VDSL (Very-high Rate Digital Subscriber Line) - System Level Issues and Implementation

Gi-Hong Im 에스케이텔레콤 (주) 1997 Telecommunications Review Vol.7 No.2

현재 우리나라와 선진 각국에서 시험 서비스 중인 ADSL(Asymmetric Digital Subscriber Line) 시스템은, 기존 모뎀(최대속도 56 Kb/s)과는 다르게 현재 사용 중인 전화선이나 전화기를 그대로 사용하면서도 최대 약 10 Mb/s 의 고속데이터통신이 가능할 뿐 아니라 데이터통신과 일반전화를 동시에 이용할 수 있는 것이 특징이다. 최근에는 데이터 전송속도를최대 51.84 Mb/s 까지 높일 수 있는 고속 전송 시스템인 VDSL 시스템에 관한 연구와 표준화 작업이 활발히 진행되고 있다. VDSL 시스템은 전화국과 가입자간의 거리가 짧고 가입자가 밀집된 지역에 서비스되며, 앞으로 보편화될 FTTC (Fiber-to-the-Curb) 구조에서 ADSL 시스템을 대체할 차세대 고속전송시스템이다. 본 논문에서는 현재 표준화되고 있는 VDSL 시스템의 중요한 시스템 이슈를 간략히 요약한 후에, 표준 전송방식으로 제안된 CAP(single carrier)방식과DMT(multicarrier) 방식을 표준화 위원회에서 규정한 몇 가지 기준에 의거하여 성능을 비교분석한다. VDSL 시스템을 위한 표준 전송방식은 올해 말쯤 결정될 예정이다. 본논문은 최근 ANSI T1E1.4 에 발표된 두 논문을 요약 정리한 것이다[1],[2]. 참고로, 16-CAP 전송방식 [3]과 64-CAP 전송방식[4]은 IBM이 제안한 Partial-Response Class IV 전송방식[5]과 약 3 년여의 치열한 경합끝에 ATM Forum의 51.84Mb/s [6]와 155.52Mb/s [7] ATM-LAN 표준전송방식으로각각 채택되었으며, FTTC(Fiber-to-the-Curb)구조에서 DAVIC이 규정한 51.84/25.92/12.96 Mb/s 표준 전송방식이다[8],[9]. DMT 전송방식은 ANSI T1E1.4 가 규정한 ADSL 시스템의 표준전송방식이며[10], 현재 CAP 전송방식을 이용한 RADSL(Rate-Adaptive Digital SubscriberLine) 표준화작업이 진행중이다[11].

Performance Analysis of Cyclostationary Interference Suppression for Multiuser Wired Communication Systems

Im, Gi-Hong,Won, Hui-Chul The Korea Institute of Information and Commucation 2004 Journal of communications and networks Vol.6 No.2

This paper discusses cyclostationary interference suppression for multiuser wired communication systems. Crosstalk interference from digital signals in multipair cables has been shown to be cyclostationary. Many crosstalk equalization or suppression techniques have been proposed which make implicit use of the cyclostationarity of the crosstalk interferer. In this paper, the convergence and steady-state behaviors of a fractionally spaced equalizer (FSE) in the presence of multiple cyclostationary crosstalk interference are thoroughly analyzed by using the equalizer's eigenstructure. The eigenvalues with multiple cyclostationary interference depend upon the folded signal and interferer power spectra, the cross power spectrum between the signal and the interferer, and tile cross power spectrum between the interferers, which results in significantly different initial convergence and steady-state behaviors as compared to the stationary noise case. The performance of the equalizer varies depending on the relative clock phase of the symbol clocks used by the signal and multiple interferers. Measued characteristics as well as analytical model of NEXT/FEXT channel are used to compute the optimum and worst relative clock phases among the signal and multiple interferers.

[특집/기술해설] Carrierless AM/PM Modulation and Its Applications for HDSL/ADSL, ATM LAN and Broadband Interactive Multimedia

Gi-Hong Im 대한전자공학회 1994 텔레콤 Vol.10 No.2

Carrierless Amplitude Modulation/Phase Modulation(CAP) is a bandwidth-efficient two-dimensional passband line code that was originally derived from the closely related quadrature amplitude modulation (QAM) line code. CAP transceivers are particular]y well suited to all-digital implementations for applications where the bandwidth of the signal's spectrum is of the same order of magnitude as the center frequency of the spectrum. CAP has the same spectral characteristics and provides the same theoretical performance as QAM, but is generally less complex to implement digitally. The purpose of this paper is to provide an introduction to the design of digital CAP transceivers, with emphasis on the high-rate digital subscriber line(HDSL), asymmetric digital subscriber line(ADSL), high-speed local area network(LAN), and broadband interactive multimedia applications. We present experimental results of the CAP HDSL and ADSL transceivers. In order to get the full trellis coding gain without sacrificing any of the decision feedback equalizer(DFE) gain, we use Tom]inson precoding by which the feedback filter of the DFE is transposed into the transmitter HDSL CAP system. We have implemented an ADSL transceiver prototype using 64-CAP and 16-CAP line codes for the 1.544 Mb/s down-stream and 24.5 kb/s upstream channels, respectively. The perfomlance results of the ADSL CAP transceivers in the presence HDSL architecture.<br/>

관료집단에 대한 통제력이 정책결정과정에 미치는 영향: 김대중 정부와 노무현 정부의 대북정책 비교

임기홍 ( Im Gi Hong ) 서강대학교 동아연구소 2014 東亞 硏究 Vol.33 No.1

본 논문은 김대중 정부와 노무현 정부의 대북정책결정과정을 비교 분석함으로써, 최고지도자를 포함한 집권세력의 관료에 대한 통제력이 그 성과에 핵심적인 결정요인임을 밝히는데 그 목적이 있다. 특히 대북정책을 분석하는 기존의 논의가 대통령의 리더십 스타일에 초점을 맞추거나 대통령과 관료집단 간 상호작용을 기술하는 데에만 그쳤다면, 본 연구는 관료집단에 대한 통제력을 구성하는 요소들, 그 중에서도 ‘매개인사’의 활용에 주목함으로써 보다 분석적인 사례연구를 수행하고자 한다. 이 글에서 제시하는 ‘매개인사’는 기존 조직에 상당한 지분을 가지고 있어 느슨하게나마 “해당 부처에 대한 통제력을 유지하면서도 대통령의 정책 의지 실현에 기여할 수 있는 인사”를 뜻하며, ‘내부승진’이 아닌 ‘외부인선’을 통해 주로 임명된다. 관료에 대한 통제와 개혁 의지의 실현이란 목표 간 상쇄관계(Trade-off)를 극복하기 위한 대안으로서 ‘매개인사’를 제시한 것이다. 그런데 이들의 개인적 역량이 출중하더라도 집권세력의 정치적 능력이 뒷받침되지 못한다면 ‘매개인사’로서의 역할 수행에는 한계가 있을 수밖에 없으며, 따라서 대통령의 철학과 신념, 집권세력의 응집력, 제도적 기반, 넓은 인재pool 등의‘매개인사 활용능력’이 반드시 전제되어야 한다. 본 논문은 대북정책결정과정에서 관료집단에 대한 통제력을 확보하는 것이 정책의 성패를 결정하는 핵심 요인임을 밝히고, 그러한 통제력을 구성하는 요소들을 개념화했다는 점에서 그 학문적 의의를 가진다. 특히 정치권력과 관료권력 간 갈등, 부처별 정책선호의 차이로 인한 갈등 등이 단지 대외정책결정과정에서만 발생할 수 있는 문제는 아니란 점에서 그 정치학적 의미는 향후 더욱 계발될 수 있을 것으로 보인다. 아울러, 향후 개혁적 기조를 지닌 정치세력이 집권할 시, 정치적 능력의 신장을 통해 관료집단에 대한 통제력을 제고하는 한편, 대통령의 정책기조를 관료들에게 설득하는 동시에 개혁을 수행토록 할 수 있을 만큼의 전문성, 경력 그리고 신망을 두루 갖춘 중량감 있는 매개인사를 다수 확보해야 한다는 실천적 함의 또한 제시될 수 있을 것이다. This paper aims to examine if the controls over the ruling bureaucrats, by the ruling forces including the president, could be the core determining factor for their policy achievements, through a comparative study on the policy-making process of the Kim Dae-Joong and Roh Mu-hyun administration. Moreover, this provides new factors which can contribute to the effective controls over bureaucrats, criticizing that the existing discussions about the policies towards North Korea have focused merely on the presidents` leaderships or have superficially described the interaction between presidents and bureaucrats. One of the key measure for ruling forces to effectively control bureaucrats is a ‘powerful mediator.’ In fact, the trade-off between the control over bureaucrats and the realization of the policy intention could be generated, depending on whether a minister gets promoted from within the ministry or selected from outside of the organization. Then, a ruling force would be encouraged to employ a ‘powerful mediator’ who can minimize those trade-off and connects itself harmoniously with bureaucrats. if it holds the resources for the employment. This is because the appropriate employment of ‘powerful mediators’ can help a ruling force to bring good policy performances. This paper would be meaningful in clarifying that the success of policies depends on procuring control power towards bureaucrats and in conceptualizing the new factors which compose it, especially the ‘powerful mediator.’ In particualr, besides North Korea Policy, the conflict between the political and bureaucratic power as well as a certain tension generated from the differences in the preferences of each ministries could be seen also in other policy-making arena. Hence, a ruling forces is required to secure a plenty of ‘powerful mediators,’ who are qualified with the expertise and confidence to persuade the president`s policy stance to bureaucrats and correspondingly induce them to implement even the reform against their own interests.

FDM 방식 3D 프린터에 대한 딥러닝 기반 물성 추정

임주현(Joo Hyeon Im),김원곤(Wongon Kim),안성훈(Sung-Hoon Ahn),윤병동(Byeng Dong Youn) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Additive manufacturing (AM) is playing a major role in Industry 4.0. AM can simplify the fabrication of complex shapes while minimizing manufacturing time and cost. However, the poor surface quality and weak mechanical properties of the output hinder the broad application of AM. In this study, we propose a deep learning-based method for estimating the mechanical property in a fused deposition modeling-type 3D printer. Acceleration signals were acquired in the process of outputting a tensile specimen through construction of a test-bed. In addition, a tensile test was performed using the specimen to collect information on mechanical properties. After that, features were extracted from the divided signals to analyze the correlation with the mechanical properties. Finally, the quality of highly correlated property was estimated through deep neural network. We confirmed that deep learning-based method is good at estimating property through mean square error loss and root mean square error.

스마트그리드환경에서 OTP기반의 AMI인증방식에 관한 연구

김홍기 ( Hong-gi Kim ),홍민 ( Min Hong ),이임영 ( Im-yeong Lee ) 한국정보처리학회 2011 한국정보처리학회 학술대회논문집 Vol.18 No.2

스마트그리드는 기존의 전력망 환경에 정보통신 기술을 접목하여 발전소와 사용자가 실시간으로 정보를 교환하며, 사용 과금 및 전력공급의 효율성을 증대시키는 기술이다. 스마트그리드는 전력관리소인 MDMS(Meter Data Management System)와 각 가정에 연결되어있는 스마트미터와의 통신을 통해 전력데이터를 수집하게 되는데, 각 가정의 디바이스들은 전력사용량을 사용한 만큼 스마트미터에게 정보를 전송하여 스마트미터에서는 그 정보를 MDMS에게 전송하는 방식을 사용하고 있다. 이는 네트워크를 활용하여 전송하고 있기 때문에 기존의 보안위협 및 스마트그리드환경에서의 추가적인 보안위협이 예상된다. 따라서 본 논문에서는 각 가정에서 측정한 전력데이터 값을 안전하게 전송하기 위해 디바이스를 OTP를 기반으로 안전하게 인증하는 기술에 대하여 제안하였다.

스마트그리드환경에서 안전한 전력량 전송을 위한 AMI 인증기법

김홍기 ( Hong-gi Kim ),홍민 ( Min Hong ),이임영 ( Im-yeong Lee ) 한국정보처리학회 2011 한국정보처리학회 학술대회논문집 Vol.18 No.1

최근 기존의 단 방향 전력망 시스템에 IT기술을 접목한 스마트그리드 기술의 개발이 활발하게 이루어지고 있다. 스마트그리드의 핵심 인프라로 원격검침시스템인 AMI는 스마트미터에서 측정한 전력량을 상위 데이터 저장소인 MDMS에 전송한다. 스마트미터는 IT기술을 활용하여 전력데이터를 전송하고 있기 때문에 기존 보안위협을 포함한 추가적인 보안위협이 예상된다. 이는 소비자의 개인정보노출 및 산업시스템 마비 등의 손실이 발생할 가능성이 있다. 따라서 이러한 보안위협에 대응하기 위해 스마트 그리드 환경에서 스마트미터와 MDMS간 상호인증과 데이터 전송방식에 관하여 제안하였다.

Cardiovascular and Gastrointestinal Effects of Etoricoxib in the Treatment of Osteoarthritis: A Systematic Review and Network Meta-analysis

( Dam Kim ),( Soo-kyung Cho ),( Seoung Wan Nam ),( Hyuk Hee Kwon ),( Sun-young Jung ),( Chan Hong Jeon ),( Seul Gi Im ),( Dalho Kim ),( Eun Jin Jang ),( Yoon-kyoung Sung ) 대한류마티스학회 2017 대한류마티스학회지 Vol.24 No.5

Objective. To estimate the cardiovascular (CV) and gastrointestinal (GI) risks of etoricoxib in the treatment of osteoarthritis (OA) compared to a placebo and other non-steroidal anti-inflammatory drugs (NSAIDs). Methods. A systematic review of randomized, controlled trials (RCTs) of etoricoxib were performed. Bayesian network meta-analysis was used over a duration of 12 weeks. The incidence of CV and GI events for a duration ≥26 weeks were also tabulated and presented using descriptive statistics. Results. From this search, 10 studies were identified. Of these, 6 and 5 RCTs that measured the CV and GI events at 12 weeks were included in meta-analysis. They showed that etoricoxib did not increase the CV events compared to the placebo or NSAIDs during the 12 week period (odds ratio [OR]=0.59 compared to celecoxib, OR=0.89 with ibuprofen, OR=0.70 with placebo, and OR=2.16 with naproxen). The risk of GI events was comparable to that of most comparators, with the exception of naproxen, which had a significantly lower risk of GI events (OR=0.18) during the 12 week period. For a duration ≥26 weeks, the incidence of CV and GI events with etoricoxib increased with increasing duration. Conclusion. Etoricoxib is an alternative short-term treatment option for OA, showing comparable CV and GI complications to other NSAIDs. Nevertheless, further studies will be needed to elucidate the long-term safety of etoricoxib in the treatment of OA. (J Rheum Dis 2017;24:293-302)

Characterization of Cement Solidification for Enhancement of Cesium Leaching Resistance

Gi Yong Kim,Won-Hyuk Jang,Sung-Chan Jang,Junhyuck Im,Dae Seok Hong,Chel Gyo Seo,Jong Sik Shon 한국방사성폐기물학회 2018 방사성폐기물학회지 Vol.16 No.2

Currently, the Korea Atomic Energy Research Institute (KAERI) is planning to build the Ki-Jang Research Reactor (KJRR) in Ki-Jang, Busan. It is important to safely dispose of low-level radioactive waste from the operation of the reactor. The most efficient way to treat radioactive waste is cement solidification. For a radioactive waste disposal facility, cement solidification is performed based on specific waste acceptance criteria such as compressive strength, free-standing water, immersion and leaching tests. Above all, the leaching test is important to final disposal. The leakage of radioactive waste such as 137Cs causes not only regional problems but also serious global ones. The cement solidification method is simple, and cheaper than other solidification methods, but has a lower leaching resistance. Thus, this study was focused on the development of cement solidification for an enhancement of cesium leaching resistance. We used Zeolite and Loess to improve the cesium leaching resistance of KJRR cement solidification containing simulated KJRR liquid waste. Based on an SEM-EDS spectrum analysis, we confirmed that Zeolite and Loess successfully isolated KJRR cement solidification. A leaching test was carried out according to the ANS 16.1 test method. The ANS 16.1 test is performed to analyze cesium ion concentration in leachate of KJRR cement for 90 days. Thus, a leaching test was carried out using simulated KJRR liquid waste containing 3000 mg·L-1 of cesium for 90 days. KJRR cement solidification with Zeolite and Loess led to cesium leaching resistance values that were 27.90% and 21.08% higher than the control values. In addition, in several tests such as free-standing water, compressive strength, immersion, and leaching tests, all KJRR cement solidification met the waste acceptance or satisfied the waste acceptance criteria for final disposal.

酸性비의 pH變化에 대한 影響因子 硏究

任齊彬,金美淑,洪雄基 全北大學校 附設 都市및環境硏究所 1994 都市 및 環境硏究 Vol.9 No.1

The primary pollutants can be converted to acid aerosol or gases by complicated chemical mechanisms which would be scavenged from the atmosphere by the wet and dry deposition. This study is to investigate the factors of rain-water acidity thrugh the correlation between the major chemical components in precipitation process. The results were as follows: 1. PH range of rain-water are 4.26- 6.90. 2. Correlation between [Ca^2+] and [NO_3^-], [Ca^2+] and [SO_4^2-], [Ca^2+] and [cb-ca] are 0.70, 0.86, 0.93, respectively. 3. Correlation between [Na^+] and [CI^-] is 0.83. 4. Correlation between [NH_4^+] and [CI^-], [NH_4^+] and [NO_3^-], [NH_4^+] and [SO_4^2-], [NH_4^+] and [cb-ca] are 0.73, 0.87, 0.71, respectively. 5. Correlation between [cb-ca] and [SO_4^2-] which is calculated from charge balance equation is 0.79. And it seems that [cb-ca] influenced to the pH change, initially [SO_2] absorbed in rain-water. 6. Concentration of [SO_4^2-] increases, by the gaseous reaction of SO_2 oxidation in the period of no-rain-days, and the aqueous reaction in the rain-water. 7. [SO_4^2-]/[NO_3^-]=5 in Chonju, the value of that was 1.32 in Seoul. 8. The factors of pH change are [SO_4^2-] and [cb-ca], especially at the condition of pH < 5.