• Bulletin of the Korean Chemical Society
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• v.9 no.3
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• pp.164-166
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• 1988

7-Dithiocarboxy-3-phenyl-5,6-dihydro imidazo[2,1-b]thiazolium-betaine (2) was prepared by treatment of 3-phenyl-5,6-dihydro imidazo[2,1-b]thiazole (1) with carbon disulfide in acetone at room temperature. On the reaction of 2 with para-substituted phenacyl bromides (4) having the electron withdrawing property by virtue of (+) resonance (R) < (-) inductive (I) or (-) resonance (R), (-) inductive (I) effect, ring transformation product p-substituted-2-[2-[7-(p-substituted benzoyl)-5-thioxo-2,3-dihydro-1H-imidazo[1,2-c] thiazol-1-yl]-2-phenylvinylthio] acetophenone (6) was obtained; however, when R is electron donating grops with (+) resonance (R) > (-) inductive (I) effect the quarternary ammonium salt 7-(p-substituted phenyl) carbonyl methyl-3-phenyl-5,6-dihydro imidazo [2,1-b] thiazolium bromide (8) is formed. The reaction of 2 with unsubstituted-phenacyl bromide (R = H), on the other hand, gives 6a and 8a to the similar ratio, respectively.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.104-108
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• 2014

This paper represents the effect analysis results of surface-Icing on the UHF-band antenna for Space Launch Vehicle. In order to obtain structural model of the surface-icing, Relative Permittivity of ice at $-180^{\circ}C$ was extracted. Using this surface-Icing model, UHF-band antenna simulation and comparative analysis about the antenna parameters such as resonance frequency, reflection loss and radiation pattern were performed for each case of with or without surface-icing. Simulation results show that resonance frequency is shifted out of operation frequency due to the additional ice permittivity. This resonance frequency changes cause severe affect to the antenna performance and its radiation pattern.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.44-51
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• 2006

In this paper, the resonance characteristics of zigzag wire dipole antennas are first analyzed by the method of moment(MOM) for shortening the space occupation length of straight wire dipole antenna Considering the shortening effect the integrated zigzag dipole antennas with the simplified microstrip feed are designed. Since the integration gives rise to discontinuities due to antenna line width with abrupt bend angles, the compensation by the chamfer is applied. Futhermore the integrated parasitic zigzag lines are properly attached to both sides of substrate for compensation of the effect of the dielectric substrate, hence improving the resonance characteristic. The design results at UHF and ISM band are verified with experiments.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.641-650
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• 2018

Purpose: This article provides a cause of breakage and a method for improving reliability of the headlight system installed in the main battle tank K2. Method: The natural frequency of the headlight system is estimated by using the finite element method. In addition, the allowable stress level under the severe conditions is provided through vibration test of a single item and a system level. Results: Based on the finite element analysis and the vibration test in the frequency domain, the lamp of the left headlight system fails by the resonance effect. Conclusion: For improving the reliability of the headlight system, the thickness of protector frame is increased to avoid the resonance effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1596-1600
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• 2000

We propose a novel adaptive feed forward controller (AFC) design method for rejecting the effect of micro actuator resonance in the design of dual-stage actuator servo systems for disk drives. Microactuator's resonance is one of important issues in dual-stage actuator servo, which varies up to ${\pm}10%$ per product and even during operation. We derive an adaptive algorithm for the proposed AFC design, which turns out to be identical to the delayed-x LMS algorithm which is a special form of the filtered-x LMS algorithm. In the algorithm, coefficients of the AFC are adapted by the residuals of constrained structure defined in such a way that the coefficients become time invariant. Contrary to the conventional AFC, it considers the phase delay of closed-loop transfer function at resonance frequency for system stability. We also apply an adaptive algorithm with frequency tracking capability. The frequency tracking algorithm is induced by the orthogonality of AFC coefficients. Computer simulations are carried out to demonstrate effect of the proposed AFCs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.728-734
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• 2000

An asymmetric actuator can be used to reduce the distance between the reflective mirror and objective lens of a small optical disk drive for use in the notebook-sized personal computer data storage devices. However, this asymmetric actuator is very sensitive to the subsidiary resonance which is caused by its rigid body motion. In this paper, an analytical approach using a simple lumped parameter system model is presented with a physical insight to investigate why the subsidiary resonance occurs. The finite element method is used to figure out the force and torque characteristics of the asymmetric actuator which are essential to understand the subsidiary vibration characteristics. The frequency responses are presented to examine how the subsidiary resonance is altered for various situations of having different thickness of a yoke and permanent magnet and of having a different magnet circuit. Finally, the design guidelines to avoid the subsidiary resonance will be presented.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.54-54
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• 2010

Interplanetary space is filled with dust particles originating mainly from comets and asteroids. Such interplanetary dust particles lose their angular momentum by olar radiation pressure, causing the dust grains to slowly spiral inward Poynting-Robertson effect). As dust particles move into the Sun under the influence of Poynting-Robertson drag force, they may encounter regions of resonance just outside planetary orbits, and be trapped by their gravities, forming the density enhancements in the dust cloud (circumsolar resonance ring). The circumsolar resonance ring near the Earth orbit was detected in the zodiacal cloud through observations of infrared space telescopes. So far, there is no observational evidence other than Earth because of the detection difficulty from Earth bounded orbit. A Venus Climate Orbiter, AKATSUKI, will provide a unique opportunity to study the Venusian resonance ring. It equips a near-infrared camera for the observations of the zodiacal light during the cruising phase. Here we consider whether Venus gravity produces the circumsolar resonance ring around the orbit. We thus perform the dynamical simulation of micron-sized dust particles released outside the Earth orbit. We consider solar radiation pressure, solar gravity, and planetary perturbations. It is found that about 40 % of the dust particles passing through the Venus orbit are trapped by the gravity. Based on the simulation, we estimate the brightness of the Venusian resonance ring from AKATSUKI's locations.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.5
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• pp.488-491
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• 2005

A 3-year-old female, 5kg, Shih-tzu developed an acute onset of depression, disorientation, hypersalivation, nystagmus after falling down 2 meter height place. In plain skull radiography, there was fracture line in the frontal and parietal bones and next day magnetic resonance imaging examination was performed. Magnetic resonance imaging of the brain was performed with 3.0 Tesla unit. Under general anesthesia, the dog was placed in prone with its head positioned in a birdcage coil. Transverse, sagittal and coronal fast spin echo images of the brain were obtained with the following pulse sequences: T1 weighted images (TR = 560 ms and TE = 18.6 ms) and T2 weighted images (TR = 3500 ms and TE = 80 ms). Magnetic resonance imaging showed epidural hematoma in the left frontal area resulting in compression of the adjacent brain parenchyma. Left lateral ventricle was compressed secondarily and the longitudinal fissure shifted to the right, representing mass effect. The lesion was iso-to slightly hyperintense on T1 weighted image and iso-slightly hypointense signal on T2 weighted image. At necropsy, there was a skull fracture and epidural hematoma in the left frontal area. Magnetic resonance imaging of epidural hematoma is reviewed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.9
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• pp.847-852
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• 2007

Design aspects of a bearing casing system of a power plant are mainly focused on the strength and weight of itself to have a more stable system. Since the rotor speed often passes through the critical speed region when the operation begins, the relation between the rotating frequency of the rotor and natural frequency of the casing is very important for a prevention of resonance. However, harmonic components above the rotating frequency have often been overlooked the design for the resonance avoidance. In this paper, it is revealed that resonance vibration is generated when the natural frequency of a bearing casing is close to the one of harmonics of basic rotating frequency(1x), and as a consequence, sensing qualify of seismoprobes attached to the bearing casing structure can be seriously damaged. In order to reduce the resonance vibration, some stiffeners are added to the casing structures. Significant reduction in the magnitude of vibration corresponding to 2x harmonic of basic rotating frequency is observed from both FE analysis and experiment.

• Journal of the Korean Society of Visualization
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• v.18 no.1
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• pp.26-37
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• 2020

Magnetic resonance thermometry (MRT) is a technique capable of measuring three-dimensional mean temperature fields by utilizing temperature-dependent shifts in proton resonance frequency. In this study, experimental verification of the technique is obtained by measuring 3D temperature fields within fully developed turbulent pipe flow, using 3T and 7T MRI scanners. The effect of the proton resonance frequency (PRF) thermal constant is examined in detail.