• Korean Journal of Poultry Science
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• v.21 no.4
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• pp.257-266
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• 1994

Three protein feeding systems for egg-type pullets involving conventional step-down protein 18-15-12%), step-up protein(12-15-18%) and single-stage low protein (13-13-13%) with an iso-energy level of 2,900 ME kcal /kg were compared to examine the effect on pullet growth and subsequent laying performance. During the growing period, pullets subjected to the step-up and single-stage low protein feeding systems were lighter in body weight and consumed less feed and netabolizable energy than those on the conventional step-down protein feeding system(P<0.05). 3ut the pullets on the step-up protein diet consumed more protein, and those on the single-stage low protein diet consumed less protein than those on the step-down protein diet(P<0.05). Also, he feed cost was less in pullets on the single-stage low protein diet than in those on the other systems(P<0.05). During the laying period, sexual maturity was later in hens reared on the step-up and single-stage low protein diets than in those on the step-down protein diet(P<0.05), however, average hen-day egg production and egg weight were not significantly affected by the protein feeding systems in the growing period. Daily feed intake and feed required per egg were significantly reduced in hens on the single-stage low protein diet compared to those on conventional protein feeding system(P<0.05). It was concluded that the 13% single-stage low protein feeding system produced smaller pullets with less feed, energy, protein, and feed cost during the growing period, and hens reared on that system consumed less feed during the laying period without any impairment of production compared to the conventional rearing system.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.56-63
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• 1997

There generally exists a large variation in the thereshold voltages of the flash EEPROM cells after they are erased by using th fowler-nordheim tunneling, thereby getting some cells to be overeased. If the overerased cells are programmed with the conventional one-step programming scheme where an 12-13V pulse with the duration of 100.mu.S is applie don the control gate for the programming, they can suffer from the significant degradation of the reliability of the gate oxide. A two-step programming schem, where an 8/12 V pulse with a duration of 50.mu.S for each voltage is applied on the control gate for the programming, has been studied to solve the problem. The experimental results hav eshown that there is little difference in the programming characteristics between those two schemes, whereas the degradation of the gate oxide due to the programming can be significantly reduced with the two-step programming scheme compared to that with the one-step programming scheme. This is possibly because the positive charge stored in the floating gate of the overerased cells is compensate dwith the electrons injected into the floating gate while the 8V pulse is applied on the control gate, which leaves the overerased cells in the normally erased state after the duration of the 8V pulse.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.6
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• pp.547-553
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• 1999

A new multi-step voltage source inverter is proposed in this paper. The proposed scheme is composed of t the double-connected 12-step inverter with an auxiliary circuit. The auxiliary circuit includes two voltage d dividing capacitors, two switching devices and a low KV A autotransformer. The resultant system is shown to b be a 24-step inverter suitable for medium power level SVC applications in which the PWM method can not be e employed. A 36-step operation can also be 이)tained by the addition of a bidirectional switch to the ProlXlsed I inverter. The design parameters are derived from the analysis of voltages and currents by means of switching f functions. The validity of the proposed scheme is confirmed by the simulated and experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4147-4152
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• 2011

Compared to the constant modulus algorithm (CMA), the modified CMA (MCMA) is easy not only to improve the steady-state performance but also to be expanded to higher-order constellations by using fewer moduli with evenly spaced. In this paper, it is shown that the MCMA is sufficient to achieve satisfactory steady-state performance by applying a variable step-size to the MCMA without switching to an hard decision-directed algorithm. Two new methods varying the step-size are proposed, and the performance improvement of the MCMA with the new methods of variable step-size is presented as compared to the CMA and the fixed step-size MCMA through computer simulations.

• Journal of Power Electronics
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• v.12 no.1
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.156-163
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• 2010

The brushless motor is getting widely applied to the automotive component with the advantage of the high efficiency, high reliability and etc.. Most of the motor applications require the low vibration and acoustic noise. The cogging torque is the one of the main cause of the noise and vibration. The step-skewed rotor is used to reduce the cogging torque. We analyze the characteristics of the step-skewed rotor and non skewed rotor with the same stator by using 2-dimensional FEM. And then we analyze the characteristics variation according to the rotor eccentricity. The prototype is made and tested. As the results, the step-skewed rotor structure reduce the cogging torque and local radial force but it is more sensitive to rotor eccentricity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1201-1207
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• 2006

This paper introduces a step motor with a passively levitated rotor which comprises a homopolar step motor and a passive magnetic bearing. Compared with conventional self-bearing motors which are mostly based on the active magnetic bearing technology, the proposed motor has a very simple structure and operating principle. For the levitation, it works just like passive magnetic bearings which use the repulsive force between permanent magnets. Halbach array is used to increase the bearing stiffness. On the other hand, its rotation principle is just the same with that of conventional motors. In this paper, we introduce the design scheme to avoid the flux interference possibly produced by electromagnets and permanent magnets, and show some results of FEM analysis to predict the performance of the proposed motor.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1189-1196
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• 2010

This paper provides an identification method for three-parameter models i.e. first order with dead time models and second order with dead time models. The proposed identification method is based on step response and can be easily implemented using digital microprocessors. The proposed method first identifies the order of the plant i.e. first order or second order from the behavior of the plant with constant input. After the order of the plant is determined, a test step input is applied to the system and the three parameters of the plant are obtained from the corresponding response of the plant. The output of the plant need not to be zero when the test signal is applied. The efficacy of proposed algorithms is verified through simulation and experiment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.12
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• pp.2047-2054
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• 2003

In this paper, an approach of automatically finding and modifying the most appropriate orthogonal array (GO) is suggested and applied to a new structural optimization procedure with two steps. GO is motivated by the situation where finding a proper orthogonal array from the tables in the literature is difficult or impossible. Now the Taguchi method is made available for various numbers of variables and levels. In the two-step structural optimization, the Taguchi method equipped with GO and a shape optimization using the finite differencing method is consecutively applied. The existence or non-existence of an element can be taken as a factor level and this feature is utilized finding the best topology from a set of potential topologies suggested from the user's expertise. This greatly enhances applicability and one can expect a better result than the case in which each step is applied independently because these steps are complementary each other.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.36-41
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• 2004

In this paper a large scale STATCOM using double-connected multi-step inverter is proposed and operating principle along with control method is detailed. A simple auxiliary circuit including an interphase transformer is employed to improve output voltage waveform of 12-step into 36-step. The proposed scheme could be a cost effective approach in high power applications such as 10MVar to 30MVar STATCOM. Experimental results from a 2KVA laboratory prototype show validity of the proposed method.