• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.14-19
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• 2003

In this paper, a λ/4 hair-pin resonator is proposed to reduce the size of resonators. A LTCC MLC bandpass filter is designed using the λ/4 hair-pin resonators. The electromagnetic coupling structure between two planar resonators is analysed. The equivalent circuit is derived to explain the behavior of the LTCC MLC bandpass filter using λ/4 hair-pin resonators. A design procedure is also described. The simulated and measured results of 1.8 GHz band 2-pole bandpass filter are presented.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.39-43
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• 2002

In this thesis, a λ/4 hair-pin resonator is proposed to reduce the size of resonators. A LTCC MLC bandpass filter is designed using the λ/4 hair-pin resonators. The electromagnetic coupling structure between two planar resonators is analysed. The equivalent circuit is derived to explain the behavior of the LTCC MLC bandpass filter using λ/4 hair-pin resonators. A design procedure is also described. The simulated and measured results of 2-pole bandpass filter are presented.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.171-176
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• 1997

A hair-pin shaped microstrip-line resonator and dielectric resonator for injection-locked oscillators have been designed and fabricated for the comparative studying of their performances. In general, a commonly used dielectric resonator shows lower phase noise value than hair-pin resonator in the free-running mode. In the injection-locked mode, however, a hair-pin resonator is superior to the dielectric resonator, the wider tuning range, the 22% improved locking bandwidth, the lower noise effect, the short term stability, and the higher power level. The planar structure of a hair-pin shaped microstrip-line resonator will be easily applied to monolithic microwave integrated circuits.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.530-534
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• 2002

In the thesis, For improving the Stability of VCHRO(Voltage Controlled Hair-pin Resonator Oscillator) the new structure using the parallel feedback of the second harmonic is proposed for self-phase locking effect. This module is composed of wilkinson divider, frequency doubler, directional coupler, and bandpass filter using a hair-pin resonator, which are integrated into miniaturized hybrid circuit. The module exhibits output power of 2.5 dBm at 19.5 GHz, -29.83 dBc fundamental frequency suppression and -76.52 dBc/Hz phase noise at 10 kHz offset frequency from carrier of center frequency 19.5 GHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.239-244
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• 1997

A hair-pin shaped microstrip-line resonator and a dielectric resonator for injection-locked oscillators have been designed and fabricated for the comparative studying of their characteristics. In general, a commonly used dielectric resonator shows lower phase noise value than hair-pin resonator in the free-running mode. In the injection-locked mode, however, a hair-pin resonator is superior to the dielectric resonator; the wider tuning range, the 22% improved locking bandwidth, the lower noise effect, the short term stability, and the higher power level. The planar structure of a hair-pin shaped microstrip-line resonator will be easily applied to monolithic microwave integrated circuits.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.83-89
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• 2010

In this paper, we propose a new varactor coupled line structure and design the VCO using the proposed structure. The proposed coupled line structure removes the reflected signals from the varactor diode using an added $\lambda$/4 transmission line. The frequency synthesizers are designed using the PLL technique at Ku-band. The synthesizer using the proposed coupled structure has 38 MHz frequency tuning range and -97 dBc/Hz phase noise characteristic at 100 KHz offset frequency. The measured results show improved tuning range as well as the improved phase noise characteristics compared to the conventional designs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.468-474
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• 2010

In this paper, a VCHO(Voltage Controlled Harmonic Oscillator) for K-band application has been designed and implemented. The proposed oscillator has a structure of two hair-pin resonators placed on input and output of active device. Using in/out common frequency tuning structure, the VCHO yields some advantages of the enhanced fundamental frequency suppression characteristic as well as the improved output power of second harmonic. According to implementation and measurement results, it was shown that a VCHO provides an output power of -2.41 dBm, a fundamental frequency suppression of -21.84 dBc, and phase noise of -101.44 dBc/Hz at 100 kHz offset. In addition, as for the bias voltage from 0 V to -10 V for the varactor diode, output frequency range of 10.58 MHz is obtained with a power variation of ${\pm}0.19\;dB$ over its frequency range.

• Journal of the Korea Fashion and Costume Design Association
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• v.10 no.1
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• pp.99-116
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• 2008

This study reviewed pertinent literature and examined relics of manggon(a headband worn to hold a man's topknot hair in place), donggot(a topknot pin), and chigwan(a topknot cover). Before the modernized short hair style, wearing a gat was an important custom. Therefore, manggon, which was used to hold a man's hair in place under the gat, was considered an essential part of the man's official dress code. Donggot is a pin that held the topknot hair in place. It was a must have for a married man, like the binyeo, a lod-like hairpin, for a married woman. Unlike gwanja, it had nothing to do with official rank, but materials were of a variety of materials, including jade and gold. The structure of the donggot was studied in three parts-head, neck and body. Major forms for the head include the mushroom, bean and ball. Bullet and half-cut bullet forms were also found. Forms for the neck include straight-neck and curved-neck. A neck with a belt around a double chin was also found. Forms for the body include the tetrahedron, octahedron and cylinder. The most popular form for silver and white bronze donggot heads was the mushroom, followed by bean and pile forms. Chigwan is also called chipogwan, chichoal, choalgyesogwan, noingwan and sangtugwan. In poetry it was called chichoal, and it used to be called taegogwan in the past as well. Chigwan was so small that it managed to hold a topknot. According to confucian custom in the Joseon period, by wearing chigwan, men didn't display their bare topknot even when they didn't dress up. When they went out, they wore another official hat over the chigwan.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.407-413
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• 2011

In this paper, the reduced size of broad bandpass filter with parallel coupled line structure is presented. This proposed filter can control bandwidth of narrow to broadband by adjusting the coupling coefficient. The conventional filter is operated with a narrow band. If a higher bandwidth is desired than the conventional narrow bandwidth, it is hard to realize due to the coupling coefficient between feeding line and resonator. In this paper, to overcome this limitation, a proposed bandpass filter is designed with reduced size due to SIR (Stepped Impedance Resonator), U-shaped open stub with hair-pin and vertical-type structure than conventional one, and it has characteristics of adjusting bandwidth freely as per quantity of coupling coefficient. The proposed bandpass filter that, experimental results of insertion and return losses are 0.42 dB and 24.5 dB with bandwidth of 60 % at the center frequency of 5.8 GHz, respectively.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.27-30
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• 2018

In this study, a 40 GHz band pass filter(BPF) employing a hair-pin structure has been designed, fabricated, and characterized for millimeter-wave wireless communication applications. Using the 3 dimensional(3-D) electromagnetic(EM) tool and design equations of the hairpin BPF, the BPF was desgned on the 5 mil-thick Duroid substrate(RT5880) with a relative dielectric constant (${\varepsilon}_r$) of 2.2. The tapping point (t) of the U-shape resonator in the input and output port has been determined using extracted an external Q-factor ($Q_e$). The coupling coefficients between the other resonators are calculated by adjusting the physical dimensions for the desired response of the BPF. The fabricated BPF was characterized using probing method on a probe station. Its measured center frequency(fc) and fractional BW are 41.6 GHz and 7.43 %, respectively. The measured return loss is below -10 dB at the pass band and the insertion loss is 3.87 dB. The fabricated BPF is as small as $9.1{\times}2.8mm^2$.