• Journal of the Korean Mathematical Society
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• v.50 no.5
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• pp.1067-1082
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• 2013

In this paper, we will find some recurrence relations of classical multiple OPS between the same family with different parameters using the generating functions, which are useful to find structure relations and their connection coefficients. In particular, the differential-difference equations of Jacobi-Pineiro polynomials and multiple Bessel polynomials are given.

• Journal of the Korean Statistical Society
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• v.31 no.2
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• pp.163-175
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• 2002

An extended version of the minimax eccentricity factor estimation for multiple set case is proposed. In addition, two more simple methods for multiple set factor analysis exploiting the concept of generalized canonical correlation analysis is suggested. Finally, a certain connection between the generalized canonical correlation analysis and the multiple set factor analysis is derived which helps us clarify the relationship.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.45-50
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• 2011

In this paper, the encoding time delay of FH/TDD(Frequency Hopping/Time Division Duplex) based Motion JPEG image compression CODEC is analyzed for radio video transmissions of multi-camera systems in a vehicle. And, Synchronized connection of minimum channel collision is designed with synchronized shift and access according to channel status for Motion JPEG based FH/TDD multiple access.

• Korean Journal of Artificial Intelligence
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• v.11 no.2
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• pp.1-6
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• 2023

This paper presents a comprehensive scheme for assessing the importance of multiple microgrids (MGs) network that includes distributed energy resources (DERs), renewable energy systems (RESs), and energy storage system (ESS) facilities. Due to the uncertainty of severe weather, large-scale cascading failures are inevitable in energy networks. making the assessment of the structural vulnerability of the energy network an attractive research theme. This attention has led to the identification of the importance of measuring energy nodes. In multiple MG networks, the energy nodes are regarded as one MG. This paper presents a modified PageRank algorithm to assess the importance of MGs that include multiple DERs and ESS. With the importance rank order list of the multiple MG networks, the core MG (or node) of power production and consumption can be identified. Identifying such an MG is useful in preventing cascading failures by distributing the concentration on the core node, while increasing the effective link connection of the energy flow and energy trade. This scheme can be applied to identify the most profitable MG in the energy trade market so that the deployment operation of the MG connection can be decided to increase the effectiveness of energy usages. By identifying the important MG nodes in the network, it can help improve the resilience and robustness of the power grid system against large-scale cascading failures and other unexpected events. The proposed algorithm can point out which MG node is important in the MGs power grid network and thus, it could prevent the cascading failure by distributing the important MG node's role to other MG nodes.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.3-11
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• 2017

Research and development are being conducted to apply low-power Bluetooth (BLE) technology to IoT (Internet of Things) applications. The characteristic of this application environment is that many piconets can operate in the same space. Therefore, interference between homogeneous networks is likely to occur. In the BLE data channel, adaptive frequency hopping (AFH) scheme is used among the 37 frequency channels, and the master and the slave communicate while changing the carrier frequency. If there are multiple BLE piconets in the same space, there is a risk of frequency collision and packet errors will occur. In this paper, we analyze the packet collision probability due to cochannel interference in multiple asynchronous BLE piconet environments. Specifically, we analyzed packet collision probability according to the number of concurrently operating BLE piconets with the ratio of connection interval to connection event length as the main parameters. The analysis result can be used to set connection event related parameters for a desired packet collision probability according to the number of users having BLE devices in a given space.

• Journal of Communications and Networks
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• v.10 no.4
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• pp.455-464
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• 2008

To provide network services consistently under various network failures, enterprise networks increasingly utilize path diversity through multi-homing. As a result, multi-homed non-transit autonomous systems become to surpass single-homed networks in number. In this paper, we address an inevitable problem that occurs when networks with multiple entry points deploy firewalls in their borders. The majority of today's firewalls use stateful inspection that exploits connection state for fine-grained control. However, stateful inspection has a topological restriction such that outgoing and incoming traffic of a connection should pass through a single firewall to execute desired packet filtering operation. Multi-homed networking environments suffer from this restriction and BGP policies provide only coarse control over communication paths. Due to these features and the characteristics of datagram routing, there exists a real possibility of asymmetric routing. This mismatch between the exit and entry firewalls for a connection causes connection establishment failures. In this paper, we formulate this phenomenon into a state-sharing problem among multiple fire walls under asymmetric routing condition. To solve this problem, we propose a stateful inspection protocol that requires very low processing and messaging overhead. Our protocol consists of the following two phases: 1) Generation of a TCP SYN cookie marked with the firewall identification number upon a SYN packet arrival, and 2) state sharing triggered by a SYN/ACK packet arrival in the absence of the trail of its initial SYN packet. We demonstrate that our protocol is scalable, robust, and simple enough to be deployed for high speed networks. It also transparently works under any client-server configurations. Last but not least, we present experimental results through a prototype implementation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.987-995
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• 1999

The handoff is a distinctive characteristic of the mobile networks. In the CDMA systems, if base stations support multiple Frequency Assignment (FA), they provide both soft handoff and hard handoff. Under the CDMA environments, the soft handoff guarantees the favorable service quality and the continuity of call connection without interruption, and increases the service capacity of the base stations. This paper proposes call connection control schemes with handoff queue for supporting efficient handoff processing. The proposed schemes are divided into two categories: single handoff queue scheme and multiple handoff queue scheme. We analyze the performance of the proposed call connection control schemes using numerical analysis. From the analysis results, we can say that it is more desirable to avoid hard handoff as long as handoff queues are used. When a single handoff queue used, adaptive scheme that properly mixes avoidable and avoidable hard handoff method under the given traffic condition is more desirable. In case that multiple handoff queues are used, the suitable trade-off needs to be developed between handoff blocking probability and hard handoff probability to guarantee a given blocking probability threshold.

• Education of Primary School Mathematics
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• v.15 no.3
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• pp.201-218
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• 2012

In this study, the following topics were investigated targeting elementary school students: Schema formed through precise notion of cognitive and the connection of the concepts when studying common divisor, common multiple, and the lowest common multiple, configuration ability and problem solving of the students when learning using a modified schema, how the schema of the student to advance to a higher level, and how the deformation of the schema is carried out student's configuration of concept and problem solving ability. As a result, it was found out that cognition about precise concept, schema and the modified schema are important factors when a primary concept was developed into a secondary concept, and play important roles when the connection and the formation of the modified schema created by cognition about the precise primary concept rather than by the formation of the secondary concept (formation of the secondary schema) created by the connection between the primary concept.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.343-358
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• 2008

Piles of a bridge pier are connected with a column through a pile cap(footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. This difference causes a change of the design method. Connection methods between pile heads and the pile cap are divided into two groups ; rigid connections and hinge connections. KHBDC(Korea Highway Bridge Design Code) has specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However some specifications prescribe that conservative results through investigations for both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which have very good quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) are unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the very large diameter drilled shaft and the pile cap for Incheon Bridge which will the longest bridge in Korea were investigated through the full modeling for rigid connection conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2112-2115
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• 2003

In this paper, we describe a SSAS (stepping stones attack simulator) that is automatic tool for testing and evaluation in TCP connection traceback system. The SSAS can pass multiple hosts that are included with hacker, middle-path hosts and victim’s system. And SSAS can also attack through commands to exploit the victim’s system. Usually, hackers do not expose their real attack positions through compromising the middle-path hosts like stepping-stones. Namely, hackers perform the stepping stones attacks in Internet. The SSAS can be utilized by developments and tests of the various countermeasure techniques of hacking. Specially, in this paper, it is used to test the performance of TCP connection traceback system.