• Journal of the Korean Society of Combustion
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• v.20 no.4
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• pp.10-18
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• 2015

Combustion instability is a major issue in design and maintenance of gas turbine combustors for efficient operation with low emissions. With the thermoacoustic view point the instability is induced by the interaction of the unsteady heat release of the combustion process and the change in the acoustic pressure in the combustion chamber. In an effort to study the combustion dynamics of gas turbine combustors, Morgans et al (2014) have developed OSCILOS (open source combustion instability low order simulator) code and it is currently available online. In this study the code has been utilized to predict the combustion instability of a reported case for lean premixed gas turbine combustion, and then its prediction results have been compared with the corresponding experimental data. It turned out that both the predicted and the experimental combustion instability results agree well. Further the effects of some typical inlet acoustic boundary conditions on the prediction have been investigated briefly. It is believed that the validity and effectiveness of the open source code is reconfirmed through this benchmark test.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.1
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• pp.46-52
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• 2004

In this paper, we introduce a case study of developing a miniature humanoid robot which has 16 degrees of freedom, 42 cm heights, and 1.5kg weights. For easy implimentation, the integrated RC-servo motors are adopted as actuators and a digital camera is equipped on its head. So, it can transmit vision data to a remote host computer via wireless modem. The robot can perform staircase walking as well as straight walking and turning to any direction. The user-interface program running on the host computer contains a robot graphic simulator and a motion editor which are used to generate and verify the robot's walking motion. The experimental results show that the robot has various walking capability including straight walking, turning, and stairs walking.

• Proceedings of the IEEK Conference
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• summer
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• pp.199-203
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• 2004

In this paper, we only describe the digital block of two-channel 18-bit analog-to-digital (A/D) converter employing sigma-delta method and xl28 decimation. The device contains two fourth comb filters with 1-bit input from sigma­delta modulator. each followed by a digital half band FIR(Finite Impulse Response) filters. The external analog sigma-delta modulators are sampled at 6.144MHz and the digital words are output at 48kHz. The fourth-order comb filter has designed 3 types of ways for optimal power consumption and signal-to-noise ratio. The following 3 digital filters are designed with 12tap, 22tap and 116tap to meet the specification. These filters eliminate images of the base band audio signal that exist at multiples of the input sample rate. We also designed these filters with 8bit and 16bit filter coefficient to analysis signal-to-noise ratio and hardware complexity. It also included digital output interface block for I2S serial data protocol, test circuit and internal input vector generator. It is fabricated with 0.35um HYNIX standard CMOS cell library with 3.3V supply voltage and the chip size is 2000um by 2000um. The function and the performance have been verified using Verilog XL logic simulator and Matlab tool.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.23-30
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• 1993

This rape deals with the experimental and theoretical investigations on the aerodynamic performance of the Wells turbine. The two-dimensional cascade theory is used to estimate the thrust and torque of turbine, and finally to yield an efficiency of turbine. The turbine is assumed to rotate with a constant rotational speed in a sinusoidally varying unsteady flow field. Experimental approach is made in a wave simulator, producing a sinusoidally reciprocating air flow corresponding to the wave motion in an Oscillating Water Column(OWC) chamber. Performance data of turbine measured at various operating conditions are analyzed and compared to numerical results in order to understand the overall features of a Wells turbine.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.72-80
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• 2001

In this paper, we present a systematic method of extracting the input parameters of poly-Si TFT(Thin-Film Transistor) for Spice simulations. This method has been applied to two different types of poly-Si TFTs such as ELA (Excimer Laser Annealing) and SMC (Silicide Mediated Crystallization) with good fitting results to experimental data. Among the Spice circuit simulators, the PSpice has the GUI(graphic user interface) feature making the composition of complicated circuits easier. We added successfully the poly-Si TFT model of AIM-Spice to the PSpice simulator, and analyzed easily to compare the electrical characteristics of pixels without or with the line RC delay. In the comparative results, the ELA poly-Si TFT is superior to the SMC poly-Si TFT in the charging time and the kickback voltage for the TFT-LCD (Thin Film Transistor-Liquid Crystal Display).

• Journal of IKEEE
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• v.24 no.1
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• pp.333-338
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• 2020

This paper proposes a method of estimating the SOC(State of Charge) of a battery cell using a neural network algorithm. To this, we implement a battery SOC estimation simulator and derive input and output data for neural network learning through charge and discharge experiments at various temperatures. Finally, the performance of the battery SOC estimation is analyzed by comparing with the experimental value by Ah-counting using Matlab/Simulink program and confirmed that the error rate can be reduced to less than 3%.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.88-96
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• 2009

Interoperation between heterogeneous simulators employs definition of standard protocols for data exchange and time synchronization among simulators. The High Level Architecture(HLA) is a specification of common services for such interoperation, which is approved as IEEE standard 1516. This paper presents the design and implementation of an interoperable adaptor which supports development of interoperable simulators under the IEEE 1516 HLA/RTI environment. The adaptor, KHLAAdaptor1516, is implemented as a library form which is linked to HLA-compliant simulators. Design of the adaptor employs a protocol conversion method, the model of which is finite state machine. KHLAAdaptor1516 allows developers to separate interoperable adaptors from stand-alone simulators. The interoperable adaptor manages mapping between HLA services and simulation messages for simulator, This separation increases robustness of a federation and reusability of simulators as well as alleviates much effort and time for maintenance.

• Journal of Navigation and Port Research
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• v.33 no.9
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• pp.609-614
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• 2009

The traffic of tug/barges which are carrying construction materials, large plants for harbor development, or offshore structures has recently increased in the coast of Korea. The west and south coast of Korea are always congested due to a lot of islands and traffic concentration. Specially tug/barges have higher probability of marine accidents due to their bad maneuverability than others. Considering the operational circumstance and maneuverability, this study was to develop a wide-area monitoring and control system for tug/barges in the coastal area of Korea. The system was made in the form of three program modules i.e. navigation analysis program module, monitoring and control program module, database module. And seven functions were programmed to monitor and control the tug/barges efficiently. These are ship information search, tug/barge information and track management, designated area and safe navigation zone management, fairway management, accident data management, warning of danger, safety information management.

• Journal of Power Electronics
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• v.3 no.1
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• pp.62-67
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• 2003

Recently, photovoltaic system has been studied widely as a renewable energy system, because it does not produce environmental pollution and it has infinity energy source from the sun. A study on photovoltaic system has a lot of problems like as reappearance and repetition of some situation in the laboratory experiment for development of MPPT algorithm and islanding detection algorithm. because output characteristics of solar cell are varied by irradiation and surface temperature of solar cell. Therefore, the assistant equipment which emulates the solar cell characteristics which can be controlled arbitrarily by researcher is require to the researchers for reliable experimental data. In this paper, the virtual implement of solar cell (VISC) system is proposed to solve these problems and to achieve reliable experimental result on photovoltaic system. VISC system emulates the solar cell output characteristics, and this system can substitute solar cell in laboratory experiment system. To realize the VISC, mathematical model of solar cell is studied for driving converter and the DC/DC converters are compared in viewpoint of tracking error using computer simulation. Output dynamic characteristic of PV array is varied by irradiation and PWM converter performance is studied using PSIM simulator.

• Journal of Communications and Networks
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• v.15 no.4
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• pp.422-429
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• 2013

Advances in wireless sensor network (WSN) technology have enabled small and low-cost sensors with the capability of sensing various types of physical and environmental conditions, data processing, and wireless communication. In the WSN, the sensor nodes have a limited transmission range and their processing and storage capabilities as well as their energy resources are limited. A triple umpiring system has already been proved for its better performance in WSNs. The clustering technique is effective in prolonging the lifetime of the WSN. In this study, we have modified the ad-hoc on demand distance vector routing by incorporating signal-to-noise ratio (SNR) based dynamic clustering. The proposed scheme, which is an efficient and secure routing protocol for wireless sensor networks through SNR-based dynamic clustering (ESRPSDC) mechanisms, can partition the nodes into clusters and select the cluster head (CH) among the nodes based on the energy, and non CH nodes join with a specific CH based on the SNR values. Error recovery has been implemented during the inter-cluster routing in order to avoid end-to-end error recovery. Security has been achieved by isolating the malicious nodes using sink-based routing pattern analysis. Extensive investigation studies using a global mobile simulator have shown that this hybrid ESRP significantly improves the energy efficiency and packet reception rate as compared with the SNR unaware routing algorithms such as the low energy aware adaptive clustering hierarchy and power efficient gathering in sensor information systems.