• Journal of Advanced Navigation Technology
• /
• v.13 no.2
• /
• pp.224-230
• /
• 2009

In the latest date, medical body area networks (MBANs) are emerging as a new technology for diagnosis the human body. MBANs in the health care fields are based on short-range and low-power (e.g. ubiquitous computing) among small-sized devices, and have been used by means of medical services. In this paper, we proposed an emergency message transmission protocol using carrier sense multiple access/time division multiple access in MBANs. This scheme focuses on dependability and power-efficiency. In order to increase the reliability of the transmission, this scheme modified a MCTA slot of IEEE 802.15.3 standard to a SR-MCTA slot. SR-MCTA slot is assigned by MBAN coordinator according to requesting terminal nodes. The method, having the priority of transmission, occurs a collision packet randomly. Results from this proposed solution revel that reservation-based TDMA medical body area network(MBAN) protocol for transmitting emergency message was improved in terms of transmission delay.

• Journal of KIISE:Information Networking
• /
• v.37 no.2
• /
• pp.150-156
• /
• 2010

Audio watermarking is the process of embedding inaudible information in an audio signal and has been widely used for copyright protection. In this research, we use the audio watermarking not for copyright protection but for the transmission of side information for user convenience, presenting an algorithm suitable for this purpose. Our new algorithm includes watermark embedding/extraction methods during acoustic transmission through the air that employ energy modulation of the audio signal and an efficient two-step synchronization method. The proposed algorithm is evaluated in experiments of conveying information from audio speakers to a mobile phone. The results show that reliable transmission is possible within a 5m range, which is an improvement achieved by our algorithm as compared to the existing one.

• Journal of Computing Science and Engineering
• /
• v.8 no.2
• /
• pp.107-118
• /
• 2014

One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, such as RTS/CTS assumed to be sent at 1 Mbps. The 802.11 standard has been enhanced several times since then and now it supports multi-rate transmission up to 65 Mbps in the currently popular 802.11n (20 MHz channel, single stream with long guard interval). As a result, the difference in transmission rates and coverages between the data frame and control frame can be very large. However adjusting the RTS/CTS transmission rate to optimize network throughput has not been well investigated. In this paper, we propose a method to decrease the number of exposed nodes by increasing the RTS transmission rate to decrease RTS coverage. Our proposed method, Asymmetric Range by Multi-Rate Control (ARMRC), can decrease or even completely eliminate exposed nodes and improve the entire network throughput. Experimental results by simulation show that the network throughput in the proposed method is higher by 20% to 50% under certain conditions, and the proposed method is found to be effective in equalizing dispersion of throughput among nodes.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.6
• /
• pp.1083-1090
• /
• 2009

In 18GHz using unified data transmission in a subway and railway, Influence of the multipath fading is big and an arrival range of the micro wave takes the influence greatly according to the transmit angle and receive angle because it not diffracted. This thesis analyzed microwave property underground tunnel and ground railway at unified data transmission in subway and railway. Antenna gain of directional antenna many used unified transmission in an subway and railway, is used 15dBi and 10dBi in simulation. Transmitter's property is compared underground tunnel to ground railway about curved railway of R=100, R=200, R=400. Specification of transmitter is used sample unified transmission system in subway and railway of KRRI(korea railroad research Institute). Transmitter's power is 20dBm and Reciever's sensitivity is -90dBm. According to result of simulation.

• The Journal of the Korea Contents Association
• /
• v.6 no.12
• /
• pp.136-146
• /
• 2006

In Wireless Sensor Network(WSN) a sensor node transfers sensing data to the base-node through multi-hop because of the limited transmission range. Also because of the limited energy of the sensor node, the sensor nodes are required to consume their energy evenly to prolong the lifetime of the network. LMPR is a routing protocol for WSN, LMPR configures the network autonomously based on level which is the depth from the base-node, and distributes the transmission and computation load of the network to each sensor node. This paper implements LMPR on TinyOS and experiments on the performance of LMPR in WSN. As the result, the average of the received rate of LMPR is 91.39% and LMPR distributes the load of the transmission and computation about 4.6 times compare to the shortest cost routing protocol. We expect LMPR evenly distributes the transmission and computation load of the network to each node, and the lifetime of the network will be longer than it used to be.

• Journal of Digital Contents Society
• /
• v.19 no.5
• /
• pp.963-969
• /
• 2018

Wi-Fi and Bluetooth technologies are perhaps the most prominent examples of wireless communication technologies used in the Internet of Things (IoT) environment. Compared to widely used Wi-Fi, Bluetooth technology has some flaws including 1:1 connection (one-way) between Master and Slave, slow transmission, and limited connection range; Bluetooth is mainly used for connecting audio devices. Since the release of Bluetooth Low Energy (BLE), some of the flaws of Bluetooth technology have been improved but it still failed to become a competitive alternative of Wi-Fi. This paper presents a method of data transmission through broadcasting in BLE and demonstrates its performance, one-to-many data transfer result. The Connection-Free Data Transmission proposed in this paper will hopefully be utilized in special circumstances requiring 1:N data transmission or disaster security network.

• Composites Research
• /
• v.28 no.6
• /
• pp.389-394
• /
• 2015

The sound absorption coefficient and sound transmission loss of graphite intercalation compound (GIC) included epoxy composites were investigated. Epoxy resin was infused into the expanded GIC and the impedance tube method was employed to measure the sound absorption coefficient and sound transmission loss. Scanning electron microscopy photographs showed uniform distribution of the GIC in the epoxy matrix. The surface density of epoxy/GIC (20 wt%) composites decreased about 56% compared to that of pure epoxy. The sound absorption coefficient of composites increased about 3 times at the frequency range of 500~1000 Hz compared to the pure epoxy. The sound transmission loss of composites decreased with increasing the GIC content and it is attributed to the increase of pores in the composites.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37A no.9
• /
• pp.762-771
• /
• 2012

In this paper, we propose an adaptive power control scheme employing a self-optimization concept in femtocell systems, in order to improve system capacity, thereby reducing call-drop probability. In the proposed scheme, each femto base station(FBS) controls individual channel's transmission power base on two parameters; the neighboring cell's transmission power for each individual channel which is delivered from a femto-gateway and the received power strength from neighboring cells which is periodically measured by means of a spectrum sensing. Adaptive adjustment of individual channel's transmission power in accordance with femto mobile station(FMS) mobility features can also reduce undesirable handovers and evenly distribute traffic load over all femtocells. In addition, the manipulative control of channel's transmission power is able to keep the system coverage and the call-drop probability within an acceptable range, regardless of density of femtocells. Computer simulation shows that the proposed scheme outperforms existing schemes in terms of the system coverage and the call-drop probability.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.12
• /
• pp.2518-2524
• /
• 2009

This paper presents the backplane effects due to a rectangular aperture size for two-wire transmission line with equal line length crossing the changeable rectangular aperture in an infinite ground backplane. It is used to determine the characteristics of the backplane insertion loss of the transmission line from the load section in accordance with the backplane aperture size. The results show that the insertion gain and insertion loss are obtained for the specific frequency range when the transmission line is closed to the backplane aperture size. The insertion loss is decreased that the aperture horizontal length and vertical length is more than a=50 mm and b=20 mm. The measurements of insertion loss are performed to verify the theoretical analysis.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.11
• /
• pp.42-48
• /
• 2020

The agricultural tractor is a multi-purpose vehicle, which is frequently used in the agricultural field. It must be highly reliable in terms of human safety. Design and analysis of agricultural tractors must be performed using actual agricultural workload to maintain high reliability. Additionally, the frequency with which various components and systems are used must also be taken into consideration. In this study, a tractor is built to measure its workload in the actual field. Further, the measured load was analyzed for various farming tasks. The range of ratios of consumed power to engine power was measured to be 42.6%-87.2%, 75.1%-97%, 26.5%-59.2% for a plow, rotary, and harvest tasks, respectively. The results were fed into a transmission simulation model to analyze the strength and life of the transmission components. We conclude that a more reliable product can be constructed by incorporating the transmission analyses using the actual load.