• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.2
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• pp.144-150
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• 2008

Recently, there has been growing interest in low loss and low dielectric constant material for LTCC application, as the frequency range for electronic devices increases. This study was designed to evaluate the effect of cordierite filler for low dielectric constant LTCC material. From the previous experiments, two glass compositions of B-Si-Al-Zn-Ba-Ca-O and B-Si-Al-Sr-Ca-O system, were chosen. Each powder of two glass compositions was sintered respectively with commercial cordierite powder in temperature range from $800^{\circ}C\;to\;900^{\circ}C$. Crystalline cordierite and glass peaks were affected only with two factors of composition and sintering temperature among various factors. With the optimized condition of two cordierite/glass compositions, obtained dielectric constant was below 5.5 and quality factor was above 1,000. Closed pore of sintered body was controled by sintering temperature and sintering time. When cordierite/glass composite with ratio of 5.5:4.5 was sintered at $900^{\circ}C$, densification was sufficient with good dielectric characteristics of ${\epsilon}_r<5.1,\;Q{\ge}1,000$. Residual fine closed pores could be reduced with control of sintering temperature and time. 3 point bending strength and chemical durability were evaluated to obtain feasibility for substrate material.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.91-97
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• 2011

In this study, we design and implement a cavity filter for the Korea T-DMB broadcasting transmitter station and repeater system. HFSS 3 dimensional field simulation tool is used for this study. T-DMB filter has to be high quality factor Q, and cavity filter is applying in T-DMB system due to high handling power. We use HFSS simulation tool for design to obtain exact resonant frequency with easy design. A cavity filter is implemented based on the simulated results, and test results are compared with simulations. Measured resonant frequency and bandwidth are 211.8MHz and 0.1MHz, and correspond with design values.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.15-20
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• 2012

In this paper, we designed and analysed K-band front-end module for digital microwave communication system receiver which improvement of dynamic range. We also suggested method of minimum amplified input signal level used to minimize noise figure of low-noise amplifier for High dynamic range. The designed modules consist of active mixer with conversions gain and PL-DRO with high stability and quality factor. The designed modules performance is that has the characteristics of over 54dB conversion gain, 1.3dB noise figure.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.73-82
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• 2005

This paper describes shock waveform synthesis methods for a shock response spectnlm over a short time interval with which intereference between parts within a test item is increased to perform a sufficient shock test for damage or malfunction which may be caused by the interference between parts, and a digital filter for obtaining a shock response history required for the shock waveform synthesis and a digital inverse filter for restoration by inversely using the digital filter. The time at which the maximax value occurs in the response history is detected in order to establish a delay time which is one of the parameters in the wavelet, on the condition that the natural frequency of SDOF system with a Q (quality factor) of 10 equals to the wavelet frequency of the zero delay wavelet input. A shock response spectrum over a short time interval and an abrupt change in the acceleration for an instant are illustrated as features of the synthesized waveform.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.249-252
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• 2003

The microwave dielectric properties of $0.7Mg_4Ta_2O_9-0.3TiO_2$ ceramics were investigated. All samples were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by X-ray Diffractor meter. According to. the X-ray diffraction patterns of the $0.7Mg_4Ta_2O_9-0.3TiO_2$ ceramics, major phase of the hexagonal $Mg_4Ta_2O_9$ were appeared. In the case of $0.7Mg_4Ta_2O_9-0.3TiO_2$ ceramics sintered at $1400^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 11.72, 126,419GHz, $-31.82ppm/^{\circ}C$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.136-139
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• 1997

In this paper, we inveatigate frequency dependance of inductance effects of FeCoB amorphous magnetic films. First, amorphous magnetic film having near zero magnetostriction is the basic composition of (Fe$_{1-x}$ / $Co_{x}$)$_{79}$Si$_2$B$_{19}$ with x=0.94, 0.95 and in order to decrease magnetio . anisotropy, the film was annealed in 28$0^{\circ}C$/30min, 40$0^{\circ}C$/30min, 40$0^{\circ}C$/1hr with near crystallization temperature under non-magnetic field. As result of investigation, in case of x=7.95 than x=0.94, we could have obtained high values, which inductance ratios in the low frequency was 488%. And Quality factor Q was under 0.7 in all sample, in case of annealed in 28$0^{\circ}C$/30min, we could have obtained highest value, which x=0.9fl is about 0.62 in 400[kHz], and in case of x=0.95 was about 0.35 in 1[MHz].z].].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.292-293
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• 2006

$ZnNb_2O_6$ ceramics were sintered under the presence of zinc-borosilicate(ZBS) glass and resultant microwave dielectric properties were investigated with a view to applying the composition to LTCC technology. The addition of 10~30 wt% ZBS glass ensured successful sintering below $900^{\circ}C$. In general, increased addition of ZBS glass increased sinterability but it decreased the dielectric properties significantly due to the formation of an excessive liquid and second phases. The sintered $ZnNb_2O_6$ ceramics at $900^{\circ}C$ with 25 wt% ZBS glass demonstrated 15.8 in dielectric constant(${\varepsilon}_r$), 5,400 in quality factor($Q{\times}f_0$), and $-98\;ppm/^{\circ}C$ in temperature coefficient of resonant frequency(${\tau}_f$).

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.325-331
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• 2003

In this paper, we designed a spiral inductor and voltage controlled oscillator with the negative resistor for the bluetooth receiver by using 0.25$\mu\textrm{m}$ 1-poly 5-metal CMOS n-well process. The proposed inductor, which applies multi layer metal structure, is a structure that decreases resistance value by increasing he metal thickness. As the resistance value decreases, the quality factor Q has improved. Also, voltage-controlled oscillator is designed applying 1 port negative resistance, and changes its oscillating frequency by varying outside capacitor values. The simulation results show that oscillating frequency is 2.33~2.58GHz changing from 2pF to 14pF, and the oscillator has oscillating power over 0dBm.

• Journal of Dairy Science and Biotechnology
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• v.41 no.1
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• pp.34-43
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• 2023

Hydrolysis of whey-derived proteins using lactic acid bacteria (LAB) utilizes the mass culture method and fermentation of LAB to produce effective bioactive peptides. Whey protein has the biological potential of its precursors, but the active fragments may not be released depending on the hydrolysis method. As an alternative to these problems, the nutritional and bioactive functionality of the hydrolysis method have been reported to be improved using LAB for whey protein. Peptide fractions were obtained using a sample fast protein liquid chromatography device. Antioxidant activity was verified for each of the five fractions obtained. In vitro cell experiments showed no cytotoxicity and inhibited nitric oxide production. Cytokine (IL [interleukin]-1α, IL-6, tumor necrosis factor-α) production was significantly lower than that of lipopolysaccharides (+). As a result of checking the amino acid content ratio of the fractions selected through the AccQ-Tag system, 17 types of amino acids were identified, and the content of isoleucine, an essential amino acid, was the highest. These properties show their applicability for the production of functional products utilizing dietary supplements and milk. It can be presented as an efficient method in terms of product functionality in the production of uniform-quality whey-derived peptides.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1726-1728
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• 1999

Dielectric and piezoelectric properties of xPb$(Al_{1/2}Ta_{1/2})O_3$-(1-x)Pb$(Zro_{0.52}Ti_{0.48})O_3$ system were investigated. The highest density of $7.80g/cm^3$ for PAT-PZT ceramics of 5mol% PAT was obtained. The relative permittivity of PAT-PZT ceramics of 5mol% PAT was 1.642 at room temperature. The maximum value of electromechanical coupling factor $k_p$ of 55% and $k_t$ of 33% were obtained at the composition of 5mol% PAT. The grain sizes were reduced by increasing the amount of PAT, however mechanical quality factor$(Q_m)$ had a minimum value of 44 at the composition of 5mol% PAT.