• Journal of KIISE:Computer Systems and Theory
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• v.28 no.9
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• pp.424-433
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• 2001

The cyclic debugging approach often fails for message passing parallel programs because they non-deterministic characteristics due to message race conditions. This paper identifies the MPI events that affect non-deterministic executions, and then converts the concurrent execution to the sequential one that is controlled in order to make it equivalent to a reference execution by keeping their orders of events in two executions identical. This paper also presents an efficient algorithm for the causal distributed breakpoint which is initiated by any sequential breakpoint in one process, and restores each process to the earliest state that reflects all events that happened causally before the sequential breakpoint. So a cyclic debugging approach can be used in debugging MPI parallel programs as like as in debugging sequential programming environments.

• Journal of Digital Contents Society
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• v.17 no.3
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• pp.143-155
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• 2016

In this study, we focused on the importance of politicians' voices in sending a message. Different factors for a voice may play different roles in sending a message and affect message recipients' responsiveness, understanding, and so on. For this reason, it can be said that an analytical study on voices in sending a diversity of messages is a meaningful attempt. We took interest in politicians' voices because we determined that a voice should be very important to politicians frequently sending a message through speech to the nation and others. This study aimed to investigate the voices of politicians, who represent their nation. We intended to select politicians representing ROK(Republic of Korea; South Korean) and USA(United States of America), choose representative speeches to the nation, make a comparative analysis of their voices in the speeches, and draw implications. We analyzed a total of eight voices - four ROK politicians and four USA ones, male and female - to characterize them and suggest guidelines for a voice with clearer message delivery. We analyzed the politicians' voices on the basis of such vocal properties as vocal pitch, accuracy of pronunciation, resonance, and intonation variation and found that the ROK politicians were somewhat poorer at utilizing their voice than the US ones. In particular, they were remarkably poorer at accurate pronunciation, which exerts a significant impact on message passing.

• International Journal of CAD/CAM
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• v.4 no.1
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• pp.47-53
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• 2004

The subdivision surface is the limit of recursively refined polyhedral mesh. It is quite intuitive that the multi-resolution feature can be utilized to simplify generation of NC (Numerical Control) tool paths for rough machining. In this paper, a new method of parallel NC tool path generation for subdivision surfaces is presented. The basic idea of the method includes two steps: first, extending G-Buffer to a strip buffer (called S-Buffer) by dividing the working area into strips to generate NC tool paths for objects of large size; second, generating NC tool paths by parallel implementation of S-Buffer based on MPI (Message Passing Interface). Moreover, the recursion depth of the surface can be estimated for a user-specified error tolerance, so we substitute the polyhedral mesh for the limit surface during rough machining. Furthermore, we exploit the locality of S-Buffer and develop a dynamic division and load-balanced strategy to effectively parallelize S-Buffer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.863-870
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• 1993

A new methodology of multimedia data composition generated SRT(Synchronization Relation Tree) dynamically after user composing multimedia date by using high level user interface, and processes message passing protocols to adjust multimedia data temporal composition. In this paperl we propose SRT generating algorithm which transfer user defined timeline diagram to SRT dynamically. SRT generating algorithm is to use divide and conquer methodology and recurvise programming. And prove that it generates and type of multimedia date compositon to SRT.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.23-34
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• 2005

In a large scale parallel computation, failures of some nodes or communication links end up with waste of computing resources, Several fault-tolerant MPI libraries have been proposed so far, but the programs written by using such libraries have a portability problem since fault-tolerant features are not supported by the MPI standard yet, In this paper, we propose an application-level fault-tolerant linear system solver that uses the asynchronous iteration algorithm and the standard MPI functions only, which does not have a portability problem and is more efficient by adopting a simplified recovery mechanism.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.732-734
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• 1998

본 논문에서는 메시지 전달을 기반으로 하는 병렬 분산 시스템에 고장 감내 기능을 추가하기 위한 고장 감내 기법과, 고장 복구에 따른 프로세서들간의 일관성 유지방법을 제안하였다. 메시지 전달을 기반으로 하는 병렬 컴퓨터 시스템상에서 응용 프로그램들은 수많은 노드들에 분산 배치되어 수행이 되는데, 그중 어느 한 노드 또는 작업 중인 프로세서가 고장을 일으킨다면 이로 인하여 전체 응용 프로그램이 중단 될 것이다. 이러한 문제를 해결하기 위하여 고장 감내 기능 추가가 필요하며, 그 방법으로서 동일한 작업을 수행하는 프로세서를 서로 다른 노드상에 이중화하여 하나의 프로세서에 고장이 발생하더라도 계속 작업중인 예비 프로세서를 이용함으로써 전체 응용 프로그램이 아무런 영향을 받지 않도록 하였다. 그리고 이를 MPI상에 서브 모듈로써 설계하고 구현하였다.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.744-747
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• 1997

High performance digital computer technology enables the digital computer-based controllers to replace traditional analog controllers used for factory automations. This replacement, however, brings up the side effects caused by discrete quantization and non-real-time execution of control softwares. This paper describes the structure of real-time simulator and controller that can be used for design and verification of real-time digital controllers. The virtual machine concept adopted by real-time simulator make the proposed simulator be independent from the specific hardware platforms. The proposed system can also be used in the loosely coupled distributed environments connected through local area network using real-time message passing algorithm and virtual data table based on the shared memory mechanism.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.115-121
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• 1999

Advanced digital computer technology enables the computer-based controllers to replace the traditional analog controllers used in factory automations. This replacement, however, brings up the side effects caused by the quantization error and non-real-time execution of control software. This paper describes the structure of real-time simulator and controller that can be used for design and verification of real-time digital controllers. The virtual machine concept adopted by the proposed real-time simulator makes the proposed simulator be independent from the specific hardware platforms. The proposed system can also be used in the loosely coupled distributed environments connected through local area network using real-time message passing algorithm and virtual data table based on the shared memory mechanism.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.659-679
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• 2015

Distributed applications are composed of multiple nodes, which exchange information with individual nodes through message passing. Compared with traditional applications, distributed applications have more complex behavior patterns because a large number of interactions and concurrent behaviors exist among their distributed nodes. Thus, it is difficult to detect anomalous behaviors and determine the location and scope of abnormal nodes, and some attacks and misuse cannot be detected. To address this problem, we introduce a method for detecting anomalous behaviors based on process algebra. We specify the architecture of the behavior detection model and the detection algorithm. The anomalous behavior detection and analysis demonstrate that our method is a good discriminator between normal and anomalous behavior characteristics of distributed applications. Performance evaluation shows that the proposed method enhances efficiency without security degradation.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.148-151
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• 2007

The Korea Meteorological Administration has been operating a tsunami warning system which is based on tsunami scenario database for the East Sea. Recently, the tsunami scenario database for the Yellow sea and the East China sea is also generated so that the tsunami warning system is extended to the whole Korean seas. Tsunami scenario database includes tsunami arrival times and heights generated by performing huge numbers of tsunami propagation simulations. A leap-frog method for shallow water equation is used for the simulation. The simulation code is parallellized via Message Passing Interface and has run on Cray X1E.