• Journal of Institute of Control, Robotics and Systems
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• v.3 no.3
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• pp.311-317
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• 1997

DTG(dynamically tuned gyroscope) is a sensor detecting disturbance in angle velocity control loop of EOTS(electro optical tracking system), which is used for the stabilization of gimbal. DTG is classified into rate mode or rate integrated mode according to operating mode. In this paper, basic principles and characteristics of DTG, depending on to operating mode, are compared and the model of rate integrated mode DTG is proposed. Also, the validity of the presented model is verified by computer simulations and experiments.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.17-23
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• 2012

An integrated dynamic control (IDCF) with an active front steering system and an active rear braking system is proposed and developed in this study. A fuzzy logic controller is applied to calculate the desired additional steering angle and desired slip of the rear inner wheel. To validate IDCF system, an eight degree of freedom, nonlinear vehicle model and a sliding mode wheel slip controller are also designed. Various road conditions are used to test the performance. The results show that the yaw rate of IDCF vehicle followed the reference yaw rate and reduced the body slip angle, compared with uncontrolled vehicle. Thus, the IDCF vehicle had enhanced lateral stability and controllability.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.299-308
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• 2007

This study proposes a two-layer hierarchical control system that integrates active front wheel steering and four wheel braking torque control to improve vehicle handling performance and stability. The first layer is a robust model matching controller (R-MMC) based on linear matrix inequalities (LMIs), which optimizes an active front steering angle compensation and a desired yaw moment control, and calculates reference wheel slip for the target wheel according to the desired yaw moment. The second layer is a moving sliding mode controller (MSMC) that can track the reference wheel slip in a predetermined time by commanding proper braking torque on the target wheel to achieve the desired yaw moment. Since vehicle sideslip angle measurement is difficult to achieve in practice, a sliding mode observer (SMO) that requires only vehicle yaw rate as the measured input is also developed in this study. The performance and robustness of the SMO and the integrated control system are demonstrated through comprehensive computer simulations. Simulation results reveal the satisfactory tracking ability of the SMO, and the superior improved vehicle handling performance, stability and robustness of the integrated control vehicle.

• Current Optics and Photonics
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• v.7 no.6
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• pp.708-713
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• 2023

A robust all-fiber nonlinear amplifying loop-mirror-based mode-locked femtosecond laser is demonstrated. Power-dependent nonlinear phase shift in a Sagnac loop enables stable and power-efficient mode-locking working as an artificial saturable absorber. The pump power is adjusted to achieve the lowest intensity noise for stable long-term operation. The minimum pump power for mode-locking is 180 mW, and the optimal pump power is 300 mW. The lowest integrated root-mean-square relative intensity noise of a free-running mode-locked laser is 0.009% [integration bandwidth: 1 Hz-10 MHz]. The long-term repetition-rate instability of a free-running mode-locked laser is 10^-7 over 1,000 s averaging time. The repetition-rate phase noise scaled at 10-GHz carrier is -122 dBc/Hz at 10 kHz Fourier frequency. The demonstrated method can be applied as a seed source in high-precision real-time mid-infrared molecular spectroscopy.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.4
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• pp.387-394
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• 2013

As the feature size of integrated circuits continues to decrease, the challenge of achieving an oxidation-free exposed layer after photoresist (PR) stripping is becoming a critical issue for semiconductor device fabrication. In this article, the hydrogen plasma characteristics in direct plasma and the PR stripping rate in remote plasma were studied using a $120{\Phi}$ cylindrical inductively coupled plasma source. E mode, H mode and E-H mode transitions were observed, which were defined by matching the $V_{rms}$ and total impedance. In addition, the dependence of the E-H mode transition on pressure was examined and the corresponding plasma instability regions were identified. The plasma density and electron temperature increased gradually under the same process conditions. In contrast, the PR stripping rate decreased with increasing proportion of $H_2$ gas in mixed $H_2/N_2$ plasma. The decrease in concentration of reactive radicals for the removal of PR with increasing $H_2$ gas flow rate suggests that NH radicals have a dominant effect as the main volatile product.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.1
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• pp.1-21
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• 2013

The release of IEEE 802.15.4e specification significantly develops IEEE 802.15.4. The most inspiring improvement is the enhancement for medium access control (MAC) sublayer. To study the performance of IEEE 802.15.4e MAC, in this paper we first present an overview of IEEE 802.15.4e and introduce three MAC mechanisms in IEEE 802.15.4e. And the major concern here is the Time Slotted Channel Hopping (TSCH) mode that provides deterministic access and increases network capacity. Then a detailed analytical Markov chain model for TSCH carrier sense multiple access with collision avoidance (CSMA-CA) is presented. Expressions which cover most of the crucial issues in performance analysis such as the packet loss rate, energy consumption, normalized throughput, and average access delay are presented. Finally the performance evaluation for the TSCH mode is given and we make a comprehensive comparison with unslotted CSMA-CA in non-beacon enabled mode of IEEE 802.15.4. It can validate IEEE 802.15.4e network can provide low energy consumption, deterministic access and increase network capacity.

• ETRI Journal
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• v.26 no.3
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• pp.229-240
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• 2004

This paper reports on our development of a dual-mode transceiver for a CMOS high-rate Bluetooth system-onchip solution. The transceiver includes most of the radio building blocks such as an active complex filter, a Gaussian frequency shift keying (GFSK) demodulator, a variable gain amplifier (VGA), a dc offset cancellation circuit, a quadrature local oscillator (LO) generator, and an RF front-end. It is designed for both the normal-rate Bluetooth with an instantaneous bit rate of 1 Mb/s and the high-rate Bluetooth of up to 12 Mb/s. The receiver employs a dualconversion combined with a baseband dual-path architecture for resolving many problems such as flicker noise, dc offset, and power consumption of the dual-mode system. The transceiver requires none of the external image-rejection and intermediate frequency (IF) channel filters by using an LO of 1.6 GHz and the fifth order onchip filters. The chip is fabricated on a $6.5-mm^{2}$ die using a standard $0.25-{\mu}m$ CMOS technology. Experimental results show an in-band image-rejection ratio of 40 dB, an IIP3 of -5 dBm, and a sensitivity of -77 dBm for the Bluetooth mode when the losses from the external components are compensated. It consumes 42 mA in receive ${\pi}/4-diffrential$ quadrature phase-shift keying $({\pi}/4-DQPSK)$ mode of 8 Mb/s, 35 mA in receive GFSK mode of 1 Mb/s, and 32 mA in transmit mode from a 2.5-V supply. These results indicate that the architecture and circuits are adaptable to the implementation of a low-cost, multi-mode, high-speed wireless personal area network.

• 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.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.5-8
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• 2000

Voltage mode chaotic neuron has been designed in integrated circuit and fabricated by using 0.8$\mu\textrm{m}$ single poly CMOS technology. The fabricated CMOS chaotic neuron consist of chaotic signal generator and sigmoid output function. This paper presents an analysis of the chaotic behavior in the voltage mode CMOS chaotic neuron. From empirical equations of the chaotic neuron, the dynamical responses such as time series, bifurcation, and average firing rate are calculated. And, results of experiments in the single chaotic neuron and chaotic neural networks by two neurons are shown and compared with the simulated results.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.275-278
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• 2000

Recently ATM(Asynchronous Transfer Mode) technology is facing challenges from Integrated Service IP(Internet Protocol), IP router, Gigabit Ethernet. Although ATM is approved by ITU-T as the standard technology in B-ISDN, its survival is still in question. In the ATM networks, the Guaranteed Frame Rate(GFR) service has been designed to accommodate non-real-time applications, such as TCP(Transmission Control Protocol)/IP based traffic. The GFR service not only guarantees a minimum throughput at the frame level, but also supports a fairshare of available resources. We have studied different discarding and scheduling schemes, and compared their throughput and fairness when TCP/IP Traffic is carried. Through simulations, we know that only per-VC queueing with weighted Round Robin(WRR) can guarantee Minimum Cell Rate Among all the Schemes that have been experimented, we recommend DT-EPD(Dynamic Threshold-Early Packet Discard) integrated with MCRplus(Minimum Cell Rate) to support the GFR service.