• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.411-416
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• 2010

A voltage drop characteristics of a transformer-based voltage disturbance generator with series transformers is analysed. It is well known that a voltage disturbance generator with series transformer is cost-effective and reliable compared with other types. The voltage drop depends on the %Z of the transformer, power rating, and output power factor. A wrong design of the transformer results in a severe voltage drop, which can not guarantee the proper performance of the generator. The voltage drop is analysed under the condition of 10kVA output power rating and 4% of %Z with the variation of power factor. It is found through simulations and experiments that the drop increases as the power factor decreases in lagging mode, and the drop is 4% of the rated voltage in case of 0.85 lagging power factor.

• Journal of IKEEE
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• v.27 no.3
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• pp.273-279
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• 2023

The use of line memory is essential for image filtering in image processing hardware. After input data is stored in line memory, filtering is performed after synchronization to use the stored data. A sync generator is used for synchronization, and in the case of a conventional sync generator, the input sync signal is delayed by one row of the input image. If a signal delayed by two rows is required, it is necessary to connect two modules. This approach increases the size of the hardware and cannot be designed efficiently. In this paper, we propose a sync generator that generates multiple types of delayed signals by adding a finite state machine. The hardware design was coded in Verilog HDL, and performance is verified by applying it to image processing hardware using field programmable gate array board.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.171-178
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• 2005

An acoustic analysis of a fuel-rich gas generator for the drive of a turbopump in a liquid rocket engine has been performed and the length of a simulating duct has been determined by comparing the resonant frequency of unstable acoustic modes to simulate an actual flight model gas generator. To simulate more realistically, a realistic short-length simulating duct has been determined by considering 1 or 2 wavelength of the unstable modes. Duct-length adjustment to turbopump can be a method to suppress a combustion instability problem by decoupling of acoustic mode and combustion characteristics. This method has been set up and validated with acoustic analysis and hot firing tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.648-655
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• 2005

The resilient mounts of a diesel engine installed onboard a ship should be designed for both static and dynamic loads. If possible, the resonance frequencies of the six rigid body modes of the installation and the flexible modes of the engine support structure should not lie within the engine operation range. In this paper a design criterion is proposed to evaluate an isolation system which involves the summation of dynamic forces transmitted through the resilient mounts and elastic potential energy index stored in the mounts. A case study is also presented in which a diesel engine generator, which had an elastic foundation and was mounted in a 5500 TEU container vessel, was studied both theoretically and experimentally. The theoretical analysis of the test model was performed by using a single mass 6 degree of freedom system. Actual measurements of mechanical vibration of the Engine and its foundation onboard were carried out, which showed the importance of including the flexibility of the engine support structure in the mode

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.121-124
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• 2008

This paper presents experimental results of dynamic characteristics of fuel-rich gas generators. Pressure fluctuation measurements in the chamber and manifolds have been analyzed. Gas-generator-alone tests revealed stable combustion regardless of a chamber pressure but low-frequency combustion instabilities occurred for cases of turbine-manifold tests at chamber pressure conditions below 50 bar. The instabilities are considered as an axial resonant mode and acoustic intensity increases along with a chamber pressure.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.981-992
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• 2006

In this paper, a lateral vehicle control using the concept of control configured vehicle (CCV) is presented. The control objectives for the lateral dynamics of a vehicle include the ability to follow a chosen variable without significant motion change in other specified variables. The analysis techniques for decoupling of the aircraft motions are utilized to develop vehicle lateral control with advanced mode. Vehicle lateral dynamic is determined to have the steering input and control torque input. The additional vehicle modes are also defined to using CCV concept. We use right eigenstructure assignment techniques and command generator tracker to design a control law for an lateral vehicle dynamics. The desired eigenvectors are chosen to achieve the desired decoupling (i.e., lateral direction speed and yaw rate). The command generator tracker is used to ensure steady-state tracking of the driver's command. Finally, the developed design is utilized by using the lateral vehicle dynamic with four wheel.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1002-1011
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• 2006

In this paper, a lateral vehicle control using the concept of control configured vehicle(CCV) is presented. The control objectives for the lateral dynamics of a vehicle include the ability to commend a chosen variable without significant motion change in other specified variables. The analysis techniques fur decoupling of the aircraft motions are utilized to develop vehicle lateral control with advanced mode. Vehicle lateral dynamic is determined to have the steering input and control torque input. The additional vehicle modes are also defined to using CCV concept. We use right eigenstructure assignment techniques and command generator tracker to design a control law for an lateral vehicle dynamics. The desired eigenvectors are chosen to achieve the desired decoupling(i.e., lateral direction speed and yaw rate). The command generator tracker is used to ensure steady-state tracking of the driver's command. Finally, the developed design is utilized by using the lateral vehicle dynamic with four wheel.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.352-361
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• 2017

This paper proposes a design and fabrication of the test equipment that is implemented as a part of the airborne tracking radar inspection under the environment of indoor simulation. This test equipment provides controlling the operation status of airborne tracking radar and replicating the velocity and range information of target by generating a variety of target signal. This is mainly composed of radar operation controller, target signal generator, horn antenna driving devices. Radar operation controller is able to perform the controlling of radar operation mode and monitoring in real time by serial communication. Target signal generator is generated doppler signal and range delayed signal using virtual target of RF-band. Horn antenna driving devices perform a role of target simulating exercise. In the end, the performance is demonstrated using experiment results of test equipment for airborne tracking radar.

• Journal of Power Electronics
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• v.13 no.4
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• pp.619-625
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• 2013

Switched mode power supplies (SMPS) are power electronic circuits extensively used in a wide range of applications. High frequency switching operation of SMPS causes electromagnetic emissions and has the potential to interfere with system operation, which in turn has an impact on system performance. This makes electromagnetic compatibility (EMC) an important concern. In this paper, a new and simple spread spectrum technique is proposed by modulating chaotic pulse position modulation (CPPM) and pulse width modulation (PWM). The resulting CPWM is implemented to reduce the conducted EMI in SMPS. The proposed method is found to be effective in reducing conduction EMI. The effectiveness and simplicity of the proposed method on spreading those dominating frequencies is compared to the EMI mitigation technique using an external chaotic generator. Finally, the levels of conductive EMI with standard PWM, CPWM with an external chaos generator and the proposed method are experimentally verified to comply with the CISPR 22A regulations. The results confirm the effectiveness of the proposed method.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.39-44
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• 2013

In this paper digital phase-shifter for multi-arm spiral antennas was designed by using Hilbert transform. All frequency components in input signal are phase-shifted for 90 degree by Hilbert transform, and the transform is implemented by FIT and IFIT. Digital phase-shifter generates two signals with phase difference of 90 degree by using Hilbert transform from input signals sampled by analog-digital converter(ADC), and then the input signal is phase-shifted for a given phase by using two signals. Hilbert transform based on digital phase-shifter is designed by Xilinx System generator, and the effects of input noise, FIT point, sampling period, initial phase of input signal, and shifted phase are simulated and its results are compared with Matlab results.