• Bulletin of the Society of Naval Architects of Korea
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• v.55 no.3
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• pp.26-28
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• 2018

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.37-40
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• 2004

This paper is about Multi-function RFID Reader Platform that receives RF TAC data and transfer data to HOST PC through Blue-Tooth USB, RS-232 and Ethernet. This Reader system is composed of RFID Module, ARM Processor, RS-232, US5 and Ethernet Interface, etc.. The information of Tag stretches the RFID module through the antenna and is received at the ARM processor. ARM processor accomplishes the facility to deliver these informations at the PC server using the Blue-tooth Interface for the wireless and the RS-232, USB and Ethernet MAC Interface for the wire.

• Information and Communications Magazine
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• v.30 no.6
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• pp.20-25
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• 2013

본고에서는 1GHz 이하 주파수에서 동작하는 Wireless LAN(WLAN) 표준으로, IEEE 802.11ah PHY/MAC 표준 규격에 대해서 알아 본다. IEEE 802.11ah 표준은, Smart Grid, M2M, IoT 와 같이 실내, 실외에서 많은 수의 단말들을 최소한의 전력소모로 데이터 통신을 하기 위한 목적으로 개발되었다. WLAN의 서비스 범위가 1Km 이상으로 늘어나게 되면, 그 동안 WLAN 에서 심각하게 다루지 않았던 Hidden Node 문제가 단말의 전력 소모, throughput performance 을 결정하는 중요한 요소로 등장하게 된다. 특별히 IEEE 802.11ah 에서는, 많은 수의 단말들간에 Hidden Node 을 고려한 Restricted Access Window 라는 새로운 channel access 기법이 제안되었고, 이에 본 고에서는 IEEE 802.11ah 에 새롭게 지원되는 MAC 기능들에 대해 중점적으로 살펴 보도록 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.27 no.1
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• pp.97-102
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• 2023

IoT is being used in a lot of industry domain such as smart home, smart ocean, smart energy, and smart farm, as well as legacy information services. For a server, an IoT device using the same protocol is a trusted object. Therefore, a malicious attacker can use an unauthorized IoT device to access IoT-based information services and access unauthorized important information, and then modify or extract it to the outside. In this study, to improve these problems, we propose an IoT device authentication system used in IoT-based information service. The IoT device authentication system proposed in this study applies identifier-based authentication such as MAC address. If the IoT device authentication function proposed in this study is used, only the authenticated IoT device can access the server. Since this study applies a method of terminating the session of an unauthorized IoT device, additional research on the access deny method, which is a more secure authentication method, is needed.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1109-1119
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• 2009

WLAN(Wireless Local Area Network) standard is currently developing with increased wireless internet demand. Though existing IEEE 802.11e demonstrates that data rates exceed 54Mbps with assuring QoS(Quality of Service), wireless internet users can't be satisfied with real communication system. After IEEE 802.11e system, Study trends of IEEE 802.11n show two aspects, enhanced system throughput using aggregation among packets in MAC (Medium Access Control) layer, and better data rates adapting MIMO(Multiple-Input Multiple-Output) in PHY(Physical) layer. But, no one demonstrates IEEE 802.11n system performance results considering MAC and PHY connection. Therefore, this paper adapts MIMO in PHY layer for IEEE 802.11n system based on A-MPDU(Aggregation-MAC Protocol Data Unit) method in MAC layer considering MAC and PHY connection. SVD(Singular Value Decomposition) method with WLAN MIMO TGn Channel is used to analyze MIMO. Consequently, Simulation results show enhanced throughput and data rates compared to existing system. Also, We use Ns-2(Network Simulator-2) considering MAC and PHY connection for reality.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.833-836
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• 1991

This paper proposes several types of 2-D interpolation lifters for HD-MAC decoder. Filters considered here are FIR, IIR, median, and FMH. Their structure and coefficients have been determined to be appropriate for real-time computation as well as to have good reconstructability. Results or computer simulation are also presented to show the performance of those filters.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.107-115
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• 2007

In general, wireless sensor networks composed of many nodes which are located in ad. hoc environment and send the gathered data to sink node support only one way traffic. In those cases, it is not possible to send commands to nodes to react for exceptional events because the networks can not deliver downward data and the nodes run in pre-assigned fixed schedule. This paper expands the WSLP to bidirectional WSLP and implements a fire monitoring system on it, and shows the feasibility of bidirectional USN by demonstrating the usability of the process of reaction to a fire in the implemented fire monitoring system.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.121-129
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• 2012

In this paper, we proposed WBAN system model to management an application that requires low rate data transfer in IEEE 802.15.4. We have to use different wireless sensor network technology to transfer different date rate and emergency message in medical application service. A suitable system model for WBAN and a WBAN MAC protocol in order to solve these existing system problems are proposed. Firstly, the priority queuing was applied to contention access period, and the system model which could guarantee transmission of a MAC command frame was proposed. Secondly, the MAC frame was newly defined to use the system model which was proposed above. Thirdly, WBAN CSMA/CA back-off algorithm based on data transmission rate was proposed to enhance data throughput and transmission probability of the data frame which does not have priority in the proposed WBAN system. The proposed algorithm is designed to be variable CSMA/CA algorithm parameter, depending on data rate. For the evaluation of WBAN CSMA/CA algorithm, we used Castalia. As a result of the simulation, it is found that the proposed system model can not only relieve loads of data processing, but also probability of collision was decreased.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.21 no.2
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• pp.89-107
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• 2017

In this paper, we have proposed a modified Marker-And-Cell (MAC) method to investigate the problem of an unsteady 2-D incompressible flow with heat and mass transfer at low, moderate, and high Reynolds numbers with no-slip and slip boundary conditions. We have used this method to solve the governing equations along with the boundary conditions and thereby to compute the flow variables, viz. u-velocity, v-velocity, P, T, and C. We have used the staggered grid approach of this method to discretize the governing equations of the problem. A modified MAC algorithm was proposed and used to compute the numerical solutions of the flow variables for Reynolds numbers Re = 10, 500, and 50000 in consonance with low, moderate, and high Reynolds numbers. We have also used appropriate Prandtl (Pr) and Schmidt (Sc) numbers in consistence with relevancy of the physical problem considered. We have executed this modified MAC algorithm with the aid of a computer program developed and run in C compiler. We have also computed numerical solutions of local Nusselt (Nu) and Sherwood (Sh) numbers along the horizontal line through the geometric center at low, moderate, and high Reynolds numbers for fixed Pr = 6.62 and Sc = 340 for two grid systems at time t = 0.0001s. Our numerical solutions for u and v velocities along the vertical and horizontal line through the geometric center of the square cavity for Re = 100 has been compared with benchmark solutions available in the literature and it has been found that they are in good agreement. The present numerical results indicate that, as we move along the horizontal line through the geometric center of the domain, we observed that, the heat and mass transfer decreases up to the geometric center. It, then, increases symmetrically.

• Communications of the Korean Mathematical Society
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• v.17 no.4
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• pp.681-691
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• 2002

We study categorical properties of the category SWQOS (S$\^$U/WQOS, S$\^$L/WQOS, resp) of (upper, lower, resp.) semi-continuous quasi-ordered spaces and the subcategory SWPOS (S$\^$U/WPOS, S$\^$L/WPOS, resp.) of (upper, lower, resp.) semicontinuous partially ordered spaces. We show that the categories S$\^$U/WPOS, S$\^$L/WPOS and SWPOS are closed under the formation of initial mono-sources in the category TQOS of topological quasi-ordered spaces, and they we mono-topological, complete and cocomplete epireflective subcategories of the category TQOS. We obtain their MacNeille and universal initial completions, as well as those of subcatego.ies S$\^$U/WQOS(S$\^$L/WQOS) and SWQOS, in which the topologies are T$\_$0/ and T$_1$, respectively.