• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.224-236
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• 1997

In order to control the flow of traffic in ATM networks and optimize the usage of network resources, an appropriate control mechanism is necessary to cope with congestion or prevent degradation of network performance caused by congestion. While the conventional UPC algorithm provides only unstable preventive function unrelated with the state of networks and is unable to recover congestion, the proposed adaptive UPC algorithm supervises the situation of ATM networks using the information from OAM cell. Then the monitor of the proposed adaptive UPC algorithm controls leaky rate and buffer threshold value according to QOS. Therefore, the proposed algorithm can cope with congestion as well as prevent and react sensitively to buffer delay. In proportion to the diversity of traffic and the increase of transmission rate in networks, the adaptive UPC-BT algorithm proposed in this paper can be effectively used in ATM networks with wide applications. This paper shows that the proposed algorithm efficiently uses in ATM networks with application. This paper shows that the proposed algorithm efficiently use network resources and provides QOS to users for various kinds of traffics by comparing with conventional UPC algorithms.

• Journal of Ecology and Environment
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• v.45 no.4
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• pp.305-312
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• 2021

Background: Butterflies make an important part for plant-pollinator guild. These are nectar feeder or occasionally pollen feeder and thus proboscis of the butterfly species are considered as one of the most important variable in relation to the collection of food from plants. In butterfly-plant association, nectar source is principally determined by quality of nectar, corolla length, and nectar quantity. For the butterfly, nectar uptake is determined by proboscis length because flowers with long corolla restrict butterfly species containing shorter proboscis. Empirical studies proved that butterfly species with high wing loading visit clustered flowers and species with low wing loading confined their visit to solitary or less nectar rich flowers. The present study tries to investigate the flower preference of butterfly species from Lycaenidae family having very short proboscis, lower body length, lower body weight and wing span than the most species belonging from Nymphalidae, Pieridae, Papilionidae, and Hesperiidae. Results: Butterflies with shorter proboscis cannot access nectar from deeper flower. Although they mainly visit on less deeper flower to sucking nectar, butterflies with high wing loading visits clustered flowers to fulfill their energy requirements. In this study, we demonstrated flower choice of seven butterfly species belonging to Lycanidiae family. The proboscis length maintains a positive relationship with body length and body weight. Body length maintains a positive relationship with body weight and wing span. Wing span indicate a strong positive relationship with body weight. This study proved that these seven butterfly species namely Castalius rosimon (CRN), Taracus nara (TNA), Zizinia otis (ZOT), Zizula hylax (ZHY), Jamides celeno (JCE), Chilades laius (CLA), and Psuedozizeeria maha (PMA) visit frequently in Tridax procumbens (TPR), Ocimum americanum (OAM) and Syndrella nodiflora (SNO). The species do not visit Lantana camara (LCA) and Catharanthus roseus (CRO) plants. Conclusion: The present study proved that butterfly species visits frequently in Tridax procumbens (TPR), Ocimum americanum (OAM) but less frequently in Syndrella nodiflora (SNO). So, that study determined the butterfly species helps in pollination of these herbs that in turn helps the conservation of these butterfly species.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1311-1322
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• 1997

Performance management of ATM network is urgently required because a different quality of service should be guaranteed on each connection. A lot of performance measurement data increase the burden on agent systems and on managment stations. In this paper, an effective OAM-based performance monitoring and faulty node identification technique is proposed. A proposed VP Selection Algorithm reduces management-related traffic and when the indication of hard or soft failure state is detected, failed node is identified by Fault Identification Rule.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.92-95
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• 2003

Frequency is an important operating parameter of a power system. Electric power systems sustain transient frequency swings whenever the balance between generation and load does not no longer hold. To cope with this Constraints. it requires an accurate and high speedy frequency deviation estimation technique and suitable adjustment to obtain the power system energy balance. This paper describes the design, computational aspects and implementation of an iterative technique for measuring power system. The rate change of the phase angle is used for estimation. To confirm the validity of the proposed algorithm, the simulation studies carried out on a typical 154[KV] double T/L system by using EMTP software. Some test results are presented in the paper.

• Electronics and Telecommunications Trends
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• v.21 no.6 s.102
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• pp.64-76
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• 2006

최초의 이더넷 IEEE 표준인 48비트 주소체계와 버스 토폴로지를 갖는 10Mbps 이더넷이 1985년에 승인받은 이후, 이더넷 기술은 1995년 100Mbps 이더넷, 1998년 1Gbps 이더넷, 2002년 10G 이더넷 표준 등장으로, 전송 용량을 10배씩 높이는 기술 발전이 표준으로 완성까지 시간이 오히려 짧아질 정도로 숨가쁘게 진화를 거듭하였다. 이더넷 전송 용량의 급속한 증가는 LAN과 WAN간 액세스 속도 차이를 급속하게 줄이는 결과를 가져와, 그렇지 않아도 대역폭 제한과 유연성 결여로 문제가 되던 전통적인last mile WAN 서비스를 대체하는 것을 시작으로 결국에는 pure Ethernet WAN transport 기술로 캐리어 이더넷이라는 새로운 이더넷 적용 분야가 등장하게 되었다. 이 글에서는 캐리어 이더넷 네트워크 서비스의 출현 과정과 서비스 특징을 소개하며, 캐리어 이더넷 네트워크 구조 관련 요소 기술로 이더넷의 백본 확장 기술, OAM, resilience, QoS 기술 동향을 정리하고, 마지막으로 캐리어 이더넷 개발 현황과 향후발전 전망에 대하여 살펴본다.

• Journal of the Korea Society for Simulation
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• v.8 no.4
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• pp.125-136
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• 1999

In the forthcoming public ATM/B-ISDN, the efficient resource management with pre-planned transit networking which public domain NNI signaling is essential to maintain high network utilization and to assure QoS to the multimedia service users. For this purpose the transit networks must be managed according to the bearer service capability which is defined by ATM Forum and ITU-T. In this paper, we introduce an implementation of ATM transit networking with ATM VP-XC(Virtual Path cross-connect) and US(Network Management System). The functions of ATM VP-XC and NMS have been simulated with OPNET 6.1 modules. We implemented the F4 OAM functions of ATM VP connection according to the ITU-T 1.610 recommendation. Also, the ATM VP transit networking is managed by the NMS according to the connection management architecture of the TWN(Telecommunications Management Network) /TINA ( Telecommunications Information Networking Architecture).

• Information and Communications Magazine
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• v.30 no.7
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• pp.33-40
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• 2013

OTN(Optical Transport Network) 기술은 다양한 형태의 신호 수용과 신호 다중화로 대용량 신호의 장거리 전송을 가능하게 한다. 또한 서브파장 단위의 스위칭 능력과 풍부한 OAM 기능은 고대역 트래픽 자원 관리에 적합하다. 이와 같은 필요성에 의해서 광전달망 기술은 발전에 한계에 도달한 SONET/SDH를 대체하면서 기간망에 도입되고 있는 표준 기술이다. 본고에서는 OTN 구조 및 다중화 기술에 대해 살펴보고, 광전송망에서의 대역폭 증감 기술, OTN 전송망의 신뢰성 보장을 위한 OTN 보호절체 기술, 100GE 이후의 차세대 이더넷 수용 및 고속 전송에 대비한 Beyond 100G OTN 기술, 비용 절감과 네트워크 자원의 효율적 사용을 위한 OTN 스위칭 기술에 대해 알아본다.

• ETRI Journal
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• v.19 no.3
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• pp.98-115
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• 1997

The architecture of the CDMA mobile system (CMS) is developed based on three function groups - service resource, service control, and service management groups. In this paper, the CMS architecture is discussed from the point of view of implementing these functions. The variable length packets are used for transmission. The synchronization clock signals are derived form the GPS receiver. The open loop and closed loop techniques are used for the power control. The internationally accepted signaling and network protocols are employed. The call control for the primary services in designed to provide efficient mobile telecommunication services. The softer handoff is implemented in one card. The mobile assisted handoff and the network assisted handoff are employed in the soft and hard handoffs. The authentication is based on the secret data which includes random numbers. The management functions, which include the location management, resource management, cell boundary management and OAM management, are implemented to warrant the system efficiency, maximum capacity and high reliability. The architecture ensures that the CMS is flexible and expandable to provide subscribers with economic and efficient system configuration. The dynamic power control, adaptive channel allocation. and dynamic cell boundary management are recommended for future work.

• Electronics and Telecommunications Trends
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• v.30 no.3
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• pp.95-104
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• 2015

모바일 빅뱅이라고 불리는 모바일 데이터 전송량의 폭발적인 증가로 촉발된 5G 이동통신에 대한 논의는 현재 ITU-R(International Telecommunication Union-Radio-communication)에서 5G 이동통신 네트워크 서비스 비전에 대한 직업을 진행 중이다. 5G 이동통신의 면적당 전송용량을 만족하기 위해서는 소형셀 형태로의 진화는 필연적이다. 본고에서는 5G 이동통신망 구성의 한 축을 담당할 것으로 예상되는 고정 무선링크 기술에 대한 개발동향을 소개한다. 고정 무선링크에 대한 사용 용도, 시장전망 그리고 현재 고정 무선링크 용도로 사용이 가능한 주파수 분배 현황에 대하여 살펴보고, 최근 고정 무선링크와 관련하여 시스템에 적용 중인 기술들과 새롭게 연구 중인 LOS(Light of Sight)-MIMO(Multi-Input Multi-Output), OAM(Orbital Angular Momentum) 등 관련 기술에 대한 개발동향을 소개한다.

• ETRI Journal
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• v.14 no.2
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• pp.72-90
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• 1992

SDH(Synchronous Digital Hierarchy) 에 의한 동기식 전송방식은 비동기식 전송장치의 관리특성상의 문제점을 고려하여 일원화된 망관리가 가능하도록 OSI 망관리 기법에 기본을 둔 TMN(Telecommunication Management Network) 접속기능이 CCITT 에 의해 권고되었다. 본 논문은 동기식 전송망의 관리를 위해서 필요한 TMN 과 SMN 구조, OAM 메시지 전달 프로토콜, 메시지구조에 대해 고찰하고 현재 ETRI에서 개발되고 있는 155Mb/s 급 동기식 전송장치에 직접 실장된 Agent, MIB, 그리고 OSI 7Layer 의 구현내용을 기술하였다