• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.3
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• pp.88-96
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• 2007

H.264 is a new international video coding standard that can achieve considerably higher coding efficiency than conventional standards. Its coding gain has been achieved by employing advanced video coding methods. Specially, the increased number of macroblock modes and the complex mode decision procedure using the Lagrangian optimization are the main factors for increasing coding efficiency. Although H.264 obtains improved coding efficiency, it is difficult to do an real-time encoding because it considers all coding parameters in the mode decision procedure. In this paper, we propose a fast mode decision algorithm which classifies the macroblock modes in order to determine the optimal mode having low complexity quickly. Simulation results show that the proposed algorithm can reduce the encoding time by 34.95% on average without significant PSNR degradation or bit-rate increment. In addition, in order to show the validity of simulation results, we set up a low boundary condition for coding efficiency and complexity and show that the proposed algorithm satisfies the low boundary condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.380-386
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• 2014

In this paper, a higher-order mode coupler using coaxial-structure waveguide for Ku-band monopulse satellite tracking is proposed. The proposed higher-order mode coupler is built in a coaxial structure for compactness and weight reduction, making it suitable for mobile tracking systems. The inner circular waveguide of coaxial-structure is used to extract the fundamental mode signal and the high-order mode signal is extracted from the four slots of the outer circular waveguide and then transmitted via given stepped rectangular waveguide structure. The simulated results show that proposed higher-order mode coupler covers 250 MHz(12.75 GHz ~ 13.00 GHz) bandwidth with return loss and insertion loss characteristics. The antenna patterns of fundamental mode and higher-order mode applicable to monopulse tracking are generated successfully. Designed higher-order mode coupler using coaxial waveguide structure for Ku-band is expected to be used for high precision monopulse satellite tracking systems.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.4
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• pp.69-76
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• 2005

In this paper, a 2 stage 6-pole bandpass filter(BPF) is designed and implemented by using triple-mode cavity for satellite payload system. The BPF has a 100MHz bandwidth at the center frequency of 14.5GHz(Ku-band) and the response of the filter is the Chebyshev function. The cavity filter uses two orthogonal $TM_{113}$ modes and one $TM_{012}$ mode. The coupling between the adjacent cavityes(intercavity coupling) results in a Chebyshev response and is accomplished by only H-filed component of If modes. The size and location of intercavity slot is determined by the coupling equation from E-and H-field of TE and TM resonant modes in circular cavity. The 2-stage 6-pole triple-mode cavity BPF has the insertion loss of 2.4dB and the reflection loss of 15dB in the passband. The triple-mode BPF proposed in this thesis can be used as channel filters for satellite payload system and can minimize filter assembly in general wireless communication system.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.201-206
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• 2012

The indirect-contact ECG measurement is a newly developed method for unconstrained and nonconscious measurement in daily life. This study introduced a new method of electrode circuit design developed for reducing the 60Hz power line noise observed at the indirect-contact ECG measurement. By the introduced common-mode-driven shielding, the voltage of the electrical shield surrounding the capacitive coupling electrode is maintained at the same as the common mode voltage. Though the method cannot reduce the level of common mode voltage itself, that reduces effectively the differential mode noise converted from the common mode voltage by the difference of cloth impedance between the two capacitive coupling electrode. The experiment results using the actual indirect-contact ECG showed that the 60Hz power line noise was reduced remarkably though the reduction ratio was smaller than the expected by the theory. Especially, the reduction ratio became large for the large difference of cloth. It is expected that the introduced method is useful for reducing the power line noise under condition of poor electrical grounding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1068-1076
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• 1996

In this paper, a new continuous-time current-mode integrator as basic building block of the low-voltage analyog current-mode active filters is proposed. Compared to the current-mode integrator which is proposed by Zele, the proposed current-mode integrator had higher unity gain frequency and output impedance in addition to lower power dissipation. And also, a current-mode third-order lowpass active filter is designed with the proposed current-mode integrator. The designed circuits are fabricated using the ORBIT's $1.2{\mu}{\textrm{m}}$ deouble-poly double-metal CMOS n-well process. The experimental results show that the filter has -3dB cutoff frequency at 44.5MHz and 3mW power dissipation with single 3.3V power supply and also $0.12mm^{2}$ chip area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.1
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• pp.69-76
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• 2017

In this study, design of a small hybrid rocket is carried out using Failure Mode and Effects Analysis (FMEA) and Criticality Analysis(CA), which is a method for qualitative and semi-quantitative reliability analysis. In order to carry out FMEA, the structure of the hybrid rocket is divided into 31 parts and 72 potential failure modes. As a result of the FMEA, the relationship between potential failure modes, causes and effects, and their severity are evaluated qualitatively. Criticality analysis is followed for the failure modes, in which the criticality number is estimated using the failure rate information available from the handbook. Moreover, the failure modes with higher criticality and severity are chosen for improvement, and a series of design or material changes are made for the improvement of the hybrid rocket reliability.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.34-40
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• 2012

In this study, effects of bonding agent, e.g. epoxy, on the behavior of fundamental guided wave modes propagated in FRP plate bonded on a concrete, are investigated. Global matrix model of multilayered FRP-epoxy-concrete system was constructed to obtain the velocity and attenuation dispersion curves of the fundamental A0 and S0 modes. Two variables, thickness and elastic modulus of epoxy layer, were considered in the dispersion analysis. It was found that both the thickness and the elastic modulus of epoxy layer greatly affect the phase velocity and attenuation of S0 mode while those are negligible for A0 mode. Based on the results, it was concluded that S0 mode is more effective than A0 mode for bonding condition assessment for FRP plate bonded concrete.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.506-511
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• 2006

This paper considers a method to design sliding mode observers for a class of uncertain systems using Linear Matrix Inequalities(LMI). In an LMI-based sliding mode observer design method for a class of uncertain systems the switching surface is set to be the difference between the observer and system output. In terms of LMIs, a necessary and sufficient condition is derived for the existence of a sliding-mode observer guaranteeing a stable sliding motion on the switching surface. The gain matrices of the sliding-mode observer are characterized using the solution of the LMI existence condition. The results are illustrated by an example.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.386-394
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• 1997

In this study, a few of the modeling methods for flexible spacecraft were introduced and adopted to the modeling of a 3-axes stabilization satellite. The generated model was put into pre-built rigid body attitude control loop. A Lumped Parameter Model(Global Mode Model: GMM) was recommended for the absence of the Finite Element Method(FEM) model. Finally, GMM was compared with FEM in terms of designing a control filter. A 1st-order filter was designed to meet requirements of the controller since the new flexible model was applied, and that filter was added to motor controller and axis controller. MATLAB/Simulink was used as a tool for design and simulation of the control loop and filter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.998-1003
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• 2006

In this research, engine performance and emission characteristics of a 12,000cc heavy duty diesel engine was investigated by the application of GTL and ULSD fuels. The test was conducted at several engine speeds and loads under a single mode and a ESC mode. GTL fuel proves that it can be applicable to vehicles without engine modification.