• 제목/요약/키워드: Pulse-feeding

검색결과 50건 처리시간 0.017초

Fed-Batch Sorbose Fermentation Using Pulse and Multiple Feeding Strategies for Productivity Improvement

  • Giridhar, R.;Srivastava, A.K.
    • Biotechnology and Bioprocess Engineering:BBE
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    • 제5권5호
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    • pp.340-344
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    • 2000
  • Microbial oxidation of D-sorbitol to L-sorbose by Acetobacter suboxydans is of commercial importance since it is the only biochemical process in vitamin C synthesis. The main bottleneck in the batch oxidation of sorbitol to sorbose is that the process is severely inhibited by sorbitol. Suitable fed-batch fermentation designs can eliminate the inherent substrate inhibition and improve sorbose productivity. Fed-batch sorbose fermentations were conducted by using two nutrient feeding strategies. For fed-batch fermentation with pulse feeding, highly concentrated sorbitor (600g/L) along with other nutrients were fed intermittently in four pulses of 0.5 liter in response to the increased DO signal. The fed-batch fermentation was over in 24h with a sorbose productivity of 13.40g/L/h and a final sorbose concentration of 320.48g/L. On the other hand, in fed-batch fermentation with multiple feeds, two pulse feeds of 0.5 liter nutrient medium containing 600g/L sorbitol was followed by the addition of 1.5 liter nutrient medium containing 600g/L sorbitol at a constant feed rate of 0.36L/h till the full working capacity of the reactor. The fermentation was completed in 24h with an enhanced sorbose productivity of 15.09g/L/h and a sorbose concentration of 332.60g/L. The sorbose concentration and productivity obtained by multiple feeding of nutrients was found to be higher than that obtained by pulse feeding and was therefore a better strategy for fed-batch sorbose fermentation.

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Reduced Rating T-Connected Autotransformer Based Thirty-Pulse AC-DC Converter for Vector Controlled Induction Motor Drives

  • Singh Bhim;Bhuvaneswari G.;Garg Vipin
    • Journal of Power Electronics
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    • 제6권3호
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    • pp.214-225
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    • 2006
  • The design and performance analysis of a reduced rating autotransformer based thirty-pulse AC-DC converter is carried out for feeding a vector controlled induction motor drive (VCIMD). The configuration of the proposed autotransformer consists of only two single phase transformers, with their windings connected in a T-shape, resulting in simplicity in design, manufacturing and in a reduction in magnetics rating. The design procedure of the autotransformer along with the newly designed interphase transformer is presented. The proposed configuration has flexibility in varying the transformer output voltage ratios as required. The design of the autotransformer can be modified for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed thirty-pulse AC-DC converter is capable of suppressing less than $29^{th}$ harmonics in the supply current. The power factor is also improved to near unity in the wide operating range of the drive. A comparison of different power quality indices at AC mains and DC bus is demonstrated in a conventional 6-pulse AC-DC converter and the proposed AC-DC converter feeding a VCIMD. A laboratory prototype of the proposed autotransformer based 30-pulse AC-DC converter was developed with test results validating the proposed design and system.

연속배양에서 단일항체 생산성 향상을 위한 무혈청 배지의 단계적 유입 (Pulse-Feeding of Serum Free Media for Enhancing Monoclonal Antibody Production under Perfusion Operation)

  • 강재구;박형환;이현용
    • 한국미생물·생명공학회지
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    • 제18권1호
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    • pp.61-65
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    • 1990
  • Murine hybridoma 세포배양시 lectin 계통의 생산 증진제가 무혈청 배지의 단계적 유입에 의해 약 40mg/l의 단일항체를 생산함으로서 단일항체의 생산성을 증가시킬 수 있음이 확인됐으며, 또한 이 배양공법으로 무혈청 배지에서 연속배양이 불가능한 세포의 배양이 가능했다. 이같은 무혈청 배지의 단계적 유입공법으로 약 28 x $10^{-10}$mg/cells/h의 속도로 단일항체가 생산된 것에 비해, 10 혈청이 포함된 배지로는 연속 배양시 11.1 x $10^{-10}$mg/cells/h 의 속도로 생산됐으며 회분배양의 경우는 4.0 x $10^{-11}$mg/cells/h의 속도로 생산됐다.

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Pulse Multiplication in Autotransformer Based AC-DC Converters using a Zigzag Connection

  • Singh, Bhim;Gairola, Sanjay
    • Journal of Power Electronics
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    • 제7권3호
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    • pp.191-202
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    • 2007
  • This paper deals with pulse multiplication in zigzag connected autotransformer based 12-pulse AC-DC converters feeding vector controlled induction motor drives (VCIMD) for improving the power quality at the point of common coupling (PCC) without using a Zero-Sequence-Blocking-Transformer (ZSBT). The proposed 24-pulse AC-DC converter is based on the principle of DC ripple re-injection technique for pulse multiplication and harmonic mitigation. The design of the autotransformer is carried out for the proposed AC-DC converter and the effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed AC-DC converter. Test results from a laboratory developed prototype, along with simulated results, are presented to validate the design and model of the proposed 24-pulse AC-DC converter.

식사가 정상인의 맥에 미치는 영향 분석 (Effect of Taking Meal on Pulse Diagnosis in Healthy Subjects)

  • 이유정;이전;이혜정;최은지;김종열
    • 동의생리병리학회지
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    • 제21권6호
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    • pp.1670-1675
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    • 2007
  • The pulse diagnosis studies reported to date has mainly been performed to clinically reveal the pulse wave characteristics according to the specific diseases, whereas no attempts have been made to study the effects on the pulse wave characteristics of the daily activities such as taking meals, exercise, and sleep, etc. This work reports the effect of feeding stimulus on the healthy subjects on the pulse wave pattern which has quantitatively been analyzed using the objective model for the pulse diagnosis in oriental medicine. The pulse waves right before/after the meal and 30 minutes after the meal were measured using the pulse analyzing equipment (3D-Mac, Daeyo Medi, Korea) and at the same time oriental medicine doctors' diagnoses were given. The pulse parameters obtained from the equipment and clinical records on the subjects were statistically processed and the variables showing statistically significant differences were analyzed. The results indicate that the pulse pressure, the pulse rate, and the respiratory rate increase while the blood pressure decreases after the meal. For the floating/sinking and the deficient/excess coefficients characterizing the pulse states described in the oriental medicine, the floating/sinking coefficients were observed to decrease whereas the deficiency/excess coefficients increase after the meal. The results indicates that besides the standard bio-indicators like blood pressure and respiratory rate, etc., the pulse wave characterization in terms of the pulse classifications in the oriental medicine using the floating/sinking, deficient/excess pulse states provide an important piece of biomedical information.

Feeding specificity and photosynthetic activity of Korean sacoglossan mollusks

  • Klochkova, Tatyana A.;Han, Jong-Won;Kim, Ju-Hyoung;Kim, Kwang-Young;Kim, Gwang-Hoon
    • ALGAE
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    • 제25권4호
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    • pp.217-227
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    • 2010
  • During feeding on algal cytoplasm, some sacoglossans are known to keep the chloroplasts photosynthetically active for days to months in their digestive cells. Korean sacoglossan mollusks containing functional chloroplasts were screened using an in vivo chlorophyll fluorescence measuring system (pulse amplitude modulation, PAM). We collected six sacoglossans feeding on siphonous and siphonocladous green algae (Elysia atroviridis, E. nigrocapitata, E. ornata, Ercolania boodleae, Placida dendritica, Stiliger sp.) and one feeding on ceramiaceaen algae (Stiliger berghi) and performed feeding experiments using 37 algal species. Three species of Elysia showed strong photosynthetic activity for months. However, P. dendritica maintained functional chloroplasts only for several hours after feeding. E. boodleae, S. berghi, and Stiliger sp. showed no photosynthetic activity in any circumstances. Among all species, E. nigrocapitata was capable to tolerate the longest period of starvation for over 4 months. Four 'solar powered' sacoglossans bonded avidly to their specific algal food. Each species attached to and consumed only one algal species when several algae were given together. While they occasionally consumed other algae after prolonged starvation, they always reverted to their specific algae when available.

구연산을 이용한 스테인레스 스틸의 미세 전해가공 (Micro Electrochemical Machining of Stainless Steel Using Citric Acid)

  • 류시형
    • 한국정밀공학회지
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    • 제25권3호
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    • pp.134-140
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    • 2008
  • Micro electrochemical machining (ECM) is conducted on stainless steel 304 using non-toxic electrolyte of citric acid. Electrochemical dissolution region is minimized by applying a few hundred second duration pulses between the tungsten SPM tip and the work material. ECM characteristics according to citric acid concentration, feeding velocity and electric conditions such as pulse amplitude, pulse frequency, and offset voltage are investigated through a series of experiments. Micro holes of $60{\mu}m$ in diameter with the depth of $50{\mu}m$ and $90{\mu}m$ in diameter with the depth of $100{\mu}m$ are perforated. Square and circular micro cavities are also manufactured by electrochemical milling. This research can contribute to the development of safe and environmentally friendly micro ECM process.

고온 초전도 마이크로스트립 패치 안테나; 비방사면 급전방식을 이용한 초전도 안테나 특성 (High Tc Superconducting Microstrip Patch antenna ; Characterization of Superconducting Antenna using Non-Radiating Edge Feeding Technique)

  • 정동철;박성진;황종선;박종광;한병성
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제49권7호
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    • pp.375-381
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    • 2000
  • In this paper, we described the characterization of High-Tc Superconducting(HTS) microstrip antenna using non-radiating edge feeding technique and reported the microwave properties of HTS antennas with temperature. To do this, we prepared the $YBa_2Cu_3O_{7-x}$ superconducting thin film on MgO substrate using pulse-laser deposition techniques. The HTS microstrip antenna using non-radiating feeding technique was fabricated using chemical wet-etching. Then it was compared with identical antenna patterned with evaporated gold. The diverse measured results have been reported in terms of the input impedance, resonant frequency and return loss. In additional, at around the critical temperature, the effect of kinetic inductance which affect the resonant characteristic of the HTS microstrip antenna was reported.

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철도 전력공급시스템에서의 고조파전류 확대현상에 관한 연구 (A Study on the Propagation of Harmonic Current in the Traction Power Supply System)

  • 오광해;창상훈;한문섭;이장무;신한순
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 하계학술대회 논문집 C
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    • pp.908-910
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    • 1998
  • Modern AC electric car has PWM(Pulse Width Modulation) -controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit. As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current. The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.

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철도 급전시스템에서의 고조파 해석 및 대책 연구 (A Study on the Countermeasures to Suppress Harmonics in the Traction Power Supply System)

  • 오광해;이장무;창상훈;한문섭;김길상
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 1999년도 추계학술대회 논문집
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    • pp.318-325
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    • 1999
  • Modern AC electric car has PWM(Pulse Width Modulation)-controlled converters, which give rise to higher harmonics. The current harmonics injected from AC electric car is propagated through power feeding circuit, As the feeding circuit is a distributed constant circuit composed of RLC, the capacitance of the feeding circuit and the inductance on the side of power system cause a parallel resonance and a magnification of current harmonics at a specific frequency. The magnified current harmonics usually brings about various problems. That is, the current harmonics makes interference in the adjacent lines of communications and the railway signalling system. Furthermore, in case it flows on the side of power system, not only overheating and vibration at the power capacitors but also wrong operation at the protective devices can occur. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. From these point of view, this study presents an approach to model and to analyse traction power feeding system focused on the amplification of harmonic current The proposed algorithm is applied to a standard AT(Auto-transformer)-fed test system in which electric car with PWM-controlled converters is running.

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