• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.892-899
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• 2013

This paper discusses difficulties in precise measurements of the scattering parameters in (sub-)millimeter-wave range and tips for more accurate measurements, and provides measurement examples in the G-band(140~220 GHz). First, one investigates the differences in operating principles of scattering parameters measurement systems used in microwave and (sub-)millimeter-wave ranges and describes tips for better operation of the (sub-)millimeter-wave scattering parameters measurement system. In addition, one describes tips for better transmission properties and connection repeatability of waveguides and a precise measurement method for devices with small reflection coefficients.

• The Journal of Korean Academic Society of Nursing Education
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• v.24 no.4
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• pp.326-336
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• 2018

Purpose: This study was conducted to identify the factors affecting nursing students' attitudes toward nurse-physician collaboration. Methods: The subjects were 200 nursing students from a college in K city, and the participants were recruited by posting a recruitment announcement. Data were collected from June 26 to 29, 2018 and analyzed using SPSS 22.0 and descriptive statistics, t-test, ANOVA, Sheff? test, Pearson's correlation coefficients, and hierarchical multiple regression. Results: Attitudes toward nurse-physician collaboration showed a statistically significant difference according to grade, the reflection of opinion within the family, and the number of the counselor in general characteristics. Assertiveness and attitudes toward nurse-physician collaboration showed weak positive correlation (r=.18, p=.011). In hierarchical multiple regression analysis, the most affecting factor was junior grade (${\beta}=.25$), followed by positive assertiveness (${\beta}=.18$) and the number of the counselor (${\beta}=.14$). These variables explained 12.0% of the total variance in attitudes towards nurse-physician collaboration. Conclusion: To create positive attitudes toward collaboration between nurses and physicians in nursing students, various educational programs related to assertiveness on communication skills need to be provided from the lower grades. Also, a multidisciplinary simulation program should be developed and applied to be able to experience the situation of nurses and physicians.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.515-519
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• 2015

In this paper, we suggested the novel monopole antenna for dual band characteristics by a linear monopole antenna combined with crossed planar monopole antenna. The target frequency is ISM(Industrial Scientific Medical) 2.45GHz/5.8GHz. The distinctive features of the proposed antenna in this paper is based on the slit in the surface of a crossed planar monopole for the dual band characteristics and the omnidirectional radiation patterns. The compact size of the proposed antenna is $36mm{\times}5.4mm{\times}5.4mm$. According to the simulation results, the bandwidth, the reflection coefficients below -10dB, of 2.45GHz and 5.8GHz are 150MHz and 1.43GHz, respectively. Consequently the proposed antenna structures is apply to the antenna for dual band characteristics.

• Korean Journal of Optics and Photonics
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• v.10 no.3
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• pp.188-194
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• 1999

We synthesized the nonlinear optical (NLO) PI-SOT(polyimide system, 4-[N,N-bis(hydroxyethyl)amino-4,-($\beta$-cyano-$\beta$-methylsulfonyl)vinyl]azobenzene) polymer with high electro-optic coefficients as well as good thermal and temporal stabilities of the elector-optic coefficient ${\gamma}_33$ by the simple Mitsunobu reaction. By using the simple reflection method of C. C. Teng, we measured the thermal and temporal stabilities of the electro-optic coefficient ${\gamma}_33$ of corona-poled PI-SOT polymer at the wavelength of 632.8 nm and 852 nm, respectively. At the temperature of $20^{\circ}C$, the electro-optic coefficient ${\gamma}_33$ of corona-poled PI-SOT polymer were 25.12 pm/V at the wavelength of 632.8 nm and 5.40 pm/V at the wavelength of 852 nm. These values were highly stabilized for more than 60 days at 2$0^{\circ}C$ and stabilized within 6% for more than 10 hours at $100^{\circ}C$.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.155-160
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• 2004

Permeation experiments of a commercial nanofiltration membrane (nominated as ESNA 1) were carried out with aqueous solutions of various single salts, that is, five chlorides (NH$_4$Cl, NaCl, KCl, MgCl$_2$ and $CaCl_2$), three nitrates $(NaNo_3,\;Mg(No_3)_2\;and\;Ca(NO_3)_2)\;and\;three\;sulfates\;((NH_4)_2SO_4,\;Na_2SO_4\;and\;MgSO_4)$. The experimental results showed that (1) the permeate volume flux of the ESNA 1 membrane increased and decreased with the growth of the applied pressure and the feed concentration of salts, respectively. The real rejection of ESNA 1 membrane to most single salts increased with the growth of the permeate volume flux. (2) The reflection coefficients of ESNA 1 membrane to chlorides, nitrates and sulfates are 0.97, 0.96 and 0.99, respectively. The solute permeability of most salts except for magnesium and calcium salts increased with the growth of feed concentration. (3) The sequence of the rejections of ESNA 1 membrane to anions is $R({SO_4}^{2-})>R(CI)>R(NO_3)$ at the same feed concentration. While the sequence of the rejections to cations is cataloged into two cases: $R(Na^+)>R(K^+)>R(Mg^{2+})>R(Ca^{2+})$ at the concentration of 10 mol/$m^3$ and $R(Mg^{2+})>R(Ca^{2+})>R(Na^+)>R(K^+)$ at the concentration of 100 mol/$m^3$. The separation capability of a NF membrane is usually affected by the electrostatic effect and the steric-hindrance effect. In this case, the electrostatic effect is the major factor at low concentration and the steric-hindrance effect is the major factor at high concentration. Both the specific sorption and the hydration also reasonably influenced the separation performance of NF membrane to salts.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1044-1052
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• 1999

A 2-stage 1 watt MMIC(Monolithic Microwave Integrated Circuits) HPA(High Power Amplifiers) at 20 GHz band has been designed and fabricated. The $0.15\mu\textrm{m}$ with the width of $400\mu\textrm{m}$for single device pHEMT technology was used for the fabrication of this MMIC HPA. Due to the series feedback technique from source to ground, bias circuits and stabilization circuits on the main microstrip line, the stability factors(Ks) are more than one at full frequency. The independent operation for each stage and excellent S11, S22 less than -20 dB have been obtained by using lange couplers. For beginning the easy design, linear S-parameters have been extracted from the nonlinear equivalent circuit in foundry library, and equivalent circuits of devices at in/output ports were calculated from this S-parameters. The measured performances, which are in well agreement with the predicted ones, showed the MMIC HPA in this paper has the minimum 15 dB of linear gain, -20 dB of reflection coefficients and 31 dBm of output power over 17~25 GHz.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.193-203
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• 1996

Long period waves were measured at two stations outside and inside Chukpyon Harbor using two pressure-type wave gauges for one week that covers storm sea period. Based on the collected data the characteristics of long-period resonant oscillations were analysed: the resonant period corresponding to the peak spectral density are slightly different from one to the component wave period with the largest amplification ratio, and the latter period is suggested as that of the first resonant mode. From the analysed field data and numerical modeling, the first resonant mode of Chukpyon Harbor region appeared to be around 12 minutes with amplification ratio of 7, whose amplitude varies 10-20 cm inside of the harbour, and also the second mode appeared to be around 6 minutes. The waves of 2-3 minute periods were resonated apparently in the harbour, which is considered to be generated from group-bounded irregular waves and non-linear wave-wave interaction etc. The linearly decreasing reflection coefficients used in the numerical modeling appeared to be an alternative in calculating reflected waves in harbor.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.473-478
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• 2015

In this paper, we suggest a flexible multiband antenna which can be equipped on an inflatable life-jacket. The antenna can send distress alert and location data of survivors to assist rescue operation when crew or people are in distress. The antenna operate in three frequency bands such as VHF-DSC band (156MHz), COSPAS-SARSAT band (406MHz) and GPS band (1,575MHz). The GPS band is implemented with a square ring-slot planar antenna, the COSPAS-SARSAT band and the VHF-DSC band antenna is implemented by monopole type. In order to give flexibility of substrate to be equipped on life-jacket, FR4-epoxy substrate of thickness 0.2mm is used to make antenna. The reflection coefficients of the fabricated antenna are -8.8dB, -20.4dB and -10.7dB at each bandwidth like VHF-DSC, COSPAS-SARSAT and GPS band, respectively, when people are wearing life-jacket integrated multiband antenna.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.68-75
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• 2019

A low-crested structure (LCS) is an excellent feature not only because it provides shore protection but also because it is fully submerged. However, in order to properly control waves, it is necessary to maintain a certain range of crest height and width in consideration of the wave dimensions at the installation area. According to previous studies, an LCS has some wave breaking effect when the crest width is more than a fourth of the incident wavelength and the crest depth is less than a third of the incident wave height. In other words, if the crest width of the LCS is small or the crest depth is large, it cannot control the wave. Therefore, when an LCS is installed in a large sea area with a great tidal range in consideration of the landscape, waves cannot be blocked at high tide. In this study, the hydraulic performances of a typical trapezoidal LCS with a constant crest height and a low-crested structure with an adjustable crest height, which was called a tide-adapting low-crested structure (TA-LCS) in this study, were compared and evaluated under various wave conditions through hydraulic experiments. It was found that the wave transmission coefficients of the TA-LCS at high tide were lower than the values for the typical LCS based on empirical formulas. In addition, the hydraulic performances of the TA-LCS for wave reflection control were 12.9?30.4% lower than that of the typical LCS. Therefore, the TA-LCS is expected to be highly effective in controlling the energy of incoming waves during high tide even in a macro-tidal area.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.995-1010
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• 2020

In this study, a multivariate analysis model of partial least square regression (PLSR) was developed to predict the moisture content of green peppers using hyperspectral imaging (HSI). In HSI, illumination is essential for high-quality image acquisition and directly affects the analytical performance of the visible near-infrared hyperspectral imaging (VIS/NIR-HSI) system. When green pepper images were acquired using a direct lighting system, the specular reflection from the surface of the objects and their intensities fluctuated with time. The images include artifacts on the surface of the materials, thereby increasing the variability of data and affecting the obtained accuracy by generating false-positive results. Therefore, images without glare on the surface of the green peppers were created using a polarization filter at the front of the camera lens and by exposing the polarizer sheet at the front of the lighting systems simultaneously. The results obtained from the PLSR analysis yielded a high determination coefficient of 0.89 value. The regression coefficients yielded by the best PLSR model were further developed for moisture content mapping in green peppers based on the selected wavelengths. Accordingly, the polarization filter helped achieve an uniform illumination and the removal of gloss and artifact glare from the green pepper images. These results demonstrate that the HSI technique with a polarized lighting system combined with chemometrics can be effectively used for high-throughput prediction of moisture content and image-based visualization.