• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.125-131
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• 2021

For the vibration reliability tests, the jigs for mounting the test specimen on a vibration reliability tester are required. The dynamic stabilities of the jigs should be verified before the tests for obtaining the accurate reliability of the test specimen. This paper proposes an analytical technology for ensuring the dynamic structural stability for the test setup including the jig. The technology includes the mode analyses for checking resonance, the harmonic analyses for evaluating the dynamic structural stability of test setup including the jig, and the fatigue analyses for obtaining the durable reliability time with calculating the life cycles at the area of weakness. The cause investigation of the damaged jig during vibration reliability test of a rubber hose and the design of new revised jig are performed by using the technology. The vibration reliability test for the rubber hose with the new revised jig by analysis results is successfully conducted without any problem. Therefore the jig's design technology proposed in this paper may be useful for other items as well.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.301-306
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• 1999

Hepatitis C virus (HCV) has been known to be an enveloped virus with a positive strand RNA genome and the major agent of the vast majority of transfusion associated cases of hepatitis. For viral replication, HCV structural proteins are first processed by host cell signal peptidases and NS2/NS3 site of the nonstructural protein is cleaved by a zinc-dependent protease NS2 with N-terminal NS3. The four remaining junctions are cleaved by a separate NS3 protease. The solution conformations of NS4B/5A, NS5A/5B substrates and NS5A/5B inhibitor have been determined by two-dimensional nuclear magnetic resonance (NMR) spectroscopy. NMR data suggested that the both NS5A/5B substrate and inhibitor appeared to have a folded tum-like conformation not only between P1 and P6 position but also C-terminal region, whereas the NS4B/5A substrate exhibited mostly extended conformation. In addition, we have found that the conformation of the NS5A/5B inhibitor slightly differs from that of NS5A/5B substrate peptide, suggesting different binding mode for NS3 protease. These findings will be of importance for designing efficient inhibitor to suppress HCV processing.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.40.3-40.3
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• 2019

Our recent observations of the Sun through strong spectral lines have revealed several important properties of the three-minute umbral oscillations inside sunspots -- the oscillations of intensity and Doppler velocity with periods of 2 to 3 minutes. The oscillations usually occur in the form of a time series of oscillation packets each of which lasts 10 to 20 minutes, not as continuous trains. Each oscillation packet is characterized by a singly peaked power spectrum of velocity oscillation. The oscillations propagate in the vertical direction from the photosphere to the corona. In the upper chromosphere, they develop into shocks that eventually collide with the transition region. When shocks propagate along a highly inclined direction, the merging of two successive shocks can take place. Once they enter the corona, they change to linear compressional waves. In the image plane, the three-minute oscillations propagate with high speeds in the transverse direction as well, usually propagating radially outwards from a point, and sometimes accompanying spiraling patterns of Doppler velocity. These observational properties can be theoretically explained by postulating the spatio-temporally localized source of fast MHD waves at a depth of about 2000 km below the surface, the excitation of slow MHD waves via mode conversion near the photosphere, and the resonance of the slow waves in the photospheric layer below the temperature minimum, and the nonlinear development of slow waves in the chromosphere.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.155-160
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• 2024

The polarization-selective beam splitter grating can be widely used in numerous optical information processing systems. In this paper, to design a high-efficiency plasma polarization beam splitter (PBS), the structure composed of an Ag metal layer in Littrow mounting is implemented. To achieve high diffraction efficiency in the transmitted 0th-order TE polarization and the reflected 0th-order TM polarization, the grating depth and grating ratio of presented PBS is optimized by using rigorous Modal Transmission-Line Theory. From the optimized results, PBS has advantages of wide band properties for incident wavelength and angle, and the efficiency is higher than 95% for both TE and TM polarization. Therefore, this highly efficient PBS wideband grating with high extinction ratio can be used as an excellent optical diffraction device.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.1-6
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• 2023

Dendranthema zawadskii is a one of the popular plants as native in South Korea. In this study, linarin was isolated and purified using silica-gel, Diaion, and Sephadex LH-20 from the aerial parts of D. zawadskii. The chemical structure was completely identified through spectroscopic data including 1D, 2D nucleic magnetic resonance, and HRFABMS. Furthermore, linarin inhibited the bacterial neuraminidase (BNA) activity with 13.5 μM of IC₅₀ dose-dependently. Through the enzyme kinetic experiments, linarin as BNA inhibitor exhibited a typical noncompetitive inhibition mode which K_m was contestant and V_max decreased as the concentration of the inhibitor increased. It was further identified that the inhibition constant was 16.0 μM. Linarin was the most abundance metabolite in the aerial part of D. zawadskii extract by UHPLC-TOF/MS analysis. Therefore, D. zawadskii and its main component are expected that it can be effectively used for the infection and inflammation caused by bacteria.

• Korean Journal of Materials Research
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• v.10 no.3
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• pp.212-217
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• 2000

Dielectric thin films for TFT(thin film transistor)s, such as silicon nitride$(Si_3N_4)$ and silicon oxide$(SiO_2)$, are usually deposited at $200~300^{\circ}C$. In this study, authors have tried to form dielectric films not by deposition but by oxidation with ECR(Electron Cyclotron Resonance) oxygen plasma, to improve the interface properties was not intensionally heated during oxidation. THe oxidation was performed consecutively without breaking vacuum after the deposition of a-Si: H films on the substrate to prevent the introduction of impurities. In this study, especially pulse mode of microwave power has been firstly tried during FCR oxygen plasma formation. Compared with the case of the continuous wave mode, the oxidation with the pulsed ECR results in higher quality silicon oxide$SiO_X$ films in terms of stoichiometry of bonding, dielectric constants and surface roughness. Especially the surface roughness of the pulsed ECR oxide films dramatically decreased to one-third of that of the continuous wave mode cases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.69-75
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• 2017

In this paper, slit ground resonator with slit and capacitor is proposed for practical use of magnetic resonant wireless power transfer(MR-WPT). And this paper presents the performance comparison of conventional loop resonator as Rx resonator to slit ground resonator. The proposed silt ground resonator with 31 cm width, 20.5 cm length, $35{\mu}m$ thickness is designed the crossing slit 1 cm width with only opened edge. And an external capacitors were connected at the opened edge of slit ground resonator for resonating at 6.78 MHz. The transfer efficiencies of MR-WPT were measured at open and short mode, and then the highest transfer efficiencies of MR-WPT according to the Rx resonators were plotted. In result, the transfer efficiency of MR-WPT with loop resonator was the highest. However, when the ground was inserted in receiver part at the bottom of laptop model, the transfer efficiency was closed 0 %. The transfer efficiency recovered the transfer efficiency of 67 % using slit ground resonator. The magnetic field was penetrated through the slit and proposed slit ground resonator works as resonator in MR-WPT.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.58-60
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• 2007

Magnetic Resonance Imaging(MRI) has become a very widely used medical procedur e. Clo.sed and open systems are typically used with static magnetic fields at or below 2 Tesla. BWhole body SAR(specific absorbsion rate) is the value of SAR averaged over the entire body of the patient over any period of 15 minutes. Head SAR is the value of SAR averaged over the head of the patient for any period of 10 minutes. SAR is a measure of the absorption of electromagnetic energy in the body' (typically in watts per kilogram (W/kg)). The normal operating mode comprises values of head SAR not higher than 3 W/kg. The second level controlled operating mode comprises values higher than 3 W/kg. Current FDA guidance limits the SAR in the whole body. including the head to a range of 1.5 to 4.0 W/kg, depending on the patient's clinical condition. SAR, limit restrictions are incorporated in all MRI systems. and domestic' s guidance limits the SAR in a part body. including the head to 3.2w/kg and less. The purpose of this study is to evaluate on change of head SAR in using MRI pulse sequence and to check if exceed 3.2(w/kg) level in domestic a part exposure through measured head SAR. 23 patient's the average head SAR of pulse sequence is that T2WI sagittal is 0.5375. T2WI axial(FSE) is 0.4817, T1WI axial(SE) is, 0.8179. FLAIR axial is 0.4580. GRE axial is 0.0077, Diffusion is 0.0824w/kg. The head SAR exposed per patient was proved 2.3845w/kg less than the international standard. Coefficient of correlation for the relations body weight and SAR or for the relations ETL(echo train length) and SAR is 1 value. Coefficient of correlation for the relations between TR(time to repeat) and SAR is -0.602 value. so SAR increased relative to weight body and ETL. But the relations between TR and SAR is negative definite.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.23 no.2
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• pp.57-62
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• 2012

Objectives : Characteristic symptoms, including hyperactivity and easy distractibility, in children with attention-deficit hyperactivity disorder (ADHD) suggest that their brain status, even at rest, might differ from that of healthy children. This study was conducted in order to determine whether resting state brain activity is compromised in medication-naive children with ADHD. Methods : Twenty medication-naive children with ADHD (mean age $10.3{\pm}2.5$) and 28 age- and gender-matched healthy volunteers (mean age $10.3{\pm}2.0$) underwent measurements for resting state brain activity using functional magnetic resonance imaging (fMRI). Among resting state related-independent components (RSICs) extracted from fMRI data using independent component analysis, a significant difference in RSICs was observed between groups, using a mixed Gaussian/gamma model. Results : Except for IQ, which was higher in the healthy control group, no demographic difference was observed between the two groups (p<.001). Significantly less activation of one RSIC, which includes the bilateral precuneus/posterior cingulate cortex, occipito-temporal junction, and anterior cingulate cortex, was observed in the ADHD group, compared with the control group (p<.05). Conclusion : An abnormal RSIC, posterior default mode network (DMN), was observed in the medication-naive ADHD group. Results of our study suggest that abnormality of posterior DMN is one of the main pathophysiologies of ADHD.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.775-782
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• 2022

In this paper, a novel small-diameter cylindrical post capacitor inserted into an evanescent-mode rectangular waveguide (EMRWG) is proposed for easier tuning. In order to feed the EMRWG, the proposed structure uses a single ridge rectangular waveguide with the same width and height as the waveguide at the input and output ends. The inserted post capacitor are made up a circular groove formed in the center of the lower part of the broad wall of the EMRWG, and a concentric cylindrical post inserted into the upper part. First, the equivalent circuit model for the proposed structure is presented. When the EMRWG and the single ridge waveguide are combined, the joint susceptance and the turns ratio of the ideal transformer are calculated by two simulations using HFSS (3d fullwave simulator, Ansoft Co.) respectively. The susceptance and resonance characteristics of the inserted post were analyzed by using the obtained parameters and the characteristics of the EMRWG. A 2-post filter with a center frequency of 4.5 GHz and a bandwidth of 170 MHz was designed using a WR-90 waveguide, and the simulation results by using the HFSS and CST, equivalent circuit model were in good agreement.