• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.198-205
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• 2005

Recently, the systems using multiple sensors such as magnetic, acoustic and pressure sensor are used for detection of underwater objects or vehicles. Those systems have difficulty of maintenance and repair because they operate underwater. Thus, this paper describes a hybrid detection system with long term operating reliability. This has a multi-signal transmission structure to have a high reliability. First, a signal transmission & receiving part, which transfers data from underwater sensors to land and receive control message from land through optical cable, has 4 multi-path. Second, the nodes for signal transmission are connected dually each other with single-hop construction and sensors are connected to a couple of neighboring nodes. This enables the output signal to transmit from a node to the next node and the next but one node together. Also, the signal from a sensor can be transmitted to two nodes at the same time. Therefore, the system with this construction has high reliability in long term operation because it makes possible to transmit sensor data to another node which works normally although a transmission node or cable in system have some faults.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.13-19
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• 2004

A system for detecting underwater target demands a high operational reliability because of the difficulty of maintenance and repair when the system has a few troubles during long operating period. Therefore, in this paper, we have proposed a signal transport system with a high reliability in an underwater sensor array system composed of magnetic and acoustic sensors. In this system, the nodes for signal transport are connected dually each other with single-hop construction and a magnetic sensor is connected to a couple of neighboring nodes. This enables the output signal to transport from a node to the next node and the next but one node. Also, the signal from a magnetic sensor can be transported to two nodes at the same time. Thus, the system with this construction makes possible to transport sensor data to another node which works normally when a transport node or cable have some faults and will operate normally although it happens some problems in a few signal transport nodes and connection cables.

• 전기의세계
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• v.17 no.2
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• pp.11-15
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• 1968

One of the most important methods used in the modern analysis of linear networks and systems is the signal flow graph technique, first introduced by S.J. Mason in 1953. In essence, the signal-flow graph technique is a graphical method of solving a set of simultaneous. It can, therefore, be regarded as an alternative to the substitution method or the conventional matrix method. Since a flow-graph is the pictorial representation of a set of equations, it has an obvious advantage, i.e., it describes the flow of signals from one point of a system to another. Thus it provides cause-and-effect relationship between signals. And it often significantly reduces the work involved, and also yields an easy, systematic manipulation of variables of interest. Mason's formula is very powerful, but it is applicable only when the desired quantity is the transmission gain between the source node and sink node. In this paper, author summarizes the signal-flow graph technique, and stipulates three rules for conversion of an arbitrary nonsource node into a source node. Then heuses the conversion rules to obtain various quantities, i.e., networks gains, functions and parameters, through simple graphical manipulations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.10
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• pp.4223-4249
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• 2015

A novel jamming detection technique to detect the presence of jamming in the downstream direction for cluster based wireless sensor networks is proposed in this paper. The proposed technique is deployed in base station and in cluster heads. The proposed technique is novel in two aspects: Firstly, whenever a cluster head receives a packet it verifies whether the source node is legitimate node or new node. Secondly if a source node is declared as new node in the first step, then this technique observes the behavior of the new node to find whether the new node is legitimate node or jammed node. In order to monitor the behavior of the existing node and new node, the second step uses two metrics namely packet delivery ratio (PDR) and received signal strength indicator (RSSI). The rationality of using PDR and RSSI is presented by performing statistical test. PDR and RSSI of every member in the cluster is measured and assessed by the cluster head. And finally the cluster head determines whether the members of the cluster are jammed or not. The CH can detect the presence of jamming in the cluster at member level. The base station can detect the presence of jamming in the wireless sensor network at CH level. The simulation result shows that the proposed technique performs extremely well and achieves jamming detection rate as high as 99.85%.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.569-576
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• 2014

Sensor node means a device to include sensor, amplifier, and data acquisition (DAQ) equipment. The sensor converts physical signals to electric signals and weak signals from the sensor can be amplified through the amplifier. DAQ equipment converts analog signal to digital signal and collects converted digital signal. Since the sensor node is sensitive to the environment so that selection of mounting position and fixture design of sensor are applied differently depending on the characteristics of a target. This study is about designing and manufacturing sensor node to be used in a machine tool. The environment of machine tool is very severe due to noise, temperature fluctuation, and dust, etc. Hence, the sensor and amplifier must be designed and manufactured by considering the environmental issues. The designed and manufactured sensor node was tested for the reliability and effectiveness of the developed sensor nodes in the study.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.518-521
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• 2007

The functional wireless sensor node for u-healthcare application was developed. The developed sensor node can check the abnormality of ECG in some simple software in ROM of microprocess in the sensor node. The ECG signal is one of very important health signal form human body, and wavelike signal which is sampled as a sampling frequency between 100 and 400 Hz for digitalization, so the wireless data dor ECG signal is some heavy in Zigbee communication. Thus the sensor send the ECG signal to other sensor nodes or base station when it find abnormality in ECG signal is key technology to reduce the traffic between sensor nodes in wireless sensor network for u-healthcare, The sensor node does not need to transmit ECG data all time in wireless sensor network and to server. Using these sensor nodes, the healthcare system can dramatically reduce wireless data packet overload, the power consumption of battery in the sensor nodes and thus increase the reliability of the wireless system.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.211-218
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• 2006

The Mobile IPv6 provides the enhanced internet services to user by supporting a node's mobility. In Mobile IPv6(MIPv6), the mobile node sends the binding message which binds home address(HoA) with care-of address(CoA) to the home agent whenever it changes its point of attachment to the internet. To reduce the mobility management signal message the Paging Hierarchical Mobile IPv6(PHMIPv6) is proposed. The mobile node does not send the binding message within the domain if the mobile node's state is idle. Therefore the mobility signal message cost can be reduced. However, when the mobile node's session arrival rate is high the many mobility management signal cost are needed because the paging cost is very high. In this paper, we analysis the drawback of PHMIPv6 and propose the scheme which can reduce the mobility management signal cost. The proposed scheme works independent of the number of subnet in the domain. Therefore the proposed scheme can improve the mobile node's mobility management scheme.

• ETRI Journal
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• v.29 no.5
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• pp.682-684
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• 2007

A new scheme to alleviate contention in optical burst switching networks is proposed. It consists of preventively reserving resources in a node, to be used if resources are busy on the next hop node. The burst is sent back to the preceding node and then resent forward. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution based on deflection routing.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.445-448
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• 2003

This paper presents a novel iris recognition method using wavelet transform and curve simplification. One-dimensional signals, which are calculated over circles on the iris, are decomposed into a multiple frequency bands. Each decomposed signal is approximated by a piecewise linear curve connecting node points. The curve is simplified by progressively removing unimportant node points while keeping the shape of the curve. Finally, a small number of node points represent features of each signal. Experiment results show that the presented method results in good performance in various noise environments.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.4
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• pp.31-37
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• 2008

Conventional cooperative communications can attain gain of spatial diversity and path loss reduction because destination node independently received same signal from source node and relay node located between source node and destination node. However, these techniques bring about decreased spectral efficiency with relay node and increased complexity of receiver by using maximal ratio combining (MRC). This paper has proposed cooperative ARQ protocol that can improve the above problems and can get the better performance. This method can increase the spectral efficiency than conventional cooperative communication because if the received signal from source node is satisfied by the destination preferentially, the destination transmits ACK message to both relay node and source node and then recovers the received signal. In addition, if ARQ message indicates NACK relay node operates selective retransmission and we can increase reliability of system compared with that of general ARQ protocol in which source node retransmits data. In the proposed protocol, the selective retransmission and ARQ message are to be determined by comparing log-likelihood ratio (LLR) computation of received signal from source node with predetermined threshold values. Therefore, this protocol don't waste redundant bandwidth with CRC code and can reduce complexity of receiver without MRC. We verified spectral efficiency and BER performance for the proposed protocol through Monte-Carlo simulation over Rayleigh fading plus AWGN.