• Wind and Structures
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• 제3권4호
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• pp.255-266
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• 2000

Wind-induced interference effects on a building are the result of one or more adjacent buildings modifying the flow of wind around it, which may result in a significant increase or decrease in wind loads on the building. Wind loading standards and codes of practice offer little guidance to the designer for assessing the effects of interference. Experimental results on interference effects indicate that code recommendations may be significantly low (unsafe) or uneconomically conservative. The paper presents results of an extensive experimental program to study the wind flow mechanisms and to quantify the extent of wind load modifications on buildings due to interference effects. These results have been simplified and presented from the point-of-view of design and codification for the case of two buildings. Based on these results, general guidelines and limiting conditions defining wind interference are formulated and discussed.

• Wind and Structures
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• 제8권3호
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• pp.163-178
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• 2005

Wind-induced mean and dynamic interference effects of tall buildings are studied in detail by a series of wind tunnel tests in this paper. Interference excitations of several types of upwind structures of different sizes in different upwind terrains are considered. Comprehensive interference characteristics are investigated by artificial neural networks and correlation analysis. Mechanism of the wakes vortex-induced resonance is discussed, too. Measured results show significant correlations exist in the distributions of the interference factors of different configurations and upwind terrains and, therefore, a series of relevant regression equations are proposed to simplify the complexity of the multi-parameter wind induced interference effects between two tall buildings.

• 한국항행학회논문지
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• 제7권1호
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• pp.22-29
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• 2003

본 논문에서는 성층권 통신 시스템(HAPS : High Altitude Platform System)과 NGSO (Non-Geostationary Orbit) 시스템간 간섭 영향을 두 가지의 경우로 나누어서 분석한다. 한가지는 HAPS 시스템이 NGSO 시스템에 미치는 간섭이며, 다른 한가지는 NGSO 위성이 HAPS 시스템에 미치는 간섭 영향이다. 그 결과 NGSO 이동국이 받는 간섭은 NGSO 위성 위치가 $95^{\circ}$일 때 가장 높게 나타났으며, 이때 HAPS와 NGSO 모두에 의한 간섭은 사용자 수가 20명 이상부터 간섭 기준을 초과함을 알 수 있었다. 그리고 HAPS 이동국이 받는 간섭의 경우에는 NGSO 위성 앙각이 $87^{\circ}$일 때 가장 높은 간섭이 나타났으며, 이 때 NGSO와 HAPS 모두에 의한 간섭은 사용자 수가 10명 이상부터 간섭 기준을 초과함을 알 수 있었다. 또한 $64^{\circ}$일 때 가장 낮은 간섭이 나타났으며, 이때 NGSO와 HAPS의 사용자 수가 같을 경우에는 190명에서부터 간섭을 초과함을 알 수 있었다.

• International Journal of Precision Engineering and Manufacturing
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• 제4권4호
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• pp.32-38
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• 2003

An analytical model of the interference phenomena in the centerless grinding process is developed to investigate their effects on the roundness profile of a centerless ground workpiece. In this work, the regulating wheel and work-rest blade interferences are modeled as a single point contact. The grinding wheel interference is modeled as multiple points contact because material removal is determined by the duration of contact. The computer simulation results show good agreement with the experimental data. From this work, the existence and effects of the interference phenomena in the centerless grinding process are found.

• 조명전기설비학회논문지
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• 제25권12호
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• pp.88-93
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• 2011

When the ground current is injected into the adjacent ground electrode, the potential interference is caused between ground electrodes, the ground potential interferences have been largely studied with power frequency fault currents. Many attempts to find the frequency-dependent grounding impedance report that the high frequency grounding impedance is very different with the ground resistance. This paper presents experimental data on the frequency-dependent potential interference effects in the vicinity of ground rod. The ground potential rises around the test ground rod of 4 or 6[m] were measured and discussed. As a result, the ground potential rises and potential interference factor are decreased with decreasing the grounding impedance. It was found that the lowering of grounding impedance is critical to reduce the ground potential interference effects.

• Wind and Structures
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• 제8권3호
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• pp.147-161
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• 2005

Two identical tall building models with square cross-sections are experimentally studied in a wind tunnel with high-frequency-force-balance (HFFB) technique to investigate the interference effects on wind loads and dynamic responses of the interfered building. Another wind tunnel test, in which the interfered model is an aeroelastic one, is also carried out to further study the interference effects. The results from the two kinds of tests are compared with each other. Then the influences of turbulence in oncoming wind on dynamic interference factors are analyzed. At last the artificial neural networks method is used to deal with the experimental data and the along-wind and across-wind dynamic interference factor $IF_{dx}$ & $IF_{dy}$ contour maps are obtained, which could be used as references for wind load codes of buildings.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.26-51
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• 2009

In this paper, we propose an empirical framework for modeling and emulating interference in multi-hop wireless ad-hoc networks. Wireless interference causes wide variation in the frame delivery rate at a link, and thus we cannot represent the state of the link with only two states, connected state and disconnected state, as in wired networks. We first investigate wireless interference in detail, in order to accurately calibrate the interference and identify its underlying attributes, and then we simulate the diverse occurrences and effects of interference, after incorporating the scheme into a simulation tool. Based on these observations, we devise a modeling and simulation framework with several control parameters, and perform an extensive set of simulation studies. The simulation results indicate that the proposed framework enables us to examine various attributes of wireless interferences and their effects on wireless network protocols and systems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.402-409
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• 2008

Wind loads and environments in realistic situations surrounded by neighboring buildings may be considerably different from those in idealized or simplified situations such as codes and standards. Interference effects of change in wind passage of a building group on wind loads and wind environments are reviewed. Wind-induced interference effects depend mainly on the building geometry and arrangement of these structures, their orientation and upstream terrain conditions. The most important factor among them may be the arrangement of building structures which can change the wind direction directly. Interference effects regarding wind loads are discussed with examples of window damages by typhoon and of pressure measurements in the boundary layer wind tunnel. Wind environment problems are also discussed, specially underlined on pedestrian comfort and safety. Various evaluation techniques or standards of wind environment are introduced. The change of wind velocity between the panel-type apartment buildings is examined, depending on the distance each other.

• 한국항행학회논문지
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• 제4권2호
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• pp.182-190
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• 2000

본 논문은 HAPS와 이동위성 시스템과의 간섭영향 분석으로서, HAPS 고도가 20km와 50km일 때의 C/I 값을 구해 간섭 보호비를 초과하는 시간율 및 초과지속시간에 대한 평가를 행하였다. 그 결과 HAPS가 Iridium 시스템에 미치는 간섭의 경우 최저 C/I 값은 HAPS 고도가 50km일 때 20.42dB, 20km일 때는 12.73dB로 낮아지고, 이와 반대인 Iridium 시스템이 HAPS에 미치는 간섭의 경우도 각각 13.94dB에서 10.42dB로 낮아짐을 알 수 있었다. HAPS 고도에 따른 간섭영향을 보면, 고도가 낮아질수록 강한 간섭을 주거나 받게 되며, C/I 최저값 또한 HAPS 고도에 따라 다른 시점에서 나타난다.