• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.5
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• pp.193-193
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• 2003

This Paper analyses several model-order reduction methods and then proposes an improved n model and a new delay calculation method to be used in analyzing RC-class interconnects, which does not involve moment calculation processes. The proposed delay calculation method has been derived by combining the unproved $\pi$ model, the concept of effective capacitance and Elmore delay. This method has an advantage in that it can be applied in the calculation of end-to-end delay as well as incremental delay.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.5
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• pp.193-200
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• 2003

This Paper analyses several model-order reduction methods and then proposes an improved n model and a new delay calculation method to be used in analyzing RC-class interconnects, which does not involve moment calculation processes. The proposed delay calculation method has been derived by combining the unproved $\pi$ model, the concept of effective capacitance and Elmore delay. This method has an advantage in that it can be applied in the calculation of end-to-end delay as well as incremental delay.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.3
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• pp.206-211
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• 2005

The device makers want to make higher density chips on the wafer through scale-down. The change of WSix/poly-Si gate film thickness is one of the key issues under 100 nm device structure. As a new device etching process is applied, end point detection(EPD) time delay was occurred in DPS+ poly chamber of Applied Materials. This is a barrier of device shrink because EPD time delay made physical damage on the surface of gate oxide. To investigate the EPD time delay, the experimental test combined with OES(Optical Emission Spectroscopy) and SEM(Scanning Electron Microscopy) was performed using patterned wafers. As a result, a EPD delay time is reduced by a new chamber seasoning and a new wavelength line through plasma scan. Applying a new wavelength of 252 nm makes it successful to call corrected EPD in WSix/poly-Si stack-down gate etching in the DPS+ poly chamber for the current and next generation devices.

• Journal of KIISE
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• v.42 no.10
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• pp.1268-1279
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• 2015

In order to manage a large number of devices connected to the Internet of Things (IoT), the Internet Engineering Task Force (IETF) proposed the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). The route of the RPL network is generated through the use of an Objective Function (OF) that is suitable for the service that is required for the IoT network. Since the route of the RPL network is conventionally simply chosen only by considering the link quality between the nodes, it is sensible to seek an OF that can also provide better Quality of Service (QoS). In previous studies, the end-to-end delay might possibly be sub-optimal because they only deal with problems related to the reduction of energy consumption and not to the link quality on the path to the sink node. In this study, we propose a scheme that reduces the end-to-end delay but also gives full consideration to both the quality on the entire route to the destination and to the expected lifetime of nodes with bottlenecks from heaped traffic. Weighting factors for the proposed scheme are chosen by experiments and the proposed scheme can reduce the end-to-end delay and the energy consumption of previous studies by 20.8% and 10.5%, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.5
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• pp.3-9
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• 2015

The wireless communication system adopts an appropriate retransmission scheme on each system protocol layer to improve reliability of data transmission. In each system protocol layer, the retransmission scheme operates in independently other layers and operates based on the parameters without reference to end-to-end performance of wireless communication system. For this reason, it is difficult to design the optimal system parameters that satisfy the QoS requirements for each service class. Thus, the performance analysis of wireless communication system is needed to design the optimal system parameters according to the end-to-end QoS requirements for each service class. In this paper, we derive the mathematical model to formulate the end-to-end performance of wireless communication system. We also evaluate the performance at the MAC and transport layers in terms of average spectral efficiency and average transmission delay. Based on the results of performance evaluations, we design the optimal system parameters according to the QoS requirements of service classes. From the results, the HARQ combined with AMC is appropriate for the delay-sensitive service and the ARQ combined with AMC is appropriate for a service that is insensitive to transmission delay. Also, the TCP can be applied for the delay-insensitive service only.

• International journal of advanced smart convergence
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• v.7 no.4
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• pp.19-26
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• 2018

One of the distinct features of Wireless Sensor Networks (WSNs) is duty cycling mechanism, which is used to conserve energy and extend the network lifetime. Large duty cycle interval introduces lower energy consumption, meanwhile longer end-to-end (E2E) delay. In this paper, we introduce an energy consumption minimization problem for duty-cycled WSNs. We have applied Q-learning algorithm to obtain the maximum duty cycle interval which supports various delay requirements and given Delay Success ratio (DSR) i.e. the required probability of packets arriving at the sink before given delay bound. Our approach only requires sink to compute Q-leaning which makes it practical to implement. Nodes in the different group have the different duty cycle interval in our proposed method and nodes don't need to know the information of the neighboring node. Performance metrics show that our proposed scheme outperforms existing algorithms in terms of energy efficiency while assuring the required delay bound and DSR.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.4
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• pp.625-634
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• 2014

Tactical networks is being operated in configuration that consisting of a variety of characteristics communication equipments and heterogeneous networks. In this configurations, end-to-end communication can be achieved using interworking gateway for converting the data format of the network and using encryption algorithm of the networks. The use of mechanism results in a problem that secure data cannot be transferred directly, reprocessing and processing delay of communication in heterogeneous tactical networks. That is, for encoding and decoding of data, the decryption of encrypted data and re-encryption processing must be required at the gateway between different networks. In this paper proposes to mechanism for end-to-end secure communication in heterogeneous tactical networks. Using the proposed method, end-to-end secure communication between heterogeneous tactical networks(PSTN-UHF networks) which removes the necessity of a gateway for converting data into data formats suitable for network to remove a transmission delay factor and enable real-time voice and data communication and achieve end-to-end security for heterogeneous tactical networks. we propose a novel mechanism for end-to-end secure communication over PSTN and UHF networks and evaluate against the performance of conventional mechanism. Our proposal is confirmed removal of security vulnerabilities, end-to-end secure communication in heterogeneous tactical networks.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.57-67
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• 1996

This paper aims to support delay-sensitive multimedia applications by suggesting a mechanism in which maintains almost constant end-to-end delay thus providing the optimum playout synchronization. For this task the sum of network delay and buffering delay is entiredly managed and to eliminate little delay fluctuations and instantaneous delays at a buffer and a network, a low pass filter is used. Furthermore the correction function, which is used for maintaining the buffering level ot a reference value, is a non-linear step function, unlike the existing linear and continuous function. it has a different step sizes adapting to a traffic characteristics of a network congestion. the proposed mechanism has been confirmed of it sefficiency through SLAM-II netowrk.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.597-606
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• 2001

In this paper, we propose the delay sensitive traffic and a high bandwidth QoS service in order to supply real-time traffic such as VoIP, multimedia service. We use IntServ over DiffServ network to supply end-to-end QoS service in the IETF. We define the proposed QoS services which are Best, Good, Default service. We analyze the performance using NS simulator with end to end QoS service in IntServ over DiffServ network. The proposed billing system uses the Accounting, Authentication, Authorization (AAA) functions of RADIUS protocol and proposes the dynamic pricing method according to network usage state using end-to-end QoS of IntServ over DiffServ network. In order to secure billing system, we design and implement audit trail system by the IEEE POSIX.1E standard.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.146-154
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• 2007

In this paper, we have presented a real-time transfer mechanism for the delay-sensitive data in WSNs (Wireless Sensor Networks). The existing methods for real-time data transfer select a path whose latency is shortest or the number of hops is least. Although the approaches of these methods are acceptable, they do not always work as efficiently as they can because they had no consideration for the link error rates. In the case of transmission failures on links, they can not guarantee the end-to-end real-time transfer due to retransmissions. Therefore, we have proposed an algorithm to select a real-time transfer path in consideration of the link error rates. Our mechanism estimates the 1-hop delay based on the link error rate between two neighboring nodes, which in turn enables the calculation of the expected end-to-end delay. A source node comes to choose a path with the shortest end-to-end delay as a real-time route, and sends data along the path chosen. We performed various experiments changing the link error rates and discovered that this proposed mechanism improves the speed of event-to-sink data transfer and reduces delay jitter. We also found that this mechanism prevents additional energy consumption and prolongs network lifetime, resulting from the elative reduction of transmission failures and retransmissions.