• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.517-521
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• 2008

A worm is a malware that propagates quickly from host to host without any human intervention. Need of early worm detection has changed research paradigm from signature based worm detection to the behavioral based detection. To increase effectiveness of proposed solution, in this paper we present mechanism of detection and prevention of worm in distributed fashion. Furthermore, to minimize the worm destruction; upon worm detection we propagate the possible attack aleγt to neighboring nodes in secure and organized manner. Considering worm behavior, our proposed mechanism detects worm cycles and infection chains to detect the sudden change in network performance. And our model neither needs to maintain a huge database of signatures nor needs to have too much computing power, that is why it is very light and simple. So, our proposed scheme is suitable for the ubiquitous environment. Simulation results illustrate better detection and prevention which leads to the reduction of infection rate.

• Proceedings of the Korea Database Society Conference
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• 2010.06a
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• pp.249-264
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• 2010

Mobile banking is a subset of electronic banking which underlies not only the determinants of the banking business but also the special conditions of mobile commerce. Nowadays wireless networks are being evolved and diversified. In this situation The wireless e-commerce is in the limelight on new profits of Carriers. Because of this situation, the importance of mobile billing service is being emphasized. This paper searches the definition and service types of mobile banking, and suggests status and prospects of domestic mobile banking. We suggest the basic direction, the stage of development and functions of services by analyzing the cases of Nonghyup's. Finally we derive the critical factors from those and suggest the effect of introduction and the direction of development. From the customer perspective, mobile banking has many strengths. For example, it allows that all customers access banking service at anytime, anywhere more easily than telephone banking or pc banking. And it reduces the time and the effort for using the service. It enables the company to make a business against global customers. On the other hand, from the company perspective, it has a lot of potential that affect market share and reduce the costs of human and material resources which used to operate and support branches. However, it needs many efforts to reach at the stage of completion. And We will have to solve the problems that develop many contents, expend the range of services and raise the service convenience.

• Proceedings of the Korea Database Society Conference
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• 2002.10a
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• pp.51-59
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• 2002

오늘날 비즈니스의 가장 중요한 요소 중의 하나는 타이밍이며, 이의 예측 정확성이나 대응력에 따라 비즈니스의 성패 정도가 달라질 수 있다. 이러한 의사결정력을 강화하기 위해서 많은 기업에서는 글로벌 선도시장의 흐름이나 선진기업의 성공전략에 대한 벤치마킹을 수행한다. 모바일 산업에 관한 한 한국은 글로벌 선도시장으로, 한국의 휴대폰 시장 변천을 분석하고 구매요인 및 요인간 관계를 규명하여 지표화할 수 있으면 여타 국가에서 시장주도 전략에 중요한 역할을 수행할 수 있을 것으로 예상된다. 따라서 테크놀로지 수용에 대한 기존 문헌연구를 바탕으로 끊임없이 변화하는 정보기술 제품이나 서비스의 수용 여부 및 시장 성장 예측에 대한 프레임워크를 개발 제시하는 것이 본 연구의 기본 목적이다. 개인차원의 기술 수용 모형인 Technology Acceptance Model(TAM) 및 여러 수정모형에서 규명된 다양한 변수들은 실증적인 연구의 결과로서 중요성은 갖으나, 여전히 연구 및 실무 관점에서는 특정 상황에 대한 통계 분석 결과의 제시라는 점에서 한계를 갖는다. 비교 대상국으로 선택한 중국은 그 국토만큼, 인구만큼, 문화만큼 다양하고 복합적인 시장이며, 동시에 누구나 공감하는 거대한 잠재시장이므로, 한국시장의 분석을 바탕으로 중국시장에 대한 향후 성장을 지표로 예측할 수 있다면 국내 기술 및 상품 수출의 기회를 보다 더 수익성있게 포착할 수 있을 것이라고 판단했기 때문이다. 그러나 여기서는 연구의 의의, 대표적인 일부 변수의 평가와 연구방법에 대한 제안에 국한하여 설명한다.

• Journal of KIISE:Databases
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• v.37 no.1
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• pp.22-32
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• 2010

Location-based services have been expanded rapidly in local and overseas markets due to technological advances and increasing applications of wireless internet. Various researches have been made to manage efficiently the location information of moving objects. A basic location-based alert service provides alerting messages automatically when either entering or leaving a specific location and it is expected to become one of the most important location-based services. Location-based alert services require a location polling method to acquire current locations for a large number of moving objects. However, a simple periodical location polling method causes severe system overload because a system should keep updating location information of the moving objects ceaselessly. Most location polling algorithms for location-based alerting services are not suitable for mobile users with dynamic and unsteady moving patterns. In this paper, we propose an improved location polling algorithm for location-based alerting services to reduce the amount of location information acquisition and therefore, to decrease the system load. Various experiments show that the proposed algorithm outperforms other algorithms.

• Journal of Korea Spatial Information System Society
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• v.8 no.2 s.17
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• pp.53-73
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• 2006

Recently, the need for Location-Based Services (LBS) has increased due to the development of mobile devices, such as PDAs, cellular phones and GPS. As a moving object database that stores and manages the positions of moving objects is the core technology of LBS, the scheme for maintaining the main memory DBMS to the server is necessary to store and process frequent reported positions of moving objects efficiently. However, previous works on a moving object database have studied mostly a disk based moving object index that is not guaranteed to work efficiently in the main memory DBMS because these indexes did not consider characteristics of the main memory. It is necessary to study the main memory index scheme for a moving object database. In this paper, we propose the main memory index scheme based on the R-tree for storing and processing positions of moving objects efficiently in the main memory DBMS. The proposed index scheme, which uses a growing node structure, prevents the splitting cost from increasing by delaying the node splitting when a node overflows. The proposed scheme also improves the search performance by using a MergeAndSplit policy for reducing overlaps between nodes and a LargeDomainNodeSplit policy for reducing a ratio of a domain size occupied by node's MBRs. Our experiments show that the proposed index scheme outperforms the existing index scheme on the maximum 30% for range queries.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.631-643
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• 2006

Moving objects in a mobile environment to change their position based on the change of time require a query with their position as a basis. Efficient Regional Decision for Continuous Skyline Queries requires objectively pre-calculating the OSR(Optimal Skyline Region) regardless of the speed and direction of the moving objects. It proposes techniques to reduce the frequency of continuous queries by choosing a VCircle(Validity Circle) as safe location which has radius of the distance to the closest region with position on the moving object at center. But, a VCircle's area varies based on the Moving object's position from first marked time of continuous query. Therefore, the frequency of its continuous query is variable and also when the object moves inside of OSR, query can re-occur frequently In this paper, we suggest a technique of selecting an IVCircle(Interior Validity Circle) in a Skyline Region as the static Safe Region using the characteristics of the OSR. An Interior IVCircle can be calculated in advance when the OSR is decided. Our experiment shows that the frequency of using IVcircle as safe region reduced than that of using VCircle as safe region by 52.55%.

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.600-619
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• 2006

According to recent technical advances on sensors and mobile devices, processing of data streams generated by the devices is becoming an important research issue. The data stream of real values obtained at continuous time points is called streaming time-series. Due to the unique features of streaming time-series that are different from those of traditional time-series, similarity matching problem on the streaming time-series should be solved in a new way. In this paper, we propose an efficient algorithm for streaming time- series matching problem that supports normalization transform. While the existing algorithms compare streaming time-series without any transform, the algorithm proposed in the paper compares them after they are normalization-transformed. The normalization transform is useful for finding time-series that have similar fluctuation trends even though they consist of distant element values. The major contributions of this paper are as follows. (1) By using a theorem presented in the context of subsequence matching that supports normalization transform[4], we propose a simple algorithm for solving the problem. (2) For improving search performance, we extend the simple algorithm to use $k\;({\geq}\;1)$ indexes. (3) For a given k, for achieving optimal search performance of the extended algorithm, we present an approximation method for choosing k window sizes to construct k indexes. (4) Based on the notion of continuity[8] on streaming time-series, we further extend our algorithm so that it can simultaneously obtain the search results for $m\;({\geq}\;1)$ time points from present $t_0$ to a time point $(t_0+m-1)$ in the near future by retrieving the index only once. (5) Through a series of experiments, we compare search performances of the algorithms proposed in this paper, and show their performance trends according to k and m values. To the best of our knowledge, since there has been no algorithm that solves the same problem presented in this paper, we compare search performances of our algorithms with the sequential scan algorithm. The experiment result showed that our algorithms outperformed the sequential scan algorithm by up to 13.2 times. The performances of our algorithms should be more improved, as k is increased.