• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.102-109
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• 2014

Intra prediction in HEVC is also significantly improved from H.264/AVC with the increased prediction modes up to 35 that results in increase of the complexity cost. Hence, a fast intra mode decision algorithm is required for real-time applications. A fast intra mode decision is proposed in this paper for further complexity reduction in addition to the RMD (Rough Mode Decision) that has been adopted into the HEVC reference software, referred to as HM, for fast intra prediction. The proposed method reduces the complexity of intra mode decision by limiting the number of search modes in both steps of RMD and the final mode decision. Experimental results show that the proposed method provide about 13.2% encoding time reduction with 1.0% BD-rate increase on average over test sequences in HM 12.0.

• Journal of radiological science and technology
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• v.44 no.1
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• pp.39-46
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• 2021

This study confirmed the usefulness of the copper filter according to the mode change by comparing and analyzing the energy change according to the application of the copper filter and the change in effective dose and image quality according to the distance to the subject in the DR(Digital Radiography) system. The average energy increased when the copper filter was applied and the reduction rate by 50% of mAs was increased as the thickness of the copper filter increased according to the application of the 10 kVp rule in AEC mode. The effective dose decreased as the thickness increased when the copper filter was applied in AEC(Automatic Exposure Control) mode and manual mode according to the application of the 10 kVp rule, and the decrease rate decreased with increasing 10 kVp increments. As a result of analyzing the dicom images for AEC mode and manual mode with Image J. the PSNR(Peak Signal to Noise Ratio) values were approximate values of less than 30 dB for each mode and for each copper filter thickness. When the copper filter was applied, the average energy increased, so when the 10 kVp rule was applied, the mAs for each mode could be reduced, and the effective dose could also be reduced. However, as the distance and tube voltage increased, the reduction rate of mAs decreased, and the quality of the image was found to decrease when the copper filter was applied, but there was no difference in quality of the image when the copper filter thickness increased.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.493-498
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• 2004

The EMI noise source in a switching mode power supply is dominated by a common mode noise. If we can understand the common mode noise occurring mechanism, it is resulted to find out the method to suppress the EMI noise source in the switching mode power supply. The common mode noise is occurring mostly due to circuit is unbalanced which is caused by the capacitive coupling to frame ground, which passes through a heatsink of the switching devices. This research paper presents a new effective balancing method of buck converter circuit by mean of grounding the parasitic and compensation capacitors in correct proportion which is called that the common mode impedance balance (CMIB). The CMIB can be achieved by source, transmission line and termination balanced, such balancing, the common mode current will be cancelled out in the frame ground. The greatly reduced common mode noise can be confirmed by the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1868-1871
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• 2007

This paper proposes a novel scheme to significantly reduce mode decision time by predicting optimal mode candidates. Unlike previous fast mode decision algorithms computing RDcost in a pre-defined mode order, the proposed scheme predicts optimal mode candidates and calculates their RDcosts first, increasing the possibility to satisfy early-exit conditions sooner, resulting in fast mode decision. This H.264 mode decision time reduction enables small computing power mobile devices to handle H.264 encoding effectively. Extensive simulations show that, when compared with JM10.2, AMD and LCIMS, the proposed scheme boosts H.264 encoding speed by up to 575% with a reasonable image quality degradation.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.351-366
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• 2016

Macroperforations improve the sound absorption performance of porous materials in acoustic cavities and in waveguides. In an acoustic cavity, enhanced noise reduction is achieved using porous materials having macroperforations. Double porosity materials are obtained by filling these macroperforations with different poroelastic materials having distinct physical properties. The locations of macroperforations in porous layers can be chosen based on cavity mode shapes. In this paper, the effect of variation of macroporosity and double porosity in porous materials on noise reduction in an acoustic cavity is presented. This analysis is done keeping each perforation size constant. Macroporosity of a porous material is the fraction of area covered by macro holes over the entire porous layer. The number of macroperforations decides macroporosity value. The system under investigation is an acoustic cavity having a layer of poroelastic material rigidly attached on one side and excited by an internal point source. The overall sound pressure level (SPL) inside the cavity coupled with porous layer is calculated using mixed displacement-pressure finite element formulation based on Biot-Allard theory. A 32 node, cubic polynomial brick element is used for discretization of both the cavity and the porous layer. The overall SPL in the cavity lined with porous layer is calculated for various macroporosities ranging from 0.05 to 0.4. The results show that variation in macroporosity of the porous layer affects the overall SPL inside the cavity. This variation in macroporosity is based on the cavity mode shapes. The optimum range of macroporosities in poroelastic layer is determined from this analysis. Next, SPL is calculated considering periodic and nodal line based optimum macroporosity. The corresponding results show that locations of macroperforations based on mode shapes of the acoustic cavity yield better noise reduction compared to those based on nodal lines or periodic macroperforations in poroelastic material layer. Finally, the effectiveness of double porosity materials in terms of overall sound pressure level, compared to equivolume double layer poroelastic materials is investigated; for this the double porosity material is obtained by filling the macroperforations based on mode shapes of the acoustic cavity.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.399-406
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• 2019

This study aims to find geometric parameters that the radiologist can change from time to time to reduce dose in angiography examinations. Depending on the geometric characteristics, the values calculated by effective dose were compared, while filming in fluoroscopy mode and Digital subtraction angiography, respectively. The study found that the lower the dose was in FPS mode, the lower the dose was reduced to 30-40%. Doses according to the X-ray angle were measured highest in AP View and lower as the angle went in the head direction. The greater the FOV, the higher the dose was 1.2-1.6 times, and the closer the distance between the X-ray tube and the table, the greater the dose was about 10%. Source-image intensifier distance (SID) get longer to 100 mm, dose of each fluoroscopy and Digital subtraction angiography increase up to 25-30%. In conclusion, various geometric characteristics in angiography examinations are parameters that can be applied by radiographers as frequently as possible, and appropriate geometric properties can be considered and applied in various situations, resulting in appropriate dose reduction.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.49-65
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• 2023

In response to the growing global concern for the environment, the international community has recently committed to achieving 'carbon neutrality.' As a result, numerous studies have been conducted on mode choice models that include carbon emissions as a variable. However, few studies have established a correlation between individual preferences and carbon emissions. In this study, a new mode of transportation named sustainable public transit (SPT), incorporating carbon-reducing transport options like electric scooters, is proposed. Analyzing the individual preferences of commuters on carbon emissions through factor analysis, a stated preference (SP) survey was conducted. A mode choice model for SPT was constructed using multinomial logit models. The results of the analysis showed that gender, income, and specific preferences, such as a passion for exploring new routes, a preference for intermodal transfers, knowledge of carbon reduction, and carbon reduction practices, significantly influence latent preferences for SPT. Therefore, this study is significant as it considers carbon emissions as an attribute variable during the construction of mode choice models and reflects the individual preference variables associated with carbon reduction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.216-221
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• 2002

In this paper, the transmitted noise reduction of smart panels of which passive piezoelectric shunt damping is used, is experimentally studied. Shunt damping experiments are based on the measured electrical impedance model. A passive shunt circuit composed of inductors, and a load resistor is devised to dissipate the maximum energy into the joule heat energy. For multi-mode shunt damping, the shunt circuit is redesigned by adding a blocking circuit. Also the optimal location of the piezoelectric patch is studied by FEM in order to cause the maximum admittance from the patch for each mode of aluminum plate. In results, the transmitted sound pressure level of panels is efficiently reduced for multi-modes

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.769-773
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• 2004

Conventional SVPWM method has null switching vectors. Null switching vectors cause high common-mode voltage in induction motor drive system. The newly developed common mode voltage reduction PWM technique don't use zero switching state for inverter control. It is realized by changing software without additional hardware. Simulation and experimental results show that proposed method are reduced common mode voltage more than conventional method.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.384-388
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• 2004

High frequency common mode voltage produced by power inverters are a major cause of conducted EMI, creating motor ground currents, bearing currents and other harmful by products. This paper focuses on a new SVPWM method with random PWM injection to reduce conducted EMI noise. A New PWM technique associated with the common mode voltage can be significantly reducing and contributes to mitigate. The common mode voltage to $50\%$ in comparison with that for conventional SVPWM technique. Validation of the theory and reduction methods are then performed experiment ally based on an induction motor drive.