• Asian-Australasian Journal of Animal Sciences
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• v.16 no.9
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• pp.1261-1267
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• 2003

We have investigated whether HspBP1, a Hsp70 binding protein, could have effect on the assembly of the bovine progesterone receptor (bPR) with a chaperone complex consisting of bovine Hsp90 (bHsp90), bovine Hsp70 (bHsp70), Hop, Ydj-1, and p23. The bPR, isolated in its native conformation, loses its function to interact with progesterone hormone in the absence of this protein complex. However, in the presence of bHsp90, bHsp70, Hop, p23 and Ydj-1, its function could be restored in vitro. Our findings here indicate that the inclusion of HspBP1 to five-protein system prevented the proper assembly of progesterone receptor-chaperone complex and induce the loss of bPR ability to interact with hormone. Immunoprecipitation assays of bPR with HspBP1 show that the presence of HspBP1 did not have any effect on the assembly of Ydj-1 and bHsp70 with the progesterone receptor. However, further assembly of Hsp90, Hop and p23 was completely prevented and the function of the bPR was lost. In vitro competition and protein folding assays indicated that the binding of HspBP1 to bHsp70 prevented the ternary complex formation of bHsp70, bHsp90, and Hop. These results indicate that HspBP1 is a negative regulator of the assembly of Hsp90, Hop and Hsp70, and thus, prevent the proper maturation of unliganded bPR with chaperones assembly system.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.6 no.3
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• pp.1-7
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• 2007

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide efficient utilization in optical networks. Under several legacy schemes, a switch drops the burst with the shortest time regardless of its traversed hop count. As a result, a dropped burst that have been traversed many hops might cause increased bandwidth waste compared to one that has traversed a few hops. To improve this problem, we propose the Just Enough Time (JET) with a hop counting scheme which can reduce the wasted bandwidth by prioritizing the burst traversed many hops over others. From the simulation result, it is preyed, we show that the proposed scheme has advantages against legacy schemes in terms of the burst blocking probability and the link utilization.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.1
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• pp.7-12
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• 2010

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide an efficient utilization in optical Wireless networks. Under several legacy schemes, a switch drops the burst with a shorter time among ones regardless of its traversed hop counts. As a result, the dropped burst that have been traversed more hops might cause to waste bandwidth than the one traversed a few hops. Noting that this problem, we propose the Just Enough Time (JET) with a hop count scheme which can reduce the wasted bandwidth by prioritizing the burst traversed more hops over others. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.5-25
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• 2009

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.34-39
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• 2005

In this paper, we propose a new prioritized Optical Burst Switching (OBS) protocol based on a hop count, which can provide an efficient utilization in optical Wireless networks. Under several legacy schemes, a switch drops the burst with a shorter time among ones regardless of its traversed hop count. As a result, the dropped burst that have been traversed more hops might cause to waste bandwidth than the one traversed a few hops. Noting that this problem, we propose the Just Enough Time(JET) with a hop count scheme which can reduce the wasted bandwidth by prioritizing the burst traversed more hops over others. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the burst blocking probability and the link utilization.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.94-99
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• 2010

In this paper, we discuss a proposed two hop relay network with PB/MC-CDMA(partial block MC-CDMA) technique. The main advantages of PB/MC-CDMA system are the increased cell capacity and the high quality of performances. In the system, we employ relay scheme to focus on the coverage reduction and hotspot problem, hotspot is a location where a cluster of users are blocked or dropped for the reason of insufficient frequency resources. Frequency resource allocation scheme is put forward in a three cells system according to each problem. The simulation result shows the performance of the two hop transmission is better than the direct transmission and the proposed network can support much more users to relief hotspot effect compared to the conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6B
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• pp.350-357
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• 2007

The IEEE 802.15.3 high-rate WPAN has been developed to communicate with devices within l0m. A piconet consists of one Piconet Coordinator (PNC) and several devices. The devices associated with a parent piconet can become child PNCs in order to form child piconets. A mesh network made up of a parent piconet and several child piconets can support multi-hop communications. In this paper, we analyze the maximum level and the avaliable superframe size to make the best use of bandwidth for multi-hop communications, and compare the analysis with the simulation results in terms of time to discover devices for multi-hop communications. The average number of levels in mesh networks is shown to be about 1.9 when the number of devices increases within a fixed area. We have also shown that the maximum available superframe size is 52ms and the discovery time is approximately 155ms.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.1-11
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• 2009

In this paper, we propose a QoS routing protocol for WiMAX based wireless mesh networks. The proposed routing protocol is a proactive hop-by-hop QoS routing protocol. It can find an optimal route that satisfies QoS requirements using bandwidth and delay as QoS parameters. In this paper, we first present a network model for WIMAX based wireless mesh networks and explain why QoS routing protocol is the most appropriate for WiMAX based wireless mesh networks. Then, we propose a proactive hop-by-hop QoS routing protocol that meets QoS requirements of traffic flowing between mesh client and the gateway. The simulation results show that the proposed routing protocol outperforms QOLSR protocol in terms of end-to-end delay, packet delivery ratio and routing overhead.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.65-74
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• 2016

Ship ad-hoc network (SANET) extends the coverage of the maritime communication among ships with the reduced cost. To fulfill the growing demands of real-time services, the SANET requires an efficient clock time synchronization algorithm which has not been carefully investigated under the ad-hoc maritime environment. This is mainly because the conventional algorithms only suggest to decrease the beacon collision probability that diminishes the clock drift among the units. However, the SANET is a very large-scale network in terms of geographic scope, e.g., with 100 km coverage. The key factor to affect the synchronization performance is the signal propagation delay, which has not being carefully considered in the existing algorithms. Therefore, it requires a robust multi-hop synchronization algorithm to support the communication among hundreds of the ships under the maritime environment. The proposed algorithm has to face and overcome several challenges, i.e., physical clock, e.g., coordinated universal time (UTC)/global positioning system (GPS) unavailable due to the atrocious weather, network link stability, and large propagation delay in the SANET. In this paper, we propose a logical clock synchronization algorithm with multi-hop function for the SANET, namely multi-hop clock synchronization for SANET (MCSS). It works in an ad-hoc manner in case of no UTC/GPS being available, and the multi-hop function makes sure the link stability of the network. For the proposed MCSS, the synchronization time reference nodes (STRNs) are efficiently selected by considering the propagation delay, and the beacon collision can be decreased by the combination of adaptive timing synchronization procedure (ATSP) with the proposed STRN selection procedure. Based on the simulation results, we finalize the multi-hop frame structure of the SANET by considering the clock synchronization, where the physical layer parameters are contrived to meet the requirements of target applications.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.1
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• pp.39-45
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• 2012

In this paper, a distributed 2-hop routing algorithm is proposed. The main purpose of the proposed algorithm is to reduce the overall power consumption of each sensor node so that the lifetime of WSN(wireless sensor network) is prolonged. At the beginning of each round, the base station transmits a synchronization signal that contains information on the priority table that is used to decide whether each sensor node is elected as a cluster head or not. The priority table is constructed so that sensor nodes closer to half energy distance from the base station get the higher priority. 2-hop routing is done as follows. Cluster heads inside half energy distance from the base station communicate with the base station directly. Those outside half energy distance have to decide whether they choose 2-hop routing or 1-hop routing. To do this, each cluster head outside half energy distance calculates the energy consumption needed to communicate with the base station via 1-level cluster head or directly. If less energy is needed when passing through the 1-level cluster head, 2-hop routing is chosen and if not, 1-hop routing is chosen. After routing is done each sensor nodes start sensing data.