• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.7
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• pp.52-60
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• 2010

In this paper, we propose a dynamic power management framework for multi-core systems. We reduced the power consumption of multi-core processors such as Intel Centrino Duo and ARM11 MPCore, which have been used at the consumer electronics and personal computer market. Each processor uses a different technique to save its power usage, but there is no embedded multi-core processor which has a precise power control mechanism such as dynamic voltage scaling technique. The proposed dynamic power management framework is suitable for smart phones which have an operating system to provide multi-processing capability. Basically, our framework follows an intuitive idea that reducing the power consumption of idle cores is the most effective way to save the overall power consumption of a multi-core processor. We could minimize the energy consumption used by idle cores with application-targeted policies that reflect the characteristics of active workloads. We defined some properties of an application to analyze the performance requirement in real time and automated the management process to verify the result quickly. We tested the proposed framework with popular processors such as Intel Centrino Duo and ARM11 MPCore, and were able to find that our framework dynamically reduced the power consumption of multi-core processors and satisfied the performance requirement of each program.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.303-310
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• 2013

As the role of software increases in computing environments, issues in software security become more important problems. Dynamic taint analysis is a technique to trace and manage tainted data originated from unreliable sources during the execution of a program. This analysis can be applied to software security verification as well as software behavior understanding, testing unexpected errors, or debugging. In the previous researches, they focussed only to show the analysis results of dynamic taint analysis, and they did not logically describe propagation process of tainted data and analysis procedures. So, there were difficulties in understanding the analysis procedures or applying to other analysis. In this paper, by theoretically describing the analysis procedure, we logically show how the propagation process of tainted data can be traced, and present a theoretical model for dynamic taint analysis. In addition, we verify the correctness of the proposed model by implementing an analyser, and show that propagation of tainted data can be traced by the model. The proposed model can be applied to understand the analysis procedures of data flows in dynamic taint analysis, and can be used as an base knowledge for designing and implementing analysis method, which applies such analysis method.

• The KIPS Transactions:PartA
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• v.12A no.6 s.96
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• pp.557-562
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• 2005

Throughput and latency of interconnection network are important factors of the performance of multiprocessor systems. The dual-link CC-NUMA architecture using point-to-point unidirectional link is one of the popular structures in high-end commercial systems. In terms of optimal path between nodes, several paths exist with the optimal hop count by its native multi-path structure. Furthermore, transaction latency between nodes is affected by congestion of links on the transaction path. Hence the transaction latency may get worse if the transactions make a hot spot on some links. In this paper, I propose a dynamic transaction routing algorithm that maintains the balanced link utilization with the optimal path length, and I compare the performance with the fixed path method on the dual-link CC-NUMA systems. By the proposed method, the link competition is alleviated by the real-time path selection, and consequently, dynamic transaction algorithm shows a better performance. The program-driven simulation results show $1{\~}10\%$ improved fluctuation of link utilization, $1{\~}3\%$ enhanced acquirement of link, and $1{\~}6\%$ improved system performance.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.11a
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• pp.29-36
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• 2004

많은 기능을 수행하는 네트워크 프로그램은 그 기능 만큼의 명령어들과 명령어 인자들을 주고 받게 되다. 수신된 명령어에 대한 처리는 $"IF\~ELSE"$ 같은 순차적인 비교구문을 사용하거나 자바 RMI같은 원격 메소드 호출방식을 사용하고 있다. 그러나 많은 명령어들을 매번 순차적인 방식으로 비교하는 것과 원격 메소드를 설계하는 방식은 그 구현 및 유지보수에 많은 어려움을 유발하고 있다. 본 논문의 목적은 명령어 수신부와 실행부에 대한 컴포넌트를 개발하여 프로그램 개발 및 유지보수에 들어가는 노력을 줄이고 프로그램의 수행성능을 향상시키기 위한 컴포넌트 개발에 있다.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.11-22
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• 1998

An axisymmetric shell element which includes the effects of the meridional and circumferential cable prestresses is developed. It is coded for personal computer by the maximum use of axisymmetic properties and the dynamic analysis is performed under the seismic exitations. A ring element is used to fully utilize the characteristics of the axisymmetric shell. The eigenvalue solutions using 20 elements under the initial prestresses are in good agreement with the exact solutions. The results of the seismic analysis show that the radial deflection under the meridional prestress is a little larger than that under the circumferential prestress. The finite element model developed in this study can be very useful to the design applications.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.7
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• pp.451-460
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• 2013

In order to achieve high test coverage, it is usual to generate test data using various techniques including symbolic execution, data flow analysis or constraints solving. Recently, a technique for automated test data generation that fulfills high coverage effectively without those sophisticated means has been proposed. However, the technique shows its weakness in the generation of test data that leads to high coverage for programs having branch conditions where different memory locations are binded during execution. For certain programs with flag conditions, in particular, high coverage can not be achieved because specific branches are not executed. To address the problem, this paper presents dynamic branch coverage criteria and a test data generation technique based on the notion of dynamic branch. It is shown that the proposed technique compared to the previous approach is more effective by conducting experiments involving programs with flag conditions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.395-404
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• 2005

This paper presents a reliable numerical procedure for nonlinear time-history analysis of space steel frames subjected to dynamic loads. Geometric nonlinearities of member (P-$\delta$) and frame (P-$\Delta$) are taken into account by the use of stability functions in framed stiffness matrix formulation. The gradual yielding along the member length and over the cross section is included by using a tangent modulus concept and a softening plastic hinge model based on the New-Orbison yield surface. A computer program utilizing the average acceleration method for the integration scheme is developed to numerically solve the equation of motion of framed structure formulated in an incremental form. The results of several numerical examples are compared with those derived from using beam element model of ABAQUS program to illustrate the accuracy and the computational efficiency of the proposed procedure.

• Computational Structural Engineering
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• v.7 no.1
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• pp.69-81
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• 1994

This paper summarizes a dynamic analysis of the shallow circular arches under dynamic loading, considering the geometric nonlinearity. The major emphasis is placed on the development of computer program, which is utilized for the analysis of the nonlinear dynamic behavior and for the evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and a finite element analysis procedure is used to solve the dynamic equation of motion. A circular arch subject to normal step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of arches are estimated using the non-dimensional time, load and shape parameters and the results are also compared with those from the linear analysis. It is found that geometric nonlinearity plays and important role in the analysis of shallow arches and the probability of buckling failure is getting higher as arches become shallower.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.892-897
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• 2017

As the weapon system SW development and management manual of the DAPA, which is the regulation for the overall weapon system SW development, is revised, the level and scope of SW reliability test are upgraded to improve the reliability and quality of SW. It is a big burden for SW developers. In particular, the dynamic test requires a schedule and manpower required to implement the weapon system SW, and should be performed every time the source code changes, not just one time. In this paper, we propose a regression test automation program(VectorCast Environment Manager) that performs a dynamic test using VectorCast, a dynamic test tool, and then performs a regression test automatically by minimizing human intervention in the regression test of dynamic test due to the change of the source code.

• Journal of the KSME
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• v.22 no.6
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• pp.447-451
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• 1982

NASTRAN은 모든 구조물 특히 대형 구조물의 정적 해석(static analysis)뿐 아니라 동적 해석, 구조물과 주변 유체 유동과의 관계, seismic analysis, acoustic analysis등 광범위하게 사용되어 질 수 있는 전산 프로그램이다. KAIST에서는 NASTRAN을 보다 효과적으로 활용하기 위하여 pre-processor, postprocess의 개발에 노력하고 있으며 특히 NASTRAN 해석의 결과를 가시화 하기 위하여 computer graphics를 위한 전산 프로그램인 MOVIE-BYU를 NASTRAN과 연결 시켜 사용하려 시도하고 있다.