• Information and Communications Magazine
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• v.15 no.7
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• pp.75-94
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• 1998

In this paper, HFC CATV networks are introduced. HFC CATV networks are currently considered as a most effective and plausible solution for subscriber access networks in the information superhighway, among others such as ADSL and B-WLL. The advantages of HFC CATV networks include its broad upstream and downstream channel bandwidths, much wider than PSTN's and its readiness. The HFC CATV networks are already well spread among the general subscribers in Korea. This fact will shorten the installation period and significantly reduce its cost. In addition, The structure and channel environment of the HFC CATV networks are introduced. At the same time, in this paper included are major problems in the HFC CATV networks and the solutions for these problems. Also discussed are data transmission, medium access control, IEEE802.14, and MCNS for standardizations. Moreover, additional telecommunications service activities in both Korea and other countries, using HFC CATV networks are also included. The topics which are covered in detail are the ones such as interoperation between HFC CATV networks and trunk line and the digital transmission performance test for the CATV networks. In the performance test, it is concluded that HFC CATV networks can satisfy the QoS for various additional services if the number of the subscribers in a cell is limited to less than 500 and other minor requirements are satisfied. Based on all these discussions and conclusions, HFC CATV networks are suggested in this paper for the subscriber access networks of the so called information superhighway.

• Journal of Korea Technology Innovation Society
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• v.4 no.2
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• pp.157-171
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• 2001

This paper discusses the economics of local loop architecture focusing on existing technologies, ADSL, HFC, and new one, PLC, and suggests a new modeling approach of access network system and the numerical equations. To modelize access network system and drive the numerical equations, we consider the double star and the tree & branch architecture and made block diagram of each access system. In addition, we introduce the density of subscriber as a variable and the equation of seeking the optimal number of cell in a service area. The economics of local loop architecture is analyzed in two ways, i.e. with and without consideration of the cost of cable and infrastructure. From the numerical analysis, we find that in case of not including the cost of cable and infrastructure, there is no much difference in the cost per one subscriber, while, in case of including it, there is remarkable difference among technologies. Therefore we conclude that the economics of local loop architecture is depend on the density of subscriber and existing network infrastructures.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.456-458
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• 2001

본 논문은 가정 내나 소호용의 멀티미디어 게이트웨이 서버 시스템에 관한 것이다. 가정 내 컴퓨터 시스템의 보급률이 높아지고 그 활용에 대한 관심이 많아지고 있다. 현재는 가정 내까지 ADSL망이 들어와 있고 가정 내에나 소호에 컴퓨터 유사 시스템들이 사용되므로 이들을 연결하는 망의 구성이 필요하다 본 논문의 장비는 이러한 망의 구성과 내부에서 외부의 망으로 접근을 하는 방법을 제공할 뿐아니라 외부망에서 내부망을 접근하여 내부기기를 통제하는 서어비스에 관해서도 논한다. 또한 DVD나 DTV 등의 멀티미디어 서어비스에 관한 것도 논하기로 한다. 가정이나 소호에 관련한 장비로는 무선랜, 블루투스, HomePNA, IEEE1394, DVD, Ethernet 등으로 구성되며 PLC에 관해서도 간략하게 논하도록 한다. 이러한 멀티미디어 게이트웨이 서버는 인터넷 게이트웨이로서 뿐만아니라 서어비스 게이트웨이로서의 역할을 하게된다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1079-1084
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• 2006

Since the focus of QFD is placed on the early stage of product development, the uncertainty in the input information of QFD is inevitable. If the uncertainty is neglected, the QFD analysis results can be misleading. This paper proposes an extended version of the QFD methodology, called Robust QFD, which is capable of considering the uncertainty of the input information and the resulting variability of the output. The proposed framework aims to model, analyze, and dampen the effects of the uncertainty and variability in a systematic manner. The proposed framework is demonstrated through a case study on the ADSL-based high-speed internet service.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1525-1528
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• 2005

본 논문에서는 초고속인터넷 망에서 VoIP 서비스 제공시 적용할수 있는 망별 QoS 제공기술을 소개하고 이러한 QoS 기술들을 이용하여 통화품질을 개선할수 있는 방안을 제시하였다 . 초고속인터넷망의 QoS 기술은 적용방법에 따라 다양한데 본 논문에서는 IEEE 802.1P, IP TOS 기술, DIFFFSERV 기술, Traffic classification & Queuing, ATM QoS 기술 등을 소개하고 이러한 기술을 사용하여 초고속인터넷망중 Metro EtherNet 망, ADSL 망을 중심으로 VoIP 서비스시 성능을 향상 할 수 있는 방안을 제시하였다

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.488-491
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• 2002

This growth if WWW(World Wide Web) with the spread of ADSL provides us with a variety of service that are the extensions of opportunities to get information. a various education methods by remote courses and electronic commerce. Remote Monitoring Server(RMS) that uses internet and WWW is constructed for chip mounter. Hardware base consists of RMS, chip mounter and C/S server. In this paper, we realize the remote management system with monitoring and diagnosis function to efficiently operate chip mounter the one of PCB assembly equipment. The remote management system for chip mounter consists of RMS(Remote Monitoring Server) and C/S server. RMS manages real-time information from chip mounter through TCP/IP. RMS that utilizes real-time information informs user of the actual output the operation status of chip mounter, user of the actual output, the operation status of chip mounter, the trouble code and the trouble description.

• Electronics and Telecommunications Trends
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• v.17 no.4 s.76
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• pp.75-80
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• 2002

본 고에서 저자는 신규 통신 서비스로서 공중 무선 LAN 서비스의 수요 예측에 대해 다룬다. 신규 사업에 있어서 수요 예측은 사업의 수익성을 평가하는 가장 기본적인 자료이며 효과적인 마케팅 전략 수립을 위한 기초 단계로서 의미가 크다. 그러나 신규 서비스는 특성상 과거의 판매 자료가 존재하지 않기 때문에 시계열 자료를 이용한 수요 예측이 불가능하다. 따라서 본 고에서는 공중 무선 LAN 서비스와 유사한 특성을 지닐 것으로 판명되는 기존 서비스인 ADSL/케이블모뎀 서비스와 이동전화 서비스의 과거의 확산 과정을 분석하여 공중 무선 LAN 서비스의 확산 과정을 살펴본다. 이러한 유사추론과정을 통해 2006년까지 공중 무선 LAN 서비스의 가입자 수를 예측한다. 또한 선택모형(choice model)을 이용한 잠재 시장 규모의 추정법에 대해 언급한다.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2000.11a
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• pp.45-67
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• 2000

Broadband access technologies plays an important role in the national information infrastructure. In the evolution path of the information infrastructure, the relative economics of alternative access technology is the most critical determining factor. In this paper, we discuss the economics of local loop access technologies of existing technologies, such as, ADSL, HFC, and new PLC. To do this, we suggest appropriate configuration of access network system and its associated numerical equations. To modelize access network system and drive the numerical equations, we consider the DS (Double Star) and the T&B (Tree ＆ Brench) architecture and analyse the adequate block diagram of each access system for each technology We introduce the density of subscriber as a key variable and the equation of allocating optimal number of cell in a service area. We analyze the relative economics of local loop architecture in two different situations, that is, urban and rural. From the empirical implementation, we found that for the case of urban area, where the cost of cable and infrastructure is not necessary, there is not much difference in the cost per one subscriber. However, for the case of rural region, we found that there is remarkable difference in the cost per one subscriber among technologies. Therefore we conclude that the economics of local loop architecture is depend on the density of subscriber and existing network infrastructures. we hope that this paper contribute to the optimal technology selection of consmer, technology Providers, and government.

• Information and Communications Magazine
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• v.16 no.10
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• pp.112-124
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• 1999

본 논문에서는 FTTC/VDSL (Fiber-to-the-Curb/Very High-speed Digital Subscriber Line) 전송시스템의 개발동향과 ANSI, ETSI, ITU등의 표준화 위원회에서 현재 진행중인 VDSL 시스템의 표준화 작업에 대해 기술하였다. 특히, POTS (Plain Old Telephone Service), BA-ISDA(Basic Access Integrated Services Digital Network), HDSL(High-rate Digital Subscriber Line), SDSL (Single-pair HDSL), ADSL(Asymmetric Digital Subscriber Line) 등의 다양한 xDSL (Digital Subscriber Line) 서비스들에서 발생하는 NEXT (Near-end Crosstalk)/FEXT (Far-end Crosstalk)와 같은 crosstalk를 최소화하기 위해 제안된 VDSL시스템의 주파수 대역과 PSD (Power Spectral Density) mask에 관해 설명하고, 순방향(down-stream) 채널과 역방향(upstream) 채널의 데이터 전송률이 대칭적인 VDSL전송시스템과 비대칭적인 VDSL 전송시스템 간의 주파수대역의 호환성 문제, RFI(Radio Frequency Interference) ingress/egress 문제의 해결 방안에 관해 기술하였다. 또한, 현재 VDSL Coalition과 VDSL Alliance 간에 논의 중인 VDSL 전송시스템의 변복조 방식에 관한 표준화 작업과정 및 순방향과 역방향에 할당될 band 개수에 따른 시스템 성능의 장단점 등에 관해 살펴보았다. 끝으로 현재 국내에서 개발되고 있는 FTTC/VDSL 전송시스템의 전체구조를 요약하고, 네트워크에서 가입자쪽으로 순방향 데이터 전송에 사용된 51.84 Mb/s 19-CAP (Carrierless Amplitude/Phase Modulation) 전송시스템과 가입자 댁내에서 네트워크 방향으로 역방향 데이터 전송에 사용된 1.62 Mb/s QPSK (Quadrature Phase Shift Keying) burst-mode TDMA (Time Division Multiple Access) 전송시스템 등의 동작 원리 및 구조를 기술하였다.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.71-78
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• 2005

Nowadays, the demand of HPI(High-speed Portable Internet) has been gradually increased to support the various services of high speed wire line internet such as xDS. HPI can support high speed internet in anyplace, anytime. For successful development of HPI, the performance should be evaluated according to the cell size and/or the number of users and cell design should be carried out based on these criteria. The previous cellular systems using CDMA technique focus on the establishment of link based on power control but HPI systems consider the QoS (Quality of Service) and its performance based on the scheduling technique. The results from the system level simulation show that the throughput is sensitive to the cell size and the number of users has little impact on it. Moreover, the variation of service delay is more sensitive to the number of users but less to the cell size.