• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.282-285
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• 1999

The (1-x)MgTiO$_3$-xSrTiO$_3$(x=0,0.1) ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and DT-TGA. Increasing the sintering temperature from 130$0^{\circ}C$ to 1$600^{\circ}C$, second phase was decreased and grain size was increased. In the case of 0.9 MgTiO$_3$-0.1SrTiO$_3$ ceramics sintered at 130$0^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 22.61, 10,928(at 1GHz), +50.26ppm/$^{\circ}C$ , respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.23-31
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• 2013

Microwave remote sensing can help monitor the land surface water cycle and crop growth. This type of remote sensing has great potential over conventional remote sensing using the visible and infrared regions due to its all-weather day-and-night imaging capabilities. In this paper, a ground-based multi-frequency (L-, C-, and X-band) polarimetric scatterometer system capable of making observations every 10 min was developed. This system was used to monitor the wheat over an entire growth cycle. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. Backscattering coefficients for the crop growing season were compared with biophysical measurements. Backscattering coefficients for all frequencies and polarizations increased until dat of year 137 and then decreased along with fresh weight, dry weight, plant height, and vegetation water content (VWC). The range of backscatter for X-band was lower than for L- and C-band. We examined the relationship between the backscattering coefficients of each band (frequency/polarization) and the various wheat growth parameters. The correlation between the different vegetation parameters and backscatter decreased with increasing frequency. L-band HH-polarization (L-HH) is best suited for the monitoring of fresh weight (r=0.98), dry weight (r=0.96), VWC (r=0.98), and plant height (r=0.96). The correlation coefficients were highest for L-band observations and lowest for X-band. Also, HH-polarization had the highest correlations among the polarization channels (HH, VV and HV). Based on the correlation analysis between backscattering coefficients in each band and wheat growth parameters, we developed prediction equations using the L-HH based on the observed relationships between L-HH and fresh weight, dry weight, VWC and plant height. The results of these analyses will be useful in determining the optimum microwave frequency and polarizations necessary for estimating vegetation parameters in the wheat.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.476-482
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• 2006

In this paper, a multimode feed horn antenna is suggested for a high power microwave(HPM) antenna system. The proposed HPM feed horn antenna which is connected with a mode converter is located between source and reflector antenna. A multimode feed horn antenna which has reduced -25 dB beamwidth is designed and fabricated for miniaturization of reflector antenna because -25 dB beamwidth which is determined by considering spillover of feed horn antenna decides a size of reflector in case of HPM. As a result, feed system which uses the multimode feed horn antenna has high gain about 27 dBi and return loss is less than -22 dB at 10 GHz. The measured -25 dB beamwidths of the radiation pattern at vertical, horizontal-plane equal to $20.24^{\circ},\;28.92^{\circ}$ which is less than about $10^{\circ}$ beamwidth of conventional feed system. Thus the suggested feed hem antenna is suitable to feed horn for miniaturization of HPM antenna system.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.413-420
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• 1986

This study was attemtped to improve the conventional processing method and to establish the basic data for evaluating the product suitabilities of dried loach. The semidressed raw material were salted in 15% NaCl solution for 15 minutes and dried to contain about 44% of water, and then heated about 10 minutes at $80^{\circ}C$ controlled by microwave (2,450 MHz). The moisture content of monolayer value for the product showed 5.34% and its water activity was 0.28. The optimum relative humidity for the storage was recognized to be from 32% to 44%. The average shelf life around the year of the Nylon-PVC-PE $(40\;{\mu})$ packed product in domestic circulation market was estimated as 207.4 days. In comparison with raw material, the contents of the major amino acids, glutamic acid, alanine and valine in the product were shown to be slightly increased, while the level of lysine, aspartic acid and methionine were slightly decreased. The contents of saturated fatty acids and oleic acid were shown to be slightly increased, while the other fatty acids tended to be slightly decreased.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.125-131
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• 1998

The change of pectinesterase (PE) activity and pectin substances in fig fruit were investigated and low sugar jams prepared by various methods from fig fruit were compared. Fig fruit PE, which began to show the activity at the harvest time, was not inactivated and had slight activity during frozen storage at $-25^{\circ}C$. The amount of alcohol insoluble solid (AIS) and the degree of esterification (DE) of AIS were reduced by its own PE activity. However the intrinsic PE of fig fruit was not enough to make low-methoxyl pectin below 50% of DE. Fig pulp treated by its own PE and combination of fig PE and orange PE could make low-methoxyl pectin. After PE treatments, fig pulp adjusted below pH 4.0 by addition of citric acid kept red colour. Fig Jams processed by various methods had lower soluble solid $(31{\sim}49^{\circ}Brix)$ compared with conventional fig jam. Five kinds of fig jams out of those showed higher score than others in the sensory evaluation. For preparation of the five jams, the fig pulps with or without 1% pectin were treated at $50^{\circ}C$ for 25 minutes with addition of orange PE (200 units/400 g pulp). The treated pulps were added with 0.25% citric acid, 0.7% calcium and 20% cane sugar. The mixed pulps were prepared for jams containing low sugar by hot plate or microwave or refrigeration (excepting the mixed pulp without pectin).

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.191-201
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• 2011

Soybean has widely grown for its edible bean which has numerous uses. Microwave remote sensing has a great potential over the conventional remote sensing with the visible and infrared spectra due to its all-weather day-and-night imaging capabilities. In this investigation, a ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the crop conditions of a soybean field. Polarimetric backscatter data at L, C, and X-bands were acquired every 10 minutes on the microwave observations at various soybean stages. The polarimetric scatterometer consists of a vector network analyzer, a microwave switch, radio frequency cables, power unit and a personal computer. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. The backscattering coefficients were calculated from the measured data at incidence angle $40^{\circ}$ and full polarization (HH, VV, HV, VH) by applying the radar equation. The soybean growth data such as leaf area index (LAI), plant height, fresh and dry weight, vegetation water content and pod weight were measured periodically throughout the growth season. We measured the temporal variations of backscattering coefficients of the soybean crop at L, C, and X-bands during a soybean growth period. In the three bands, VV-polarized backscattering coefficients were higher than HH-polarized backscattering coefficients until mid-June, and thereafter HH-polarized backscattering coefficients were higher than VV-, HV-polarized back scattering coefficients. However, the cross-over stage (HH > VV) was different for each frequency: DOY 200 for L-band and DOY 210 for both C and X-bands. The temporal trend of the backscattering coefficients for all bands agreed with the soybean growth data such as LAI, dry weight and plant height; i.e., increased until about DOY 271 and decreased afterward. We plotted the relationship between the backscattering coefficients with three bands and soybean growth parameters. The growth parameters were highly correlated with HH-polarization at L-band (over r=0.92).

• Preventive Nutrition and Food Science
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• v.10 no.1
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• pp.6-10
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• 2005

The trypsin inhibitor activity (TIA) of various soybean cultivars was evaluated by measuring the inhibition of trypsin activity using N-benzoyl-DL-arginine-p-nitro-anilide (BAPNA) as the substrate. The TIA values of eleven white shelled soybean cultivars including a glyphosate-tolerant soybean (16.58 to 17.90㎎/g) were not significantly different among cultivars. Black shelled soybeans had higher TIA values, ranging from 40.09 to 52.11㎎/g, compared to white shelled soybeans (p<0.05). When the TIA of commercially processed soybean foods were determined, no TIA was detected in soysauce, tofu and soybean paste. During conventional moist heating, the IT/sub 50/ (Time required to reach 50% inhibition of TIA) values were decreased as heating temperature and cooking pressure increased. The IT/sub 50/ values of moist heating were estimated to be 91.68, 37.71 and 19.50 min at 60, 80 and 100℃, respectively. The IT/sub 50/ value of microwave cooking was 4.75 min at medium heat, while that of the pressure cooking at 120℃ was only 2.62min. Moreover, there was a negative relationship between temperature and IT/sub 50/ values (R=0.92, p<0.01). The TIA of soybean sprouts was completely inactivated after heating at 100℃ for 5 min, although fresh soybean sprouts showed one fifth of the TIA value of white shelled soybeans. Based on our results, pressure cooking is the most effective cooking method to reduce TIA in soybeans.

• Mycobiology
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• v.40 no.1
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• pp.20-26
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• 2012

The complexes of tailor made ligands with life essential metal ions may be an emerging area to answer the problems of multi drug resistance. The coordination complexes of VO(II), Co(II), Ni(II) and Cu(II) with the Schiff bases derived from isatin with 3-chloro-4-floroaniline and 2-pyridinecarboxaldehyde with 4-aminoantipyrine have been synthesized by conventional as well as microwave methods. These compounds have been characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, FAB mass and magnetic susceptibility measurements. FAB mass data show degradation of complexes. Both the ligands behave as bidentate and tridentate coordinating through O and N donor. The complexes exhibit coordination number 4, 5 or 6. The Schiff base and metal complexes show a good activity against the bacteria; $Staphylococcus$ $aureus$, $Escherichia$ $coli$ and $Streptococcus$ $fecalis$ and fungi $Aspergillus$ $niger$, $Trichoderma$ $polysporum$, $Candida$ $albicans$ and $Aspergillus$ $flavus$. The antimicrobial results also indicate that the metal complexes are better antimicrobial agents as compared to the Schiff bases. The minimum inhibitory concentrations of the metal complexes were found in the range 10-40 ${\mu}g/mL$.

• Corrosion Science and Technology
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• v.12 no.2
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• pp.65-78
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• 2013

The present investigation deals with the corrosion inhibition of mild steel in 1M $H_2SO_4$ with 1, 4-dihydro pyridine and its derivatives prepared using microwave activation method. The synthesis of inhibitor was confirmed by IR spectra. The effect of 1, 4-dihydropyridine derivatives on the corrosion inhibition of mild steel in 1M $H_2SO_4$ was studied using weight loss and electrochemical polarization techniques. Influence of temperature (303-333K) and synergistic effect of halide ions ($I^-$, $Br^-$ and $Cl^-$) on the inhibition behaviour was also studied. Corrosion products on the metal surface were analyzed by scanning electron microscopy (SEM) and a possible mechanism of inhibition by the compounds is suggested. Thermodynamic parameters were calculated using weight loss data in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied compounds acted as mixed type inhibitor but slightly anodic in nature. Electrochemical impedance measurements revealed that the compounds were adsorbed onto the carbon steel surface and the adsorption obeyed the Langmuir adsorption isotherm. The synergistic effect of halide ions on the IE increases with increase in concentration. The IE obtained from atomic absorption spectrophotometric studies was found to be in good agreement with that obtained from the conventional weight loss method. SEM revealed the information of a smooth, dense protective layer in presence of the inhibitors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.449-456
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• 2018

Herein, several multibeam forming methods that can be applied to microwave wireless power transmission are presented. Because the conventional multibeam forming methods do not consider an active element pattern(AEP), an intended beam shape will contain a steering angle error when applied to an actual system. To solve this problem, a method of considering the average of the AEP and a method of considering all the AEPs by the modified Fourier series method have been proposed. We confirmed that the proposed method reduces the error with the intended beam shape in the multibeam formation. In addition, for the side lobe level(SLL) and null control, a method of multibeam forming by applying the superposition principle to the Dolph-Tschebyscheff method is proposed. We also confirmed that SLL control can be simultaneously achieved with the multibeam formation.