• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.10B
• /
• pp.849-856
• /
• 2004

This paper proposes a novel superframe formation algorithm for wireless systems with time-slotted superframe structure. The design objective of the proposed algorithm is to provide high performance, stability, error tolerance, as well as power-saving features. The paper presents a comprehensive performance analysis of the Proposed superframe formation algorithm with different types of traffic applied. During analysis several performance metrics are investigated. The error tolerance to beacon loss and the behavior of CBR flows are also studied. We show that the proposed algorithm inherits the advantages of the previously used algorithms, while providing additional features.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.181-184
• /
• 1996

This paper deals with the design problem of model reference adaptive controllers for MIMO plants with unknown orders. A design scheme for an adaptive control system based on CGT theorem, which has hierarchical structures derived from backstepping strategies, is proposed for MIMO plants with unknown orders but with known relative MacMillan degrees(relative degrees for SISO plants). It is also shown that all the signals in the resulting control system are bounded, and that the asymptotic tracking is achieved in the case where reference inputs are step.

• Journal of Industrial Technology
• /
• v.25 no.B
• /
• pp.211-220
• /
• 2005

The wireless sensor network consists of a number of sensor nodes which have physical constraints. Each sensor node senses surrounding environments and sends the sensed information to Sink. The inherent vulnerability in security of the sensor nodes has promoted the needs for the lightweight security protocol. In this paper, we propose a non-hierarchical sensor network and a security protocol that is suitable for monitoring the man-made objects such as bridges. Furthermore, we present the efficient way of setting the routing path by storing IDs, MAC(message authentication code) and the location information of the nodes, and taking advantage of the two node states, Sleep and Awake. This also will result in the reduced energy consuming rate.

• Korean Journal of Child Studies
• /
• v.29 no.3
• /
• pp.157-174
• /
• 2008

This study used the person-oriented approach to explore differences in narrative representations of 97 4-, 5- and 6-year old children (30 foster care, 40 biological family, 17 adopted). Using the MacArthur Story Stem Battery (Bretherton et al., 1990), observations were made to obtain children's narrative representations of content themes and performances. Descriptive statistics, ANOV A and hierarchical cluster analyses were performed. The results of this study were that : (1) Biological family children showed more empathy/helping representations. Foster care children and adopted children showed more anxious representations, and foster care children showed more dysregulated aggression. (2) Four clusters of foster care and adopted children and five clusters of family biological children were found.

• Journal of the Korea Society for Simulation
• /
• v.1 no.1
• /
• pp.87-102
• /
• 1992

This paper presents the development of event-driven system level simulation tool SMPLE(Smpl Extende, an extention fo smpl) and its application to the performance analysis of multiprocessor computer systems. Because of its data structure, it is very difficult to change, expand or add new functions to simulation language smpl implemented by MacDougall. In SMPLE, we change data structure with structure and pointer, add new functions, and enable dynamic memory management. Using new data structure, facilities, and functions added in SMPLE, we simulate job processing of a shared bus multiprocessor system with autonomous hierarchical I/O subsystem. We set system performance contribution of subsystems and units. The impact of disk I/O on system performance is evaluated under vairous conditions of number of processors, processing power, memory access time and disk seek time.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.5
• /
• pp.1087-1095
• /
• 2014

A recent major development in computer technology is the advent of the wearable computer system that is based on human-centric interface technology trends and ubiquitous computing environments. Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that can differentiate QoS of U-health WBAN and WUSB traffic with different priorities is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. In our proposal and performance evaluation, throughputs of U-health WBAN and WUSB traffic are analyzed under single and multiple QoS classes to evaluate the effectiveness of proposed QoS differentiating structure in WUSB over IEEE 802.15.6.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.7
• /
• pp.303-312
• /
• 2006

This paper proposes the architecture and protocol of a data communication network for the safety system in nuclear power plants. First, we establish four design criteria with respect to determinability, reliability, separation and isolation, and verification/validation. Next we construct the architecture of the safety network for the following systems: PPS (Plant Protection System), ESF-CCS (Engineered Safety Features-Component Control System) and CPCS (Core Protection Calculator System). The safety network consists of 12 sub-networks and takes the form of a hierarchical star. Among 163 communication nodes are about 1600 origin-destination (OD) pairs created on their traffic demands. The OD pairs are allowed to exchange data only during the pre-assigned time slots. Finally, the communication protocol is designed in consideration of design factors for the safety network. The design factors include a network topology of star, fiber-optic transmission media, synchronous data transfer mode, point-to-point link configuration, and a periodic transmission schedule etc. The resulting protocol is the modification of IEEE 802.15.4 (LR-WPAN) MAC combined with IEEE 802.3 (Fast Ethernet) PHY. The MAC layer of IEEE 802.15.4 is simplified by eliminating some unnecessary (unctions. Most importantly, the optional TDMA-like scheme called the guaranteed time slot (GTS) is changed to be mandatory to guarantee the periodic data transfer. The proposed protocol is formally specified using the SDL. By performing simulations and validations using Telelogic Tau SDL Suite, we find that the proposed safety protocol fits well with the characteristics and the requirements of the safety system in nuclear power plants.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.165-170
• /
• 2007

The main goal of research concerning clustering protocols is to minimize the energy consumption of each node and maximize the network lifetime of wireless sensor networks. However, most existing clustering protocols mainly focused on the design and formation of clusters, leaving the consideration of communication between the cluster head and the sink behind. In this paper, we propose efficient multi path routing algorithm by using MAC-NET Cross-layering. multi path needed only one tiny packet from sink to setup. In addition proposed algorithm can be used for any cluster-based hierarchical inter-clustering routing algorithm. The simulation results demonstrate that proposed algorithm extended the overall survival time of the network by reducing the load of cluster heads. The performance of proposed algorithm is less affected by the extension of sensing field than other inter-clustering operation.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.7
• /
• pp.1619-1627
• /
• 2014

Wearable computer systems can use the wireless universal serial bus (WUSB) that refers to USB technology that is merged with WiMedia PHY/MAC technical specifications. In this paper, we focus on an integrated system of the wireless USB over the IEEE 802.15.6 wireless body area networks (WBAN) for wireless wearable computer systems supporting U-health services. And a communication structure that performs the time-synchronization is proposed for WUSB over IEEE 802.15.6 hierarchical protocol. Proposed time-synchronization mechanisms adopt the WBAN Polling Access and combine it with a time-synchronization middleware using time stamps. In our performance evaluations, time-synchronization performances with only WBAN Polling Access scheme are analyzed first. After that, performances combined with the time-synchronization middleware are analyzed to evaluate the effectiveness of proposed time-synchronization structure in WUSB over IEEE 802.15.6.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.7
• /
• pp.213-220
• /
• 2008

In a distributed processing environment composed of many independent systems connected by networks, it is very important and difficult to make time synchronization between the systems. Especially in the USN environment the time synchronization is still more difficult than in general distributed processing environment because energy is limited and communication function is feeble. Even though of these difficulties, the USN environment requires higher precision of time synchronization. We of the typical applications requesting very strict time synchronization in USN is TDMA MAC. This paper proposes and evaluates a new time synchronization protocol HTSP(Hierarchical Time Synchronization Protocol) which is an advanced version of the FTSP(Flooding Time Synchronization Protocol) published recently. The time synchronization precision of the HTSP is equal to that of the FTSP, but the energy consumption of the HTSP is lower than that of the FTSP owing to the reduced number of broadcast messages. The simulation results show that the energy consumption of the HTSP is only 74% of that of the FTSP.