• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.31-38
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• 2020

In this paper, we propose a quadruple band antenna for GPS/WLAN/WiMAX application. The proposed antenna has quadruple band characteristics by considering the interconnection of four strip lines and DGS on the ground place. The total substrate size is 20.0 mm (W1) ⨯27.0 mm (L1), thickness (h) 1.0 mm, and the dielectric constant is 4.4, which is made of 20.0 mm (W2)⨯ 27.0 mm (L8 + L6+ L10) antenna size on the FR-4 substrate. From the fabrication and measurement results, bandwidths of 60 MHz (1.525 to 1.585 GHz) bandwidth for GPS band, 825 MHz (3.31 to 4.135 GHz) bandwidth for WiMAX band and 480 MHz (2.395 to 2.975 GHz) and 385 MHz (5.10 to 5.485 GHz) bandwidth for WLAN band were obtained on the basis of -10 dB. Also, gain and radiation pattern characteristics are measured and shown in the frequency of triple band as required.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1189-1196
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• 2015

In this paper, a microstrip-fed multiband monopole antenna for GPS(Global positioning system)/WiMAX(:Worldwide interoperability for microwave access)/WLAN(Wireless Local Area Networks) for applications was designed, fabricated and measured. The proposed antenna is based on a microstrip-fed structure, and composed of two rectangular double rings and L strips pair and then designed in order to get triple band characteristics. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS). The proposed antenna is made of $27.0{\times}54.0{\times}1.0mm3$ and is fabricated on the permittivity 4.4 FR-4 substrate. The experiment results shown that the proposed antenna obtained the -10 dB impedance bandwidth 300 MHz (1.325~1.625 GHz), 400 MHz (2.275~2.675 GHz), and 600 MHz (3.15~3.75 GHz) covering the GPS/WiMAX/WLAN bands. Also, the proposed antenna measured gain and radiation patterns characteristics for required operating bands.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.48-61
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• 2007

WiBro (Wireless Broadband) service, developed in Korea, can provide the host mobility while its users hang around within the subnet. Next-generation Internet protocols, IPv6 and Mobile IPv6 (MIPv6), provide a plenty of addresses to the nodes and enable the handover between different subnets. However, MIPv6 is not enough to support a real time service such as VoIP (Voice over IP) due to the long latency, and it is necessary to develop an enhanced handover mechanism which is optimized to the WiBro networks. In this paper, we suggest an improved fast handover mechanism while the mobile node moves around WiBro networks. The proposal is based on Fast Mobile IPv6 (FMIPv6) which is the representative protocol for fast handover, and reduces the handover latency by the close interaction between the link layer (WiBro MAC) and IP layer (FMIPv6). Finally, we analyze the performance of proposed mechanism through the mathematical analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.387-393
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• 2007

In this paper, we propose the load control procedure for WiBro system in order to keep the data traffic throughput maximum. The transmitter at a mobile terminal can estimate maximum available power for each user and then the maximum number of subchannels can be calculated considering the total available power. The data traffic throughput and the total throughput (the sum of signaling traffic and data traffic throughput) are considered. As the number of bandwidth requests per frame increases, the data traffic throughput can significantly decrease. Therefore, the load control procedure is indispensible to maintain the data throughput at the maximum level. So, we propose the load control procedure to prevent data traffic throughput from decreasing and evaluate the proposed procedure through the computer simulation under the multi-user environment. The maximum throughput can be maintained by applying the proposed procedure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.552-559
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• 2011

In this paper, the frequency reconfigurable antenna is proposed and designed. The proposed antenna is designed using the vertically stacked dipole structures and have the operating band for Cellular, PCS/WCDMA/Wibro/WiFi and WiMAX. The operating frequency band is selected by three pair of PIN diodes using the voltage difference between each dipole antenna and feeding transmission lines. The proposed antenna meets the required operating bandwidth and the maximum gain for each frequency band are measured as 6.3 dBi, 5.4 dBi and 5.8 dBi, respectively. The proposed antenna in this paper can be applied for the future mobile small base station or repeater antenna because this antenna can provide the small size and high gain features.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.15-22
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• 2018

In this paper, a microstrip-fed triple-band monopole antenna for WLAN/WiMAX applications was proposed. The proposed antenna is consist of two arc-shaped and one strip line structure, then get the three current path and then designed in order to get triple resonant characteristics. We carried out simulation about parameters. Taking account of coupling effect, Adjusted the length of the two arc-shaped and one strip line, we get the optimized parameters. The proposed antenna is fabricated on an FR-4 substrate, the dielectric constant is 4.4, and total size is $23.5mm(W1){\times}32.0mm(L1){\times}1.0mm(t)$, and its proposed antenna size is $21.0mm(W6){\times}31.0mm(L7)$. From the measured results, return loss of the proposed antenna satisfied return loss 927 MHz (1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), and 1,415 MHz (5.13~6.545 GHz). And measured results of gain and radiation patterns displayed for operating bands.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.162-169
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• 2009

Message Authentication Code (MAC) assures integrity of messages. In Mobile WiMAX, 128-bit Cipher-based MAC (CMAC) is calculated for management messages but only the least significant half is actually used truncating the most significant 64 bits. Naming these unused most significant 64bits Shared Authentication Information (SAI), we suggest that SAI can be applied to protect the network from DDoS attack which exploits idle mode vulnerabilities. Since SAI is the unused half of CMAC, it is as secure as 64bits of CMAC and no additional calculations are needed to obtain it. Moreover, SAI doesn't have to be exchanged through air interface and shared only among MS, BS, and ASN Gateway. With these good properties, SAI can efficiently reduce the overheads of BS and ASN GW under the DDoS attack.

• Journal of Environmental Science International
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• v.27 no.4
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• pp.275-279
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• 2018

Water status of intact plants has been optically estimated by measuring reflectance at the wavelengths 1,450 nm and 1,900 nm based on their signal strengths. Although another water band at 970 nm is considered to have very small signals, the band apparently lies within the detection range of inexpensive spectrometer and plain charge-coupled device (CCD) camera used in wild fire studies. However measurement of the reflectance at 970 nm has been rarely applied to estimate the water status of dead plant materials such as fallen branch, twig, and leaf. To test the possibility of applying water reflectance at 970 nm to estimate the water content (WC) in leaf litter, the reflectance in various WC values were measured in the leaf litter of three Quercus species (Q aliena, Q aliena, Q mongolica, and Quercus variabilis). The results showed that the WC in the leaf litter can be determined by reflectance water index (WI) in the three Quercus species ($WC=1,450{\times}WI-1,378.8$, r=0.865). However, there was no interaction effect in the relationship between WI and WC among the litter of the three Quercus species.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.59-67
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• 2013

Compared to the conventional Hardware-oriented base stations, Software Defined Radio (SDR)-based base station provides various advantages especially in flexibility and expandability. It enables the multimode capability required in 4th-generation (4G) environment which aims at a convergence network of various kinds of communication standards. However, since a single base station processes all data required in various multiple waveforms, the SDR base station faces a problem of data processing speed. In this paper, we propose a new concept of SDR base station system which adopts a parallel processing technology of clustering environment. We implemented a WiMAX system with SDR concept which adopts the Message Passing Interface (MPI) technology which enables the speed-up operations. In order to maximize the efficiency of parallel processing in signal processing, we analyze how the algorithm at each of modules is related to data to be processed. Through the implemented system, we show a drastic improvement in operation time due to parallel processing using the proposed MPI technology. In addition, we demonstrate a feasibility of SDR system for 4G or even beyond-4G as well.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.306-313
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• 2024

Given the diversity of vegetables utilized in food fermentation and various lactic acid bacteria (LAB) populations in these materials, comprehensive studies on LAB from vegetable foods, including kimchi, are imperative. Therefore, this study aimed to investigate the obesity-related inflammation response of three metabolites-phenyllactic acid (PLA), indole-3-lactic acid (ILA), and leucic acid (LA)-produced by LAB (Companilactobacillus allii WiKim39 and Lactococcus lactis WiKim0124) isolated from kimchi. Their effects on tumor necrosis factor-α-induced changes in adipokines and inflammatory response in adipose-derived human mesenchymal stem cells were examined. The study results showed that PLA, ILA, and LA, particularly PLA, effectively reduced lipid accumulation and triglyceride, glycerol, free fatty acid, and adiponectin levels. Furthermore, the identified metabolites were found to modulate the expression of signaling proteins involved in adipogenesis and inflammation. Specifically, these metabolites were associated with enriched expression in the chemokine signaling pathway and cytokine-cytokine receptor interaction, which are critical pathways involved in regulating immune responses and inflammation. PLA, ILA, and LA also suppressed the secretion of pro-inflammatory cytokines and several inflammatory markers, with the PLA-treated group exhibiting the lowest levels. These results suggest that PLA, ILA, and LA are potential therapeutic agents for treating obesity and inflammation by regulating adipokine secretion and suppressing pro-inflammatory cytokine production.