• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.73-77
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• 1996

정보는 의사결정자들의 수주에 있을 때 기업에 있어 강력한 경쟁무기가 된다. 의사결정자들의 정보에 대한 이러한 필요성을 충족시키기 위해서 데이타는 운영시스템(Operational System)에서 추출되어 데이타웨어하우스에 저장된다. 데이타웨어하우스는 핵심 비지니스영역(key business dimension)에 의해 정리된 historical data를 저장한다. 이러한 의사결정자들을 위한 데이타웨어하우스 정보의 전달은 기존의 클라이언트/서버 시스템 하에서는 많은 지원을 요구한다. 즉 기존 클라이언트/서버 시스템 하에서는 사용자들의 접근을 위해 데이타가 추출되고 조직화되어지고 나면, 반드시 분석 소프트웨어가 각 사용자의 컴퓨터에 설치되어야 하고 외부의 사용자를 위한 새로운 운영자가 고용되어야 한다. 사용자의 다양한 요구 그리고 계속적 사용자의 교체는 사용자 지원에 있어 심각한 기업부담으로 작용한다. 또한 클라이언트/서버 시스템에서는 기업외부의 정보 이용자들에게 정보를 제공하는데 있어 장소적 한계점을 가지고 잇다. 인트라넷과 인터넷은 이러한 클라이언트/서버 시스템 환경의 문제에 대해 해답을 제시한다. 인트라넷은 데이타웨어하우스로의 접근을 간단히 할뿐만 아니라 의사결정자들의 정보의 공유와 상호분석의 새로운 단계를 제공한다. 그리고 인터넷은 기업 외부 어디에서나 기업이 제공하는 정보를 이용하고자 하는 사람들에게 접근의 편의성을 제공한다. 즉 데이타웨어하우스의 목표와 인트라넷, 인터넷의 목표는 데이타로의 손쉬운 접근이라는 점에서 동일하다. 이러한 점에 착안하여 인트라넷과 인터넷하에서 운용되는 데이타웨어하우스 시스템 구축을 위한 방안을 제시하고자 한다.다(학생군:8.16kg 작업자군:12.9kg). 심박수를 이용한 생리학적 연구에서는 평균 심박수가 거의 100 이하를 유지하므로써 피실험자들이 8시간 작업기준으로 보아 무리가 없는 최대허용 하중을 결정하였음을 보였다. 또한 각 운반작업에 대한 최대허용 하중을 예측하는 회귀모형을 제시하였다.아직 정립되어 있지 않은 분산 환경하에서의 관계형 데이타베이스의 데이타관리의 분류체계를 나름대로 정립하였다는데 그 의의가 있다. 또한 이것의 응용은 현재 분산데이타베이스 구축에 있어 나타나는 기술적인 문제점들을 어느정도 보완할 수 있다는 점에서 그 중요성이 있다.ence of a small(IxEpc),hot(Tex> SOK) core which contains two tempegatlue peaks at -15" east and north of MDS. The column density of HCaN is (1-3):n1014cm-2. Column density at distant position from MD5 is larger than that in the (:entral region. We have deduced that this hot-core has a mass of 10sR1 which i:s about an order of magnitude larger those obtained by previous studies.previous studies.업순서들의 상관관계를 고려하여 보다 개선된 해를 구하기 위한 연구가 요구된다. 또한, 준비작업비용을 발생시키는 작업장의 작업순서결정에 대해서도 연구를 행하여, 보완작업비용과 준비비용을 고려한 GMMAL 작업순서문제를 해

• Journal of Internet Computing and Services
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• v.18 no.5
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• pp.31-38
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• 2017

Recently with the rapid development of LBS (Location-based Services) technology, approaches of protecting user's location have gained tremendous attentions. For using LBS, users need to forward their real locations to LBS server. However, if the user sends his/her real location to LBS server, the server will have the all the information about user in LBS. Moreover, if the user opens it to LBS server for a long time, the trajectory of user may be released. In this paper, we propose GTC (Grid-based Trajectory Cloaking) method to address the privacy issue. Different from existing approaches, firstly the GTC method sets the predicting trajectory and divides the map into $2^n*2^n$ grid. After that we will generate cloaking regions according to user's desired privacy level. Finally the user sends them to LBS server randomly. The GTC method can make the cost of process less than sequential trajectory k-anonymity. Because of confusing the departure and destination, LBS server could not know the user's trajectory any more. Thus, we significantly improve the privacy level. evaluation results further verify the effectiveness and efficiency of our GTC method.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.8
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• pp.195-202
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• 2018

With the development of location-based applications such as smart phones and GPS navigation, active research is being conducted to protect location and trajectory privacy. To receive location-related services, users must disclose their exact location to the server. However, disclosure of users' location exposes not only their locations but also their trajectory to the server, which can lead to concerns of privacy violation. Furthermore, users request from the server not only location information but also multimedia information (photographs, reviews, etc. of the location), and this increases the processing cost of the server and the information to be received by the user. To solve these problems, this study proposes the EGTC (Enhanced Grid-based Trajectory Cloaking) technique. As with the existing GTC (Grid-based Trajectory Cloaking) technique, EGTC method divides the user trajectory into grids at the user privacy level (UPL) and creates a cloaking region in which a random query sequence is determined. In the next step, the necessary information is received as index by considering the sub-grid cell corresponding to the path through which the user wishes to move as c(x,y). The proposed method ensures the trajectory privacy as with the existing GTC method while reducing the amount of information the user must listen to. The excellence of the proposed method has been proven through experimental results.

• Spatial Information Research
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• v.18 no.3
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• pp.53-62
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• 2010

Recent development in wireless communication technology, like GPS, and mobile equipments, like PDA and cellular phone, make location-based services (LBSs) popular. However, because, users continuously request a query to a server in the LBSs by using their exact locations, privacy information could be in danger. Therefore, a mechanism for users' privacy protection is required for the safe and comfortable use of LBSs by mobile users. For this, we, in this paper, propose a grid-based cloaking area creation scheme supporting continuous LBSs in peer-to-peer environment. The proposed scheme creates a cloaking area by using Chord protocol, so as to support the continuous LBSs in peer-to-peer environment. Finally, we show from a performance analysis that our cloaking scheme outperforms the existing cloaking schemes, in terms of service time.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.155-166
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• 2005

Currently, almost of all the Internet users have as many IDs as the number of sites they have subscribed for, The users should memorize and input every independent ID and password whenever they want to login to the system. Although ID management system is used to solve this problem, 10 and password management will become more complicated in the forthcoming ubiquitous computing environments because so many computers will be interconnected on various kinds of wired and wireless networks, Furthermore, it is not enough to use the existing single Circle of Trust (COT) ID management system for the forthcoming computing environments. To solve this problem, the paper proposes ID federation models in multiple COT domain and implements an ID federation system that can be scaled to mobile computing environment as well as wired computing environment. The proposed ID federation models has been verified to operate with no problem between the systems in different trust domains by doing the ID scaability test.

• Journal of Internet Computing and Services
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• v.14 no.4
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• pp.85-90
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• 2013

Currently, the electric fire prediction system uses PIC(Peripheral Interface Controller) for controller microprocessor. PIC has a slower computing speed than DSP does, so its real-time computing ability is inadequate. So with the basic characteristics waveform during arc generation as the standard reference, the comparison to this reference is used to predict and alarm electric fire from arc. While such alarm can be detected and taken care of from a remote central server, that prediction error rate is high and remote control in mobile environment is not available. In this article, the arc detection of time domain and frequency domain and wavelet-based adaptation algorithm executing the adaptation algorithm in conversion domain were applied to develop an electric fire prediction system loaded with new real-time arc detection algorithm using DSP. Also, remote control was made available through iPhone environment-based app development which enabled remote monitoring for arc's electric signal and power quality, and its utility was verified.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.157-163
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• 2021

A single write operation in a file system can modify multiple data, but these changes in the file system are not atomically written to disk. Thus, for the consistency of the file system, conventional journaling guarantees crash consistency instead of sacrificing the system performance. It is known that using non-volatile memory as a journal space can alleviate performance degradation due to low latency and byte-level accessibility of non-volatile memory. However, none of the journaling techniques considering non-volatile memory provide scalability. In this paper, journal space on non-volatile memory is divided into multiple regions for scalable journaling, thus dispersing concentrated operations in one region. Second, the journal area-specific operator structure is used to accelerate data write operations to storage devices. We apply the proposed technique to JFS to evaluate it on multi-core servers equipped with high-performance storage devices. The evaluation results show that the proposed technique performs better than the existing technique of the NVM-based journaling file system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.473-483
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• 2012

To achieve an entire end-to-end security, the classical authentication setting such that all participants have a same password is not practical since a password is not a common secret but a personal secret depending on an individual. Thus, an efficient client to client different password-based authenticated key agreement protocol (for short, EC2C-PAKA) has been suggested in the cross-realm setting. Very recently, however, a security weakness of the EC2C-PAKA protocol has been analyzed by Feng and Xu. They have claimed that the EC2C-PAKA protocol is insecure against a password impersonation attack. They also have presented an improved version of the EC2C-PAKA protocol. In this paper, we demonstrate that their claim on the insecurity of EC2C-PAKA protocol against a password impersonation attack is not valid. We show that the EC2C-PAKA protocol is still secure against the password impersonation attack. In addition, ironically, we show that the improved protocol by Feng and Xu is insecure against an impersonation attack such that a server holding password of Alice in realm A can impersonate Bob in realm B. We also discuss a countermeasure to prevent the attack.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.733-735
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• 2005

모델링$\cdot$시뮬레이션 또는 첨단 센서 장비 기술의 발전으로 최근에 매우 높은 해상도를 갖는 방대한 크기의 볼륨 데이터들이 생성되고 있으며, 이러한 데이터를 효과적으로 가시화하기 위한 다양한 연구 결과들이 과학적 가시화 분야에서 발표되고 있다. 지금까지 연구된 대부분의 가시화 소프트웨어들은 워크스테이션과 PC를 기반으로 개발되었으며, 모바일 환경에서 가시화를 수행하는 소프트웨어는 아직까지 발표된 바가 없다. 본 논문에서는 PDA상에서 구현된 클라이언트와 대용량$\cdot$고성능 서버를 이용한 모바일 볼륨 가시화 시스템의 설계에 관해 설명한다. 이 시스템은 자세한 관찰이 필요한 특정 영역을 점진적으로 높은 해상도로 관찰할 수 있는 기능을 지원하여, 설정한 파라미터를 이용한 고화질 볼륨 가시화 영상의 렌더링을 요청하는 기능을 제공한다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.679-681
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• 1999

최근 웹의 폭발적인 성장으로 인하여 웹을 교육의 매개체로 활용하려는 노력이 활성화되고 있다. 그러나 현재 대부분의 웹 기반 교육 시스템들은 대체로 수동적이며, 정적인 하이퍼텍스트 위주이기 때문에, 학습상황을 수시로 점검할 수 있는 상호작용기능이 부족하고, 특정 학습자의 학습결과에 따른 동적인 학습환경의 제시가 어렵다. 일반적으로 웹기반 교육시스템은 다양한 지식계층의 사람들에게 노출되어 있기 때문에 보다 상세한 학습전략이 요구되며, 따라서 최근에는 기존의 지능형 교수시스템(Intelligent Tutoring System: ITS)에서 연구된 풍부한 기술들을 웹 환경에 도입함으로서 보다 지능적이며 적응력 있는 시스템개발에 관한 연구가 활성화되고 있다. 본 연구에서는 이러한 웹 기반 교육시스템에서의 문제점들을 해소하기 위한 한가지 방안으로 ITS의 동적 교수계획기법을 웹 기반 시스템에 도입한다. 문제영역으로 C 프로그래밍 언어 학습을 선정하여 이를 웹 기반 교수시스템으로 설계하고 구현하였다. 또한 기존 시스템들의 서버 집중형 구조에서 탈피하여 CORBA를 이용한 분산기반구조로 시스템 개발에 접근하였다.