• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1115-1121
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• 2017

In order to obtain high thrust at the beginning of the flight, the solid rocket motor with large initial burning surface area was designed and tested. From the static firing test, lower initial thrust was obtained compared with the expected thrust based on the internal ballistic prediction due to the negative erosive burning effect which reduced the burning rate estimated by APN Law. In addition, the radial mode combustion instability was observed with 8 fins grain configuration. This instability was removed after the odd number of fins were used.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.10-16
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• 2024

Microstrip directional couplers using microstrip lines do not have good directivity characteristics because the dielectric constant of the substrate is different from that of air. To solve this problem, a compensation capacitor is sometimes attached between the coupling lines to improve directivity. This paper proposes a directional coupler with high directivity using interdigital capacitors implemented with transmission lines instead of lumped capacitors. The directional coupler designed and fabricated using the proposed method showed a coupling factor of 20 dB and a directivity of higher than 30 dB at 2.14 GHz. This directional coupler can be used as two directional couplers because it has two coupling ports and two isolated ports.

• Journal of electromagnetic engineering and science
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• v.3 no.2
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• pp.126-132
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• 2003

In this paper, a coupled-line type waveguide bandpass filter is newly proposed. The proposed bandpass filter configuration consists of magnetically coupled waveguide cavities. In order to show the background of the proposed waveguide bandpass filter, the general coupled line TEM bandpass filter theory, which means the coupled line filter with arbitrary coupled line length and impedance level, will be briefly introduced. Calculations for the even- and odd-mode wave impedance of a coupled line waveguide structure are achieved based on the normalized impedance concept for a broad-side coupled waveguides by using vector finite element method(VFEM) calculation. Measured result of an implemented coupled-line type waveguide filter is presented.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.280-285
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• 2004

In this paper, a 9-bit analog-to-digital converter (ADC) is designed for optical disk drive (ODD) servo applications. In the ADC, the circuit technique to increase the operating range of the sample-and-hold amplifier is proposed, which can process the wide-varying input common-mode range. The algorithmic ADC structure is chosen so that the area can be significantly reduced, which is suitable for SoC integration. The ADC is fabricated in a 0.18-$\mu\textrm{m} $ CMOS 1P5M technology. Measurement results of the ADC show that SNDR is 51.5dB for the sampling rate of 6.5MS/s. The power dissipation is 36.3mW for a single supply voltage of 3.3V.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2046-2048
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• 2004

In this paper, we have proposed a novel omnidirectional power divider/combiner configuration. By using the even- and odd- mode analysis. we analyse the proposed power divider/combiner circuit. In order to show the validity of the presented power divider/combiner circuit. We have designed and implemented the proposed circuit of the center frequency of 2.3GHz.

• ETRI Journal
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• v.35 no.1
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• pp.150-153
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• 2013

In this letter, a compact and fully printed composite right- and left-handed (CRLH) dual-band power divider is proposed. The branches of the conventional Wilkinson power divider are replaced by subwavelength CRLH phase-shift lines having $+90^{\circ}$ for one frequency and $-90^{\circ}$ for another frequency for dual-band and miniaturization performance. Equations are derived for the even- and odd-mode analysis combined with the dual-band CRLH circuit. A PCS and a WLAN band are chosen as the test case and the circuit approach agrees with the CAD simulation and the measurement. Additionally, the CRLH property is shown with the dispersion diagram and the eightfold size reduction is noted.

• ETRI Journal
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• v.37 no.1
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• pp.61-65
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• 2015

In this paper, a novel filtering power divider with external isolation resistors is presented. The proposed power divider can be considered as an integration of a bandpass filter and a Gysel power divider. Based on the circuit topology, a high-order filtering power divider can be easily realized. Odd- and even-mode models are employed to analyze the filtering and power splitting functions. For demonstration, a third-order filtering power divider operating at 1.5 GHz is designed and implemented. The measured results exhibit an isolation between the output ports that is better than 20 dB at around the center frequency.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.387-390
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• 1998

We propose comb-line filter using SIR(Stepped Impedance Resonator) with two transmission line. The coupling structure of the filter is double coupled line where two coupled lines are linked with cascade. We find out the inverter function of the filter. using even and odd mode impedance. The merits of the filter are that first, we can design transmission zero point at any frequency that we wanted without using lumped elements : chip capacitors and inductors. Second, we can design small size filters. To validate the inverter function of the filter with double coupled line we designed and fabricated two-pole band pass filter with the proposed filter structure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.116-119
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• 2010

In this work, we presented the characterization of 3 dB branch type directional couplers by using High-Tc superconducting thin films. To do this, we deposited YBCO superconducting thin films on MgO substrates by using rf-magnetron sputtering techniques. The designed center frequency was 408 MHz and the designed passband was 20 MHz. Also we designed 3 dB Power difference and $90^{\circ}$ of phase difference between port 3 and port 4. The even and odd mode analysis were used to characterize our directional couplers and em Sonnet (full wave analysis program) was utilized to the optimum design. We reported experimental results, including a center frequency, passband, half power characteristics and phase differences. We confirmed that experimental results were in good agreements with characterization by using full wave analysis program.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.334-338
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• 2009

In this paper, We report the miniaturization of superconducting microwave power dividers based on lumped element equivalent circuits. To do this, we analyzed a conventional branch-type power divider by using an ABCD matrix under even and odd mode excitation. Then, we calculated each lumped element impedance throughout this analysis of a transmission line matrix. Also we simulated our equivalent circuits made of lumped elements by using a full wave analysis, em Sonnet. Our deign of microwave power divider based on simulated results was fabricated on high-$T_c$ superconducting thin films deposited on MgO substrate. Experimental results were reported in terms of bandwidth, center frequency, and phase difference between $S_{21}$ and $S_{31}$. We confirm that our design will be useful in the future microwave power systum.