• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.475-483
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• 2013

In this paper, a coupled-fed monopole antenna for LTE/WWAN mobile handset applications is presented. The antenna consists of a monopole, a coupling strip, a feeding pad, a stub, and a shorting strip. The basic resonance of the monopole combines with the resonance formed by the coupling that occurs between the coupling strip and the feeding pad to include LTE700(698~787 MHz), GSM850(824~894 MHz), and GSM900(890~960 MHz) bands. The resonance of the stub combines with the harmonics of the monopole to include GSM1800(1,710~1,880 MHz), GSM1900(1,850~1,990 MHz), and UMTS(1,920~2,170 MHz) bands. Therefore, the proposed antenna is suitable as antenna for hexa-band mobile handset applications, covering LTE700, GSM850, GSM900, GSM1800, GSM1900, and UMTS bands. A stable and omni-directional radiation pattern with reasonable gains is observed within the operating bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.3
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• pp.237-245
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• 2017

In this paper, a monopulse sensor which determines a target location using amplitude-comparison monopulse technique is presented. This sensor can allow the missile to track the target when additional jamming signals are not presented. Then, we applied the spot noise jamming technique to the monopulse sensor. Based on the simulation results, we can effectively figure out the performances of the spot noise jamming technique for the monopulse sensor in various jamming scenarios.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.4
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• pp.245-253
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• 2020

In this study, natural frequencies are compared using several pile-soil interaction (PSI) models to evaluate the effects of each model on resonance safety checks for a monopile type of wind turbine structure. Base spring, distributed spring, and three-dimensional brick-shell models represented the PSIs in the finite element model. To analyze the effects of the PSI models on a natural frequency, after a stiffness matrix calculation and Winkler-based beam model for base spring and distributed spring models were presented, respectively; natural frequencies from these models were investigated for monopiles with different geometries and soil properties. These results were compared with those from the brick-shell model. The results show that differences in the first natural frequency of the monopiles from each model are small when the small diameter of monopile penetrates hard soil and rock, while the distributed spring model can over-estimate the natural frequency for large monopiles installed in weak soil. Thus, an appropriate PSI model for natural frequency analyses should be adopted by considering soil conditions and structure scale.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.87-94
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• 2008

This paper proposes a high-gain monopulse antenna using the folded reflectarray for a monopulse target-tracking radar systems designed at the center frequency of 94 GHz. In target-tracking radar systems, the angle of arrival of the incoming wave Is determined by comparing the signal received on two or more non-coincident antenna patterns. This is the physical basis of most target-tracking techniques and the comparison is made simultaneously in a monopulse radar systems. In this paper, the antenna consists of polarizing grid, reflectarray, multimode feed horn, and comparator implemented by wavguide. The antenna is able to have three radiation patterns by using the monopulse feed systems assembled by multimode feed horn and comparator. The antenna demonstrates maximum gains 36dB, 33.5dB and 27.2dB at sum mode, azimuth mode, and evevation mode respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.7
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• pp.666-674
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• 2015

In this paper, we introduce an adaptive phase-comparison monopulse technique for angle estimation of two targets in the same antenna beam. The proposed method determines a more suitable technique(between conventional phase comparison monopulse technique and Zheng's method) based on interference between two targets in Fourier domain. Consequently, regardless of the interference, angles of each individual target can be accurately estimated by means of the proposed method. In simulations, we assumed that two point targets with same velocity are located in the same antenna beam, and the accuracy improvement of the proposed method is verified by using several simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1225-1232
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• 2009

In this paper, a parabolic edge planar monopole antenna for indoor DTV reception is presented. The antenna has broadband property with the planar monopole and ground of parabolic edges. It is designed close to self-complementary structure as changing curvature of edges of monopole and ground. Monopole and ground conductors of the antenna are on the same plane, and excited through CPW feeding. It is fabricated on an FR4 dielectric substrate of $\varepsilon_r=4.4$, and the dimension is $40\;mm{\times}200\;mm{\times}1.6\;mm$. Return loss is larger than 10 dB in 470~806 MHz. Maximum gain is 1.86 dBi on E-plane at 810 MHz and 3.86 dBi on H-plane at 600 MHz.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.154-161
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• 1993

Four kinds of new phosphinate derivatives with a pendant monoazacrown ether were synthesized and their biological activities were tested. These biologically active phosphinates were synthesized in relatively good yields (61∼72%) by one step reactions of phenylphosphinate with aldehyde and monoazacrown ether. Toxicity of these compounds was tested by intraperitoneal injection of the compounds to male mouse and revealed $LD_{50}$ value of 65∼90 mg/kg, which showed enhanced toxicity by attachment of a pendant azacrown ether to a simple phenylphosphinate structure. Although the ring size effect of the pendant crown ethers, (monoaza-15-crown-5 and monoazo-18-crown-6), beening negligible, the identity of the ester functional group in the phosphinate structure exerted sizable influence on toxicity. Thus, phosphinate derivative with octyl or propyl ester group showed somewhat higher toxicity than that with ethyl ester group.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.2
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• pp.146-149
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• 2018

A monopulse sensor is used to estimate the angle of a target with respect to each received single pulse. It is well known that the cross-eye technique can result in an angle deception effect against monopulse sensors. To verify this effect, we propose a test environment configuration for the angle deception using monopulse receiving antennae and cross-eye transmitters in an anechoic chamber. Using the proposed test environment configuration, we have measured powers of the sum and difference of the signals received by the monopulse receiving antennae when the distance of the two cross-eye transmitters is varied. Finally, the angle deception performance related to the powers of the sum and difference signals was analyzed.

• Applied Biological Chemistry
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• v.40 no.5
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• pp.409-415
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• 1997

In order to find out the relationship between contained water and coloring rate of thiamine monosalts in preparations, three kinds of thiamine monorhodanate, -monoiodide, -monobromide were manufactured and investigated as powders, granules and compressed tablets, respectively. Apparent coloring rate constants and solubility in accordance with temperature changes were measured. Nature of contained water and coloration of thiamine monosalts in preparations was examined in detail. It was thereby found that if water attached in a free state, coloration occured whose degree was approximately proportional to the quantity of such water, and a linear relation was found to hold between the logarithm of the apparent coloring rate constants and the reciprocal of the absolute temperature in granules and compressed tablets.