• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1607-1609
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• 2005

This paper presents capability calculation methods for regenerative inverter in DC electrified transit system. The proposed method uses a train performance and power simulation tool to calculate the regenerative power generated in the DC substation and decide the capability of regenerative inverter. The capability of regenerative inverters for Seoul subway line 5, 6, 7, and 8 has been calculated.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.4
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• pp.1-9
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• 2008

In this paper, an energy regeneration algorithm is proposed to make the maximum use of the regenerative braking energy for a parallel hybrid electric vehicle(HEV) equipped with a continuous variable transmission(CVT). The regenerative algorithm is developed by considering the battery state of charge(SOC), vehicle velocity and motor capacity. The hydraulic module consists of a reducing valve and a power unit to supply the front wheel brake pressure according to the control algorithm. In order to evaluate the performance of the regenerative braking algorithm and the hydraulic module, a hardware-in-the-loop simulation (HILS) is performed. In the HILS system, the brake system consists of four wheel brakes and the hydraulic module. Dynamic characteristics of the HEV are simulated using an HEV simulator. In the HEV simulator, each element of the HEV powertrain such as internal combustion engine, motor, battery and CVT is modelled using MATLAB/$Simulink^{(R)}$. In the HILS, a driver operates the brake pedal with his or her foot while the vehicle speed is displayed on the monitor in real time. It is found from the HILS that the regenerative braking algorithm and the hydraulic module suggested in this paper provide a satisfactory braking performance in tracking the driving schedule and maintaining the battery state of charge.

• BMB Reports
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• v.55 no.2
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• pp.65-71
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• 2022

Regenerative medicine is a research field that develops methods to restore damaged cell or tissue function by regeneration, repair or replacement. Stem cells are the raw material of the body that is ultimately used from the point of view of regenerative medicine, and stem cell therapy uses cells themselves or their derivatives to promote responses to diseases and dysfunctions, the ultimate goal of regenerative medicine. Stem cell-derived extracellular vesicles (EVs) are recognized as an attractive source because they can enrich exogenous microRNAs (miRNAs) by targeting pathological recipient cells for disease therapy and can overcome the obstacles faced by current cell therapy agents. However, there are some limitations that need to be addressed before using miRNA-enriched EVs derived from stem cells for multiplexed therapeutic targeting in many diseases. Here, we review various roles on miRNA-based stem cell EVs that can induce effective and stable functional improvement of stem cell-derived EVs. In addition, we introduce and review the implications of several miRNA-enriched EV therapies improved by multiplexed targeting in diseases involving the circulatory system and nervous system. This systemic review may offer potential roles for stem cell-derived therapeutics with multiplexed targeting.

• The KSFM Journal of Fluid Machinery
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• v.17 no.1
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• pp.35-40
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• 2014

A multi-objective optimization of a regenerative fan for enhancing the aerodynamic and aeroacoustic performance was carried out using an integrated fan design system, namely, Total FAN-Regen$^{(R)}$. The Total FAN-Regen$^{(R)}$ was developed for non-specialists to carry out a series of design process, viz., computational preliminary design, three-dimensional aerodynamic and aeroacoustic analyses, and design optimization, for a regenerative fan. An aerodynamic analysis of the regenerative fan was conducted by solving three-dimensional Reynolds-averaged Navier-Stokes equations using the shear stress transport turbulence model. And, an aeroacoustic analysis of the regenerative fan was implemented in a finite/infinite element method by solving the variational formulation of Lighthill's analogy based on the results of the unsteady flow analysis. An optimum shape obtained by Total FAN-Regen$^{(R)}$ shows the enhanced efficiency and decreased sound pressure level as much as 1.5 % and 20.0 dB, respectively, compared to those of the reference design. The performance test was carried out for an optimized regenerative fan to validate the performance of the numerically predicted optimal design.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.53-61
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• 2006

Axisymmetric numerical thermal analysis for a 3-dimensional regenerative cooling system in a rocket engine is carried out. To predict the accurate heat transfer with the stiff temperature distribution, several tests have been conducted for the grid size, the properties variation of the coolant and the combustion gas depending on temperature. The axisymmetric heat flux model is defined using fin efficiencies and is designed to be equivalent to the heat flux of the 3-dimensional coolant channel. For comparison purpose, the 1-dimensional analysis using Bartz equation is also conducted. The performance of the present model in predicting the cooling characteristics of a 3-dimensional regenerative cooling system is compared with the 3-dimensional results of RTE(Rocket Thermal Evaluation). It is found that the present method predicts much closer results to those of RTE code than 1-dimensional analysis.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.443-448
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• 2005

This paper proposed a regeneration inverter system, which can regenerate the excessive power form dc bus line to ac source for traction system. The proposed regeneration inverter system for dc traction can reduce harmonics which are include to ac current source. The regenerative inverter is operated as two modes. As a regeneration inverter mode, it can recycle regenerative energy caused by decelerating tractions and as an active power filter mode, it can compensate for harmonic distortion produced by the rectifier substation. In the paper, a regeneration inverter used PWM DC/AC converter algorithm. And an active power filter used p-q theory. The simulation was composed as a prototype model[3kW]. Simulation results show that two algorithm can be used to real model[100kW]. Finally, the inverter was successfully operated as regeneration mode.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1473-1478
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• 2007

In the respect of energy saving and reusing, it is necessary to reduce greenhouse gases emission and to enhance the operation efficiency in electric railway system. Recently, as the power electronics technologies are advanced, some countries have focused on the regenerative inverter to use regeneration energy on each line. When the electric tractions are stopped or slowed down, it is useful to supply the surplus energy to the power source by regenerative system, which increases its energy efficiency. Also, the generated energy can be supply to other tractions or equipments inside traction. Thus, it may help reduce construction cost of additional power plants. The purpose of this study is to describe the development status of the regenerative inverter system which suppress extra DC-line voltage and regenerate the energy instead of using a resister.

• Journal of Communications and Networks
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• v.12 no.1
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• pp.11-18
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• 2010

Diversity-multiplexing tradeoff (DMT) is an efficient tool to measure the performance of multiple-input and multiple-output (MIMO) systems and cooperative systems. Recently, cooperative multicast system with wireless network coding stretched tremendous interesting due to that it can drastically enhance the throughput of the wireless networks. It is desirable to apply DMT to the performance analysis on the multicast system with wireless network coding. In this paper, DMT is performed at the three proposed wireless network coding protocols, i.e., non-regenerative network coding (NRNC), regenerative complex field network coding (RCNC) and regenerative Galois field network coding (RGNC). The DMT analysis shows that under the same system performance, i.e., the same diversity gain, all the three network coding protocols outperform the traditional transmission scheme without network coding in terms of multiplexing gain. Our DMT analysis also exhibits the trends of the three network coding protocols' performance when multiplexing gain is changing from the lower region to the higher region. Monte-Carlo simulations verify the prediction of DMT.

• Journal of Aerospace System Engineering
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• v.14 no.4
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• pp.32-39
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• 2020

A technological review and analysis were performed on thermal cracking of aviation hydrocarbon fuels that circulate as coolants in regenerative cooling systems of hypersonic flights. Liquid hydrocarbons decompose into low-carbon-number hydrocarbons when they absorb a considerable amount of energy at extremely high temperatures, and these thermal cracking behaviors are represented by heat sink capacity, conversion ratio, reaction products, and coking propensity. These parameters are closely interrelated, and thus, they must be considered for optimum performance in terms of the overall heat absorption in the regenerative cooling system and supersonic combustion in the scramjet engine.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.141-148
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• 2009

Afterfogging of the regenerative gas turbine system has an advantage over inlet fogging in that the high outlet temperature of air compressor makes the injection of more water and the recuperation of more exhaust heat possible. This study investigates the effects of turbine inlet temperature (TIT) on the performance of regenerative gas turbine system with afterfogging through a thermodynamic analysis model. For the standard ambient conditions and the water injection ratios up to 5%, the variation of system performance including the thermal efficiency is numerically analyzed with respect to the variations of TIT and pressure ratio. It is also analyzed how the maximum thermal efficiency, net specific work, and pressure ratio itself change with TIT at the peak points of thermal efficiency curve. All of these are found to increase almost linearly with the increases of both TIT and water injection ratio.