• Smart Structures and Systems
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• 제9권4호
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• pp.303-311
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• 2012

The possibility of suppressing critical speeds by using electromagnetic actuators (EMAs) is assessed experimentally in this paper. The system studied is composed of a horizontal flexible shaft supported by two ball bearings at one end and one roller bearing that is located in a squirrel cage at the other end. Four identical EMAs supplied with constant current are utilized. The EMAs associated to the squirrel cage constitutes the hybrid bearing. Results obtained, show that the constant current, when applied to the EMAs, produces a shift of the first critical speed toward lower values. Moreover, the application of constant current for a speed interval around the critical speed enables a smooth run-up or run-down without crossing any resonance.

• Asian-Australasian Journal of Animal Sciences
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• 제25권4호
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• pp.559-568
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• 2012

White (Lohmann LSL) and Brown (ATAK-S) laying hens, were reared under organic and conventional cage rearing systems, and the effects of the rearing system on performance parameters, egg production, egg characteristics, and immune response were investigated. For this purpose, a total of 832 laying hens of two commercial hybrids, i.e., 416 white (Lohmann LSL) and 416 Brown (ATAK-S) layers, were used. The experiment lasted between 23 and 70 wk of age. In this study, the white layers yielded more eggs as compared to the brown layers in both organic and conventional production systems. Egg weight exhibited a similar pattern to that of laying performance. However, the total hen-housed egg number for the white birds in the organic system was fewer than that of white birds in the conventional cage facility; conversely, a contradictory tendency was observed for the brown birds. Livability of the white layers in the organic system was remarkably lower (14%) than that of the brown line, whereas the white line survived better (3.42%) than their brown counterparts in conventional cages. The feed conversion ratio of the white hens was markedly inferior in the organic system as compared to that of the white hens in the conventional system, whereas relatively lower deterioration was reported in brown layers when reared in an organic system. The organic production system increased egg albumen height and the Haugh unit in eggs of the brown layers. The yolk color score of organic eggs was lower than that of conventional eggs for both brown and white hens. The egg yolk ratio of eggs from white layers was found to be higher in organic eggs as compared to those obtained in the conventional system. All organic eggs had heavier shells than those produced in the conventional system. Eggs from brown layers had more protein content than eggs from white layers. Neither housing systems nor genotype influenced egg yolk cholesterol concentration. When compared to conventional eggs, n-3 fatty acid content was lower in organic eggs, and the n-6:n-3 ratio was higher in organic eggs. In conclusion, two hen genotypes showed different responses in terms of performance and egg quality to two different rearing systems. A commercial white strain produced more eggs with higher egg quality as compared to a native brown strain. The brown strain was found to have adapted well to organic production conditions when survival and total egg number was taken into consideration.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권2호
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• pp.705-713
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• 2021

Because the cage assembly serves as the launch platform, an accurate aim is essential to ensure shooting accuracy for the target. On the other hand, the abnormal rotation of the cage due to the directional errors of the K-MLRS has continuously caused quality problems. The quality problem of weapon systems may have a negative impact on the military's power loss. In this study, improvement plans were derived by examining the defects and analyzing the directional errors of the K-MLRS launcher. In addition, all possible causes of directional errors were derived from the flow diagram for cage directionality. Based on the results, the defense design through the software program was intended to prevent the loss of direction. Through this study, the signal error of the resolver was improved by preventing unspecific signals in the data. Furthermore, the directional judgment method was improved to minimize the impact of data distortion. Lastly, directional storage and verification methods were improved so that data for the cage rotation direction would not be affected by errors. For the design improvement method, the reliability was verified through the system applicability. This study is expected to be a reference for failure analysis and design for similar weapon systems in the future.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.571-575
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• 1986

The squirrel-cage induction motor can be characterized as a nonlinear and multi-input, multi-output system, and has the unmeasurable states which are the rotor currents. In this paper, the time-delayed output feedback method is applied to the speed control of induction motor driven by the current-controlled PWM inverter and its performance is investigated by using the computer simulation.

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.422-428
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• 1998

In the present paper, we report a molecular dynamics (MD) simulation of non-rigid zeolite-A framework only as the base case for a consistent study of the role of intraframework interaction on several zeolite-A systems using the same technique in our previous studies of rigid zeolite-A frameworks. Usual bond stretching, bond angle bending, torsional rotational, and non-bonded Lennard-Jones and electrostatic interactions are considered as intraframework interaction potentials. The comparison of experimental and calculated structural parameters confirms the validity of our MD simulation for zeolite-A framework. The radial distribution functions of non-rigid zeolite-A framework atoms characterize the vibrational motion of the framework atoms. Mean square displacements are all periodic with a short period of 0.08 ps and a slow change in the amplitude of the vibration with a long period of 0.53 ps. The displacement auto-correlation (DAC) and neighbor-correlation (DNC) functions describe the up-and-down motion of the framework atoms from the center of α-cage and the back-and-forth motion on each ring window from the center of each window. The DAC and DNC functions of the framework atoms from the center of α-cage at the 8-ring windows have the same period of the up-and-down motion, but those functions from the center of 8-ring window at the 8-ring windows are of different periods of the back-and-forth motion.

• Bulletin of the Korean Chemical Society
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• 제16권11호
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• pp.1067-1074
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• 1995

Reaction of arachno-S2B7H8- with either THF or 1,2-dimethoxyethane upon refluxing condition results in the formation of the previously known compound hypho-S2B7H10-. Protonation of hypho-S2B7H10- with HCl/Et2O generates hypho-2,5-S2B7H11 in good yield. This hypho-S2B7H10- anion has been employed to generate a series of new nido-, arachno-, and hypho-metalladithiaborane clusters. Reaction of the anion with Cp(CO)2FeCl results in direct metal insertion and the formation of a complex containing the general formula (η5-C5H5)FeS2B7H8. Spectroscopic studies of nido-6-CpFe-7,9-S2B7H8 Ⅰ demonstrated that compound Ⅰ was shown to have an nido-type cage geometry derived from an octadecahedron missing one vertex, with the iron atom occupying the three-coordinate 6-position in the cage and the two sulfurs occupying positions on the open face of the cage. Reaction of hypho-S2B7H10- with CoCl2/Li+[C5H5]- gave the previously known complex arachno-7-CpCo-6,8-S2B6H8 Ⅱ. Also, the reaction of the anion with [Cp*RhCl2]2 gave the complex arachno-7-Cp*Rh-6,8-S2B6H8 Ⅲ, the structure of which was shown to be that of complex Ⅱ. The similarity of the NMR spectra of Ⅱ and Ⅲ suggest that Ⅲ adopts cage structure similar to that previously confirmed for Ⅱ. A series of 9-vertex hypho clusters in which the sulfur atoms are bridged by different species isoelectronic with a BH3 unit, such as HMn(CO)4 or SiR2 have been prepared. Compounds Ⅳ,Ⅴ and Ⅵ are each 2n+4 skeletal electron systems and would be expected according to skeletal electron counting theory to adopt hypho-type polyhedral structures derived from an icosahedron missing three vertices. The complex hypho-1-(CO)4Mn-2,5-S2B6H9 Ⅳ was obtained by the reaction of the anion with (CO)5MnBr and has been shown from spectroscopic data to consist of a (CO)4Mn fragment bound to the two sulfur atoms S2 and S5 of hypho-S2B7H10-. Also, similar hypho-type complexes hypho-1-R2Si-2,5-S2B6H8 (R=CH3 Ⅴ, R=C6H5 Ⅵ) have been prepared from the reaction of hypho-S2B7H10- with R2SiHCl.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 한국퍼지및지능시스템학회 2004년도 추계학술대회 학술발표 논문집 제14권 제2호
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• pp.21-25
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• 2004

This paper suggests the techniques in determining the values of the steady-state equivalent circuit parameters of a three-phase squirrel-cage induction machine using immune algorithm. The parameter estimation procedure is based on the steady state phase current versus slip and input power versus slip characteristics. The proposed estimation algorithm is of a nonlinear kind based on clonal selection in immune algorithm. The machine parameters are obtained as the solution of a minimization of least-squares cost function by immune algorithm. Simulation shows better results than the conventional approaches.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.7-14
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• 2014

Aircraft variable frequency power and a new application of induction motor under the aero-power are introduced. The transient models and simulation of induction motor are reviewed. A new transient model and simulation method is presented that includes deep-bar effect and magnetic saturation. Dynamic magnetizing inductance, rotor resistance and leakage reactance are considered as varying parameters in state-space model. Base on known rotor structure and speed, these parameters can be calculated.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 한국퍼지및지능시스템학회 2006년도 추계학술대회 학술발표 논문집 제16권 제2호
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• pp.163-166
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• 2006

유도전동기는 산업시스템에 있어서 필수적인 요소이기 때문에 유지 관리, 모니터링시스템, 고장 진단 등의 다양한 분야에서 많은 연구가 행해지고 있다. 유도전동기의 운전 중 하나의 고장이 발생한 경우 이것은 전동기의 다른 부분에 영향을 미치거나 또 다른 고장을 유발시키는 원인이 된다. 따라서 개별적인 고장뿐만 아니라 결합된 형태의 고장을 검출하고 진단하는 것은 유용한 방법이다. 본 논문에서는 전압불평형 고장과 회전자바 고장이 발생한 경우, 그리고 두 고장이 동시에 복합적으로 발생한 경우를 모델링하고 이에 대해 고장 진단을 하였다. 제안된 고장 검출 및 진단 알고리즘은 농형운도전동기의 고정자 전류를 이용하였으며 매트랩 시뮬링크를 사용하여 시뮬레이션 하였다.

• Journal of Power Electronics
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• 제7권2호
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• pp.97-108
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• 2007

This paper describes simple control structures for a vector controlled stand-alone induction generator (IG) for use under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with a newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of a PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter while using only three sensors and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltage regulation.