• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.312-318
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• 2006

WRC-2000 allowed HAPS to provide IMT-2000 service in the bands 1885-1980 MHz, 2010-2025 MHz and 2110-2170 MHz which have been utilized by the conventional terrestrial IMT-2000 service. In this paper, we analyze the interference effects from HAPS into terrestrial IMT-2000 system in adjacent band. To do this, in this paper, we have analyzed the interference and the sharing criteria between HAPS and the conventional terrestrial/satellite mobile system by considering the service and system requirements, the specification of system and developing the interference scenarios and the analysis algorithms.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1216-1224
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• 2003

In this paper Dual Band Log-Periodic Dipole Antenna(DLPDA), which can be used at the Cellular/IMT-2000 band, is proposed. The proposed antenna is composed of 2 of Log-Periodic Dipole Antenna(LPDA) and parasitic elements. To investigate the reliability of the proposed antenna, DLPDA is designed at the cellular/IMT-2000 band and analyzed by using the method of moment, Numerical results are compared with measured results. It is shown that although the antenna length is 70 cm, its radiation characteristics satisfied the design goals of gain, VSWR and beamwidth at the Cellular/IMT-2000 band. From these results, the proposed DLPDA is confirmed as the dual band antenna which can be used at the cellular/IMT-2000 band.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.121-131
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• 2019

The ionospheric mid-latitude trough (IMT) is the electron density depletion phenomenon in the F region during nighttime. It has been suggested that the IMT is the result of complex plasma processes coupled to the magnetosphere. In order to statistically investigate the characteristics of the IMT, we analyze topside sounding data from Alouette and ISIS satellites in 1960s and 1970s. The IMT position is almost constant for seasons and solar activities whereas the IMT depth ratio and the IMT feature are stronger and clearer in the winter hemisphere under solar minimum condition. We also calculated transition heights at which the densities of oxygen ions and hydrogen/helium ions are equal. Transition heights are generally higher in daytime and lower in nighttime, but the opposite aspects are seen in the IMT region. Utilizing the Incoherent Scatter Radar (ISR) electron temperature measurements, we find that the electron temperature in the IMT region is enhanced at night during winter. The increase of electron temperature may cause fast transport of the ionospheric plasma to the magnetosphere via ambipolar diffusion, resulting in the IMT depletion. This mechanism of the IMT may work in addition to the simply prolonged recombination of ions proposed by the traditional stagnation model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.161-167
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• 2008

This paper describes the overview of spectrum requirement estimation recommended in ITU-R Rec. M.1390 and [IMT.METH] and its difference for the IMT mobile service, and a (IMT.METH) methodology is applied to the spectrum estimation of the recent IMT service. The traffic model and traffic calculation algorithm is briefly described for the carried traffic which is determined in terms of the offered traffic, system rapacity, and the criteria of quality of service. And the spectrum requirement demand which is required from year 2010 to year 2015 is calculated as an example for the IMT service which is recently operated and deployed in the current Korean market after obtaining the reasonable market data and the ITU market prediction data.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.587-595
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• 2010

Spectrum sharing between wireless systems becomes a critical issue clue to emerging new technologies and spectrum shortage. Recently, IMT system has been allocated in the same frequency C band (3400-4200MHz) along with FSS services on co-primary basis which means that harmful. interference probability may be inspired. In this paper, to estimate the spectrum sharing between IMT and FSS systems, I propose the minimum separation distances as a sharing criterion of I/N=-10dB using the interference to noise ratio(I/N) received at the reference FSS earth station from IMT multiple base station. Especially, same results imply that I/N values can be greatly reduced with MMO SDMA interference mitigation technique of IMT base station so that FSS and IMT systems can co-exist in the sam e frequency with appropriate separation distance.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.453-456
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• 2000

This paper describes IMT-2000 Testbed System which consists of ATM based IMT-2000 exchange(A-lMX), RNC simulator, HLR simulator, SCP simulator, B-ISDN subscriber simulator and MS simulator. Simulators were developed to verify the mobile functions and basic services of IMT-2000 like Videophone, VoD(Video on Demand), and Internet access. UPT(Universal Personal Telecommunication) service could be adapted well to this testbed system. Until the entire network elements are developed fully, this testbed system can be used to prove new services in IMT-2000 network.

• Electronics and Telecommunications Trends
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• v.15 no.6 s.66
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• pp.35-44
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• 2000

우리 나라에서는 IMT-2000 상용서비스를 2002년에 제공할 것을 추진하고 있다. 따라서 국내 이동통신 장비업체들은 IMT-2000 시스템 개발에 더욱 박차를 가하고 있다. 국내에 구축되는 IMT-2000 시스템에는 비동기 시스템이 포함될 것이며, IMT-2000 서비스에서 제공하고자 하는 멀티미디어 통신이 범 세계적으로 가능하기 위해선 모든 관련 장비가 정확히 구현되어야 한다. 그래서 본 고에서는 우선, 비동기 방식인 WCDMA 단말기가 정확히 구현되었는지를 확인하기 위해서 WCDMA 단말기의 기능 및 성능평가를 위한 시험 요구사항에 대하여 분석하였다.

• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.34-40
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• 2021

For developing a switching device of a new concept that cannot be implemented with a semiconductor device, we introduce the Mott insulator-metal transition (IMT) phenomenon occurring out of the semiconductor regime, such as the temperature-driven IMT, the electric-field or voltage-driven IMT, the negative differential resistance (NDR)-IMT switching generated at constant current, and the NDR-based IMT-oscillation. Moreover, the possibilities of new concept IMT switching devices are briefly explained.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.279-281
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• 1998

기존 이동통신 시스템은 단말 및 개인 이동성의 결여, 저조한 데이터 전송율, 그리고 서비스 도입 및 호환성의 어려움이 존재한다. 이를 해소하기 위해 국제적으로 차세대 이동통신 시스템으로 IMT-2000에 대한 연구와 개발이 이루어지고 있다. 또한 IMT-2000은 기본적으로 지능망에 근간한 구조를 지향하며, 다양한 서비스들의 실현 및 신속한 도입을 위하여 지능망이 IMT-2000의 기능 모델 표준으로 채택되고 있으며. 이를 기반으로 다양한 서비스가 개발되고 있다. 한편 IN CS-2의 목표서비스(target service) 의 하나로서 가상 사설망 서비스는 기존 사설망의 독립적인 망 운영을 유지하면서, 공중망의 자원을 이용하여 기존 사설망의 과다한 초기 투자 비용을 해소시키는 장점을 제공한다. 본 논문은 IMT-2000의 서비스 제어를 위해 IMT-2000의 망 구종에 도입된 지능망 모델을 분석하고 IMT-2000상에서 특히 기존 고정/이동 통신망과 달리 기본적으로 제공되는 개인 이동성을 고려하여 지능망의 서비스 제어 모델에 따라 가상 사설망 서비스를 설계한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1371-1374
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• 2001

핸드오프는 이동국이 통화 중에 이동하더라도 새로운 통화 채널을 확보하여 진행중인 호를 새로운 채널로 전환하는 과정이다. 본 논문은 IMT-2000 망에서 MSC 간 핸드오프 과정의 설계를 목적으로 한다. 이와 관련하여 IMT-2000 망 구조를 기술하고, IMT-2000 MSC 간 핸드오프 처리 방안으로 B-ISUP 메시지를 이용한 방안과 IS-41의 MAP을 이용한 방안을 비교 분석하였다. 또한, IS-41 MAP 기반의 MSC 간 핸드오프 호 처리 절차에 대해 기술하고, 핸드오프 기반의 IMT-2000 교환기 소프트웨어 블록 구조 및 기능을 설계하였다. 그리고, IMT-2000MSC간의 핸드오프 경로 구성 방안을 제시하고, IS-634와 IS-41 MAP규정을 만족하는 IMT-2000망에서의 MSC간 핸드오프를 위한 교환기 내부 소프트웨어 블록간의 호 흐름을 설계하였다.