• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.675-679
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• 2001

This paper presents walking algorithm for a quadruped robot that does not have an upper body. Tilting motion is added to the planned walking trajectory instead of using an extra body segment that is independent on walking trajectory. Area and tracking algorithms are proposed as tilting method and compared with that of off-line tilting and that of no tilting. Computer simulation shows that stability of tilted walking is more improved than that of the usual walking algorithm for general walking paths. It also shows that the tracking method guarantees stability and best mobility.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1719_1720
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• 2009

Wheeled mobile robot has different mobility and steerability which determined by type of wheel and it's arrangement. Generally wheeled mobile robot's dynamics are nonlinear and various control methods have studied to control the mobile robot efficiently. In this paper, a T-S fuzzy modeling of a 2-wheeled mobile robot is mand a stable LMI-based state feedback fuzzy controller is designed and applied to the position control of the mobile robot for the reference trajectory following. Also, the verification of the designed controller is done by computer simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1241-1245
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• 2009

As FFT(Fast Fourier Transform) processor is used in OFDM(Orthogonal Frequency Division Multiplesing) system. According to increase requirement about mobility and broadband, Research about low power and low area FFT processor is needed. So research concern in reduction of memory size and complex multiplier is in progress. Increasing points of FFT increase memory area of FFT processor. Specially, SRU(Signal Reordering Unit) has the most memory in FFT processor. In this paper, we propose a reduced method of memory size of SRU in FFT processor. SRU of 64, 1024 point FFT processor performed implementation by VerilogHDL coding and it verified by simulation. We select the APEX20KE family EP20k1000EPC672-3 device of Altera Corps. SRU implementation is performed by synthesis of Quartus Tool. The bits of data size decide by 24bits that is 12bits from real, imaginary number respectively. It is shown that, the proposed SRU of 64point and 1024point achieve more than 28%, 24% area reduction respectively.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.12 no.2
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• pp.119-131
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• 2008

The paper considers the computation method in the performance evaluation of cellular network in the phase-type distribution assumptions that the channel holding times induced from mobility are modeled by well-fitted distributions to reflect an actual situation. When ww consider a phase-type distribution model instead of exponential distribution, the complexity of the computation increase exponential even though the accuracy is improved. We consider an efficient numerical algorithm to compute the performance evaluations in cellular networks such as a handoff call dropping probability, new call blocking probability, and handoff arrival rate. Numerical experiment shows that numerical analysis results are well approximated to the results of simulation.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.775-782
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• 2005

The service of wireless network has problems due to low bandwidth, frequent disconnection, low packet transport and user' mobility. In this paper, we proposed the cooperative methods of update to perform efficiently wireless network services. The proposed method performs the updates by cooperative filtering and streaming by $mbuffer_{in}$ and $mbuffer_{out}$. The simulation results show performance improvement of the proposed method compared to others.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.677-681
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• 2009

The Smoothly Coupled Integration (SCI) proposed in this paper takes only the strength of loosely coupled integration and tightly coupled integration. Furthermore, 3G network and WiBro network, which are coupled with SCI, have independent architecture which supports mobility and seamless services by fast handoff. Computer simulation with the use of OPNET marked excellence in performance of smoothly coupled integration.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1489-1498
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• 2015

Gallium nitride (GaN)-based power switching devices, such as high-electron-mobility transistors (HEMT), provide significant performance improvements in terms of faster switching speed, zero reverse recovery, and lower on-state resistance compared with conventional silicon (Si) metal-oxide-semiconductor field-effect transistors (MOSFET). These benefits of GaN HEMTs further lead to low loss, high switching frequency, and high power density converters. Through simulation and experimentation, this research thoroughly contributes to the understanding of performance characterization including the efficiency, loss distribution, and thermal behavior of a 160-W GaN-based synchronous boost converter under various output voltage, load current, and switching frequency operations, as compared with the state-of-the-art Si technology. Original suggestions on design considerations to optimize the GaN converter performance are also provided.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1680-1682
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• 2007

The integrated circuits such as inverters, ring oscillators, NAND and NOR gates, and rectifiers were fabricated on PEN substrate by using pentacene TFTs. The OTFTs used bottom contact structure and produced the average mobility of $0.26\;cm^2/V.sec$ and on/off current ratio of $10^5$. All circuits worked successfully like the simulation results. Especially, the rectifier was able to operate up to 1 MHz input signals, and ring oscillator exhibited oscillation frequency of 1MHz at-40V.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3C
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• pp.211-219
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• 2002

Mobile IP(RFC2002) is representative protocols that support mobility to host. In this paper, we propose a mobile IP registration protocol using public-key based certificates and CA(certification authority). Our proposed protocol authenticates the registration message of mobile node and prevents replay attack and minimal use of public key cryptography, Also, Our proposed protocol directly authenticates between agents and mobile nodes using certificates. Though the computer simulation, we prove that our proposal has better performance than the previous public-key based Mobile IP registration protocol.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.128-131
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• 2007

As the minimum feature size decrease, control of contamination by nanoparticles is getting more attention in semiconductor process. Cleaning technology which removes nanoparticles is essential to increase yield. A reference wafer on which particles with known size and number are deposited is needed to evaluate the cleaning process. We simulated particle trajectories in the chamber by using FLUENT. Charged monodisperse particles are generated using scanning mobility particle sizer (SMPS) and deposited on the wafer by electrostatic force. The experimental results agreed with the simulation results well. We calculate the particles loss in pipe flow theoretically and compare with the experimental results.