• Journal of KIISE:Databases
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• v.27 no.4
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• pp.549-561
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• 2000

In database management systems(DBMSs), partial rollback is a useful facility that cancels part of the executed operations upon user's requests without a total rollback. Many relational DBMSs(RDBMSs) provide this facility, However, object-orientccd DBMSs (OODBMSs) cannot utilize the previous recovery scl18lne of partial rollback usccd in (RDBMSs) since, unlike RDBMSs, they use a dual buffer consisting of an object buffer and a page buffer. Therefore, a new recovery scheme is required that rolls back the data efficiently in the dual buffer. We propose four partial rollback schemes in OODBMSs that use a dual buffer. We classify the proposed schemes into the single buffer based partial rollback scheme and the dual buffer based partial rollback scheme according to the number of buffers used for partial rollback processing. We further classify them into Uthe page buffer based partial rollback scheme, 2)the object buffccr based partial rollback scheme, 3)the dual buffer based partial rollback scheme using soft log, and 4)the dual buffer based partial rollback scheme using shadows. We evaluate the performance by mathematical analysis and experiments. The results show that the dual buffer based partial rollback scheme using shadows provides the best performance.

• Convergence Security Journal
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• v.8 no.1
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• pp.57-65
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• 2008

The implement of JAVA API for supporting the embedded system is capable of developing the object oriented system with code reuse because the developer is able to use JAVA in the embedded system. The system dependant parts for implementing JAVA API are realized from a native function. In this paper, we devide JAVA API into the platform-independent JAVA part and platform-dependent native part for the implementation of JAVA API to manage the linux based embedded system devices, and focus on the control of the embedded system devices using JAVA API.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.334-337
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• 2010

디지털 선박 운행시 예기치 못한 상황에 의한 선박 내 화재나 충돌 등 긴급 상황 발생 시에 대형의 해난 사고가 발생할 수 있다. 이에 본 논문에서는 선박 상태를 자체 진단하여 모니터링하고 위험 분석을 통해 관리할 수 있는 시스템을 구현하고자 한다. 해양 디지털선박의 환경, 상황을 수집할 수 있는 무선 센서를 이용하여 수집된 환경 정보를 분석하는 시스템을 제안하였으며, 센싱된 데이터를 분석하기 위하여 역전파 신경망을 설계하였다. 300개의 데이터 집합을 사용하여 역전파 신경망을 실험한 결과 약 96%의 정확도를 가졌다. 제안된 시스템은 하드웨어 (UStar-2400 ISP, UStar-2400, Wireless sensors) 부분과 소프트웨어 부분(User Interface module)으로 구성되며 소프트웨어 부분은 HOST PC에 삽입된다. 그리고 시스템의 정확도를 개선하기 위하여 전방향 에러 정정 시스템(LDPC)을 구현하였고 진단된 결과는 CDMA 방식으로 전송하여 해양디지털선박 감지 모니터링 시스템을 구현했다.

• The KIPS Transactions:PartC
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• v.10C no.6
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• pp.695-704
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• 2003

As wireless Internet speads widely, circulation of various types of digital contents become active. Therefore, it is necesary to make a mobile-based DRM (Digatal Rights Management) system to protect digital contents from illegal reproduction and to give proper rights to contents users, In this paper, we present a mibile security system, which protects the copyright for digital contents offered throughout the mobile environment. Our security system is focused on presenting mobile-based DRM architecture. Especially, considering mobile device's decrying power, we adopted partial encryption scheme. For this, wecompared and evaluated the performant of each contents encryption scheme (the entire encryption scheme and the partial encription scheme) and proved that a proper DRM system for current wireless devices is the partial encryption system. Our mobile DRM system can be very efficient to protect contents on the wireless Internet environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.557-567
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• 2018

There are currently various file encryption solutions for encrypting and storing files on disk. However, the existing file encryption solutions handle encryption and decryption all at once by file or directory. In this paper, we propose a system call supporting partial encryption function of the file. The user sets the encryption information with the system call interface at a portion where encryption of the file data is desired. And then the user writes file data, the data is encrypted and stored. Also if the user sets decryption information and reads the file data, the necessary part is decrypted by applying the set information. For the proposed system call, It consists of inspection module, management module, encryption module, decryption module, and HMAC module as per required system call. And it was implemented on the Linux environment. Also the operation of implemented system call was verified on the development board, and the performance was analyzed by measuring performance speed.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1347-1350
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• 2006

최근 인터넷과 같은 개방된 네트워크의 발달로 데이터의 양이 기하급수적으로 증가하고 있으며 데이터의 단위 크기도 커지고 있다. NEC 시스템에서 이러한 크고 많은 데이터들을 효율적으로 관리하고 컴퓨터의 성능을 최대로 활용하기 위하여 파일 시스템을 설계하고 구현하여 그 성능을 시험하고 분석하였다. 전체 컴퓨터의 성능을 결정하는 요소는 CPU와 메모리, 디스크, 그리고 이들을 연결하는 네트워크 등 여러 가지가 있지만 이러한 각각의 부분적인 시스템 중에서 사용자가 수행할 프로그램 특성에 맞게 설계하여 사용할 수 있는 부분은 파일 시스템이다. 파일 시스템은 전체 시스템의 특성과 사용자의 프로그램 용도를 고려하여 알맞게 설계되면 시스템의 성능을 더 향상시킬 수 있다. 본 논문은 NEC 시스템에서의 파일 시스템을 시스템의 특성과 용도에 맞게 설계하고 테스트하여 그 성능 결과를 분석하였다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.1-10
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• 2007

This paper presents a direct nonlinear multivariable self-tuning PID controller using neural network which adapts to the changing parameters of the nonlinear multivariable system with noises and time delays. The nonlinear multivariable system is divided linear part and nonlinear part. The linear controller are used the self-tuning PID controller that can combine the simple structure of a PID controllers with the characteristics of a self-tuning controller, which can adapt to changes in the environment. The linear controller parameters are obtained by the recursive least square. And the nonlinear controller parameters are achieved the through the Back-propagation neural network. In order to demonstrate the effectiveness of the proposed algorithm, the computer simulation results are presented to adapt the nonlinear multivariable system with noises and time delays and with changed system parameter after a constant time. The proposed PID type nonlinear multivariable self-tuning method using neural network is effective compared with the conventional direct multivariable adaptive controller using neural network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.549-551
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• 2017

There are currently various file encryption systems and applications for encryption and storage of file on disk. However, the existing file encryption solutions handle encryption and decryption all at once by file or directory. In this study, we propose a system call supporting partial encryption function of the file. The user sets the partial encryption of the file by using system call interface, and writes the contents. And then the data is encrypted and stored on the disk. Also if the user sets the decryption and reads the data, the necessary part of data is decrypted by applying the user setting. According to the user setting, only the necessary part is encrypted and stored on a storage medium. As a result, the information in a secret level can be saved efficiently and securely.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.3
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• pp.40-47
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• 2012

In dual-hop relaying systems, the conventional partial relay selection is based on the channel information only for the first hop. On the other hand, the efficient partial relay selection is based on the channel information for the hop with the minimum of the average channel powers for the first and second hops at each end-to-end link since the correlation coefficient between the end-to-end link quality and the link quality of the hop with the minimum of the average channel powers for the first and second hops is larger than that between the end-to-end link quality and the link quality of the other hop. In this paper, the outage probability of the conventional partial relay selection and the efficient partial relay selection in dual-hop decode-and-forward relaying systems is analyzed for non-identically distributed Rayleigh fading channels. Through numerical investigation, the outage performance of the efficient partial relay selection is compared with the outage performances of the conventional partial relay selection and the best relay selection based on all the channel information for the first and second hops.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.59-61
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• 1998

광범위한 범위에서 사용되고 있는 실시간 시스템을 위하여 실시간 커널의 사용은 필수적이다. 본 논문에서는 다양한 분야에서 사용될 수 있는 이식성이 높고, 목적 시스템에 필용한 커널 서비스만을 선택하여 커널의 크기를 조절할 수 있는 실시간 커널의 개발하였다. 이 커널은 병렬 커널로의 확작성을 고려하여 LINDA 개념을 기초로 하여 개발되었는데. 기존에 개발된 실시간 커널 HLINDA와 비교하였을 때 보다 좋은 성능을 보여주었다. 또한 시스템 기초화 부분과 콘텍스트 스위치 등, 몇 부분을 제외한 전 커널의 95%이상을 C-언어로 작성하여 높은 이식성을 갖고 있다.