• The Journal of the Acoustical Society of Korea
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• v.27 no.6
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• pp.271-278
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• 2008

The electro-mechanical characteristics were theoretically analyzed for the wideband ultrasonic transducer made of non-uniform thickness piezoelectric vibrator. This paper proposes a combination of exponential functions which describes the thickness variation along the length of the vibrator to derive the input admittance and power transfer function of the transducer. The bandwidth and the power transfer function of the transducer were investigated while the lateral shape of the vibrator changes. The results showed there is an optimum shape for the wideband characteristics of the transducer, and the bandwidth has increased up to over 100% as the ratio of minimum value of thickness to maximum value decreases. However, the power transfer function had a downward trend as the ratio of thickness decreases. Also we confirmed that even though the value of transfer function increases as the length of the piezoelectric vibrator increases, the shape providing wideband characteristics is very limited. It means that precision processing is required to manufacturing a wideband ultrasonic transducer with high efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.80-85
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• 2011

The mount of network traffic from the Internet is increasing because of the use of Broadband Convergence Networks(BcN). Network traffic is also increasing because of the development of application, especially multimedia traffic from IPTV, VOD, and online games. This multimedia traffic not only has a huge payload but also should be considered a threat in real time. For this reason, this study examines the ways that routers distribute the bandwidth in accordance to traffic properties. To classify the property of the traffic, it is essential to analyze the application layer. However, the general network processor architecture serially processes the L2-4 and L7 layer. We propose a novel parallel network processor architecture with a global cache that processes L2-4 and L7 in parallel. To verify the proposed architecture, we simulated both of the architecture with SystemC. EEMBC and SNORT was used to measure L2-4 and L7 processing time. When multimedia traffic was entered into the network processor in the same flow, the proposed architecture showed about 85% higher performance than general architecture.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.2
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• pp.55-61
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• 2017

In radio astronomy, high-capacity HDDs are being used to save huge amounts of HDDs in order to record the observational data. For VLBI observations, observational speeds increase and huge amounts of observational data must be stored as they expand to broadband. As the HDD is frequently used, the number of failures occurred, and then it takes a lot of time to recover it. In addition, if a failed HDD is continuously used, observational data loss occurs. And it costs a lot of money to buy a new HDD. In this study, we developed the integrity verification system of the Serial ATA HDD using FirmOS. The FirmOS is an OS that has been developed to function exclusively for specific purposes on a system having a general server board and CPU. The developed system performs the process of writing and reading specific patterns of data in a physical area of the SATA HDD based on a FirmOS. In addition, we introduced a method to investigate the integrity of HDD integrity by comparing it with the stored pattern data from the HDD controller. Using the developed system, it was easy to determine whether the disk pack used in VLBI observations has error or not, and it is very useful to improve the observation efficiency. This paper introduces the detail for the design, configuration, testing, etc. of the SATA HDD integrity verification system developed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.3
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• pp.98-109
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• 2002

Bluetooth technology is a publicly available specification proposed for Radio Frequency (RF) communication for short-range :1nd point-to-multipoint voice and data transfer. It operates in the 2.4㎓ ISM(Industrial, Scientific and Medical) band and offers the potential for low-cost, broadband wireless access for various mobile and portable devices at range of about 10 meters. In this paper, we describe the structure and the test results of the bluetooth baseband module with direct memory access method we have developed. This module consists of three blocks; link controller, UART interface, and audio CODEC. This module has a bus interface for data communication between this module and main processor and a RF interface for the transmission of bit-stream between this module and RF module. The bus interface includes DMA interface. Compared with the link controller with FIFOs, The module with DMA has a wide difference in size of module and speed of data processing. The small size module supplies lorr cost and various applications. In addition, this supports a firmware upgrade capability through UART. An FPGA and an ASIC implementation of this module, designed as soft If, are tested for file and bit-stream transfers between PCs.

• The KIPS Transactions:PartC
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• v.12C no.7 s.103
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• pp.989-998
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• 2005

Information systems are today becoming larger and mostly broadband-networked. This exposes them at a higher risk of intrusions and hacking than ever before. Of the technologies developed to meet information system security needs, risk analysis is currently one of the most actively researched areas. Meanwhile, due to the extreme diversity of assets and complexity of network structure, there is a limit to the level of accuracy which can be achieved by an analysis tool in the assessment of risk run by an information system. Also, the results of a risk assessment are most oftennot up-to-date due to the changing nature of security threats. By the time an evaluation and associated set of solutions are ready, the nature and level of vulnerabilities and threats have evolved and increased, making them obsolete. Accordingly, what is needed is a risk analysis tool capable of assessing threats and propagation of damage, at the same time as security solutions are being identified. To do that, the information system must be simplified, and intrusion data must be diagrammed using a modeling technique this paper, we propose a modeling technique information systems to enable security risk analysis, using SPICE and Petri-net, and conduct simulations of risk analysis on a number of case studies.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.991-1002
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• 2004

Online game business has emerged as the most lucrative entertainment industry, with over 20 million platers. The popularity of online games can be attributed to the presence of numerous PC Bangs around the country, which have pushed online games into the mainstream culture while broadband internet services facilitated online game play. The age distribution of online game players is expanding and a variety of new games are under development to target certain age groups. While the online game market continues to expand, with many new online game publishers entering the market, relatively little is known about which factors are strategically important for successful development of online games. A conceptual framework is proposed, and a structural equation modeling, for Identifying the factors affecting the market success of online games, is developed. The concept of online game community, idea generation, systematic development strategy, flexible development process, utilizing demo-version, outsourcing, etc, are ail introduced into the model, as the independent variables affecting the success level of online games directly and indirectly. Based on data collected from questionnaire survey, the validity of the model has been tested and interesting conclusions have been developed concerning the relationships between these variables. Statistical results show that utilizing online game community and system atic development strategy is the key for successful online game development. Other interesting results concerning game development strategy are also provided. It is hoped that this result might provide the useful guidelines for developing the successful online game contents. With a better understanding of key success factors, online game developers should be able to make adjustments in their development and marketing plans, providing them with a sustainable advantage over their competition.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.773-780
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• 2005

Recently, the telecommunication network is in a transition toward the BcN (Broadband convergence Networks) that integrates the Internet, the telecommunication and the broadcasting. The BcN makes it possible to provide of 4he third-party application by using the Open API The Parlay X API is an example of the Open API and the Parlay X API is grafted in the Web Service and is abstracted from the Parlay API. So, the Parlay X API does not only have advantages of a Web Service, but also disadvantages of the Web Service. The main disadvantage of the Web Service is that it does not support the any QoS mechanism. In this paper, we propose the architecture that solves the reliability among the QoS issues for the Web Service. The proposed mechanism adopts the Asynchronous architecture for the reliable Web Service and improves the performance of the retransmission between the client and the server using the expected response time. We perform the performance evaluation through the simulation in older to compare with the existing mechanism. Consequently, we can confirm that the performance of the proposed mechanism performs better than the existing mechanism.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.1
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• pp.35-46
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• 2012

The development of wireless communication systems has resulted in the availability of several access technologies at any geographic area, such as 3G networks, wireless local area networks (WLANs) and wireless broadband networks. The development of these technologies is provided for users who have experienced mobile network environments which are slow or fast-movement environment and change distance between the AP(Access Point). This paper describes network performance issues in various environmental changes. Also, Fuzzy logic is applied to evaluate the performance in vehicle networks around users' environmental factors to focusing on the minimizing of transfer time and costs. First, WLAN and 3G networks fixed distance between AP, Second, WLAN and 3G networks random distance between APs, finally above two environmental with vehicle Ad hoc networks is analyzed. These V2I and V2V environmental condition are assumed. Results which based on Fuzzy logic suggest an optimal performance in vehicle network environments according to vehicle speed and distance between APs. Proposed algorithm shows 21% and 13% improvement of networks performance in V2I and V2V environment.