• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2002.05a
• /
• pp.134-137
• /
• 2002

A new LTCC material in the $PbWO_4-TiO_2-B_2O_3-CuO$ system was developed. The developed material can be sintered at $850^{\circ}C$ and its dielectric properties are $\varepsilon_r=20-25, Q\timesf_o=30000~50000GHz$ , and $\tau_f=0.2~30ppm/^{\circ}C$, depending on the components moi ratio. Due to its low sintering temperature and microwave dielectric properties, the developed material can be used as a LTCC substrate for fabrication of multilayered microwave communication module set. In present study, using this material, tape casting condition was established. With this processing condition, a T-resonator was fabricated and its electrical properties were examined. Also, a 2-Pole band pass filter was fabricated and its frequency characteristics were compared with simulation results.

• Progress in Superconductivity and Cryogenics
• /
• v.22 no.4
• /
• pp.10-13
• /
• 2020

High-quality superconducting coplanar waveguide (SCPW) resonators are crucial for developing superconducting quantum information devices and sensors. We designed quarter-wavelength SCPW resonators and fabricated the SCPW resonators using Nb thin film. The resonant characteristics were measured at T = 4.2 K, revealing the intrinsic quality factor and the coupling quality factor to be Qi = 4,784 and Qc = 17, 980, respectively. Our design and fabrication techniques would be very useful to develop a gate-tunable superconducting qubit based on the semiconductor nanostructures.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.1
• /
• pp.62-71
• /
• 2008

Swirl injector with adjustable backhole length was analyzed to suppress high-frequency combustion instability in Liquid Rocket Engines. In order to analyze the effect of swirl injector as an acoustic absorber, swirl injector was regarded as a quarter-wave resonator and its damping capacity is verified in atmospheric temperature. Experiments were carried out with copied tubes on air core because the interior air core volume of injector has a direct effect on damping. From the experimental data, it is proved that increasing the number of injectors mounted at each anti-node point can increase acoustic damping effect. Also, when tuned injectors at 1L, 1T, 1L1T modes simultaneously are installed at each anti-node point of model chamber, the damping effect of tuned injectors with multi modes agree well with it of tuned injectors with single mode.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.1
• /
• pp.20-26
• /
• 2003

This paper presents hairpin-comb bandpass filter using ground aperture. Hairpin-comb resonator maintains the weak coupling though the space between two resonators is very small. This has the good merit that the entire filter size is small for narrowband bandpass filter. The coupling between two hairpin-comb resonators so very weak that can't be applicable to general microstrip. We compensate the coupling by using ground aperture. It makes the hairpin-comb filter possible that can be applicable to general microstrip. Also it has the good merit which adjusts the bandwidth by changing the size of aperture without changing the space. In this paper, we fabricate the bandpass filter, which has 1.78 GHz center frequency and 62 MHz (3.5%) fractional bandwidth.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2001.10a
• /
• pp.215-219
• /
• 2001

The resonators made of piezoelectric crystals such as a quartz crystal are widely used. Their frequency-temperature characteristics are of primary importance for their applications to the frequency control devices. The characteristics estimation is useful for determining their design parameters. In the present paper, several types of resonators are numerically analyzed. The numerical solutions are made using 3-D Finite Element Modeling, and the results are compared with the theoretical values whenever they are available. To demonstrate the validity of the present numerical approach, the application is made to the analysis of the plates with some well-established cutting angles. For the resonator stable with temperature change, the cutting angle is important in which the temperature coefficient of the first order is chosen to be zero. The rotated Y-cut plates in thickness-shear mode are considered. The equivalent circuit representation is often used fur describing the characteristics at the electrical terminals which enables the circuit analysis including the effect of temperature change by using the circuit simulators. The equivalent circuit parameters are obtained by fitting the admittance-frequency curve from the finite element analysis.

• Phonetics and Speech Sciences
• /
• v.9 no.1
• /
• pp.49-53
• /
• 2017

Formant frequencies depend on the position of tongue, the shape of lips, and larynx. In the auditory system, the external ear canal is an open-end resonator, which can modify the voice characteristics. This study investigates the effect of the real ear on formant frequencies. Fifteen subjects ranging from 22 to 30 years of age participated in the study. This study employed three corner vowels: the low central vowel /a/, the high front vowel /i/, and the high back vowel /u/. For this study, the voice of a well-educated undergraduate who majored in speech-language pathology, was recorded with a high performance condenser microphone placed in the upper pinna and in the ear canal. Paired t-test showed that there were significant difference in the formant frequencies of F1, F2, F3, and F4 between the free field and the real ear. For /a/, all formant frequencies decreased significantly in the real ear. For /i/, F2 increased and F3 and F4 decreased. For /u/, F1 and F2 increased, but F3 and F4 decreased. It seems that these voice modifications in the real ear contribute to interpreting voice quality and understanding speech, timbre, and individual characteristics, which are influenced by the shape of the outer ear and external ear canal in such a way that formant frequencies become centralized in the vowel space.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.760-761
• /
• 2013

본 논문은 차량 추돌 예방 레이더용 24GHz 전압제어발진기를 제안한다. 이러한 회로는 TSMC $0.13{\mu}m$ 혼성신호/고주파 CMOS 공정($f_T/f_{MAX}=120/140GHz$)으로 설계되어 있다. 이러한 회로는 스위치형 공진기 (switched resonator)의 기본 구조를 지닌 24GHz 주파수 대역을 사용할 수 있도록 CMOS LC 튜닝 회로를 포함하고 있다. 특히 전체 칩 면적을 줄이기 위해 수동형 인덕터 대신 능동형 인덕터부를 사용하였다. 본 연구에서 개발한 발진기는 전체 튜닝 범위에 대해 24GHz에서 8%의 측정결과를 보였으며, 600kHz 오프셋에서 24GHz에 대해 약 -89dBc/Hz의 우수한 위상 잡음 특성을 보였다.

• Applied Science and Convergence Technology
• /
• v.24 no.6
• /
• pp.250-253
• /
• 2015

High contrast grating (HCG) is the structure made up of the sub-wavelength grating of high-index and the surrounding layer of low-index, which reveals high contrast between two materials. Its advantages include high reflectivity over a broad bandwidth, polarization and wavelength selectivity, optical high-Q resonator, and phase modulation. In this work, the HCG structure comprising of indium tin oxide (ITO) and Silicon (Si), for the surrounding layer and the grating layer respectively, was studied. Its theoretical model was established, and transmittance, phase and optical behavior were calculated by rigorous coupled-wave analysis and finite element method. Furthermore, the established structure was fabricated to validate its feasibility. The fabricated structure shows the focusing capability whose length is about $10{\mu}m$, and the feasibility of the structure was demonstrated. It is also meaningful that ITO layer can contribute to the fabrication of the HCG structure, leading to enable the structure to be electrical-driven.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.10a
• /
• pp.702-703
• /
• 2013

본 논문은 차량 추돌 예방 레이더용 24GHz 전압제어발진기를 제안한다. 이러한 회로는 TSMC $0.13{\mu}m$ 혼성신호/고주파 CMOS 공정($f_T/f_{MAX}=120/140GHz$)으로 설계되어 있다. 이러한 회로는 스위치형 공진기 (switched resonator)의 기본 구조를 지닌 24GHz 주파수 대역을 사용할 수 있도록 CMOS LC 튜닝 회로를 포함하고 있다. 특히 전체 칩 면적을 줄이기 위해 수동형 인덕터 대신 능동형 인덕터부를 사용하였다. 본 연구에서 개발한 발진기는 전체 튜닝 범위에 대해 24GHz에서 8%의 측정 결과를 보였으며, 600kHz 오프셋에서 24GHz에 대해 약 -89dBc/Hz의 우수한 위상 잡음 특성을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.9
• /
• pp.2362-2372
• /
• 1996

This paper deals with the design and development of an Injection-Locking Coupled Oscillators(ILCO), which functions like phase-shifter in the Active Intergrated Phased Array Antenna(AIPAA). This linear array 2-element ILCO consists of two Injection Locking Hair-pin Resonator Oscillators(ILHRO) and an unilateral amplifier. The first and second elements of the ILCO have same frequency tuning range but locking bandwidths of 11.5MHz and 14MHz respectively. A phase shift of .DELTA..PHI.=158.4.deg.(-78.0.deg. to 80.4.deg.) could be obtained inthe second element of ILCO when the first elementof the ILCO was in the reference locking mode(.DELTA..PHI.=0.deg.). When the ILCO is applied to the AIPAA, the predicted beam scanning angle value will be 38.4.deg.. Each ILCO gives good frequency stability and lower AM, FM, and PM noise charactheristics in the mutual coupling lockingmode. The ILCO can not only play a part as the phase shifter for the AIPAA but it can also be usedas the power combining device in the mm-wave frequency range and as a part of a T/R MMIC module.