• Journal of Internet Computing and Services
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• v.18 no.6
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• pp.75-84
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• 2017

As there has been growing interests in PHR-based personalized health management project, various institutions recently explore safe methods of recording personal medical and health information. In particular, innovative medical solution can be realized when medical researchers and medical service institutes can generally get access to patient data. As EMR data is extremely sensitive, there has been no progress in clinical information exchange. Moreover, patients cannot get access to their own health data and exchange it with researchers or service institutions. It can be operated in terms of technology, yet policy environment are affected by state laws as well as Privacy and Security Policy. Blockchain technology-independent, in transaction, and under test-is introduced in the medical industry in order to settle these problems. In other words, medical organizations can grant preliminary approval on patient information exchange by using the safely encrypted and distributed Blockchain ledger and can be managed independently and completely by individuals. More apparently, medical researchers can gain access to information, thereby contributing to the scientific advance in rare diseases or minor groups in the world. In this paper, we focused on how to manage personal medical information and its protective use and proposes medical treatment exchange system for patients based on a permissioned Blockchain network for the safe PHR operation. Trusted Model for Sharing Medical Data (TMSMD), that is proposed model, is based on exchanging information as patients rely on hospitals as well as among hospitals. And introduce medical treatment exchange system for patients based on a permissioned Blockchain network. This system is a model that encrypts and records patients' medical information by using this permissioned Blockchain and further enhances the security due to its restricted counterfeit. This provides service to share medical information uploaded on the permissioned Blockchain to approved users through role-based access control. In addition, this paper presents methods with smart contracts if medical institutions request patient information complying with domestic laws by using the distributed Blockchain ledger and eventually granting preliminary approval for sharing information. This service will provide an independent information transaction and the Blockchain technology under test will be adopted in the medical industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.11
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• pp.652-659
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• 2014

In this paper, we propose an access point selection method for mobile users in LTE-femtocell system. In wireless communication system, users want to receive good data service. In LTE-femtocell system, if users move a little, users can experience different data service. The proposed access point selection method help that if users move a little, users obtain the high capacity and that user selects access point that other user have not selected much and so obtains higher data service. We simulated in order to prove performance of the proposed access point selection metod. Simulation results show that in a situation that users are concentrated in order to obtain better data service users are seen scattered look. As a result, we confirm that the proposed access point selection method provides good data service to users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.95-98
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• 2006

Data collected by sensors in field are transmitted to the base station gathering all of data. Because sensors have to gather data in surroundings and periodically transmit data to the base station, it makes energy consumed much. In this paper, we propose the scheme that is to avoid traffic congestion with achievement of energy efficiency, so collected data is transmitted efficiently. This is to adjust transmission rate differently in case of increasing or decreasing traffic and minimize the energy consumption with setting ideal options up basic CSMA(Carrier Sense Multiple Access) protocol in each sensor. Through the simulation, we find the ideal CSMA options and apply the proposed scheme of traffic control mechanism to them, then show energy efficiency and effective traffic control mechanism.

• Journal of KIISE:Databases
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• v.34 no.1
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• pp.1-17
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• 2007

As XML is becoming a de facto standard for distribution and sharing of information, the need for an efficient yet secure access of XML data has become very important. To enforce the fine-level granularity requirement, authorization models for regulating access to XML documents use XPath which is a standard for specifying parts of XML data and a suitable language for both query processing. An access control environment for XML documents and some techniques to deal with authorization priorities and conflict resolution issues are proposed. Despite this, relatively little work has been done to enforce access controls particularly for XML databases in the case of query access. Developing an efficient mechanism for XML databases to control query-based access is therefore the central theme of this paper. This work is a proposal for an efficient yet secure XML access control system. The basic idea utilized is that a user query interaction with only necessary access control rules is modified to an alternative form which is guaranteed to have no access violations using tree-aware metadata of XML schemes and set operators supported by XPath 2.0. The scheme can be applied to any XML database management system and has several advantages over other suggested schemes. These include implementation easiness, small execution time overhead, fine-grained controls, and safe and correct query modification. The experimental results clearly demonstrate the efficiency of the approach.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.1-7
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• 1992

This paper proposes reservation-based multiple access with variable frame length (RMAV) which is a new multiple access scheme for indoor and outdoor wireless data communications. RMAV is based on the slot reservation scheme and adopts a frame structure with variable frame length. The frame length increases as the number of active terminals and/or the system load increases. As a result, RMAV is adapted to the changes in the traffic pattern, and it offers short delay in light load conditions and high throughput in heavy load conditions. The performance of RMAV is evaluated by simulations. In addition, it is compared with the performance of PRMA(packet reservation multiple access).

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.117-122
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• 2012

We propose a hybrid multiple access (HMA) for uplink orthogonal frequency division multiple access (OFDMA) systems, which combines two resource sharing schemes: a scheduling-based resource allocation (SBRA) scheme and a contentionbased resource allocation (CBRA) scheme. The SBRA scheme is appropriate for non-real time high data rate traffic, and, CBRA is appropriate for near-real time low/medium data rate traffic. Thus, the proposed HMA scheme supports various types of traffic. As a CBRA scheme, our proposed random frequency hopping (RFH)-OFDMA scheme was presented. Simulation results show that the proposed HMA yields the best performance among various resource allocation schemes for uplink OFDMA systems.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.15-22
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• 2013

In oceanic flight routes, HF radio and satellite data links have weather restrictions, long propagation delay and low data throughput. In this paper, we propose oceanic aeronautical communications scheme in the VHF band based on ad-hoc communication. The proposed scheme organizes autonomously a multi-hop network that is divided into multiple local network using aircraft to fly long-distance communication and supports a hybrid type of multiple access, which consists of random access and TDMA (Time Division Multiple Access) scheme. In addition, several algorithms to apply spatial reuse of transmission to multi-hop long range communication environments have been proposed. The proposed system proves performance improvement on delay time as an effective solution to communicate end-to-end on the oceanic flight routes and strengthens the reliability of oceanic aeronautical communication.

• Journal of the Korea Society of Computer and Information
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• v.12 no.5
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• pp.225-233
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• 2007

This paper uses the taxonomy of 3 metadata schema(extraction metadata, warehouse, metadata, and user access metadata) to investigate how to manage metadata and what metadata to manage in data warehouse. In particular, this paper focuses on two kinds of metadata(warehouse metadata and user access metadata) and studies a case about metadata management in a real business world

• Journal of KIISE:Databases
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• v.36 no.1
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• pp.44-49
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• 2009

In recent years, with the development of portable terminals, various searching services on large data have been provided in portable terminals. In order to search large data, most applications for information retrieval use indexes such as B-trees or R-trees. However, only a small portion of the data set is accessed by users, and the access frequencies of each data are not uniform. The existing indexes such as B-trees or R-trees do not consider the properties of the skewed access patterns. And a cache stores the frequently accessed data for fast access in memory. But the size of memory used in the cache is restricted. In this paper, we propose a new index based on disk, called J-tree, which considers user's search patterns. The proposed index is a balanced tree which guarantees uniform searching time on all data. It also supports fast searching time on the frequently accessed data. Our experiments show the effectiveness of our proposed index under various settings.

• Journal of KIISE:Databases
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• v.35 no.6
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• pp.518-532
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• 2008

Broadcast scheme has been widely researched for efficient data delivery in the mobile environment because the downlink capacity of a mobile client is much greater than the uplink capacity, and the power of a mobile client is limited. In the proposed scheme, the index lets the client know when data items would be broadcasted and enables the client to minimize the tuning time and power consumption. Single channel index schemes are fit to flat broadcast that performs well when all the broadcasted data items are accessed with the same probability whereas the multi-disk broadcast scheme is proper when the data access distribution is skewed. The existing index schemes, however, cannot work on the Multi-disk broadcast scheme because they cannot point the replicating data items in a broadcast cycle. This paper proposes a Multi-disk Exponential Index (MDEI) which is a single channel index scheme fit to Multi-disk broadcast scheme. Because MDEI scheme organizes a separate index for each disk, it functions with multi-disk broadcast, resulting in a greater reduction of average access latency than that of other flat-broadcast index schemes when the data access distribution is skewed. The performance evaluation showed that MDEI has a good performance when data access distribution is skewed. MDEI has short average access latency and not much average tuning time when the data access distribution is skewed.