• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1853-1857
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• 2005

In most of motor-driven motion control systems, an encoder is used to measure a position of the motor and the velocity information is obtained by measuring the position increment over a sampling period. The quantization effect due to limited resolution of the encoder induces some measurement errors, and consequently causes deterioration of the motion performance especially in low velocity. In this paper, we propose a gain-scheduled acceleration estimator which works in wider velocity range than the original acceleration estimator. We investigate and analyze characteristics of the velocity measurement mechanism which takes into account the quantization effect of the encoder. Next, we introduce the acceleration estimator and propose a gain-scheduled acceleration estimator. The bandwidth of the gain-scheduled acceleration estimator is automatically adjusted by the velocity command. Finally, its performance is evaluated by simulation and experiment, and the results are compared with those of a conventional method and the original acceleration estimator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.283-289
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• 2003

In this paper, we proposed novel multilayer photonic bandgap(PBG) structure using DSL(Descended Signal Line). From measurement result, the proposed PBG structure using DSL is reduced 72 % at size and increased 13 % at bandwidth compared to typical multilayer DGS(Defected Ground Structure). It is also reduced 42 % at size and increased 23 % at bandwidth compared to PBG structure using EGP(Elevated Ground Plane). In case of measurement for manufactured six PBG patterns, all patterns have the same cutoff frequency and bandstop characteristics. So it can be used for bandstop filter having very precise tolerance of below 300 MHz at 20 ㎓ if it is applied to real product and this filter will be useful for small microwave integrated circuit and module development.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.153-156
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• 2000

The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 30 MHz to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cutting com-shaped type satisfying the above requirments and carried out broadband design using the equivalent material constants method. Moreover, we have fabricated it and compared its characteristics with simulated one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.372-378
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• 2000

The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMI/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 30 MHz to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cross-shaped type and tapered cross-shaped type absorbers satisfying the above requirments and carried out broadband design using the equivalent material constants method. Futheremore, the results have been compared with FEM, and FDTD.

• Journal of Sensor Science and Technology
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• v.4 no.1
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• pp.15-20
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• 1995

This paper deals with the planar-type sensor which can measure the time-varying electric fields. To make an electric field measurement system having a wide bandwidth, a planar-type sensor is proposed. The theoretical principle and design rule of the measuring device are introduced, and also the calibration and application investigations are carried out. From the calibration experiments, the frequency bandwidth of the electric field measurement device ranges from 160 [Hz] to 25 [MHz] and the sensitivity of the sensor is 1.2 [mV/V/m]. As the application experiments, the electric fields caused by the impulse and oscillating transient voltage in high voltage laboratory are measured by the proposed device, and the results are excellent.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.900-906
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• 2000

The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMl/EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is more than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHz for satisfying the international standard about an anechoic chamber for EMl/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cut corn type and cylinder type absorbers satisfying the above requirments and carried out broadband design using the equivalent material constants method.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2
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• pp.86-92
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• 2001

Various array processing techniques to identify the noise source position or bearing have been developed. Typical array processing techniques which are based on time delay between received signals at two sensors, are classified as conventional beamforming, correlation function and NAH (Near-Field Acoustic Holography) techniques which have their own characteristics with respect to application field and signal processing method. In this study, correlation function technique which could be applied for broadband noise source detection, is adopted and the effective detection technique is proposed considering the effects of source bandwidth and measurement noise correlation of noise sources. The validity of the Proposed technique is evaluated using the 3-dimensional nonlinear any which does not give 3-dimensional Position or bearing ambiguity

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.721-726
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• 2000

The remarkable progress of electronics and radio communications technology has made our life abundant. On the other hand, the countermeasure of EMC becomes more important socially according to the increased use of electromagnetic waves. It had been required that the absorbing ability of an electromagnetic wave absorber is mote than 20 dB, the bandwidth of which is required through 30 MHz to 1,000 MHB for satisfying the international standard about an anechoic chamber lot EMl/EMS measurement. From November of 1998, however, the CISPR11 has accepted the extended frequency band from 30 MHz to 18 GHz in the bandwidth of EMI measurement. In this paper, we proposed the cutting corn-shaped type satisfying the above requirements and carried out broadband design using the equivalent material constants method. Moreover, we have fabricated it and compared its characteristics with simulated one.

• Journal of the Semiconductor & Display Technology
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• v.22 no.3
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• pp.8-13
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• 2023

High bandwidth memory a core technology of the future memory semiconductor industry, is attracting attention. Temporary bonding and debonding process technology, which plays an important role in high bandwidth memory process technology, is also being studied. In this process, total thickness variation is a major factor determining wafer performance. In this study, the reliability of the equipment measuring total thickness variation is identified, and the servo motor settling, and wafer total thickness variation measurement accuracy are analyzed. As for the experimental variables, vacuum, acceleration time, and speed are changed to find the most efficient value by comparing the stabilization time. The smaller the vacuum and the larger the radius, the longer the settling time. If the radius is small, high-speed rotation performance is good, and if the radius is large, low-speed rotation performance is good. In the future, we plan to conduct an experiment to measure the entire of the wafer.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.84-90
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• 2006

With the widespread of the wireless Internet and wireless LAN, different wireless technologies such as 3G cellular networks and WLAN will cooperate to support more users and applications with higher data rate over wider areas. When a mobile node moves around in the hybrid networks, it needs to perform seamless vertical handoffs between different wireless networks to provide high performance data transmission. When an application with TCP connection in a mobile node performs a vertical handoff, TCP performance is degraded due to packet losses even though it maintains the previous TCP state information during handoff, because 3G and WLAN have different available bandwidth. In this paper, we propose a new congestion control algorithm for vertical handoff to improve the TCP performance by measuring the rough end-to-end available bandwidth and calculating the slow-start threshold. By ns-2 simulation, we show that the proposed algorithm enhances the TCP performance during vertical handoffs compared to the previous algorithms.