• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.23-27
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• 2006

The power split hybrid powertrain is considered to be one of the most prospective configuration for the hybrid electric vehicle (HEV). Toyota Prius, representing this type of vehicle, showed outstanding performances in fuel efficiency, emission reduction and acceleration. The excellence is largely due to the fact that it utilizes almost all operation modes of HEV. Those modes include ZEV (Zero Emission Vehicle) driving, idle stop, fuel cut-off, power assist, active charging, regenerative braking and so forth. In this paper, a few of the mode operations were simulated using AVL Cruise. Also, control logics to operate the powertrain in each mode were developed. The states of powertrain components were displayed and analyzed. By controlling the three components (engine, motor and generator), it was possible to run the powertrain in several hybrid operation modes.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.547-550
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• 2006

The power split hybrid power train is considered to be one of the most prospective configuration for the hybrid electric vehicle (HEV). Toyota Prius, representing this type of vehicle, showed outstanding performances in fuel efficiency, emission reduction and acceleration. The excellence is largely due to the fact that it utilizes almost all operation modes of HEV. Those modes include ZEV (Zero Emission Vehicle) driving, idle stop, fuel cut-off, power assist, active charging, regenerative braking and so forth. In this paper, a few of the mode operations were simulated using AVL Cruise. Also, control logics to operate the powertrain in each mode were developed. The states of powertrain components were displayed and analyzed. By controlling the three components (engine, motor and generator), it was possible to run the powertrain in several hybrid operation modes.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.112-121
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• 2015

In this paper, powertrain of output split type plug-in hybrid electric vehicle is analyzed for the operation range of speed, torque, and power. First, it is assumed that the efficiency of motor is 100%. And, the speed and torque equations are derived based on the lever analogy. With the above equations, the simulations are performed for the powertrain of output split type plug-in hybrid electric vehicle. From the simulation results, it is found that the output torques of EV1 and series modes are larger than the EV2 and power split modes' ones. It means the EV1 and series modes can be used for the rapid acceleration. But the EV1 and series modes can be used only the velocity of under the 120 km/h. It is because the motor reaches its maximum speed when the velocity is over the 120 km/h for the EV1 and series modes. When the engine is turned on, the engine power is transmitted through the two motors. But, the power split mode shows the power split of engine at the output shaft, and it has the point of zero motor power. Thus, the transmission efficiency of the power split mode can be higher than the series mode's one, it the motor efficiency is considered.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.643-658
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• 2008

In this paper, we present a quadratic element model based on non-conforming displacement modes and modified shape functions. This new and refined 8-node hybrid stress plane element consists of two additional non-conforming modes that are added to the translational degree of freedom to improve the behavior of a membrane component. Further, the modification of the shape functions through quadratic polynomials in x-y coordinates enables retaining reasonable accuracy even when the element becomes considerably distorted. To establish its accuracy and efficiency, the element is compared with existing elements and - over a wide range of mesh distortions - it is demonstrated to be exceptionally accurate in predicting displacements and stresses.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1055-1070
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• 2016

The aim of this experimental study is to investigate the free vibration and buckling behaviors of hybrid composite beams having different span lengths and orientation angles subjected to different impact energy levels. The impact energies are applied in range from 10 J to 30 J. Free vibration and buckling behaviors of intact and impacted hybrid composite beams are compared with each other for different span lengths, orientation angles and impact levels. In free vibration analysis, the first three modes of hybrid beams are considered and natural frequencies are normalized. It is seen that first and second modes are mostly affected with increasing impact energy level. Also, the fundamental natural frequency is mostly affected with the usage of mold that have 40 mm span length (SP40). Moreover, as the impact energy increases, the normalized critical buckling loads decrease gradually for $0^{\circ}$ and $30^{\circ}$ oriented hybrid beams but they fluctuate for the other beams.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.27-33
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• 2013

In this study, the FMEA and FTA for reliability analysis of hybrid rocket motor are performed, that was designed in the Hybrid Rocket Propulsion Laboratory of Korea Aerospace University. In order to carry out these analyses the structure of the hybrid rocket motor is hierarchically divided into 36 parts down to the component level and FMEA is carried out with 72 failure modes. Reliability is assessed based on the FMEA, and the results are used in the FTA to evaluate the overall system reliability. In the FMEA, the relationship between the cause and failure modes, effects and their risk priorities are evaluated qualitatively. 27 failure modes are chosen as those with the critical severity that should be improved with priority. As a result of the FMEA / FTA study, a series of design or material changes are made for the improvement of reliability.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.733-738
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• 2016

We calculate optical properties of guided modes of a hybrid-guiding photonic crystal fiber. The design and modeling of such hybrid-guiding PCF is made by replacing air holes with inserts of high refractive index material layer by layer in order. The optical properties such as mode intensity profile, mode dispersion, optical birefringence, confinement loss, and chromatic dispersion during transition of the guiding mechanism are analyzed and discussed. The guided modes in the hybrid-guiding region are also compared with those of reference index-guiding and bandgap-guiding photonic crystal fibers.

• KIEAE Journal
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• v.4 no.3
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• pp.203-210
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• 2004

This dissertation identifies and investigates the possible control modes of hybrid ventilation system in applying to general apartments. It evaluates range of hybrid ventilation control modes in terms of indoor air quality, thermal comfort, and energy consumption in a living room and a kitchen of the $1000m^2$ apartment. The TRNSYS simulation program was used for evaluating the following four ventilation types : A ventilation mode relying on only infiltration for supplying air, A natural ventilation mode considering with weather condition, A hybrid ventilation (natural + mechanical ventilation) mode allowing minimum ventilation with no heat exchange, and a hybrid ventilation mode with heat exchange. This study shows the following results. As temperature being controlled by heating cooling equipments, there is without significant difference in thermal performance among ventilation types. Regarding Indoor Air quality, Indoor air contamination level of the hybrid ventilation case consistently keep the lower levels. The hybrid ventilation modes consume more energy by a 49% as compared to the A ventilation mode relying on only infiltration for supplying air. It is caused by the continuous ventilation for keeping good indoor air quality; the increase of energy consumption can be attributable to the increase of the heating energy. Therefore, the heat exchange between indoor and outdoor air is required during heating season in severe weather conditions. During the cooling seasons, Introducing natural ventilation can achieve energy saving by 40 ~ 45%. Thus, it can be an effective strategies for energy saving. Based on these results, a hybrid ventilation system can be suggested as an effective ventilation strategy for archiving high level of indoor air quality, thermal comfort, and energy consumption.

• Journal of Power Electronics
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• v.15 no.3
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• pp.849-859
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• 2015

This paper proposes a novel compound-type hybrid energy storage system (HESS) that inherits the unique advantages of both battery/supercapacitor (SC) and the SC/battery HESSs for electric vehicles (EVs). Eight operation modes are designed to match this system. A mode control strategy is developed for this HESS on the basis of these modes, and five classes of operation modes are established to simplify this strategy. The mode control strategy focuses on high operating efficiency and high power output. Furthermore, the compound-type HESS is designed such that the SC is the main priority in braking energy absorption. Thus, this HESS can operate efficiently and extend battery life. Simulation results also show that the compound-type HESS can not only supply adequate power to the motor inverter but can also determine suitable operation modes in corresponding conditions. Experimental results demonstrate that this HESS can extend battery life as well. The overall efficiency of the compound-type HESS is higher than those of the battery/SC and the SC/battery HESSs.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.40-48
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• 2019

Hybrid electric propulsion systems (H-EPSs) are an intermediate step for integrated full electric propulsion warships. H-EPSs are a dynamic combination of mechanical and electrical propulsion systems to achieve the required mission performances. The system modes could adapt to meet the requirement of the various operation conditions of a warship. This paper presents a configuration and operating modes of H-EPSs considering the operation conditions of a destroyer class warship. The system has three propulsion modes, namely, motoring mode, generating mode [power take off (PTO) mode], and mechanical mode. The PTO mode requires a careful fuel efficiency analysis because the fuel consumption rate of propulsion engines may be low compared with the generator's engines depending on the loading power. Therefore, the calculation of fuel consumption according to the operating modes is performed in this study. Although the economics of the PTO mode depends on system cases, it has an advantage in that it ensures the reliability of electric power in case of blackout or minimum generator operation.