• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.879-884
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• 2009

A Method for detection of saturation of a current transformer(CT) is proposed. The algorithm is initiated when the end point of a saturation period is detected. This detection is achieved by checking the time interval between the adjacent zero-crossing points of the second derivative of the secondary current. Once the end point of the saturation period is detected, the beginning point of the corresponding saturation period is determined by backward examination of the sum of the secondary current from the end point. The performance of the algorithm was evaluated for a-g faults on a 345 kV 100km overhead transmission line. The Electromagnetic Transient Program(EMTP) was used to generate fault current signals for different fault inception angles and different remanent fluxes. The performance evaluation shows that the proposed algorithm successfully detects the saturation period even in the presence of a remanent flux.

• Korean Journal of Medicinal Crop Science
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• v.9 no.3
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• pp.232-237
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• 2001

This study was carried out to know the effect of light intensity, temperature and $CO_2$ concentration on photosynthesis and transpiration in yacon(Polymnia sonchifolia Poepp.& Endl.). Light compensation point was ${58\;{\mu}mol\;m^{-2}\;s^{-1}}$and light saturation point was ${1708\;{\mu}mol\;m^{-2}\;s^{-1}}$. Transpiration rate was increased to about 4 mmol${m^{-2}\;s^{-1}}$ with increasing of light intensity to ${2193\;{\mu}mol\;m^{-2}\;s^{-1}}$. The optimum temperature for photosynthesis was ${24^{\circ}C}$ in air. Photosynthesis was gradually reduced as transpiration rate increased from 4 to 8 mmol ${m^{-2}\;s^{-1}}$ in different air temperature. $CO_2$ compensation point was 63 vpm and $CO_2$ saturation point was 1155 vpm and light saturation point was enhanced with increasing of $CO_2$ concentration from 350 vpm to 1300 vpm.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.752-760
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• 2018

In this paper, interior permanent magnet synchronous motor (IPMSM) design for sensorless drive, considering magnetic neutral point shift according to magnetic saturation, has been proposed. Sensorless control was divided into a method based on inductance and a method based on back induced voltage. Because induced voltage is very small at zero or low speed, error in rotor initial position estimation may occur. Using the ratio of saliency addresses this problem. When using high-frequency injections at low speed, the rotor's initial position is estimated at the smallest portion of the inductance. IPMSM has the minimum inductance at the d-axis. However, if magnetic saturation leads to magnetic neutral point variation, following the load current change, there is a change in the minimum point of inductance. In this case, it can lead to failure of initial rotor position estimation. As a result, it is essential that the blocking design has an inductance minimum point shift. As such, in this study, an IPMSM design method, by blocking magnetic neutral point change, has been proposed. After determining the inductance profile based on the finite element analysis (FEA), the results of proposed method were verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.593-602
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• 2006

This paper propose to methodology for deciding suitable bit size that minimizes hardware complexity and performance degradation from floating-point design the fixed-point implementation of downlink traffic channel of IEEE 802.16e OFDMA TDD system. One of the major considering issues for implementing fixed-point design is to select Saturation or Quantization properly with the knowledge of signal distribution by pdf or histogram. Also, through trial and error, we should execute exhaustive computer simulation for various bit sizes, hence obtain appropriate bit size while minimizing performance degradation. We carry out computer simulation to decide the optimized bit size of downlink traffic channel under AWGN and ITU-R M.1225 Veh-A channel model.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.88-90
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• 2003

In this paper, an algorithm to compensate the distorted signals due to CT(Current Transformer) saturation is suggested. Firstly, WT(Wavelet Transform) is used to detect a start point and an end point of saturation. Filter banks which can be easily realized in real-time applications are employed in detecting CT saturation. Secondly, least-square curve fitting method is used to restore the distorted section of the secondary current. Fault simulations are performed on a power system model using EMTP(Electromagnetic Transient Program). A series of test results indicate that WT has superior detection accuracy and the proposed algorithm which shows very stable features under various levels of remanent flux is also satisfactory.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.96-98
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• 2005

In this paper, an algorithm to compensate the distorted signals due to Current Transformer(CT) saturation is suggested, First, DWT which can be easily realized by filter banks in real-time applications is used to detect a start point and an end point of the saturation. Secondly, For enough Datas those need to use the least-square curve fitting method, the distorted current signal is compensated by the AR(autoregressive) model using the data during the previous healthy section until pick point of Saturation. Thirdly, the least-square curve fitting method is used to restore the distorted section of the secondary current. Finaly, this algorithm had a Hadware test using DSP board(TMS320C32) with Doble test device. DWT has superior detection accuracy and the proposed compensation algorithm which shows very stable features under various levels of remanent flux in the CT core is also satisfactory. And this algorithm is more correct than a previous algorithm which is only using the LSQ fitting method. Also it can be used as a MU involving the compensation function that acquires the second data from CT and PT.

• Korean Journal of Medicinal Crop Science
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• v.10 no.1
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• pp.1-4
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• 2002

This study was carried out to know the effect of light intensity, temperature and $CO_2$ concentration on photosynthesis and transpiration in Hovenia dulcis Thunb. Light compensation point was $2.4\;{\mu}mol\;m^{-2}\;s^{-1}$ and light saturation point was $1033\;{\mu}mol\;m^{-2}\;s^{-1}$. The optimum temperature for photosynthesis was $25^{\circ}C$ at $1000\;{\mu}mol\;m^{-2}\;s^{-1}$ light intensity. $CO_2$ compensation point was 67 vpm and $CO_2$ saturation point was 707 vpm. Transpiration rate was increased to about $2\;mmol\;m^{-2}\;s^{-1}$ with increasing of light intensity to $1750\;{\mu}mol\;m^{-2}\;s^{-1}$ and to above $4\;mmol\;m^{-2}\;s^{-1}$ with increasing of temperature from $18^{\circ}C$ to $36^{\circ}C$. however It was gradually reduced as $CO_2$ concentration increased from 21 vpm to 800 vpm.

• Child Health Nursing Research
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• v.13 no.3
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• pp.299-307
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• 2007

Purpose: To investigate the effect of nonnutritive sucking(NNS) on the heart rate, oxygen saturation, and behavioral state of premature infants. Method: From December 15, 2004 to February 15, 2005, 20 premature infants hospitalized in the neonatal intensive care units were assigned to an experimental group (10), or a control group (10). Circular pacifiers for premature infants (Johnson, U.S.A.), which had been packed with $2{\times}2$ gauzes to create a vacuum, were used for 5 minutes, one hour after feeding for 5 days. Heart rates and oxygen saturation were checked every minute for 10 minutes once a day and behavioral states were monitored through video recording at the same time. Results: Changes in heart rate, oxygen saturation and behavioral state were found to show significant differences between the experimental group and the control group according to the point in time, and interactions were found between the group and the point of time. However, for behavioral state, no significant difference was found between the experimental group and the control group after the NNS was removed. Conclusion: From the results of this study it is possible to conclude that NNS is a positive intervention to bring about increased oxygen saturation and soothed behavioral state for premature infants.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.326-328
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• 2009

we an autotuning algorithm for PI controller with unknown plant. The proposed algorithm uses a saturation function and time delay element as a test signal. Since the integral element of PI controller reduces a phase margin and amplitude margin in the closed loop system, the closed loop system could be resulted in unstable with PI controller, To avoid unstable in the closed loop system with PI controller, the proposed algorithm identifies one point information in the 3rd quadrant of Nyquist plot with a time delay element. The proposed method improves an accuracy of one point identified information with one saturation function.

• Journal of IKEEE
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• v.11 no.4
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• pp.193-197
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• 2007

We use a saturation function with memory instead of a pure saturation function to generate a limit cycle in order to find one point information of a plant in the frequency domain. The saturation function with memory is useful in the presence of noise and/or a short duration of short duration of external disturbances. We analyze the error caused by the approximation that the saturation function with memory treated as a pure saturation function. We propose a new tuning formula for PID controller which can be applied a saturation function having memory with an arbitrary memory size. We show that the proposed method is more accurate than that of the approximation method via an example.