• Journal of IKEEE
• /
• v.23 no.2
• /
• pp.543-551
• /
• 2019

Permanent Magnet Synchronous Motors(PMSMs) have a wider range of applications due to their high output density and high efficiency. PMSMs are used not only in high-power density, high-performance motor-driven systems such as vehicle and robots, but also in systems where cost-cutting is very important, such as washing machines, air conditioners and refrigerators. To reduce costs, position sensorless control is required, which is generally difficult to be used under conditions of starting the motor. Thus, the I-F speed control that rotates the current vector at any speed in the starting procedure should be used at first, and then the sensorless speed control could be applied after PMSM rotates above a certain speed. Speed control performance in I-F speed control and sensorless speed control is very important. And more speed control performance should be maintained even in the transient in which the two control techniques are changed. In this paper, the speed controller transition method from I-F speed control to sensorless speed control of permanent magnet synchronous motor is proposed. Experiments were carried out on the washing machine drive system to verify the performance of the proposed technique.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.5
• /
• pp.395-403
• /
• 2020

This study presents a stable start-up strategy for v/f scalar-controlled permanent magnet synchronous motors (PMSMs). The v/f-controlled PMSMs easily lose synchronism under low-speed conditions if an insufficient stator voltage is applied to the machine due to errors in measured motor parameters and inverter nonlinearity, such as inverter dead time and on-state voltage drop. The proposed method adopts the I/f control method to ensure a stable start at low speeds and then switches to the v/f control method at medium speeds. A smooth transition method from I/f control to v/f control is proposed to minimize the oscillation of the stator current and rotor speed during transition. Moreover, the stability of the I/f and v/f control methods is analyzed using a small-signal model. Simulation and experimental results are provided to verify the performance of the proposed control strategy.

• Smart Structures and Systems
• /
• v.21 no.6
• /
• pp.777-791
• /
• 2018

This paper discusses the shape control of deformable mirrors for Adaptive Optics in the dynamic range. The phenomenon of control-structure interaction appears when the mirror becomes large, lowering the natural frequencies $f_i$, and the control bandwidth $f_c$ increases to improve the performance, so that the condition $f_c{\ll}f_i$ is no longer satisfied. In this case, the control system tends to amplify the response of the flexible modes and the system may become unstable. The main parameters controlling the phenomenon are the frequency ratio $f_c/f_i$ and the structural damping ${\zeta}$. Robustness tests are developed which allow to evaluate a lower bound of the stability margin. Various passive and active strategies for damping augmentation are proposed and tested in simulation.

• Communications for Statistical Applications and Methods
• /
• v.4 no.1
• /
• pp.139-149
• /
• 1997

For split plot designs exact univariate F tests of the within-subjects main effect are based on the assumption of multisample sphericity. Type I error rates and power are reported for the F test and two tests designed for use when multisample sphericity is violated: the $\widetilde{\xi}$-adjusted test and the Corrected Improved General Approximation(CIGA) test.The results indicate that even though the F test and the $\widetilde{\xi}$-adjusted test have better power than the CIGA test in some conditions, the F test and the $\widetilde{\xi}$-adjusted test do not control Type I error rates when the design is unbalanced and the F test dose not have a good control of Type I error rates when sphericity assumption is severely violated.

• Bulletin of the Korean Mathematical Society
• /
• v.37 no.2
• /
• pp.229-247
• /
• 2000

This paper is concerned with the impulsive Cauchy problem where the control function u is a possibly discontinuous vector-valued function with finite total variation. We assume that the vector fields f, $g_i$(i=1,…, m) are dependent on the time variable. The impulsive Cauchy problem is of the form x(t)=f(t,x) +$\SUMg_i(t,x)u_i(t)$, $t\in$[0,T], x(0)=$\in\; R^n$, where the vector fields f, $g_i$ : $\mathbb{R}\; \times\; \mathbb{R}\; \longrightarrow\; \mathbb(R)^n$ are measurable in t and Lipschitz continuous in x, If $g_i's$ satisfy a condition that $\SUM{\mid}g_i(t_2,x){\mid}{\leq}{\phi}$ $\forallt_1\; <\; t-2,x\; {\epsilon}\;\mathbb{R}^n$ for some increasing function $\phi$, then the imput-output function can be continuously extended to measurable functions of bounded variation.

• Journal of fish pathology
• /
• v.33 no.1
• /
• pp.83-89
• /
• 2020

In the study, we investigated the effect of Taurine-F^TM, which is a commercially available fishery nutritional supplements complex, on anti-hepatotoxicity stressed with thioacetamide (TAA) and innate immune responses in olive flounder. To investigate the change in liver toxicity, firstly, TAA (30 ppm/100 g of fish) was intraperitoneally (i.p.) administered 12 hr after the intramuscular (i.m.) injection of Taurine-F^TM (0.02 ml/100 g of fish)(Taurine/TAA). Secondly, Taurine-F^TM was i.m. injected 24 hr after the administration of TAA (TAA/Taurine). Finally, TAA was administered simultaneously with Taurine-F^TM (TAA+Taurine). All blood samples were collected 24 hr after injection. GOT level in group Taurine/TAA appeared similar to the control, whereas group TAA/Taurine and TAA+Taurine showed significantly increased (p<0.05) levels compared to the control. In GPT level, group Taurine/TAA and TAA/Taurine showed elevated levels compared to the control, whereas no significant difference was observed between group TAA+Taurine and the control. Serum ACH₅₀ activity was significantly (p<0.05) augmented 24 hr after Taurine-F^TM injection compared to the control group, whereas no significant increase was observed 48 hr after Taurine-F^TM injection. On the other hand, serum lysozyme activity elevated in an acute stressed condition appeared significantly down-regulated 24 and 48 hr after Taurine-F^TM injection compared to the control. In conclusion, i.m. injected Taurine-F^TM augmented flounder serum complement activity and decreased a possible handling stress resulting in reducing a serum lysozyme activity and recovering hepatotoxicity. Thus, it is assumed that i.m. injection of Taurine-F^TM mixed with antibiotics or available vaccines could be utilized as an anti-hepatotoxic recipe in fish culture industry.

• Journal of the Korean Society of Systems Engineering
• /
• v.12 no.2
• /
• pp.9-18
• /
• 2016

Machine switch type control panel is widely used for machine tools in Korea. They, however, have some difficulties in identifying the current operating status of machine tools especially when exposed to cutting oil. And also they have quality problems of operating failures. A new capacitor touch type machine control panel is developed and its reliability is predicted. MIL-HDBK-217F and Teclordia SR-332 are used for its reliability prediction and the prediction results are compared.

• Proceedings of the KIPE Conference
• /
• 2009.11a
• /
• pp.271-273
• /
• 2009

Because few signals are generated using low resolution position sensor at low speed, rotor position estimation is difficult in drum washing machine application. Besides, inertia of water and drum affect the initial operation load up to two times of rated load. Therefore overcurrent can be occurred at initial operation. In this paper, IPMSM vector control for drum washing machine is proposed by applying I/F initial operating method and sensorless control. And we verify the performance through experiment.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.4
• /
• pp.412-418
• /
• 2014

This paper describes the development of variable stability system (VSS) control laws for the KFA-i to simulate the dynamics of KFA-m aircraft. The KFA-i is a single engine, Class IV aircraft and was selected as an in-flight simulator (IFS) aircraft, whereas the KFA-m is a simulated aircraft that is based on the F-16 aircraft. A 6-DoF math model of KFA-i aircraft was developed, linearized, and separated into longitudinal and lateral motion for VSS control law synthesis. The KFA-i aircraft has five primary control surfaces: two flaperons, two all movable horizontal tails, and one rudder. Flaperons are used for load control, the horizontal tails are used for pitch and roll rate control, and the rudder is used for yaw rate control. The developed VSS control law can simulate four parameters of the KFA-m aircraft simultaneously, such as pitch, roll, yaw rates, and load. The simulation results show that KFA-i follows the responses of KFA-m with high accuracy.

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.1
• /
• pp.91-96
• /
• 2006

The experiment was conducted to study the effect of choice feeding on growth performance, carcass quality, gastrointestinal development and feed utilization of 22-49 days old broilers. One hundred and forty four 22-day-old broilers were randomly allocated to 3 treatments with 4 replicates per treatment and 12 birds per replicate. Three feeding regimes are complete diet (control), ground corn and protein concentrate (treatment I), and soybean meal and balancer (treatment II). Protein concentrate is the residue part of complete diet without corn, and balancer is the residue part of complete diet without soybean meal. Treatment I and II are designed for the broilers to freely choose the two parts of diet. The results showed that: (1) broilers under choice feeding (treatment I and II) had lower performances compared with the control; (2) gastrointestinal development and the efficiency ratios that broilers converted dietary crude protein and lysine to body weight gain were improved in treatment I (p<0.05); (3) there were no significant differences in the apparent metabolizabilities of dietary dry matter, crude protein and gross energy, and deposition ratios of dietary nitrogen and energy, and carcass quality among three feeding regimes (p>0.05).