• Journal of electromagnetic engineering and science
• /
• v.1 no.1
• /
• pp.30-36
• /
• 2001

Whereas it is well known that microwave propagation around corners of urban area is estimated well by the uniform geometrical theory of diffraction (UTD), it is not clear how much depolarization occurs at a given receiver position and how much transmission through walls affects to total path loss. This paper presents the results of the ray tracing simulation to answer these questions. Simulations of microwave propagation around corners were performed for various line-of-sight (LOS) and out-of-sight(OOS) positions of a receiver, by summing the electrical fields of reflected, diffracted and transmitted rays coherently. Since height difference between transmitter and receiver, as well as ground plane, causes depolarization, the ray tracing simulation estimates the cross-polarization coupling. It was found that the cross-polarization coupling decreases as receiver moves away from transmitter. Another part of the study focused on the signal transmitted through building walls of the corner. It was found that the transmitted field is dominant at OOS region when the conductivity of the walls is low (for example, lower than 0.0l S/m). The simulation results of the ray tracing technique in this study agreed well with an experimental measurement around corners.

• Transactions on Electrical and Electronic Materials
• /
• v.12 no.6
• /
• pp.241-244
• /
• 2011

An isolator transmits light in the forward direction and blocks light from passing in the reverse direction. It is regarded an essential optical component in medical, industrial, and research lasers for blocking reflection beams that cause optical damage and noise. It is also used as a communicative light intensifier to expand the lifespan of devices and enhance transmission quality. This study analyzed the characteristics of the core components in the construction of a polarization-independent isolator, namely, the walk-off polarizer and the Faraday rotator. Measurement of the extinction ratio of the resultant walk-off polarizer revealed that the ratio between the vertical and horizontal rays was 1,050:1 with a laser output of 0.032 W and 1,010:1 with a laser output of 2.68 W, thus presenting ratios similar to 1,000:1. In addition, the walk-off polarizer and Faraday rotator constructed in this study were used to compare output changes according to changes in power of input light and to check the penetration ratio. Results from the study presented variations in output value according to changes in power of input light. However, the average penetration ratio remained relatively consistent (~81.4%).

• Korean Journal of Remote Sensing
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2010

This paper proposes a new decomposition technique for polarimetric synthetic aperture radar (SAR) images. This new decomposition technique is based on the degree of polarization (DoP) and co-polarized phase-difference (CPD) of the measured polarimetric backscattering coefficients. This decomposition technique is compared with the existing three- and four-component decomposition techniques with the ALOS PALSAR full polarimetric L-band data acquired in 2009. It is shown that the new decomposition technique is better or comparable to the existing techniques for the study areas such as sea, bare soil, forest, and urban area.

• Journal of the Korean Magnetics Society
• /
• v.26 no.6
• /
• pp.179-184
• /
• 2016

For an industrial spin-transfer torque (STT) MRAM, low switching current and high thermal stability are required, simultaneously. For this point of view, it is essential to find magnetic materials which satisfy high spin polarization and strong perpendicular magnetocrystalline anisotropy (MCA). In this paper, we investigate electronic structures and MCA energies of perovskite $CoFeX_3$ (X = O, F, S, Cl). For X = F and Cl, spin polarization at the Fermi level are 97 % and 96 %, respectively, which are close to a half metal. Furthermore, Co-terminated 5-monolayer (ML) $CoFeX_3$ (X = O, F, S, Cl) films show perpendicular MCA. In particular, the MCA energy of the Co-terminated $CoFeCl_3$ is about 1.0 meV/cell which is three times larger than that of a 5-ML CoFe film. Therefore, we expect to realize a magnetic material with high spin polarization and strong perpendicular MCA energy by utilizing group 6 and 7 elements in the periodic table, and to contribute to commercializing of the STT-MRAM.

• Journal of the Korean Magnetics Society
• /
• v.17 no.5
• /
• pp.194-197
• /
• 2007

Understanding the spin polarization (P) has been an ongoing research challenge. The $Co_{1-x}Mn_x$ (x=0.27, 1) and $Co_{1-x}Fe_x$ (x=0, 0.5, 1) films were prepared using UHV-MBE system. For these films, the magnetic properties and spin polarization were investigated using SQUID and Meservey-Tedrow technique, respectively. Although measured P is uncorrelated to the bulk magnetic moment (M) in Co-Fe and Ni-Fe alloy films, it correlates with M in some alloys such as Co-Mn and Ni-Cu. The results can be understood by the tunneling currents made up of the hybridized sp-d electrons near the Fermi-energy level. Our work shows the feasibility to tailor new materials with large P values.

• Journal of the Korean Ceramic Society
• /
• v.52 no.5
• /
• pp.308-314
• /
• 2015

The electrochemical performance and Cr poisoning behavior of $La_{1-x}Ba_xCo_{0.9}Fe_{0.1}O_{3-{\delta}}$ (LBCF, x = 0.3, 0.4, 0.5) and $La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LSCF) cathodes were investigated for solid oxide fuel cells (SOFCs). The polarization resistance of the LBCF/GDC/LBCF symmetrical cell was found to decrease with increasing Ba content (x value). This phenomenon might be associated with the high oxygen vacancy concentration in the LBCF sample, with x = 0.5. In addition, there was no chromium poisoning in the LBCF cathode. On the other hand, the polarization resistance of the LSCF cathode was found to significantly increase after exposure to gaseous chromium species; it appears that this result stemmed from the formation of $SrCrO_4$ phase. Therefore, it can be expected that LBCF can be a durable potential cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFC).

• Journal of Pharmacopuncture
• /
• v.22 no.4
• /
• pp.253-259
• /
• 2019

Objectives: It is reported that tumor-associated macrophages (TAMs) contribute to cancer progression by promoting tumor growth and metastasis. The purpose of this study is to investigate the effect of different fractions of Adenophora triphylla var. japonica (AT) on the polarization of macrophages into the M2 phenotype, a major phenotype of TAMs. Methods: We isolated hexane, ethyl acetate, and butanol fractions from crude ethanol extract of AT. The cytotoxicity of AT in RAW264.7 cells was examined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RAW264.7 cells were polarized into the M2 phenotype by treatment with interleukin (IL)-4 and IL-13. The expression of M2 macrophage marker genes was detected by reverse transcription polymerase chain reaction (RT-PCR). The phosphorylation level of signal transducer and activator of transcription 6 (STAT6) was investigated by western blot analysis. The migration of Lewis lung carcinoma (LLC) cells was examined by transwell migration assay using conditioned media (CM) collected from RAW264.7 cells as a chemoattractant. Results: Among various fractions of AT, the ethyl acetate fraction of AT (EAT) showed the most significant suppressive effect on the mRNA expression of M2 macrophage markers, including arginase-1, interleukin (IL)-10 and mannose receptor C type 1 (MRC-1), up-regulated by treatment of IL-4 and IL-13. In addition, EAT suppressed the phosphorylation of STAT6, a critical regulator of IL-4 and IL-13-induced M2 macrophage polarization. Finally, the increased migration of Lewis lung carcinoma (LLC) cells by CM from M2-polarized RAW264.7 cells was reduced by CM from RAW264.7 cells co-treated with EAT and M2 polarization inducers. Conclusion: We demonstrated that EAT attenuated cancer cell migration through suppression of macrophage polarization toward the M2 phenotype. Additional preclinical or clinical researches are needed to evaluate its regulatory effects on macrophage polarization and anti-cancer activities.

• Aerospace Engineering and Technology
• /
• v.6 no.2
• /
• pp.211-218
• /
• 2007

Dual-polarization means to use two orthogonal polarizations, namely two independent channels in communication. This can be used to deal with high datarate caused by large amount of observed data in future LEO satellite. However, when two orthogonal polarizations are not perfectly independent to each other in practical, interference is probably raised in each channel, meaning that noise level in passband increases. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonal polarized to the transmitting antenna. In this paper, the influence of XPD on the communication between satellite and ground station was analyzed under the assumption that X-Band dual-polarization was applied to KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). Through analysis, it was shown that more than 3dB of link margin was still achievable despite of worst axial ratio, 2.5dB, at ground station antenna when axial ratio of satellite antenna was about 0.5dB under 99% of environmental availability.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.38 no.1
• /
• pp.32-37
• /
• 2024

The aim of this study was to investigate the role of Daesiho-tang (Da Chai Hu-Tang) water extract (DSTE) in regulating chronic stress-induced cancer progression, focusing on its activity in modulating tumor-associated macrophages (TAMs). Different stimuli can polarize TAMs into immune-stimulating M1 macrophages or immunosuppressive M2 macrophages. During cancer progression, M2 phenotype increases and supports tumor growth, angiogenesis and metastasis. Notably, chronic stress-induced catecholamines promote M2 macrophage polarization. In this study, we investigated whether DSTE regulates norepinephrine (NE)-induced M2 macrophage polarization in RAW 264.7 mouse macrophage cells. Even though NE itself did not increase the expression of M2 markers, the conditioned media of NE-treated 4T1 mouse breast cancer cells (NE CM) significantly up-regulated M2 markers in RAW 264.7 cells, suggesting that NE-regulated cancer cell secretome stimulated M2 polarization. However, such increase was abrogated by DSTE. NE CM also induced phosphorylation of signal transducer and activator of transcription 6 (STAT6) in RAW 264.7 cells, which was clearly reversed by pretreatment with DSTE, demonstrating that DSTE inhibited M2 polarization by inactivating STAT6. Finally, M2-polarized RAW264.7 cells by NE CM markedly increased the migration of 4T1 cells. However, such increase was completely reversed by co-treating RAW264.7 cells with NE CM and DSTE, indicating that DSTE attenuated cancer cell migration by blocking M2 polarization. Taken together, our results suggest a probable use of DSTE for cancer patients under chronic stress by regulating M2 macrophage polarization.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.868-871
• /
• 2006

In-plane switching characteristics of PI rubbed ITO sandwich cell with low molecule FLC (ferroelectric liquid crystal) surface was investigated. FLC on the surface is governed by the applying frequency and surface condition. By controlling the Ps (spontaneous polarization) direction of dual FLC surfaces, switching characteristics are improved without change of cell structure.