• Proceedings of the IEEK Conference
• /
• 2004.06a
• /
• pp.95-98
• /
• 2004

In this paper, the hardware design of a transmission convergence sublayer(TC) for boradband wireless access system is described, which performs (1) formatting TC PDUs to MAC PDUs, (2) RS encoding/decoding, (3) providing various control signal to PHY modem. The TC hardware has been designed in VHDL, and successfully synthesized in an FPGA chip.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.7
• /
• pp.398-400
• /
• 2014

In this letter, we propose a cross-layer technique jointly considering modulation coding schemes (MCSs) of medium access control (MAC) layer, source significance information (SSI) and error concealment unit of application (APP) layer, and channel quality information (CQI) of physical (PHY) layer. We demonstrate the improved video quality by the proposed technique when H.264 videos are streamed over Rayleigh fading wireless channels.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.167-168
• /
• 2008

We suggest a phy layer of a sensor node. The proposed sensor nodes work well around metal or liquids because they operate at low frequency. In addition we present a demodulation algorithm for simultaneously decoding multiple received signals and a simulation result.

• Electronics and Telecommunications Trends
• /
• v.24 no.1
• /
• pp.43-49
• /
• 2009

최근 높은 대역폭을 요구하는 다양한 IP 멀티미디어 애플리케이션이 증가하면서 10G 이더넷 서비스가 폭넓게 이용되고 있으나, 이도 가까운 시기에 트래픽의 한계에 이를 것에 대비하여 보다 큰 대역폭을 제공할 수 있는 40G급 이더넷 기술에 관한 표준화 드래프트 1.0 규격이 이더넷은 IEEE 802.3ba에 의해 2008년 9월 완성되었으며 2009년 완료를 목표로 하고 있다. 본 고에서는 표준화 기술이 어떻게 채택되고 있는지를 알아보고, 40G 표준화 이더넷 백플레인 기술 및 등화기 구현방안에 대하여 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38C no.3
• /
• pp.239-246
• /
• 2013

The IEEE 802.15.4 offers standard about PHY and MAC layer and features low power, low bandwidth, and low speed data communication. Because of this reason, IEEE 802.15.4 is only within a limited range such as sensor detection and home network; nevertheless, the research about transmission multimedia data like voice packet through wireless sensor networks is conducted widely. In this paper, we proposed the group communication system based on the sensor network. TDMA/TDD MAC based on the IEEE 802.15.4 PHY for voice communication on the sensor network is designed by improvement existing peer-to-peer voice communication on the sensor network and hardware is implemented for group communication. To measure the quality of designed system, mean opinion score (MOS) is obtained from the experiment and verified by using sine wave method. As a result of an experiment, we expect that a many cases of application solution can be developed using presented system.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.38 no.6
• /
• pp.11-17
• /
• 2001

Design and implementation of the MAC protocol processor prototype for high speed wireless LAN, which has interface with 5GHz OFDM PHY layer, is presented. We analyze the IEEE 802.11 MAC protocol specification and then separate the MAC protocol functions to be implemented by hardware and firmware and define the interface in which frames can be exchanged. That is, it is considered that high speed queue processing and interfaces with RISC processor and OFDM PHY layer. Protocol control and transmission/reception functions of the MAC functions are implemented in hardware in order to guarantee high speed processing in MAC layer. The developed MAC hardware block operates at 10MHz main clock. Therefore, transmission rate in PHY layer is about 80Mbps because data transmission/reception between MAC layer and PHY layer is performed as unit of octet. The designed FPGA MAC function chip has been implemented in wireless LAN test board and it is verified that DCF function is operated correctly.

• The Journal of the Korea Contents Association
• /
• v.9 no.7
• /
• pp.67-75
• /
• 2009

IEEE 802.11 WLAN(Wireless Local Area Network) standard is currently developing with increased wireless internet demand. Study trends of IEEE 802.11n for high throughput 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 PRY(Physical) layer. But, no one demonstrates IEEE 802.11n system performance results considering MAC and PRY connection. This paper adapts A-MPDU(Aggregation-MAC Protocol Data Unit) method in MAC layer and MIMO in PRY layer for IEEE 802.11n system. Consequently, Simulation results show enhanced throughput and data rates compared to existing system. Also, We use NS-2(Network Simulator-2) considering MAC and PRY connection for reality.

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

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.21 no.3
• /
• pp.176-183
• /
• 2018

Purpose: Acute gastroenteritis (AGE) is a major cause of morbidity and remains a major cause of hospitalization. Following the Syrian refugee crisis and insufficient clean water in the region, this study reviews the etiological and epidemiological data in Lebanon. Methods: We prospectively analyzed demographic, clinical and routine laboratory data of 198 children from the age of 1 month to 10 years old who were admitted with the diagnosis of AGE to a private tertiary care hospital located in the district of Nabatieh in south Lebanon. Results: Males had a higher incidence of AGE (57.1%). Pathogens were detected in 57.6% (n=114) of admitted patients, among them single pathogens were found in 51.0% (n=101) of cases that consisted of: Entamoeba histolytica 26.3% (n=52), rotavirus 18.7% (n=37), adenovirus 6.1% (n=12) and mixed co-pathogens found in 6.6% (n=13). Breast-fed children were significantly less prone to rotavirus (p=0.041). Moreover, children who had received the rotavirus vaccine were significantly less prone to rotavirus (p=0.032). Conclusion: Our findings highlight the high prevalence of E. histolytica infection as the major cause of pediatric gastroenteritis in hospitalized children, during the summer period likely reflecting the insanitary water supplies and lack of hygiene. Moreover the 42.4% of unidentified causative pathogens should prompt us to widen our diagnostic laboratory arsenal by adopting new diagnostic technologies.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.556-563
• /
• 1997

The endogenous gibberellin(GA) levels of sorghum grown under different photoperiodic conditions were measured by GC-MS-SIM. The effect of photoperiods on the diurnal GA levels of the 13-hydroxylation pathway was investigated by sampling every 6 h for 1 day. Levels of $GA_12$, $GA_53$, $GA_19$, $GA_20$, $GA_1$ and $GA_8$ were not constant throughout sampling times but rather rhythmic in productions. Wild-type seedlings grown under short photoperiod contained more $GA_20$ and $GA_1$ than those of long photoperiod. Although plant height of phyB-l(phytochrome B mutant) was taller than wild-type under all photoperiods tested, $GA_1$ concentration of wild-type grown under 10 h photoperiod was higher than that of phyB-l grown under the same photoperiod. These results are compatible with the idea that phytochrome B changed seedling responsiveness to GAs.