• Journal of the Korean Magnetics Society
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• v.21 no.4
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• pp.127-131
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• 2011

In this paper, we study the electronic and magnetic properties of Cr substituted SiTe in the rock-salt structure compound using the full potential linearized augmented plane wave method within the generalized gradient approximation to the exchange correlation potential. Two stoichiometries are studied: $CrSi_3Te_4$ with 25 %, and $CrSiTe_2$ with 50 % Cr substitution. We found, from the total energy calculations, that the equilibrium lattice constant for cubic $CrSi_3Te_4$ is 11.64 a.u. and a = 7.89 a.u. and c = 11.13 a.u. for tetragonal $CrSiTe_2$. The integer value of the calculated magnetic moment per unit cell, $4{\mu}_B$ for $CrSiTe_2$ suggests that this compound is halfmetallic. The magnetic moment per unit cell for $CrSi_3Te_4$ is slightly larger than $4{\mu}_B$. The magnetic moment on Cr atoms are 3.61 and $3.62{\mu}_B$ in the $CrSi_3Te_4$ and $CrSiTe_2$, respectively. The presence of Cr atoms causes that the other atoms become slightly magnetized in both compounds. The electronic properties and the magnetism are discussed with the calculated spin-polarized density of states.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.2
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• pp.121-127
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• 2011

Skin darkness is the source of trouble to many women. Skin darkness is the state that while skin redness and brightness are reduced, skin yellowness is increased. Skin translucency which is measured by skin color, especially brightness is an another expression of skin darkness. Skin brightness is usually expressed by L value of $L^{*} \;a^{*}\; b^{*}$ (CIELAB color space system). However, it is hard to find the relationship between L value and perceptive efficacy such as translucency because the L value is just a factor of evaluation of skin darkness. The skin with high translucency has high scattering reflective light value than low value. In this study, we measured the skin translucency of 20 ~ 30 ages men and women face by both our designed previous device which use polarized light to detect surface and scatter reflective light independently and $Lumiscan^{TM}$ which is improved designed to confirm our new device working ability by calculation of relationship between trnaslucency and scattering reflective light value. The result of this study indicate that there is a high correlation (R = 0.732, p < 0.01) between translucency and scattering reflective light value, and suggest that $Lumiscan^{TM}$ is portable and easy measuring device more that previous device.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.884-889
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• 1998

Amorphous silicon films of large area have been crystallized by a line shape excimer laser beam of one dimensional scanning with a gaussian profile in the scanning direction. In order to characterize the crystalline phase transition of thickness variables in excimer laser annealing(ELA), angle wrapping method was used. And also to characterize the residual stresses of crystalline phase transition in the case of angle wrapped-crystalline silicon on corning 7059 glass, polarized raman spectroscopies were measured at various laser energy density and substrate temperature. The residual stress varies from $9.0{\times}10^9$ to $9.9{\times}10^9$, and from $9.9{\times}10^9$ to $1.2{\times}10^10$dyne/${cm}^2$ of the substrate temperature at room temperature and varies from $8.1{\times}10^9$ to $9.0{\times}10^9$, and from $9.0{\times}10^9$ to $9.9{\times}10^9$dyne/${cm}^2$ of the substrate temperature at $400^{\circ}C$ as a function of direction from surface to substrate. According to the direction from the surface in liquid phase to the interface and from the interface to near the substrate in solid phase of recrystallized Si thin film, respectively. Thus, the stress is increased from(Liquid phase to solid phase) with phase transition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.769-777
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• 2010

In this paper, a switchable circularly polarized microstrip patch antenna using PIN diodes and corner slots on ground plane is proposed at 2.4 GHz. The proposed antenna has a square microstrip patch and ground plane that consists of two pair of slots and PIN diodes. The electrical lengths of the slots are adjusted by using the switching characteristic of the PIN diode, so the polarization of the proposed antenna can be switchable between linear, left-handed(LH) and right-handed(RH). By separating the ground plane for the DC bias, the size reduction effect is also obtained. When the proposed antenna is operated as linear polarization, the return loss and impedance bandwidth are 15 dB, 59 MHz, and when operated as LH and RH polarization, the minimum axial ratio and 3-dB axial ratio bandwidth are 1.17 dB, 1.67 dB, 28 MHz, and 32 MHz, respectively.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.212-218
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• 2020

When Radiofrequency energy is applied to the human body, the vibration width is very short. Therefore, the electrolyte burn generated when using the direct current does not occur. Ion molecules, polarized molecules, etc., vibrate more than 40,000 times per second, converting them into frictional heat to generate deep heat. The blood flow of capillaries increases 4-5 times more than at rest, increasing the supply of oxygen, nutrients, antibodies, and white blood cells. In addition, the electrochemical reaction does not occur because the vibration width and the pulsation period are very short. It is a physical factor treatment method that does not stimulate the sensory nerves and motor nerves. In this study, an isotonic exercise is performed in a young normal adult using a Radiofrequency pain treatment device. The purpose of this study is to integrate rehabilitation therapy by measuring electromyography data during isotonic exercise and confirming the effect on changes in motor neuron response. The EMG data generated when isotonic exercise of the forearm biceps muscle and the EMG data measured after the use of a Radiofrequency pain treatment device after exercise were RMS, respectively, and verified through t-test. It was confirmed that there was a significant difference in both men and women because the t-value was smaller than the significance level p (<.05).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.894-900
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• 2004

There are many types of circularly polarized(CP) microstrip antenna elements, which are used as a good unit radiator. Since an advantage of CP antenna is no strict alignment requirements between Rx and Tx system, the printed antennas with circular polarization are very often used in numerous satellite and mobile radio systems. In order to realize the broad bandwidth of 3 dB axial ratio and impedance of CP microstrip antenna, complex feed structure and tri-plate patch element have been researched. This paper describes a design of wideband microstrip cross slot array antennas with circular polarization. The proposed antenna is composed of an open-ended microstrip feed line as a feeder and a cross slot as a radiator for circular polarization. To realize the wide bandwidth, tri-plate structure are considered and cross slot is electromagnetically coupled with feed line. Optimum parameters of 1-element cross slot antenna are analyzed and designed by method of moments. These parameters are also applied to may antennas design considered the mutual coupling between radiating elements. Right hand circular polarization(RHCP) and left hand circular polarization(LHCP) of the proposed antenna are easily controlled by asymmetrical cross slot structure and slot position. In 1-element and 15-element cross slot array antenna, the good axial ratio of 1 dB below and the broad bandwidth characteristics of antenna are obtained.

• Strategy21
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• s.37
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• pp.104-143
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• 2015

China's new grand strategy, the "One Belt, One Road Initiative" (also Belt Road Initiative, or BRI) has two primary components: Chinese President Xi Jinping announced the "Silk Road Economic Belt" in September 2013 during a visit to Kazakhstan, and the "21^st Century Maritime Silk Route Economic Belt" in a speech to the Indonesian parliament the following month. The BRI is intended to supply China with energy and new markets, and also to integrate the countries of Central Asia, the Association of Southeast Asia Nations (ASEAN), and the Indian Ocean Region - though not Northeast Asia - into the "Chinese Dream". The project will be supported by the Asian Infrastructure Investment Bank (AIIB), due to open in 2016 with 57 founding members from all around the world, and China has already promised US$ 50 billion in seed funding. China's vision includes networks of energy pipelines, railways, sea port facilities and logistics hubs; these will have obvious commercial benefits, but also huge geopolitical significance. China seems to have two distinct aims: externally, to restore its historical sphere of influence; and internally, to cope with income inequalities by creating middle-class jobs through enhanced trade and the broader development of its economy. In South Korea, opinion on the BRI is sharply polarized. Economic and industrial interests, including Korea Railroad Corporation (KORAIL), support South Korean involvement in the BRI and closer economic interactions with China. They see how the BRI fits nicely with President Park Geun-hye's Eurasia Initiative, and anticipate significant commercial benefits for South Korea from better connections to energy-rich Russia and the consumer markets of Europe and Central Asia. They welcome the prospect of reduced trade barriers between China and South Korea, and of improved transport infrastructure, and perceive the political risks as manageable. But some ardently pro-US pundits worry that the political risks of the BRI are too high. They cast doubt on the feasibility of implementing the BRI, and warn that although it has been portrayed primarily in economic terms, it actually reveals a crucial Chinese geopolitical strategy. They are fearful of China's growing regional dominance, and worried that the BRI is ultimately a means to supplant the prevailing US-led regional security structure and restore the Middle Kingdom order, with China as the only power that matters in the region. According to this view, once China has complete control of the regional logistics hubs and sea ports, this will severely limit the autonomy of China's neighbors, including South Korea, who will have to toe the Chinese line, both economically and politically, or risk their own peace and prosperity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.84-91
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• 2002

The stochiometric composition of $AgGaS_2$/GaAs polycrystal source materials for the $AgGaS_2$/GaAs epilayer was prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns it was found that the polycrystal $AgGaS_2$/GaAs has tetragonal structure of which lattice constant an and Co were 5.756 $\AA$ and 10.305 $\AA$, respectively. $AgGaS_2$/GaAs epilayer was deposited on throughly etched GaAs(100) substrate from mixed crystal $AgGaS_2$/GaAs by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively. The crystallinity of the grown $AgGaS_2$/GaAs epilayer was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2$/GaAs epilayer at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by $\alpha=8.695{\times}10^{-4}$ eV/K, and $\beta=332K$. From the photocurrent spectra by illumination of polarized light of the $AgGaS_2$/GaAs epilayer, we have found that crystal field splitting ${\Delta}Cr$ was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Polymer(Korea)
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• v.28 no.4
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• pp.314-320
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• 2004

Soluble aromatic polyimides bearing 4-(4-oxyalkyleneoxystyryl)- pyridines (ethylene and hexylene) as photoreactive side groups were synthesized and characterized. The photoreactive polymers were soluble in various polar organic solvents and their films were easily formed by solution casting. The photoreactivities of the polymers in the film state were approximately 64% at an exposure energy of 1.5 J/$\textrm{cm}^2$. Transmittances of the polymer films were about 85% after annealing at 20$0^{\circ}C$. Therefore, these polymers can be evaluated to be photoreactive polyimides with good transparency and solubility. The dichroic ratios of the polymers with ethylene and hexylene groups as the alkylene spacers were 0.023 and 0.026, respectively. The order parameters of 4'-pentyl-4-bipheny1carbonitrile as a liquid crystal (LC) in the film cells of the former and latter polymers were 0.50 and 0.52, respectively. These results indicate that the polymers show the effect of alkylene spacer on the photoalignments. The LC in the film cells of the polymers was perpendicularly oriented to the electric vector of the linear polarized UV light (LPUVL).

• Polymer(Korea)
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• v.35 no.4
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• pp.350-355
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• 2011

A soluble polyamide containing photosensitive l,4-phenylenediacrylic acid (PDA) in main chain with biphenyl moiety was synthesized. The chemical structure of synthesized polyamide was investigated by means of $^1H$ NMR spectroscopy. The polymer was stable up to $280^{\circ}C$ and soluble in organic solvents, giving a good quality of thin films. The photoreaction of unpolarized LTV irradiated films was investigated by means of UV-vis absorption spectroscopy and FTlR spectroscopy, and liquid crystals (LCs) alignment property was examined by exposing to linearly polarized UV light (LPUVL) of 260~380 nm. The polyamide in film has excellent photoreactivity to unpolarized UV light. Direction selective photoreaction of PDA moiety in Lhe film was found to further induce nematic liquid -crystals to align along a perpendicular direction with respect to the electric vector of LPUVL, regardless of exposure energy of LPUVL. In addition, pretilt angle was measured by means of crystal rotation method. LPUVL-exposed polymer film induced the alignment of liquid-crystals (LC) with a pretilt angle of 0.2~$0.5^{\circ}$.