• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.109-113
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• 2001

Presently, an inductor adapted at MMIC (Monolithic Microwave Integrated Circuit) which is used for cellular phone or PHS operates at quasi-microwave range over 800 MHz. However, a W-CDMA (Wideband Code Division Multiple Access) will use about 2 GHz range. Therefore magnetic film device should be compatible up to 2 GHz. We have deposited Co-Pd-Al-O system film using rf sputtering method which is expected up to 2 GHz, and investigated the effect of Pd content and magnetic field annealing. When Pd composition is 19%, Hk was 118 Oe, and ${\mu}$′showed flat frequency characteristics up to 1.5 GHz. The Q factor (=${\mu}$′/${\mu}$") was 23.3 at 1 GHz, 6.7 at 1.5 GHz and 1.5 at 2 GHz, respectively. Resonance frequency was 2 GHz. Therefore Co-Pd-Al-O thin film could be used at over 1 GHz, and also expected as an inductor material for wide band CDMA type cellular phone.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.737-747
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• 1997

performance of the cellular CDMA overlay system is analyzed which shares the same band with existing microwave narrowband system to enhance the spectral efficiency. To suppress the interfreence from narrowband system, we used a linear predicition filter that adopts the adaptive least mean square algorithm. Alalyzing the performance in the Personal Communication Services channel, characterized as a multipath Rician fadng channels, we considered the power control to solve the near-far problem, and-off and multipath diversity. We also considered interleaving and channel coding to improve BER performance of the CDMA system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.689-695
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• 2007

Wireline relay stations(RS's) are connected to cellular base stations(BS's) via radio-over-fiber(RoF) to enhance system capacity and to reduce shadow areas. Unlike wireless multi-hop systems, BS-to-RS signaling is transmitted out-of-band, thus reducing the effect of interference caused by frequency reuse. In this paper, antenna arrays used in addition to the wireline RS's are considered to evaluate the transmission capacity gain and performance variations according to the may structures. In particular, RS locations to maximize the gain, may distribution patterns for a given number of antenna elements, performance enhancement for a varying number of elements are experimentally determined to suggest a proper utilization of antenna ways in conjunction with wireline RS's.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1150-1156
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• 2007

In this paper, two novel subsurface antennas for remote management of underground facilities using PCS and cellular wireless network are proposed. The proposed subsurface antenna is a dual band circular patch which is inserted and molded for the protection of the antenna into a metal such as a manhole cover. The antenna is designed considering the resonant frequency shift of the antenna due to the insertion and molding. The measured return loss and receiving power of the fabricated antenna comparison with a dipole shows that two proposed subsurface antenna can be used for remote management of underground facilities using PCS and cellular systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.4 s.346
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• pp.52-57
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• 2006

In this paper, the triple-band planar monopole antennas are designed for cellular communication, WiBro and WLAN(IEEE802.11b/g) communication and WLAN(IEEE802.11a) communication of 5GHz band to using filled mobile convergence subscriber unit. Various types of antennas are designed and examined experimentally as bended in the low and middle band radiation elements to decrease antennas size and increased the width of radiation elements to improve bandwidth The proposed antennas are reduced by 11% in antenna size with bended low-band radiation elements down and are extended by $30%{\sim}40%$ in bandwidth by increasing the width of the radiation element at 800MHz band.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.335-340
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• 2005

In this paper, the triple-band planar monopole antennas are designed for cellular communication, WiBro and WLAN(IEEE802.llb/g) communication and WLAN(IEEE802.lla) communication of 5GHz band. Various types of antennas are designed and examined experimentally as bended in the low and middle band radiation elements to decrease antennas size and increased radiation elements width to improve bandwidth. The proposed antennas are improved by 11% in antenna size with bended low-band radiation elements down and are extended by 30%$\sim$40% in bandwidth by increasing the width of the radiation element at 800MHz band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.374-380
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• 2015

With explosion of wireless traffic it is required to further investigate the technologies on acquiring available spectrum resources and on sharing frequency with existing users. In 3GPP, it is started to study on feasibility and functional requirement of LTE standard in order to extend cellular services offered on only licensed band to 5 GHz unlicensed band. Operating scenario on LTE in unlicensed band is focused on carrier aggregation with licensed band, and the coexistence with Wi-Fi services in 5 GHz band is concerned as a major requirement. For a single global solution framework for licensed assisted access to unlicensed spectrum, listen-before-talk(LBT) mechanism of European regulation for fair access to channel under the coexistence environments is currently examined in 3GPP. In this paper, we evaluate two types of LBT, frame based equipment and load based equipment, with considering LTE carrier aggregation feature and performances of file transferred time and throughput.

• Molecules and Cells
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• v.20 no.1
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• pp.30-34
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• 2005

This study was carried out to identify a high-resolution marker for a gene conferring resistance to brown planthopper (BPH) biotype 1, using japonica type resistant lines. Bulked segregant analyses were conducted using 520 RAPD primers to identify RAPD fragments linked to the BPH resistance gene. Eleven RAPDs were shown to be polymorphic amplicons between resistant and susceptible progeny. One of these primers, OPE 18, which amplified a 923 bp band tightly linked to resistance, was converted into a sequence-tagged-site (STS) marker. The STS marker, BpE18-3, was easily detectable as a dominant band with tight linkage (3.9cM) to Bph1. It promises to be useful as a marker for assisted selection of resistant progeny in backcross breeding programs to introgress the resistance gene into elite japonica cultivars.

• Journal of electromagnetic engineering and science
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• v.1 no.1
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• pp.83-87
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• 2001

Many communication systems require bandpass filters with sharp skirt frequency characteristics in order to avoid the interferencce, which results in more order in the filter design. However, because of the limited Q values bandpass filters made of small sized ceramic resonators suffer from relatively large ripples at the band edges as the order of the filter increases. In order to compensate the large ripples while maintaining the sharp skirt frequency we propose a new RF amplitude equalizer. The equalizer made of two pole bandpass filter and an amplifier whose amplitude characteristics are the reverse of those of the bandapss filter. At the cellular band 9-pole bandpass filter with 10 MHz bandwidth exhibits 3 dB ripple when 8mm*8mm ceramic coaxial resonators are used. We added the RF equalizer to this filter and the flatness is improved as less than 1 dB.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.184-184
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• 2008

In this paper, a power divider with a multi-band and broadband are designed and fabricated using an InGaP/GaAs process. The design of this divider is based on multi-band because it is important in the next generation IMT-Advances system. In this design, power divider is fabricated with the frequency of 824 MHz to 894 MHz, 1.8 GHz to 2.2 GHz and 2.3 GHz to 2.4 GH for cellular, personal communication system (PCS) and Wireless Broadband Internet (WiBro). The topology of the designed power divider is based on the multi-section and fabricated using integrated passive device (IPD) library of nanoENS Inc. It is measured using network analyzer.