• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1335-1342
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• 2010

This paper presents design and measurement result of S-band, $\bigcirc$ kW solid-state transmitter and receiver for active array radar system. Transmitter characteristics show 63 dB gain, 200 usec pulse width(max.), 10 % duty(max.) and 63 dB pulse to pulse stability. Receiver characteristics show 23 dB gain and 3.2 dB noise figure. Receiving mode for pulse network analyzer is used for pulse to pulse stability measurement. Measurement results satisfies all specification.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.163-167
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• 2010

Bacillus subtilis 168 secreted antimicrobial substance(s) into culture medium and culture supernatant inhibited growth of some Gram positive bacteria. B. cereus and Listeria monocytogenes were the most sensitive organisms. The antimicrobial activity was destroyed when culture supernatant was treated by protease and proteinase K, indicating the proteinous nature of the substance (bacteriocin). The molecular weight of the bacteriocin was estimated to be 5 kDa by Tricine SDS-PAGE. B. cereus ATCC 14579 cells were killed when exposed to the bacteriocin, indicating that the mode of inhibition was bacteriocidal. These results show that B. subtilis 168 could be useful as a starter for fermented foods such as cheonggukjang where B. cereus contamination is a major concern.

• Journal of the Korean Chemical Society
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• v.60 no.6
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• pp.410-414
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• 2016

The anharmonic frequency of a local OH stretching mode of a water monomer and dimer was calculated using various levels of density functional theory. The quantum chemical potential energy curves as a function of the OH bond distance were calculated, and they were fitted with the Morse potential function to analytically obtain the fundamental transition frequency. By comparing those values with the frequencies similarly calculated using an ab initio quantum chemical method, the coupled cluster theory including both single and double excitations with the perturbative inclusion of triple excitation in the complete basis limit, the accuracy of various density functional methods in the calculation of anharmonic vibration frequency of water molecules was assessed. For a water monomer, X3LYP and B3LYP methods give the best accuracy, whereas for a water dimer, B972, LCBLYP, ${\omega}B97X$, ${\omega}B97$ methods show the best performance.

• 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.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.188-192
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• 2003

A multilayer two-stage LC bandpass filter using low-temperature cofired-ceramic (LTCC) is proposed in this paper. The proposed bandpass filter is composed of two ceramic substrates with different dielectric constant instead of single ceramic material from top to bottom layer. The bandpass filter size is $2.0 mm{\times}1.2 mm{\times}0.8 mm$. Positioning of attenuation polefrequency, importance parameter for a performance of filter, is discussed using even-odd mode analysis by tuned capacitance of coupling capacitor and those results is implemented to LTCC filter circuit. Measured filter performances show that the insertion losses are -4.5dB, -4.1dB at 2.45GHz, 2.75GHz and the return losses are -8.5dB, 8.7dB.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.6
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• pp.272-275
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• 2004

A balanced single side-band (SSB) mixer employing a sub-harmonic configuration is designed for up and down conversions in K-band. The designed mixer uses anti-parallel diode (APD) pairs to effectively eliminate even harmonics of the local oscillator (LO) spurious signal. To reduce the odd harmonics of LO at the RF port, we employ a balanced configuration for LO. The fabricated chip shows 12$\pm$2dB of conversion loss and image-rejection ratio of about 20dB for down conversion at RF frequencies of 24-27.5GHz. As an up-conversion mode, the designed chip shows 12dB of conversion loss and image-rejection ratio of 20 ～ 25 dB at RF frequencies of 25 to 27GHz. The odd harmonics of the LO are measured below -37dBc.

• Korean Journal of Pharmacognosy
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• v.10 no.2
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• pp.73-77
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• 1979

Antiinflammatory action of phytolaccosides B and E isolated from the roots of Phytolacca americana was investigated and compared with that of aescin. Phytolaccoside B, when it was administered intravenously, exerted a potent inhibitory effect on the transudation caused by absorptive sponge pellet implanted s.c. in rats and on carrageenin induced edema in rats. Phytolaccoside E showed a weaker action than Phytolaccoside B did. Hemolytic potency of the saponins was decreased in the order of aescin, phytolaccosides B and E showing a same tendency as in antiinflammatory action. The experimental result suggests that the mode of action of phytolaccosides is the same as that of aescin.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.11
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• pp.577-582
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• 2004

In this paper, lumped equivalent circuits for a conventional parallel directional coupler are proposed. This equivalent circuits only have self inductance and self capacitance, so we can design exact lumped equivalent circuit. The equivalent circuit and design formula for the presented lumped element coupler is derived based on the even- and odd-mode properties of parallel-coupled line. By using the derived design formula, we have designed the 3dB and 4.7dB MMIC couplers at the center frequency of 3.4GHz and 5.6GHz respectively. Measurements for the designed MMIC directional couplers show at 4dB and 5.2dB-coupling value at the center frequency of 3.4GHz and 5.6GHz. Excellent agreements between simulation results and measurement results on the designed directional couplers show the validity of this paper

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.665-674
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• 2000

This paper deals the HVDC system stability according to controller types. In this paper, in order to evaluate the stability, some important properties of the HVDC. such as $d{\tau}/d{\alpha}\;,\;dV/d{\alpha}$ and dP/dI stability in different control modes, are analysed. Furthermore, Maximum available power according to controller types are calculated. This paper shows a generated formulation of control sensitivity for control modes, aids in the design of the controller and the operating mode determination. Finally, a simulation is performed by Math/CAD, and a simulation results are verified.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.259-261
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• 1999

In this paper, we investigated the frequency dependences of AC loss and the magnetic properties of a superconductor using magnetization method. We used the YBCO bulk superconductor sample which has a square-shaped cross sectional area of $6mm{\times}6mm$. and 43mm-long in axial direction. The applied AC magnetic field was parallel to the direction of sample axis. It is observed that YBCO bulk has the diamagnetic properties. AC loss calculation of YBCO bulk superconductor was performed by evaluating the total area of magnetization traces. We performed two cases of experiments, one for $B_m<B_p$ and the other for $B_m<B_p$. The experiments showed that the AC loss dependences on frequency were different in each mode, as was indicated in other publications.