• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5A
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• pp.674-681
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• 2000

We proposed polymer based vertical asymmetric optical coupler. And we optimized the proposed device by coupling characteristic analysis In 1.33um wavelength, TE mode, we obtained very short coupling length(L=277.6um), high coupling efficiency(94%). The merits of proposed device are low propagation loss due to very short full device, low production cost and time, and high integrated fabrication. We will use this to fabricate optical switch, modulator and tunable WDM devices, etc.

• Journal of KIISE:Information Networking
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• v.32 no.1
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• pp.51-59
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• 2005

In this paper, we propose and implement a hybrid-type video conference system using SIP protocol proposed in IEFT. This conference system, all signaling is controled by the server, while the media communication can be managed either by UAs or by the server. as a result, the complexity of its routing and user state management is reduced and it is applicable to the mobile environment of the ad-hoc models. The implemented server is scale enough to be used in a large conference because it only takes charge of signaling part. And also we see that UAs are only suitable in the small conference where less than ten people can join.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.245-253
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• 2010

In this paper, we derive the performance analysis of the coded cooperation over a Rician fading channel. A new scheme called coded cooperation was suggested by using user cooperation and channel codes simultaneously. In previous works, it was verified that the coded cooperation schemes have better performance than other relay schemes in a Rayleigh fading channel. However, the high speed short range indoor wireless communication system has recently attracted research attention and its channel with very high carrier frequency(60GHz) can be typically modeled as a Rician fading channel. We derive analytical outage probabilities and bit error probabilities of the coded cooperation over the Rician fading channel and prove it to have full diversity order.

• Journal of Information Management
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• v.26 no.2
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• pp.111-130
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• 1995

New technologies will soon bring fundamental changes to the process of scientific communication. To understand the path that these changes may take in the future, we need to take a careful look at the past. By examining the history of scientific communication, we can see how new technologies can interact with changes in communication forms. By looking at the complex roles that journals have traditionally played, we can better understand how and when journals may incorporate these new technologies. From these models we can project that electronic journals must meet the basic needs that print journals do, that they will initially maintain many of the features of traditional print journals, that their transformation may be driven by external forces, and that they will be slow in reaching their full potential.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.161-172
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• 2000

In this paper, we introduce the development of a LOTOS-based tool, supporting formal methods, called ForTIA (A Formalism for Telecommunication and Information Systems). By using LOTOS, an ISO standard formal specification language, the user requirements and system models can be abstracted and represented formally. Therefore, the system can be validated and verified on the specifications, before implementations. ForTIA supports light-weight formal methods based on validation to be used in real industry. Key functions of ForTIA are simulation and C++ code generation. In simulation, tree based visual validation mechanism is provided and in code generation, the full C++ source code is generated to be used for system implementations.

• The Journal of Industrial Distribution & Business
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• v.9 no.4
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• pp.19-26
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• 2018

Purpose - This study measures how competitive securities broker-dealers are in the Korean financial markets. It aims to test whether the markets are perfectly competitive or monopolistic since the global financial crisis of 2008. Research design, data, and methodology - We apply the method developed by Panzar and Rosse (1987), H-statistics, which offers an index for the competitiveness as well as statistical tests. The dataset in use is retrieved mainly from the quarterly statements of the financial services companies by the Financial Statistics Information System of the Financial Supervisory Service. General information on officers and employees is utilized in addition to balance sheets and income statements of securities companies. Results - H-statistics for 2009-2015 is about 0.7 that is a robust estimate regardless of model specifications such as full trans-log, partial trans-log, and Cobb-Douglas regression equations. H-statistics for each year is also computed in similar ways in that it varies between 0.3 and 0.9. Conclusions - Since the global financial crisis, H-statistics concludes that securities broker-dealer markets in Korea is neither perfectly competitive nor monopolistic. It evidences that the markets are rather monopolistically competitive. The trend in annual H-statistics leads to the same conclusion but the result is not such stable that overall H-statistics implies.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.7
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• pp.369-378
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• 2020

The paper aims to identify the determinants that influence entrepreneurial intention among National Economics University graduates. For the sample size, we conducted a questionnaire survey of 250 full-time third-year undergraduates at the National Economics University, with convenience sampling technique. Of those 250 undergraduates, 150 were Business Administration students and 100 Economy Management students. After eliminating invalid responses due to lack of information or low quality information, 215 responses were used (93.07% of respondents) for data analysis. The results show that the factor "Perceived desirability" has the strongest impact on the intention to start a business. It is followed by the factor "Perceived feasibility" in which the "ability to search and plan for start-up" has a stronger influence on undergraduates' entrepreneurial intention than the "leadership and ability to overcome adversity". The hypothesis of a positive relationship between undergraduates' propensity to act and their intention to start a business is also supported in this study. Based on the results, we suggest some recommendations for the university and State management agencies to nurture and develop entrepreneurial intention of undergraduates, forming the young generation of potential entrepreneurs to contribute to the development of emerging countries such as Vietnam, the case study.

• Journal of the Society of Disaster Information
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• v.10 no.3
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• pp.388-395
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• 2014

In this paper, usability and use force on the structure and does not have a big impact on the development of existing materials developed using materials to their full impact/blast resistant Complex configuration on the panel that can be implemented. Each material of the characteristics so that they can exert in layers of layer formed panels in layers. Structure of the general structure is to keep strength and endurance, maintenance and minimize the damage can be utilized for knee brace to do basic research, for creating the panel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.828-835
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• 2004

An adaptive hexagon based search(AHBS) algorithm is proposed in this paper to perform block motion estimation in video coding. The AHBS evaluates the value of a given objective function starting from a diamond-shaped checking block and then continues its process using two hexagon-shaped checking blocks until the minimum value is found at the center of checking blocks. Also, the determination of which checking block is used depends on the position of minimum value occurred in previous searching step. The AHBS is compared with other fast searching algorithms including full search(FS). Experimental results show that the proposed algorithm provides competitive performance with slightly reduced computational complexity.

• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.85-97
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• 2004

Distributed Denial-of-Service(DDoS) attack prevent users from accessing services on the target network by spoofing its origin source address with a large volume of traffic. The objective of IP Traceback is to determine the real attack sources, as well as the full path taken by the attack packets. Existing IP Traceback methods can be categorized as proactive or reactive tracing. Proactive tracing(such as packet marking and messaging) prepares information for tracing when packets are in transit. Reactive tracing starts tracing after an attack is detected. In this paper, we propose a "advanced ICMP Traceback" mechanism. which is based on the modified push back system. Proposed mechanism can detect and control DDoS traffic on router and can generate ICMP Traceback message for reconstructing origin attack source.ck source.