• Title/Summary/Keyword: Connectivity & Transfer

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Synthesis of Crosslinked Polystyrene-b-Poly(hydroxyethyl methacrylate)-b-Poly(styrene sulfonic acid) Triblock Copolymer for Electrolyte Membranes

  • Lee, Do-Kyoung;Park, Jung-Tae;Roh, Dong-Kyu;Min, Byoung-Ryul;Kim, Jong-Hak
    • Macromolecular Research
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    • v.17 no.5
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    • pp.325-331
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    • 2009
  • The synthesis and the characterization of crosslinked ABC triblock copolymer, i.e. polystyrene-b-poly (hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid), (PS-b-PHEMA-b-PSSA) is reported. PS-b-PHEMA-b-PSSA triblock copolymer at 20:10:70 wt% was sequentially synthesized via atom transfer radical polymerization (ATRP). The middle block was crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA, as demonstrated by FTIR spectroscopy. As increasing amounts of SA, ion exchange capacity (IEC) continuously increased from 2.13 to 2.82 meq/g but water uptake decreased from 181.8 to 82.7%, resulting from the competitive effect between crosslinked structure and the increasing concentration of sulfonic acid group. A maximum proton conductivity of crosslinked triblock copolymer membrane at room temperature reached up to 0.198 S/cm at 3.8 w% of SA, which was more than two-fold higher than that of Nafion 117(0.08 S/cm). Transmission electron microscopy (TEM) analysis clearly showed that the PS-b-PHEMA-b-PSSA triblock copolymer is microphase-separated with a nanometer range and well developed to provide the connectivity of ionic PSSA domains. The membranes exhibited the good thermal properties up to $250^{\circ}C$ presumably resulting from the microphase-separated and crosslinked structure of the membranes, as revealed by thermal gravimetric analysis (TGA).

Location Analysis for Relocation of Gyeongsangbuk-do Agricultural Research & Extension Services (경상북도 농업기술원 이전을 위한 입지여건 분석)

  • Kim, Won-Jeong;Kwon, O-Sung;Jang, Kyung-Su;Yeo, Jun-Ho
    • Current Research on Agriculture and Life Sciences
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    • v.33 no.1
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    • pp.19-24
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    • 2015
  • Due to various environmental changes, the current location of the Gyeongsangbuk-do Agricultural Research & Extension Services needs to be changed to provide an appropriate environment and ecosystem for agricultural research and the efficient provision of public services. Accordingly, this study proposes a standard for selecting the new location. First, the location theory for the transfer of public facilities is investigated, and candidate filtration methods considered for the location selection. The candidate filtration methods include a component inspection, branch shape analysis, and mixed analysis. This study uses a component inspection, where the component criteria include the economic feasibility and ease of development, accessibility and convenience, agricultural conditions, soil conditions, connectivity, fairness, and human resource-richness of the region.

A Routing Protocol for Assuring Scalability and Energy Efficiency of Wireless Sensor Network (WSN의 확장성과 에너지 효율성을 보장하는 라우팅 프로토콜)

  • Jeong, Yoon-Su;Kim, Yong-Tae;Park, Gil-Cheol;Lee, Sang-Ho
    • Journal of the Korea Society of Computer and Information
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    • v.13 no.4
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    • pp.105-113
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    • 2008
  • While the wireless sensor network has a strong point which does not have effect on whole activities of network even though neighboring sensor nods fail activities of some sensor nod or make some functions disappear by the characteristic of similar information detection, it has problems which is slowing down of wireless medium, transfer character with severe error, limited power supply, the impossibility of change by optional arrangement of sensor nods etc. This paper proposes PRML techniques which performs the fittest course searching process to reduce power consumption of entire nods while guarantees the scalability of network organizing sensor nods hierarchically. The proposed technique can scatter the load of cluster head by considering the connectivity with surplus energy of nod and reduce the frequency of communication among the nods. As a result of the analysis in comparison with LEACH-C and HEED technique, PRML technique get efficiency of average 6.4% in energy consuming respect of cluster head, efficiency of average 8% in entire energy consuming respect, and more efficiency of average 7.5% in other energy consuming distribution of network scalability than LEACH-C and HEED technique.

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Design and Implementation of IoT Middleware Using Data Refinement Scheme based on IETF CoAP (IETF CoAP 기반의 데이터 정제 기법을 이용한 IoT 미들웨어 설계 및 구현)

  • Wang, Jian;SaKong, June;Kwak, Ho-Young;Kim, DoHyun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.6
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    • pp.123-128
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    • 2015
  • Recently, a communication protocol for connectivity between various sensors and actuators is issue the key technology in IoT(Internet of Things). IETF(Internet Engineering Task Force) CoAP(Constrained Application Protocol) protocol supports the communication between things like sensors and actuator nodes in a limited environment. Smart-phone will work for the data processing of the sensors and the management of IoT nodes at the next generation communication environment. In this paper, we design the connection for smart-phone and IoT node based using IETF CoAP protocol, and implement the middleware with the proposed data refinement on smart-phone. The middleware detects and eliminates a error data and duplicated data using the proposed data refinement. The proposed data refinement scheme supports to transfer a reliability information in the constrained environment.

Proton Conducting Crosslinked Membranes by Polymer Blending of Triblock Copolymer and Poly(vinyl alcohol)

  • Lee, Do-Kyoung;Park, Jung-Tae;Choi, Jin-Kyu;Roh, Dong-Kyu;Lee, Jung-Hyun;Shul, Yong-Gun;Kim, Jong-Hak
    • Macromolecular Research
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    • v.16 no.6
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    • pp.549-554
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    • 2008
  • Proton conducting crosslinked membranes were prepared using polymer blends of polystyrene-b-poly(hydroxyethyl acrylate)-b-poly(styrene sulfonic acid) (PS-b-PHEA-b-PSSA) and poly(vinyl alcohol) (PVA). PS-b-PHEA-b-PSSA triblock copolymer at 28:21:51 wt% was synthesized sequentially using atom transfer radical polymerization (ATRP). FT-IR spectroscopy showed that after thermal ($120^{\circ}C$, 2 h) and chemical (sulfosuccinic acid, SA) treatments of the membranes, the middle PHEA block of the triblock copolymer was crosslinked with PVA through an esterification reaction between the -OH group of the membrane and the -COOH group of SA. The ion exchange capacity (IEC) decreased from 1.56 to 0.61 meq/g with increasing amount of PVA. Therefore, the proton conductivity at room temperature decreased from 0.044 to 0.018 S/cm. However, the introduction of PVA resulted in a decrease in water uptake from 87.0 to 44.3%, providing good mechanical properties applicable to the membrane electrode assembly (MEA) of fuel cells. Transmission electron microscopy (TEM) showed that the membrane was microphase-separated with a nanometer range with good connectivity of the $SO_3H$ ionic aggregates. The power density of a single $H_2/O_2$ fuel cell system using the membrane with 50 wt% PVA was $230\;mW/cm^2$ at $70^{\circ}C$ with a relative humidity of 100%. Thermogravimetric analysis (TGA) also showed a decrease in the thermal stability of the membranes with increasing PVA concentration.

3GPP Standardization Activity for Small Cell Enhancement (3GPP 소형셀 향상 표준화 기술 동향)

  • Baek, SeungKwon;Chang, SungCheol
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.628-631
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    • 2014
  • Recently, the proliferation of new applications, e.g., mobile TV, Internet gaming, large file transfer, and the various of user terminals, e.g., smart phones and notebooks, has dramatically increased user traffic and network load. In order to meet this traffic growth, vendors and cellular operators are working on the development of new technologies and cellular standards. Within them, small cell deployment has been heralded as one of most promising way to increase both coverage and capacity of future cellular network. Small cell technology enables to improve capacity of cellular radio network by tight cooperation between small cell and macro cell in multi-tier network where small cells are densely deployed within macro cell coverage. In this paper, we describe the deployment scenarios for cooperation between macro cell and small cells and state-of-the-art technologies related to dense small cell deployment. Then, we also provide design principles and standardization trends for small cell enhancement in 3GPP.

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Analysis of Forwarding Schemes to Mitigate Data Broadcast Storm in Connected Vehicles over VNDN

  • Hur, Daewon;Lim, Huhnkuk
    • Journal of the Korea Society of Computer and Information
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    • v.26 no.3
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    • pp.69-75
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    • 2021
  • Limitation of the TCP/IP network technology included in the vehicle communication is due to the frequent mobility of the vehicle, the increase in intermittent connection requirements, and the constant presence of the possibility of vehicle hacking. VNDN technology enables the transfer of the name you are looking for using textual information without the need for vehicle identifiers like IP/ID. In addition, intermittent connectivity communication is possible rather than end-to-end connection communication. The data itself is the subject of communication based on name-based forwarding using two types of packets: Interest packet and Data packet. One of the issues to be solved for the realization of infotainment services under the VNDN environment is the traffic explosion caused by data broadcasting. In this paper, we analyze and compare the existing technologies to reduce the data broadcast storm. Through this, we derive and analyze the requirements for presenting the best data mitigation technique for solving the data explosion phenomenon in the VNDN environment. We expect this paper can be utilized as prior knowledge in researching improved forwarding techniques to resolve the data broadcast explosion in connected vehicles over NDN.

Synergistically Enhanced Oxygen Evolution Catalysis with Surface Modified Halloysite Nanotube

  • Hyeongwon Jeong;Bharat Sharma;Jae-ha Myung
    • Journal of Electrochemical Science and Technology
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    • v.14 no.1
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    • pp.96-104
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    • 2023
  • Synergistically increased oxygen evolution reaction (OER) of manganese oxide (MnO2) catalyst is introduced with surface-modified halloysite nanotube (Fe3O4-HNTs) structure. The flake shaped MnO2 catalyst is attached on the nanotube template (Fe3O4-HNTs) by series of wet chemical and hydrothermal method. The strong interaction between MnO2 and Fe3O4-HNTs maximized active surface area and inter-connectivity for festinate charge transfer reaction for OER. The synergistical effect between Fe3O4 layer and MnO2 catalyst enhance the Mn3+/Mn4+ ratio by partial replacement of Mn ions with Fe. The relatively increased Mn3+/Mn4+ ratio on MnO2@FHNTs induced 𝜎* orbital (eg) occupation close to single electron, improving the OER performances. The MnO2@FHNTs catalyst exhibited the reduced overpotential of 0.42 V (E vs. RHE) at 10 mA/cm2 and Tafel slope of (99 mV/dec), compared with that of MnO2 with unmodified HNTs (0.65 V, 219 mV/dec) and pristine MnO2 (0.53 V, 205 mV/dec). The present study provides simple and innovative method to fabricate nano fiberized OER catalyst for a broad application of energy conversion and storage systems.

A Study on the Optimum Design of Piled-raft Foundation Considering Pile Head Condition (말뚝두부구속조건을 고려한 말뚝지지 전면기초의 최적단면 설계)

  • Cho, Jae-Yeon;Lee, Sung-June;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.26 no.12
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    • pp.31-40
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    • 2010
  • This study describes the three-dimensional behavior of pile foundations based on a numerical study. A series of numerical analyses were performed for connectivity conditions between piles and cap under vertical and lateral loadings. It is shown that a fixed connection between pile and cap is able to transfer significant bending moment through the connection and increases the pile lateral stiffness and the bending moment. Based on the results obtained, it was found that the cross sectional shear force in the raft with fixed head condition was larger than that of pinned head condition. Thus, the reinforcement of pile head and thickness of the raft also increases in fixed pile head condition. From the results, it is found that the overall behavior and cross sectional forces of pile foundations is affected significantly by the pile head conditions. Furthermore, the design of pile foundations with pinned head condition was judged to be less costly and very useful for preliminary design stages.

Understanding of the Duplex Thrust System - Application to the Yeongwol Thrust System, Taebaeksan Zone, Okcheon Belt (듀플렉스트러스트시스템의이해 - 옥천대태백산지역영월트러스트시스템에의 적용)

  • Jang, Yirang
    • Economic and Environmental Geology
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    • v.52 no.5
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    • pp.395-407
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    • 2019
  • The duplex system has been considered as an important slip-transfer mechanism to evaluate the evolution of orogenic belts. Duplexes are generally found in the hinterland portion of fold-thrust belts and accommodate large amounts of total shortening. Thus, understanding its geometric and kinematic evolution can give information to evaluate the evolution of the entire orogenic belt. Duplexes are recognized as closed-loop thrust traces on map view, indicating higher connectivity than imbricate fans. As originally defined, a duplex is an array of thrust horses which are surrounded by thrust faults including the floor and roof thrusts, and imbricate faults between them. Duplexes can accommodate regional layer-parallel shortening and transfer slip from a floor thrust to a roof thrust. However, an imbricate fault is not the only mean for layer-parallel shortening (LPS) and displacement transfer within duplexes. LPS cleavages and detachment folds can also play the same role. From this aspect, a duplex can be divided into three types; 1) fault duplex, 2) cleavage duplex and 3) fold duplex. Fault duplex can further be subdivided into the Boyer-type duplex, which was firstly designed duplex system in the 1980s that widely applied most of the major fold-thrust belts in the world, and connecting splay duplex, which has different time order in the emplacement of horses from those of the Boyer-type. On the contrary, the cleavage and fold duplexes are newly defined types based on some selected examples. In the Korean Peninsula, the Yeongwol area, the western part of the Taebaeksan Zone of the Okcheon Belt, gives an excellent natural laboratory to study the structural geometry and kinematics of the closed-loops by thrust fault traces in terms of a duplex system. In the previous study, the Yeongwol thrust system was interpreted by alternative duplex models; a Boyer-type hinterland-dipping duplex vs. a combination of major imbricate thrusts and their connecting splays. Although the high angled beds and thrusts as well as different stratigraphic packages within the horses of the Yeongwol duplex system may prefer the later complicate model, currently, we cannot choose one simple answer between the models because of the lack of direct field evidence and time information. Therefore, further researches on the structural field investigations and geochronological analyses in the Yeongwol and adjacent areas should be carried out to test the possibility of applying the fold and cleavage duplex models to the Yeongwol thrust system, and it will eventually provide clues to solve the enigma of formation and its evolution of the Okcheon Belt.