• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.277-283
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• 2020

In a concentric magnetic gear, which replaces the teeth of a mechanical gear with a permanent magnet, the polar ratio of the magnet that determines the reduction ratio affects the behavior of the magnetic gear dramatically. This study analyzed the density of transmission torque, the efficiency of torque considering the solid loss, and the torque quality, including the cogging characteristics using finite element analysis. When the pole number on the driving side was changed from two to five, it was confirmed that there was an optimal pole ratio, in which the transmission torque was maximized. Because eddy current generation density is proportional to the magnetic field, the transmission efficiency also shows a similar tendency to the transmission torque density, and the efficiency is more than 95% at a low gear ratio. The cogging characteristics due to the interaction of the permanent magnets with the limited number of poles are inversely proportional to the least common multiple between the number of magnets on the drive side and the number of modulator teeth. A test model was built for the transmission torque evaluation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.884-892
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• 2006

A friction-type reinforcing member(FRM) is proposed for the purpose of upgrading wind resistant performance of a transmission tower and verified through cyclic loading tests. First, suitable install scheme of the FRM is investigated through numerical analysis. Main-post-reinforcing type and X-brace type installation schemes are examined, and numerical analysis shows that the former is more effective due to the vertical cantilever type behavior of the transmission tower. Based on this result, two types of the FRM's, dissipating energy in slotted belted connections, are proposed. The one utilizes the relative displacement between the FRM and the main post, and the other utilizes that between the separated angles consisting of the FRM as a slip deformation of the slotted bolted connection. Proposed FRM's are installed on each main post of the 1/2 scale substructure models of an actual transmission tower body. From cyclic loading tests, the latter type of the proposed FRM's dissipates energy more effectively and its slip load is controlled by applied torque well, and shares considerable amount of the axial force in the main post.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.632-640
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• 2007

The low force estimation method of skeletal muscle was proposed by using ICA(independent component analysis) and neuro-transmission model. An EMG decomposition is the procedure by which the signal is classified into its constituent MUAP(motor unit action potential). The force index of electromyography was due to the generation of MUAP. To estimate low force, current analysis technique, such as RMS(root mean square) and MAV(mean absolute value), have not been shown to provide direct measures of the number and timing of motoneurons firing or their firing frequencies, but are used due to lack of other options. In this paper, the method based on ICA and chemical signal transmission mechanism from neuron to muscle was proposed. The force generation model consists of two linear, first-order low pass filters separated by a static non-linearity. The model takes a modulated IPI(inter pulse interval) as input and produces isometric force as output. Both the step and random train were applied to the neuro-transmission model. As a results, the ICA has shown remarkable enhancement by finding a hidden MAUP from the original superimposed EMG signal and estimating accurate IPI. And the proposed estimation technique shows good agreements with the low force measured comparing with RMS and MAV method to the input patterns.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.435-443
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• 2010

The current design practice of an electric transmission tower is based on the allowable stress design. Design strengths of the electric transmission tower's compression member are determined by buckling the strength of the member itself without considering joint strength. There is a possibility of a joint failure prior to the buckling of a member. Therefore, in this study, joint strength is calculated for various member forces, and the shape of joint and database of strength were established. These data was compared with the member strength obtained from previous research studies based on an equivalent nonlinear analysis technique. Finally, practical evaluation and design method to distinguish failure mode in an electric transmission tower member is proposed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.202-211
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• 2001

This paper deals with an analysis of multipath which affect a transmission performance in underwater acoustic channel. Underwater acoustic channel with multipath structure is introduced to mathematical modelling for a basin environment. In this paper, SMR(Signal to Multipath Ratio) which is defined as a parameter of multipath's effect is presented as a mathematical equation, and the equation of SMR is simulated by MATLAB program. Furthermore, this paper is also dealt with an implementation of modulation and demodulation system for acoustic transmission. Acoustic Transmission is limited by frequency bandwidth, so $\pi/4 QPSK$(Quadrature Phase Shift Keying) methods which is very useful at frequency ]imitation and FM(Frequency Modulation) are used at acoustic communication system. This implemented hybrid modulation/demodulation system is used as an analog board of image transmission system. In this system, adaptive equalization for reducing the multipath effect and baseline JPEG used for an image compressing are also stated.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.122-129
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• 2001

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite- Difference Time-Domain(FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency- dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.304-310
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• 2014

This paper presents the analysis of the coupling coefficient(k), Q value of the resonator, and the optimum loaded resistance at Rx for the magnetically coupled wireless power transmission using two loops(resonators). In addition, the metamaterial, conductor, and the relay methods have been used in order to improve the limitation problem of transmission efficiency by using the figure of merit. We have achieved the increase of transmission efficiency about 11~60 % using the proposed methods by analyzing and comparing the results based on EM simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.419-425
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• 2000

This paper deals with an analysis of multipath which affect a transmission performance in underwater acoustic channel. Underwater acoustic channel with multipath structure is introduced to mathematical modelling for a basin environment. In this paper, SMR(Signal to Multipath Ratio) which is defined as a parameter of multipath's effect is presented as a mathematical equation, and the equation of SMR is simulated by MATLAB program. Furthermore, this paper is also dealt with an implementation of modulation and demodulation system for acoustic transmission Acoustic Transmission is limited by frequency bandwidth so $\pi$/4 Quadrature Phase Shift Keying) methods which is very useful at frequency limitation and FM(Frequency Modulation) are used at acoustic communication system. This implemented hybrid modulation/demodulation system is used as an analog board of image transmission system

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.112-119
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• 2009

An automatic transmission of construction equipment is controlled by hydraulic and electronic system for doing in various functions like as shifting and operation. The shifting is operated by the engaged and disengaged clutch motion from hydraulic power. On the shifting process, suitable pressure control to the clutch is required for smooth shifting. Hydraulic control system in the automatic transmission is divided by the pilot control type and the direct control type greatly. The direct control type has an advantage than the pilot control type. Because the structure is simple, the design and the manufacture are having less troubles and the system can be maximized precision pressure control. However, the excellent performance proportional control valve should be used to achieve proper control-ability. In this study, the dynamic analysis model composing the automatic transmission and hydraulic system for forklift truck is presented to simulate the characteristics of hydraulic system about the direct control type. That model is verified the validity compared the results of the testing examination. Parameters of input signal are analyzed to reduce the output torque according to input control signal is affected in shifting characteristic.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1673-1678
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• 2015

This paper describes magnetic field on power cable in underground transmission systems. Based on specification which is being used in domestic power utility, magnetic field was analyzed in accordance with line arrangement, line burial depth and phase spacing. Magnetic field magnitude and its trend were understood in each circuit type such as double circuits, triple circuits and quadruple circuits of underground transmission systems. In addition, magnetic field was analyzed according to phase arrangement changing in each circuit. Finally, the proper phase arrangement configuration type was suggested by the evaluation of analysis result. Magnetic field was calculated by using Biot-Savart's law. According to the evaluated magnetic fields based on phase layout configuration in each circuit, it figured out that each of magnetic fields was different. As a result, this paper proposes a proper phase layout configuration for generating minimum magnetic field. It is evaluated that the phase layout configuration in each circuit proposed in this paper can be used at actual underground transmission systems.