• Tribology and Lubricants
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• 제10권2호
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• pp.39-42
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• 1994

This paper deals with the distributions of the contact stress in oil seals. The distributions of the contact stress due to the temperature effects are analyzed for various values of the interference for a nitrile rubber seal. The calculated FEM results show that the relative maximum stresses occur at the contacting area against the shaft, the flex zone, and the contacting area of the garter spring grooves. Using the coupled temperature-stress FEM a nalysis, the contact force of a radial lip seal with and without the garter spring are studied as a function of shaft diameter. The calculated results of mechanical analysis show good correspondence with those of the coupled thermal-mechanical analysis method except small values of the interference. And the calculated results indicated that the thermal stresses only have a very minor influence on the deformed shape of the lip seal as the interference increases. But the coupled temperature-stress analysis will be very useful tool to predict the contact behaviors of rubber lip seals for small values of the interference.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 추계학술대회
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• pp.591-592
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• 2010

다양한 무선통신 시스템이 사용되고 있는 환경에서 수신 단으로 유입되는 강력한 인접 주파수 신호는 원래의 통신 신호 복원을 어렵게 할뿐만 아니라 시스템 성능을 현저하게 열화 시킨다. 따라서 이러한 인접 주파수 간섭을 제거하기 위한 기법을 본 논문에서 고찰하였다. 송신 단에서의 강력한 출력이 수신 단으로 유입되는 경우를 가정하였으며 구현이 비교적 간단한 일반적인 LMS 알고리즘을 이용하여 적응제거를 시도하였다. 적응계수들은 비교적 빠르게 수렴하였으며 $10^{-5}sec$ 정도 이내에 적응 제거가 이루어짐을 확인하였으며 50dB 정도의 제거성능을 보였다.

• 한국전산유체공학회지
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• 제10권2호
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• pp.60-68
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• 2005

For study on the unsteady wall interference effect, flows around a forced oscillating airfoil in closed test-section wind tunnels have been numerically investigated by solving compressible Navier-Stokes equations. The numerical scheme is based on a node-based finite-volume method with the Roe's flux-difference splitting and an implicit time-integration method coupled with dual time-step sub-iteration. The Spalart-Allmaras one-equation model is employed for the turbulence effect. The computed results of the oscillating airfoil having a thin wake showed that the lift curve slope is increased and the magnitude of hysteresis loop is reduced by the interference effects. Since the vortex around the airfoil is generated and convected downstream faster than the free-air condition, the phase of lift, drag and pitching moment coefficients was shifted. The pressure on the test section wall shows harmonic terms having the oscillating frequency contained in the wail effect.

• Journal of Communications and Networks
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• 제17권4호
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• pp.362-369
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• 2015

This study addresses the effects of channel estimation error and mutual interference between licensed and unlicensed systems on outage performance of reactive relay selection in unlicensed systems over independent non-identical (i.n.i) Rayleigh fading channels and under both the maximum transmit power constraint and primary outage constraint. Toward this end, power allocation for unlicensed users is first recommended to satisfy both constraints and account for channel estimation error and mutual interference. Then, we derive an exact closed-form outage probability representation for unlicensed systems to quickly evaluate this effect in key operation parameters. Various results corroborate the derived expressions and provide useful insights into system performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.354-356
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• 2001

The demand of the power and gas energy have been rapidly increasing with the industralization, therefore, the area where buried pipelines run parallel with the adjacent power lines and cross them increases in Seoul as well as other cities. These situation cause AC interference from the power lines. However, there aren't any standards to preserve the pipelines from AC interference in Korea. We just use other country's criteria directly. Other developed countries have used the various AC interference mitigation methods such as lumped grounding. cancellation wires and gradient control wires etc.. This paper introduces the steel plate method which is using for AC interference mitigation method in Korea and investigates the effects of mitigation methods through case study by computer simulation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.177-178
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• 2006

The real-time tracking system is an essential factor for the development of low cost sensor networks for use in pervasive computing and ubiquitous networking. In this paper, we address the interference problems of the sensor network platform with ultrasonic for location tracking system. Ubiquitous indoor environments often contain substantial amounts of metal and other such reflective materials that affect the propagation of radio frequency signals in non-trivial ways, causing severe multi-path effects, dead-spots, noise, and interference. Especially we present a novel reducing interference location system that is particularly well suited to support context-aware computing. The system called Pharos, aims to combine the advantages of real-time tracking systems that implement distributed environment with regardless of infrastructure or infrastructure-less wireless sensor networks.

• ETRI Journal
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• 제26권1호
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• pp.13-20
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• 2004

We propose a new optical code division multiple access (OCDMA) scheme for reducing multiple access interference (MAI) and enhancing performance for optical subscriber access networks using modified pseudorandom noise (PN)-coded fiber Bragg gratings with bipolar OCDMA decoders. Through the bipolar OCDMA decoder and the modified PN codes, MAI among users is effectively depressed. As the data are encoded either by a unipolar signature sequence of the modified PN code or its complement according to whether the data bit is 1 or 0, the bit error ratio (BER) can be more improved with the same signal to interference plus noise ratio over the conventional on-off shift keying-based OCDMA system. We prove by numerical analysis that the BER of the proposed bipolar OCDMA system is better than the conventional unipolar OCDMA system. We also analyze the spectral power distortion effects of the broadband light source.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.555-558
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• 2006

블루투스는 전자기기 사이의 연결성을 위한 근거리 무선통신 기술의 표준이다. 본 논문은 블루투스 시스템에서 동일채널간섭의 영향을 분석하였고 수신된 비트의 BER과 SIR을 기반으로 성능을 평가하였다. 다양한 채널상태를 나타내기 위하여 Eb/No와 SIR 값에 따라서 블루투스 시스템의 성능을 분석하여 결과 그래프에 나타내었다.

• International Journal of Computer Science & Network Security
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• 제22권4호
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• pp.223-228
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• 2022

Femtocells are being incorporated into heterogeneous networks in order to increase the network capacity. However, intensive deployment of femtocells results in undesired interference, which lowers the system's performance. Controlling the femtocell transmission power is one of of the aspects that can be addressed in order to mitigate the negative effects of the interference. It may also be utilized to facilitate the auto-configuration of the network's conductance, if necessary. This paper proposes the use of an auto-configuration technique for transmission power. The suggested technique is based on the transmission power of macrocells and the coverage provided by femtocells. The simulation findings show that the network's capacity has increased, and the amount of interference has decreased.

• 한국통신학회논문지
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• 제34권6A호
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• pp.468-475
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• 2009

Decode and Forward (DF) 방식을 사용하는 OFDM 기반 Full Duplex Relay (FDR)에서는 주파수 영역에서의 궤환 간섭 제거 방식이 더욱 효율적이다. 그러나 OFDM 기반의 FDR에서 궤환 간섭 신호 제거 및 복조를 주파수 영역에서 수행하는 경우 궤환 간섭 신호와 기지국으로부터 전송된 신호의 시간동기 불일치에 의한 인접 심볼간 간섭 및 인접 부반송파 간섭이 발생한다. 본 논문에서는 Synchronous 타입과 Asynchronous 타입의 OFDM 기반 FDR에서 시간 동기 불일치에 의한 영향을 하향링크와 상향링크에 대하여 분석한다. 주파수 영역 궤환 간섭 제거기를 갖는 FDR에서 간섭의 영향을 감소시킬 수 있는 동기화 절차와 기법을 제안하고, 모의실험을 통하여 그 성능을 확인한다.