• KIPS Transactions on Computer and Communication Systems
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• v.11 no.12
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• pp.429-436
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• 2022

Temporary files are generated when the Hash Join is performed on tables larger than the memory. During the join process, each temporary file is deleted sequentially after it completes the I/O operations. This paper reveals for that the fallocate system call and file deletion-related trim options significantly impact the hash join performance when temporary files are managed on SSDs rather than hard disks. The experiment was conducted on various commercial and research SSDs using PostgreSQL, a representative open-source database. We find that it is possible to improve the join performance up to 3 to 5 times compared to the default combination depending on whether fallocate and trim options are used for temporary files. In addition, we investigate the write amplification and trim command overhead in the SSD according to the combination of the two options for temporary files.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.250-251
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• 2016

사물인터넷은 기존의 여러 ICT기술과 유,무선 장비의 네트워크 및 다양한 통신 기술들이 적용된 것을 의미한다. 최근 다양한 사물 인터넷에 대한 발전은 경량화, 소형화 되어가며 OSHW(Open Source HardWare)을 기반으로 점차 다양화 되었다. 이에 따라 사물인터넷 다양한 디바이스와 펌웨어, 암호학에 대한 연구는 활발하게 진행되고 있다. 하지만 특정 하드웨어의 센서 디바이스에 대한 연구는 부족하다. 본 논문에서는 OSHW 중 하나인 AVR기반의 아두이노 개발도구에 대한 임시 파일에 대해 분석하고 메모리 초기화 방법에 대해 제안한다. 또한 임시파일을 이용한 메모리 초기화 방법을 이용하여 사용자정보와 메모리 공격에 대한 데이터 유출을 방지할 수 있다.

• Review of KIISC
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• v.22 no.8
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• pp.21-25
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• 2012

최근 해킹 및 개인정보 유출로 인한 관공서 개인정보 취급에 대한 사회적 불신감 팽배, 신뢰도 저하 문제가 발생하고 있다. 개인정보보호법, 정보통신망법의 강화에도 불구하고, 업무에 활용된 명부 등이 저장된 위치를 기억하지 못하여 그대로 방치되고 있으며, 자료공유시스템 등 웹사이트를 통해 열람(접근)된 개인정보파일이 개인 PC내 임시파일로 PC의 하드디스크에 저장되어 있다. 개인정보보호법은 2011년 3월 29일 공포되었고, 9월 30일부터 전면 실시되었다. 본 논문에서는 PC의 개인정보를 검색하고 검색된 파일을 암호화, 파일숨김을 하여 파일을 안전하게 보관하게 하며, 사용기간이 지난 파일의 경우 완전삭제를 하여 PC에서 개인정보보호법에 대응 방안을 제시한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1059-1064
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• 2018

Many users feel a great pain owing to losing edited files. It is very serious loss in time and money. This problem occurs because email attachments are edited in 'Inbox' and the compute immediately shuts down with 'Save'. This is caused by the illusion that the 'save' in a temporary folder is saved to a secure hard disk. Our thesis proposes a loss-prevention system WatchDog for safe storage and folder management of the e-mail attachments. The proposed system operates a warning window pop-up when we 'Open(O)' and 'Save' the attachment. In addition, convenient folder management plans for safe copying and movement are shown through example programs.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.63-74
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• 2004

Temporal locality of Web server references is one of the important characteristics to be considered in the design of a Web caching strategy, and it is important to measure the temporal locality exactly. Various methods to estimate the temporal locality have been proposed, however, Web server designers have still troubles in its measurement by using the tools that don't reflect the interarrival time of document requests. In this paper, we propose a measurement tool for short-term temporal locality based on request interarrival time, and discuss the simulation results based on the flares from NLANR and NASA Web sites. The results show that the proposed tool estimates the short-term temporal locality more exactly than that based on a stack.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.11a
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• pp.621-624
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• 2006

한국과학기술정보연구원에서는 대규모 파일시스템을 IBM p690시스템에서 운영 중에 있다. 이 파일 시스템은 정해진 쿼터 정책에 따라서 운영되는 홈 파일시스템과 사용자의 작업 수행시에 필요로 하는 입력, 출력파일 및 임시 파일을 저장하는 스크래치 파일시스템으로 사용되고 있다. 공용으로 사용되어지는 스크래치 파일시스템에 일정 기간이 경과한 파일들이 무분별하게 남아있게 되면 디스크의 가용 공간을 차지하게 되어 정상적인 작업수행에 방해를 받게 된다. 본 고에서는 스크래치 파일시스템에 존재하는 파일들을 검사하여 일정 기간이 지나서도 남아 있는 사용자 파일을 삭제함으로써 스크래치 파일시스템의 가용 공간을 확보하는 프로그램을 개발하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.208-210
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• 2003

기존의 바다-II는 늦은 프로젝션(late projection) 기법을 사용하기 때문에 중간 임시 결과 파일의 디스크 쓰기와 디스크 읽기에 많은 디스크 자원, 메모리 자원, 그리고 CPU 시간이 소모되었다. 본 논문은 바다-II에 조기 프로젝션(early projection) 기법의 설계와 구현 그리고 그에 따른 성능 향상을 보인다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6274-6281
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• 2015

Radio-based train control system has driving headway shortening effect by real-time train interval control using two-way radio communication between onboard and wayside systems, and reduces facility investment because it does not require any track-circuit. Automatic train protection(ATP), the most significant part of the radio-based train control system, makes sure a safe distance between preceding and following trains, based on real-time train location tracing. In this paper, we propose the overall ATP train interval control algorithm to control the safe interval between trains, and preprocessing-based speed profile calculation algorithm to improve the processing speed of the ATP. The proposed speed profile calculation algorithm calculates the permanent speed limit for track and train in advance and uses as the most restrictive speed profile. If the temporary speed limit is generated for a particular track section, it reflects the temporary speed limit to pre-calculated speed profile and improves calculation performance by updating the speed profile for the corresponding track section. To evaluate the performance of the proposed speed profile calculation algorithm, we analyze the proposed algorithm with O-notation and we can find that it is possible to improve the time complexity than the existing one. To verify the proposed ATP train interval control algorithm, we build the train interval control simulator. The experimental results show the safe train interval control is carried out in a variety of operating conditions.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.245-256
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• 2023

When restoring with a dental digital system for implant-supported prosthesis, a double digital scanning technique is required: an intraoral scan of the three-dimensional implant location and intraoral scan after placement of temporary denture or provisional prosthesis. During the intraoral scan, the use of scan body as a stable landmark can improve the accuracy of digital impression and simplify laboratory process. In this case, a full-digital system was used to plan and fabricate a custom abutment, provisional prosthesis, and definitive prosthesis. After implant placement, the scan area of the intraoral scan body connected with implant and the intraoral scan body marked on the inside of temporary denture were superimposed. Out of the superimposed files, a custom abutment and provisional prosthesis were fabricated which match the vertical dimension of temporary denture, and definitive prosthesis was fabricated based on provisional prosthesis. We report this case because result has been functionally and esthetically satisfactory by using vertical dimension and central relation set during the fabrication of temporary denture to the definitive prosthesis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.316-321
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• 2017

With the recent wide adoption of Linux in the fields of IoT, embedded, mobile, desktop and server industries, the importances of understanding the Linux system architecture as well as customizing the Linux system are increasing very steeply. Accordingly, the capabilities of building every component of Linux system from source code files have been important. The LFS (Linux From Scratch) site[1] guides the steps of building the basic Linux system from source files. The steps consist of build host preparation step, temporary system building step, final system building step, and system configuration and boot preparation step. However, the underlying concepts behind the steps used in building LFS are difficult to understand, particularly to the beginner. This paper analyzes the LFS build steps and reveal the core build concepts and principles used in each step. Additionally, this paper shows the measured package build times obtained from our build experience.