고 전압 프로파일을 개선하는 방법을 기술하였다. 제시된 방법은 동일 급전구간 내에 운행중인 차량을 대상으로 최대 경사법에 의해 선로의 무효전력손실이 최소화되는 개별 차량의 무효전력 보상량을 결정하게 되며, 이 방법을 표본 계통에 대해 시뮬레이션 한 결과 선로손실의 감소와 함께 전압 프로파일도 상당한 수준으로 개선됨을 알 수 있었다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권10호
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• pp.1449-1453
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• 2015

The objective of the present study was to determine the effects of feeding pelletized broccoli byproducts (PBB) on milk yield and milk composition in dairy cows. In Trial 1, an in vitro gas test determined the optimal replacement level of PBB in a concentrate mixture in a mixed substrate with Chinese wild ryegrass hay (50:50, w/w) at levels of 0, 10%, 20%, 30%, or 40% (dry matter basis). When the concentrate was replaced by PBB at a level of 20%, no adverse effects were found on the gas volume or its rate constant during ruminal fermentation. In trial 2, 24 lactating cows (days in milk = $170.4{\pm}35$; milk yield = $30{\pm}3kg/d$; body weight = $580{\pm}13kg$) were divided into 12 blocks based on day in milk and milk yield and randomly allocated to two dietary treatments: a basic diet with or without PBB replacing 20% of the concentrate mixture. The feeding trial lasted for 56 days; the first week allowed for adaptation to the diet. The milk composition was analyzed once a week. No significant difference in milk yield was observed between the two groups (23.5 vs 24.2 kg). A significant increase was found in milk fat content in the PBB group (p<0.05). Inclusion of PBB did not affect milk protein, lactose, total solids or solids-not-fat (p>0.05). These results indicated that PBB could be included in dairy cattle diets at a suitable level to replace concentrate mixture without any adverse effects on dairy performance.

• 환경생물
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• 제35권2호
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• pp.152-159
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• 2017

For the effective seedling production of the hard shelled mussel, Mytilus coruscus, this study assessed the effects of the dietary value of live food, density, water temperature and salinity on growth and survival rate of the larvae. The optimal survival rate and growth rate were examined under differing conditions of water temperature, salinity, and rearing density for 30 days. The three groups were provided different feeding organisms, such as Isochrysis galbana and Teleaulax suecica. The mixtures were provided at a rate of $5{\times}10^4cell\;mL^{-1}$. The best growth was observed in the group with conditions $21^{\circ}C$ water temperature ($16.2{\pm}9.1{\mu}m$), 33 psu of salinity ($16.82{\pm}3.9{\mu}m$), $2500individual\;m^{-2}$ ($17.2{\pm}5.9{\mu}m$), and fed with $5{\times}10^4cell\;mL^{-1}$ of I. galbana and T. suecica mixture ($16.0{\pm}7.3{\mu}m$). The highest survival rate was found in the group at conditions $18^{\circ}C$ water temperature (66.4%), 33 psu of salinity (24.4%), $2500individual\;m^{-2}$ (65.8%), and fed with $5{\times}10^4cell\;mL^{-1}$ of I. galbana and T. suecica mixture (58.8%). We therefore conclude that the suitable culture conditions for the stable production of hard shelled mussel artificial seedlings was at 18 to $21^{\circ}C$ of temperature, 30 to 33 psu of salinity, 2500 to $5000individual\;m^{-2}$ of rearing density, and feeding supplement of $5{\times}10^4cell\;mL^{-1}$ of I. galbana and T. suecica mixture under semi running water system.

• 한국미생물·생명공학회지
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• 제28권2호
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• pp.105-110
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• 2000

강력한 함암작용을 나타내는 단백다당체를 생산하는 Phellinus linteus WI-001 균주를 대상으로 배양학적 특성 및 초기 배양배지의 탄소원인 glucose 농도에 따른 균사체 생산성을 조사하였다. 배양중 최적 pH와 온도는 각각 5.5와 28$^{\circ}C$인 것으로 나타났다. 특히 pH의 경우 전 배양기간에 걸쳐 5.5에서 6.5의 비교적 좁은 범위에서 변화하였다. 초기 glucose 농도를 0.5%, 1%, 2%, 3% 및 4%에서 균사체 생산량 및 세포비성장속도를 조사한 결과 최종 균사체 생산량은 glucose 농도가 증가할수록 높게 나타났으나, 세포비성장속도가 가장 빠르게 나타나는 초기 1% glucose 조건하에서 배양하다가 추가로 glucose를 간헐적 또는 지속적으로 공급하는 전략으로 생산성 향상을 시도하였다. 그 결과 회분식 배양에 비해 간헐적 공급방식에서는 28% 지속적 공급방식에서는 42%의 수율이 증가되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권8호
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• pp.1163-1170
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• 2015

Two probiotic strains, Lactobacillus johnsonii x-1d-2 and Lactobacillus mucosae x-4w-1, originally isolated from piglet feces, have been demonstrated to possess antimicrobial activities, antibiotic resistances and interleukin-6 induction ability in RAW 267.4 macrophages in our previous study. These characteristics make L. johnsonii x-1d-2 and L. mucosae x-4w-1 good candidates for application in feed probiotics. In this study, soybeal meal, molasses and sodium acetate were selected to optimize the growth medium for cultivation of L. johnsonii x-1d-2 and L. mucosae x-4w-1. These two strains were then freeze-dried and mixed into the basal diet to feed the weaned piglets. The effects of L. johnsonii x-1d-2 and L. mucosae x-4w-1 on the growth performance and fecal microflora of weaned piglets were investigated. The results showed that the bacterial numbers of L. johnsonii x-1d-2 and L. mucosae x-4w-1 reached a maximum of 8.90 and 9.30 log CFU/mL, respectively, when growing in optimal medium consisting of 5.5% (wt/vol) soybean meal, 1.0% (wt/vol) molasses and 1.0% (wt/vol) sodium acetate. The medium cost was 96% lower than the commercial de Man, Rogosa and Sharpe medium. In a further feeding study, the weaned piglets fed basal diet supplemented with freeze-dried probiotic cultures exhibited higher (p<0.05) body weight gain, feed intake, and gain/feed ratio than weaned piglets fed basal diet. Probiotic feeding also increased the numbers of lactobacilli and decreased the numbers of E. coli in the feces of weaned piglets. This study demonstrates that L. johnsonii x-1d-2 and L. mucosae x-4w-1 have high potential to be used as feed additives in the pig industry.

• Asian-Australasian Journal of Animal Sciences
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• 제22권11호
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• pp.1540-1546
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• 2009

One hundred and forty-four piglets with an average birth weight of 1,672${\pm}$13.4 g were used to evaluate different feeding strategies for piglets reared from birth on a dummy sow. A 3${\times}$2 factorial experiment compared three nursing frequencies (1, 3 or 6 h intervals) and two feeding regimes (milk only, or milk combined with access to creep feed and water). The piglets which were nursed at one hour intervals had the lightest body weights at all days, and the poorest combined milk and creep feed dry matter conversion efficiency to piglet body weight gain in the second week. Piglets which were nursed at 3 h intervals had the heaviest body weight at day 15 and 22, but those nursed at 6 h intervals achieved similar body weight by days 29 (milk withdrawal) and 36. Piglets offered creep feed were observed to wean themselves before cessation of milk availability, and the timing of this self-weaning depended on the nursing frequency. The piglets nursed at one hour intervals weaned themselves between day 22 and day 29, those nursed at 3 h intervals weaned themselves between day 15 and day 22, whilst those nursed at 6 h intervals weaned themselves between day 8 and day 15. The piglets which were nursed at 6 h intervals had the highest total dry matter intake in weeks 3 and 4 when fed with milk, creep feed and water but not when fed milk only. They consequently had the poorest dry matter conversion efficiency in the fourth week and overall when fed with milk, creep feed and water, but not when fed milk only. It is concluded that the optimal management routine under these conditions is a 3 h nursing cycle with provision of supplementary creep feed and water.

• 한국균학회지
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• 제35권1호
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• pp.37-42
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• 2007

잣버섯 균사체 배양에 적합한 생물반응기는 풍선형의 공기부양식의 생물반응기가, 수용성 다당체의 생산에도 생장이 좋았던 풍선형 공기부양식 생물반응기가 유리한 것으로 나타났다. 배지의 탄소원 농도별에 따른 수용성 세포외 다당체의 생산량은 농도 처리간 차이가 없었으나 수용성 세포내 다당체는 탄소원 농도가 낮은 즉 C/N율이 낮을수록 증가하였다. 잣버섯 균사체는 고농도의 배지 배양조건에서 생물반응기내로 배지 공급형태가 배지량 증가방법보다 배지농도 조절에 의한 연속 배양방법이 우수한 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제40권1호
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• pp.10-18
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• 2015

Purpose: The study was conducted to investigate the proper working conditions like the mesh size of the concave and the chaffer angle of the oscillating sieve, and the fan speed of the head-feeding rice combine for foxtail millet harvesting. Methods: The study aimed to determine the harvesting conditions for the rice combine harvester at a 0.5 m/s working speed and at $40^{\circ}$ and $55^{\circ}$ sieve chaffer angles. The harvesting loss of the foxtail millet based on the speed of the fan and the oscillating speed of the sieve was measured at three levels of fan speed and oscillating sieve speed. Results: The threshing rates of different foxtail millet varieties were 64.1~83.5% at a mesh size of 7 mm of the concave. In experimental foxtail millet harvesting, the optimal operating condition of the rice combine harvester included a $40^{\circ}$ sieve chaffer angle and a 4.8 Hz oscillating sieve (cleaning shoe) frequency. The grain loss was found to be lower at a $40^{\circ}$ than at a $55^{\circ}$ sieve chaffer angle. In field harvesting using the combine harvester, the lowest harvesting grain loss rate of the foxtail millet varieties ranged between 0.2~0.5% at a 7 mm mesh concave, $40^{\circ}$ chaffer angle, 4.8 Hz sieve frequency, and a 20 m/s fan speed at an engine speed of 2,000 revolutions per minute (RPM). Conclusions: Findings showed that foxtail millet could be harvested using the combine harvester.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.296-302
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• 2018

Purpose: The aim of this study was to determine appropriate threshing and selection conditions for sorghum harvesting using a rice combine-harvester. Methods: Sorghum harvesting performance was tested using an actual rice combine. Through this test, the grain loss rate and the composition of crops according to the engine and fan speeds of the combine were investigated. Furthermore, the optimal threshing and selection conditions were determined by carrying out a harvest test based on the opening size factor of the concave in a test field. Results: The grain loss rate for the sorghum using a concave ($18{\times}18mm$) of the rice combine was the lowest at 0.1% at a chaffer angle of $40^{\circ}$, engine speed of 2000 rpm, and fan speed of 20 m/s, but the sorting sieve clogged frequently. Furthermore, as the engine speed and fan speed increased, the grain loss rate also increased. The sorghum harvesting test results of the combine according to the concave opening size showed that the grain loss rate was 0.5% at a driving speed of 0.5 m/s, with a concave opening diameter of 13 mm, a chaffer angle of $40^{\circ}$, a concave sieve oscillation frequency of 4.8 Hz, a fan speed of 20 m/s, and an engine speed of 2000 rpm. Conclusions: Findings showed that sorghum could be harvested using a head feeding rice combine.

• Asian-Australasian Journal of Animal Sciences
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• 제32권10호
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• pp.1511-1520
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• 2019

Objective: The present study was conducted to select a plant oil without inhibitory effects on rumen fermentation and microbes, and to determine the optimal supplementation level of the selected oil in a series of in vitro studies for dietary application. Then, the selected oil was evaluated in a feeding study using Thai crossbred beef cattle by monitoring growth, carcass, blood and rumen characteristics. Methods: Rumen fluid was incubated with substrates containing one of three different types of plant oil (coconut oil, palm oil, and soybean oil) widely available in Thailand. The effects of each oil on rumen fermentation and microbes were monitored and the oil without a negative influence on rumen parameters was selected. Then, the dose-response of rumen parameters to various levels of the selected palm oil was monitored to determine a suitable supplementation level. Finally, an 8-month feeding experiment with the diet supplemented with palm oil was carried out using 12 Thai crossbred beef cattle to monitor growth, carcass, rumen and blood profiles. Results: Batch culture studies revealed that coconut and soybean oils inhibited the most potent rumen cellulolytic bacterium Fibrobacter succinogenes, while palm oil had no such negative effect on this and on rumen fermentation products at 5% or higher supplementation level. Cattle fed the diet supplemented with 2.5% palm oil showed improved feed conversion ratio (FCR) without any adverse effects on rumen fermentation. Palm oil-supplemented diet increased blood cholesterol levels, suggesting a higher energy status of the experimental cattle. Conclusion: Palm oil had no negative effects on rumen fermentation and microbes when supplemented at levels up to 5% in vitro. Thai crossbred cattle fed the palm oil-supplemented diet showed improved FCR without apparent changes of rumen and carcass characteristics, but with elevated blood cholesterol levels. Therefore, palm oil can be used as a beneficial energy source.