• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.2
• /
• pp.30-37
• /
• 2012

Pneumatic Active Engine Mount(PAEM) with open-loop control system has been developed to reduce the transmission of the idle-shake vibration induced by engine effectively and economically. A solenoid valve installed between PAEM and vacuum tank is on-off switched by the Pulse Width Modulate(PWM) control signal to decrease the dynamic stiffness of the engine mount. This paper presents the methodology to identify the optimal values of control parameters of a PAEM, i.e, turn-on timing and duty ratio of PWM signal for 6 different idle driving conditions. A scanning algorithm was first applied to the vehicle test to obtain the approximate optimal control parameters minimizing the vibration at front seat rail and at steering wheel. Then the PAEM system identification was fulfilled to find accurate optimal control parameters by using multi-layer neural networks of Levenberg-Marquardt algorithm with vehicle test data.

• Korean journal of food and cookery science
• /
• v.31 no.6
• /
• pp.687-695
• /
• 2015

The purpose of this study was to investigate the quality characteristics of cookies prepared with wheat sprout powder substituted at varying proportions (0%, 2%, 4%, 6%, and 8%) for wheat flour. The bulk density of cookie dough with wheat sprout powder were higher than that of the control group and the pH decreased. The moisture content of the groups with wheat sprout powder was higher than the control group. Width and thickness of finished cookies containing wheat sprout powder were lower than those of the control group. The spread ratio of the group with 8% wheat sprout powder was higher than that of the control group. In color, the L and a value decreased significantly with addition of wheat sprout powder. The hardness of the study groups was lower than that of the control group. DPPH radical scavenging activity of the control group was 24.90%, whereas the study groups ranged from 27.53~38.76%. Sensory evaluation scores in terms of appearance, texture, taste and overall preference of groups with 2% and 4% of wheat sprout powder did not show any significant difference when compared to the control group. Based on the above results, using less than 4% of the wheat sprout powder would be appropriate for use in cookies.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2099-2108
• /
• 2016

The cascaded multilevel converter is widely adopted to medium/high voltage and high power electronic applications due to the small harmonic components of the output voltage and the facilitation of modularity. In this paper, the operation principle of a T-type H-bridge topology is investigated in detail, and a carrier phase shifted pulse width modulation (CPS-PWM) based control method is proposed for this topology. Taking a virtual five-level waveform achieved by a unipolar double frequency CPS-PWM as the output object, PWM signals of the T-type H-bridge can be obtained by reverse derivation according to its switching modes. In addition, a control method for the T-type H-bridge based cascaded multilevel converter is introduced. Then a single-phase T-type H-bridge cascaded multilevel static var generator (SVG) prototype is built, and a repetitive controller based compound current control strategy is designed with the DC-link voltage balancing control scheme analyzed. Finally, simulation and experimental results validate the correctness and feasibility of the proposed modulation method and control strategy for T-type H-bridge based cascaded multilevel converters.

• Advances in aircraft and spacecraft science
• /
• v.1 no.4
• /
• pp.427-441
• /
• 2014

Orbit-raising is an important step to place spacecraft from parking orbits into working orbits. Attitude control system design is crucial in the success of orbit-raising. Several text books have discussed this design and focused mainly on the traditional methods based on single-input single-output (SISO) transfer function models. These models are not good representations for many orbit-raising control systems which have multiple thrusters and each thruster has impact on the attitude defined by all outputs. Only one published article is known to use a more suitable multi-input multi-output (MIMO) Euler angle model in spacecraft orbit-raising attitude control system design. In this paper, a quaternion based MIMO model for the orbit-raising attitude control system design is proposed. The advantages of using quaternion based model for orbit-raising control system designs are (a) there is no need for mathematical transformations because the attitude measurements are normally given by quaternion, (b) quaternion based model does not depend on rotational sequences, which reduces the chance of human errors, and (c) the singular point of reduced quaternion model is the farthest from the operational point where linearization is performed. We will show that performance of quaternion model based design will be as good as the performance of Euler angle model based design for orbit-raising problem.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.5
• /
• pp.505-511
• /
• 2011

In this paper, we have developed an automatic velocity control system of a small-sized commercial treadmill (belt length of 1.2 m and width of 0.5 m) which is widely used at home and health centers. The control objective is to automatically adjust the treadmill velocity so that the subject's position is maintained within the track when the subject walks at a variable velocity. The subject's position with respect to a reference point is measured by a low-cost sonar sensor located on the back of the subject. Based on an encoder sensor measurement at the treadmill motor, a state feedback control algorithm with Kalman filter was implemented to determine the velocity of the treadmill. In order to reduce the unnatural inertia force felt by the subject, a predefined acceleration limit was applied, which generated smooth velocity trajectories. The experimental results demonstrate the effectiveness of the proposed method in providing successful velocity changes in response to variable velocity walking without causing significant inertia force to the subject. In the pilot study with three subjects, users could change their walking velocity easily and naturally with small deviations during slow, medium, and fast walking. The proposed automatic velocity control algorithm can potentially be applied to any locomotion interface in an economical way without having to use sophisticated and expensive sensors and larger treadmills.

• Applied Microscopy
• /
• v.32 no.3
• /
• pp.223-230
• /
• 2002

Vitamin D is one of important factors involved in the regulation of bone metabolism. In osteoporosis, the therapeutic effect of vitamin D on the healing process has still been controversial. To confirm the effects of $1{\alpha},\;25\;Dihydroxyvitamin\;D_3$ on the osteoporosis, the change of bone mineral density and the histologic changes of osteoporotic femur were examined comparatively in normal control group (positive control), CFA control group (negative control), CFA+$1{\alpha}$, 25 dihydroxyvitamin $D_{3}\;0.01{\mu}g/kg$ group (Vit $D_{3}L$) and CFA+$1{\alpha}$, 25 dihydroxyvitamin $D_{3}\;0.1{\mu}g/kg$ group (Vit $D_{3}H$) after osteoporosis was induced by single injection of complete Freund's adjuvant (CFA) in rats. The value of bone mineral density and bone mineral content of femur was increased in both Vit $D_{3}L$ and Vit $D_{3}H$ than CFA control, and the increase rate of that was higher in Vit $D_{3}H$ than Vit $D_{3}L$. In CFA control, the size of the bone marrow cavities significantly increased and the width from the bone marrow cavity and cortex significantly decreased than normal control. In Vit $D_{3}H$ and Vit $D_{3}L$, the increase rate of the size of bone marrow cavity and the decrease rate of the width from the bone marrow cavity and cortex was depressed than CFA control. These results suggest that $1{\alpha},\;25\;Dihydroxyvitamin\;D_3$ has therapeutic effect on adjuvant-induced osteoporosis in rats.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.11B no.4
• /
• pp.169-174
• /
• 2001

A novel simulation scheme of transient phenomenon for the photovoltaic (PV) generation system under the real weather conditions has been proposed in this paper. A grid connected PV array is simulated using PSCAD/EMTDC. The transient changes of the output current of PV array under the real weather conditions is described and the output current of DC/AC converter flowing through the utility power network is also analyzed with the PWM switching width. Moreover, the MPPT control of PV generation system is combined to the system during the simulation for the comparison purposes of the control schemes. The outcome of the simulation demonstrates the effectiveness of the proposed simulation scheme. The result shows that the cost effective verifying for the efficiency or availability and stability of PV generation systems and the comparison research of various control schemes like MPPT under the same real whether conditions are eventually possible.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1953-1955
• /
• 1999

The effects of the local lifetime control on the characteristics of IGBT are investigated using the 2-dimensional device simulator, MEDICI. Many lumped resistive turn-off simulations are carried out to analyze the effects of the minority carrier lifetime, the width, and the position of the region with a reduced local minority carrier lifetime. As a result of these simulations, it is concluded that the on state voltage drop$(V_{CE,SAT})$ is only slightly increased while the switching behavior is greatly improved if the low lifetime region is properly set. And these results are compared with IGBTs having uniform lifetime.

• Journal of information and communication convergence engineering
• /
• v.8 no.2
• /
• pp.205-211
• /
• 2010

In this study, a Magnetic stimulation Pulse Train control technique is introduced and applied to Flyback converter operating in discontinuous conduction mode. In contrast to the conventional pulse width modulation control scheme, the principal idea of a Magnetic stimulation Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in discontinuous conduction. However, this work mainly focuses on Flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.27 no.1
• /
• pp.53-60
• /
• 2013

In this paper, a control algorithm for active power filter (APF), which compensates for the harmonics and power factor, boosting the DC-link voltage is proposed. The proposed scheme employs a pulse-width-modulation (PWM) voltage-source inverter. A simple algorithm to detect the load current harmonics is also proposed. The APF and charging circuit are implemented in one inverter system. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype APF system rated at 3kVA.