• Information and Communications Magazine
• /
• v.26 no.2
• /
• pp.23-30
• /
• 2009

3GPP(3rd Generation Partnership Project)는 3세대 이동통신인 UMTS(Universal Mobile Telecommunication System)의 초기 표준화 이후 HSPA(High Speed Packet Access), MBMS(Multimedia Broadcast/Multicast Service) 등의 기술 개발로 UMTS 시스템을 지속적으로 발전시켜 왔다. 그리고, 최근 새로운 무선 접속 기술에 기반한 LTE(Long Term Evolution)시스템에 대한 표준화를 거의 완료하고 ITU-R(International Telecommunications Union-Radio)의 IMT-Advanced 요구사항을 만족하는 LTE-Advanced 시스템에 대한 연구를 진행하고 있다. 한편 최근 다양한 무선 접속 기술간 핸드오버 기술이 중요한 이슈로 부각됨에 따라 LTE-Advanced에서도 이를 수용하기 위한 기술이 요구된다. 본 고에서는 3GPP에서 추진하고 있는 LTE-Advanced기술의 표준화 동향과 향후 이에 적용 가능한 다양한 무선 접속 기술간의 핸드오버 지원 기술을 살펴봄으로써 LTE-Advanced에서의 끊김없는 이동성(seamless mobility) 제공을 위한 근간을 제시하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.5
• /
• pp.8-15
• /
• 2011

LTE-Advanced aims at peak data rates of 1Gbits/s for the downlink and 500 Mbits/s for the uplink, which can be accomplished only by using wide spectrum allocation of 100MHz as well as advanced multiple input multiple output antenna techniques to the uplink. This paper analyzes the uplink precoding techniques which include LTE codebook of downlink, singular value decomposition codebook, and equal gain transmission codebook over LTE defined single carrier frequency division multiplexing systems. Finally considering nonlinear transmit power amplifier model, it is shown that link-level performance of EGT is superior to those of any other precoding schemes.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.17 no.1
• /
• pp.15-23
• /
• 2021

The 4th industrial revolution technology has brought many changes not only in human life but also in the industrial field. ICT such as 5G and artificial intelligence and convergence/complex systems such as drones and robots are convenient for humans, and automation of all processes in the industrial field. However, these advanced information and communication technologies also have adverse functions. As advanced ICT was incorporated into military and terrorist weapon systems, more powerful and highly destructive weapon systems began to be developed. In particular, by applying advanced ICT to the production and use of terrorist tools, the terrorist method became more sophisticated and caused more damage. In this paper, we derive advanced ICT that can be abused according to the terror patterns in the 4th industrial revolution era, and present a method that is applied from preparation to execution of terrorism. The abuse of advanced ICT makes terrorism more stealthy and subtle, and increases its destructive power.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2005.05a
• /
• pp.1305-1306
• /
• 2005

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.11
• /
• pp.2261-2270
• /
• 2015

GIS(Geographic Information System) based Positioning technique uses geographic information to predict which satellites are visible or invisible. GPS positioning has poor positioning accuracy in dense urban area where tall buildings block the satellite signals. In this paper, we proposed GIS based Advanced Positioning technique of Mobile GPS to resolve this problem. Particularly, this technique improves positioning accuracy in dense urban area. It is consist of ephemeris and GIS server. We will inversely estimate pseudorange by using NMEA-0183 output data of mobile GPS. After that, we can find more accurate position by using ephemeris and GIS information.

• Journal of the Korean Ceramic Society
• /
• v.43 no.1 s.284
• /
• pp.42-47
• /
• 2006

In this paper, we prepared high-quality ZnO thin films for application of FBAR (Film Bulk Acoustic Resonator) by using pulse DC magnetron sputtering. To prevent the formation of low dielectric layers between metal and piezoelectric layer, Ru film of 30 nm thickness was used as a buffer layer. In addition we investigated the influence of annealing condition with various temperatures. As the annealing temperature increased, the crystalline orientation with the preference of (002) c-axis and resistance properties improved. The single resonator which was fabricated at $500^{\circ}C$ exhibited the resonance frequency and the return loss 0.99 GHz and 15 dB, respectively. This work demonstrates potential feasibility for the use of thin film Ru buffer layers and the optimization of annealing condition.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.10
• /
• pp.4835-4855
• /
• 2018

In this paper, we study the sparse signal recovery that uses information of both support and amplitude of the sparse signal. A convergent iterative algorithm for sparse signal recovery is developed using Majorization-Minimization-based Non-convex Optimization (MM-NcO). Furthermore, it is shown that, typically, the sparse signals that are recovered using the proposed iterative algorithm are not globally optimal and the performance of the iterative algorithm depends on the initial point. Therefore, a modified MM-NcO-based iterative algorithm is developed that uses prior information of both support and amplitude of the sparse signal to enhance recovery performance. Finally, the modified MM-NcO-based iterative algorithm is used to estimate the time-varying sparse wireless channels with temporal correlation. The numerical results show that the new algorithm performs better than related algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.10a
• /
• pp.408-411
• /
• 2017

This paper deals with how to operate sensor data in smart livestock barn environment through EPCIS event schema design based on GS1 standard. We defines the types of sensors used in the smart livestock barn environment, describes the information using the GS1 standard identifier, standard event / master data structure, and standard interface for operating the sensor information, and stores / shares various sensor information of smart livestock barn defined in the schema structure.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.5
• /
• pp.2674-2697
• /
• 2019

Identity authentication is a crucial line of defense for network security, and passwords are still the mainstream of identity authentication. So far trawling password attacking has been extensively studied, but the research related with personal information is always sporadic. Probabilistic context-free grammar (PCFG) and Markov chain-based models perform greatly well in trawling guessing. In this paper we propose a systematic targeted attacking model based on structure partition and string reorganization by migrating the above two models to targeted attacking, denoted as TG-SPSR. In structure partition phase, besides dividing passwords to basic structure similar to PCFG, we additionally define a trajectory-based keyboard pattern in the basic grammar and introduce index bits to accurately characterize the position of special characters. Moreover, we also construct a BiLSTM recurrent neural network classifier to characterize the behavior of password reuse and modification after defining nine kinds of modification rules. Extensive experimental results indicate that in online attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 275%, and respectively outperforms its foremost counterparts, Personal-PCFG, TarGuess-I, by about 70% and 19%; In offline attacking, TG-SPSR outperforms traditional trawling attacking algorithms by average about 90%, outperforms Personal-PCFG and TarGuess-I by 85% and 30%, respectively.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.26-28
• /
• 2003