• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.223-229
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• 2017

This paper analyzes the effect of a dual-metal-gate structure on the electrical characteristics of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors. These structures have two gate metals of different work function values (${\Phi}$), with the metal of higher ${\Phi}$ in the source-side gate, and the metal of lower ${\Phi}$ in the drain-side gate. As a result of the different ${\Phi}$ values of the gate metals in this structure, both the electric field and electron velocity in the channel become better distributed. For this reason, the transconductance, current collapse phenomenon, breakdown voltage, and radio frequency characteristics are improved. In this work, the devices were designed and analyzed using a 2D technology computer-aided design simulation tool.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제19권4호
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• pp.1001-1008
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• 2015

Mobile Ad hoc Network(MANET) consists of a node that has mobility. In MANET, the node has routing, the node builds a network of their own, no dependent infrastructure. Topology are exchanged due to node mobility in MANET. For reducing the change of topology, hierarchical network algorithm has been investigated. In hierarchical network, cluster member node communicates through cluster head node. When the load-balancing of cluster head node is exceed, assigned cluster member node can't communicate with base station. To solve this problem, we proposed Load Tolerance algorithm. The proposed algorithm, when cluster member node can't send a message by cluster head node that exceed load-balancing, then the cluster member node sends a message by selected load tolerance node. Through a simulation, the proposed algorithm improves packet delivery ratio in cluster routing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.377-380
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• 2010

MANET(Mobile Ad-hoc Network) has been proposed as a infrastructure-less network using distributed algorithm for remote environment monitoring and control. The mobility of MANET would make the topology change frequently compared with a static network and a node is resource-constrained. Hence, to improve the routing protocol in MANET, energy efficient routing protocol is required as well as considering the mobility would be needed. In this paper, we extend RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol) structure by a modifying the level of cluster. We call this network protocol CACH-RODMRP. Our contribution consists estimating the optimal level of clustering depth with considering node position and reducing the network residual energy. The simulation results of proposal algorithm show that the energy is significantly reduced compared with the previous clustering based routing algorithm for the MANET.

• The Journal of the Korea Contents Association
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• 제11권9호
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• pp.63-75
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• 2011

A number of process algebras have been proposed to develop distributed mobile real-time systems: pi-Calculus, Mobile Ambients Calculus, Bigraph, etc. However, as the systems get large and complex, the algebras become less suitable for understanding the interactions and mobility of the processes of the systems due to the size and complexity. Therefore it is necessary to handle the size and complexity for systematic understanding of the systems. This paper handles the size and complexity with a method of abstraction on sequences of interactions and movements of processes in the systems, which can be further organized in the form of hierarchically structured lattices, namely, Prism. The theoretical principle of the abstraction is based on a new concept of Behavior Ontology, which is extended from Active ontology. Prism allows the systems to be analyzed in the perspective of the lattices in Prism, which are characterized by the hierarchically organized behavioral properties of the developing systems, for systematic understanding the systems. In this way, the complexity of the interactions and the movements can be handled systematically in the semantically and hierarchically organized structure of the behavior.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제44권10호
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• pp.191-200
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• 2007

As the IEEE 802.11 WLAN has widely installed as a high-speed wireless network information infrastructure, there has been growing interest in both security and mobility of mobile terminals. However, for the case of mobile terminal employing IEEE 802.11i security standard, it is known that the user authentication procedure of IEEE 802.1x for stronger security enforcement may, due to its large delay, not be suitable for real-time multimedia communication. In this paper, we have proposed fast authentication method to resolve the above authentication delay problem, and verifies its performance via simulation analysis. Mobile terminals can get AP information reliably, and selectively execute authentication in advance during handover, which results in fast user authentication. In addition, by effectively managing the authentication information in mobile terminal, which are distributed in advance for pre-authentication, the problem of long-time revelation of authentication information has been solved.

• KIPS Transactions on Computer and Communication Systems
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• 제2권7호
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• pp.293-302
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• 2013

Home network providers have many worries about providing home network services with an expandable, reliable, flexible and low-cost structure according to the expanding market environment. The existing client-server system has various problems such as complexity and high costs in providing home network services. In this paper we propose the P2P-SIP structure. P2P communication terminal supporting access of distributed resources provides functions which the existing SIP-based network devices have. Because diverse terminals in a home network access through networks, also, partitioning network domains with home gateways to manage, and applying the network-based PMIPv6(Proxy Mobile IPv6) technology considering mobility of terminals would help to have a more efficient home network structure. Especially, the proposed P2P-SIP structure proves itself as a very efficient structure to have an outstanding expandability among different home networks in a region, and to reduce maintenance costs.

• Journal of Internet Computing and Services
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• 제8권2호
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• pp.1-13
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• 2007

GPS/GIS and RFID technologies have been changing the paradigm af our society toward ubiquitous era. Especially, geographically distributed mobile agents with transporting objects need to be automatically recognizable and traceable under certain conditions. To do this, fundamental theories and technologies are required to specify and verify spatial and temporal behaviors of agents on geographical space. This paper presents a new formal method, called Calculus of Real-Time Distribution, Mobility, and Interaction (CaRDMI), for this purpose. For specification, CaRDMI defines a map, mobile agents with transporting objects. The movement of on agent is represented by a path on the map, consisting of a list of nodes and a list of edges with spatial and temporal constraints. Interactive constraints among agents are represented by synchronization modes on objects at nodes. These constraints are distinguishable features of CaRDMI from other methods. Especially, many-to-many timed synchronization constraints are noticeable. For verification, CaRDMI presents the spatial, temporal and interactive deduction rules and the spatial and temporal equivalence relations.

• Molecules and Cells
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• 제22권1호
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• pp.97-103
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• 2006

Phosphoinositides are critical regulators of ion channel and transporter activity. There are multiple isomers of biologically active phosphoinositides in the plasma membrane and the different lipid species are non-randomly distributed. However, the mechanism by which cells impose selectivity and directionality on lipid movements and so generate a non-random lipid distribution remains unclear. In the present study we investigated which structural elements of phosphoinositides are responsible for their subcellular location and movement. We incubated phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PI(4)P) and phosphatidylinositol 4,5-bisphosphate ($PI(4,5)P_2$) with short or long acyl chains in CHO and HEK cells. We show that phosphate number and acyl chain length determine cellular location and translocation movement. In CHO cells, $PI(4,5)P_2$ with a long acyl chain was released into the cytosol easily because of a low partition coefficient whereas long chain PI was released more slowly because of a high partition coefficient. In HEK cells, the cellular location and translocation movement of PI were similar to those of PI in CHO cells, whereas those of $PI(4,5)P_2$ were different; some mechanism restricted the translocation movement of $PI(4,5)P_2$, and this is in good agreement with the extremely low lateral diffusion of $PI(4,5)P_2$. In contrast to the dependence on the number of phosphates of the phospholipid head group of long acyl chain analogs, short acyl chain phospholipids easily undergo translocation movement regardless of cell type and number of phosphates in the lipid headgroup.

• 전자공학회논문지 IE
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• 제44권1호
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• pp.20-26
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• 2007

Most researches on the mobile ad hoc network (MANET) have been focused on routing protocols, but for the real service provision DNS(Domain Name System) has to be supported first. Due to the inherent characteristics of the mobile ad hoc network, the DNS of the wired network is assumed to be not good for the MANET environment. The approach of distributed DNSs can easily adapt to the node mobility, but incurs the name conflict resolution overhead. On the other hand, the centralized approach performs the name resolution based on the unicast communication without causing the name conflict resolution overhead. The most important issue of the centralized approach is to provide the seamless name resolution service under server mobility. Therefore, in this paper, we propose a new centralized DNS, Manet DNS, which works efficiently on name allocation and management and solves the network merging and partitioning problem as well as providing the seamless name resolution service.

• Korean Journal of Agricultural Science
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• 제43권3호
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• pp.353-359
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• 2016

Soil organic carbon (SOC) retention has gradually gotten attention due to the need for mitigation of increased atmospheric carbon dioxide and the simultaneous increase in crop productivity. We estimated the statistical maximum value of soil organic carbon (SOC) fixed by clay content using the Korean detailed soil map database. Clay content is a major factor determining SOC of subsoil because it influences the vertical mobility and adsorption capacity of dissolved organic matter. We selected 1,912 soil data of B and C horizons from 13 soil series, Sangju, Jigog, Jungdong, Bonryang, Anryong, Banho, Baegsan, Daegog, Yeongog, Bugog, Weongog, Gopyeong, and Bancheon, mainly distributed in Korean upland. The ranges of SOC and clay content were $0-40g\;kg^{-1}$ and 0 - 60%, respectively. Soils having more than 25% clay content had much lower SOC in subsoil than topsoil, probably due to low vertical mobility of dissolved organic carbon. The statistical analysis of SOC storage potential of upland subsoil, performed using 90%, 95%, and 99% maximum values in cumulative SOC frequency distribution in a range of clay content, revealed that these results could be applicable to soils with 1% - 25% of clay content. The 90% SOC maximum values, closest to the inflection point, at 5%, 10%, 15%, and 25% of clay contents were $7g\;kg^{-1}$, $10g\;kg^{-1}$, $12g\;kg^{-1}$, and $13g\;kg^{-1}$, respectively. We expect that the statistical analysis of SOC maximum values for different clay contents could contribute to quantifying the soil carbon sink capacity of Korean upland soils.