• Title, Summary, Keyword: PPF

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Implementation of PPF Controller Using Analog Circuit and Microprocessor (아날로그 회로와 마이크로 프로세서를 이용한 PPF 제어기의 구현)

  • Heo, Seok;Kim, Ki-Young;Kwak, Moon-Kyu
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.6
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    • pp.455-462
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    • 2004
  • This paper is concerned with the implementation of the active vibration suppression controller using analog circuit and microprocessor. The target active vibration controller is the positive position feedback(PPF) controller since it provides a simple algorithm suitable for both analog circuit and digital controllers. In this study, the analog PPF controller is realized using an operational amplifier and the digital PPF controller is realized using a low-cost micro-controller. The circuit diagrams are explained in detail. We then discuss the advantages and disadvantages of both methods from the view of practical implementation. Experimental results show that both implementation methods can be effectively used for the active vibration control but need to be chosen based on the mission objective.

Effects of Microperforated Film Packaging on the Improvements of Quality and Shelf-Life of Prok Bellies during Cold Storage (미세천공필름이 삼겹살의 냉장저장 중 품질 및 저장수명 향상에 미치는 영향)

  • 이근택;윤찬석
    • Food Science of Animal Resources
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    • v.21 no.3
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    • pp.227-234
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    • 2001
  • This study was conducted to determine the effects of microperforated film on the quality and shelf-life improvements of pork bellies during cold storage. Samples were stored for 14 days at 0$\pm$1$^{\circ}C$ and 55$\pm$10% r.h.. The packaging treatments were the unpackaged sample as control, the wrapped sampled with microperforated polypropylene film(MPF) and unperforated PP film(PPF), respectively. After 10 days, the counts of all kinds of microorganisms investigated tended to be the lowest in the control samples, and followed by MPF and PPF. The 'a' value for PPF was significantly lower than the values for control and MPF at 14 day. The 'L' values for MPF measured after 10 days were significantly lower than those of PPF and higher than those for control. After 4 days of storage, the 'b' values for PPF showed significantly lower than those of MPF. As storage time elapsed, percent weight loss was the highest in the control samples followed by those from MPF and PPF. Sensory analyses showed that MPF samples tended to be evaluated higher in all parameters than the control and PPF samples after 7 days. It is concluded that microperforated film wrapping can be used efficiently for maintaining the quality of fresh pork bellies during cold storage and retail display.

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Relationship between Total Solar Radiation and PPF, and Transmittance in Greenhouse at Different Weather Conditions (기상조건에 따른 온실의 전천일사량 및 광합성유효광량자속의 상관관계 및 투과율)

  • 이현우;이석건;이상호
    • Protected Horticulture and Plant Factory
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    • v.11 no.2
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    • pp.56-60
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    • 2002
  • Since the transmittance of solar radiation directly affected by the structural frames of greenhouse can be changed according to the ratio of diffuse to direct radiations, it is necessary to investigate the transmittance of greenhouse at the different weather conditions. We can easily get the data of total solar radiation from the Meteorological Administration, but we have to personally measure the photosynthetic photon flux (PPF). If the relationship between total solar radiation and PPF is established, the PPF can be simply acquired from the relationship. Sol it is required to develop the equation to calculate PPF depending on weather condition. This study was conducted to determine the transmittance of PPF at canopy level in glasshouse and the correlation between total solar radiation and PPF at clear and cloudy days. The variation phase of greenhouse transmittance at clear day was very different from that at cloudy day. It was concluded that the proper transmittance, depending on the weather condition, should be adopted to calculate the accurate total solar radiation and PPF in greenhouse. The transmittance of solar radiation was the same as that of PPF in greenhouse. It was confirmed that the ratio of PPF to total radiation increased as the amount of cloud increased. The correlation between the hourly total solar radiation and PPF was derived.

Growth of Potato Plug Seedlings as Affected by Photosynthetic Photon Flux in a Closed Transplants Production System (폐쇄형 묘생산 시스템에서 감자 플러그묘의 생장에 미치는 광합성유효광양자속의 영향)

  • Kim, Y.H.;Kim, H.J.;Lee, J.W.;Kim, J.M.
    • Journal of Biosystems Engineering
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    • v.33 no.2
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    • pp.106-114
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    • 2008
  • This study was performed to analyze the distribution of air current speed, $CO_2$ concentration, and photosynthetic photon flux (PPF) in a closed transplants production system (CTPS) for producing quality transplants. And the effect of PPF on the growth of potato (Solanum tuberosum L. cv. Dejima) plug seedlings was analyzed. Uniformity of the air current speed in CTPS was improved by installing perforated floors in duct for air circulating and by adjusting of air flow rate of the fan connected to air conditioning unit used in this study, Measured $CO_2$ concentrations were measured $409{\pm}13$, $950{\pm}25$, and $1,550{\pm}35\;{\mu}mol{\cdot}mol^{-1}$ for setting values of 400, 950, and $1,550\;{\mu}mol{\cdot}mol^{-1}$, respectively. Uniformity of PPF by adding each one the single fluorescent lamp of 20 W at both ends of the single fluorescent lamps of 40 W was highly improved. While the average PPF measured under the twin fluorescent lamps of 55 W installed at regular intervals of 10 cm was decreased by increasing the vertical distance from the lighting sources, the ratio of average PPF measured at both ends to PPF measured in the center was 74-79%. Five levels ($100{\pm}9$, $150{\pm}14$, $200{\pm}17$, $250{\pm}24$ and $300{\pm}31{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) of PPF were provided to investigate the effect of PPF on plant height, fresh weight and dry weight of potato plug seedlings produced in CTPS. Plant height was decreased by increasing PPF. Maximum fresh weight and dry weight were shown under PPF of $250{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. Thus PPF of $250\;{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was enough to produce quality potato transplants under air temperature, photoperiod, and relative humidity of $20^{\circ}C$, 16/8 h, and 70%, respectively. It was concluded that quality indices such as plant height, fresh weight and dry weight could be improved by illuminating of adequate PPF from artificial lighting sources.

The Relationship between Solar Total Radiation and Solar PPF and Transmission in Greenhouse (온실의 전천일사량 및 광합성광량자속의 상관관계 및 투과율)

  • Lee, Hyun-Woo;Lee, Suk-Gun;Lee, Jong-Won
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.261-266
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    • 2001
  • It was needed to know the amount of PPF to design greenhouse and predict the growth of crops in greenhouse. Experiments have been conducted to determine the transmission of PPF at canopy level along sky clearness condition in greenhouse, the correlation between the hourly PPF and total solar radiation. Additional experiments are needed to confirm these experimental results.

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Real-Time Tuning of the Active Vibration Controller by the Genetic Algorithm (유전자 알고리즘을 이용한 능동진동제어기의 실시간 조정)

  • 신태식
    • Journal of KSNVE
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    • v.10 no.6
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    • pp.1083-1093
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    • 2000
  • This paper is concerned with the real-time automatic tuning of the positive position feedback controller for smart structures by the genetic algorithms. The genetic algorithms haute proven its effectiveness in searching optimal design parameters without falling into local minimums thus rendering globally optimal solutions. The advantage of the positive position feedback controller is that if it is tuned properly it can enhance the damping value of a target mode without affecting other modes. In this paper, we develop for the first time a real-time algorithm for determining a tuning frequency of the PPF controller based on the genetic algorithms. To this end, the digital PPF control law is downloaded to the DSP chip and a main program, which runs the genetic algorithms in real time, updates the parameter of the controller in real time. Hence, any kind of control including the positive position feedback controller can be used in adaptive fashion in real time. Experimental results show that the real-time tuning of the positive position feedback controller can be achieved successfully. so that vibrations are suppressed satisfactorily.

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Characteristics of PPF Transmittance and Heat Flow by Double Covering Methods of Plastic Film in Tomato Greenhouse (토마토재배용 플라스틱온실의 이중피복방법에 따른 광합성유효광량자속 투과 및 열관류 특성)

  • Lee, H.W.;Sim, S.Y.;Kim, Y.S.
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.5
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    • pp.11-18
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    • 2010
  • This study was conducted to provide design data for deciding covering method in double layers greenhouse. The variation of photosynthetic photon flux (PPF) and heat flow in air inflated and conventional double layers greenhouse was analyzed. The PPF of air inflated double covering greenhouse was less than that of conventional greenhouse during summer season because the more PPF comes into conventional greenhouse through roof vent which was rolled up for ventilation. The air inflated double layers covering greenhouse was superior to conventional type in the aspect of controlling inside temperature down owing to lower irradiation. The PPF of air inflated greenhouse was greater than that of conventional greenhouse during winter season because the transmittance of conventional greenhouse decreased by dust collected on inside plastic film nearly closed for insulation. Considering the PPF not sufficient for tomato growing in winter, the air inflated double covering system with the greater transmittance was better than conventional covering system. When the inside air of air inflated greenhouse was injected into space between the double layers of covering, the PPF of air inflated greenhouse was much less than the conventional greenhouse because the transmittance of air inflated double covering decreased due to condensation of highly humidified inside air. It was concluded that the more dried outside air should be used for inflating double layers covering. The heat insulation performance of air inflated double covering system was superior to conventional double covering system when comparing the overall heat transfer coefficients for each covering method. However the differences among the overall heat transfer coefficients depending on difference between inside and outside temperatures of greenhouse were great, it is necessary to conduct additional experiment for investigating the overall heat transfer coefficient to design the double layers covering.

Vibration Suppression of Smart Structures Using PPF and SRF Control Techniques (PPF와 SRF 제어기법을 사용한 지능구조물의 능동진동제어)

  • 라완규;곽문규;윤광준
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.400-406
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    • 1997
  • This paper is concerned with the active vibration control of grid structure by means of piezoceramic actuators and sensors. The control technique used in this paper is based on the positive position feedback(PPF) and the strain rate feedback(SRF) control, which have been successfully used for the vibration control of beam structures. A new control methodology is developed using the PPF and SRF controller of single-input single-output method. The PPF controller is used for the suppression of first bending mode and SRF controller is used for the suppression of higher vibration modes of grid structure. Electric circuits for the realization of control schemes are explained in detail. The control techniques prove its effectiveness by experiments.

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Vibration Control of Actuators Using Magnetostrictive Materials and PPF Algorithm (자기변형재료와 PPF 알고리즘을 이용한 작동기의 진동제어)

  • Kim, Min-Oug;Hwang, Ho-Yon
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.15 no.3
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    • pp.24-32
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    • 2007
  • In this research, using Terfenol-D actuator composed of magnetostrictive material as shaker and controller, active vibration control theory was applied and verified by experiments. PPF(positive Position Feedback) algorithm which is effective for the control of low frequency vibration was used for the control of a structure. Responses of inputs due to various design variable used for the PPF filter were observed. To investigate the characteristics of magnetostrictive materials, actuator responses were measured for known inputs and satisfactory results were obtained to reduce the vibration level after applying the control input for the actuator.

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MICROBIAL COLONIZATION AND DIGESTION OF FEED MATERIALS IN CATTLE AND BUFFALOES II. RICE STRAW AND PALM PRESS FIBRE

  • Abdullah, N.;Ho, Y.W.;Jalaludin, S.
    • Asian-Australasian Journal of Animal Sciences
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    • v.5 no.2
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    • pp.329-335
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    • 1992
  • Degradation of rice straw was observed to be higher (p<0.01) in the buffaloes than in cattle. At 48 h, the dry matter (DM) loss of straw for buffaloes was 53.6 0.8% and that for cattle was 48.7 2.6%. Palm press fibre (PPF) was poorly degraded in the rumen of both animal species. A loss of about 21% DM was observed in both cattle and buffaloes after 48 h of incubation in the rumen. The pattern of bacterial and fungal colonization of straw and PPF seemed to be similar in both cattle and buffaloes. Microbial colonization was restricted by plant structures like the silica crystals in both straw and PPF. The predominant bacteria colonizing both straw and PPF fragments were the rods. Eroded zones and digestion pits were pronounced in straw fragments after 1 h of incubation. The PPF fragments appeared undegraded even after 6 h of incubation. Fungal colonization of straw was rapid and extensive in both cattle and buffaloes. The sporangia observed in straw were mainly spherical or oval in shape, but fusiform sporangia with acuminate tip were predominantly seen in PPF fragments.