• Current Optics and Photonics
• /
• v.7 no.4
• /
• pp.387-397
• /
• 2023

Tooth surface shape error is an important parameter in gear accuracy evaluation. When tooth surface shape error is measured by laser interferometry, the gear interferogram is highly distorted and the gray level distribution is not uniform. Therefore, it is important for gear interferometry to extract the foreground region from the gear interference fringe image directly and accurately. This paper presents an approach for foreground extraction in gear interference images by leveraging the sinusoidal variation characteristics shown by the interference fringes. A gray level mask with an adaptive threshold is established to capture the relevant features, while a local variance evaluation function is employed to analyze the fluctuation state of the interference image and derive a repair mask. By combining these masks, the foreground region is directly extracted. Comparative evaluations using qualitative and quantitative assessment methods are performed to compare the proposed algorithm with both reference results and traditional approaches. The experimental findings reveal a remarkable degree of matching between the algorithm and the reference results. As a result, this method shows great potential for widespread application in the foreground extraction of gear interference images.

• Journal of Information Processing Systems
• /
• v.10 no.3
• /
• pp.384-394
• /
• 2014

The femtocell overlaid cellular network (FOCN) has been used to enhance the capacity of existing cellular systems. To obtain the desired system performance, both cross-tier interference and co-tier interference in an FOCN need to be managed. This paper proposes an interference management scheme that adaptively constructs a femtocell cluster, which is a group of femtocell base stations that share the same frequency band. The performance evaluation shows that the proposed scheme can enhance the performance of the macrocell-tier and maintain a greater signal to interference-plus-noise ratio than the outage level can for about 99% of femtocell users.

• Proceedings of the IEEK Conference
• /
• 2000.07a
• /
• pp.121-124
• /
• 2000

In this paper, we evaluate the interference statistics between the competiting wideband CDMA systems, and optimize the frequency coordination between Wideband-CDMA systems by the Monte-Carlo methodology. We develop the simulator to analyze the radio interference between CDMA systems. It can calculate or estimate the probability of interference from adjacent frequency band, which is also power controlled. We simulate the interference effects between two Wideband CDMA systems. We present the required carrier distance and zone for two operators to meet the required coverage efficiency and outage probability of Signal to interference plus noise ration (SINR).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.9
• /
• pp.791-801
• /
• 2012

Currently, SEAMCAT has been widely used as a tool to evaluate the effects of interference among a variety of wireless communication systems. This supports various channel propagation models, all of which are based on some statistical models for the channel propagation and do not exploit any specific terrain characteristics. Thus it is not appropriate for assessing the effects of interference between wireless systems, given some specific terrain features. In order to overcome this limit in its use, it is necessary to extend the capability of SEAMCAT to support a channel propagation model which takes into account terrain informations. The ITU-R P.526 is a familiar channel propagation model which calculates the path loss considering the terrain features. In this paper, we present an enhanced version of SEAMCAT which supports the ITU-R P.526 and provide a few examples of interference evaluation using it.

• Journal of the Korean Society for Railway
• /
• v.2 no.2
• /
• pp.13-20
• /
• 1999

The vibration signals of driving parts of electric train are distorted its signal patterns due to the impact components, which occurs when wheel passes rail joints. An elimination method of the impact components is investigated using adaptive signal processing technique in this study The result shows that adaptive interference canceling method seems to be more effective than line enhancement technique. The application of adaptive interference canceling method to the signal measured at bogie shows that the extractions of the signals of driving parts of traction motor, reduction gear, and axle bearing are successful. Therefore, only the signals of bogie, which is the place to attach an accelerometer easily, is sufficient for the fault diagnosis and the safety evaluation of electric train. Also, adaptive interference canceling method can be applicable to evaluate the performance of vibration isolation between bogie and car body and to investigate the characteristics of indoor sound.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.4
• /
• pp.805-814
• /
• 2013

According to the shut-down of Analog TV service on 30th. December, 2012, UHF Digital Dividend Band (698~806MHz) could be used for Mobile service such as LTE(Long Term Evolution). In the condition that this band is allocated for LTE service, Interference evaluation between LTE and adjacent DTV service was carried out, using LTE-A system-level simulator which was developed for simulation of IMT-Advanced technology. If LTE service be commercialized in this band, this study proposes the coexistence condition through the interference evaluation such as the effects not only to DTV receiver from LTE terminal but also to LTE base station from DTV transmitter. It is expected that the coexistence condition by these studies will be applied to network algorism for IMT-Advanced system in this band.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.2
• /
• pp.143-148
• /
• 2006

The goal of this paper is to analyze, through simulations and experiments, GNSS interference mitigation performance under various types of antenna structures against wideband and narrowband interferences using spatial-temporal adaptive signal processing (STAP) techniques. The STAP approach, which combines spatial and temporal processing, is a viable means of GNSS array signal processing that enhancing the desired signal quality and providing protection against interference. In this paper, we consider four types of 3D antenna array structure - Uniform Linear Array (ULA), Uniform Rectangular Array (URA), Uniform Circular Array (UCA), and the Single-Ring Cylindrical Array (SRCA) under an interference environment. Analytical evaluation and simulations are performed to investigate the system performance. This is followed by simulation GPS orbits in interfered environment are used to evaluate the STAP performance. Furthermore, experiments using a 2x2 URA hardware simulator data show that with the removal of wideband and narrowband interference through the STAP techniques, the signal tracking performance can be enhanced.

• Journal of Communications and Networks
• /
• v.5 no.4
• /
• pp.354-364
• /
• 2003

A general method for the evaluation of the symbol error probability (SER) of ultra wideband (UWB) systems with various kind of modulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake receiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrowband interference (NBI) and that the value of the error floor is in-fluenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, representing a promising candidate for UWB systems. When the multiuser interference is dominant, all multiple access techniques exhibit similar performance under high-load conditions. If the number of users is significantly lower than the spreading factor, then DS outperforms both TH and OOC. Finally 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.

• Journal of Korea Society of Industrial Information Systems
• /
• v.6 no.4
• /
• pp.54-60
• /
• 2001

In this thesis, We analyze performance evaluation of one channel B-WLL IF receiver system. Among the item of receiver performance, inter-modulation interference and yield analysis is especially focused. Since inter-modulation interference cause bad influence on system performance due to unwanted third order harmonic located in desired frequency band, third order harmonic causing inter-modulation interference should be efficiently removed. Yield analysis is observing influence on system performance when system element parameter is statistically varied, and in this thesis, system output is observed for LNA parameters. Additionally, Scheme for LNA gain adjustment to reduce inter-modulation interference is proposed by observing variation of third order harmonic output for LNA gain variation.

• Journal of Internet Computing and Services
• /
• v.14 no.4
• /
• pp.13-24
• /
• 2013

IEEE 802.15.4 network and WiFi network are installed to overlap each other and configured to use adjacent frequency bands in which case the communication service required by applications can not be guaranteed because of randomly increased frame transmission delay and frequent frame transmission failures at nodes in IEEE 802.15.4 network. In this paper, transmission delay model at IEEE 802.15.4 nodes and an experimental system to evaluate the interference from WiFi traffic are described, then elements for the evaluation of interference are measured with the analysis of their characteristics. A sequential method of using medium access layer and physical layer elements of IEEE 802.15.4 protocols is proposed to decide interference from WiFi network. With the proposed method, if an evaluation function having frame transmission failures and transmission delay as variables returns a value greater than a threshold, intensive measurements of wireless channel power are carried out subsequently and the final decision of interference is made by the calculated average channel power. Experimental results of the method show that the decision time is reduced with increased frequency of decision in comparison to an other similar method.