• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.36-41
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• 2018

This paper presents an implementation of a millimeter-wave(W band) multiflare-angle horn antenna. The proposed antenna is a multimode dual-polarized square horn having equal E- and H-plane beamwidths and consists of a multimode generating section, a four-square-waveguide exciter, orthomode transducers, and power combiners for the sum pattern formation. The antenna structure has been designed to allow for easy fabrication and the designed antenna has been fabricated to a precision of ${\pm}0.02mm$ by layer-by-layer machining and diffusion bonding. The input reflection coefficient and the radiation pattern of the fabricated antenna have been measured using a network analyzer and a far-field test facility. Measurements show that the proposed antenna has 17.7~18.3 dBi gain, $25.2{\sim}28.5^{\circ}$ beamwidth, and an input VSWR between 1.02~1.75, within ${\pm}0.5GHz$ from the center frequency.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.68.1-68.1
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• 2014

We present the results of far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS) on board the Korean microsatellite STSAT-1, which operated at an altitude of 700 km in a sun-synchronous orbit. FIMS is a dual channel imaging spectrograph (S-channel 900-1150 ${\AA}$, L-channel 1350-1710 ${\AA}$, and ${\lambda}/{\Delta}{\lambda}$ ~ 550 for both channels) with large image fields of view (S-channel $4.0^{\circ}{\times}4.6^{\prime}$, L-channel $7.5^{\circ}{\times}4.3^{\prime}$, and angular resolution ~ $5-10^{\prime}$) optimized for the observation of diffuse emission of astrophysical radiation. Comet C/2001 Q4 (NEAT) were made in two campaigns during its perihelion approach between May 8 and 15, 2004. Based on the scanning mode observations in the wavelength band of 1400-1700 ${\AA}$, we have constructed an image of the comet with an angular size of $5^{\circ}{\times}5^{\circ}$, which corresponds to the central coma region. Several important fluorescence emission lines were detected including S I multiplets at 1429 and 1479 ${\AA}$, C I multiplets at 1561 and 1657 ${\AA}$, and the CO $A^1{\Pi}-X^1{\Sigma}^+$ Fourth Positive system; we have estimated the production rates of the corresponding species from the fluxes of these emission lines. The estimated production rate of CO was $Q_{CO}=(2.65{\pm}0.63){\times}10^{28}s^{-1}$, which is 6.2-7.4% of the water production rate and is consistent with earlier predictions. The average carbon production rate was estimated to be $Q_C={\sim}1.59{\times}10^{28}s^{-1}$, which is ~60% of the CO production rate. However, the observed carbon profile was steeper than that predicted using the two-component Haser model in the inner coma region, while it was consistent with the model in the outer region. The average sulfur production rate was $Q_S=(4.03{\pm}1.03){\times}10^{27}s^{-1}$, which corresponds to ~1% of the water production rate.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.214-226
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• 1992

In this paper, the characteristics of fatigue crack growth in the spot welded joint of the same kinds of specimens($HS{\times}HS,\;GA{\times}GAB$) and different kinds of specimens($HS{\times}GA,\;HS{\times}GAB$) which consist of dual phase high strength steel(HS) and monogalvanized steel(GA) were examined with static tension tests and axial tension fatigue tests. Some of the important results are as follows : 1. The divergence of tensile strengths among the same and different kinds of spot welds under the same conditions is comparatively low regardless of the difference of stiffness. 2. At the low load bevel and long life legion, the fatigue crack is initiated near the nugget. However, in the high load level and short life region, it occurs a tittle far from the nugget. 3. It has shown a linear relation between maximum stress Intensity factor, Kmax and fatigue life, $N_f$ among each of the spot welds and has gathered in a narrow band on the log-log graph paper. $Kmax=H{\cdot}{N_f}^{P}$ where H and P are a material constant.

• KSBB Journal
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• v.11 no.3
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• pp.295-302
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• 1996

The measurements of rubisco parameters are important in photosynthetic studies. In this experiment, we used photometric assay method to detect these major parameters, such as activity, carbamylation and amount of rubisco. The main advantages of this method are very simple and as sensitive as conventional methods which usually produce radioactive waste. In this study, with kidney bean (Phaseolus vulgatis L.) leaves grown at normal $CO_2$ (350ppm) and high $CO_2$ (650 ppm), we investigated the effect of $CO_2$ concentration on activation and carbamylation of rubisco by measuring the rubisco activity, carbamylation rate and amount of rubisco using a dual beam (334nm and 405nm) spectrophotometer, and analyzed the polypeptide profiles of rubisco by SDS-PAGE. When $CO_2$ concentration was raised from 350ppm to 650ppm, all parameters of rubisco were decreased : $41.2{\mu}M/m^2/s and 52.2{\mu}M/m^2/s$ to $27.4{\mu}M/m^2/s and 46.1{\mu}M/m^2/s$ for initial and total rubisco activity, respectively ; from 79% to 58.9% for carbamylation rate ; from $1.94 {\mu}M/m^2$ to 1.58{\mu}M/m^2$ for amount of rubisco. These results suggests that the decrease in rubisco activity at high $CO_2$ was caused by carbamylation. The analysis of the preparation by SDS-PAGE showed two major polypeptides at 50 and 14.5 kD which were identified as the large and the small subunits of rubisco. There were no differences in the intensity compared high $CO_2$ to normal $CO_2$ in both 50 kD and 14.5 kD bands. We also found that these inhibitory effects of $CO_2$ were reversible. When high $CO_2$ was switched to normal $CO_2$, the parameters of rubisco changed were almost the same as normal rubisco parameters. These data provide an evidence that activity of rubisco was recovered by $CO_2$ concentration of 350 ppm.