• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.251-254
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• 2011

본 논문에서는 예약주소를 사용한 HMIPv6로 각 통신 노드에 따른 그룹 군집화와 MIH 패킷의 Service Specific TLVs의 변형을 통해 기존의 핸드오버에서 좀 더 가볍고 빠른 Searching과 효율적인 인증을 이룰 수 있도록 하였다. 군집(Aggregate) 세션 단위로 자원예약을 하는 경우 종단간 SID(Session ID)와는 별도로 군집 SID를 사용하는데 MIH의 Service Specific TLVs를 통해 터널링을 이루고 변형된 Service Specific 공간을 통한 효율적인 핸드오버를 지원한다.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.91-96
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• 2000

차세대 무선 통신 서비스의 응용은 다양한 형태로 발전하고 있다. 그 중에서 응급상황이나 학내망 같이 특수한 경우에 제공될 수 있는 시나리오로 다중 홉(Multi-hop) 다중 링크(Multi-link) ad-hoc 망을 들 수 있다. Ad-hoc망은 한정된 자원 문제와 변화가 심한 링크 용량문제가 있으며, 다중 홉상의 노드가 이동함으로 토폴로지의 동적 변화문제도 발생한다. 이러한 망의 노드는 송·수신단 역할을 할 뿐만 아니라 패킷을 전달하는 중간 노드의 역할도 하기 때문에 파워의 절약 매카니즘이 절실히 필요하게 된다. 본 논문은 PAMAS에 기반하여, 별도의 제어 채널에 버퍼를 두어 송·수신자 주소와 전송할 데이터의 크기의 정보를 버퍼에 기록하여 예약하고 제어 채널에서 데이터 채널의 파워를 제어할 수도 있으므로 데이터 전송에서 충돌을 예방하고 효율적으로 파워를 절약할 수 있다. 데이터 전송 발생율을 바꿔가며 시뮬레이션 결과 일반적인 방법을 사용한 노드들보다 훨씬 좋은 파워 절약을 이루고 있음을 알 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.121-123
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• 2014

클라우드 브로커는 대규모의 데이터센터를 거느린 클라우드 서비스 제공자와 그로부터 제공되는 자원을 이용하여 원하는 작업을 실행하는 클라우드 이용자 사이를 중개하여 제공자 측에는 보다 많은 이용자들이 서비스를 이용하는 데 용이하도록 하여 수익을 증대시키고, 이용자 측에는 정해진 예산 내에서 서비스 협정(Service Level Agreement, SLA)를 보장하여 원하는 작업을 실행하도록 하는 역할을 수행하여 스스로의 이익을 창출한다. 본 논문에서는 클라우드 브로커의 이러한 서비스 차익거래를 위해 필요한 VM 풀의 운영에 있어 효과적인 VM 예약 기법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1364-1367
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• 2007

오버레이 멀티캐스트는 기존의 IP 멀티캐스트와 달리 Infrastructure의 도움 없이 멀티캐스트 기능을 수행하지만 갑작스런 노드의 이탈이나 장애 발생 시 트리의 복구가 필요하다. 본 논문에서는 이를 위해 각 노드의 Out-degree 자원을 미리 예약하여 트리 복구 시 예약된 노드에게 서비스를 요청하는 방안을 제시한다. 제시된 방안은 백업 노드로 인해 신속한 트리의 복구가 가능하다. 시뮬레이션을 통해 제시한 방안이 기존의 방안에 비해 보다 작은 복구 시간을 필요로 하며 부모 노드의 이탈로 인해 많은 수의 노드가 영향을 받는 상황에서 더욱 효과적으로 동작함을 보여주고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.514-524
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• 2005

In optical burst switching(OBS) networks, the ingress edge router assembles packets in the same class queue into the appropriate size of burst. A burst control packet(BCP) is generated for channel reservation of corresponding data burst and sent earlier than the corresponding data burst with an offset time. Offset time is determined considering the number of hops from source to destination and the required quality of service(QoS). After offset time, the burst data is passed through tile pre-configured optical switches without any O/E/O conversion. But a failure in OBS networks may lead to the loss of bursts until the ingress nodes receive the failure indication signal. This results in a significant degradation in QoS. Therefore, in this paper, we propose a fault-tolerant node architecture based on sub-carrier multiplexing to reduce the effects of failure in OBS networks. The Performance of the proposed fault-tolerant node architecture exhibits considerable improvement as compared with the previous ones.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.65-76
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• 2002

QoS routing is a routing technique for finding feasible path that satisfies QoS requirements required by application programs. Since QoS routing determines such paths in terms of dynamic network state, it satisfies the requirement of applications and increases the utilization of the network. The overhead is, however, generated by routers to exchange the information of the dynamic state of network. In order to reduce this protocol overhead, a timer based update mechanism is proposed in which router checks the change of the network status periodically and network state information is exchanged if the change is greater than a certain value. Using large update period makes, though, routing performance irresponsive to the parameters which determine the update of the network state of the router. In addition to this, large update period may result in inaccurate network state information at routers and cause resource reservation failure. The resource reservation failure generates additional overhead to cancel the resource reservation of the part of the path. In this paper, we propose mechanisms enhancing the existing network state update policy with respect to these two problems. Performance of the proposed schemes are evaluated through a course of simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1346-1356
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• 2011

Transportation has been playing important role in our society by providing for people, freight, and information. However, it cuts its own throat by causing car accidents, traffic congestion, and air pollution. The main cause of these problems is a noticeable growth in the number of vehicles. The easiest way to mitigate these problems is to build new road infrastructures unless resources such as time, money, and space are limited. Therefore, there is a need to manage the existing road infrastructures effectively and safely. In this paper, we propose a road reservation scheme that provides fast and safe response for emergency vehicles using ubiquitous sensor network. Our idea is to allow emergency vehicle to reserve a road on a freeway for arriving to the scene of the accident quickly and safely. We evaluate the performance by three reservation method (No, Hop, and Full) to show that emergency vehicles such as ambulances, fire trucks, or police cars can rapidly and safely reach their destination. Simulation results show that the average speed of road reservation is about 1.09 ~ 1.20 times faster than that of non-reservation at various flow rates. However, road reservation should consider the speed of the emergency vehicle and the road density of the emergency vehicle processing direction, as a result of Hop Reservation and Full Reservation performance comparison analysis. We confirm that road reservation can guarantee safe driving of emergency vehicles without reducing their speed and help to mitigate traffic congestion.

• Korean Journal of Environment and Ecology
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• v.35 no.2
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• pp.181-192
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• 2021

This study surveyed visitors' perceptions of Mudeungsan National Park's Seoseokdae Trail Section (STS) on the visitor reservation system (VRS). Data were collected from 248 visitors to STS selected through convenient sampling in May 2019. The majority (86.9%) of the respondents rated their overall experience in STS as either "no problem at all" or "little problem". Moreover, 43.0% of the respondents were aware of the VRS. The most popular information source for VRS was the Internet (49.7%), followed by other people (18.4%) and broadcasting media, e.g., TV (17.7%). While 69.9% of the respondents thought that implementation of VRS would be effective in improving managerial conditions of the STS, respondents perceived that "cumbersome reservation procedures" (79.3%) of the VRS operation was the most important problem, followed by "unfairness associated with Internet familiarity gap" (78.7%) and "deprivation of the opportunities to visit freely" (76.3%). The support for VRS implementation was higher among higher-aged, married, higher-educated, more frequent STS visitors, Gwangju residents, and solo visitors than the other groups. The "knowledge level about VRS" and "the awareness level about potential problems associated with VRS operation" negatively influenced the support for the implementation of VRS, while "the perceived managerial effectiveness of VRS" positively influenced it.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.121-127
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• 2003

In this paper, we propose a load balancing QoS routing on a targe scale network. We use the scheme in which it calculates the cost of resources with a precomputation and then selects a path among multiple paths based on the calculated cost for each resources. We also use the QoS routing scheme for the transit and the intra-traffic on a large scale domain-based network. For a domain in networks, this routing scheme precomputes K multiple paths between all pairs made up with each ingress and egress border routers along with the consideration of a load balancing, and then picks up paths having the high probability on the Path selection. This routing scheme can be applied for the transit traffic and the intra traffic and combines the Inter-domain and intra-domain routings seamlessly and put a high priority on the transit traffic Thus, these schemes make Possible both the global use of network resources and the load balancing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9B
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• pp.1272-1280
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• 2010

WFQ (Weighted Fair Queuing) provides not only fairness among traffic flows in using bandwidth but also guarantees the Quality of Service (QoS) that individual flow requires, which is why it has been applied to the resource reservation protocol (RSVP)-capable router. The RSVP allocates an enough resource to satisfy both the rate and end-to-end delay requirements of the flow in condition of no packet loss, and the WFQ guarantees those QoS requirements with the allocated resource. In a practice, however, most QoS-guaranteed services, specially the Voice of IP, allow a few percent of packet loss, so it is strongly desired that the RSVP and WFQ make the best use of this allowable packet loss. This paper enhances the WFQ to allow packet loss and investigates its performance. The performance evaluation showed that allowing the packet loss of 0.4% can improve the flow admission capability by around 40 percent.