• Steel and Composite Structures
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• v.49 no.5
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• pp.533-546
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• 2023

Cost-effective solutions provided by composite construction are gaining popularity which, in turn, promotes the appearance on the market of new types of composite sections that allow not only to take advantage of the synergy of steel and concrete working together at room temperature, but also to improve their behaviour at high temperatures. When combined with high performance materials, significant load-bearing capacities can be achieved even with reduced cross-sectional dimensions. Steel-reinforced concrete-filled steel tubular (SR-CFST) columns are one of these innovative composite sections, where an open steel profile is embedded into a CFST section. Besides the renowned benefits of these typologies at room temperature, the fire protection offered by the surrounding concrete to the inner steel profile, gives them an enhanced fire performance which delays its loss of mechanical capacity in a fire scenario. The experimental evidence on the fire behaviour of SR-CFST columns is still scarce, particularly when combined with high performance materials. However, it is being much needed for the development of specific design provisions that consider the use of the inner steel profile in CFST columns. In this work, a new experimental program on the thermo-mechanical behaviour of SR-CFST columns is presented to extend the available experimental database. Ten SR-CFST stub columns, with circular and square geometries, combining high strength steel and concrete were tested. It was seen that the circular specimens reached higher failure times than the square columns, with the failure time increasing both when high strength steel was used at the embedded steel profile and high strength concrete was used as infill. Finally, different proposals for the reduction coefficients of high performance materials were assessed in the prediction of the cross-sectional fire resistance of the SR-CFST columns.

• ETRI Journal
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• v.35 no.1
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• pp.1-6
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• 2013

In this paper, we present an implemented serial 40-Gb/s receiver optical subassembly (ROSA) module by employing a proposed TO-CAN package and flexible printed circuit board (FPCB). The TO-CAN package employs an L-shaped metal support to provide a straight line signal path between the TO-CAN package and the FPCB. In addition, the FPCB incorporates a signal line with an open stub to alleviate signal distortion owing to an impedance mismatch generated from the soldering pad attached to the main circuit board. The receiver sensitivity of the ROSA module measures below -9 dBm for 40 Gb/s at an extinction ratio of 7 dB and a bit error rate of $10^{-12}$.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.88-91
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• 2000

An MMIC oscillator operating at the 24.55 GHz has been designed using 0.2 ${\mu}{\textrm}{m}$AlGaAs/InGaAs/GaAs Pseudomorphic HEMT technology. The active device used in the oscillator design has a 0.2 ${\mu}{\textrm}{m}$ gate length PHEMT with 4$\times$80 ${\mu}{\textrm}{m}$ gate width. We obtained 4.08 dB of S$_{21}$ gain and 317 mS/mm of transconductance, and extrapolated unit current gain cut-off frequency (f$_{T}$) and maximum oscillation frequency (fmax) were 62 GHz and 120 GHz, respectively. The circuit are based on a series feedback and negative resistance topology. Microstrip line open stub is used to terminating. The oscillator circuits has designed for delivering maximum power to load and conjugated matching. The simulated small signal negative resistance was 50 Ω. We obtained 1.002 of loop gain and 0.0005$^{\circ}$angle from the simulation by HP libra 6.1. The layout for oscillator is 1.2$\times$1.8 $\textrm{mm}^2$.>.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.153-160
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• 2005

In this paper, the novel microwave oscillator incorporating a planar cavity resonator(PCR) is presented to reduce the phase noise of the oscillator in a planar environment. Compared to the conventional planar( $\lambda$/4 open stub resonator), the phase noise is improved about 16 dBc/Hz @100 kHz. The design of the oscillator is based on a reflection type configuration using the low 1/f SiGe HBT transistor(LPT16ED). The output power is measured 2.76 dBm at 12.5 GHz. In this paper, the oscillator used to the PCR can be expected to provide a solution for low phase noise oscillator in microwave circuits.

• Journal of Navigation and Port Research
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• v.30 no.7
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• pp.607-610
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• 2006

A new compact microstrip low-pass filter and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.79-84
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• 2006

A novel design of compact low-pass filter based on microstrip structure and its equivalent-circuit model are developed. The philosophy of the structure behind this novel microstrip low-pass filter is simple as it is composed of a pair of symmetrical parallel coupled-line and an open-stub. With this configuration, a finite attenuation pole near the stopband cutoff frequency is available and adjustable by simply tuning the circuit parameters. Furthermore, the rejection bandwidth of this type of low-pass filter can be extended. In order to validate the feasibility of the proposed design method, a low-pass filter based on a microstrip structure is designed, fabricated, and measured. Experimental results agree very well with the simulation and analytical results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.225-228
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• 2000

In this paper, the design for a low noise amplifier with the EM simulation is presented. The ATF36077 pHEMT device is applied to design LNA for U-NII frequency band (5 GHz ～ 6 GHz). The matching networks have been designed by the only open ended stub in order to reduce parasitic effects generated from a via structure. Through EM simulator, the simulation result shows that the linear gain (@5.5 GHz) is over 10 dB, input return loss and output return loss (@ 5.5 GHz) are a below 10 dB respectively, and the 3rd order intercept point is about 17 dBm.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.361-366
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• 2016

This paper presents an arbitrary impedance transformer with unequal split, based on S- to admittance parameter conversion. When compared even/ odd- mode analysis, the parameter conversion design method constitutes a simple design method to include phase delay information and arbitrary port impedances and asymmetrical configurations. To validate this design method, we designed a 50 to $12.5{\Omega}$ impedance transformer with a 3:1 unequal power split, at an operating frequency of 1 GHz. To implement the proposed impedance transformer, the low impedance transmission lines of calculated result are fabricated by the transmission line connected shunt open stub. Good experimental performances were obtained, in full agreement with simulated results.

• Steel and Composite Structures
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• v.23 no.1
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• pp.115-130
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• 2017

A new type of moment-resisting bolted connection was developed for use in composite steel- concrete construction to connect composite open section steel beams to concrete filled steel square tubular columns. The connection was made possible using anchored blind bolts along with two through bolts. It was designed to act compositely with the in-situ reinforced concrete slab to achieve an enhanced stiffness and strength. The developed connection was incorporated in the design of a medium rise (five storey) commercial building which was located in low to medium seismicity regions. The lateral load resisting system for the design building consisted of moment resisting frames in two directions. A major full scale test on a sub-assembly of a perimeter moment-resisting frame of the model building was conducted to study the system behaviour incorporating the proposed connection. The behaviour of the proposed connection and its interaction with the floor slab under cyclic loading representing the earthquake events with return periods of 500 years and 2500 years was investigated. The proposed connection was categorized as semi rigid for unbraced frames based on the classification method presented in Eurocode 3. Furthermore, the proposed connection, composite with the floor slab, successfully provided adequate lateral load resistance for the model building.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.411-415
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• 2003

In this paper, a reflector type frequency doubler for local oscillator at 24GHz is designed and fabricated with ne71300-N MESFET. Optimum source and load impedances are decided through a multiharmonic load pull simulation technique. A conversion gain ran be improved using the reflector and fundamental and third harmonics are well suppressed with open stub of λ/4 length. Measured results show output power at 0dBm of input power is -3.776dBm, conversion gain 0.736dB, harmonic suppression 41.064dBc, respectively.