• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.843-850
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• 2002

This paper presents a simulation method using the transmission line modeling to reduce simulation runtime of hydraulic control systems. This method is based on separating the system components each other using the transmission line elements prior to simulation, which leads to divide the simulated system into several subsystems suitable for an even more efficient integration. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. By applying variable integration timestep to parallel hydraulic circuits via parallel processing, it is shown that simulation run-time can be reduced significantly compared with that of Runge Kutta method.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.682-687
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• 2000

In this paper, the simulation methods using transmission lines are studied and realized, which are necessary in design and analysis of hydraulic control systems. The basic idea of this method is that system components are separated by transmission line element for simulation. The PI-controller can keep inductance level as low as desired. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. Parallel hydraulic circuits are simulated using parallel processing algorithm. To shoe that using variable timestep size in each subsystem, simulation time can be reduced. Performance of the simulation results is compared with that of Runge Kutta method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.703-707
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• 2007

The line pressure control system for an automotive transmission in which a bleed type variable force solenoid(VFS) is applied, has been constructed and experimentally investigated. The hydraulic circuit of the system includes a line pressure control valve, a reducing valve, an accumulator, various orifices and a VFS. Static and dynamic responses of the throttle and line pressure have been monitored and discussed for various test conditions.

• ETRI Journal
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• v.31 no.1
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• pp.42-50
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• 2009

A new method for simulating voltage and current distributions in transmission lines is described. It gives the time domain solution of the terminal voltage and current as well as their line distributions. This is achieved by treating voltage and current distributions as distributed state variables (DSVs) and turning the transmission line equation into an ordinary differential equation. Thus the transmission line is treated like other lumped dynamic components, such as capacitors. Using backward differentiation formulae for time discretization, the DSV transmission line component is converted to a simple time domain companion model, from which its local truncation error can be derived. As the voltage and current distributions get more complicated with time, a new piecewise exponential with controllable accuracy is invented. A segmentation algorithm is also devised so that the line is dynamically bisected to guarantee that the total piecewise exponential error is a small fraction of the local truncation error. Using this approach, the user can see the line voltage and current at any point and time freely without explicitly segmenting the line before starting the simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2339-2344
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• 2014

of a microstrip transmission line, this transmission line can operate as the microstrip line or the coplanar line according to open or short connection between the ungrounded copper plane and grounded plane on the base plane. Two different type operation of the transmission line means that one transmission line can have two different characteristic impedances. This paper proposes and fabricates the circuit to be operated 2-ports power transmission line or 2-way power divider with the stable input matching characteristic by using this dual-impedance transmission line. The proposed circuit operates 2-ports power transmission line in case of the coplanar line or 2-way power divider line in case of the microstrip line. The fabricated circuit shows $S_{21}$ > -0.2 dB and $S_{11}$ < -15 dB above 700 MHz when the circuit operates 2-ports power transmission line. And, it is $S_{21}$ > -3.8 dB, $S_{11}$ < -10 dB and $S_{21}/S_{31}$ < ${\pm}0.3dB$ above 700 MHz when the circuit operates 2-way power divider.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.1
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• pp.35-40
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• 2005

In this paper, we designed and fabricated the variable impedance line by using the DGS(Defected Ground Structure) which is useful in mounting the external lumped elements. Also we used a varactor diode as Control device stuff at the proposed variable impedance line. We are able to change the impedance of transmission line as varied the capacitance of varactor diode by adjusting DC bias. The impedance variation of the proposed DGS line is about maximum 70 Ω. We will study about the application of DAM(Direct antenna modulation) in the future work.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.6
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• pp.921-928
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• 1990

A multivariable equalizer is designed which compensates transmission distortion for coaxial transmission line. The characteristic transfer function with bilateral parameter domain is approximated using the expansion method of orthonormal function and Gram Schmidt orthogonal function, but the parameter domain of approximated function is limited to unilateral. To solve that problem, Bode type transfer function is used to give bilateral variable characteristic to approximated function. The multivariable equalizer in this paper can be substituted for the current equalizer which consist of a fixed equalizer and a variable equalizer.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.3
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• pp.387-393
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• 1987

The introduction of a digiral subscriber loop transmission system necessitates an optimized line interface solution. To meet this objective an adaptive line equalizer has been developed. The equalizer can be compensated up to 42 dB line loss at 200KHz, and operated up to 3.2 Km transmission length (0.4 mm\ulcornercable)at a rate of 400Kb/s. This has been builted using a variable \ulcorner equalizer to compensate a frequency-attenuation characteristics of metallic cable, an AGC (automatic gain control) circuits with simple control algorithm, and various filters to minimize a transmission constraints over subscriber loop. The purpose of this paper is to present a short description of a design of the adaptive line equalizer with a summary of implementation results. Some design concepts and considerations which results in an implementation of the equalizer are also given.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.41-46
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• 2012

Visible light communication(VLC) system based on LED devices has some specific advantages compared with RF system. First, visible light is harmless to human and there is no limit to using frequency band. Also, VLC system has good security performance, and it can use the very wide frequency band for data transmission. However, for simultaneously using the illumination and data transmission in VLC systems, degradation of code rate is occurred. So, in this paper, we proposed the novel line coding scheme for flicker free and efficient dimming control in VLC systems. From the simulation results, it is confirmed that proposed scheme has good flicker, dimming, and transmission performance compared to conventional variable pulse position modulation(VPPM) scheme.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.81-91
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• 2000

Dynamic models of line regulator valve(LRV) and ratio control valve (RCV) are obtained for an electronic controlled CVT. LRV and RCV are operated by variable force solenoid(VFS). Considering the CVT shift dynamics, oil pump's efficiency and saturation characteristics of VFS, simulations are performed and compared with test results. Simulation results are in good agreement with the experiments, which shows the validity of the dynamic models of LRV and RCV obtained. In addition, the effects of the orifice size in the exhaust port of RCV are investigated. Simulation results show that as the orifice size decreases, the residual pressure in the primary actuator increases which insures the large torque transmission capacity, meanwhile the duration time for the downshift increases.