• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.907-915
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• 2009

Spectrum sharing between wireless systems becomes a critical issue due to emerging new technologies and spectrum shortage. Recently, IMT system has been allocated in the same frequency C band (3400-4200MHz) along with FSS services on co-primary basis, which means that harmful interference probability may be inspired. In this paper, to estimate the spectrum sharing between IMT and FSS systems, the minimum separation distances have been evaluated considering major factors such as the clutter loss in some areas and the elevation angle of FSS earth station, and using I/N=-10dB which is fundamental criterion for coexistence.

• 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.648-658
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• 2006

We propose a thin frequency selective surface(FSS) superstrate etched on a substrate for dual-band directivity enhancement, and present a design method of the superstrate. In the proposed new design, two FSS arrays with the same periodicity, but with different alignments are placed above and below a thin dielectric layer to overcome the problem of conventional superstrates for dual band directivity enhancements. Based on the unit-cell simulation, several important parameters that characterize the thin FSS superstrate are investigated, and the procedure for designing such a superstrate is described. We compare the resonant frequencies and the qualify factors of the unit cell with those of three FSS antenna composites with different quality factors, and identify the quality factors which support similar directivity enhancement at the dual-band directivity enhancement. It was found that there is an optimum FSS array size of a superstrate to enhance the directivity most efficiently. Measured results for a fabricated superstrate show a good agreement with the simulated ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1242-1246
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• 2007

In this study, FSS(Frequency Selective Surface) with Koch Fractal Curve slot is positioned on the conventional single layer microstrip patch antenna. Numerical results of the proposed antenna bandwidth and the antenna gain are increased compared with those of the conventional single layer microstrip patch antenna. In the future, the fractal geometry of the slot in FSS(Frequency Selective Surface) as a supplementary microstrip patch is researched for the enhancement of the microstrip patch antenna characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.123-130
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• 2013

In this paper, the delamination and failures in frequency selected surface(FSS) caused by residual stresses in the FSS embedded hybrid composites due to the difference between the coefficients of thermal expansion of components and the transmission characteristic changes due to deformation of FSS patterns by residual stresses were studied. FSS may have different electromagnetic characteristics depending on the type of element, design variables, and arrangement. Design variables of dipole FSS were determined using PSO(Particle Swarm Optimization) to obtain the transmission characteristic for the target resonant frequency. Subsequently, the design variables of other types of N-pole(tripole, cross dipole, and Jerusalem cross) were determined based on the dimensions of the dipole for the comparisons of residual stresses of FSS embedded composite structures and transmission characteristics. In addition, effects of FSS pattern, and stacking sequence of composite laminates were considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3431-3436
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• 2013

Band-notched ultra-wideband (UWB) antennas using frequency selective surfaces (FSSs) are presented. The proposed antennas utilized the band rejection characteristic of typical FSS unit cells. We loaded the FSS unit cells on the same plane of planar UWB antenna. These antennas are designed to reject the interference from the wireless local area network band, 5.15-5.825 GHz in the UWB band, 3.1-10.6 GHz. The measured peak gains of the proposed antennas are more than 2 dBi at both operation edge and center frequencies, and sufficient to apply for commercial purpose. The antennas are small size and planar shape for the purpose of the small mobile application, and enhanced design freedom by using various existing FSS unit cells.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.512-520
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• 2016

In this paper, a miniaturized frequency selective surface(FSS) for bandstop operation that provides stability for an angle of incidence and polarization is presented. The proposed miniaturized FSS has the unit cell of hexagonal structure with triangular loops and size of the unit cell is $0.081{\lambda}{\times}0.081{\lambda}$ at 2.5 GHz operating frequency, which is very small compared to operating wavelength. In addition, unlike the conventional design, which requires complicated design parameters, the proposed FSS is easily expanded to the desired operating frequency for 2~8 GHz, by controlling the specific design parameters. To validate the simulation results, the FSS structures having different operating frequencies, 2.5 GHz, 5 GHz and 8.2 GHz were designed, fabricated and measured. The comparisons between the simulation and the measured results show good agreement. The proposed miniaturized FSS can provide better frequency stability for different incidence angles and polarizations.

• Natural Product Sciences
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• v.23 no.1
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• pp.61-68
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• 2017

This study was performed to investigate the ameliorating effects of steamed soybeans (SS) and fermented SS (FSS) on lipid metabolism in high-fat diet-induced obese mice. ICR mice were divided into four groups and given the following different diets: normal diet (ND), high-fat diet (HFD), HFD with 1% SS (HFD + SS), and HFD with 1% FSS (HFD + FSS). After 14 weeks, the body weight gain was higher in the HFD group compared with the ND group but lower in the HFD + FSS group compared with the HFD group. Plasma levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein-cholesterol, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly higher in the HFD group compared to the ND group, but lower in the HFD + SS and HFD + FSS groups compared with the HFD group. In addition, leptin concentration in plasma was lower in the groups fed HFD + SS and HFD + FSS compared with the HFD group. The accumulation of hepatic TG and TC was significantly inhibited in the HFD + SS and HFD + FSS groups. Furthermore, SS and FSS attenuated lipid peroxidation and nitric oxide formation in the liver induced by the high-fat diet. These results suggest that soybeans, especially FSS, may be useful in preventing obesity-induced abnormalities in lipid metabolism.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.607-615
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• 2019

In this paper, the electromagnetic effects on the discontinuity structures of the frequency selective radome in manufacturing process based on the X-band were analyzed. In order to fabricate a curved radome using a planar frequency selective surface structure, it is assumed that gaps, slanted gaps, pattern damage, and pattern misalignment between FSS patterns, which are discontinuous elements that can occur at the joint surface of the FSS panel. FSS specimens including continuous elements were fabricated and the frequency transmission characteristics were measured in a free space measurement environment. From the measurement results, resonance frequency shift, transmission performance degradation, and bandwidth variations were found to be the largest when the damaged pattern was bonded to the junction of FSS panels.

• Korean Journal of Psychosomatic Medicine
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• v.9 no.2
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• pp.164-173
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• 2001

Objectives : Fatigue is a common symptom in primary medical care and has nonspecific and highly subjective features. So it has been difficult to define and measure fatigue, especially those present without any organic diseases. This study was conducted to evaluate the validity of the Fatigue severity scale(FSS) in patients with persistent fatigue who were free of any organic diseases or psychiatric disorders of depression or anxiety. Methods : Subjects consisted of 45 controls, 44 fatigued patients and 43 psychiatric patients with depression or anxiety. They all completed the fatigue severity, modified Bepsi stress, and Hospital anxiety and depression scales. Chalder fatigue scale was administrated randomly in 30 of them. Data were analyzed for reliability and validity of the FSS. Results: Cronbach's a coeffient of FSS was 0.929, and the Pearson correlation coefficient for test-retest was 0.916(p<0.01). ANCOVA for discriminant validity revealed that there were significant differences in mean FSS values among the three groups. The fatigue group had significantly higher FSS value than the other two groups. The psychiatric group also had significantly higher FSS value than the control group. The Pearson correlation coefficient for convergent validity by comparing FSS with Chalder fatigue scale was 0.782(p<0.01). Using FSS index 3.22 as the cut-off point, sensitivity was 84.1% and specificity was 85.7% for the fatigue and control groups, respectively. Conclusion : Results suggested the clinical application of the FSS to be a useful measurement for distinguishing fatigue between patients with physiologic fatigue and psychiatric patients with depression or anxiety.

• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.109-115
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• 2018

Obesity is a worldwide disease caused by the excessive proliferation of adipocytes. Multiple factors, including melatonin and physical loading, are involved in the control of obesity. Melatonin has been shown to induce apoptosis on preadipocytes while physical loading such as fluid shear stress (FSS) affects the proliferation and differentiation of adipocytes. Here, we studied the combined effects of melatonin and FSS on 3T3-L1 preadipocytes. For physical loading, preadipocytes were stimulated with a maximum dynamic fluid shear stress of 1 Pa at 1 Hz for 2 hours with/without melatonin. The experiment conditions were divided into four groups: (1) control, (2) 1 mM melatonin treatment, (3) FSS, and (4) combined 1 mM melatonin and FSS. All groups had a fixed duration time of 2 hours. ERK, p-ERK, COX-2, $C/EBP{\beta}$, $PPAR{\gamma}$, osteopontin, Bax, caspase-3 and caspase-8 proteins were assessed by Western blot analysis. GAPDH was used as a control. Results showed that combined melatonin and FSS treatment activated the ERK/MAPK pathway but not COX-2. Furthermore, combined melatonin and FSS treatment significantly decreased $C/EBP{\beta}$ and $PPAR{\gamma}$ compared to other groups. However, caspase-3 and caspase-8 did not result in significant changes. In summary, combined melatonin and FSS appears to have the potential to inhibit adipogenesis and treat obesity.