• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.7
• /
• pp.1694-1704
• /
• 2015

In this paper, a robust trajectory tracking control method of a wheeled mobile robot is newly proposed combining the PDC and the ISMC. The PDC is a relatively simple and easy control method for nonlinear system compared to the other non-linear control methods. And the ISMC can have robust and stable control characteristics against model uncertainties and disturbances from the initial time by placing the states on the sliding plane with desired nominal dynamics. Therefore, the proposed PDC+ISMC trajectory tracking control method shows robust trajectory tracking performance in spite of external disturbance. The tracking performance of the proposed method is verified through simulations. Even though the disturbance increases, the proposed method keeps the performance of the PDC method when there is no disturbance. However, the PDC trajectory tracking control method has increasing tracking error unlike the proposed method when the disturbance increases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.372-378
• /
• 2005

Finite element analysis of concrete slab system in apartment building was executed using the tables of orthogonal arrays, and optimal design process was proposed. At first, experimental results show that sound peak components to influence the overall level and the rating of floor impact sound insulation were coincident with natural frequencies of the reinforced concrete slab. Finite element model of concrete slab was compared with experimental results, and well corresponded with an error of less than 10%. The tables of orthogonal arrays were used for finite element analysis with 8 factors. 3 related to material properties and 5 related to slab shape parameters and its results were analyzed by statistical method, ANOVA. The most effective factor among them was slab thickness, and main effect factor from slab shape parameters was different from each natural frequency. The interaction was found in the higher mode over $3^{rd}$ natural frequency. From main effect plot and interaction plot, the optimal design factor to increase the natural frequency was determined.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.05a
• /
• pp.149-152
• /
• 2009

Spray characteristic parameters such as droplet mean velocity, diameter, and volume flux are measured at various locations of spray in order to investigate the evolutionary feature of droplets exiting from a direct-injection type thruster nozzle-orifice. The experimental results indicate that the large droplets with high velocity at the center of upstream are broken-up into smaller droplets with low velocity due to their continuous momentum loss to surrounding air along with spray evolution toward downstream. Also it is found that the high volume flux expands its distribution in radial direction as a results of spray spreading and dispersion.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.9
• /
• pp.1617-1624
• /
• 2006

This paper presents system modeling, modified space vector PWM implementation and design of a closed loop controller of the Z-source inverter which consists of L and C components and shoot-through zero vectors for DGS. Zero vector periods of SVPWM utilized to boost DC-link voltage instead of conventional DC/DC converter and transformer. Only two shoot-through vut(nn are used for DC link voltage control during one switching period without loss of non-zero vectors. Discrete time sliding mode controller, robust servomechanism controller are designed to realize fast and no-overshoot current response and a steady state voltage error. Simulation results are shows the effectiveness of the proposed algorithm.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.6
• /
• pp.92-98
• /
• 1998

The transform limited optical short pulses are generated by compression of pulses from a gain switched distributed feedback laser at 5 GHz repetition rate. The gain-switched pulses have the minimum pulse width of 27 psec with the spectral width of 1.1 nm. Thus the output pulses have a large amount of linear chirp and nonlinear chirp. We suppress the nonlinear chirp by passing the pulses through the optical band pass filter with 3 dB band width of 0.55 nm which is narrower than spectral width of the input pulses and generate 7.1 psec pulses by compressing the output with the dispersion compensating fiber. The pulses have time-bandwidth product of 0.49 which is close to the transform limited gaussian pulse. These pulses can be utilized as optical sources in 40 Gbit/s time division multiplexed optical transmission system.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.2
• /
• pp.195-200
• /
• 2020

Leakage and Bragg condition of optical waveguides with blazed grating profile are evaluated in detail by using novel and rigorous modal transmission-line theory (MTLT) based on eigenvalue problem. The blazed waveguides classified as symmetric, sawtooth and asymmetric gratings occur leaky-wave stop-band at Bragg conditions and anomalies based on Rayleigh condition near Bragg conditions. Furthermore, DFB properties of blazed waveguides at Bragg conditions are analyzed by applying longitudinal equivalent transmission-line with characteristic impedance of periodic grating. The numerical results show that the reflected power of DFB waveguides is maximized at Bragg conditions in which leaky-wave stop-bands occur.

• Korean Journal of Optics and Photonics
• /
• v.14 no.1
• /
• pp.72-79
• /
• 2003

We proposed a noble algorithm using DOP (degree of polarization) not only as feedback signal but alto as feed-forward signal for the compensation of higher-order PMD effect. In the proposed algorithm, DOP after the first-order PMD compensation is considered as the indicator of the amount of residual higher-order PMD. This algorithm has the merit that DOF (degree of freedom) of the system can be limited to the level of the first-order PMD compensation system. Owing to the limited DOF, the reliability of the system can be enhanced and the complexity of the implementation can be degraded. For the analysis of the algorithm, we simulated the 10Gbps NRZ transmission system and obtained the result that the system outage probability can be reduced as much as three times with respect to the only first-order PMD compensation case.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1145-1146
• /
• 2006

분산 형 전원 및 석탄 가스화와 연계한 복합 발전이 가능한 용융탄산염 연료전지(MCFC : Molten Carbonate Fuel Cell)는 천연가스, 석탄가스 등 다양한 연료를 사용할 수 있고, 공해요인이 적고, 높은 에너지 변환효율을 가지고 있어 전력사업 분야에 적용 가능성이 가장 큰 새로운 발전방식이다. 국내에서도 1993년부터 선도기술개발 사업의 하나로 시작하여 현재 250 kW급 발전시스템 개발 연구가 진행되고 있다. 250 kW개발 전 수행한 100 kW급 MCFC 발전 시스템 개발 연구에서는 6,000cm2 급 단위전지 90장으로 구성된 50 kW급 MCFC 스택 2기 로 구성된 100 kW MCFC 스택과 이를 운전 평가를 위한 시스템을 완성하였다. 2005년부터 스택운전에 필요한 시스템 내 단위기기들에 대한 시운전을 진행 한 후 장착된 100 kW MCFC 스택 운전에서는 시스템 단위 기기의 고장으로 전 부하운전을 실시하지 못했지만 상압 상태에서 AC 50 kW 전력을 계통과 연계 운전 시험을 진행하였다. 향후 100 kW MCFC 시스템 보완후 재 운전 시험을 진행할 예정이다. 한편 병행하여 진행되는 250 kW 열병합 발전 시스템 개발에서는 시스템 상세설계 및 신형 분리판을 이용한 새로운 형태의 스택을 개발 운전시험을 진행하고 있다. 여기에서는 MCFC 발전 시스템의 개요와 시스템의 운전을 위한 운전 모드 그리고 스택 운전 내용을 요약하여 소개하고자 한다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.4
• /
• pp.168-178
• /
• 2008

The hybrid simulation test method is a versatile technique for evaluating the seismic performance of structures by seamlessly integrating both physical and numerical simulations of substructures into a single test mode. In this paper, a software framework that integrates computational and experimental simulation has been developed to simulate and test a bridge structural system under earthquake loading. Using hybrid simulation, the seismic response of complex bridge structural systems partitioned into multiple large-scale experimental and computational substructures at networked distributed experimental and computational facilities can be evaluated. In this paper, the examples of application are presented in terms of a bridge model with soil-foundation-structure interaction.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.10
• /
• pp.27-33
• /
• 1998

In this paper, we designed a demodulator using proposed synchronization techniques and algorithms for high-speed ATM satellite burst modem, and analyzed various performance in the AWGN channel. In addition, as the preamble progressed, each synchronization process can be analyzed by using the mean and variance characteristics, and the convergence state and operation state using convergence probability can also be determined. In conclusion, we analyzed the Cell Loss Ratio(CLR) by integrating the burst acquisition with Unique Word(UW) detector performance, and verified that proposed TDMA receiver satisfied the generally required CLR performance adequately.