• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.84-89
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• 1998

BTA drilling among the deep hole drilling is using for the improvement of productivity and the high-efficient working. As the deep hole drilling with BTA drill is satisfied with the required quality by one-pass processing, more deeper hole depth, the accuracy of materials is affected by bending vibration and cutting speed. This paper is studied that the shapes of material (surface roughness, roundness) is affected by cutting condition compared actual roundness with lobe shape with modeling of computer through the experiments in the BTA drilling system with BTA drill.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.3
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• pp.467-476
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• 2010

Purpose : This study was performed to understand the relationship between hand and mouth shapes using functional magnetic resonance imaging(fMRI). Methods : Two healthy volunteers without any previous history of physical or neurological illness were recruited. fMRI was done that volunteers was 6 repeated of natural mouth, close mouth and open mouth while power grip and pinch grip movement. Results : Cerebral cortex activation was not well observed for the natural mouth during the power grip exercise. For the closed mouth, the temporal lobe, Broca's area, the prefrontal area related to thinking and judgment, the supplementary motor area, the auditory area and Wernicke's area were activated. For the open mouth, cortical activation was also observed in the temporal lobe, Wernicke's area, the prefrontal area related to thinking and the orbital frontal area related to visual sense. During the pinch grip exercise, cortical activation was observed for the natural mouth in the primary sensory area, Wernicke's area, the primary and supplementary motor area, and the prefrontal area. For the closed mouth, cortical activation was observed in the temporal lobe, Wernicke's area, the prefrontal area related to thinking, the secondary visual area, the primary sensory area and the supplementary motor area. In the case of the open mouth, cortical activation was observed in a few parts in the temporal lobe as well as Wernicke's area, the prefrontal area related to thinking, and other areas related to visual sense such as the primary visual area, the secondary visual area and the visual association area. Conclusion : Brain was more activation for close mouth and open mouth more than natural mouth movement.

• The KSFM Journal of Fluid Machinery
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• v.16 no.1
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• pp.5-10
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• 2013

The performance of screw air compressor is affected by rotor profile, lobe number, air end wrap angle, rotor L/D ratio, suction and discharge ports, revolutions of air end and load regulation control, etc. In general, an efficient screw compressor needs a rotor profile of which has a large flow cross-section area, short sealing lines and a small blow-hole. In this study, experimental study was performed with newly designed $5{\times}6$ rotor profile and various shapes of air end. Results show that the measured specific power consumption of the newly designed screw compressor appeared to be lower than any other published data for the equivalent screw compressors manufactured.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.124-131
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• 2006

A gerotor pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. Especially the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of internal lobe pump whose the main components are the rotors: usually the outer one is characterized by lobes with circular shape, while the inner rotor profile is determined as conjugate to the other. For this reason the first topic presented here is the definition of the geometry of the rotors starting from the design parameters. The choice of these parameters is subject to some limitations in odor to limit the pressure angle between the rotors. Now we will consider the design optimization. The first step is the determination of the instantaneous flow rate as a function of the design parameter. This allows us to calculate three performance indexes commonly used far the study of positive displacement pumps: the flow rate irregularity, the specific flow rate, and the specific slipping. These indexes are used to optimize the design of the pump and to obtain the sets of optimum design parameter. Results obtained from the analysis enable the designer and manufacturer of oil pump to be more efficient in this field, and the system could serve as a valuable one for experts and as a dependable training aid for beginners.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.39-44
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• 2007

In this paper, satellite searching and tracking method for the satellite antenna in naval vessels system are proposed. For fast searching satellite, Wide Range Search(WRS) algorithm is proposed where the signal strength of side-lobe is utilized as well as that of main-lobe. Satellite tracking algorithm to stabilize satellite antenna is based on conical-scanning which is accomplished by the use of the sub-reflector located in front of the focus of the reflector. The sub-reflector rotates about a slightly tilted axis by means of a motor and shapes the antenna beam to utilize stabilization. To show the validity of the proposed method, an experimental example is represented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.414-423
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• 2015

Array error analysis and correction of active array antenna are described in this paper. Array elements composed of radiator and TR(Transmit & Recive) module have error(magnitude and phase difference among array elements) which affects SLL(Side Lobe Level). Error affectedness level depends on ideal SLL according to antenna aperture weighting, number of array elements and antenna effective aperture. To satisfy required SLL, correction of array elements is necessary; adopted differently per errors, and weighted differently per shapes of antenna and required SLL. Errors of every individual element had been defined, performance of the antenna with or without error correction had been estimated and proved through near field test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1610-1624
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• 1998

An axisymmetric jet is forced with two helical fundamental waves of identical frequency spinning in opposite directions and an additional axisymmetric sub harmonic wave. The subharmonic component rapidly grows downstream from subharmonic resonance with the fundamental, significantly depending on the initial phase difference. The variations of the subharmonic amplitude with the initial phase difference show cusp-like shapes. The amplification of the sub harmonic results in 'vortex pairing of helical modes'. Furthermore, azimuthal variation of the amplification induces an asymmetric jet cross-section. When the initial subharmonics is imposed with an initial phase difference close to a critical value, the jet-cross section evolves into a three-lobed shape. One lobe is generated by the enhanced vortex pairing and the other two lobes are generated by the delayed vortex pairing. Thus, it is confirmed that the initial phase difference between the fundamental and the subharmonic plays an important role in controlling the jet cross-section.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.1-11
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• 1999

An immunohisochemical study on the cerebral ganglion of the African giant snail, Achatina fulica. was conducted by applying the AB/AY staining and the avidin-bovine-peroxidase complex staining methods. The followings are the results obtained throughout the study. The cerebral ganglion of Achatina fulica is an ellipsoidal body of 2 x 1 mm in size, which is connected by the cerebral commissure of 1 mm in diameter. The cross-section through the cerebral ganglion, shaped like a butterfly, is divided into the medio-dorsal parts, the latero-dorsal parts, the caudo-dorsal parts, and the lateral lobes. In the medio-dorsal and latero-dorsal parts, the LG cells and the DG cells are found mixed, although the LG cells are dominant. In lateral lobe, however, the Y cells are quite dominant, while the LG cells and the DG cells are seldom found. The LG cells are 20-70 $\mu\textrm{m}$ in sizes and circular or ellipsoidal in shapes. They are stained light green with the AB/AY. 1 - 3 nucleoli are found in karyolymph, where granular chromantins are evenly distributed. In cytoplasm, it is found that the secretory granules are evenly developed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.177-184
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• 2018

In this paper, we analyze the characteristics of the antenna by changing the structure of the radiator and the angle of the branch of the array patch antenna. First, the structure of the radiator was changed from the rectangular patch to a hexagonal patch, a triangular patch. Secondly, we changed the angle of the feeder branch to $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$. When the branch angle is $10^{\circ}$, the measured 10dB frequency band is 23.38 GHz-24.19GHz and the bandwidth is 810MHz. The fabricated antenna has a gain of 9.65-10.06dBi at 24.05 GHz. The beam width of the main lobe is $12^{\circ}$, and the antenna size is $70{\times}36mm^2$. In addition to the rectangular patch, it is possible to maintain the performance by using patches of other shapes, and it is confirmed that by changing the feeder branch at various angles, it is possible to reduce the substrate size and contribute to diversity in the fabrication of the array antenna.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.329-335
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• 2014

This study aimed to understand the internal flow characteristics of a liquid droplet subject to periodic forced vibration. In order to predict the resonance frequency of a droplet, a high-speed camera and macro lens were used to capture internal flow characteristics of a droplet placed on a vibrating hydrophobic surface. Results showed that the droplet assumed a variety of shapes depending on the resonance mode of free droplet, particularly in modes 2, 4, 6, and 8. In addition, the induced internal vortex flow inside the droplet was also observed in each mode. Typically, the induced flow moved upwards along the axis of symmetry and downwards along the surface of the droplet, that is, from the apex to the contact line in modes 2 and 4, after which it broke into a smaller vortex. On the other hand, the large-scale vortex always remained steady in modes 6 and 8. The speed of the flow in mode 4 was always greater than that in mode 2, but those in modes 6 and 8 were similar.