• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제31권11B호
• /
• pp.953-959
• /
• 2006

This paper provides optimum TCP/IP packet size that maximizes the throughput efficiency of ATM layer as a function of TCP/IP packet length for several values of channel BER over wireless ATM LAN links applying data link error control schemes to reduce error problems encountered in using wireless links. For TCP/IP delay-insensitive traffc requiring reliable delivery, it is necessary to adopt data link layer ARQ protocol. So ARQ error control schemes considered in this paper include GBN ARQ, SR ARQ and type-I Hybrid ARQ, which ARQ is needed, but FEC can be used to reduce the number of retransmissions. Especially adaptive type-I Hybrid ARQ scheme is necessary for a variable channel condition to make the physical layer as SONET-like as possible.

• Journal of Korea Society of Digital Industry and Information Management
• /
• 제11권3호
• /
• pp.79-90
• /
• 2015

Multipath routing technique is recognized as one of the effective approaches to improve the reliability of data forwarding. However, the traditional multipath routing focuses only on how many paths are needed to ensure a desired reliability. For this purpose, the protocols construct additional paths and thus cause significant energy consumption. These problems have motivated the study for the energy-efficient and reliable data forwarding. Thus, this paper proposes an energy-efficient concurrent multipath routing protocol with a small number of paths based on interaction between paths. The interaction between paths helps to reinforce the multipath reliability by making efficient use of resources. The protocol selects several nodes located in the radio overlapped area between a pair of paths as bridge nodes for the path-interaction. In order to operate the bridge node efficiently, when the transmission failure has detected by overhearing at each path, it performs recovery transmission to recover the path failure. Simulation results show that proposed protocol is superior to the existing multipath protocols in terms of energy consumption and delivery reliability.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권3호
• /
• pp.1330-1347
• /
• 2018

Mobile Ad hoc Network (MANET) is a collection of nodes or communication devices that wish to communicate without any fixed infrastructure and predetermined organization of available links. The effort has been made by proposing a scheme to overcome the critical security issue in MANET. The insufficiency of security considerations in the design of Ad hoc On-Demand Distance Vector protocol makes it vulnerable to the threats of collaborative black hole attacks, where hacker nodes attack the data packets and drop them instead of forwarding. To secure mobile ad hoc networks from collaborative black hole attacks, we implement our scheme and considered sensor's energy as a key feature with a better packet delivery ratio, less delay time and high throughput. The proposed scheme has offered an improved solution to diminish collaborative black hole attacks with high performance and benchmark results as compared to the existing schemes EDRIAODV and DRIAODV respectively. This paper has shown that throughput and packet delivery ratio increase while the end to end delay decreases as compared to existing schemes. It also reduces the overall energy consumption and network traffic by maintaining accuracy and high detection rate which is more safe and reliable for future work.

• Journal of the Korea Society for Simulation
• /
• 제16권3호
• /
• pp.49-56
• /
• 2007

There are many application areas of wireless sensor networks, such as combat field surveillance, terrorist tracking and highway traffic monitoring. These applications collect sensed data from sensor nodes to monitor events in the territory of interest. One of the important issues in these applications is the existence of the radio-jamming zone between source nodes and the base station. Depending on the routing protocol the transmission of the sensed data may not be delivered to the base station. To solve this problem we propose a genetic algorithm based routing method for reliable transmission while considering the balanced energy depletion of the sensor nodes. The genetic algorithm finds an efficient routing path by considering the radio-jamming zone, energy consumption needed fur data transmission and average remaining energy level. The fitness function employed in genetic algorithm is implemented by applying the fuzzy logic. In simulation, our proposed method is compared with LEACH and Hierarchical PEGASIS. The simulation results show that the proposed method is efficient in both the energy consumption and success ratio of delivery.

• Water for future
• /
• 제26권3호
• /
• pp.63-74
• /
• 1993

The objectives of this paper were to apply the gross erosion and sediment delivery ration method for estimating sediment deposits at selected reservoirs of various sizes, and to define their trap efficiencies. Twenty reservoirs that have sediment survey data were selected and the annual average soil losses from subareas within each watershed were estimated using the Universal Soil Loss Equation (USLE). The gross erosion was defined fro the soil losses and estimated channel erosion. By applying the sediment delivery ratios that were defined from an empirical relationship with watershed areas, net incoming sediment yields at reservoirs were defined. Trap efficiencies were applied, sediment deposits estimated, and compared to the surveyed data. The results were in general agreement with the data. Trap efficiencies were also defined from the ratios of sediment deposits to incoming sediment yields. They were within 20% differences from Brune curve, which indicates that Brune curve may be applied for irrigation reservoirs. And an empirical relationship was proposed, that appeared more reliable for estimating trap efficiencies for typical irrigation reservoirs.

• YAKHAK HOEJI
• /
• 제57권5호
• /
• pp.362-368
• /
• 2013

High performance liquid chromatograph (HPLC) is the most frequently used analytical instrument in analytical laboratories for pharmaceutical analysis. In order to provide a high level of assurance for reliable data generated from the HPLC analysis, the performance qualification of the HPLC system is required. For this purpose, the performance of HPLC system should be regularly monitored by examining the key functions of the typical HPLC system (solvent delivery system, injector system, column oven, UV-VIS detector system). We have investigated the validation guidelines of the performance verification of these key modules for HPLC system. And we proposed and evaluated its validation guidelines and the related verification methods for pharmaceutical analysis that could be practically applied in Korea.

• Journal of information and communication convergence engineering
• /
• 제14권1호
• /
• pp.14-20
• /
• 2016

The AODV protocol uses many RREQ messages and one RREP message in the path-discovery process. This protocol has only one metric, the number of hops. Although it is simple, this protocol is not efficient. To avoid this problem, we propose a new AODV with two auxiliary metrics (AuM-2-AODV). The AuM-2-AODV protocol tries multiple route replies, which reduces the chance of path failure and helps the network obtain a better data rate. It has two auxiliary metrics, the remaining energy of its nodes and the number of HELLO messages received at the nodes. With these two metrics, the reliable path from the source node to the destination node will be chosen. In this paper, the performance of the AuM-2-AODV is evaluated using the NS-3 simulator. The performance results show that AuM-2-AODV provides greater throughput and packet delivery ratio by 20% and up to 50% and about 100% in some cases, respectively, than previous protocols.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권4호
• /
• pp.1223-1236
• /
• 2014

With the extension of wireless technology, vehicular ad hoc networks provide important services for the dissemination of general data and emergency warnings. However, since, the vehicle topology frequently changes from a dense to a sparse network depending on the speed of the moving vehicles and the time of day, vehicular ad hoc networks require a protocol that can facilitate the efficient and reliable dissemination of emergency messages in a highly mobile environment under dense or intermittent vehicular connectivity. Therefore, this paper proposes a new vehicular broadcast protocol, called BL-CAST, that can operate effectively in both dense and sparse network scenarios. As a low overhead multi-hop broadcast protocol, BL-CAST does not rely on the periodic exchange of beacons for updating location information. Instead, the location information of a vehicle is included in a broadcast message to identify the last rebroadcasting vehicle in an intermittently connected network. Simulation results show that BL-CAST outperforms the DV-CAST protocol in terms of the end-to-end delay, message delivery ratio and network overhead.

• Women's Health Nursing
• /
• 제12권3호
• /
• pp.204-209
• /
• 2006

Purpose: The Edinbergh Postnatal Depression Scale (EPDS) has seen widespread use in epidemiological and clinical studies. The objective of this research was to translate and to test the reliability and validity of the 10-item EDPS in Korea. Methods: Subjects were 145 women who were 6 to 10 weeks post delivery. To test reliability, the internal consistency was assessed by Cronbach's alpha coefficient. Validity testing was performed using convergent validity by Pearson's correlation. Data was gathered at 3 hospitals during Oct. 2005 after obtaining an informed consent. Result: The mean age of the subjects was 29.9 years. and the mean parity was 1.46 times. The mean EPDS score was 18.4. Reliability analysis showed a satisfactory result (Cronbach's alpha coefficient=.84). There were significant positive correlations between EPDS and Mills postnatal depression and anxiety check list scores as expected(r=.69, p<.001) and thus supported convergent validity. Conclusion: The study findings showed that the Korean version of the EPDS-10 is a reliable and valid instrument that can be used for measuring postnatal depression in Korea.

• Journal of Information Technology Services
• /
• 제9권2호
• /
• pp.179-192
• /
• 2010

In order to resolve the problems of traditional Enterprise Application Integration (EAI) for system integration and to establish flexible enterprise IT environments, Enterprise Service Bus(ESB) which have distributed architecture and support Service Oriented Architecture(SOA) has introduced. Particularly, JBI which developed by the Java Community Process is most widely used to implement ESB for advantages of Java technology. In ESB based on JBI, reliable message delivery is very important to ensure stability of services and systems because it is a message driven architecture. But, it is difficult to verify messages and trace messages when system fault or service error occurred because JBI specification is not enough to address them. In this paper we has proposed the Message Monitoring Framework for JBI-based ESBs which for using in monitoring messages efficiently. It provides foundations for gathering and tracing message-related information about component installation, message exchange, service deploy by using proxy-based change tracking and delegation mechanism for data processing. The proxy which used in our solutions collects data about message automatically when it changed, and the delegation mechanism provides users flexibility for data processing. Also, we describe the performance evaluation results of our solution which is acceptable. We expect to it enables users to ensure reliability and stability of the JBI-based ESB by systematic monitoring and managing messages being used to interact among components.