• Journal of Digital Contents Society
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• v.2 no.1
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• pp.31-40
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• 2001

Currently there are many standards of network management. They are: SNMP(Simple Network Management Protocol - for Internet management), CMIP(Common Management Information Protocol - standardized by ITU-T and ISO), RMON(Remote network MONitoring - for distributed management of the LAN segment), and so on. Especially RMON has created the many concerns in order to manage subnetworks of a large network, but it has negative aspects. For instance, routers or hubs with RMON capability are expensive to a network manager because of adding heavy management cost. Moreover it imposes a heavier burden on network manager, because it must use a network management tool which will be additionally needed with RMON device. This paper proposes a model of PC based RMON Agent system. The RMON Agent system monitors the traffic on LAN segment through the use of a Virtual Device Driver(VxD), based on PC. In term of cost this model will replace the expensive RMON device, and eventually enable a network manager to manage LAN segment more efficiently, due to reduced cost.

• Steel and Composite Structures
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• v.27 no.6
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• pp.661-674
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• 2018

Seismic excitations may impart a significant amount of energy into structures. Modern structural design attitudes tend to absorb some part of this energy through special dissipaters instead of heavy plastic deformations on the structural members. Different types of dissipater have been generated and utilized in various types of structures in last few decades. The expected earthquake damage is mainly concentrated on these devices and they may be replaced after earthquakes. In this study, a low-cost device called energy dissipative steel cushion (EDSC) made of flat mild steel was developed and tested in the Structural and Earthquake Engineering Laboratory (STEELab) of Istanbul Technical University (ITU). The monotonic and cyclic tests of EDSC were performed in transversal and longitudinal directions discretely. Very large deformation capability and stable hysteretic behavior are some response properties observed from the tests. Load vs. displacement relations, hysteretic energy dissipation properties as well as the closed form equations to predict the behavior parameters are presented in this paper.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.04a
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• pp.65-69
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• 1999

Switching System(이하 교환 시스템)이 QoS(Quality of Service)를 유지하면서 처리 가능한 최대 동시 호처리 능력을 검증하기 위하여, 수학적 분석을 이용한 해석적 방법, 실제 호를 사용한 통계적 방법 등이 제안되었다. 해석적 방법을 이용해 산출한 교환 시스템의 최번시 동시 호 처리능력(BHCA, Busy Hour Call Attempt)은 단지 수학적인 예측일 뿐이므로 이를 검증하기 위해서 가상 호 발생기가 제안되었다. 이 가상호 발생기는 가입자의 행동을 시스템 하위 프로세서(가입자 정합 Device 제어 프로세서)에서 Simulation하여 가상의 호를 발생시키고, 이를 통해 교환기 최대 동시 호 처리 용량을 시험하기 위한 SW이다. 이 가상호 발생기는 동일한 형태의 호를 동시에 다량으로 발생시킴으로써 교환 시스템의 주 프로세서(Main Processor, MP)의 동시 호 처리 용량을 시험하기 위한 SW이다. ITU-T 권고에 의하면 시스템부하가 90~95%를 넘어 서는 경우는 예외적인 처리(과부하 제어 등)를 권고하고 있으므로 MP 부하 90~95%에서 BHCA를 계산하면 최대 호 처리 용량이라 할 수 있다. 가상 호 발생기는 시스템 개발 초기에 실제 가입자 정합 Device 와 호 발생기 없이도 MP 과부하 지점까지 호를 발생시킴으로써 개발의 시간 및 비용을 절약할 수 있도록 하고, 계획된 시스템 용량을 만족하기 위해 필요한 조치를 교환 시스템 개발 초기에 취할수 있도록 한다. 또한, 과부하 지점에서 MP가 정상 동작하는지 검증하는 도구로 사용 가능하다. 앞으로 이를 더 발전시키면 가상호 발생기를 이용한 다양한 시스템 검증 및 분석에 이용할 수 있을 것이다. 본 논문은 가상호 발생기의 구조와 최대 용량 시험 방법을 소개하고, 더 나아가 호 Traffic에 대한 최대 용량 시험뿐 아니라 QoS를 향상시키기 위한 교환 시스템의 제반 성능 시험 및 분석에 이를 이용하기 위해 개선이 필요함을 서술하고자 한다.

• Journal of the Semiconductor & Display Technology
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• v.13 no.1
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• pp.109-112
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• 2014

H.264/AVC is an international video coding standard that is established in cooperation with ITU-T VCEG and ISO/IEC MPEG, which shows improved code and efficiency than the previous video standards. Motion estimation using various macroblock from 44 to 1616 among the compression techniques of H.264/AVC contributes much to high compression efficiency. Generally, in the case of small motion vector or low complexity about P slice is decided $P16{\times}16$ mode encoding method. But according to circumstances, macroblock is decided $P16{\times}16$ mode despite large motion vector. If the motion vector variance is more than threshold and final select mode is $P16{\times}16$ mode, it is switched to $P8{\times}8$ mode, so this paper shows that the storage capacity is reduced. The results of experiment show that the proposed algorithm increases the compression efficiency of the H.264/AVC algorithm to 0.4%, even reducing the time and without increasing complexity.

• Current Optics and Photonics
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• v.2 no.3
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• pp.233-240
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• 2018

We proposed a two-mode fiber (TMF) design that can effectively reduce the mode overlap between $LP_{01}$ and $LP_{11}$ modes by using a W-shaped index profile core structure, which is a primary concern in uncoupled mode division multiplexing (MDM). TMF has a three-layered core structure; central circular core, inner cladding, and outer ring core. We confirmed that in an optimal structure the $LP_{01}$ mode was highly confined to the central core while the $LP_{11}$ mode was guided along the outer ring core to result in a minimum overlap integral. We used a full-vectorial finite element method to estimate effective index, differential group delay (DGD), confinement loss, chromatic dispersion, and mode overlap controlling the parameters of the W-shaped structure. The optimized W-profile fiber provided optical characteristics within the ITU-T recommended standards over the entire C+L band.

• ETRI Journal
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• v.38 no.1
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• pp.1-8
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• 2016

A large incoherent crosstalk (IC) caused by amplified spontaneous emission (ASE) noise power from Tx-disabled optical network units and a differential path loss has been shown to degrade upstream transmission performance in time-division multiplexing passive optical networks. This paper considers the IC-induced power penalty of an upstream signal both in an XG-PON and in a TWDM-PON. We investigate the degradation of the extinction ratio and relative intensity noise through a simulation and experiments. For the XG-PON case, we observe a 9.6 dB difference in the level of ASE noise power from Tx-disabled ONUs (hereafter known simply as ASE noise) between our result and the ITU-T XG-PON PMD recommendation. We propose an optical filtering method to mitigate an IC-induced power penalty. In the TWDM-PON case, the IC-induced power penalty is naturally negligible because the ASE noise is filtered by a wavelength multiplexer at the optical line terminal. The results provide design guidelines for the level of ASE noise in both XG-PONs and TWDM-PONs.

• ETRI Journal
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• v.31 no.2
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• pp.182-192
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• 2009

Rain attenuation and intercell interference are two crucial factors in the performance of broadband wireless access networks such as local multipoint distribution systems (LMDS) operating at frequencies above 20 GHz. Power control can enhance the performance of downlink CDMA-based LMDS systems by reducing intercell interference under clear sky conditions; however, it may damage system performance under rainy conditions. To ensure robust operation under both clear sky and rainy conditions, we propose a novel power-control scheme which applies an adaptive neuro-fuzzy inference system (ANFIS) for downlink CDMA-based LMDS systems. In the proposed system, the rain rate and the number of users are two inputs of the fuzzy inference system, and output is defined as channel quality, which is applied in the power control scheme to adjust the power control region. Moreover, ITU-R P.530 is employed to estimate the rain attenuation. The influence of the rain rate and the number of users on the distance-based power control (DBPC) scheme is included in the simulation model as the training database. Simulation results indicate that the proposed scheme improves the throughput of the DBPC scheme.

• East Asian Journal of Business Economics (EAJBE)
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• v.5 no.3
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• pp.33-40
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• 2017

Purpose - This paper suggests approaching methods for a way of strategies for traditional market extend and new ebusiness, market development, and plan of new product in the future and develop a way of method for cooperation through analysis on the smart phone market trend in different culture, effectively. Research design, data, methodology - As research design, data, and methodology, this paper suggests new idea and approaches from comparing characteristics analysis of smart phone market in different culture in AEC. This paper takes data to analysis from ITU, World Bank, AEC, and IMF. These organizer's data can be trusted as official society in the world. This paper can prove market and the characteristics of society through the corresponding results. Results - This paper can suggest the novel idea on market development and the big possibility depend on ACE country and can describe the possibility on new market because of low smart phone market penetration and low digital market penetration. Conclusions - This paper concludes to develop e-business, culture friendly ship, linking with education, development of appropriate technology depend on country, and should develop new strategy for market extend to low penetration.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.149.2-149.2
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• 2012

세계전파통신회의 (WRC; World Radiocommunication Conference)회의는 국제전기통신연합 (ITU)에서 규정하는 국제 전파법 제개정을 위해, 3-4년 간격으로 개최되는 전파통신 관련 최고회의라고 할 수 있다. WRC-15회의는 2015년 11월 2일 - 11월 27일에 걸쳐 스위스 제네바에서 개최될 예정이며, 과학업무 관련 의제들은 다음과 같다. 즉, 7145-7235 MHz 또는 7-8 GHz 대역의 지구탐사위성(지구대우주)업무의 1순위 분배연구, 지구탐사위성업무용 연속 600MHz 대역 분배방안 연구 (8,700~10,500MHz대역 내), 우주선 근거리통신용 관련 규정 재검토, 윤초삭제와 관련된 세계협정시(UTC) 개정 또는 대처방안 연구가 있다. 그리고 모바일광대역 응용 실현을 위한 이동통신업무 추가 분배 및 IMT 추가 지정 연구, 7150-7250MHz (우주대지구), 8400-8500MHz (지구대우주)에서 고정위성업무 추가 분배연구, 나노 위성 및 피코 위성 규제 관련 연구들이 있다. 따라서 본 발표에서는 WRC-15회의의 과학업무 의제들 가운데, 국내전파망원경 운용에 영향을 미칠 수 있는 주파수 대역 및 윤초 관리 등과 관련된 주요 과학업무 의제를 소개하고 이에 대한 향후 대응책 검토를 하고자 한다.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.349-360
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• 2002

In ITU H.323 teleconference system, the RTP/RTCP protocol is offered to transfer real-time multimedia stream. Both sender and receiver hate experience in packet loss and jitter which result from network congestion over Internet. Audio quality over Internet depends on the number of lost packets and on jitter between successive packets. The goal of our study is to improve the speech quality over Internet by checking the packet loss characteristics of the network and adopting the but for control management mechanism at the receiver. We suggest a dynamic redundant audio transmission mechanism which examines the packet loss rate and uses the feedback information through RTCP.