• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.593-595
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• 2001

Zinc-phosphate glasses에 B$_2$O$_3$를 도입하여 borate, phosphate, boro-phosphate networks가 혼재되어 있는 highly cross-linked structures를 형성시켜 Phosphate glasses의 화학적 안정화를 검토하였다. Raman 측정 결과 B$_2$O$_3$와 P$_2$O$_{5}$는 잘 혼화된 polynary networks를 이루고 있으며, 이렇게 하여 증진된 구조적 cross-linking에 의하여 xB$_2$O$_3$.(1-x)Zn$_2$P$_2$O$_{7}$ glasses의 T$_{g}$, T$_{d}$는 증가하였고 동시에 CTE는 감소하는 결과를 가져왔다.

• Electronics and Telecommunications Trends
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• v.37 no.4
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• pp.46-59
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• 2022

The 5G MEC (Multi-access Edge Computing) technology offers network and computing functionalities that allow application services to improve in terms of network delay, bandwidth, and security, by locating the application servers closer to the users at the edge nodes within the 5G network. To offer its interoperability within various networks and user equipment, standardization of the 5G MEC technology has been advanced in ETSI, 3GPP, and ITU-T, primarily for the MEC platform, transport support, and MEC federation. This article offers a brief review of the standardization activities for 5G MEC technology and the details about the system architecture and functionalities developed accordingly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.760-770
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• 2011

The existing mobility management schemes do not fully support the next generation network, which is composed of IP-based core network and various access networks. Currently, ETRI has been developing the AIMS (Access Independent Mobility Service) system which satisfies the ITU-T requirements of mobility management in the next generation network. The AIMS system is designed to provide a mobile host with a fast and reliable mobility service among heterogeneous access networks. Recently, many user devices have multiple communication interfaces, e.g., 3G and WLAN, and thus they can make two or more network connections at the same time. In this paper, we design a scheme of flow mobility, i.e., the movement of selected data flows from one access technology to another, to be applied in the AIMS system, and verify the proposed scheme through the NS-3 simulation study. From the simulation results, we can know that the proposed flow mobility scheme can utilize the network resource efficiently in the heterogeneous mobile networks.

• Journal of the Korea Society for Simulation
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• v.13 no.3
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• pp.31-41
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• 2004

In this paper, we consider the strategy of Universal Mobile Telecommunication System (UMTS) and Wireless Local Area Network (WLAN) internetworking that provide the seamless vertical handover for mobile nodes. We propose Mobility Anchor Points (MAP) based UMTS/WLAN internetworking architecture to support the vertical handover. Also, on integrated UMTS/WLAN networks, we propose a vertical handover scheme that avoids the call blocking caused by the network resource shortage. We provide the numerical analysis to investigate the performance evaluation to the proposed scheme and compare the proposed scheme with the existing scheme.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.19-24
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• 2023

Recently, fifth generation (5G) networks are being deployed in phases all over the world, the paradigm has shifted to developing the next generation wireless technologies, which have grown exponentially in last few decades, wireless networks are promising for the demand to enormous connections. Non-orthogonal multiple access (NOMA) and intelligent reflecting surface (IRS) are considered as the key technoloies for next-generation beyond 5G (B5G) and sixth generation (6G) networks, in which IRS can play an important advance in the wireless propagation environment, and NOMA can effectively increase massive connectivity to improve user fairness. In this paper, we analyze a performance on the strongest channel user in terms of achievable data rates numerically. Then, with the achievable data rates, the signal-to-noise ratio (SNR) gain is calculated for the IRS-NOMA network over the conventional NOMA network. As a consequence, IRS-NOMA schemes have been considered as some key technologies.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.8
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• pp.35-43
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• 2004

An AAL2 transmission scheme is used to deliver voice and data traffic between Node-B and RNC on 3G WCDMA network. To predict performance of AAL2 multiplexing precisely, we derived analytically bandwidth gain and cell packing density using discrete-time Markov chain model for voice service and validated these results with simulation. We also performed detailed simulation for AAL2 multiplexing in a concentrator. Based on the analytical result, we propose the engineering guideline to select the optimal Timer_CU in a Node-B. We found that there is no major benefit of additional AAL2 multiplexing in a concentrator and the benefit of AAL2 switching in tub for data services is much less than that for voice service.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.81-86
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• 2008

The paradigm of information & communication is rapidly changed into ubiquitous environment based electromagnetic wave, and antenna technology in the wireless ubiquitous communication is remarkably developed. Mini chip antenna has its within small card compared to the external AP antenna. Designed and Fabricated WLAN antenna has a broadband characteristics of 2.4~2.5GHz and 4.9~5.85GHz, and can be used triple mode of IEEE 802.11.a,g.b, and it has comparatively a constant performance in the dual frequency band.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.123-132
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• 2005

By complementary integration of WLAN and UMTS, a Beyond third Generation(B3G) mobile network can be constructed to establish the fastest global roaming environments, There are 2 types of B3G networks: loosely-coupled and tightly-coupled, A tightly-coupled network demands lots of investment and considerable amount of time to construct. On the other hand a loosely-coupled network is more scalable and easier to implement than a tightly-coupled one, But it has critical drawbacks of packet loss and blocking of services due to handover delay, To alleviate these drawbacks this thesis proposes a vertical handover procedure between WLAN and UMTS, which is based on MAP of HMIPv6, Performance of the proposal is evaluated in terms of blocking probabilities, The proposed procedure based on HMIPv6 shows better performance than those based on MIP.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.3
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• pp.46-52
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• 1998

In this paper, after inputting the computer with the attached number plate on the vehicle, using it, the color decomposition method and back propagation neural network proposed the extractable method of the vehicle number plate at high speed. This method separated R, G, B signal form input moving vehicle image to computer through video camera, then after transform this R, G, B signal into input image data of the computer by using color depth of vehicle number plate and store up binary value in the memory frame buffer. After adapting character's recognition algorithm, also improving this, by adapting back propagation neural network makes the vehicle number plate recognition system. Also minimalizing the similar color's confusion, adapting horizontal and vertical extracting algorithm by using the vehicle's rectangular architecture shows the extract and character's recognition of the vehicle number plate at high speed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.8
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• pp.510-517
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• 2014

Recently, Cable communications services are becoming the HDTV to 3DTV, UHDTV broadcasting and 100Mbps to 1Gbps Internet. however existing technologies are limited to provide high-quality broadband services in the HFC network. The network upgrade technologies have some problems that Up/Downsteam frequency extension, Cost of upgrading by using DOCSIS3.1, EPOC and Legacy STB compatibility, Cost of upgrading the network by RFoG, RF overlay PON. This paper propose the RF/PON based gigabit Transmission system in order to provide the 1Gbps internet without using frequency and the Multiscreen to IP devices. After the proposed RF/PON system was developed and implemented, this paper evaluate the performance of RF/PON system for simultaneously real-time braodcasting and 1Gbps internet, Multiscreen service, and so on.