• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.413-414
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• 2015

SDN은 네트워크 장비의 control plane과 data plane을 분리하고, 중앙의 컨트롤러를 통해 네트워크를 제어한다. 네트워크 운영에서 monitoring은 필수적인 요소이며, SDN 환경에서의 기존의 monitoring 방법인 OpenTM은 in-band network 환경을 고려하지 않았다. 본 논문은 in-band network 환경에서 hop-count와 정확도를 고려하여 높은 정확도를 유지하면서도 네트워크 부하를 줄일 수 monitoring 방법을 제안한다.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.165-171
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• 2021

Vehicular Ad hoc Network (VANET) is an extension paradigm of moving vehicles to communicate with wireless transmission devices within a certain geographical limit without any fixed infrastructure. The vehicles have most important participation in this model is usually positioned quite dimly within the certain radio range. Fuzzy based multi-hop broadcast protocol is better than conventional message dissemination techniques in high-mobility VANETs, is proposed in this research work. Generally, in a transmission range the existing number of nodes is obstacle for rebroadcasting that can be improved by reducing number of intermediate forwarding points. The proposed protocol stresses on transmission of emergency message projection by utilization subset of surrounding nodes with consideration of three metrics: inter-vehicle distance, node density and signal strength. The proposed protocol is fuzzy MHB. The method assessment is accomplished in OMNeT++, SUMO and MATLAB environment to prove the efficiency of it.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.511-513
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• 2011

기존의 Wireless Mesh Network(WMN)에서 제안된 EFMP DSDV 기법은 우회 경로 이후의 잉여 대역폭이 좋지 않을 경우 우회하지 않았을 때보다 성능이 더 좋지 않은 경우가 발생한다. 이 같은 단점을 보완하기 위하여 본 논문에서는 우회 경로 다음 홉 간의 경로 정보인 Hop수와 잉여대역폭에 대한 정보를 획득하여 수식으로 유도된 Bypass값을 통해 각 우회경로의 비교를 제안한다.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.783-790
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• 2009

The necessity of wireless sensor networks is increasing in the recent years. So many researches are studied in wireless sensor networks. The clustering algorithm provides an effective way to prolong the lifetime of the wireless sensor networks. The one-hop routing of LEACH algorithm is an inefficient way in the energy consumption of cluster-head, because it transmits a data to the BS(Base Station) with one-hop. On the other hand, other clustering algorithms transmit data to the BS with multi-hop, because the multi-hop transmission is an effective way. But the multi-hop routing of other clustering algorithms which transmits data to BS with multi-hop have a data bottleneck state problem. The unequal clustering algorithm solved a data bottleneck state problem by increasing the routing path. Most of the unequal clustering algorithms partition the nodes into clusters of unequal size, and clusters closer to the BS have small-size the those farther away from the BS. However, the energy consumption of cluster-head in unequal clustering algorithm is more increased than other clustering algorithms. In the thesis, I propose an energy efficient unequal clustering algorithm which decreases the energy consumption of cluster-head and solves the data bottleneck state problem. The basic idea is divided a three part. First of all I provide that the election of appropriate cluster-head. Next, I offer that the decision of cluster-size which consider the distance from the BS, the energy state of node and the number of neighborhood node. Finally, I provide that the election of assistant node which the transmit function substituted for cluster-head. As a result, the energy consumption of cluster-head is minimized, and the energy consumption of total network is minimized.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1446-1459
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• 2008

In an infrastructure-based wireless network, an access point is used for all communications among mobile devices. However, when a mobile device moves into a dead Bone, a connectivity disruption between the mobile device and the access point occurs. Such connectivity disruption consequently leads to another connectivity disruption between the mobile device moving toward the dead zone and other wireless-enabled devices located within the area of the infrastructure-based wireless network. To cope with the connectivity disruption in the infrastructure-based wireless network the ad hoc network that dynamically forms a network without any preexisting communication infrastructure needs to be set up to provide seamless connections among mobile devices. In this paper, we propose the DNSQ-MAC (Dynamic Network State aware QoS-Medium Access Control) technique that meets the deadlines of MAC frames forwarded over hop-by-hop multipaths and guarantees the QoS performance of an ad hoc-based wireless network. Mobile devices incorporating the DNSQ-MAC technique are capable of adjusting to the new dynamic network status in order to enhance the QoS performance in the ad hoc-based wireless network. A case study which exploits the Qualnet simulator shows that the proposed DNSQ-MAC technique can guarantee the deadlines of MAC frames forwarded over hop-by-hop multipaths and enhance the QoS performance of various routing protocols and packet schedulers running on the network layer above the MAC layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.250-262
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• 2004

In IPv6 environment, the Internet Telephony, VoD(Video on Demand) and high capacity file exchange service will be more increased than IPv4. Therefore, the strict guarantee of QoS based on End-to-End and differentiated quality control schemes are simultaneously required. This paper proposes the flow control schemes on IPv6 network that the traffic is identified by flow and the QoS of multi-service is improved by QoS information in IPv6 hop-by-hop option header. The object of flow control includes not only non-default QoS traffic, which uses the flow label, but also best-effort or encrypted traffic. Therefore, the guarantee of real-time service is strengthened and the flow, which abuses unnecessarily the network resources, is effectively controlled. Also, this paper proposes the mapping scheme between the flow and MPLS by reflecting the minimum change of the existed network resource and the status of backbone network of ISP(Internet Service Provider). In the simulation result, It is shown that the proposed scheme is effective in the side of QoS on real-time services and utilization of backbone resources.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.114-126
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• 2011

Video streaming over wireless multi-hop networks(WMNs) contains the following challenges from channel fading and variable bandwidth of wireless channel, and it cause degradation of video streaming performance. To overcome the challenges, currently, WMNs can use Forward Error Correction (FEC) mechanism. In WMNs, traditional FEC schemes, E2E-FEC and HbH-FEC, for video streaming are applied, but it has long transmission delay, high computational complexity and inefficient usage of resource. Also, to distinguish network status in streaming path, it has limitation. In this paper, we propose monitoring-based coordination of network-adaptive hop-to-end(H2E) FEC scheme. To enable proposed scheme, we apply a centralized coordinator. The coordinator has observing overall monitoring information and coordinating H2E-FEC mechanism. Main points of H2E-FEC is distinguishing operation range as well as selecting FEC starting node and redundancy from monitored results in coordination. To verify the proposed scheme, we perform extensive experiment over the OMF(Orbit Measurement Framework) and IEEE 802.1la-based multi-hop WMN testbed, and we carry out performance improvement, 17%, from performance comparison by existing FEC scheme.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.11
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• pp.263-270
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• 2019

Vehicular cloud computing is a new emerging technology that can provide drivers with cloud services to enable various vehicular applications. A vehicular cloud is defined as a set of vehicles that share their own resources. Vehicles should collaborate with each other to construct vehicular clouds through vehicle-to-vehicle communications. Since collaborating vehicles to construct the vehicular cloud have different speeds, directions and locations respectively, the vehicular cloud is constructed in multi-hop communication range. Due to intermittent wireless connectivity and low density of vehicles with the limited resources, the construction of vehicular cloud with multi-hop communications has become challenging in vehicular environments in terms of the service success ratio, the service delay, and the transmitted packet number. Thus, we propose a multi-hop vehicular cloud construction protocol that increases the service success ratio and decreases the service delay and the transmitted packet number. The proposed protocol uses a connection time-based intermediate vehicle selection scheme to reduce the cloud failure probability of multi-hop vehicular cloud. Simulation results conducted in various environments verify that the proposed protocol achieves better performance than the existing protocol.

• Journal of Korea Entertainment Industry Association
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• v.13 no.8
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• pp.267-280
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• 2019

The hybrid phenomenon of pronunciation of K-Pop lyrics, which is the diction fusion phenomenon of lyrics, is not a strategic measure for an overseas expansion but a natural formation in the course of history of K-Pop. With the debut of Seo Tai-ji and Boys in 1992, the course of K-Pop changed and settled from ballad to dance music. After three years, the success of a hip hop dance music, 'Come Back Home', opened up a door to Korean Americans who ascertained the potential competitiveness of a hip hop music in K-Pop market. And the writer insists that such advance of Korean Americans into K-Pop market is the origin of the bilingual usage and diction fusion phenomenon of K-Pop lyrics. Therefore, this research will look into the pronunciation system of Korean and English in order to understand the bilingual pronunciation system shown in the lyrics sung by Korean American hip hop singers in the 1990s. Moreover, through Korean pronunciation system, this analysis will discover the main cause of continual acceptance and application of Korean American's broken Korean in the diction of lyrics. Last but not least, this exploration will show the correlation of English pronunciation method of Korean lyrics appeared in K-Pop and the diction of Korean lyrics used by Korean American hip hop singers in late 90s. This research will identify the primary cause of the diction fusion phenomenon in the course of history of K-Pop.

• ETRI Journal
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• v.30 no.2
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• pp.341-343
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• 2008

This letter presents an angular minimum spanning tree (AMST) algorithm for topology control in multi-hop wireless ad hoc networks. The AMST algorithm builds up an MST for every angular sector of a given degree around each node to determine optimal transmission power for connecting to its neighbors. We demonstrate that AMST preserves both local and network-wide connectivity. It also improves robustness to link failure and mitigates transmission power waste.