• ETRI Journal
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• v.21 no.4
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• pp.52-64
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• 1999

QoS monitoring is a kind of real-time systems which allows each level of the system to track the ongoing QoS levels achieved by the lower network layers. For these systems, real-time communications between corresponding transport protocol objects is essential for their correct behavior. When two or more entities are employed to perform a certain task as in the case of communication protocols, the capability to do so is called interoperability and considered as the essential aspect of correctness of communication systems. This paper describes a formal approach on modeling and interoperability test case generation of a real-time QoS monitoring protocol. For this, we specify the behavior of flow monitoring of transport layer QoS protocol, i.e., METS protocol, which is proposed to address QoS from an end-to-end's point of view, based on QoS architecture model which includes ATM net work in lower layers. We use a real-time Input/Output finite State Machine to model the behavior of real-time flow monitoring over time. From the modeled real-time I/OFSM, we generate interoperability test cases to check the correctness of METS protocol's flow monitoring behaviors for two end systems. A new approach to efficient interoperability testing is described and the method of interoperability test cases generation is shown with the example of METS protocol's flow monitoring. The current TTCN is not appropriate for testing real-time and multimedia systems. Because test events in TTCN are for message-based system and not for stream-based systems, the real-time in TTCN can only be approximated. This paper also proposes the notation of real-time Abstract Test Suite by means of real-time extension of TTCN. This approach gives the advantages that only a few syntactical changes are necessary, and TTCN and real-time TTCN are compatible. This formal approach on interoperability testing can be applied to the real-time protocols related to IMT-2000, B-ISDN and real-time systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1261-1271
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• 2009

Emergence of new mobile communication services has generated new demand for spectrum. Because spectrum is a scarce public resource, demand for spectrum would exceed supply. As the demand for spectrum grows, the spectrum management policy becomes one of the most important issues in mobile telecommunications industry. Huge license charges for spectrum usage may obstruct the growth of mobile telecommunications industry. We analyze spectrum charges by international comparison for the case of 3G mobile telecommunication spectrum assignment. There are mainly two types of methods in spectrum assignment of 3G service, one is the auction and the other is the beauty contest. This article aims to analyze factors which influence on spectrum charges and to study the characteristic of spectrum charges of some selected countries. This study suggests the multiple regression model about spectrum charges.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.19-29
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• 2004

In this paper, the beam steering dipole phased array antenna systems for IMT-2000 base station have been designed. The designed beam steering dipole phased array antenna systems are constituted by the antenna part and the beam steering control system part. The antenna part is designed by the proposed flat dipole for the broadband characteristics, and the 8${\times}$8 dipole way antenna is constructed by the Proposed flat dipole for the directional radiation pattern. Besides the vertical Power divider is designed for the vertical power distribution. The beam steering control system part is designed the horizontal power divider for the horizontal power distribution, the 4-bit phase shifters and the driving circuit of phase shifters for the horizontal beam tilting. In order to evaluate a performance of the designed antenna systems, they were fabricated and the radiation characteristics were measured. From the measured results, we found that the horizontal beams were tilted by the each control signals, and the measured radiation characteristics showed good agreement with the design goals.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.171-176
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• 2005

This study designed and fabricated a multi-purpose planar antenna for base stations that are accessible to DCS, WiBro, and ISM. The proposed antenna was designed into an open loop form from the existing monopole structure. The capacitance of the multi-purpose antenna was increased by the coupling of open parts. This makes the use of MMIC and LTCC convenient and the antenna is smaller and has a larger gain than existing antennas. The resonance distance and bandwidth can be adjusted by changing the open gap and the height of the loop of the antenna. The bandwidth of the designed antenna satisfies DCS, IMT-2000, WiBro, Bluetooth, wireless LAN and ISM bands based on VSWR 2. The entire frequency bandwidth is $58.75\%$ of $1.575GHz\~2.985GHz(1.41GHz)$. Also, the radiation pattern of the antenna displayed co-polarization and cross-polarization characteristics at 1.6GHz, 2.3GHz and 2.8GHz.

• Information Systems Review
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• v.5 no.2
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• pp.37-51
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• 2003

Mobile business noticed as a constructive alternative of e-commerce and e-business is being diversely considered as a new form or subset of e-business. In this study, mobile business is defined as a comprehensive alternative including e-business. The framework of the superset of e-business has two axes: connectivity and mobility. In addition, various cases based on the combination of the components are provided and explained. It is the main characteristic of this study that the element of off-line "mobility" is added to "connectivity" generally used while explaining e-commerce and e-business. For place (or location) is a prerequisite for the feature of mobility, we grope for why and how Location-Based Service (LBS) will take an important role in the development of new e-business models and services. As the real and full-scale beginning of IMT-2000 service and the rapid progress and diffusion of mobile communications services including wireless LAN require an immense and innovative way of thinking about e-commerce and e-business, the framework suggested in this study is considered to go far toward satisfying the new needs in this area.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.336-349
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• 2001

Intelligent Network (IN) is an architectural framework for the rapid and uniform provision of advanced services. Therefore, Next-generation IN platform should support fast service handling, the dynamic adaptation of various services according to various requirements of users. In this paper, we design and implement the Service Control Point (SCP) that is based on the Internet environment. Especially, we consider the service flexibility, the dynamic distribution of service and propose a set of mechanisms to optimize the performance of this platform. This SCP consists of the platform kernel to control intemal operations, tbe service manager to control all of services, SLPI (Service Logic processing Program Instance) manager to manage each service, and SLPI to handle service interaction. In addition, we propose the Service Creation Environment (SCE) to create easily services on the implemented platfonn and show the example of Call Forwarding service operated on this platform.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.4
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• pp.67-75
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• 2001

3GPP proposed f8 and f9 algorithms based on the block cipher KASUMI to provide the data confidentiality and integrity over a radio access link for IMT-2000(W-CDMA). Also 3GPP proposed Milenage algorithm based on the block cipher Rijndael to provide an example set for 3GPP authentication and key generation functions. In order to analyze the security of 3GPP algorithms, we must go ahead an analysis of security of KASUMI and Rijndael. Since S-box is an important point of security of block cipher, in this paper we analyze the S-boxes of KASUMI and Rijndael and compare the S-boxes of KASUMI with the S-box of Rijndael. Although KASUMI S9-box is bad for AC and SAC, we find that AC of KASUMI FI function containing S7-box and S9-box is equal to AC of Rijndael S-box and SAC of KASUMI FI function is better than SAC of Rijndael S-box.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.67-75
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• 2003

The development of mobile phone is growing fast in the all over the world. Besides the basic voice communication, many multimedia services and global roaming service are capable in the 3rd generation mobile telecommunication. Because mobile phone has been the essential tool to communicate, the protection of privacy and the safe transmission are critical ones. In synchronous, asynchronous mode IMT2000 service, the mechanism of mutual authentication and generation of cipher key and integrity key are implemented in smart card chip called UIM, USIM. In this paper, we describe the authentication mechanism of 3GPP and 3CPP2 and its implementation results. Then, we specify a few problems which are not defined in standard.

• Journal of Gifted/Talented Education
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• v.14 no.2
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• pp.1-18
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• 2004

This study attempted to survey the present status of the eight students who, 17 years from now, had participated in a special program for 170 days preparing for early entrance to the KAIST. With six students who responded to the questionnaire previously sent, the study focused on each participant's achievement at present, his evaluation on Accelerated Education, his personal opinions on early entrance to university and Gifted Science Education. From the survey, we could find out that three participants had received a doctorate and they are currently working as researchers at research center or professors at university. The other three participants are working as researchers at research center after receiving the M. S. Academic achievements vary according to each participant, but three of them, who ranked high in research achievement, had their articles published in international journals of the SCI level even when they were between 25 and 28 of age. Two of them in particular showed outstanding engineering and developing the commercial modem for IMT 2000 for the first time in Korea. One participant entered Harvard University to major in physics and afterwards studied the law in UCLA. He is now a professor in the law department. Concerning the evaluations on Accelerated Education and early entrance system, four participants answered positively while two participants expressed negative attitudes. When asked their opinions on the Gifted Education in Korea, such problems were pointed out as too much pressure of entering the first-class universities, the tendency to avoid choosing science-related major at universities, the lack of education system that encourages creative thinking, etc. It is necessary that the accelerated education play an important role to maximize their hidden potentials. It remains to be seen in what places these six participants will find themselves and of what ideas they will come up within the next 17 years. It will be worthwhile to wait until then for another survey.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.2
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• pp.1-8
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• 2005

In this paper, n system did research about effect that interference effect with neighborhood single equipment or group equipment gets in DMB service. For this, 2.6425 GHz SDMB(Satellite Digital Multimedia Broadcasting) that a special of electric wave interference is near frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and degree of 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect that get in service analyzed comparison ud, modulation of broadcasting relay net and interference measurement equipment used Impulse and OFDM methods. Impulse method was $BER=1{\times}10^4$ that broadcasting signal receiption is possible at 1.4m point because interference effect happens from 2m point in SDMB system, and it was $BER=1^{\times}10-4$ that OFDM method receives interference effect from 0.8m point and broadcasting signal receiption is possible at 0.5m point. Also, about gap-filler center frequency, in case of space interval more than 0.01m, there was no interference effect. Therefore, for the electric wave of W system that is small output applies to system without interference effect in DMB service, confirmed that UWB system of OFDM method is less interference effect than UWB system of impulse method.