• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.115-125
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• 2003

To analyze the applications of all types of mechanical systems, general purpose analysis programs have been developed and commercialized. However, it is customary to develop and use customized programs even though they sometimes require more work than a general purpose program. A customized program is simplified to adapt to a particular application from the beginning, is designed for small computers, and developed with hardware-in-the-loop in mind so it can be applied effectively. By adding design knowledge and bundling know-how to an analysis program, analysis time can be reduced. And because an analysis has to work in conjunction with other analysis programs, a proprietary program that the user can easily modify can be useful. In this thesis, a multi-body dynamics analysis system is presented using one of the most useful programming techniques, object-oriented concept. The object-oriented concept defines a problem from the physical world as an abstract object, an abstract model. The object becomes encapsulated with the data and method. Simulation is performed using the object's interface. It is then possible for the user and the developer to modify and upgrade the program without having particular knowledge of the analysis program. The method presented in this thesis has the following advantages. Since the mechanical components of the multi-body system converts independent modeling into a class, the modification, exchange, distribution, and reuse of elements are increased. It becomes easier to employ a new analysis method and interface with other S/W and H/W systems. To employ a new analysis method, there is no need to modify elements of the main solver and the Library. In addition, information can be communicated to each object through messaging. It makes the modeling of new elements easier using inheritance. When developing a S/W for the computer simulation of physical system, it is reasonable to use object-oriented modeling. Also, for multi-body dynamics analysis, it is possible to develop a solver that is user-oriented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.857-866
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• 2022

Fixed-wing UAVs have long endurance and range capabilities compared to other aerial platforms. These advantages led fixed-wing UAVs to become a popular platform for reconnaissance missions in the military. In this research, we modeled fixed-wing UAVs, including the landing gear model and developed a guidance and control system for flight control computers to construct a HILS environment. We also developed an autopilot system that includes automated take-off, cruise, and landing control for UAVs. We also retrived the Aerodynamic coefficients an UAV using Datcom and AVL software and used them for 6 degrees of freedom modeling. The Flight control computer calculates guidance commands using the Carrot chasing guidance law after distinguishing the condition of the UAV based on 16 pre-defined flight modes and calculates control inputs using Nonlinear Dynamic Inversion (NDI) control scheme. We used RTNngine to integrate the Simulink model and flight control computer for HILS environment formulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.33-39
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• 2022

A multi-phase brushless direct current (BLDC) motor is widely used in large-capacity electric propulsion systems such as submarines and electric ships. In particular, in the field of military submarines, the polyphaser motor must suppress torque ripple in various failure situations to reduce noise and ensure stable operation for a long time. In this paper, we propose a polyphaser current control method that can improve efficiency and reduce torque ripple by minimizing the increase in stator winding loss at maximum output torque by controlling the phase angle and amplitude of the steady-state current during open circuit failure of the stator winding. The proposed control method controls the magnitude and phase angle of the healthy phase current, excluding the faulty phase, to compensate for the torque ripple that occurs in the case of a phase open failure of the motor. The magnitude and phase angle of the controlled steady-state current are calculated for each phase so that copper loss increase is minimized. The proposed control method was verified using hardware-in-the-loop simulation (HILS) of a 12-phase BLDC motor. HILS verification confirmed that the increase in the loss of the stator winding and the magnitude of the torque ripple decreased compared with the open phase fault of the motor.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.189-198
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• 2015

Most IoT-related approaches have tried to establish the relation by connecting the network between things. The proposed research will present how the pervasive interaction of eco-system formed by touching the objects between humans and things can be recognized on purpose. By collecting and sharing the detected patterns among all kinds of things, we can construct the environment which enables individualized interactions of different objects. To perform the aforementioned, we are going to utilize technical procedures such as event-driven signal processing, pattern matching for signal recognition, and hardware in the loop simulation. We will also aim to implement the prototype of sensor processor based on Arduino MCU, which can be integrated with system using Arduino-Matlab/Simulink hybrid-interoperation environment. In the experiment, we use piezo transducer to detect the vibration or vibrates the surface using acoustic wave, which has specific frequency spectrum and individualized signal shape in terms of time axis. The signal distortion in time and frequency domain is recorded into memory tracer within sensor processor to extract the meaningful pattern by comparing the stored with lookup table(LUT). In this paper, we will contribute the initial prototypes for the acoustic touch processor by using off-the-shelf MCU and the integrated framework based on Matlab/Simulink model to provide the individualization of the touch-sensing for the user on purpose.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.83-91
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• 2012

In recent days, the study on hybridization of the heavy-duty is going on, actively. Especially, the improvement of fuel economy can be maximized in the intra-city bus because it drives the fixed route. For developing the hybrid electric intra-city bus, optimized control strategy which is possible to be applied with real vehicle is necessary. If the real-time control strategy is developed based on the HILS, it is possible to verify the real-time ability and fail-safety function which has the vehicle stay in safe state when the functional errors are occurred. In this study, the HILS system of series hybrid electric intra-city bus is developed to verify the real time control strategy and the fail-safety functions. The main objective of the paper is to build the HILS system for verifying the control strategy (rule-based control) which is implemented to reflect the Dynamic Programming results and fail-safety functions.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.429-440
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• 2007

A coded excitation has been studied to improve the performance for ultrasound imaging in term of SNR, imaging frame rate, contrast to tissue ratio, and so forth. However, it requires a complicated arbitrary waveform transmitter for each active channel that is typically composed of a multi-bit Digital-to-Analog Converter (DAC) and a linear power amplifier (LPA). Not only does the LPA increase the cost and size of a transmitter block, but it consumes much power, increasing the system complexity further and causing a heating-up problem. This paper proposes an optimized 1.5bit fourth order sigma-delta modulation technique applicable to design an efficient arbitrary waveform generator with greatly reduced power dissipation and hardware. The proposed SDM can provide a required SQNR with a low over-sampling ratio of 4. To this end, the loop coefficients are optimized to minimize the quantization noise power in signal band while maintaining system stability. In addition, the decision level for the 1.5 bit quantizer is optimized for a given input waveform, which results in the SQNR improvement of more than 5dB. Computer simulation results show that the SQNR of a FM(frequency modulated) signal generated by using the proposed method is about 26dB, and the peak side-lobe level (PSL) of its compressed waveform on receive is -48dB.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.451-456
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• 2018

UAComm (Underwater Acoustic Communication) is an active research area, and many experiment has been performed to develop UAComm system. In this paper, we investigate the possibility of modifying and applying VirTEX (Virtual Time series EXperiment) to medium long range MIMO (Multiple-Input Multiple-Output) UAComm of about 20 km range for the analysis and performance prediction of UAComm system. Since VirTEX is a time-domain simulator, the generated time series can be used in HILS (Hardware In the Loop Simulation) to develop UAComm system. The developed package is verified through comparing with the sea-going FAF05 (Focused Acoustic Field 2005) experimental data. The developed simulator can be used to predict the performance of UAComm system, and even replace the expensive sea-going experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.7
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• pp.701-708
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• 2009

The flight control law of developed flight control computer(DFLCC) is developed based on operation flight program of advanced trainer aircraft full scale development final configuration. The flight control law design is used common use development tool in GUI(Graphic User Interface) environment. The flight control law transformed to C-Code is reflected in OFP. The OFP is verified by the standardized verification process. But, before standardized verification process, we need preliminary verification process such as similarity of flight control law and reliability of developed HILS. Similarity of flight control law is verified by comparing the aircraft response of advanced trainer aircraft and those of the developed control law. Also, reliability of developed HILS is verified by comparing the aircraft response of HILS and Non-real time simulation result. This paper verifies similarity of developed control law and reliability of HILS environment as comparing aircraft response.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1183-1194
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• 2021

Traditionally, electric power systems have been known as the centralized structures, which is organized into placing customers at the end of the supply chain. However, recent decades have witnessed the emergence of distributed energy resources(:DERs) such as rooftop solar, farming PV system, small wind turbines, battery energy storage systems and smart home appliances. With the emergence of distributed energy resources, the role of distributed system operators(:DSOs) will expand. The increasing penetration of DERs could lead to a less predictable and reverse flow of power in the system, which can affect the traditional planning and operation of distribution and transmission networks. This raises the need for a change in the role of the DSOs that have conventionally planned, maintained and managed networks and supply outages. The objective of this research is to designed the future distribution operation system with multi-DERs and the proposed distribution system model is implemented by hardware-in-the-loop simulation(HILS). The test results show the normal operation domain and reduction of distribution line loss.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1615-1621
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• 2014

A wireless tram which runs without catenary and instead uses batteries installed in the tram has been recently researched actively. This paper presents a new method maximizing absorption of regenerative energy of a wireless tram and extending life cycle of the energy storage device in the wireless tram by applying line-optimized charging and discharging scenario. Energy efficiency and life cycle of energy storage system (ESS) are highly dependent on the characteristic of operating conditions. For example, frequent charge and discharge with high power cause the problems that decrease the battery life cycles. Hybrid energy storage system (HESS) is combination of two ESSs which have complementary characteristics to each other. HESS can provide even better functionality and performance than the battery only ESS due to the synergy effect of two ESSs. This paper also provides a power distribution strategy and driving scenarios which increase the life cycle and energy efficiency of the HESS consisting of a battery and an ultra-capacitor. The developed strategy was tested and verified by a hardware-in-the-loop-simulation (HILS) system which emulates the a wireless tram.