• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2149-2152
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• 2005

가속기 연구소에서 500kV 고전압 다중채널 다중갭(MGMC) 스위치를 개발하였다. 이 다중 채널 다중 갭 스위치는 개스를 채우는 방식으로 자발 방전전압을 증가 시킬 수 있는 10단의 갭으로 구성이 되어 있다. 멀티갭 스위치의 구조는 스위치의 자체 인덕턴스를 증가시키는 결과를 가져온다. 따라서 이러한 문제점을 해결하기 위하여 다중채널을 사용하여 인덕턴스를 줄이는 스위치로 구조를 설계하였다. 제작된 스위치는 500kV의 Marx generator를 사용하여 시험을 하였다. 본 논문에서는 개발된 스위치 선계 및 스위치의 특성에 대하여 알아보고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.569-580
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• 2003

One of the important advantages of multichannel switches is the incorporation of inherent fault tolerance into the switching fabric. For example, if a link which belongs to the multichannel group fails, the remaining links can assume responsibility for some of the traffic on the failed link. On the other hand, if faults occur in the switching elements, it can lead to erroneous routing and sequencing in the multichannel switch. We investigate several fault localization algorithms in multichannel crossbar ATM switches with a view to early fault recovery, The optimal algorithm gives the best performance in terms of time to localization but is computationally complex which makes it difficult to implement. We develop an on-line algorithm which is computationally mote efficient than the optimal algorithm. We evaluate its performance through simulation. The simulation results show that performance of the on line algorithm is only slightly sub-optimal for both random and bursty traffic. Finally a fault recovery algorithm is described which utilizes the information provided by the fault localization algorithm.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.83-96
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• 2005

The multichannel switch is an architecture widely used for ATM (Asynchronous Transfer Mode). It is known that the fault tolerant characteristic can be incorporated into the multichannel crossbar switching fabric. For example, if a link belonging to a multichannel group fails, the remaining links can assume responsibility for some of the traffic on the failed link. On the other hand, if a fault occurs in a switching element, it can lead to erroneous routing and sequencing in the multichannel switch. We investigate several fault localization algorithm in multichannel crossbar ATM switches with a view to early fault recovery. The optimal algorithm gives the best performance in terms of time to localization but it is computationally complex which makes it difficult to implement. We develop an on-line algorithm which is computationally more efficient than the optimal one. We evaluate its performance through simulation. The simulation results show that the Performance of the on-line algorithm is only slightly sub-optimal for both random and bursty traffic. There are cases where the proposed on-line algorithm cannot pinpoint down to a single fault. We enumerate those cases and investigate the causes. Finally, a fault recovery algorithm is described which utilizes the information provided by the fault localization algorithm The fault recovery algorithm providesadditionalrowsandcolumnstoallowcellstodetourthefaultyelement.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.7
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• pp.394-400
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• 2002

Networks of Workstations(NOWs), that has features of flexibility and scalability, recently has emerged as an inexpensive alternative to massively parallel multicomputers. However it is not easier to perform deadlock-free multicast than regular topologies like mash or hypercube. Single phase differential multicast(SPDM) is a modified multicast algorithm with less burden of the root node. By applying quality of serviece(QoS), a specific node can have differentiated service and artificial change of message flow pattern is also available. As the results of performance evaluation experiments, SPDM has lower latency and lower packet concentration rate of the root node than the case of SPAM, and has ability to control network load distribution among switch nodes by controlling the assignment rate among nodes.

• Journal of Korea Multimedia Society
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• v.2 no.2
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• pp.184-194
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• 1999

We present a new algorithm to minimize channel contention while sending multiple messages from multiple source to overlapped destination set on Multistage Interconnection Network (MIN) which supports wormhole routed turnaround routing. The multicast tree of the U-MIN(Unicast MIN) algorithm is useful in performing messages from one source to multiple destination but gives rise to a serious channel connection in performing multiple multicast because it has been designed for only single multicast. For multiple multicast communication on MIN, we address how to implement multiple multicast services efficiently. And a SPU-MIN(Source Partitioned Unicast MIN) algorithm is proposed and shown to be superior than the U-MIN algorithm for multiple multicast. The turnaround routing algorithm based on wormhole routing technique is employed as a message sending method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.744-749
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• 2016

This paper presents the design of a computer-generated hologram for beam control of an LCOS-based wavelength selective switch, which is the core technology for next-generation ROADM. By introducing a computer-generated hologram instead of general grating patterns to control the LCOS device, we contribute to building a more efficient wavelength selective switch. With the use of phase modulation properties of LCOS devices, we designed the hologram for five-port output and a 40-channel wavelength selective switch. We applied a multi-level phase modulation technique with the Gerchberg-Saxton algorithm to produce the hologram, which is easily scalable to any different type of wavelength selective switch. With an experimental setup, we verified the usability of the hologram designed for five-port output. We also suggest a hologram design technique for beam control of a 40-channel wavelength selective switch.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1827-1832
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• 2014

In this thesis, we use one by one each of the analog switch and a high-speed DAC instead of the DAC that two or more are used in transmitting and receiving antennas multiple systems, maintaining the advantages of the existing method, reducing design costs, physical to provide a method that can reduce the data converters from MIMO system can improve the economic efficiency and the size reduction of a basis.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.165-166
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• 2014

기존 LED(Light Emitting Diode) 전류 제어용 SSPR(Secondary Side Post Regulator) 스위치를 갖는 구조의 다중출력 컨버터는 LED 정 전류 제어를 위한 별도의 부스트 컨버터 없이 전류제어가 가능하여 원가 및 부피 저감과 효율이 상승하는 장점이 있다. 하지만, 주 출력단(Master)의 피드백을 받아 1차 측 메인 스위치를 제어하게 되어 제어 회로가 복잡하고 주 출력단 부하 변동에 의해 부 출력단(Slave)의 크로스-레귤레이션(Cross-Regulation) 특성이 좋지 않은 단점이 있다. 따라서, 본 논문에서는 기존 SSPR 스위치의 장점을 갖고 주 출력 단의 부하 변동에도 부 출력단의 크로스-레귤레이션 특성이 좋은 새로운 직렬 공진형 LED 구동회로를 제안한다. 최종적으로 제안 회로를 4채널 LED 구동회로에 적용하여 그 실험결과를 바탕으로 제안 회로의 타당성을 검증하였다.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.157-165
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• 2006

This paper proposes a new output-buffered multicast ATM switch with tandem crosspoints switching fabric, named the MTCOS(Multicast Tandem Crosspoint Output-buffered Switch). The MTCOS consists of multiple simple crosspoint switch fabrics, named TCSF(Tandem Crosspoint Switch Fabric) , and concentrated output buffers for efficient multicasting. The TCSF resolves the cell delay deviation problem which the self-routing crossbar switches inherently have. Further, it offers multiple concurrent pathes from one input to multiple output ports. It also provides multi-channel switching by easy software configuration and has several desirable characteristics such as scalability, high Performance, and modularity. A shared traffic concentration and output queuing strategies of the MTCOS results in lower cell loss as well as lower cell delay time over a wide range of multicast traffic. Furthermore, it has lower hardware complexity than that of the SCOQ and Knockout multicast switch to achieve the same Knockout concentration rate as the conventional switches. It is shown that the proposed switch can be easily applied to design high performance for any multicast traffic by analytic analysis and computer simulation.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.258-259
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• 2002

광회선 분배 시스템(OXC)은 전광통신망(Optical Transport Network)에서 광신호 간 연결을 원격으로 설정해 줄 수 있는 노드(Optical Network Element)이다. OXC는 다수의 입력/출력 링크를 가지며 하나의 입력/출력 링크에는 다수의 파장 다중된 광신호 채널이 존재한다. OXC는 하나의 입력 링크를 통하여 입력되는 다수의 파장 채널을 서로 다른 출력 링크로 연결해 주거나, 다수의 입력 링크로부터 입력되는 파장채널을 하나의 출력 링크로 연곁해 줄 수 있는 optical grooming 기능을 수행한다. 또한 자국에서 광신호를 Add/Drop할 수 있는 기능을 가질 수 있다. (중략)