• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.847-854
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• 2005

Many of scheduling algorithms that provide a pre-defined bandwidth to a traffic flow fall into a category of Latency-rate (LR) server, the delay of whose network can be simply calculated by adding up individual 'latencies' of each LR servers. Deficit Round Robin (DRR) is one of such LR servers and the simplest one to implement, so that it is adopted in many real systems. In this research we suggest an improved version of DRR, the DRR with Instant Service (DRR-IS), and analyze it. We have proved that the DRR-IS is still an LR sewer and have obtained its latency. The DRR-IS, compared with DRR, turns out to have the same complexity while provide about $30\%$ better latency.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.641-648
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• 2003

In this paper, we propose a general analysis tool that derives guaranteed delay bounds for real-time sessions when those sessions pass through heterogeneous schedulers in general packet networks. This tool characterizes each different scheduler by a homogeneous service curve server. We show that service curve servers can characterize a strictly larger class of schedulers than LR servers. That is, we can characterize not only all LR servers but also RC-EDF and SC scheduler by service curve servers. Even with such advantage over LR servers, service curve servers provide accurate analysis results. We prove mathematically that if we analyze a network that can be analyzed by both LR servers and service curve servers,,both cases yield the same delay bound.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.75-90
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• 2004

At Asiacrypt 2003, Shin et al., have proposed a new class for Authenticated Key Establishment (AKE) protocol named Leakage-Resilient AKE ${(LR-AKE)}^{[1]}$. The authenticity of LR-AKE is based on a user's password and his/her stored secrets in both client side and server side. In their LR-AKE protocol, no TRM(Tamper Resistant Modules) is required and leakage of the stored secrets from $.$my side does not reveal my critical information on the password. This property is useful when the following situation is considered :(1) Stored secrets may leak out ;(2) A user communicates with a lot of servers ;(3) A user remembers only one password. The other AKE protocols, such as SSL/TLS and SSH (based or PKI), Password-Authenticated Key Exchange (PAKE) and Threshold-PAKE (T-PAKE), do not satisfy that property under the above-mentioned situation since their stored secrets (or, verification data on password) in either the client or the servers contain enough information to succeed in retrieving the relatively short password with off-line exhaustive search. As of now, the LR-AKE protocol is the currently horn solution. In this paper, we prove its security of the LR-AKE protocol in the standard model. Our security analysis shows that the LR-AKE Protocol is provably secure under the assumptions that DDH (Decisional Diffie-Hellman) problem is hard and MACs are selectively unforgeable against partially chosen message attacks (which is a weaker notion than being existentially unforgeable against chosen message attacks).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.53-60
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• 2007

We investigate the end-to-end delay bounds in large scale networks with Differentiated services (DiffServ) architecture. It is generally understood that networks with DiffServ architectures, where packets are treated according to the class they belong, can guarantee the end-to-end delay for packets of the highest priority class, only in lightly utilized cases. We focus on tree networks, which are defined to be acyclic connected graphs. We obtain a closed formula for delay bounds for such networks. We show that, in tree networks, the delay bounds exist regardless of the level of network utilization. These bounds are quadratically proportional to the maximum hop counts in heavily utilized networks; and are linearly proportional to the maximum hop counts in lightly utilized networks. Considering that tree networks, especially the Ethernet networks are being accepted more and more for access networks as well as provider networks, we argue that based on these delay bounds DiffServ architecture is able to support real time applications even for a large network. Throughout the paper we use Latency-Rate (LR) server model, with which it has proven that FIFO and Strict Priority are LR servers to each flows in certain conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1097-1102
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• 2008

An effective method for calculating delay bounds of flows through flow aggregations and deaggregations is given. Based on this calculation, it is suggested a simple criteria for flow aggregation whether the aggregation will induce an increased delay bound. The criteria is evaluated in a few realistic scenarios.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.121-128
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• 2021

In order to design a real time big data collection and analysis system of manufacturing data in a smart factory, it is important to establish an appropriate wired/wireless communication system and protocol. This paper introduces the latest communication protocol, OPC-UA (Open Platform Communication Unified Architecture) based client/server function, applied user interface technology to configure a network for real-time data collection through IoT Integration. Then, Database is designed in MES (Manufacturing Execution System) based on the analysis table that reflects the user's requirements among the data extracted from the new cutting process automation process, bush inner diameter indentation measurement system and tool monitoring/inspection system. In summary, big data analysis system introduced in this paper performs SPC (statistical Process Control) analysis and visualization analysis with interface of OPC-UA-based wired/wireless communication. Through AI learning modeling with XGBoost (eXtream Gradient Boosting) and LR (Linear Regression) algorithm, quality and visualization analysis is carried out the storage and connection to the cloud.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1141-1149
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• 2010

Next Generation Networks (NGN) is defined as IP-based networks with multi-services and with multi-access networks. A variety of services and access technologies are co-existed within NGN. Therefore there are numerous transport technologies such as Differentiated Services (DiffServ), Multi-protocol Label Switching (MPLS), and the combined transport technologies. In such an environment, flows are aggregated and de-aggregated multiple times in their end-to-end paths. In this research, a method for calculating end-to-end delay bound for such a flow, provided that the information exchanged among networks regarding flow aggregates, especially the maximum burst size of a flow aggregate entering a network. We suggest an admission control mechanism that can decide whether the requested performance for a flow can be met. We further verify the suggested calculation and admission algorithm with a few realistic scenarios.