• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.7
• /
• pp.2225-2238
• /
• 2022

For advanced healthcare services, a variety of agents should maintain reliable connections with the manager and communicate personal health and medical information. The ISO/IEEE 11073 standards provide convenient interoperability and the optimized exchange protocol (OEP) supports efficient communication for devices. However, the standard does not specify secure communication, and sensitive personal information is easily exposed through attacks. Malicious attacks may lead to the worst results owing to service errors, service suspension, and deliberate delays. All possible attacks on the communication are analyzed in detail, and the damage is specifically identified. In this study, novel secure communication schemes over the 20601 OEP are proposed by introducing an authentication process while maintaining compatibility with existing devices. The agent performs a secure association with the manager for mutual authentication. However, communication with mutual authentication is not completely free from attacks. Message encryption schemes are proposed for concrete security. The authentication process and secure communication schemes between the secure registered agent (SRA) and the secure registered manager (SRM) are implemented and verified. The experimental analysis shows that the complexities of the SRA and SRM are not significantly different from those of the existing agent and manager.

• The Journal of Information Systems
• /
• v.6 no.1
• /
• pp.159-180
• /
• 1997

Database sharing system(DBSS) refers to a system for high performance transaction processing. In DBSS, the processing nodes are locally coupled via a high speed network and share a common database at the disk level. Each node has a local memory, a separate copy of operating system, and a DBMS. To reduce the number of disk accesses, the node caches database pages in its local memory buffer. However, since multiple nodes may be simultaneously cached a page, cache consistency must be ensured so that every node can always access the latest version of pages. In this paper, we propose efficient buffer invalidation schemes in DBSS, where the database is logically partitioned using primary copy authority to reduce locking overhead. The proposed schemes can improve performance by reducing the disk access overhead and the message overhead due to maintaining cache consistency. Furthermore, they can show good performance when database workloads are varied dynamically.

• Journal of Korean Institute of Industrial Engineers
• /
• v.14 no.1
• /
• pp.1-15
• /
• 1988

DS1 transmission systems use framing bit errors, bipolar violations and code-detected errors to estimate the bit error rate when determining errored and severely errored seconds. Using the coefficient of variation under the memoryless binary symmetric channel assumption, a basic framework to evaluate these estimation schemes is proposed to provide a practical guideline in determining errored and severely errored seconds which are fundamental in monitoring the real-ime error performance of DS1 transmission systems carrying live traffic. To evaluate the performance of the cyclic redundancy check code (CRC), a computer simulation model is used. Several drawbacks of the superframe format in association with real time error performance monitoring are discussed. A few recommendations are suggested in measuring errored and severely errored seconds, and determining service limit alarms through the use of the superframe format. Furthermore, we propose a new robust scheme for determining service limit alarms which take into consideration the limitations of some estimation schemes for the time interval of one second.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.09a
• /
• pp.747-748
• /
• 2005

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.09b
• /
• pp.995-996
• /
• 2005

• Proceedings of the Korea Contents Association Conference
• /
• 2006.11a
• /
• pp.61-64
• /
• 2006

As a demand of mobile network is increasing, mobile support protocols are suggested. Although HMIPv6 managing the micro mobility with MAP suggests a plan for an effectively mobile support, there has a problem of traffic concentrating. This paper propose efficient schemes of distributing the traffic concentrated on hierarchical Mobile IPv6. This proposed schemes, selecting MAP more than two, are divided by selected 'Active' and 'Passive' MAP. The proposed schemes change a state in MAP and define performance to distribute a load in MAP as the Load is occurred by traffic.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.2
• /
• pp.13-22
• /
• 2008

This study is to suggest a method of constructing Informatics textbook considering the cognitive development level of middle school learners. We developed 3 types of learning content models according to the educational objectives and activities of learners and then suggested the methods of constructing textbook. For this, we reviewed the related research results on the development characteristics and cognitive development theories of middle school students. Second, we drew instructional schemes from the pedagogic theories. Then, we suggested 3 models: 'Learning Centered on Concept'. 'Learning Centered on Investigation', and ' learning Centered on Actual Training'. We suggested construction schemes to each model and verified the adequacy using questionnaire to 30 teachers and received the positive responses from most teachers.

• Journal of Korea Water Resources Association
• /
• v.38 no.2
• /
• pp.155-166
• /
• 2005

Upwind schemes are very well adapted to the discontinuous flow and have become popular for applications Involving dam break flow, transcritical Slow, etc. However, upwind schemes have been applied mainly to the idealized problems not to the natural channels with irregular geometry so far because of the error due to source terms. In this paper, the new type of upwind discretization of source terms, which uses the normalized Jacobian to discretize the source terms, is proposed. As results of tests to flows with source terms by the upwind models, the method proposed in this paper is proved as efficient and accurate. This generalized method for differencing source terms is simple and might beapplicable to diverse type of flux upwind discretization scheme in finite difference method.

• Journal of Korea Port Economic Association
• /
• v.27 no.4
• /
• pp.219-235
• /
• 2011

Today FTAs(Free Trade Agreements) are revving up among countries in the course of glocalization. Dubai, Pudong of Shanghai, Binhai shinku of Tianjin are actively pursuing Free Zones, and Saemangeum District in Korea is under development as growth base in North East Asia. This study aims to present the proper development scale and other development schemes for Samangeum Newport. In conclusion, following several schemes are required; firstly more sophisticated forecasting of demand and supplementation for Saemangeum Newport, secondly development of dedicated container terminals and dedicated food terminals, and finally cruise terminal for the tourist activation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.1A
• /
• pp.101-108
• /
• 2007

There nay be collisions among beacons from several full function devices in IEEE 802.15.4 sensor networks. These collision of beacons may cause devices to lose time synchronization, and thus be unable to association. To solve this problem, the IEEE 802.15.4b defines a new Post Beacon Period(PBP), but it does not still alleviate the beacon collision problem. In this paper, we propose two automatic beacon alignment schemes that a node itself can decide its beacon start time using its short address that has been assigned during association. We also simulate and investigate our proposed automatic beacon collision avoidance schemes using NS-2 simulator.