• The Journal of the Korean Society for Microbiology
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• v.18 no.1
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• pp.47-52
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• 1983

During the last three years, it has become evident that patients with tuberculosis-like diseases due to the Mycobacterium avium-intracellulare complex(referred to M. avium complex; MAC) in Korea are more frequently observed than were assumed earlier. However, the incidence of various serotypes of the MAC isolated from patients with tuberculosis-like diseases has not been clarified. In this study, the serotypes of 16 strains of the MAC isolated from sputa of persons who had radiographic abnormalities of the lungs were determined by bacterial agglutination test with reference sera. The serotypable strains belonged to 7 serotypes, i.e., M. avium 13 were 4 strains(25.0%), M. avium 8 and 14 each 3 strains(18.8%), M. avium 5, 7, 12 and 18 one strain(6.3%), respectively. Two strains(12.5%) were not typable.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.87-91
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• 2010

The IEEE 802.15.4 and IEEE 802.15.7 standard are the typical of low rate wireless and Visible Light Wireless personal area networks. Its Medium Access Control protocol can support the QoS traffic flows for real-time application through guaranteed time slots (GTS) in beacon mode. However, how to achieve a best allocation scheme is not solved clearly. The current analytical models of IEEE 802.15.4 MAC reported in the literature have been mainly developed under the assumption of saturated traffic or non-bursty unsaturated traffic conditions. These assumptions don't capture the characteristics of bursty multimedia traffic. In this paper, we propose a new analytical model for GTS allocation with burst Markov modulated ON-OFF arrival traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.429-436
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• 2011

The G-PON is an efficient solution to implement the FTTH and have GEM frame to accomodate various protocols like Ethernet frames, IP packets, and TDM signals. Above all, the Ethernet is one of the most widely used 2nd layer protocol in the campus, the subscriber access, and the carrier service. So G-PON system has to provide an Ethernet interface with top priority. In this paper, we implement a gigabit Ethernet adapter based on Ethernet over GEM in the ITU-T G.984.3 to accommodate Ethernet protocol in the G-PON TC chip. The adapter maps each Ethernet frame to a single or multiple GEM frames and has several functions including generation of the GEM header, encapsulation of frames and the SAR. In particular, the adapter have converter (LUT) MAC address to port-ID which is a key to identify logical connections though it is not defined in specification but important. We implement the adapter with a FPGA and verify the functions of segmentation and reassembling, MAC address learning, and throughput with the logic analyzer and the Ethernet analyzer.

• Magazine of the Korea Concrete Institute
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• v.2 no.3
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• pp.81-88
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• 1990

For the protectioon of radioactive leakage, the quality control of main concrete structure in nuclear power plants is very important. So, this studey is designed to analyze the influence of kind of cement and aggregate on the mechanical properties of high density concrete. Test results of this study are as follows; 1)The slump of magnetite aggregate concrete(MAC) is found half value of nat.ural aggregate concrete (NAC). 2)As the effect of cement, the compressive strength of concrete using moderate heat cement is found higher 5-19 % than that of ordinary portland cement. 3)As the effect of fine aggregate, t.he compressive strength of MAC is found higher than that. of NAC below 340kg/$cm^2$ and lower t.han NAC above 340kg/$cm^2$. 4)As the effect of coarse aggregate, the compressive strength of MAC is found higher 17-22% than that of NAC.

• Journal of KIISE
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• v.43 no.11
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• pp.1245-1258
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• 2016

Cryptographic technologies providing confidentiality and integrity such as encryption algorithms and message authentication codes (MACs) are necessary for preventing security threats in the Internet of Things (IoT) where various kinds of devices are interconnected. As a number of encryption schemes that have passed security verification are not necessarily suitable for low-power and low-performance IoT devices, various lightweight cryptographic schemes have been proposed. However, a study of lightweight MACs is not sufficient in comparison to that of lightweight block ciphers. Therefore, in this paper, we reviewed various kinds of MACs for their classification and analysis and then, we presented a new way for future MAC development. We also implemented major MAC algorithms and performed experiments to investigate their performance degradation on low-end micro-controllers.

• Journal of Digital Convergence
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• v.10 no.6
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• pp.225-230
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• 2012

When a car accident happened, the accident vehicle should broadcast a safe message to its neighbors in multi-hop. However, the pure flooding is difficult to protect a chain-reaction collision because of the frequent collision and the communication delay. To solve this problem, we proposes a back-off algorithm applied to the estimation of the neighbor node count using the t-distribution. And we proposes a MAC protocol preventing the communication delay by separating the neighbor's count collection channel and data channel. As a result, we show the frame reception success rate of our protocol improved more 10% than the previous protocol.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.2 s.302
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• pp.19-26
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• 2005

This paper is about designing and implementation of Multi-Function UHF RFID Reader Platform that receives and processes RFID tag data from the tags, and transmits the data to PC server through Bluetooth, USB, RS-232 or Ethernet. This reader system is composed of RFID module, ARM processor, RS-232 interface, USB, Ethernet MAC interface, Bluetooth etc.. This paper also provides a brief overview and concept of RFID reader, and proposes the design and implementations of the RFID reader platform. The paper evaluates and analyzes two practical implementations, fixed type and portable type.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2008-2015
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• 2010

Ns-2 is a proven simulator which is widely utilized to evaluate the performance of wired and wireless network. Ns-2.33 version introduced the extended version including the modules which the core functions of existing 802.11 PHY and MAC layer are implemented. However, if the error rate, one of most important parameters to evaluate a performance of wireless network, is applied to the extended version, the simulation is ceased with several fatal errors. Furthermore, a packet error is detected and discarded on MAC layer in the traditional protocol architecture, but there is the problem which can't identify information about a packet with error by processing packet error on PHY layer in this version. In this paper, we modify the extended version to resolve the above mentioned problems. And also we perform ns-2 simulation using the modified version on the IEEE 802.11p based vehicular ad-hoc networks, and then analyze effects of error rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.119-124
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• 2010

The MAC layer in ad-hoc network which makes network of nodes without infrastructure for a time has became an issue to reduce delay, allocate fairly bandwidth, control TX/RX power and improve throughput. Specially, the problem to reduce power consumption in ad-hoc network is very important part as ad-hoc devices use the limited battery. For solution of the problem, many power control algorithms, such as distribute power control, PCM (Power Control MAC) and F-PCF (Fragmentation based PCM), are proposed to limit power consumption until now. Although the algorithms are designed to minimize power consumption, the latency communication zone is generated by power control of RX/TX nodes. However the algorithms don't suitably reuse the space. In this paper proposes the algorithm to improve data throughput through Spatial Reuse based on a power control method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.162-169
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• 2009

Message Authentication Code (MAC) assures integrity of messages. In Mobile WiMAX, 128-bit Cipher-based MAC (CMAC) is calculated for management messages but only the least significant half is actually used truncating the most significant 64 bits. Naming these unused most significant 64bits Shared Authentication Information (SAI), we suggest that SAI can be applied to protect the network from DDoS attack which exploits idle mode vulnerabilities. Since SAI is the unused half of CMAC, it is as secure as 64bits of CMAC and no additional calculations are needed to obtain it. Moreover, SAI doesn't have to be exchanged through air interface and shared only among MS, BS, and ASN Gateway. With these good properties, SAI can efficiently reduce the overheads of BS and ASN GW under the DDoS attack.