• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.11
• /
• pp.2512-2520
• /
• 2013

In this paper, the T-SRR (Triple Split Ring Resonator) using MNG (mu-Negative) meta-material adapted in a low-loss bandpass filter with 3-stages is suggested. The size of the T-SRR in the proposed bandpass filter with low dielectric constant PCB can be easily controlled. And the ${\lambda}/4$ transmission line theory is applied. The proposed T-SRR and filter have the center frequency of 10 GHz with QL value of 184 for military-satellite communication system in I band. The experimental results of the filter show that the insertion and return losses are 1.44 dB and 17.3 dB with bandwidth of 10 %, respectively. The proposed filter will be redesigned by IPD material etc. should be placed here. These instructions give you guidelines for preparing papers for JICCE.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.14 no.6
• /
• pp.457-465
• /
• 2009

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle compared to other secondary batteries. In particular, high demand for lithium batteries is expected for electric cars. In case of lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below the level of making it impossible to crank. Therefore, accurate information about state of charge (SOC) becomes an essential element for reliable driving. In this paper, a new method of estimating the SOC of lithium polymer batteries by using AC impedance is proposed. In the proposed method, parameters are extracted by fitting a curve of impedance measured at each frequency on the equivalent impedance model and extracted parameters are used to estimate SOC. Experiments were conducted on lithium polymer batteries with similar capacities made by different manufacturers to prove the validity of the proposed method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.354-361
• /
• 2005

Physical parameters such as porosity and effective porosity are important physical parameters that determine the transfer and movement of water and solutes in porous media. Various methods of determining these parameters have been developed, with varying degrees of accuracy and applicability. Most of the existing methods produce static results. They do not produce instantaneous and real time of porosity and effective porosity in a porous media. In this study, a new permittivity method called Frequency Domain Reflectometry with Vector analyzer (FDR-V) is proposed to determine the porosity and effective porosity of some sand samples in the laboratory. The advantage of the FDR-V method is that it instantaneously determines the temporal variation of dielectric constants of porous media. Then, the porosity and the effective porosity of porous media are computed using well established empirical equations. Results obtained from the FDR-V method compared favorably with results from other permittivity methods such as gravimetric, injection and replacement tests. The ratio of effective porosity to porosity was $85{\sim}92%$, when FDR-V was used. This value compared favourably with 90%, which has been usually quoted in previous studies. Considering the convenience and its applicability, the measurement system of FDR-V permittivity holds a great potential in porous media and contaminant transport studies.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.2
• /
• pp.63-68
• /
• 2005

Total 12 units of high power klystron-modulator systems as microwave source are under operation for 2.5 GeV electron linear accelerator in Pohang Light Source (PLS) linac. The klystron-modulator system has an important role for the stable operation to improve an availability statistics of overall system performance of klystron-modulator system. RF power and beam power of klystron are precisely measured for the effective control of electron beam. A precise measurement and measurement equipment with good response characteristics are demanded for this. Input power of klystron is calculated from the applied voltage and the current on its cathode. Tiny measurement error severely effects RF output power value of klystron. Therefore, special care is needed to measure precise beam voltage. Capacitive voltage divider (CVD), which divides input voltage as capacitance ratio, is intended for the measurement of a beam voltage of 400 kV generated from the klystron-modulator system. Main parameter to determine standard capacitance in the high arm of CVD is dielectric constant of insulation oil. Therefore CVD should be designed to have a minimum capacitance variation due to voltage, frequency and temperature in the measurement range. This paper will be present and discuss the design concept and analysis of capacitive voltage divider for a pulsed high-voltage measurement, and the empirical relations between capacitance effects and oil temperature variation.

• KSBB Journal
• /
• v.11 no.4
• /
• pp.481-488
• /
• 1996

In spite of diverse applications of chitin derivatives, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. One of methods to reduce such high resistance to chemicals is to make microcrystalline chitin(MCC) by hydrolysis of chitin. Presently, MCC is produced mainly by using high concentration of acid, but this treatment requires an extensive posttreatment to remove or recover acid. An alternative process for MCC production was developed by using dilute hydrochloric acid with ultrasound and hydrogen peroxide. The major parameters for this process were found to be acid concentration, swelling time and temperature, and irradiation time and frequency of ultrasound. The effects of these parameters on MCC molecular weight were investigated. The molecular weight of MCC produced at a typical condition was around 30,000 which was approximately 1/8 of that of chitin and approached to a constant value. This phenomenon was explained by introducing the model of molecular arrangement of cellulose. SEM analysis showed that both chitin and MCC had a fibrous shaped morphology and the fibril size of MCC was much smaller than that of chitin.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.363-366
• /
• 2004

The structural and microwave dielectric properties of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics with sintering temperature were investigated. All the sample of the $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were prepared by conventional mixed oxide method and sintered at $1425^{\circ}C{\sim}1500^{\circ}C$. According to XRD Patterns, hexagonal $Mg_4Ta_2O_9$ phase and cubic $SrTiO_3$ Phase were coexisted. The porosity of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics were reduced with increasing sintering temperature. In the case of $0.7Mg_4Ta_2O_9-0.3SrTiO_3$ ceramics sintered at $1475^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 14.51, 82,596GHz and $-3.14ppm/^{\circ}C$, respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.8 no.1
• /
• pp.5-10
• /
• 2007

Using a reference slurry, ammonium dodecyl sulfate (ADS), an anionic and environmentally friendly surfactant, was investigated as an alternative to BTA for its inhibition and lubrication characteristics. Results demonstrated that the inhibition efficiency of ADS was superior to that of BTA. Coefficient of friction (COF) was the lowest when the slurry contained ADS. This suggested that adsorbed ADS on the surface provided lubricating action thereby reducing the wear between the contacting surfaces. Temperature results were consistent with the COF and removal rate data. ADS showed the lowest temperature rise again confirming the softening effect of the adsorbed surfactant layer and less energy dissipation due to friction. Spectral analysis of shear force showed that increasing the pad-wafer sliding velocity at constant wafer pressure shifted the high frequency spectral peaks to lower frequencies while increasing the variance of the frictional force. Addition of ADS reduced the fluctuating component of the shear force and the extent of the pre-existing stick-slip phenomena caused by the kinematics of the process and collision event between pad asperities with the wafer. By contrast, in the case of BTA, there were no such observed benefits but instead undesirable effects were seen at some polishing conditions. This work underscored the importance of real-time force spectroscopy in elucidating the adsorption, lubrication and inhibition of additives in slurries in CMP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.4
• /
• pp.350-354
• /
• 2009

$Al_{2}O_{3}$ thin films were deposited on GaN(0001) by using a Remote Plasma Atomic Layer Deposition(RPALD) technique with a trimethylaluminum(TMA) precursor and oxygen radicals in the temperature range of $25{\sim}500^{\circ}C$. The growth rate per cycle was varied with the substrate temperature from $1.8{\AA}$/cycle at $25^{\circ}C$ to $0.8{\AA}$/cycle at $500^{\circ}C$. The chemical structure of the $Al_{2}O_{3}$ thin films was studied using X-ray photoelectron spectroscopy(XPS). The electrical properties of $Al_{2}O_{3}$/GaN Metal-Insulator-Semiconductor (MIS) capacitor grown at a $300^{\circ}C$ process temperature were excellent, a low electrical leakage current density(${\sim}10^{-10}A/cm^2$ at 1 MV) at room temperature and a high dielectric constant of about 7.2 with a thinner oxide thickness of 12 nm. The interface trap density($D_{it}$) was estimated using a high-frequency C-V method measured at $300^{\circ}C$. These results show that the RPALD technique is an excellent choice for depositing high-quality $Al_{2}O_{3}$ as a Sate dielectric in GaN-based devices.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.10
• /
• pp.173-179
• /
• 2014

In this paper, a motor parameter identification system has been implemented to improve the performance of the position sensorless stroke controller for linear compressors. In order to control the cooling capability of a refrigerator or an air conditioner in which linear compressors are applied, the piston speed should be controlled. The piston speed control can be obtained by adjusting the frequency or the stroke of linear motors. The dynamic performance of linear compressors depends on how accurately the stroke or the piston amplitude is estimated. The merits and demerits of Constant method and PIM (Parameter Identification Method) concerning the needed memory space and the stroke error are discussed and verified via some experimental studies.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.11 no.2
• /
• pp.159-164
• /
• 2016

A wireless communication system is required to be implemented with the low power circuits because it uses a battery having a limited energy. Therefore, the current mode circuit has been studied because it consumes constant power regardless of the frequency change. However, the clock-feedthrough problem is happened by leak of stored energy in memory operation. In this paper, we suggest the current memory circuit to minimize the clock-feedthrough problem and introduce a technique for ultra low power operation by inducing dynamic voltage scaling. The current memory circuit was designed with BSIM3 model of $0.35{\mu}m$ process and was operated in the near-threshold region. From the simulation result, the clock-feedthrough could be minimized when designing the memory MOS Width of $2{\mu}m$, the switch MOS Width of $0.3{\mu}m$ and dummy MOS Width of $13{\mu}m$ in 1MHz switching operation. The power consumption was calculated with $3.7{\mu}W$ at the supply voltage of 1.2 V, near-threshold voltage.