• KIPS Transactions on Software and Data Engineering
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• 제7권2호
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• pp.51-62
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• 2018

High utility sequential pattern (HUSP) mining has been considered as an important research topic in data mining. Although some algorithms have been proposed for this topic, they incur the problem of producing a large search space for HUSPs. The tighter utility upper bound of a sequence can prune more unpromising patterns early in the search space. In this paper, we propose a sequence expected utility (SEU) as a new utility upper bound of each sequence, which is the maximum expected utility of a sequence and all its descendant sequences. A sequence utility list for each pattern is used as a new data structure to maintain essential information for mining HUSPs. We devise an algorithm, high sequence utility list-span (HSUL-Span), to identify HUSPs by employing SEU. Experimental results on both synthetic and real datasets from different domains show that HSUL-Span generates considerably less candidate patterns and outperforms other algorithms in terms of execution time.

• KIPS Transactions on Software and Data Engineering
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• 제4권11호
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• pp.499-508
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• 2015

High utility itemset(HUI) mining refers to the discovery of itemsets with high utilities which are not less than a user-specified minimum utility threshold, by considering both the quantities and weight factors of items in a transaction database. Recently the utility-list based HUI mining algorithms have been proposed to avoid numerous candidate itemsets and the algorithms need the costly join operations. In this paper, we propose a new HUI mining algorithm, using the utility-list with additional attributes of transaction utility and common utility of itemsets. The new algorithm decreases the number of join operations and efficiently prunes the search space. Experimental results on both synthetic and real datasets show that the proposed algorithm outperforms other recent algorithms in runtime, especially when datasets are dense or contain many long transactions.

• Proceedings of the Korean Society of Computer Information Conference
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• 한국컴퓨터정보학회 2020년도 제62차 하계학술대회논문집 28권2호
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• pp.81-82
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• 2020

Non-convex 최적화 문제의 복잡도를 완화하도록 해주는 오목함수 결정규칙을 제안한다. 전송용량을 나타내는 유틸리티 함수는 신호와 간섭의 함수이며, non-convex이다. 유틸리티 함수를 간섭관점에서 분석한다. '상대간섭'과 '간섭주요화'를 정의한다. 상대간섭은 D2D 수신단에서의 간섭레벨을 나타낸다. 간섭주요화는 간섭을 주요간섭으로 간략화한다. 간섭주요화를 기반으로 하는 오목함수 결정규칙을 제안한다. 실험결과를 통하여 유틸리티 함수는 상대간섭 0.1 이하에서는 오목함수임을 확인하였다.

• KIPS Transactions on Computer and Communication Systems
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• 제1권3호
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• pp.119-124
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• 2012

As an energy network infrastructure, which is capable of integrating energy related services such as AMR/AMI, Smart Grid, and Smart Water Grid, the Smart Utility Network (SUN) enables a paradigm shift from user-oriented networks to device-oriented networks. The SUN has some similarities to sensor networks in application and network requirements. Therefore it is required to investigate and analyze thoroughly existing related work in advance to design new network protocols for SUN. In this paper we analyze service requirements and design considerations for SUN and then present a design guideline of new network protocols for SUN by investigating existing low power protocols, data aggregation methods, and in-network storages.

• Journal of KIISE:Databases
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• 제36권5호
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• pp.341-351
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• 2009

Recently high utility pattern (HUP) mining is one of the most important research issuer in data mining since it can consider the different weight Haloes of items. However, existing mining algorithms suffer from the performance degradation because it cannot easily apply Apriori-principle for pattern mining. In this paper, we introduce new high utility pattern mining approach by using a prefix-tree as in FP-Growth algorithm. Our approach stores the weight value of each item into a node and utilizes them for pruning unnecessary patterns. We compare the performance characteristics of three different prefix-tree structures. By thorough experimentation, we also prove that our approach can give performance improvement to a degree.

• Korean Chemical Engineering Research
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• 제46권1호
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• pp.147-155
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• 2008

The economics of most chemical plants are heavily dependent upon the management of the utilities used in the plants. The utilities are supplied by the centralized utility system of the plant. Among the various utilities the steam is by far the most important energy source and the management of the electricity and the process water are greatly affected by the steam. Therefore it is necessary to educate students and new employees the basic concepts about the effective distribution of the utilities and the fundamental strategies to apply the concepts in actual plant operations. The OOUS (Optimal Operation of Utility System) is an GUI educational system designed to educate the effective generation of the steam and the optimal steam distribution schemes within short period. The OOUS deals with various utility equipments and processes and shows how to save operation costs by displaying the optimal operation conditions based on the process models and the operational knowledgebase.

• Korean Chemical Engineering Research
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• 제45권3호
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• pp.234-241
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• 2007

To achieve safe operation and to improve economics it is imperative to monitor and analyse demand and supply of utilities and to meet utility needs in time. The main objective of motor/turbine processes is to manipulate steam and electricity balances in utility plants. The optimal operation of motor/turbine processes is by far the most important to improve economics in the utility plant. In order to analyse motor/turbine processes, we need steady state models for steam generation equipments and steam distribution devices as well as turbine generators. In addition heuristics concerning various operational situations are required. The motor/turbine optimal operation system is based on utility models and operational knowledgebase and provides optimal operating conditions when the amount of steam demand from various steam headers is changed frequently. The optimal operation system also produces optimal selection of driving devices for utility pumps to reduce operating cost.

• Journal of KIISE:Information Networking
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• 제33권1호
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• pp.103-112
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• 2006

Priority-based network service has been widely adopted for the Internet traffic management in the context of IETF differentiated services, and computing optimal prices for such priority-based service is the key topic in many pricing literature. While the equilibrium analysis has been commonly used to this end, many have criticized the validity of the underlying assumption of equilibrium analysis that user utility functions are precisely known. In this paper, we propose a solution for bridging the gap between the existing theoretical work on optimal pricing and the unavailability of precise user utility information in real networks. In the proposed method, the service provider obtains more and more accurate estimates of user utility functions from the initial imprecise knowledge by iteratively changing the price of service levels and observing the users' decisions under the changed price. Our contribution is two-fold. First, we have developed a general principle for estimating the user utility functions. Second, we have developed a novel method for setting the prices that can optimize the extraction of the knowledge about user utility functions. The extensive simulation results demonstrate the effectiveness of our method.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• 제8권10호
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• pp.25-32
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• 2018

Recently, the complexity of underground utilities has increased and it has became more difficult to identify and manage information about all underground utilities due to changes such as road extension or building relocation. As a result, number of accidents related to underground utilities caused by excavation works or disasters are in rise, and naturally damages as well are increasing due to the accidents. Therefore, there is a need for a management system capable of easily registering or retrieving information of underground utilities from a remote place. In our previous work, we have developed a utility labelling system based on NFC (Near Field Communication) tag and a utility management system based on IoT (Internet of Things). However, in general, there are diverse communication devices and protocols in IoT environment. Therefore, in this paper, we propose management system and IoT gateway that enables smooth communication even in different types of devices based on the previous our work.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제25권11A호
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• pp.1724-1731
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• 2000

인터넷 서비스 풀질 레벨의 효과적인 관리는 고객과 서비스 제공자 모두에게 점자 중요해지고 있다. 본 논문에서서는 인터넷 서비스를 위한 서비스 레벨 협정 관리의 문제를 수학적으로 제시하고, 제시된 문제의 휴리스틱 해를 도출한다. 문제를 풀기 위해, 서비스 레벨 협정의 관리와 제어적인 측면을 나타내기 위한 유틸리티 모델을 제안한다. 유틸리티 모델을 이용한 SLA 관리의문제 정형화 및 휴리스틱 해는 인터넷 서비스에대한 승인 제어 및 품질 적응에 계산적으로 실현 가능한 해결책을 제공해준다. 마지마긍로 VoIP 서비스 시뮬레이션을 통해 제시된 해의 성능을 평가한다.