• Journal of KIISE:Databases
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• v.31 no.3
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• pp.243-251
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• 2004

Most programs of bioinformatics provide biochemists and biologists retrieve and analysis services of gene and protein database. As these services retrieve database for each arrival of user's request, it takes a long time and increases server's load and response time. In this paper. by utilizing database retrieval patterns of sequence alignment programs in bioinformatics, grouping method is proposed to share database retrieval between many requests. Carpool method is also proposed to reduce response time as well as to increase system expandability by combining new arriving requests with the previous on going requests. The performance of our two proposed schemes is verified by mathematic analysis and simulation.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.365-371
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• 2021

With the rapid growth in Internet users, web applications are becoming the main target of hackers. Most previous WAFs (Web Application Firewalls) target every single HTTP request packet rather than the overall behavior of the attacker, and are known to be difficult to detect new types of attacks. In this paper, we propose a web attack detection system based on user behavior using machine learning to detect attacks of unknown patterns. In order to define user behavior, we focus on features excluding areas where an attacker can camouflage as a normal user. The experimental results shows that by using the path and query information to define users' behaviors, best results for an accuracy of 99% with Decision forest.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.286-288
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• 2001

미래에는 Mobile IP의 이동 노드 사용자가 증가할 것이기 때문에 보다 효율적인 이동성 관리 기법이 필요할 것이다. 특히 이동 노드의 수가 증가함에 따라 이동성을 지원하기 위한 바인딩 갱신 메시지 수는 증가한다. 따라서 , 본 논문에서는 이동 노드의 이동성 패턴의 지역적 특성이 반영된 프로파일 정보를 이용하여 네트워크 상에서 바인딩 갱신 메시지의 라이프타임 값을 조정함으로써 바인딩 갱신 메시지의 수를 감소시킬 수 있는 프로과일 기반의 전략을 제안한다. 본 논문에서는 이동 노드의 과거 이동성 패턴 정보를 이용하여 이동 노드가 가지고 있는 프로파일의 평균 상주시간 정보를 라이프타임 값으로 설정하는 적응적 라이프타임과 이동성 정보가 없는 경우에 기존 Mobile IPv6에서 사용하는 라이프타임 값을 그대로 사용하는 디폴트 라이프타임이 존재한다. 그리고, Mobile IPv6에서의 효율적인 라우팅을 위해 프로파일 정보에 기반한 두개의 라이프타임을 효율적으로 관리함으로써 바인딩 갱신 메시지와 바인딩 요청 메시지의 수를 감소시킬 수 있으며, 상당한 통신비용 절감효과를 기대할 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.613-615
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• 2004

유무선 통신 기술의 발전으로 언제 어디서나 컴퓨터를 이용하는 유비쿼터스 컴퓨팅에 관심이 집중되고 있다. 하지만 기존의 데이터 관리 방법은 유비쿼터스 컴퓨팅 환경에서 파일 서비스를 제공하는 데 어려움이 있다. 유비쿼터스 컴퓨팅 환경의 파일 시스템은 데이터의 유용성, 응용 프로그램에 대한 투명성, 자동데이터 선택 및 저장, 이질적인 장지의 상호 운용을 지원할 수 있어야 한다. 본 논문에서는 이러한 요구사항을 충족시킬 수 있는 유비쿼터스 파일 시스템(UbiFS)를 제안한다. UbiFS는 클라이언트의 현재 상태를 XML을 이용하여 상황 정보(Situation Information)로 구조화하고 SI 메시지를 통해서 서버에게 서비스를 요청하게 된다. 서비스는 클라이언트의 SI 메시지를 관리하는 매니저를 통해서 데이터 동기화와 같은 문제를 해결한다. 그리고 사용자가 직접 데이터를 선택하는 번거로움을 줄이기 위해서 UbiFS는 사용자의 데이터 접근 패턴을 분석하여 시스템 수준에서 데이터를 자동적으로 선택하고 저장할 수 있다.

• Annual Conference of KIPS
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• 2009.04a
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• pp.1155-1158
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• 2009

모바일 서비스는 사용자보호를 위해 인증 및 암호화 기능이 필수적으로 제공되어야만 한다. 3GPP는 3 세대 이동통신 (UMTS)를 위한 인증보안구조인 AKA를 정의하였다. AKA에서는 인증벡터를 다수 개 생성하여 처리하는 기법을 채택하고 있으나 이러한 기법이 인증서버의 load 증가 및 방문서버의 저장공간 소모라는 문제점을 야기한다. 하지만 인증벡터를 다수 개 생성하는 기법은 단말의 핸드오버를 위한 필수불가결한 기법이다. 따라서 본 논문에서는 사용자의 이동패턴 및 인증요청 처리 속도에 따른 인증벡터의 동적 선택 알고리즘을 제안하여 이동통신 네트워크의 signaling load를 최소화하고자 한다. 이를 위해 확률 및 큐잉 이론이 도입되었으며, 시뮬레이션을 통해 수학적 분석을 검증한다. 또한 기존 관련연구에서 제안 하는 알고리즘과 비교 평가하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.11
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• pp.369-382
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• 2015

Energy aware server clusters aim to reduce power consumption at maximum while keeping QoS(quality of service) compared to energy non-aware server clusters. They adjust the power mode of each server in a fixed or variable time interval to activate only the minimum number of servers needed to handle current user requests. Previous studies on energy aware server cluster put efforts to reduce power consumption or heat dissipation, but they do not consider energy efficiency well. In this paper, we propose an energy efficient cluster management method to improve not only performance per watt but also QoS of the existing server power mode control method based on autonomous learning. Our proposed method is to adjust server power mode based on a hybrid approach of autonomous learning method with multi level thresholds and power consumption prediction method. Autonomous learning method with multi level thresholds is applied under normal load situation whereas power consumption prediction method is applied under abnormal load situation. The decision on whether current load is normal or abnormal depends on the ratio of the number of current user requests over the average number of user requests during recent past few minutes. Also, a dynamic shutdown method is additionally applied to shorten the time delay to make servers off. We performed experiments with a cluster of 16 servers using three different kinds of load patterns. The multi-threshold based learning method with prediction and dynamic shutdown shows the best result in terms of normalized QoS and performance per watt (valid responses). For banking load pattern, real load pattern, and virtual load pattern, the numbers of good response per watt in the proposed method increase by 1.66%, 2.9% and 3.84%, respectively, whereas QoS in the proposed method increase by 0.45%, 1.33% and 8.82%, respectively, compared to those in the existing autonomous learning method with single level threshold.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.2
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• pp.44-53
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• 2000

The waiting delays of users are inevitable in this policy since the services are not taken immediately upon requests but upon every scheduling points. An inefficient management of such delays makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an adaptive batch scheduling scheme which improves the average waiting time of users requests and reduces the starvation problem of users requesting less popular movies. The proposed scheme selects dynamically multiple videos in given intervals based on the service patterns which reflect the popularity distribution(Zipf-distribution) and resource utilizations. Experimental results of simulations show that the proposed scheme improves about 20-30 percentage of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• Journal of KIISE
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• v.44 no.11
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• pp.1165-1177
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• 2017

Many developers utilize specific APIs to develop software, and to identify the use of a particular API, a developer can refer to a website that provides the API or can retrieve the API from the web. However, the site that provides the API does not necessarily provide guidance on how to use it while it can be partially provided in many other cases. In this paper, we propose a novel system JACE (Java AST collocation-pattern extractor) as a method to reuse commonly-used code as a supplement. The JACE extracts the API call nodes, collocation patterns and analyzes the relations between the collocations to extract significant API patterns from the source code. The following experiment was performed to verify the accuracy of a defined pattern: 794 open source projects were analyzed to extract about 15M API call nodes. Then, the Eclipse plug-in test program was utilized to retrieve the pattern using the top 10 classes of API call nodes. Finally, the code search results from reference pages of the API classes and the Searchcode [1] were compared with the test program results.

• Journal of Internet Computing and Services
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• v.21 no.5
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• pp.109-118
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• 2020

Recently, people are spending a lot of time inside their homes because of various diseases. It is difficult to ask others for help in the case of a single-person household that is injured in the house or infected with a disease and needs help from others. In this study, an algorithm is proposed to detect emergency event, which are situations in which single-person households need help from others, such as injuries or disease infections, in their homes. It proposes vision pattern detection algorithms using home CCTVs, audio pattern detection algorithms using artificial intelligence speakers, activity pattern detection algorithms using acceleration sensors in smartphones, and dust pattern detection algorithms using air purifiers. However, if it is difficult to use due to security issues of home CCTVs, it proposes a fusion method combining audio, activity and dust pattern sensors. Each algorithm collected data through YouTube and experiments to measure accuracy.

• Journal of Korea Multimedia Society
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• v.16 no.9
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• pp.1089-1097
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• 2013

The applications for considering their position and daily patterns of dementia patients have been developed in an early stage even if the older patients who have weaker or serious symptoms has increased in various forms. In this paper, we develop an android-based application which displays positions and pathways of patients on maps and provide messages in the cases of dangerous situations. Guardians need to register schedules including safe areas and personal information of their patients. This system registers behavior status categorized as normal or abnormal each position which is sent to a database. In particular, the deviation status is assigned in case the patients are not within the safe areas that their guardians registered on their schedule. The wandering status is assigned in case the patients are repeatedly passed by their pathways. This smart application contains the modules such as patient position sending, guardian and patient information, patient schedule and safe zone registration, position and behavior status registration, pathway display and message sending, and rescue request. This system sends the notification and alarm service providing normal and abnormal behavior with deviation and wandering status of patients respectively.