• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.44-49
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• 2017

A compact planar microstrip-fed ultra-wideband (UWB) antenna with a dual band-notched for UWB application is presented and analyzed. By inserting a U-shaped slot and inverted U-shaped slot into the pot-shaped radiator, two notched bands are achieved. By optimizing the width and length of the U-shaped slots and inverted U-shaped slot, a desired bandwidth of voltage standing wave ratio (VSWR) less than 2.0 can be achieved, ranging from UWB bands with notched dual bands. The proposed antenna is fabricated on an inexpensive FR-4 substrate with overall dimensions of $28.0mm{\times}39.5mm$. The measured results confirm that the proposed antenna covers from 1.775 to over 13.075 GHz with two rejection bands of around 3.325-3.925 GHz and 5.3125-6.025 GHz. In addition, the proposed antenna showed good radiation characteristics and gains in the UWB bands.

• Korean Journal of Radiology
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• v.21 no.4
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• pp.462-470
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• 2020

Objective: To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Materials and Methods: Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. Results: k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Conclusion: Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1002-1004
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• 2003

A ground-based, C-band full polarimetric mobile Scatterometer system has been developed in Malaysia with collaboration between Malaysian Centre for Remote Sensing (MACRES) and Multimedia University (MMU). The main purpose of this system is to measure and monitor backscattering coefficient, ${\sigma }^0$, for earth terrain such as paddy fields, forest and soil surfaces. This paper describes the preliminary results on radar backscatter measurement from paddy field using the mobile C-band Scatterometer system. The measurement campaign was conducted at Sungai Burung area in April 2003. Real time data were collected using four polarization modes (HH, HV, VV and VH), at various incidence angles ranging from 0$^0$ to 60$^0$. The measurement data show consistent results as compared to other reports, which verify the capability of this Scatterometer system as a useful tool for remote sensing.

• Journal of Aquaculture
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• v.20 no.4
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• pp.255-259
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• 2007

Genetic diversity among four populations of Chinese shrimp Fenneropenaeus chinensis from Narodo, Yeonggwang, Taean and Chinese Bohai Bay was assessed by amplified fragment length polymorphism (AFLP) DNA fingerprinting. Total numbers of AFLP bands generated (ranging from 251 to 254) and average percent of polymorphic bands (27.1 to 28.1 %) were similar in the four populations. Heterozygosity and genetic diversity within or among the populations were very low for the populations with average values ranging from 0.1177 to 0.1288 and from 0.1099 to 0.1194, respectively. Analyses of pairwise distance, Fst index and genetic similarity among the populations also revealed the similar results with very low genetic differentiation each other. These results suggest that all the wild populations tested in the present analysis may be belonging to the same genetic origin, and also that they may have a close relationship in genetic structure without any significant differentiation.

• Journal of Sensor Science and Technology
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• v.16 no.6
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• pp.419-427
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• 2007

Single crystal $ZnIn_{2}S_{4}$ layers were grown on a thoroughly etched semi-insulating GaAs(100) substrate at $450^{\circ}C$ with the hot wall epitaxy (HWE) system by evaporating the polycrystal source of $ZnIn_{2}S_{4}$ at $610^{\circ}C$ prepared from horizontal electric furnace. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $ZnIn_{2}S_{4}$ thin films measured with Hall effect by van der Pauw method are $8.51{\times}10^{17}\;electron/cm^{-3}$, $291{\;}cm^{2}/v-s$ at 293 K, respectively. The photocurrent and the absorption spectra of $ZnIn_{2}S_{4}$/SI(Semi-Insulated) GaAs(100) are measured ranging from 293 K to 10 K. The temperature dependence of the energy band gap of the $ZnIn_{2}S_{4}$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)$=2.9514 eV. ($7.24{\times}10^{-4}\;eV/K$)$T^{2}$/(T+489 K). Using the photocurrent spectra and the Hopfield quasicubic model, the crystal field energy(${\Delta}cr$) and the spin-orbit splitting energy(${\Delta}so$) for the valence band of the $ZnIn_{2}S_{4}$ have been estimated to be 167.8 meV and 14.8 meV at 10 K, respectively. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1}$-, $B_{1}$-, and $C_{41}$-exciton peaks.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.41-47
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• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.283-291
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• 2012

In this paper, a compact antenna is designed for the UWB lower half-band WVAN Gbps data-rate transceiver. The proposed antenna broadens the bandwidth less than -10 dB by placing the ring stubs and an open stub on the rectangular monopole above the partial ground and creating multiple resonant current paths. The designed antenna goes through the electromagnetic simulation and is fabricated and the implemented antenna has the characteristics of the return loss lower than -10 dB, the antenna gain greater than 5 dBi, and the efficiency over 80 % in the UWB lower half-band ranging from 3.197 GHz to 4.732 GHz. Therefore, it is thought that the proposed antenna is suitable for the size-reduced and excellently performing wireless communication transceiver.

• Korean Journal of Plant Resources
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• v.19 no.2
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• pp.336-339
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• 2006

This study was conducted to provide the genetic diversity on Safflower collections and to identify the variations which could be utilized in Safflower breeding. The RAPDs analysis was used to clarify the genetic relationships among 32 Safflower collections. Among 37 primers applied in RAPD analysis, 25 primers that generated appropriate PCR products for identification of the genetic characters in safflower collections were used. Amplified PCR showed the highly reproducible bands at $0.1{\sim}4.0kb$. The number of bands amplified in each primer showed the variations ranging from 1 to 9, with the average of 5.6. A total of 25 bands were identified among twenty-five selected primers and 23 bands (19.2%) showed polymorphism. Based on the similarity value of 0.042 in dendrogram derived from the cluster analysis, the 32 Safflower collections were classified into 6 groups. The two main groups, II and III included 12 collections (38%) and 12 collections (38%), respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.327-332
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• 2017

As Internet of Things (IoT) technology advances, there is a growing demand for location-based services (LBSs) to identify users' mobility and identity. The initial LBS system was mainly used to measure position information by measuring the phase of a signal transmitted from a global positioning system (GPS) satellite or by measuring distance to a satellite by tracking the code of a carrier signal. However, the use of GPS satellites is ineffective, because it is difficult to receive satellite signals indoors. Therefore, research on wireless communications systems like ultra-wide band (UWB), radio frequency identification (RFID), and ZigBee are being actively pursued for location recognition technology that can be utilized in an indoor environment. In this paper, we propose an LBS system that includes the 2.45GHz band for chirp spread spectrum (CSS), and the 3.1-10.6GHz band and the 250-750MHz bands for UWB using the IEEE 802.15.4a standard for low power-based location recognition. As a result, we confirmed that the 2.45GHz Industrial, Scientific and Medical (ISM) band RF transceiver and the ranging function can be realized in the hardware and has 0dBm output power.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.102-105
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• 2012

The structural, electrical, and optical properties of layer-by-layer ZnO nanoparticles deposited using sol-gel spin coating technique were studied and now presented. Thicknesses of the thin films were varied by increasing the number of deposited layers. As part of our characterization process, XRD and FE-SEM were used to characterize the structural properties, current-voltage measurements for the electrical properties, and UV-Vis spectra and photoluminescence spectra for the optical properties of the ZnO thin films. ZnO thin films with thicknesses ranging from 14.2 nm to 62.7 nm were used in this work. Film with thickness of 42.7 nm gave the lowest resistivity among all, $1.39{\times}10^{-2}{\Omega}{\cdot}cm$. Photoluminescence spectra showed two peaks which were in the UV emission centered at 380 nm, and visible emission centered at 590 nm. Optical transmittance spectra of the samples indicated that all films were transparent (>88%) in the visible-NIR range. The optical band gap energy was estimated to be 3.21~3.26 eV, with band gap increased with the thin film thickness.