• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2051-2056
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• 2009

The rate constants of alkaline fading of malachite green ($MG^+$) was measured in the presence of nonionic (TX-100), cationic (DTAB) and anionic (SDS) surfactants. This reaction was studied under pseudo-first-order conditions at 283∼303 K. The rate of fading reaction showed noticeable dependence on the electrical charge of the used surfactants. It was observed that the reaction rate constants were increased in the presence of TX-100 and DTAB and decreased in the presence of SDS. According to Hughs-Ingold rules for nucleophilic substitution reactions, the electric charge of MG/surfactant compound along with decrease in dielectric constant of $MG^+$ micro-environment in this compound varies the rate of fading reaction. Binding constants of surfactant molecules to $MG^+$ were calculated using cooperativity, pseudo-phase ion exchange and classical models and the related thermodynamic parameters were obtained by classical model. The results show that the binding of $MG^+$ to TX-100 is exothermic and binding of $MG^+$ to DTAB and SDS in some concentration ranges of the used surfactants is endothermic and in the other ones is exothermic.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1227-1232
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• 2011

Using the notch and isolation, we investigated the insertion loss and isolation characterics of the fabricated dielectric duplexers and bandpass filters for CDMA and W-CDMA dualband. Insertion loss(Tx band) and isolation(between Tx and Rx) of duplxer were about -2.1708dB and 45dB at CDMA band, respectively. Also, in the case of W-CDMA, the insertion loss(Tx band) and isolation(between Tx and Rx) showed about -2.6946 and 100dB, respectively. Summering the aboved results, fabricated the dielectric duplexers and bandpass filters will be contributed the increase of atttenuation and the decrease of interference at CDMA and W-CDMA dualband.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.726-736
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• 2004

In this paper, kinetics of reaction between Bromophenol blue (BPB) and $OH^-$, called fading, has been studied through a spectrophotometric method in the presence of nonionic Triton X-100 (TX-100), anionic sodium dodecyl sulfate (SDS) and cationic dodecyl trimethylammonium bromide (DTAB) surfactants. The influence of changes in the surfactant concentration on the observed rate constant was investigated. The results are treated quantitatively by pseudophase ion-exchange (PPIE) model and a new simple model called "classical model". The binding constants of BPB molecules to the micelles and free molecules of surfactants, their stoichiometric ratios and thermodynamic parameters of binding have been evaluated. It was found that SDS has nearly no effect on the fading rate up to 10 mM, whereas TX-100 and DTAB interact with BPB which reduce the reaction rate. By the use of fading reaction of BPB, the binding constants of SDS molecules to TX-100 micelles and their Langmuir and Freundlich adsorption isotherms were obtained and when mixtures of DTAB and TX-100 were used, no interaction was observed between these two surfactants.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.784-789
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• 2011

In this paper, a tunable integrated transmitter leakage canceller based on an autotransformer for ultra-high-frequency (UHF) RFID readers is presented. The proposed TX leakage canceller consists of an autotransformer, a digital tuning capacitor, a voltage controlled tuning resistor, and a compensating amplifier, and it is designed using 0.13 ${\mu}m$ 1-poly 6-metal RF CMOS process. The simulation results show that the proposed structure has over 55 dB rejection characteristic between a transmitter and a receiver and a 2.5 dB of the RX insertion loss. The TX leakage canceller can be digitally tuned from 825 MHz to 985 MHz with the tuning capacitor and it can be fully integrated.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.4 s.23
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• pp.120-129
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• 2005

To analyze a blast effect of developed explosives, three different kinds of aluminized tastable explosives and melted cast explosive TNT were used. Conventional explosive TNT was used as a reference. Each tested explosive charge of 340mm diameter spherical type was initiated at the charge center with DXD-65(${\sim}750g$) booster and RP-87 EBW detonator. Thirteen piezo type pressure sensors were located at a range from 4 to 50m away from the charge. From the blast wave profiles, we calculated a peak blast pressure and impulse of the explosion. The calculated pressures and in pulses were converted to TNT Equivalent Weight(TEW) factor by the scaling ]aw method. The average TEW factors based on the blast pressure of TX-01, TX-02, TX-03, TX-04 were 1.298, 1.05, 1.266, 1.274 and the average TEW factors based on impulse were 1.504, 1.686, 1.640, 1.679. From the results, we concluded that TEW factors based on blast pressure and based on impulse of aluminized explosives were superior to TNT. This results are owing to the high contents of aluminum in formulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.101-104
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• 2005

본 논문에서는 국내에서 채택한 ATSC-DTV (Advanced Television System Committee-Digital Television)의 단일주파 수망 (SFN; Single Frequency Network) 구성을 위한 TxID (Transmitter Identification)용 ZCD (Zero Correlation Duration)확산코드 기반의 부분상관 정합필터를 새롭게 제안하였다. 본 논문에서 제안한 정합필터의 구현 알고리즘은 TxID에 있어서 기존의 정합필터 구조를 적용할 경우에 발생되는 소비전력 문제나 하드웨어 구현의 어려움을 획기적으로 해결할 수 있다는 잇점을 갖는다. 따라서 본 논문에서는 이러한 다양한 잇점을 갖는 새롭게 제안한 ZCD용 부분상관 정합필터를 FPGA (Field Programmable Gate Array)를 이용한 디지털 하드웨어로 구현하고 그 성능을 분석함으로써 유용성을 확인하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.574-581
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• 2002

Microstrip $8{ imes}2$ sub-array antennas for a extension to active phased array antennas are designed, fabricated and measured for TX/RX dual operation in satellite communication and a reception of satellite broadcasting. For the frequency range from 11.7 to 12.75 GHz for RX and from 14 to 14.5 GHz for TX, two orthogonal linear polarizations of ${pm}45^{\circ}$ are used to transmit and receive simultaneously with one radiator. They adopt dual resonance between two patches for wideband characteristics in RX band and show isolation characteristics over 20 dB. An electrical beam tilt of $30^{\circ}$ is achieved and a tapered power distribution, narrow element spacing are used for the purpose of low side-lobe characteristics.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.43-44
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• 2015

LTE-Advanced system has been deployed with 2 and 4 transmission antennas (Tx) while the specification supports up to 8Tx. Due to deployment space, antenna dimension and complexity, the needs of deploying 8Tx system has not been motivated by operators. Recently, three dimensional (3D) beamforming with active antenna has attracted significant attention in the wireless industry. By incorporating 2D active array into LTE-A systems, the system offers freedom in controlling radiation on elevation and horizontal dimension. When the number of antennas increases in the form of 2D arrangement, spatial separation can be realized simultaneously in horizontal and elevation domain and vertical beam-steering can increase SINR of UEs in high floors. In this paper, we study the system operations and implementations for supporting 3D beamforming with 8Tx antennas. In our schemes, by reusing the conventional CSI feedback framework, the system can operate 2D active array without harming the backward compatibility. Evaluation results show that 3D beamforming provides capacity boosting over the conventional 2D beamforming systems while keeping same antenna structure.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.236-241
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• 2019

This paper will read about a multichannel frequency-modulated continuous wave (FMCW) radar sensor with switching transmit (TX) antennas is developed at W-band. To achieve a high angular resolution, a uniform linear array consisting of 5 switching-TX and 12 receive (RX) antennas is employed with the digital beamforming technique. The overall radar front-end module comprises a W-band transceiver and TX/RX antennas. A multichannel transceiver module consists of 5 up-conversion and 12 down-conversion channels, where one of the TX channels is sequentially switched ON. For developing transmitter, we developed an HPA (high power amplified) MMIC chip for W-band radar system and fabricated a transmitter module using this chip. In order to develop the W-band transmitter, we analyzed the important antenna transition structure from HPA MMIC line to W/G (Waveguide)antenna via M/S(microstrip) and fabricated it with 5 transmission channels. As a result, the output power of the transmitter was within 1 dB of the error range after analysis and measurement under normal temperature and environmental conditions.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.135-142
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• 2007

We used the Braun-Blanquet method to study coastal dune vegetation of South Korea. Coastal vegetation was monitored in thirty sites from April 2004 to September 2005. Seventeen plant communities were classified into five groups as follows: A. Two associations of herbaceous sand dune plants in Salsoletea komarovii Ohba, Miyawaki et Tx. 1973 (Calystegia soldanella community, Lathyrus japonicus-Calystegia soldanella community), B. Twelve associations of herbaceous perennial sand dune plants in Glehnietea littoralis Ohba, Miyawaki et Tx. 1973 (Carex pumila community, Elymus mollis community, Vitex rotundifolia-Elymus mollis community, Ixeris repens community, Elymus mollis-Ixeris repens community, Lathyrus japonicus community, Messershmidia sibirica community, Glehnia littoralis community, Carex kobomugi community, Calystegia solda-nella-Carex kobomugi community, Ishaemum anthephoroides community, Zoysia macrostachya community), C. One association of shrubby perennial sand dune plant in Viticetea rotundifoliae Ohba, Miyawaki et Tx. 1973 (Vitex rotundifolia community), D. One association of shrubby perennial sand dune plant in Rosetea multiflorae Ohba, Miyawaki et Tx. 1973 (Rosa rugosa community), E. The naturalized community (Diodia teres community).