• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.248-251
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• 2000

The ATM-PON is regarded as an effective access network because the system transmits the various user's information through the passive optical splitter in a single platform. The ranging technology is to place all ONUs at the same distance virtually in order to form ATM-PON based on the Time Division Multiplexing (TDM). In This paper, We show the steps about ranging protocol based on ITU-T G.983.1 and ranging procedure modeling. Also, We implement the simulator that considers various environments to verify the time specifications of G.983.1. By using the simulator, We find out the wasted bandwidth which influences active ONUs during the ranging procedure.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.340-345
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• 2015

The Internet traffic is forecasted to grow at a compound annual rate of 21 % from 2013 to 2018, according to surveys carried out by Cisco [1]. Network resources are significantly over-provisioned in today's networks, and it is quite common to see link utilization in the 30-40% range [2]. Additionally, the multi-media services have widely divergent bandwidth and Quality of Experience (QoE) requirements. Unfortunately, the huge transmission capacity will increase the power consumption of network equipment [3]. Applications Coordinated with Transport, Internet Protocol and Optical Networks (ACTION) [4] has been proposed to realize a multi-QoE, application-centric, and highly energy-efficient network that leverages flexible elastic optical network technologies [5-7]. This paper provides key network technologies for realizing the ACTION, which are a virtual optical slice core network and a Time Division Multiplexing (TDM)-based deterministic active optical access network.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.06a
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• pp.133-134
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• 2017

본 논문에서는 차세대 방송 표준 ATSC (Advanced Television Systems Committee) 3.0 기반 LDM (Layered Division Multiplexing) 및 스케일러블 비디오 코덱 (Scalable Video Codec) 을 활용한 지상파 방송시스템 기술을 살펴보고 그 성능을 비교 분석한다. 코어 레이어 (Core Layer)와 인핸스드 레이어 (Enhanced Layer)로 구성된 LDM 기반 PLP (Physical Layer Pipe)에, 스케일러블 비디오 코딩이 적용된 베이스 레이어 (Base Layer)와 인핸스먼트 레이어 (Enhancement Layer) 스트림을 각각 전송함으로써 하나의 RF 채널에 두 개 이상의 서비스를 전달할 경우 채널 효율을 극대화 할 수 있다. 본 논문에서는 이동 및 고정용 서비스, 즉 두 개의 서비스를 전송할 때 제안된 LDM 및 스케일러블 비디오 코덱을 사용한 기술과 TDM (Time Division Multiplexing) 및 Simulcast 를 적용한 기술과의 성능 비교를 통해 제안된 기술의 우수성을 검증하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1321-1328
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• 2009

In this paper, an electromagnetic force driving actuator (EMFA) and three-link mechanism are proposed as a driving mechanism and connection device for low voltage air circuit breaker (ACB). As the result of dynamic characteristic analysis, the actuator and link mechanism are designed from the simulation and manufactured. The magneitc field of the EMFA is analyzed using the finite element method (FEM). The dynamic characteristic analysis with calculation of the circuit equation and kinetical equation is performed by the time difference method (TDM). Also, the result of the analysis is verified through the experiment of the fabrication model. In this paper, the EMFA size is smaller than the actuator for high voltage circuit breaker. Thus, the dynamic characteristic is analyzed with end-winding inductance that is calculated by the same method which is applied on the circle type end-winding of motors. The designed model for 1600 ampere-frame ACB and the three-link mechanism for connecting contact part with actuating part are manufactured. It is confirmed that the three-link mechanism is possible for improving the circuit breaker efficiency and reducing the size of the EMFA. It is proved that the improved 2-D analysis is more accurate than established method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.730-735
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• 2003

In this paper, four different types of BSTO tunable bandpass filters with ferroelectrics are proposed. The achievement of the tunability is based on the fact that the increase in the bias voltage leads to the reduction of the effective dielectric constant. Therefore, the center frequency shifts to the higher value with the higher bias voltage. The most frequently used and well-known ferroelectrics are STO and BSTO materials where the STO is mainly used below 100K while the BSTO is used at room temperature. The proposed technology seems very useful and promising for the development of the next-generation wireless communications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.410-415
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• 2002

This paper describes the implementation of a SoC(System-on-a-Chip) and an ISDN communication terminal by the SoC in ISDN network. The SoC has been developed with the functions of 32-bit ARM7TDMI RISC core processor, network connection with S/T interface, TDM--bus interface and voice codec, user interface. And we also review the developed software structure and the ISDN service protocol procedures which are working on the SoC. And finally this paper describers a structure of an ISDN terminal equipment using the implemented SoC and terminal software.

• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.89-93
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• 2001

In recent years Fiber optic hydrophone systems have been the focus of much attention in the sonar world. For sonar arrays, a fiber optic approach offers the major benefit of passive multiplexing of large numbers of hydrophones without underwater electronics. This paper describes recent development work covering array construction, opto-electronics development, hydrohpone design and sea trials. And the development of an interferometric mult-channel fiber optic hydrophone system which uses time division multiplexing capable of driving in excess of 32 channel is described. For this, a 12 channel time division multiplexing array has been constructed, and the performance of this system is demonstrated by sea trial.

• Korea Journal of Hospital Management
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• v.5 no.1
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• pp.200-231
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• 2000

The price systems of the hospital drug services play key roles in the provision of quality services and the development of pharmacy service technologies. Under the premises, this study attempted to determine the costs of hospital drug service, to compare the costs calculated with the fees publicly fixed by the Government, and based on the results of the analysis, to propose directions for the improvement of the price systems. A Costing model for the study was developed based on the cost-fee relationship analysed of the Korean fee-for-service systems. Data on costs and workloads of the 25 hospitals were collected through survey forms designed for the costing' and analysis for the duration of 12 months of 1998. The results of the analysis show that a tremendous unbalance between cost and price levels of the drug services, and that overally the price level of the services is extremely low when compared to the costs of services. Based on these findings, this study suggests that unfairly high or low price level be corrected, and that service items newly developed and being practiced at tertiary hospitals, such as TDM and TPN consultation services, be compensated by fixing a proper level of price.

• Electronics and Telecommunications Trends
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• v.27 no.2
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• pp.89-98
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• 2012

광통신 기술의 발달과 인터넷 서비스 수요의 급격한 증가로 2000년대 초반부터 광가입자망 연구 및 상용화가 이루어졌다. 최근에는 스마트폰 등 모바일 단말의 확산과 IPTV의 수요 증대에 따른 폭발적 트래픽 증가에 대처하기 위하여 친환경, 에너지 절감형 차세대 초고속 대용량 광가입자망 기술에 대한 요구가 증대되고 있다. 차세대 광가입자망은 국내뿐 아니라 국외에서도 다양한 프로젝트를 통해 전송 거리, 분기 수 및 전송 용량을 늘리는 방향으로 연구개발이 진행되고 있으며 기존의 TDM, WDM(Wavelength Division Multiplexing) 기술뿐만 아니라 무선 통신에서 사용되던 OFDM(Orthogonal Frequency-Division Multiplexing) 등의 신호변조 기법들을 광가입망 기술에 접목하려는 시도들이 진행되고 있다. 이와 같은 광가입자망 기술들은 ITU-T, IEEE, IEC뿐만 아니라 FSAN(Full Service Access Network), BBF(Broadband Forum), MSF(Multi-service Forum) 등의 표준화 단체에서 활발히 국제표준화가 진행 중이다. 본고에서는 현재 진행되고 있는 차세대 광가입자망 기술에 대한 국내 외 기술개발 현황 및 표준화 현황을 살펴보고자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.1
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• pp.69-75
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• 2011

Firing tests have been carried out for a technology demonstration model of 75-tonf-class combustor which is to be used on the liquid rocket engine of a Korean space launch vehicle. Firing tests were done at 50% of the nominal flow rate because of incapability of the test facility and limit of the test bed strength. Through the low pressure firing tests of 75-tonf-class channel cooling thrust chamber, operability and stability at the ignition and combustion phases were confirmed. Additionally it was foreseen that the 75-tonf-class thrust chamber would satisfy the performance requirements.