• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.121-129
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• 2022

In this paper, the virtual environment using rack server type HPC and 3U VPX server type HPC was applied and tested to the basic functions of the Jangbogo-III class submarine combat system developed for the first time in Korea. Based on this test results, the possibility of applying virtualization to the domestic submarine combat system to be developed in the future is confirmed. Existing studies have been limited to deriving applicable virtualization solutions through simple performance analysis of virtualization solutions or applying virtualization to some functions of the surface ship combat system, but in this paper, the application of virtualization is expanded to the submarine combat system through testing.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.385-392
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• 2022

As energy-saving techniques based on human behavior patterns have recently become an issue, the occupant-centered control system is adopted for estimating personal preference of indoor environment and optimizing environmental comfort and energy consumption. Accordingly, IoT devices have been used to collect indoor environmental quality (IEQ) data and personal data. However, the need to safely collect and manage data has been emerged due to cybersecurity issues. Therefore, this paper aims to present a framework that can safely transmit occupant-centered data collected from IoT to a private blockchain server using Hyperledger fabric. In the case study, the minimum value product of the mobile application and smartwatch application was developed to evaluate the usability of the proposed blockchain-based occupant-centered data collection framework. The results showed that the proposed framework could collect data safely and hassle-free in the daily life of occupants. In addition, the performance of the blockchain server was evaluated in terms of latency and throughput when ten people in a single office participated in the proposed data collection framework. Future works will further apply the proposed data collection framework to the building management system to automatically collect occupant data and be used in the HVAC system to reduce building energy consumption without security issues.

• Journal of Wind Energy
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• v.2 no.1
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• pp.90-96
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• 2011

The purpose of this paper is to describe the control system for optimal performance of 2MW gearless PMSG wind turbine system, and to afford some techniques of the algorithm selection and design optimization of the wind turbine control system through analysis of load calculation and control characteristic. Wind turbine control system is composed of the main control system and remote control and monitoring system. The main control system is industrial PC based controller, and the remote control and monitoring system is a server based computer system. The main control system has a supervisory control of the wind turbine with operation procedures and power-speed control through the torque control by pitch angle. There are some applications to optimize the wind turbine system at the starting mode with increasing of rotor speed, and cut-in operating mode to prevent trundling cut-in and cut-out, a gain scheduling of pitch PID controller, torque scheduling and limitation of generation power by temperature limitation or remote command by remote control and monitoring system. Also, the server operation program of the remote control and monitoring system and the design of graphical display are described in this paper.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.179-186
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• 2013

PACS is a medical system for digital medical images, and PACS expand to web-based service using public network, DICOM files should be protected from the man-in-the-middle attack because they have personal medical record. To solve the problem, we designed flexible secure transmission system using IPSec and adopted to a web-based three-dimensional medical image system. And next, we performed the performance evaluation changing integrity and encryption algorithm using DICOM volume dataset. At that time, combinations of the algorithm was 'DES-MD5', 'DES-SHA1', '3DES-MD5', and '3DES-SHA1, and the experiment was performed on our test-bed. In experimental result, the overall performance was affected by encryption algorithms than integrity algorithms, DES was approximately 50% of throughput degradation and 3DES was about to 65% of throughput degradation. Also when DICOM volume dataset was transmitted using secure transmission system, the network performance degradation had shown because of increased packet overhead. As a result, server and network performance degradation occurs for secure transmission system by ensuring the secure exchange of messages. Thus, if the secure transmission system adopted to the medical images that should be protected, it could solve server performance gradation and compose secure web PACS.

• The Journal of Korean Association of Computer Education
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• v.18 no.3
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• pp.115-124
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• 2015

In this paper, we introduce a web-based scheduling toolkit(GridTool2), which can run simulation of scheduling algorithm in grid system. And we suggest new algorithms which apply additional communication costs to the existing MinMin and Suffrage scheduling algorithms. Since GridTool2 runs in web environment using server and database, it does not require a separate compiler or runtime environment. The GridTool2 allows variables such as communication costs on the web for performance evaluation, and shows simulation results on the web page. The new algorithm with communication costs was tested using GridTool2 to check for performance improvements. The results revealed that the new algorithm showed better performance as more workloads were incorporated to the system.

• The KIPS Transactions:PartA
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• v.12A no.7 s.97
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• pp.613-620
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• 2005

To provide reliable differentiated service for internet clients, many studies on differentiated service are widely done. According to the types of the request of the clients in cluster-based web systems, SLA (Service Level Agreement) between service provider and the clients is considered. In this Paper, we study primary-backup web switch in the web systems that distribute the request of clients to each of web servers and also study performance isolation and admission control schemes of heterogeneous web systems which distinguish the servers into each different function domains. We analyze the availability, the response time and the performance of admission control through various simulated experiments on the proposed web systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.69-75
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• 2016

The performance of a web application is an essential issue to provide high quality of the services in interactive web environments. On a sudden increase in traffic in a very short span of time, the servers became CPU starved and would become unresponsive. This would lead to a bad experience for the clients of web service. This paper deals with the effects of two configurable software settings of J2EE application servers: the maximum size of the thread pool and the maximum size of database connection pool. In order to figure out the optimum configuration value, this paper builds experimental evaluation method for web performance analysis. Finally, a case study related with the proper experimental method is presented with performance result.

• Journal of Internet Computing and Services
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• v.1 no.1
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• pp.27-34
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• 2000

Recently, the use of Geographic Information System in each field of our society is on the increase according to the development of the Internet. But, thereis a problem of the user access latencies, the network traffic, and the server overload in Internet Geographic Information System because spatial data are transferred in large volumes. In this paper, we propose a cache algorithm on client side to solve the above problems. The proposed algorithm demonstrates the performance improvement over known studies by utilizing unit time and spatial proximity. In addition, this paper conducts a performance evaluation to measure the improvement in algorithm efficiency and analyzes the results of the performance evaluation. When spatial data queries are conducted, according to our performance evaluation, hit rate has been improved over the existing algorithms.

• Journal of Digital Contents Society
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• v.10 no.3
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• pp.395-400
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• 2009

The wide spread of the Internet service has brought in web GIS development. But, there are problems of the user access latencies, the network traffic, and the server overload in Internet Geographic Information System because spatial data are transferred in large volumes. In this paper, I propose a cache algorithm on client side to solve the above problems. The proposed algorithm demonstrates the performance improvement over known studies by utilizing unit time and spatial proximity. In addition, this paper conducts a performance evaluation to measure the improvement in algorithm efficiency and analyzes the results of the performance evaluation. When spatial data queries are conducted, according to our performance evaluation, hit rate has been improved over the existing algorithms.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.29-34
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• 2007

It is important to analyse the frequency spectrum for the measurement of modulated signal, distortion, and noise. The frequency spectrum analysis is performed by the execution of Radix-2 DIT DFT i.e. FFT algorithm. The discrete input signal converted by A/D converter from the input signal in time domain is mathematically transformed to the frequency spectrum by FFT algorithm. In this study, we design the digital spectrum analyser by the hardware based on the TMS320F2812 DSP and AD9244 converter, and by the software based on the C28x S/W modules. We can timely analyse the frequency spectrum in mobile communication system by the digital frequency analyser based on the high performance DSP and S/W modules. This real-time analysing capability is the important performance in the internet-based mobile communication server system.