• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.62-66
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• 2003

Novel coupled line phase shifters and its equivalent phase delay line for compact broadband phased array antennas are proposed. These phase control circuits are designed to be less complex, small size and to use a less number of active devices. The phase shifter is able to control a 120$^{\circ}$ phase shift continuously, and the phase delay line for a reference phase has a fixed 60$^{\circ}$ shifted phase. Both have the low phase error of less than $\pm$3.5$^{\circ}$ and the low gain variations of less than 1 ㏈ within the 300 MHz bandwidth. These proposed circuits are adequate to form the efficient beam-forming networks with compactness, broadband, less complexity, and low cost.

• Journal of IKEEE
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• v.24 no.4
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• pp.1028-1033
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• 2020

The existing in-band interference reduction method recommends the physical separation distance between wireless devices and interference signals, and the interference can be suppressed through the separation distance. If the in-band interference signals can be reduced in a wireless device, a margin can be given to the physical separation distance. Since there is an effect of extending the receiver dynamic range of receivers, it is highly useful for interference reduction and improvement method. In this paper, the structure of an in-band analog IRM(Interference Reduction Module) is proposed and the design and implementation of the proposed analog IRM are described. To design an analog IRM, the interference reduction performance according to the delay mismatch, phase error and the number of delay lines that affect the performance of the analog IRM was simulated. The proposed analog IRM composed of 16 delay lines was implemented and the implemented IRM has the interference reduction performance of about 10dB for a 5G(NR-FR1-TM-1.1) signal having a 40MHz bandwidth at a center frequency of 3.32GHz. The analog IRM proposed in this paper can be used as an in-band interference canceller.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.156-164
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• 2014

In a delay line type of a time-to-digital converter implemented in Field Programmable Gate Array, the timing accuracy decreases for a longer carry chain. In this paper, we propose a structure that has a multi-phase clock and a state machine to check metastability; this would reduce the required length of the carry chain with the same time resolution. To reduce the errors caused by the time difference in the four delay lines associated with a four-phase clock, the proposed TDC generates a single input pulse from four phase clocks and uses a single delay line. Moreover, the state machine is designed to find the phase clock that is used to generate the single input pulse and determine the metastable state without a synchronizer. With the measurement range of 1 ms, the measured resolution was 22 ps, and the non-linearity was 25 ps.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.61-64
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• 2017

A phase shifter is one of the key components that change the phase of an individual antenna in millimeter-wave phased array system. This paper presents a low-loss phase shifter design with two parallel 2-state amplifiers. To get the same gain of $0^{\circ}/180^{\circ}$ each state, delay lines are in the middle of each stage of the 2-Stage amplifiers. Normally, when adding AMPs in parallel, a power combiner/divider such as Wilkinson Power Combiner/Divider is added, but they are directly connected because it can cause added losses in silicon wafer. The measured data shows 12dB gain and 174-degree phase difference at 5GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.147-151
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• 2009

A wideband correlator, with 45% relative bandwidth is proposed at the frequency range of 3.1-5.1GHz. The structures of the correlator components such as the delay line and the Wilkinson power divider are designed to be realized in transmission line form using the Agilent's Advanced Design System (ADS). The correlator made by using three unique wideband 3-dB couplers, rat-race coupler and one 3-dB wilkinson power divider to reach the required bandwidth. The insertion loss, amplitude imbalance and phase imbalance between ports are presented. The proposed correlator makes compact size better than correlator of conventional structure.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.38-44
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• 1999

This paper primarily directed toward analyzing the frequency response in hydraulic pipe lines with a small diameter. The exact solution to the frequency response is obtained by using the complicated transfer function. The discrepancy with the exact and the approximate is small so the approximation solution is adopted to compare the experimental results with the theoretical analysis. In this experiment the input frequency was generated by the frequency generator with the ball valve and speed controller. In order to compare the theoretical were forms with the experimental ones the trace obtained from the oscilloscope is photographed, The diameter the length of lines and input pressure amplitude are varied to investigate their effects,. the experiment results show that th values of dimensionless parameter are very affected to the phase delay and guide response time in the design of pressure manifold to measure the pressure of hydraulic pipelines.

• Journal of Sensor Science and Technology
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• v.16 no.5
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• pp.349-354
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• 2007

This paper presents characteristics of surface acoustic wave (SAW) gas sensor for detecting volatile gases such as ethanol gas by measuring the phase shift of output signal. A delay-line with a center frequency of 400 MHz was fabricated on $128^{\circ}$ Y-Z $LiNbO_{3}$ substrates. Experimental results, which showed the phase change of the output signal under the absorption of volatile gas on sensor surface, were presented. The sensitivities of SAW delay lines coated with polyurethane films were greatly increased compared to those for uncoated devices. This SAW gas sensor system may be well suited for a high sensitivity electronic nose system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.364-364
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• 2007

This paper presents characteristics of surface acoustic wave (SAW) gas sensor for detecting volatile gases such as ethanol gas by measuring phase shift of output signal. A delay-line with a center frequency of 400MHz was fabricated on 128o Y-Z $LiNbO_3$ substrates. Experimental results, which show the phase change of output signal under the absorption of volatile gas on sensor surface, were presented. The sensitivities of SAW delay lines coated with polyurethane films are greatly increased compared to those for uncoated devices. This SAW gas sensor system may be well suited for a high sensitivity electronic nose system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2027-2034
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• 2008

There are concerns on possible health effects from exposure to electromagnetic fields. One reflection of this concerns is the considerable controversy, delay, and cost increases involved in the construction of power lines and facilities. To cope with such challenges, in this paper we investigated magnetic fields reduction techniques such as general compaction, in' span compaction, cruciform, vertical, 3 way splits phase, and 4way splits phase. As results, we found general compaction and 4 way splits phase could reduce magnetic fields up to 90%, while cruciform, vertical, and 3 way splits phase gave lower reduction rates of 30% because these configurations were similar to a current type of low reactance arrangement. We also knew 1 spacer in span compaction was appropriate in Korea in view of effectiveness and economy.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.795-803
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• 2015

Autoreclosure provides a means of improving power transmitting ability and system stability. Conventional reclosure adopts the fixed dead time interval strategy, where the reclosure is activated after a time delay to restore the system to normal as quickly as possible without regard to the system conditions. However, these simple techniques cannot provide optimal operating performance. This paper presents an adaptive autoreclosure algorithm including variable dead time, optimal reclosure, phase-by-phase reclosure and emergency extended equal-area criterion (EEEAC) algorithm in order to improve system stability. The reclosure algorithm performs the operations that are attuned to the power system conditions. The proposed adaptive reclosure algorithm is verified and tested using ATP/EMTP MODELS, and the simulation results show that the system oscillations are reduced and the transient stability is enhanced by employing the proposed adaptive reclosure algorithm.