• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.213-219
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• 2007

In this paper, A novel structure of frequency doubler using Phase Delay line and $90^{\circ}$ Hybrid coupler at harmonic output have been designed and implemented to improve suppression. Proposed structure of frequency doubler improve output. coupling and fundamental suppression. Active frequency doubler with band from $2.13{\sim}2.15GHz\;to\;4.26{\sim}4.3GHz$ was designed and fabricated with 10dBm input power, 0.79dB conversion gain and -55.54dBc suppression at fundamental frequency, -44.76dBc suppression at third harmonic frequency 6.42GHz and -39.18dBc suppression at fourth harmonic frequency 8.56GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.7
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• pp.631-638
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• 2009

In this paper, a wide-band monopole antenna for use in PCS/WDCMA/Wivro/S-DMB(1.750${\sim}$2.655 GHz) band is presented. The presented antenna is a trapezoidal monopole antenna which has back-side patch and improves the bandwidth. To confirm the wide-band characteristics and radiation pattern of presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 2 dBi in 1.73${\sim}$3.48 GHz. The measured results show good agreement with calculated results. From the result, we confirm that the designed antenna can be used indoor antenna for PCS/WCDMA/WiBro/S-DMB.

• Journal of Mushroom
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• v.5 no.1
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• pp.21-24
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• 2007

A new variety of oyster mushroom 'Choengsan' was developed with crossing between monokaryotic strains derived from Suhan and Wonhyoung #3. It was developed by Agriproduct Processing Experiment Station, Gangwon Agricultural Research & Extension Services in 2006. The optimum temperature of mycelial growth was around $27{\sim}28^{\circ}C$ and that of fruiting body was $14{\sim}17^{\circ}C$. The color of pileus was dark-gray color. The period of primordial occurrence was about 20 days in bed cultivation using cotton waste and the yields were $38kg/3.3m^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.800-806
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• 2008

In this paper, a wide-band dipole antenna suitable for use in PCS/WCDMA/WiBro($1.750{\sim}2.39\;GHz$) base station array antenna is presented. The presented antenna is a dipole antenna with pate which has the reflector element and improves the gain flatness. To confirm the wide-band characteristics and the gain flatness of the presented antenna, the experimental antenna is fabricated and its radiation characteristics are measured, compared with calculated results. It is shown that the designed antenna has VSWR less than 1.5, gain over 5 dBi, and gain flatness 0.74 dB in $1.75{\sim}2.39\;GHz$. The measured results show good agreement with the calculated results. From these results, we confirm that the designed antenna can be used as a array element of the wide-band base station array antenna for PCS/WCDMA/WiBro.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.33-39
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• 2008

In this paper, a broadband rectangular reflector antenna with 16-array elements for WiBro/WiMAX band(2.3${\sim}$3.5 GHz) is designed, and its radiation characteristics are investigated. The designed antenna is composed of the IBBD(Integrated Balun Bow-tie Dipole) elements and has the feed circuit at the rear of the reflector to reduce the unwanted electromagnetic wave from it. To confirm the broadband characteristics of the designed antenna, test antenna is fabricated and its radiation characteristics are measured, compared with calculated results. The measured results show good agreement with the calculated results. As a result of measurements, 1.8GHz of bandwidth(VSWR<1.6) is achieved at $2.06{\sim}3.89GHz$ and the antenna gain over 10.3 dBi. We confirm that the designed antenna can be used as a broadband antenna for WiBro/WiMAX.

• Korean Journal of Medicinal Crop Science
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• v.9 no.1
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• pp.76-82
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• 2001

This study was conducted to find out the optimum ranges of soil physical properties for wasabi growth by the relationship of soil physical properties and plant growth. Soil bulk density and hardness were higher in decomposition of granite and river sand than hydroball. This root distribution of surface layer was higher in decomposition of granite and river sand than hydroball. Growth characteristics and yield were higher in hydroball than decomposition of granite and river sand. In inlet site, the marketable rhizome weight in decompasition of granite, river sand, hydroball were 298kg/10a, 401kg/10a, 766kg/10a, respectively. But outlet, the weight in three soils were 251kg/10a, 256kg/10a, 633kg/10a, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.233-240
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• 2007

In this paper, the broadband cross monopole antenna is presented and the radiation characteristics are investigated. The presented broadband cross monopole antenna is composed of the cross monopole element and the folded short stub, which has a excellent band characteristics more than the existing cross monopole antenna. To conform the broadband characteristics of the presented antenna, the experimental antenna is designed, fabricated, and its radiation characteristics are measured in $1.75\sim2.655\;GHz$. It is shown that the designed antenna has the nondirectional pattern in the horizontal plane, the directional pattern in the vertical plane, VSWR less than 1.5, and gain in $2.17\sim4.87\;dBi$. From these results, the presented antenna is conformed as a broadband indoor antenna which can be used for PCS, WCDMA, Wibro, and satellite DMB band.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.57-65
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• 2005

When arch ribs are subjected unsymmetrical load, buckling strength Is lower than strength of arch ribs subjected symmetrical load. However, A few study about the buckling strength of arch ribs subjected unsymmetrical load is performed compare with study about arch ribs subjected symmetrical load. Several researchers(Deutch : 1940, Chang : 1973, Harrison : 1982) studied about arch ribs subjected unsymmetrical load and they found that unsymmetrical loading reduces the critical buckling load. But, their results are limited parabolic arch ribs. This paper focuses on circular arch ribs subjected to unsymmetrical loading. The result shows that the ratio of live and dead load length to cause smallest critical buckling load of arch ribs is $0.6{\sim}0.7$ under geometric nonlinear condition and $0.5{\sim}0.6$ under both material and geometrical nonlinear conditions.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.434-441
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• 2009

The effect of varying sulfate concentration on continuous fermentative hydrogen production was studied using enriched mixed microflora in continuously fed reactor. Glucose was used as a model substrate for carbohydrates, and hydraulic retention time (HRT) was maintained at 1, 0.5, 0.25 day, respectively. Sulfate concentration was 0${\sim}$20,000 mg/L and the operating pH was maintained at 5.5. The experimental results indicate that hydrogen production is not affected by high sulfate concentration and shorter HRT of 0.25 day enhance hydrogen production. At HRT 1, 0.5, 0.25 day, the hydrogen production rate and hydrogen yield were 2.6, 4.6, 9.4 L/day, and 2.0, 1.8, 1.6 mol $H_2$/mol glucose, respectively. Residual sulfate content was 96${\sim}$98, 95${\sim}$97, and 94${\sim}$97% at HRT 1, 0.5, 0.25 day which show that no sulfate reduction occurred in the reactor during the experiments. Results of Fluorescence In Situ Hybridization (FISH) may indicate the presence of HPB (hydrogen producing bacteria) under all experimental conditions. However, SRB (sulfate reducing bacteria) were not found.

• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.194-199
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• 2002

Eight Korean wheat cultivars were milled and evaluated for the properties of white layer cake-making, compared to a commercial soft wheat flour. Milling yields of the Korean wheat cultivars ranged from 62.5 to 71.8%. The protein and ash contents of flours milled from Korean wheat cultivars ranged from 7.70 to 10.58% and 0.51 to 0.71%, respectively. Woorimil, Alchanmil and Olgeurumil flours, having low protein content, showed very weak mixing characteristics. Even though Eunpamil and Geurumil flours showed longer mixing time and higher peak height, they had week dough stability. Slight differences in pH and specific gravity of cake batter were observed among the Korean wheat flours. Cake volume measured by rapeseed displacement was in the range of $837.5{\sim}952.5\;cc$. Alchanmil flour demonstrated the highest specific volume of 2.40, and the other domestic flours symmetrical and uniform than those with the commercial soft wheat flour. Volume of white layer cakes was negatively affected by flour protein content and somewhat associated with crumb softness. Crumb color of cakes prepared with domestic wheat flours was slightly darker and more yellowish. Hardness of fresh cakes prepared with domestic flours ranged from 307.33 to 416.60 $g_f$.