• Journal of Power Electronics
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• v.12 no.6
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• pp.935-946
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• 2012

A new kind of resonant impedance type hybrid active filter (RITHAF) is proposed for dynamic harmonic current suppression and high capacity reactive compensation in medium and high voltage systems. This paper analyzed the different performance of the RITHAF when the active part of the RITHAF is controlled as a current source and as a voltage source, respectively. The harmonic suppression function is defined in this paper. The influences of the changes caused by the grid impedance and the detuning of the passive power filter on the compensating characteristics of the RITHAF are studied by analyzing the suppression function. Simulation and industrial application results show that the RITHAF has excellent performances in harmonic suppression and reactive compensation, which is suitable for medium and high voltage systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2147-2153
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• 2009

A Hybrid type Linear Pulse Motor(LPM) for low cost is designed as single side stator structure. The static and dynamic characteristics measurement systems are designed. Experimental measurement systems, which measure the static and dynamic characteristic of the LPM, are uggested for the prototype LPM. It becomes known the values of the thrust forces. Finally the microstep drive method is adopted to the drive of prototype LPM. The waveform difference is measured between the microstep method and rectangular wave. From the experimental results, it can be confirmed that the repetitive ripple of the thrust force of the prototype LPM are reduced by taking the microstep drive method.

• Journal of Power Electronics
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• v.10 no.6
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• pp.769-776
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• 2010

The ultracapacitor module has recently been recast for use in hybrid energy storage systems (HESSs). As a result, accurate state-of-charge (SOC) estimation for an ultracapacitor module is as important as that of primary sources in order to be utilized efficiently in an energy storage system (ESS). However, while SOC estimation via the open-circuit voltage (OCV) method is generally used due to its linear characteristics compared with other ESSs, this method results in many errors in cases of highcurrent charging/discharging within a short time period. Accordingly, this paper introduces a dynamic SOC estimation algorithm that is capable of SOC compensation of an ultracapacitor module even when there is a current input and output. A cycle profile that simulates the operating conditions of a mild-HEV was applied to a vehicle simulator to verify the effectiveness of the proposed algorithm.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.133-140
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• 2018

Recently, environmentally friendly aviation propulsion systems have received a lot of attention. Therefore, many studies have been conducted on the development of UAVs and propulsion systems that can perform missions while relying on a combination of various power sources. In this paper, we show the design results of a hybrid propulsion system based on solar-power generation. It integrates a single system to test reliability and performance. Finally, a verification test is conducted on the aircraft to confirm the function and normal operation of the system before a flight test.

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.362-371
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• 2022

As considerable interests in noise emission from the ships have been increased, International Maritime Organization (IMO) standardized the Underwater Radiated Noise (URN) measurement process of commercial ships in deep seas by enacting the related ISO standard ISO 17208-1 and classification societies responded with the enactment or revision of corresponding notations. According to this trend, a new hybrid underwater sound propagation model based on underwater sound propagation theories was developed and its accuracy on analysis was verified through the result comparison with the results of other generally used models. Using the verified model, each URN propagation characteristics adjusted by the correction methods proposed in the ISO standard and class notations were analyzed and compared in two assumed URN measurement cases. The results showed that the effects of transmission loss corrections in the circumstances with less bottom reflections generally similar but they had rather large differences in the model analysis results with bottom-reflection-dominant conditions. It was concluded that the deep consideration of effective bottom-reflection-correction method should be made in future revisions of ISO standard and class notations.

• Journal of the Korean Wood Science and Technology
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• v.51 no.6
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• pp.526-541
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• 2023

Wooden structures are widely used, particularly in earthquake zones, owing to their light weight, ease of application, and resistance to the external environment. In this study, we aimed to improve the mechanical properties of laminated timber beams using novel hybrid systems [carbon-fiber-reinforced polymer (CFRP) and wire rope]. Within the scope of this study, it is expected that using wood, which is an environmentally friendly and sustainable building element, will be more economical and safe than the reinforced concrete and steel elements currently used to pass through wide openings. The structural behavior of the hybrid-reinforced laminated timber beams was determined under the loading system. The experimental findings showed that the highest increase in the values of laminated beams reinforced with steel ropes was obtained with the 2N reinforcement, with a maximum load of 38 kN and a displacement of 137 mm. Thus, a load increase of 168% and displacement increase of 275% compared with the reference sample were obtained. Compared with the reference sample, a load increase of 92% and a displacement increase of 14% were obtained. Carbon fabrics placed between the layers with fiber-reinforced polymer (FRP) prevented crack development and provided significant interlayer connections. Consequently, the fabrics placed between the laminated wooden beams with the innovative reinforcement system will not disrupt the aesthetics or reduce the effect of earthquake forces, and significant reductions can be achieved in these sections.

• International Journal of Computer Science & Network Security
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• v.24 no.6
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• pp.33-40
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• 2024

Introducing renewable energy sources, such as wind and photovoltaic arrays, in microgrids that supply remote regions with electricity represents a significant leap in electricity generation. Combining photovoltaic panels and diesel engines is one of the most common ways to supply electricity to rural communities. Such hybrid systems can reduce the cost of electricity generation in these remote power systems because they use free energy to balance the power generated by diesel engines. However, the combination of renewable energy sources and diesel engines tends to complicate the sizing and control of the entire system due to the intermittent nature of renewable energy sources. This study sought to investigate this issue in depth. It proposes a robust hybrid controller that can be used to facilitate optimum power sharing between a PV power source and diesel generators based on the dynamics of the available PV energy at any given time. The study also describes a hybrid PV-diesel power plant's essential functional parts that produce electricity for a microgrid using a renewable energy source. Power control needs to be adjusted to reduce the cost of power generation.

• Smart Structures and Systems
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• v.33 no.6
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• pp.431-447
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• 2024

The Hybrid Mass Damper (HMD) has proven effective in mitigating vibrations in high-rise structures subject to seismic and wind-induced excitations. One derivative configuration of the HMD mounts an Active Mass Damper (AMD) atop a Tuned Mass Damper (TMD). However, the control efficacy of such HMDs may be compromised when confronted with loads that exceed their design parameters. Additionally, the confined structural space within high-rise structures often limits the feasibility and economic viability of retrofitting HMD systems. This study introduces an Acceleration-based Fuzzy Power Approach Rate Sliding Mode Control (AFP-SMC) algorithm aimed at enhancing the control efficacy of HMDs while minimizing their stroke and force output requirements. Employing the Canton Tower as a research prototype, an analytical model incorporating HMDs was established, and a comparative analysis between the AFP-SMC and Linear Quadratic Gaussian (LQG) control algorithms was conducted for efficacy. The control performance of the AFP-SMC control algorithm under different control parameter variations was investigated. Furthermore, by experimentally assessing the AMD subsystem within the Canton Tower, friction and ripple force formulas were derived to bolster the analytical model, thereby validating the robustness of the AFP-SMC algorithm. The results show that the proposed AFP-SMC algorithm effectively reduces the vibration response of the structure and the stroke and control force output of HMDs, and exhibits superior overall control performance and robustness compared to the LQG algorithm.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.33-43
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• 2010

This paper deals with the hybrid structural test technique which has been introduced and studied currently in Korea. In this study, a Mini-MOST system which was developed as a part of NEES research was modified and improved to reduce the total simulation time to half of the original system. Using the proposed system together with the 2 dimensional small steel frame specimen, the validity and efficiency of the hybrid test technique is investigated. Even though the hybrid test has been developed as an alternative to the shaking table test and has been studied and applied for a long time in several countries, no attempt has been made to compare it directly with the shaking table test. Therefore, in this study, the hybrid test results are compared with those of the shaking table test as well as with a numerical simulation for the verification of hybrid test. From the comparison and analysis of the test results, it is concluded that the hybrid test can simulate the actual seismic behavior of structural systems very accurately and it can be a good alternative to the shaking table test.