• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.44 no.10
• /
• pp.904-910
• /
• 2016

The choice of nulling antenna type to be used for a given specification of user locations usually centers on whether to use a phased array antenna(PAA) or a multiple-beam antenna(MBA) for a satellite payload. This paper considers a MBA to analysis the nulling effect in the Korean peninsula jamming circumstance. First, the nulling performance and characteristics on the region of the earth coverage are confirmed with respect to the case of 7 beams. Then, optimum results are derived and compared to what can be accomplished with a fixed set of beams(the case of 10 and 19 beams are considered) for null steering to reject interference is investigated for a MBA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.6
• /
• pp.690-697
• /
• 2010

In this paper we propose an opposite-sign phase method to implement a nulling antenna using genetic algorithm. In the opposite-sign phase method the phase value of each antenna element in the linear phased array antenna is symmetrical to the center of the array and the sign of the phases of the neighboring elements is alternating. Compared to the conventional genetic algorithm our genetic algorithm shows the capability of synthesizing nulls faster and sharper.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.11
• /
• pp.1-7
• /
• 2004

We propose multistage parallel nulling (MPN) partial parallel interference cancellation (PPIC) receiver for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-code division multiple access (CDMA) systems. Though the V-BLAST is a popular MIMO receiver, it shows error floor for multiuser downlink MIMO MC-CDMA systems. The proposed MPN-PPIC receiver does not produce error floor for multiuser case, and achieves substantial performance gains with multistage processing. For single user case, the proposed method also surpasses the V-BLAST receiver with multistage processing for MIMO MC-CDMA systems with chip level interleaving. The system performance of the proposed MPN-PPIC receiver is evaluated through computer simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.8
• /
• pp.676-683
• /
• 2016

In this paper, an adaptive nulling algorithm which can be used to form nulls in the direction of jammer or interference signals in array antennas of single port system is proposed. The proposed adaptive algorithm does not require a priori knowledge of the incoming signal direction and can be applied to the partially adaptive arrays. This algorithm is the combination of the PSO(Particle Swam Optimization) algorithm and the gradient-based perturbation adaptive algorithm, which shows stable nulling performance adaptively even on the moving jammer environment where the incident direction of the interference signal is changing with time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.9
• /
• pp.808-816
• /
• 2016

In this paper, a new technique and cost function which can be to classify jamming signal and target signal from the spectral distribution of received signal in order to minimize the main beam distortion of target signal and to form nulls in the direction of jamming signal in array antennas of single port system is proposed. The proposed cost function is applied to the adaptive algorithm which has the fast convergence and stable nulling performance through the combination of the PSO(Particle Swam Optimization) algorithm and the gradient-based perturbation algorithm, which shows stable nulling performance adaptively even under the moving jamming signal where the incident direction of the jamming signal is changing with time.

• Electronics and Telecommunications Trends
• /
• v.10 no.4 s.38
• /
• pp.57-83
• /
• 1995

이동통신과 관련된 표준은 코드리스폰과 셀룰러 이동전화에서 독립적으로 시작되어 PCS, UPT, FPLMTS의 통합된 규격으로 발전하고 있다. 본 고는 먼저 이동통신 발전동향에 대하여 기술하였고, 망구조 및 구성요소간의 통신 및 망간 통신에 필요한 시그널링, 지능망 그리고 지능망을 이용하여 가입자에게 제공되는 UPT 및 개인통신서비스에 대하여 기술하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.11
• /
• pp.9-15
• /
• 2004

We propose optimal interference rejection weight for multistage parallel nulling (MPN) partial parallel interference cancellation (PPIC) receiver previously proposed to enhance the performance of V-BLAST for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-code division multiple access (CDMA) systems. MPN-PPIC method proposed in [1] was based on the parallel interference cancellation (PIC) with fixed interference rejection weight obtained experimentally. However, the fixed weight can not be adapted to various systems efficiently, thus we proposed method for the optimal interference rejection weight based on the received signal to interference and noise ratio (SINR), and the performance of the proposed method was evaluated through computer simulation comparing with the previous method. We obtained performance gains of 2.5 dB ~ 5 dB for BER of 10$^{-3}$ .

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.2 no.3
• /
• pp.84-89
• /
• 2003

The joint method and characteristics of lubricant Impregnated MC nylon and metal are analyzed. Considering the productivity and economics, two materials are Joined with the process of turning, knurling, and induction heating. The Joint strength is determined by adhesion of the melted nylon, the size of knurl, and the interference from the difference of the diameters. The parameters affecting induction heating process are analyzed. The adhesion strength of the melted nylon is measured. Finally the joint strength is analyzed in the environments of low, room, and high temperature. The nylon/metal Joined material is expected to be widely used as the sliding machine elements with good friction and shear strength.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.11
• /
• pp.1449-1457
• /
• 1997

Since a non-nulling method of five-hole probes is valid only when the flow angle is within the calibrated angle range, it can not be used in a complex flow field. Full angle range pressure coefficient maps show that widely used nulling methods do not guarantee correct alignment of the probe with the flow direction in the unknown complex flow field. Zone decision method and features of zone map were studied by investigating the full angle range pressure coefficient maps. A reliable and efficient new nulling algorithm using zone decision by pressure ordering is proposed and verified. Since the zone decision method by pressure ordering can decide whether the flow is within the calibration angle range or not, it is useful in wide angle nonnulling methods, too.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.769-772
• /
• 2003

기존 유선 전화방식과 비교하여 적은 비용으로 다양한 서비스 제공이 가능하다라는 경제적인 관점에서만 인터넷 전화방식을 주로 바라보았으나, 최근 들어 기존 유선 전화 서비스망에서 제공되지 못했던 사용자의 편리성을 고려한 새로운 서비스 창출이라는 관점에서 많은 관심이 집중되고 있다. 인터넷 사용자들의 급격한 증가로 인하여 인터넷을 이용한 다양한 부가 서비스들이 창출되고 있으며, 프리젠스기반 인스턴트 메시징 서비스도 그중 하나이다. 이에, 기존 인터넷 전화 서비스 제공을 위한 시스널링 프로토콜인 SIP을 이용하여 프리젠스 및 인스턴트 메시징 서비스를 제공하려는 시도가 IETF SIMPLE WG을 중심으로 일어나고 있다. 본 고에서는 SIP기반 IMPP 서비스 제공을 위한 IMPP 시스템에서 클라이언트와 서버간에 버디 목록, 인가(Authorization) 정보와 같은 데이터를 주고받기 위한 시스템 프레임워크 및 XCAP을 이용한 데이터 관리 방법을 소개한다.