• Journal of KIISE:Computing Practices and Letters
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• v.16 no.8
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• pp.868-872
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• 2010

Many embedded Java systems are equipped with limited memory, which can constrain the code cache size provided for Java just-in-time compilation, affecting the Java performance. This paper proposes expanding the limited code cache when it is full, by saving the machine code for some methods in the code cache into the file system of the permanent storage and reloading it to the code cache when they are re-invoked later. This is applying the client ahead-of-time compilation during the execution time for the purpose of enlarging the code cache. Our experimental results indicate that the proposed execution method can improve the performance by as much as 1.6 times compared to the conventional method, when the code cache size is reduced by half.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.542-546
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• 2008

Recently dual-port SDRAM (DPSDRAM) architecture tailored for dual-processor based mobile embedded systems has been announced where a single memory chip plays the role of the local memories and the shared memory for both processors. In order to maintain memory consistency from simultaneous accesses of both ports, every access to the shared memory should be protected by a synchronization mechanism, which can result in substantial access latency. We propose two optimization techniques by exploiting the communication patterns of target applications: lock-priority scheme and static-copy scheme. Further, by dividing the shared bank into multiple blocks, we allow simultaneous accesses to different blocks thus achieve considerable performance gain. Experiments on a virtual prototyping system show a promising result - we could achieve about 20-50% performance gain compared to the base DPSDRAM architecture.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.674-682
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• 2003

Ship autonomous navigation is designated as what computerizes mental faculties possessed of navigation experts, which are building navigation plans, grasping the situation, forecasting the fluctuation, and coping with the situation. An autonomous navigation system, which consists of several subsystems such as navigation system, a collision avoidance system, several data fusion systems, and a motion control system, is based on an intelligent control architecture for the sake of integrating the systems. The motion control system, which is one of the most essential system in autonomous navigation system, controls its propulsion and steering gears to move the ship satisfying its hydrodynamic characteristics. This paper is the study on the ship movement control system and its implementation which are totally developed and run on virtual-world system. Receiving the high-level control values such as a waypoint presented from the collision avoidance system, the motion control system generates them to low-level control values for propulsion and steering devices. In the paper, we develop a ship motion controller using Oldenburger's theory based on mathematical fundamentals, and simulate it with various scenarios in order to verify its performance.

• Journal of Internet Computing and Services
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• v.14 no.2
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• pp.61-71
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• 2013

Until now, there have been various studies against Internet worms. Most of intrusion detection and prevention systems against Internet worms use detection rules, but these systems cannot respond to new Internet worms. For this reason, a malicious process control system which uses the fact that Internet worms multicast malicious packets was proposed. However, the greater the number of servers to be protected increases the cost of the malicious process control system, and the probability of detecting Internet worms attacking only some predetermined IP addresses is low. This paper presents a security framework that can reduce the cost of the malicious process control system and increase the probability of detecting Internet worms attacking only some predetermined IP addresses. In the proposed security framework, virtual machines are used to reduce the cost of control servers and unused IP addresses are used to increase the probability of detecting Internet worms attacking only some predetermined IP addresses. Therefore the proposed security framework can effectively respond to a variety of new Internet worms at lower cost.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.6
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• pp.2049-2068
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• 2021

AI combined with NLP techniques has promoted the use of Virtual Assistants and have made people rely on them for many diverse uses. Conversational Agents are the most promising technique that assists computer users through their operation. An important challenge in developing Conversational Agents globally is transferring the groundbreaking expertise obtained in English to other languages. AI is making it possible to transfer this learning. There is a dire need to develop systems that understand secular languages. One such difficult language is Hindi, which is the fourth most spoken language in the world. Semantic similarity is an important part of Natural Language Processing, which involves applications such as ontology learning and information extraction, for developing conversational agents. Most of the research is concentrated on English and other European languages. This paper presents a Corpus-based word semantic similarity measure for Hindi. An experiment involving the translation of the English benchmark dataset to Hindi is performed, investigating the incorporation of the corpus, with human and machine similarity ratings. A significant correlation to the human intuition and the algorithm ratings has been calculated for analyzing the accuracy of the proposed similarity measures. The method can be adapted in various applications of word semantic similarity or module for any other language.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.10
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• pp.261-268
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• 2021

Cloud computing is a computing paradigm in which users can utilize computing resources in a pay-as-you-go manner. In a cloud system, resources can be dynamically scaled up and down to the user's on-demand so that the total cost of ownership can be reduced. The Modeling and Simulation (M&S) technology is a renowned simulation-based method to obtain engineering analysis and results through CAE software without actual experimental action. In general, M&S technology is utilized in Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD), Multibody dynamics (MBD), and optimization fields. The work procedure through M&S is divided into pre-processing, analysis, and post-processing steps. The pre/post-processing are GPU-intensive job that consists of 3D modeling jobs via CAE software, whereas analysis is CPU or GPU intensive. Because a general-purpose desktop needs plenty of time to analyze complicated 3D models, CAE software requires a high-end CPU and GPU-based workstation that can work fluently. In other words, for executing M&S, it is absolutely required to utilize high-performance computing resources. To mitigate the cost issue from equipping such tremendous computing resources, we propose HEMOS-Cloud service, an integrated cloud and cluster computing environment. The HEMOS-Cloud service provides CAE software and computing resources to users who want to experience M&S in business sectors or academics. In this paper, the economic ripple effect of HEMOS-Cloud service was analyzed by using industry-related analysis. The estimated results of using the experts-guided coefficients are the production inducement effect of KRW 7.4 billion, the value-added effect of KRW 4.1 billion, and the employment-inducing effect of 50 persons per KRW 1 billion.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.297-302
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• 2008

In case of display a lot of information from mobile devices, those systems are being developed that display the information from mobile devices on remote devices such as TV using the mobile devices as remote controllers because it is difficult to display a lot of information on mobile devices due to their limited bandwidth and small screen sizes. A lot of cost is required to design and develop interfaces for these systems corresponding to each of remote display devices. In this paper, a mobile environment based remote display system for displays at real times is proposed for continuous monitoring of status data for unique 'Mote IDs'. Also, remote data are collected and monitored through sensor network devices such as ZigbeX by applying status perception based remote displays at real times through processing ubiquitous computing environment data, and remote display applications at real times are implemented through PDA wireless mobiles. The system proposed in this paper consists of a PDA for remote display and control, mote embedded applications programming for data collections and radio frequency, server modules to analyze and process collected data and virtual prototyping for monitoring and controls by virtual machines. The result of the implementations indicates that this system not only provides a good mobility from a human oriented viewpoint and a good usability of accesses to information but also transmits data efficiently.

• Journal of Internet Computing and Services
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• v.15 no.5
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• pp.107-121
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• 2014

Distributed systems are collection of physically distributed computers linked by a network. General use of wired/wireless Internet enables users to make use of distributed service anytime and anywhere. The explosive growth of distributed services strongly requires functional verification of services as well as verification of non-functional elements such as service quality. In order to verify distributed services it is necessary to build a test environment for distributed systems. Because, however, distributed systems are composed of physically distributed nodes, efforts to construct a test environment are required more than those in a test environment for a monolithic system. In this paper we propose a test framework to verify functional and non-functional features of distributed systems. The suggested framework automatically generates test cases through the message sequence charts, and includes a test driver composed of the virtual nodes which can simulate the physically distributed nodes. The test result can be checked easily through the various graphs and the graphical user interface (GUI). The test framework can reduce testing efforts for a distributed system and can enhance the reliability of the system.

• The Transactions of the Korea Information Processing Society
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• v.13 no.2
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• pp.48-59
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• 2024

As functions that support virtualization on their own in hardware are developed, user applications having various workloads are operating efficiently in the virtualization system. SR-IOV is a virtualization support function that takes direct access to PCI devices, thus giving a high I/O performance by minimizing the need for hypervisor or operating system interventions. With SR-IOV, network I/O acceleration can be realized in virtualization systems that have relatively long I/O paths compared to bare-metal systems and frequent context switches between the user area and kernel area. To take performance advantages of SR-IOV, network resource management policies that can derive optimal network performance when SR-IOV is applied to an instance such as a virtual machine(VM) or container are being actively studied.This paper evaluates and analyzes the network performance of SR-IOV implementing I/O acceleration is compared with Virtio in terms of 1) network delay, 2) network throughput, 3) network fairness, 4) performance interference, and 5) multi-network. The contributions of this paper are as follows. First, the network I/O process of Virtio and SR-IOV was clearly explained in the virtualization system, and second, the evaluation results of the network performance of Virtio and SR-IOV were analyzed based on various performance metrics. Third, the system overhead and the possibility of optimization for the SR-IOV network in a virtualization system with high VM density were experimentally confirmed. The experimental results and analysis of the paper are expected to be referenced in the network resource management policy for virtualization systems that operate network-intensive services such as smart factories, connected cars, deep learning inference models, and crowdsourcing.

• KIISE Transactions on Computing Practices
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• v.23 no.4
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• pp.262-267
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• 2017

RTEMS is a real-time operating system using a GPLv2-based license, and is used in the aerospace industry, such as satellites. It is difficult to build a development environment for these special-purpose systems because of problems related to the hardware platform. This can be resolved by applying virtualization technology. However, increased execution time and performance degradation due to virtualization overhead can change timing behavior of real-time application, and needs to be minimized. In this paper, we aim to implement the network device driver of RTEMS for the standardized virtual network device called virtio in order to effectively utilize RTEMS in a virtualized environment. In addition, we describe the process of submitting implemented driver to the RTEMS community for contributing open source software and reflecting the various requirements of the community.