• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2267-2272
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• 2009

The six-port direct conversion receiver front-end that is comprised of a carrier recovery and a phase shifter, which gets the same structure with six-port phase correlator using the multi-layer coupled line, was designed and fabricated in this paper. The six-port element that is comprised of the power divider and the hybrid coupler is designed by multi-layer coupled line structure. The multi-coupled structure is utilized as the basic structure in receiver phase correlator, carrier recovery circuit and phase shifter. The receiver front-end with the same multi-layer coupled line structure for the receiver elements shows the simple structure and no difficulty in integration. The fabricated multi-layer coupled six-port receiver front-end re-generates the carrier signal with a constant phase and demodulates the PSK transmission signal.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.972-975
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• 1999

Until now, all of the port goods are transported by container transporter driven manually but recently there are a lot of researches about unmanned vehicle driven automatically. In this paper, we present a design of the TDOF PID controller using a hybrid schematic algorithm to control steering system. We used the ES and SA algorithms to construct hybrid tuning algorithm. Then the computer simulation shows that our proposed controller has better Performances than the other one.

• Journal of Power System Engineering
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• v.14 no.2
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• pp.12-15
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• 2010

It is requested to shorten the starting duration for idle stop function equipped cars without harmful effects on the environment. Higher cranking speeds can be achieved with high torque starter. The object of this study is to develope the high torque starter and evaluate its effect on the exhaust emissions. The test was conducted on a 1.5 L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine. Engine out emissions such as HC, CO, $CO_2$, and the excess air ratios, lambda were measured using MEXA-554JK. The result showed that a high torque starter, HTS-II shortened the starting duration and reduced engine out emissions of HC, CO and improved starting performance with larger excess air ratio than that of the original starter, Org. S and a high torque starter, HTS-I.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.52-59
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• 1996

This paper presents a monopulse feed structure with low sidelobe monopulse pattern, which consists of a E-plane corrugated horn and a unfiorm pick-up aperture power divider. Tfhe design methods and epxerimental resutls of the E-plane corrugated feeder are described. Modified hybrid mode analysis and GSM (generalized scattering matrix) methods are introduced to design the E-plane corrugated feed horns. The 24-port corrugated feeder is designed using modified hybrid mode analysis initially and verified using GSM methods. Measurement results show that this feeder has low return loss and sidelobe level at sum and difference channel, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.4
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• pp.325-334
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• 1987

Microwave integrated circuit phase shifters have undergone remarkable development to satisfy the fast and precise phase control requirements for phased array antennas. It is shown how relection type phase shift circuits using PIN diode can be analyzed and implemented so as to derve design equations for any phase shift. The reflection properties are achieved by the use of an impedance transforming two-port network and the virtual matching impedance method. Experimental and theoretical performance of 2-bit hybrid phase shifter designed by this method are found to be in good agreement for each bit.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.4
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• pp.184-190
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• 2022

In an attempt to apply hybrid rocket to the RATO (Rocket-Assisted Take Off) system, combustion characteristics of the non-circular grain were figured out in this study. Having larger combustion area, it was reconfirmed that the non-circular grain has advantages over regression rate, characteristic velocity and chamber pressure in which all gave higher values. Experiments were performed to understand the effect of the non-circular grain geometry over time where local regression rates depending on grain location were analyzed. It was found that the regression rate of five distinct locations were different. Partial conclusion driven was that these differences are due to the heat transfer caused by dissimilar distances from the flame layer. Besides, as combustion duration increased, the fuel port became circular, and the regression rate converged to a single value over the whole grain.

• Journal of the Korean Institute of Navigation
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• v.23 no.2
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• pp.11-22
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• 1999

This paper is concerned with the development of a tractable model to assist liner shipping companies in the decision-making of empty container repositioning and leasing. A hybrid methodology is presented which properly accounts for the specific characteristics of empty container management. For this mathematical models are developed based on dynamic network models, covering both land and marine segment. Then a stochastic method is presented to deal with the uncertainty of the future demand and supply. Especially, the concept of opportunity cost has been introduced in order to explain interactions between the variation of the future demand and supply and the stock level at each depot.

• Journal of the Korean Institute of Navigation
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• v.20 no.4
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• pp.99-109
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• 1996

Though median filter is used for removing noise and smoothing image. But, the result of it has distortion around edge. And then, this paper proposes new noise removing algorithm by recursive morphological processing. Basic operation is same each other, but there is some different processing method between recursive morphology and general morphology theory. This recursive morphological filter can be viewed as the weighted order static filter, and then it has a weighted SE(structuring element). Especially using this algorithm to remove the 10% gaussian noise, this paper confirmed that PSNR is improved about 0.642~1.5757 db reserving edge well better than the results of the traditional median filter.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.73-79
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• 2015

Enhanced bandwidths of the GPS microstrip patch antennas applied by a Wilkinson power divider and a quadrature hybrid were compared. The square patch was designed, and fed by the two port probes for the circuit application. The Wilkinson power divider and quadrature hybrid circuit were designed, and applied to the patch antenna. The designed patch and two circuits were implemented on the FR4 board, and combined together. The measurement of the bandwidth within a voltage standing wave ratio (VSWR) of 2: 1 were 36.5% (1,200~1,775 MHz) in the case of the Wilkinson power divider and 29.84% (1,230~1,700 MHz) in the case of the quadrature hybrid. Axial ratios (AR) in 3dB were 17.14% bandwidth (1,360~1,630 MHz) and 15.87% bandwidth (1,400~1,650 MHz), respectively. The application of the Wilkinson power divider is wider than that of the quadrature hybrid. The peak gains in the anechoic chamber at the GPS center frequency were measured as 2.84 dBi and 2.75 dBi, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.765-768
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• 2015

In this paper, two ports feeding a microstrip patch antenna using a quadrature hybrid circuit was proposed to enhance the bandwidth for the global positioning system(GPS). The square patch was designed, and the probe feeding was applied. The quadrature hybrid chip circuit for two-port feeding was designed, and output ports that have a 90-degree phase difference feed to the patch antenna. The designed patch and quadrature hybrid circuit were implemented on an FR4 board, and were combined. The measurement of the bandwidth within a voltage standing wave ratio(VSWR) of 2: 1 and axial ratio(AR) in 3dB were 29 %BW(1,230~1,700 MHz) and 15.87 %BW(1,400~1,650 MHz), respectively. The peak gain at the GPS center frequency was measured at 2.75 dBi in an anechoic chamber.