• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.283-284
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• 2008

A cross-layer optimization is becoming a popular design methodology for the IP based next generation wireless network. We begin by investigating a cross-layer optimization scheme to enhance the system performance in wireless networks. By applying cross-layer optimization methodology to WiBro distributed network, the WiBro systems are expected to gain significant performance improvement and resource utilization enhanced. For further study we highlight some open challenges and new opportunities for cross-layer design.

• Annual Conference of KIPS
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• 2010.04a
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• pp.637-640
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• 2010

VoIP 패킷을 전송하는데 있어서 MAC Header는 패킷의 데이터 크기에 비해 많은 대역폭을 할당 받고 있기에 제한된 무선자원의 사용에 부담이 되고 있다. 이러한 문제를 해결하기 위해 패킷 압축기법이나 패킷번들링을 이용하여 부하를 줄이기 위한 연구가 진행되고 있으며, 효율적인 무선 자원 이용의 향상을 가져올 수 있다. 따라서 본 연구에서는 WiMAX 시스템에서 스케줄링 서비스에 따른 VoIP서비스에서의 성능 분석을 하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.5
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• pp.73-78
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• 2009

We researched economic efficiency and possibility of game portal service based PDA/Smart phone by popularize of next generation portable internet WiBro. PDA/Smart phone are difficult to equal level content service with PC, because of it has low CPU and memory than PC. This paper are implemented paper of integrated server of Cable or Wireless for WiBro contents. In this research, we implemented and show test result of CP killer contents in PDA. It can apply to WiBro portable internet and has required many functions in integrated server for cable or wireless. CP Killer contents for WiBro portable internet is developed by PC server base on Window XP. It can accept next generation wireless LAN, portable internet and ubiquitous issues. We expect activation of commercial use that WiBro contents and server trading.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2345-2351
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• 2013

LBS(Location Based System) usually uses GPS technology to measure the exact position of the moving object. However, the method of managing location which utilizes the WiFi technology of mobile phone has not been introduced so far. The method of managing moving objects in view of the location of guardian has also not been proposed. In this paper, a new location management system of moving objects which take guardian's location into consideration is proposed. Specifically, the three methods of searching for missing child proposed in this paper are as follows : 1) a method based on an app for smart phone, 2) a method based on control server, 3) a method based on control server and fixed APs. Because the proposed system reflects the location of the guardian, the guardian is able to identify the state of child immediately and the workload can be reduced.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.338-346
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• 2018

In this paper, a monopole antenna applicable to WLAN/WiMAX system is designed and fabricated. The proposed antenna is designed to have three lines and one slit based on microstrip feeding to have triple band characteristics. We optimized the lengths and slits of the three lines to obtain the required characteristics for this paper. The proposed antenna has $32.0mm(W2+W3){\times}47.1mm$ (L3+L4+L5+L8) on a dielectric substrate of $42.5mm(W1){\times}52mm(L1){\times}1.0mm$ size. From the fabrication and measurement results, bandwidths of 158 MHz (813 to 971MHz), 630 MHz (2.10 to 2.73GHz) and 1190 MHz (4.83 to 6.02GHz) were obtained based on the impedance bandwidth. The fabricated antenna also obtained the measured gain and radiation pattern in the required triple band.

• Journal of Korea Multimedia Society
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• v.9 no.7
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• pp.854-863
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• 2006

As WiBro service providers which provide a wireless multimedia communication service are selected, the commercial service will emerge in the near future. Although the use of efficient multicast technology for multimedia will be essentially required, it would be difficult to design the overall communication network in the early stage by using IP multicast due to technological or commercial issues. Application layer multicast schemes or hybrid multicast schemes also should be considered. In this paper, we propose a hybrid multicast scheme and evaluate its performance against typical IP multicast schemes on modelling of the WiBro network for one of WiBro service providers. We also propose a simulation method for the hybrid multicast on the simulation network for performance evaluation. If the number of mobile nodes reaches a certain point, the performance difference between the hybrid multicast and IP multicast is reduced significantly. We show that hybrid multicast technology can be applied for WiBro service without much performance degradation.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.43-49
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• 2020

In spite of the notable advancements of millimeter wave communication technologies, the 60 GHz Wi-Fi is still not widespread yet, mainly due to the high limitation of coverage. Conventionally, it has been hardly possible to support a high data rate with fast beam adaptation while keeping atmospheric beamforming coverage. To solve these challenges in the 60 GHz communication system, holistic system designs are considered. we implemented an enhanced design LDPC decoder enabling 6.72 Gbps coded-throughput with minimal implementation loss, and our proposed phase-tracking algorithm guarantees 3.2 dB performance gain at 1 % PER in the case of 16 QAM modulation and LDPC code-rate 3/4.

• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.223-234
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• 2008

Mobile multi-hop relaying (MMR) technology is being considered as a promising solution capable to enhance coverage, user throughput, and system capacity of the current wired backbone dependent wireless access networks. Since the relaying nodes do not need a wired backbone access, MMR technology offers easy and low-cost deployment, flexible cell planning, and adaptive traffic handling performance. In this paper, we investigate performance and cost effectiveness of the MMR technology deployment in the IEEE802.16j based WiBro/WiMAX systems. We first introduce standardization activities and research issues of MMR WiBro/ WiMAX systems. Since the coverage extension problem may occur in metropolitan areas as well as suburban or rural areas where user density is relatively low or moderate, we introduce several MMR topologies and analyze cost-effectiveness of MMR based coverage extension with respect to the user traffic density. Then, we argue cost effect on MMR technology deployment and throughput performance, Finally, we introduce further study issues including sectorized base station based MMR deployment approaches and the single and multi-frame structure MMR approaches.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.1
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• pp.47-52
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• 2008

In this paper, the small PIFA with dual bandwidth using LTCC is the proposed. The proposed PIFA is designed and fabricated for dual resonance bands (K-PCS and WiBro). It consists of two layers. The bottom layer shape PIFA has 120MHz bandwidth (1.727 ~ 1.847 GHz), it satisfied K-PCS. The top layer shape stacked element has 110MHz bandwidth (2.302 ~ 2.412 GHz), it satisfied WiBro. The top layer is stacked on the bottom layer for electric coupling. Maximum radiation gain of K-PCS, WiBro bands are 2.11 dBi, 3.71 dBi respectively. For miniaturization of the antenna structure, the PIFA using LTCC ( ${\varepsilon}_r\;=\;8$ ) chip is fabricated. The proposed PIFA shows the effect of SAR reduction also. A defect that is fabricated by stacking up the layers in the design of PIFA is complemented by fabricated in using LTCC chip.

• Journal of Digital Contents Society
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• v.13 no.4
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• pp.477-482
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• 2012

The mVoIP service is the technology which focuses on the wireless data service as the IP network having the transmission rate of 100 Mbps classes on the high-speed middle of movement through the WiFi, WiBro and 3G mobile radio communication network, and etc. and is developed. Since 2010, the mVoIP (mobile VoIP) service shows the rapid growth due to 4G-LTE service seriously disclosed from July with the Smart phone and 2,011 it begins to be rapidly popularized. In this research, additionally the mVoIP service industry activation plan is presented with the trends of technology development including the chip-set/module/terminal, etc. based upon local and foreign market trend searchlight through the market demand analysis. The mVoIP service downloads App to the mobile apparatus and or can provide the service as the software through the WiFi network. Therefore, the change which is large in the products development aspect is to be have no. Expected to is being provided as the added service in the case of 4G-LTE as a matter of course, the service deployment where it is based on the market principle and demand needs is needed.