• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.4 s.107
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• pp.335-340
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• 2006

In this paper, a rectangular-cavity-type exposure system for in vitro experiments has been developed fur the biological effect studies of radio frequency fields from handhold wireless telephones. It ia fed with a ${\lambda}_g/8$ monopole antennas at the ${\lambda}_g/4$ position of the top plate in order to excite fundamental $TE_{102}$ mode and it allows the uniform exposure of one 8.5 cm(inner diameter) petri dish. SARs inside the exposed medium have been characterized by numerical simulations, using the FDTD method and by experimental dosimetry with fiberoptic temperature probes (model 790, Luxtron Corp.).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.137-148
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• 2014

In this paper, design of a UWB MIMO antenna for an on-body application is proposed and antenna performance with body effect and the impact on the human body are investigated. The proposed MIMO antenna is composed of UWB antenna above ground plane and an additional plunger shaped isolator located between the two monopole antennas to enhance the isolation characteristic. The simulation and measurement are performed to analyze the effect of the human body on antenna performance when the human body is located in the near field of the antenna. According to the measurement results, the measured SAR values for antennas 1 and 2 are 0.132 W/kg and 0.08 W/kg, respectively when 0.5 mW input power is delivered. These values satisfy the FCC guideline which ragulates that the 1-g average SAR should be lower than 1.6 W/kg.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.255-258
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• 2014

Imaging in bistatic radar has been known a more difficult task than that in monostatic radar. It is because the behavior of the bistatic range and the bistatic Doppler due to the motion of a transmitter and a receiver is so random that the compensation procedure, which we call an imaging algorithm, is quite complicated. This paper presents a bistatic radar imaging algorithm that can be used in some specific bistatic radar geometry. We show this geometry can present rectangular-like resolution cell on isorange-isoDoppler contours map. We also present the associated resolution and simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.349-356
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• 2015

In this paper, MIMO antenna with low correlation for LTE band 5(824~894 MHz) was designed by adopting monopole antenna and slot antenna. Based on ground characteristic mode theory, MIMO antenna was designed using different types of antennas for enhancement of correlation. MIMO antenna using PIFA and slot type antennas is proposed and correlation coefficient was compared with MIMO antenna using two PIFAs. Average correlation coefficient of MIMO antenna using two PIFAs was 0.71 but the proposed MIMO antenna had very low correlation coefficient of 0.17.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1086-1095
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• 2008

In this paper, we designed and fabricated the trapezoidal antenna using the CPWG structure for Wibro and WLAN communications. This antenna has broadband characteristics using the basic trapezoidal antenna, and an H-shaped parasitic patch is making an expansion of resonance bandwidth and bringing stability of impedance matching. Especially, CPWG structure is combined two kinds of the structure which of a monopole antenna and a coplanar waveguide antenna. They make up for the weak point of the CPW which is variation of impedance matching according to varying the gap or size of the feed line and the ground. The designed antenna has occurred resonances of which the band of 2.2 GHz to 4.6 GHz(70.5 %) below the return loss of -10 dB($VSWR{\leq}2$) obtained in measurement, and it has an omnidirectional radiation pattern of H-plane. In addition, the changes of impedance matching appear slightly caused by the effects of the ground plane and the feed line.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1053-1058
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• 2016

The eLoran(enhanced Long Range Navigation) transmitting antenna is analyzed for co-location with an AM transmitting antenna in an MF transmitting site. To compensate for the loading effect, the umbrella-type loading is applied for eLoran antenna. The validity of the co-location between the MF antenna and the eLoran antenna is verified through the simulation results of the radiation pattern and the return loss. Also, coupling including antenna matching circuit is analyzed to verify the effect of the transmitting circuit. The coupling between the LF and eLoran antenna is -53.3 dB at 100 kHz and -64.8 dB at 1,053 kHz, respectively.

• Journal of Korean Medicine Rehabilitation
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• v.15 no.2
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• pp.31-43
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• 2005

목적 : 방풍은 임상적으로 관절염을 포함한 다양한 염증성 질환 치료제로 사용되어 왔다. 본 연구에서는 인간 비만세포를 이용하여 세포 독성에 영향을 주지 않는 농도에서 방풍의 항염 효과 및 그 기전을 검토했다. 방법 : 인간의 HMC-1세포를 IMDM에서 페니실린, 스트렙토마이신, 모노티오글리세린을 첨가하여 배양하고 방품추출액을 투여하였다. 그 다음 MTT, CLISA, RT-PCR, 세포내 칼슘측정, 핵단백분석을 이용하여 TNF-${\alpha}$, IL-6, IL-8 각각의 형성과 mRNA발현, 세포내 칼슘 수준, NF-${\kappa}B$ 발현에 대한 방풍추출액의 반응을 측정하고 통계처리 하였다. 결과 : 방풍은 PMA와 calcium ionophore A23187로 활성화된 비민세포에서 세포내 칼슘 수준과 NF-${\kappa}B$, TNF-${\alpha}$와 IL-6의 발현을 억제시켰고 RT-PCR을 이용한 mRNA 발현에서 TNF-${\alpha}$와 IL-6의 발현을 억제하였다. 결론 : 방풍은 비만세포내 칼슘 수준 및 NF-${\kappa}B$의 활성을 억제하고 염증성 세포 활성 물질인 TNF-${\alpha}$와 IL-6의 분비도 억제하여 항염효과를 나타냄을 암시하고 있다.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.27-31
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• 2012

This study was designed to examine the feasibility of functionalized mesoporous silica as the adsorbent for benzene, toluene, ethylbenzene, and xylene isomers (BTEX) in groundwater. p-Xylene was used as the model compound of BTEX. A series of functionalized mesoporous silica with MCM-41 type of structure was synthesized using a co-condensation method. Monoamine, triamine, nitrile, phenyl, and octyl groups were functionalized to the mesoporous silica structure. Adsorption sites for p-Xylene in a functionalized mesoporous silica were Si-O-Si covalent bond, the surfactant, and the functional group. Octyl-functionalized mesoporous silica with stearyltrimethylammonium chloride as a surfactant showed the highest adsorption ability. The maximum xylene adsorption capacity of the octyl-functionalized mesoporous silica with stearyltrimethylammonium chloride based on Langmuir model was 4.17 mmol/g on $20^{\circ}C$, which was 2.9 times higher than that of MCM-41.

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.5-12
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• 2005

In order to investigate the strength and deformation anisotropy of compacted decomposed granite soils, a series of unsaturated-drained triaxial compression tests were performed. The sample used in the study was decomposed granite soil from Shimonoseki in Yamaguchi prefecture. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane), 0, 45 and 90 degrees. The compression strain of specimens subjected to isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clear with low confining stress. Moreover, it was recognized that although the sedimentation angle and preparation methods were different, the dilatancy rate was relative to the increment of strength due to dilatancy. Therefore, it may be concluded that the compacted specimen has anisotropic mechanical properties similar to those of sand with initial fabric anisotropy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3C
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• pp.224-231
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• 2003

In this paper we proposed system parameter values of ultra-wideband Impulse Radio systems for the frequency band(3.1~10.6GHz), which is allocated by Federal Communications Commission(FCC). We also analyzed performance of the proposed system in the multiple access interference environment. According to result, application of possible pulse duration($t_{n}$) is very limited by 0.04~0.0326 ns in permission frequency range that establish in FCC. In the case of the same pulse signal power, we could know that system performance was changed by pulse repetition number($N_{s}$ ) regardless of pulse duration. Thus, We could know that we have to need duration of monocycle pulse and setting of frame un it time(Τ$_{f}$ ) according to multi user numbers and design proper pulse repetition number by transfer rate in multiple access systems design. In the IR system that needs high speed transmission more than 50 Mbps in multiple access interference environment, we could know that very serious performance decrease by multiple access interference happens. Therefore, as the design of high speed multiple access IR system, it should be designed to additional improvement techniques that can remove multiple access interference at the same time.