Jae-Choong Nam

Design and development of a u-Health system based on the ISO/IEEE 11073 PHD standards

An increase in human life expectancy due to the development of medical techniques has led to many social problems such as rapidly aging populations in many industrialized countries, increased medical expenses and a lack of medical specialists. Thus, studies on improving the quality of life with the least amount of expense have been conducted by incorporating advanced technology, especially for PHDs (Personal Health Device), into the medical service market. Recently, the Continua Alliance, IEEE Standards Association, and the IEEE-EMBS affiliated 11073 Personal Health Data Working Group have been studying techniques to guarantee the compatible extensibility of the u-Health system by defining standards, which manage and send information from the users of PHDs. However, compatibility and extensibility among manufacturers of PHDs have not been taken into account in most of the studies done on the development of PHDs because most of them have been supported by individual medical organizations. Therefore, the aim of this study was to design and develop a u-Health system for smart phones with the ISO/IEEE 11073 PHD standards, which were able to provide medical services anytime and anywhere.

Probability-based spray and wait protocol in Delay Tolerant Networks

Delay Tolerant Networks (DTNs) are one of the most interesting evolutions of MANETs. In DTNs which can be characterized by intermittent connectivity, frequent end-to-end path disruption and topology changes, mobile nodes are enabled to communicate with each other even if a route connecting them never exists. When considering routing protocols of DTNs, a forwarding decision and the buffer management scheme are important to improve the opportunity of successful message delivery. In this paper, we propose improved spray and wait routing based on the delivery probability. The simulation results show that the proposed method provides a better delivery ratio and lower communication overhead compared to existing schemes such as epidemic, spray and wait, and PRoPHET routing protocols.

Robust broadcast scheme regardless of vehicle distribution in vehicular ad hoc networks

In vehicular ad hoc networks (VANETs), the efficient and reliable dissemination of emergency messages in a highly mobile environment under a dense or sparse network is a significant challenge. This paper proposes a robust broadcast scheme for VANETs, called the virtual slotted p-persistence scheme, which operates efficiently regardless of the vehicle density and distribution. Via the exchange of hello messages, each vehicle maintains position information on neighbor vehicles in a neighbor table. When a vehicle receives an emergency message, it determines its vehicle group, called a virtual slot, based on the position information in its neighbor table. The proposed scheme guarantees that the vehicles in the farthest group from the broadcaster probabilistically rebroadcast the message first. Simulation results demonstrate that the proposed scheme outperforms the slotted p-persistence scheme in terms of the end-to-end delay, collision ratio, and network overhead, regardless of the vehicle density and distribution.

Neighbor information-based broadcast scheme for VANET

This paper proposes an efficient broadcast scheme based on a neighbor table to mitigate broadcast storms and to reduce the end-to-end delay. To alleviate a broadcast storm in a VANET, it is ideal that the rebroadcasting is performed by the vehicle furthest away from the broadcaster. Thereby the proposed scheme selects the furthest rebroadcasting vehicle based on neighbor tables. Simulation results demonstrate that the proposed scheme outperforms exiting schemes in terms of the end-to-end delay and collision ratio.

Design and Development of Personal Healthcare System Based on IEEE 11073/HL7 Standards Using Smartphone

The increased life expectancy of human due to the advance of medical techniques has led to many social problems such as rapidly aging populations, increased medical expenses and a lack of medical specialists. Thus, studies on improving the quality of life with the least amount of expense have been going on by incorporating advanced technologies, especially for Personal Health Devices (PHDs), into the medical service market. However, compatibility and extensibility among manufacturers of PHDs have not been taken into account in most of the researches done on the development of PHDs because most of them have been supported by individual medical organizations. The interoperability among medical organizations can not be guaranteed because each medical organization uses different format of the messages. Therefore, in this paper, an expansion module that can enable commercially-available non-standard PHDs to support the IEEE 11073, and a smart-phone-based manager that can support easy and comprehensive management on receiving and transmitting the collected data from each PHD using IEEE 11073 standard were developed. In addition, a u-health system that can transmit the data collected in the manager using the standard data format HL 7 to medical center for real-time medical service from every medical institutions that support this standard was designed and developed.

Multi-drone control and network self-recovery for flying Ad Hoc Networks

Drones can play important roles in various applications, such as search and rescue, situation awareness in natural disasters, environmental monitoring, and perimeter surveillance. Using a group of small drones has many advantages compared with developing and operating one large drone. In this paper, we propose a multi-drone real-time control scheme based on the Flying Ad-Hoc Network (FANET) for controlling drones that fall outside the communication range of the ground control system. We also propose a fast recovery scheme with neighbor location information in highly dynamic networks. We verified the operation of the proposed schemes using a FANET test bed implementation.

Handover decision algorithm based on available data volume in hierarchical macro/femto-cell networks

Hierarchical macro/femto-cell networks are considered a promising technology to increase overall network coverage and bandwidth at a relatively low cost. In these emerging networks, a large number of femtocells are deployed within a macrocell. When a macrocell includes many femtocells, the number of handovers greatly increases because handover from the macrocell to the femtocell is executed frequently. However, frequent handovers increase overhead due to handover management as well as latency due to handover interruption. In this paper, we propose an efficient handover decision algorithm based on available data volume to reduce the unnecessary handovers and increase the throughput. The simulation results show that the proposed algorithm effectively reduces the number of unnecessary handovers while improving the throughput compared to a conventional RSS based algorithm.

Enhanced PRoPHET routing protocol that considers contact duration in DTNs

PRoPHET is a probabilistic routing protocol for Delay Tolerant Networks (DTNs). In PRoPHET, the delivery probability is calculated based on the history of encounters and transitivity. However, if two nodes meet frequently during a short time interval, the delivery probability between these nodes increases rapidly. To solve this problem, PRoPHETv2 uses the inter-meeting time. Yet, the contact duration is still not considered. Therefore, this paper proposes an enhanced PRoPHETv2 routing protocol that considers the contact duration. Simulation results show that the proposed scheme outperforms PRoPHETv2 in terms of the delivery ratio and overhead ratio.

ACK-based broadcast protocol for vehicular ad hoc networks

This paper proposes a new vehicular broadcast protocol that can operate in a dense as well as in sparse highway traffic scenarios. ACK-CAST is a distributed multihop broadcast protocol that relies on acknowledgment messages from one-hop neighbors to select next rebroadcasting vehicle in VANETs. The performance of the proposed scheme was compared with SERVUS. Simulation results demonstrate that the proposed scheme performs better in terms of efficiency, reliability and scalability.

Beacon-less broadcast protocol for Vehicular Ad hoc Networks

This paper proposes a new vehicular broadcast protocol that can operate in dense as well as in sparse highway traffic scenarios. BL-CAST is a low overhead multi-hop broadcast protocol that does not rely on periodic exchange of hello messages. The performance of the proposed scheme was compared with DV-CAST. Simulation results showed that the performance of the proposed BL-CAST protocol is better than DV-CAST in terms of end-to-end packet delay and packet delivery ratio.