• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2382-2392
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• 2014

In this paper, a new data frame structure for wavelength routing in optical ring access network(ORAN) is designed and the functions of each field in the frame are defined. In addition, the IP packet transmission to the network layer corresponding to the newly proposed structure of the protocol stack is newly presented. Tha data transmission protocol design techniques of ORAN was proposed. IP packet and broadcasting packet transmission within the sub-network, and the IP packet transmission to other sub-network was shown through the process illustration. In the process, the encapsulation and framing process of the wavelength information to routing has been described in detail. And each step takes place in a packet transfer process is demonstrated. A ring type optical access network protocol is not yet research field. ORAN data transfer protocol to send/receive module structure of a subscriber node and a control node of the two rings which analyzed the results are shown. The high-speed Internet solution is proposed that by using wavelength routing the packet transport protocol for ORAN is designed.

• The KIPS Transactions:PartD
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• v.15D no.4
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• pp.441-450
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• 2008

Recently, access control on form-based web information systems has become one of the useful methods for implementing client systems in a service-oriented architecture. In particular, XForms language is being adopted in many systems as a description language for XML-based user interfaces and server interactions. In this paper, we propose an efficient algorithm for the evaluation of XPath-based access rules for XForms pages. In this model, an XForms page is a sequence of queries and the client system performs user interface realization along with XPath rule evaluations. XPath rules have instance-dependent predicates, which for the most part are shared between rules. For the efficient evaluation of shared predicate expressions in access control rules, we proposed a predicate graph model that reuses the previously evaluated results for the same context node. This approach guarantees that each predicate expression is evaluated for the relevant xml node only once.

• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.2
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• pp.87-96
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• 2019

Low power issue is one of the most critical problems in the Internet of Things (IoT), which are powered by battery. To solve this problem, various approaches have been presented so far. In this paper, we propose a method to reduce the power consumption by reducing the numbers of accesses into the flash memory consuming a large amount of power for on-chip software execution. Our approach is based on using cooperative logging structure to distribute the sampling overhead in single sensor node to adjacent nodes in case of rare-event applications. The proposed algorithm to identify event occurrence is newly introduced with negative feedback method by observing difference between past data and recent data coming from the sensor. When an event with need of flash access is determined, the proposed approach only allows access to write the sampled data in flash memory. The proposed event detection algorithm (EDA) result in 30% reduction of power consumption compared to the conventional flash write scheme for all cases of event. The sampled data from the sensor is first traced into the random access memory (RAM), and write access to the flash memory is delayed until the page buffer of the on-chip flash memory controller in the micro controller unit (MCU) is full of the numbers of the traced data, thereby reducing the frequency of accessing flash memory. This technique additionally reduces power consumption by 40% compared to flash-write all data. By sharing the sampling information via LoRa channel, the overhead in sampling data is distributed, to reduce the sampling load on each node, so that the 66% reduction of total power consumption is achieved in several IoT edge nodes by removing the sampling operation of duplicated data.

• Journal of Gastric Cancer
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• v.11 no.1
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• pp.1-6
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• 2011

Gastric cancer is the most common malignancy and the incidence is steadily increasing in Korea. The principal treatment modality for gastric cancer is surgical extirpation of tumor along with draining lymph nodes. Gastrectomy with D2 lymph node dissection has been well established as a standard of surgery and improved the survival of gastric cancer patients. Recently, technological advances are drastically reshaping the landscape of surgical treatment of gastric cancer. One of the most notable trends is that minimal access surgery becomes dominating the treatment of early stage diseases. For advanced diseases, the standard access surgery is considered a reference treatment. Although there is a pilot study underway to evaluate the feasibility of the application of minimal access surgery to advanced gastric cancer (AGC), the evidence for oncological safety is not yet provided sufficiently. Based on the recent randomized controlled trials, the extent of surgery for AGC has re-defined as para-aortic lymph node dissection dose not add any survival benefit while increasing surgery-related morbidities. In addition, it is now accepted as a standard operation omitting unnecessary procedures such as splenectomy and/or distal pancreatectomy for prophylactic lymph node dissection. Conceptual and technical innovation has contributed to decreasing morbidity and mortality without impairing oncological safety. All these recent advances in the field of gastric cancer surgery would be concluded in maximizing therapeutic index for gastric cancer while improving quality of life.

• The Journal of the Korea Contents Association
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• v.11 no.9
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• pp.17-25
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• 2011

The wireless mesh networks are recently getting much attention for commercial applications. In such networks, the service should be uninterrupted when roaming from one domain to another while the authentication for a secure access should be maintained. The challenge is to consider the authentic coordination between the home domain and foreign domains and the maintenance of local authenticity between foreign domains. In this paper, a novel authentication method is presented so that a mobile mesh node can be effectively authenticated and obtain an secure connection in foreign domains. In the proposed method, the authentication process does not rely on an end-to-end connection between the foreign domain and the home domain. Even without a connectivity to the home domain, the foreign domain can provide an effective authentication of a mesh node by consulting one of the neighboring foreign domains that has been visited by the mobile mesh node. In order to verify the performance of our proposed method, a qualitative analysis has been performed and compared to those of conventional methods. The results show that our method is superior to the conventional ones in terms of authentication response time and authentication service robustness.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.190-197
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• 2010

The ACR (Access Control Router) of WiBro processes location registration of the Correspondent Node and Home Agent as the Correspondent Node moves between ACRs. Therefore, the location update cost is low compared with MIPv6. However, all packets which are sent and received are sent through the ACR, so as the number of mobile nodes that are managed by the ACR increases, the cost of packet delivery also increases. Therefore, the communication state of the ACR domain remains smooth when the ACR which manages the mobile node in the ACR domain has good performance. However, network delays occur unless the ACR performs well, so the role of the ACR is important. In this paper, we analysis performance of the ACR for efficient realization of the WiBro standard. By using the Deny Probability and the Total Profit of ACR performance and apply it to the Random Walk Mobility model as the mobility model.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.5
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• pp.371-379
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• 2009

Conventional sensor node operating systems do not support sensor abstraction for sensor applications. So, application programmers have to take charge of developing the hardware and the device drivers for the applications by themselves. In this paper, we present an as architecture to support sensor abstraction. The as provide not only application programmers with API library to access sensor devices, but also sensor developers with HAL library to access sensor hardware. This can reduce the development burden of application programmers significantly. In this paper, at first, we define the sensor HW interface to ease the attachment of sensors. Second, we describe the sensor access API for application programmers. Third, we define the HAL library for sensor device programmers to use. Finally, we show that the as can support sensor abstraction by illustrating the sample programs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2811-2817
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• 2010

In this paper we propose the QAC-MAC that supports Quality of Service(QoS) and saves energy resources of the sensor node, and hence prolonging the lifetime of the sensor network with multiple sink nodes. Generally, the nodes nearest to the sink node often experience heavy congestion since all data is forwarded toward the sink through those nodes. So this critically effects on the delay-constraint data traffics. QAC-MAC uses a hybrid mechanism that adapts scheduled scheme for medium access and scheduling and unscheduled scheme based on TDMA for no data collision transmission. Generally speaking, characteristics of the real-time traffic with higher priority tends to be bursty and has same destination. QAC-MAC adapts cross-layer concept to rearrange the data transmission order in each sensor node's queue, saves energy consumption by allowing few nodes in data transmission, and prolongs the network lifetime.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.6
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• pp.1599-1618
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• 2024

Access control has always been one of the effective methods to protect data security. However, in new computing environments such as big data, data resources have the characteristics of distributed cross-domain sharing, massive and dynamic. Traditional access control mechanisms are difficult to meet the security needs. This paper proposes CACM-MMSR to solve distributed cross-domain access control problem for massive resources. The method uses blockchain and smart contracts as a link between different security domains. A permission decision model migration method based on access control logs is designed. It can realize the migration of historical policy to solve the problems of access control heterogeneity among different security domains and the updating of the old and new policies in the same security domain. Meanwhile, a semantic reasoning-based permission decision method for unstructured text data is designed. It can achieve a flexible permission decision by similarity thresholding. Experimental results show that the proposed method can reduce the decision time cost of distributed access control to less than 28.7% of a single node. The permission decision model migration method has a high decision accuracy of 97.4%. The semantic reasoning-based permission decision method is optimal to other reference methods in vectorization and index time cost.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.249-257
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• 2003

Ring networks are very commonly exploited among local area and metropolitan area networks (LAN/MAN), whereas cells or small fixed-size packets are widely used in synchronized ring networks. In this paper, we present an analytical method for evaluating the delay-throughput performance of a MAC protocol with multiple self-tokens in a slotted ring network under uniform traffic. In our analysis, we introduce the stationary probability, which indicates the number of packets in a node. Also, it is assumed that each node has a sufficiently large amount of self-tokens, and a slotted ring has the symmetry. The analytical results with respect to delay-throughput performance have similar values to computer simulated ones. Furthermore, in order to achieve fair access under non-uniform traffic, we propose an adaptive MAC protocol, where the number of self-tokens in a node dynamically varies, based on the number of packets transmitted within a specified period. In the proposed protocol, when the number of packets transmitted by a node within a specified period is larger than a specified threshold, the node decreases the number of self-tokens in a per-node distributed method. That results in creating free slots in the ring, thus all nodes can obtain an equal opportunity to transmit into the ring. Performance results obtained by computer simulation show that our proposed protocol can maintain throughput fairness under non-uniform traffic.