• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1529-1536
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• 2010

In this paper, we propose a Axially displaced ellipse gregorian antenna with conical feed horn operating in Ku-band. For fast searching satellite position, it is designed the sub-reflector rotates about $1.5^{\circ}$ tilted by the central axis. the curvature and feed center of the main-reflector and sub-reflector are optimized to achieve maximum antenna efficiency. The designed reflector antenna shows the gain of 33dB and the cross polarization level of less than -21dB and the side-lobe level of less than －14 dB at 12.2 GHz. and C/N ratio of 19dB is proved by reception experiment of Koreasat with fabricated antenna.

• Korean Journal of Clinical Pharmacy
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• v.7 no.2
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• pp.51-63
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• 1997

The effect of cimetidine administration on the pharmacokinetic parameters of cyclosporine were determined in healthy voluteers. This study was performed in 10 volunteers of age ranged 22-48 years and body weight 48-62 kg. This study was performed with cross-over design. Mono cyclosporine and cyclosporine metabolites was extracted from whole blood analysed by fluororescence polarization immune assay (TDX-FLX, Abbott). After coadministration of cimetidine (300 mg) with cyclosporine (300 mg) orally, maximum concentration of mono cyclosporine was significantly increased $1221{\pm}143\;ng/ml\;to\;1562{\pm}184\;ng/ml$ (P<0.05), area under the time curve of cyclosporine (12 hr) also was significantly increased $7478{\pm}829\;ng/ml{\cdot}hr\;to\;9721{\pm}879\;ng/ml{\cdot}hr$ (P<0.05) and absolute baioavailability of cyclosporine was increased $50\pm5.6\%\;to\;57.6\pm6.1\%\;(P<0.05)$ compared to control group. The blood concentrations of cyclopsorine metabolites were significantly decrased (P<0.05) after coadministration of cimetidine. In cimetidine pretreated group, blood mono cyclosporine concentrations were increased significan시y $1220.0\pm203.00\;ng/ml\;to\;1510.0\pm204.00\;ng/ml$ compared with control group (P<0.05). In the mono cyclosporine pharmacokinetic parameter after oral administration absorption rate and maximum concentration were significantly higher in cimetidine coadministered and pretreated group than control group (P<0.05). The ratio of metabolites and mono cyclosporine concentrations was decreased significantly from $70.8\%\;in\;control\;to\;34.8\%$ in coadministration of cimetidine orally. As matter of facts these reults are considered to inhibition of cyclosporine hepatic metabolism and increasing of cyclosporine absorption rate in gastrointestinal tract because of maintaining cyclosporine stability in elevated gastric pH by cimetidine. We considered, it appeares that cimetidine increase bioavailability of cyclosporine by increasing oral absorption and by decreasing hepatic clearance. But the absorption and clearance of cyclosporine was highly variable individually, and therefore we consider that cyclosporine blood level monitoring would be essential in patients with cimetidine co-administration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.800-807
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• 2016

In this paper, we study the characteristics of dual band microstip antenna with modified inset feeder and a single slot. The modified inset feeder consists of the vertical inset feeder placed in x direction and the horizontal one in y direction for shortening the total length of inset feeder. The optimun feeding position for good impedance matching at two resonant frequencies can be easily found by adjusting the horizontal inset distance. And Various frequency ratios can be simply obtained by the parameters of slot. The measurements for fabricated antenna prototypes are carried out for validation. The measured results show a tunable frequency ratio from 1.25 to 1.88 with the variation of slot parameters. It is worthwhile to point out that the radiation patterns are similar at both bands. and below -20.0 dB of cross polarization level at the E plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1070-1076
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• 2007

In this paper, we study the characteristics of dual band microstrip antenna with the wedge-shaped radiation patch added the slot using air substrate. Wedge-shaped patch antenna with air substrate is avoided the large probe reactance associated with a thick substrate owing to the use of short probe and good impedance matching over a wide frequency range can be obtained. Slot on the antenna radiator varies the reactance component according to the employed frequency and affect the resonance freaqency of the antenna, therefore the antenna can resonate at the dual band(cellular and PCS band). The slot length and position have an effect on the bandwidth and input impedance of the antenna are optimized by simulation. From the experiment results for the fabricated antenna, -10 dB of $S_{11}$ is content with the allocated bandwidth of Cellular and PCS system and - 15 dB of cross polarization level. From the results of this paper, it has been confirmed that the proposed antenna can be used as the base station antenna fur Cellular and PCS band.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.71-72
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• 2013

In this paper, a design method for a compact slot antenna for 5.8 GHz RFID band (5.725-5.875 GHz) is studied. The proposed slot antenna is size-reduced by bending both ends of the straight slot in "${\Gamma}$"-shape, and a rectangular feed patch is located inside the slot. The effects of slot length, location of feed patch, and width and length of feed patch on the antenna performance are examined. A prototype antenna with optimized parameters for 5.8 GHz band is fabricated on an FR4 substrate and tested experimentally. The experimental results show that the frequency band for a VSWR < 3 ranges 5.72-6.13 GHz (bandwidth 410 MHz), and it corresponds fairly well with the simulated band 5.64-5.97 GHz (bandwidth 330 MHz). The fabricated antenna shows good radiation performance such as maximum power density in both directions normal to the slot plane, and low cross-polarization level of < -20 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1131-1137
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• 1999

In this paper, a novel design method of an apertured coupled microstrip patch antenna with the single feeding structure is proposed for dual resonance frequencies with mutually perpendicular polarizations. The characteristics of this antenna are experimentally investigated. In order to achieve this goal, a new type of square patch with double notches is used as a radiator and the crossed slot and the bended mictrostrip feeder are adopted for the dual polarizations in the aperture-coupled structure. For the application of the proposed antenna, a Ku-band Tx/Rx $2\times$ subarray antenna is designed and manufactured. Also, the applicability of the antenna as a ground terminal is examined through performance analysis. According to the measurement, the gain of the antenna is 10dBi at the center frequencies of Tx and Rx, the side lobe level is lower than -13dB, and the cross polarization lebel is below 17 dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2763-2768
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• 2013

In this paper, a design method for a compact slot antenna for 5.8 GHz RFID band (5.725-5.875 GHz) is studied. The proposed slot antenna is size-reduced by bending both ends of the straight slot in "I"-shape, and a rectangular feed patch is located inside the slot. The effects of slot length, location of feed patch, and width and length of feed patch on the antenna performance are examined. A prototype antenna with optimized parameters for 5.8 GHz band is fabricated on an FR4 substrate and tested experimentally to verify the results of this study. The experimental results show that the frequency band for a VSWR < 3 ranges 5.72-6.13 GHz (bandwidth 410 MHz), and it corresponds fairly well with the simulated band 5.64-5.97 GHz (bandwidth 330 MHz). The fabricated antenna shows good radiation performance such as maximum power density in both directions normal to the slot plane, low cross-polarization level of < -20 dB, and realized gain > 0 dBi within the frequency band.

• Korean Journal of Remote Sensing
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• v.25 no.4
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• pp.383-389
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• 2009

The main objective of the research is a feasibility study on the intertidal zone using a X-band radar satellite, TerraSAR-X. The TerraSAR-X data have been acquired in the west coast of Korea where large tidal flats, Ganghwa and Yeongjong tidal flats, are developed. Investigations include: 1) waterline and backscattering characteristics of the high resolution X-band images in tidal flats; 2) polarimetric signature of halophytes (or salt marsh plants), specifically Suaeda japonica; and 3) phase and coherence of interferometric pairs. Waterlines from TerraSAR-X data satisfy the requirement of horizontal accuracy of 60 m that corresponds to 20 cm in average height difference while current other spaceborne SAR systems could not meet the requirement. HH-polarization was the best for extraction of waterline, and its geometric position is reliable due to the short wavelength and accurate orbit control of the TerraSAR-X. A halophyte or salt marsh plant, Suaeda japonica, is an indicator of local sea level change. From X-band ground radar measurements, a dual polarization of VV/VH-pol. is anticipated to be the best for detection of the plant with about 9 dB difference at 35 degree incidence angle. However, TerraSAR-X HH/TV dual polarization was turned to be more effective for salt marsh monitoring. The HH-HV value was the maximum of about 7.9 dB at 31.6 degree incidence angle, which is fairly consistent with the results of X-band ground radar measurement. The boundary of salt marsh is effectively traceable specifically by TerraSAR-X cross-polarization data. While interferometric phase is not coherent within normal tidal flat, areas of salt marsh where the landization is preceded show coherent interferometric phases regardless of seasons or tide conditions. Although TerraSAR-X interferometry may not be effective to directly measure height or changes in tidal flat surface, TanDEM-X or other future X-band SAR tandem missions within one-day interval would be useful for mapping tidal flat topography.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.694-705
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• 2006

In this paper, the linear active phased array antenna system operated in Ku DBS band was designed and experimented. The antenna system was composed of sixteen radiating active channels and Wilkinson power combiners with 16-channel inputs, a stabilizing DC bias and phase control board. Electrical beams of the antenna system can be formed by controling the phase-states of 3-bit digital phase shifter inside each active channel by virtue of the phase control board. The amplitude and phase deviations measured between active channels were less than ${\pm}0.8dB$ and ${\pm}15^{\circ}$, respectively, and the noise figure of each active channel was measured less than 1.2 dB in the operating band. The measured performances of the overall antenna system showed the antenna gain of more than 23.07 dBi and the sidelobe level of less than -11.17 dBc, and the bore-sight cross-polarization level of less than -12.75 dBc in the operating band. Also, by phase-controlling active channels, the beam scan patterns at $10^{\circ},\;20^{\circ},\;30^{\circ}$ were measured, and the losses caused by the corresponding beam scanning were 1.1 dB, 2.5 dB and 3.6 dB from the measurements, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.711-719
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• 2011

A study of miniaturization of an L-band orthomode transducer(OMT) for field experiments of radar backscatter is presented in this paper. The proposed OMT is not required the additional waveguide taper structures to connect with a standard adaptor by the newly designed junction structure which bases on a waveguide taper. Total length of the OMT for L-band is about 1.2 ${\lambda}_o$(310 mm) and it's a size of 60 % of the existing OMTs. And, to increase the matching and isolation performances of each polarization, two conducting posts are inserted. The bandwidth of 420 MHz and the isolation level of about 40 dB are measured in the operating frequency. The L-band scatterometer consisting of the manufactured OMT, a horn-antenna and network analyzer(Agilent 8753E) was used STCT and 2DTST to analysis the measurement accuracy of radar backscatter. The full-polarimetric RCSs of test-target, 55 cm trihedral corner reflector, measured by the calibrated scatterometer have errors of -0.2 dB and 0.25 dB for vv-/hh-polarization, respectively. The effective isolation level is about 35.8 dB in the operating frequency. Then, the horn-antenna used to measure has the length of 300 mm, the aperture size of $450{\times}450\;mm^2$, and HPBWs of $29.5^{\circ}$ and $36.5^{\circ}$ on the principle E-/H-planes.