• TTA Journal
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• s.100
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• pp.51-57
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• 2005

차세대 이동통신 표준화는 크게 네가지 분야에서 진행되고 있다. 3GPP, 3GPP2에서의 3G Evolution, IEEE 802.16에서의 Broadband Wireless Access, OMA에서의 응용서비스의 표준화, 그리고 ITU-R에서의 Spectrum 및 Beyond 3G 비전 연구 등이다. 본 고에서는 현 시점에서 각 기구에서 진행되고 있는 표준활동의 개요를 간단히 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9A
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• pp.656-663
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• 2009

In 3GPP LTE system downlink, PSS (primary synchronization signal) and SSS (secondary synchronization signal) sequences are used for initial cell search and synchronization. UE (user equipment) detects slot timing, frequency offset, and cell ID by using PSS. After that it should detect frame timing, cell group ID, and CP length by using SSS. But in 3GPP LTE, there are two kinds of CP length, so we should operate FFT twice. In this paper, to minimize SSS detection complexity in cell searcher, we propose a CP length pre-decision algorithm that reduces the arithmetical complexity by half at most, with negligible performance degradation.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.570-577
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• 2011

In this paper, Policy-based QoS in 3GPP service network management techniques are not applied to the DiffServ technology is applied to the first interpretation. The next PBNM and DiffServ associated technologies by applying QoS performance improvement is verified. In this case that PBNM and DiffServ technology is applied, the amount of voice traffic reduced about 1 msec while best-effort traffic occurs 75 percent of the output link capacity. Also, video traffic which is the same as data traffic showed a decreased $0\sim10^{-4}$ packet loss rate than the case that DiffServ technology is applied. We apply the appropriate policy PBNM and DiffServ QoS mechanisms of the existing set of policies is not affected, just by using the appropriate 3GPP Service QoS level to suit the network operation, management can do that was found. This analytical method based on the University of California at Berkeley through NS-2 DiffServ technology into existing systems and next-generation networks mandated PBNM and DiffServ technology is applied to performance evaluation for the case.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.201-211
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• 2006

The standardization of third Generation Partnership Project(3GPP) has been performed in of order to support interactive multimedia services under mobile environments. In this 3GPP, transmit diversity solutions are applied to increase the available diversity effectively using 2 or more antennas. In this paper, we analyzer the performances on STTD(Space Time Transmit Diversity) technique and its modified techniques such as STTD-OTD, CL-STTD, and 4TX-STTD out of open loop transmit diversities that the standardization of 3GPP has released. We also propose the open loop transmitter and receiver diversities to add the receiver diversity. We analyze and discuss the performance of the proposed techniques and using the Matlab simulation under the flat fading channel environment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.4
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• pp.251-267
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• 2021

Remotely sensed vegetation indices (VIs) are empirically related with gross primary productivity (GPP) in various spatio-temporal scales. The uncertainties in GPP-VI relationship increase with temporal resolution. Uncertainty also exists in the eddy covariance (EC)-based estimation of GPP, arising from the partitioning of the measured net ecosystem CO2 exchange (NEE) into GPP and ecosystem respiration (RE). For two forests and two agricultural sites, we correlated the EC-derived GPP in various time scales with three different near-surface remotely sensed VIs: (1) normalized difference vegetation index (NDVI), (2) enhanced vegetation index (EVI), and (3) near infrared reflectance from vegetation (NIRv) along with NIRvP (i.e., NIRv multiplied by photosynthetically active radiation, PAR). Among the compared VIs, NIRvP showed highest correlation with half-hourly and monthly GPP at all sites. The NIRvP was used to test the reliability of GPP derived by two different NEE partitioning methods: (1) original KoFlux methods (GPP_Ori) and (2) machine-learning based method (GPP_ANN). GPP_ANN showed higher correlation with NIRvP at half-hourly time scale, but there was no difference at daily time scale. The NIRvP-GPP correlation was lower under clear sky conditions due to co-limitation of GPP by other environmental conditions such as air temperature, vapor pressure deficit and soil moisture. However, under cloudy conditions when photosynthesis is mainly limited by radiation, the use of NIRvP was more promising to test the credibility of NEE partitioning methods. Despite the necessity of further analyses, the results suggest that NIRvP can be used as the proxy of GPP at high temporal-scale. However, for the VIs-based GPP estimation with high temporal resolution to be meaningful, complex systems-based analysis methods (related to systems thinking and self-organization that goes beyond the empirical VIs-GPP relationship) should be developed.

• Review of KIISC
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• v.12 no.3
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• pp.57-66
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• 2002

3GPP(3rd Generation Partnership Project) NDS(Network Domain Security)에 관한 표준화 제정은 특성상 IETF와의 협의를 통하여 최근에 비교적 활발히 이루어지고 있다. 차세대 이동통신의 등장과 인터넷의 발달로 인하여 여러 가지 형태의 네트워크가 존재하게 되고 또한 다양한 프로토콜과 메커니즘이 사용됨에 따라, 무선 구간에서의 안전한 액세스 외에도 유선구간에서의 정보보호 역시 중요한 문제로 대두되고 있다. 본 고에서는 3GPP 네트워크 도메인에서의 정보보호에 관하여 최신 릴리즈 5 버전을 중심으로 stage 2 수준으로 분석을 하였다.

• Review of KIISC
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• v.11 no.6
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• pp.63-73
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• 2001

3세대 방식인 IMT-2000 (International Mobile Telecommunication-2000)시스템은 GSM이나 IS-95 CDMA 시스템과 같은 2세대 이동통신 시스템과 비교하여 고속의 멀티미디어 서비스 제공 및 글로벌 로밍을 특징으로 한다. W-CDMA 방식 IMT-2000에 대한 인증 메커니즘은 3GPP TSG SA WG3에 의해서 개발되었다. 본 논문에서는 3GPP에서의 AKA(Authentication & Key Agreement)를 분석하고 이를 통해 안전성 분석 및 취약성을 분석한다. 본 논문에서 제기하는 안전성 분석 및 취약성 분석은 앞으로의 더 좋은 서비스를 제공할 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.639-642
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• 2001

차세대 이동통신망은 "ALL-IP Network" 이라고 불리는 차세대 이동 통신망을 위한 새로운 전송기술과 새로운 망으로 기존 망이 진화하게 될 것이다. 네트웍 계층에서 볼 때 기본적으로 이동단말기에서 IP 패킷을 생성하고 무선/유선 통신망을 통과할 때 이 IP 패킷이 그대로 유지되어 End-to-end 로 전달되는 것을 그 목표로 하고 있다. 본 논문에서는 두 상이한 이동 패킷 통신 시스템간의 Seamless한 통신을 위한 핸드오프를 Mobile IPv6 [4]관점에서 접근할 것이다. (Voice에 대한 고려는 생략하였다.)

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.245-251
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• 2016

Despite the exponential throughput improvement in mobile communications systems, their ability to satisfy requirements of state-of-the-art and future applications of advanced metering infrastructure (AMI) is still under investigation. Challenges are mainly due to the inadequacy of third generation partnership project (3GPP) networks to support large amounts of devices simultaneously, while the number of AMI end-devices and the frequency of their data transmission increase with new AMI-based applications. In this introductory survey, innovative and future AMI applications and their communication requirements are first reviewed. Then, we identify challenges of 3GPP long term evolution (LTE) in enabling future AMI applications. More importantly, the latest improvements to LTE-A standard release 12 and 13 are reviewed and analyzed with regards to their potential to improve the quality of LTE-enabled AMI. It is found that 3GPP enhancements on machine type communications (MTC) standards will significantly enhance AMI communications. Beyond MTC specifications, non-MTC-specific enhancements such as carrier aggregation and multi-connectivity for user equipment will also contribute greatly to improving reliability and availability of AMI devices. The paper's focus is towards improved backhaul support for innovative and future AMI applications, beyond traditional automatic meter reading.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.592-598
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• 2001

IMT-2000에서는 이미 터보코드가 채널코딩 기법으로 제안되어 있으며 특별히 3GPP 규격에서는 제한길이 4인 1/3 터보코드가 채택되어 있다. 기존의 논문에서는 일반적인 터보 코드의 성능에 대한 분석이 많이 제시되어 왔으나, 3GPP 규격의 터보 복호를 위한 SOVA 복호기의 성능 파라미터 추출과 그에 따른 성능 분석 수행되지 않았다. 본 연구에서는 효율적인 구조의 3GPP SOVA 복호기를 설계하기 위해서 외부정보의 스케일링과 신뢰도 갱신길이 라는 두 가지 파라미터에 따른 SOVA 복호기의 성능을 분석하고 최적의 파라미터 값을 제시하고자 한다. 이 파라미터의 최적화를 위하여 C++를 이용한 모의실험 결과, 3GPP 규격의 (13,15) 1/3 코드에서 스케일링 값은 1/2로 신뢰도 갱신길이는 10으로 최적화 되었다.