• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.2
• /
• pp.17-23
• /
• 2016

It is essential to develop an estimation and cancellation algorithm for feedback signals in designing the interference cancellation systems (ICS) as a solution to extending the coverage of the TDD LTE networks. Unlike the radio access of FDD LTE networks, TDD networks utilize the same frequency band in downlink and uplink for radio access. For this reason, downlink and uplink are repeated in time and thus the estimation of the feedback signals in uplink and downlink, respectively, is periodically paused to cause performance degradation. In this study, the reciprocity of downlink and uplink is examined through experiments and exploiting the same frequency band in uplink and downlink, an efficient channel estimation and elimination algorithm is proposed since the algorithm utilizes the same structure for both downlink and uplink.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.8
• /
• pp.1110-1116
• /
• 2021

In this paper, we propose a conformal Ku-band data link antenna to ensure low RCS of stealth UAV. As a phased array antenna with electrical beam steering function, a transmitter and a receiver were designed and manufactured for FDD communication, respectively. Each antenna is designed as a 12*12 planar array antenna and has a function to form a uni-directional pattern and a bi-directional pattern through phase control of unit elements. The beam steering range is designed to be able to steer up to 60 degrees in theta direction and 360 degrees in the phi direction. As a result of manufacturing and measurement, the conformal type radome has low transmission loss and meets the required specifications including system performance. The feasibility of mounting the stealth UAV has been confirmed, and future research directions such as interworking of baseband devices and conversion to digital beam steering function are suggested.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.8 no.2
• /
• pp.646-663
• /
• 2014

Scrum is one of the most popular and efficient agile development methods. However, like other agile methods such as Extreme Programming (XP), Feature Driven Development (FDD), and the Dynamic Systems Development Method (DSDM), Scrum has been criticized because of lack of support to develop secure software. Thus, in 2011, we published research proposing the idea of a security backlog (SB). This paper represents the continuation of our previous research, with a focus on the evaluation in industry-based case study. Our findings highlight an improved agility in Scrum after the integration of SB. Furthermore, secure software can be developed quickly, even in situations involving requirement changes of software. Based on our experimental findings, we noticed that, when integrating SB, it is quite feasible to develop secure software using an agile Scrum model.

• Proceedings of the IEEK Conference
• /
• 2000.11a
• /
• pp.117-120
• /
• 2000

This paper discusses solutions for forward link power allocation based on 3GPP(FDD) standardization reports and which meet the required Eb/No of forward link channels. In addition, the forward link user capacity in a mixed service environment. Cell coverage is induced from the user capacity solutions using the urban propagation model. In an urban macrocell environment, the forward link user capacity turns out to be roughly 29 and 3, respectively, for voice and data service (144 kbps) at a distance of 1 km, and in an urban microcell environment, the user capacity turns out to be Toughly 14, 4, and 2, respectively, for voice and two data services (144 kbps, 384 kbps) when the cell radius is 0.2 km.

• Journal of IKEEE
• /
• v.15 no.1
• /
• pp.70-75
• /
• 2011

Longitudinal recording has been the cornerstone of all two generations of magnetic recording systems, FDD and HDD. In recent, perpendicular recording has received much attention as promising technology for future high-density recording system Research into signal processing techniques is paramount for the issued storage system and is indispensable like longitudinal recording systems. This paper focuses on the performance evaluation of the various detectors under perpendicular recording system. Parameters for improving the their performance are examined for some detectors. Detectors considered in this work are the partial response maximum likelihood (PRML), noise-predictive maximum likelihood (NPML), fixed delay tree search with decision feedback (FDTS/DF), dual decision feedback equalizer (DDFE) and multilevel decision feedback equalizer (MDFE). Their performances are analyzed in terms of mean squared error (MSE) and noise power spectra, and similarity between recording channel and partial response (PR) channel.

• Journal of Information Processing Systems
• /
• v.9 no.1
• /
• pp.69-88
• /
• 2013

Agile methods are highly attractive for small projects, but no agile method works well as a standalone system. Therefore, some adaption or customization is always required. In this paper, the Agile Framework for Small Projects (AFSP) was applied to four industry cases. The AFSP provides a structured way for software organizations to adopt agile practices and evaluate the results. The framework includes an extended Scrum process and agile practices, which are based on agility and critical success factors in agile software projects that are selected from Scrum, XP, FDD, DSDM and Crystal Clear. AFSP also helps software managers and developers effectively use agile engineering techniques throughout the software development lifecycle. The case study projects were evaluated on the basis of risk-based agility factors, the agility of the adopted practices, agile adoption levels, and the degree of the agile project success. The analysis of the results showed that the framework used in the aforementioned cases was effective.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.3
• /
• pp.459-464
• /
• 2001

We propose a transmit beamforming algerian for array antenna in FDD (Frequency Division Duplex) environments. The proposed method estimates the directions and spectra of the users, and constructs the spatial covariance matrix of the interferences at the downlink frequency. The weights are computed by that covariance matrix and desired user's direction vector Simulations are performed under Rayleigh fading environments. The proposed method don't need the data feedback, has the enhanced performance in BER (Bit Error Rate).

• Journal of IKEEE
• /
• v.6 no.1 s.10
• /
• pp.102-110
• /
• 2002

An effective scheme to detect and diagnose multiple failures in a dynamic system is described for the case where the measurement noise is correlated sequentially in time. It is based on the modified interacting multiple model (MIMM) estimation algorithm in which a generalized decorrelation process is developed by employing the autoregressive (AR) model for the colored noise and applying measurement difference method.

• The Magazine of the IEIE
• /
• v.20 no.2
• /
• pp.127-139
• /
• 1993

1980년대초부터 미국표준협회(ANSI)의 X3T9.5위원회에서 표준화가 진행되어 온 FDDI는 100 Mbps급의 고속통신망으로서 현재 다양한 컴퓨터 사업자, 제조업자들의 관심하에 실용화되고 있다. 그러나 FDDI는 구조 및 전송속도의 한계로 제한된 서비스만을 제공하기 때문에 멀티미디어, HDTV등 다양한 서비스 요구를 만족시키기 위한 새로운 통신망 구조를 필요로 하게 되었다. 이에 X3T9.5 위원회는 최근, FDDI follow-on LAN(FFOL)에 관한 표준화를 진행하고 있어 관심을 끌고 있다. 본고에서는 FFOL의 구조 및 요구사항을 기술하며, 현재까지 FFOL을 위해 제안된 대표적인 매체접근제어 (MAC)프로토콜들을 기술하고 비교 분석한다.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.10 no.2
• /
• pp.32-37
• /
• 1990

A computer controlled 5 axis ultrasonic testing system is developed in order to detect flaws in special parts with complex shape. The various kinds of ultrasonic test can be performed automatically using computer program which was developed by DHI(Daewoo Heavy Industries Ltd.). By use of this computer program, the detector location can be programed and the amplitude signal of echo can be processed digitally. The test results can be plotted graphically on a high resolution display monitor in real time base. The test data can be also saved in magnetic memory devices(HDD or FDD) as well as in the form of hard copy through color printer. The computer software contains c- scan, c+a scan processing programs as well as statistical analysis for test data.