• The Korean Journal of Applied Statistics
• /
• v.27 no.2
• /
• pp.249-261
• /
• 2014

Ever increasing "Big data" can only be effectively processed by parallel computing. Parallel computing refers to a high performance computational method that achieves effectiveness by dividing a big query into smaller subtasks and aggregating results from subtasks to provide an output. However, it is well-known that parallel computing does not achieve scalability which means that performance is improved linearly by adding more computers because it requires a very careful assignment of tasks to each node and collecting results in a timely manner. Hadoop is one of the most successful platforms to attain scalability. In this paper, we propose a measurement for Hadoop optimization by utilizing a Lorenz curve which is a proxy for the inequality of hardware resources. Our proposed index takes into account the intrinsic overhead of Hadoop systems such as CPU, disk I/O and network. Therefore, it also indicates that a given Hadoop can be improved explicitly and in what capacity. Our proposed method is illustrated with experimental data and substantiated by Monte Carlo simulations.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.1
• /
• pp.17-23
• /
• 2014

Graphics processing units (GPUs) are ideal for solving problems involving parallel data computations. In this study, the GPU is used for effectively carrying out a multi-body dynamic simulation with particle dynamics. The Hilber-Hushes-Taylor (HHT) implicit integration algorithm is used to solve the integral equations. For detecting collisions among particles, the spatial subdivision algorithm and discrete-element methods (DEM) are employed. The developed program is verified by comparing its results with those of ADAMS. The numerical efficiencies of the serial program using the CPU and the parallel program using the GPU are compared in terms of the number of particles, and it is observed that when the number of particles is greater, more computing time is saved by using the GPU. In the present example, when the number of particles is 1,300, the computational speed of the parallel analysis program is about 5 times faster than that of the serial analysis program.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.6
• /
• pp.507-515
• /
• 2017

Flexible multibody simulations are widely used in the industry to design mechanical systems. In flexible multibody dynamics, deformation coordinates are described either relatively in the body reference frame that is floating in the space or in the inertial reference frame. Moreover, these deformation coordinates are generated based on the discretization of the body according to the finite element approach. Therefore, the formulation of the flexible multibody system always deals with a huge number of degrees of freedom and the numerical solution methods require a substantial amount of computational time. Parallel computational methods are a solution for efficient computation. However, most of the parallel computational methods are focused on the efficient solution of large-sized linear equations. For multibody analysis, we need to develop an efficient formulation that could be suitable for parallel computation. In this paper, we developed a subsystem synthesis method for a flexible multibody system and proposed efficient parallel computational schemes based on the OpenMP API in order to achieve efficient computation. Simulations of a rotating blade system, which consists of three identical blades, were carried out with two different parallel computational schemes. Actual CPU times were measured to investigate the efficiency of the proposed parallel schemes.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.7
• /
• pp.507-517
• /
• 2003

A single fiber failure in mesh-based WDM networks may result in the loss of a large number of data. To remedy this problem, an efficient restoration algorithm for a single fiber failure in the mesh- based WDM network is necessary. We propose a new algorithm for restoration scheme in WDM networks and compare it with previous schemes. Path restoration and link restoration are two representative restoration schemes which deal with only a single link failure. In this paper, we propose two kinds of efficient restoration scheme. In the proposed schemes the restoration path for each link failure is not secured. The mesh network is decomposed into a number of small loops. In one algorithm, any link failure in a certain loop is regarded as the failure of the loop and the restoration lightpath is selected by detouring the failed loop. In another scheme any link failure in a certain loop is restored within the loop. We compare performance of the proposed schemes with conventional path restoration scheme and link restoration scheme. Simulation results show that CPU time in the proposed schemes decreases compared with that in path restoration scheme and link restoration scheme, although total wavelength mileage usage increases by 10% to 50%.

• Computational Structural Engineering
• /
• v.10 no.4
• /
• pp.217-228
• /
• 1997

The high precision analysis by the p-version of the finite element method are fairly well established as highly efficient method for linear elastic problems, especially in the presence of stress singularity. It has been noted that the merits of the p-version are accuracy, modeling simplicity, robustness, and savings in user's and CPU time. However, little has been done to exploit their benefits in elasto-plastic analysis. In this paper, the p-version finite element model is proposed for the materially nonlinear analysis that is based on the incremental theory of plasticity using the constitutive equation for work-hardening materials, and the associated flow rule. To obtain the solution of nonlinear equation, the Newton-Raphson method and initial stiffness method, etc are used. Several numerical examples are tested with the help of the square plates with cutout, the thick-walled cylinder under internal pressure, and the circular plate with uniformly distributed load. Those results are compared with the theoretical solutions and the numerical solutions of ADINA

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.2
• /
• pp.39-48
• /
• 2014

In this paper, we propose an efficient dynamic workload balancing strategy which improves the performance of high-performance computing system. The key idea of this dynamic workload balancing strategy is to minimize execution time of each job and to maximize the system throughput by effectively using system resource such as CPU, memory. Also, this strategy dynamically allocates job by considering demanded memory size of executing job and workload status of each node. If an overload node occurs due to allocated job, the proposed scheme migrates job, executing in overload nodes, to another free nodes and reduces the waiting time and execution time of job by balancing workload of each node. Through simulation, we show that the proposed dynamic workload balancing strategy based on CPU, memory improves the performance of high-performance computing system compared to previous strategies.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.2
• /
• pp.11-19
• /
• 2020

Modern GPU can execute general purpose computation on the graphic processing unit, and provide high performance by exploiting many core on GPU. To run AES algorithm efficiently, parallel computational resources are required. However, computational resource of CPU architecture are not enough to cryptographic algorithm such as AES whereas GPU architecture has mass parallel computation resources. Therefore, this paper reduce the time to execute AES by employing parallel computational resource on GPGPU. Unfortunately, AES cannot utilize computational resource on GPGPU since it isn't suitable to GPGPU architecture. In this paper, IPC based dynamic SM management technique are proposed to efficiently execute AES on GPGPU. IPC based dynamic SM management can increase and decrease the number of active SMs by using IPC in run-time. According to simulation results, proposed technique improve the performance by increasing resource utilization compared to baseline GPGPU architecture. The results show that AES improve the performance by 41.2% on average.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.321-327
• /
• 2006

This paper presents low power and high frequency design of instructions using ad-hoc techniques at transistor level for full custom and semi-custom ASIC(Application Specific Integrated Circuit) designs. The proposed design has been verified at high level using Verilog-HDL and simulated using ModelSim for the logical correctness. It is then observed at the layout level using LASI using $0.25{\mu}m$ technology and analyzed for timing characteristic under Win-spice simulation environment. The result shows the significant reduction up to $35\%$ in the power consumption by any general purpose processor like RISC or CISC. A significant reduction in the propagation delay is also observed. increasing the frequency for the fetch and execute cycle for the CPU, thus increasing the overall frequency of operation.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.2
• /
• pp.343-350
• /
• 2010

In the existing design of web server architecture, data encryption technique is used to keep the reliability, stability, and safety of web service. But the use of data encryption technique wastes the work of cpu while decreasing throughput of web server and increasing average response time so that it shows negative effect on the capacity of web application server. Also, the latest web applications require security and safety for the safe internet communication. Therefore, this paper suggests the improved web server which uses thread pool and Non-blocking I/O adding new web service modules to the existing web server for the safe web service, provides reliability and safety to show the safe web service capacity. And we compare and evaluate the safety and capacity through experiment on the existing traditional Tomcat based web server and the proposed system to evaluate the safety and capacity of the proposed web server system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.4
• /
• pp.549-560
• /
• 1993

A simple closed form approximation is developed by a new approach presented in this paper for the microstrip surface dyadic Green's function which arises in the problem of an electric current point source on an infinite planar grounded dielectric substrate. This closed form approximation includes the effects of the space wave, the surface wave and their coupling within the transition region near the source, and remains accurate as near as $0.1{\pi}_1$ from the source point for a substrate thickness as large as $0.04{\pi}_1$, where, ${\pi}_1$, is the free space wavelength, This result can significantly facilitate the rigorous moment method analysis of microstrip antenna arrays on relatively this substrates of practical interest. Numerical results illustrating the accuracy of the closed form approximation are presented and CPU times associated with some mutual impedance calculations are also included.