• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2008년도 춘계학술대회
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• pp.135-147
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• 2008

The package loading process of the lumbering industry is an operation that after a pair of workers bind three or six lumbers into one unit and cut both ends of the lumbers, transports the weight cargo of 30-50kg by one meter, pack and load at a height of 1.2 meters. This package loading process causes lots of noise and wood dust when workers carry out the heavy work as the above. Therefore we developed the monolithic both ends cutting package loading equipment in order to prevent from getting musculoskeletal disease. An loading bar working system of this equipment is improved from pneumatic pressure system to oil pressure system, furnished the newly designed flow dividers, and developed the new system that a both end array is loaded identically. Also we developed the safety equipment of loading bar in order to prevent workers mistake and overload from malfunction during the package loading process. The main cause of job evasion on working place could be solved by preventing the musculoskeletal disease and improving the working environments.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.62.2-62.2
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• 2011

This study predicted broadband noise from a generic 2.5MW wind turbine blade in the time domain. The rotor blade was modeled as thin rectangular flat plates. A simplified analytic model proposed by Amiet was used to model the unsteady surface pressure distribution. The acoustic pressure was calculated by using the loading term of Formulation 1A proposed by Farassat. The validation was also performed by comparing with an experiment of Brooks, Pope, and Marcolini. By using these numerical methods, the broadband noise signal of the wind turbine was successfully predicted in this study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.579-583
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• 2001

Cause of noise/vibration for the sheet feeding apparatus of digital MFP is investigated by analyzing the measured sound pressure and the strategy for reducing the noise level is suggested. Factors related to the noise/vibration are found by loading test and the measurement of the noise by assembling the components. By checking the center distance between gears and the boss height, precision of assembly is identified as a main factor of noise. From the result of analysis, it can be concluded that the noise level of sheet feeding apparatus can be reduced by maintaining the distance between gears and the precision of assembly adequately.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.502-507
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• 2000

This paper presents the numerical prediction of airflow-induced sound in DVD drives. Computational fluid dynamics (CFD) is first conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. The acoustic analogy based on Ffowcs Williams-Hawkings (FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, resulting in a different pattern compared with those in the near field.

• 한국소음진동공학회논문집
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• 제16권10호
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• pp.1067-1073
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• 2006

In this paper, we present noise measurement results of 8 vehicles. The measurement was done by a close proximity method attaching surface microphones on the test vehicle. For the 9 road surface types constructed at Korean highway test road, the vehicles were tested from 50 to 120 km/h at the interval of 10 km/h in normal steady state and inertia cruising conditions. Using the results, we evaluate and discuss the effect of vehicle noise generation depending on the different conditions for vehicle type, speed, road surface and loading condition, especially focused on friction noise between tyre and road surface.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.428-433
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• 2006

In this paper, we present noise measurement results of 8 vehicles. The measurement was done by a close proximity method attaching surface microphones on the test vehicle. For the 9 road surface types constructed at Korean highway test road, the vehicles were tested from 50 to 120 km/h at the interval of 10 km/h in normal steady state and inertia cruising conditions. Using the results, we evaluate and discuss the effect of vehicle noise generation depending on the different conditions for vehicle type, speed, road surface and loading condition, especially focused on friction noise between tyre and road surface.

• 한국가시화정보학회지
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• 제21권3호
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• pp.39-48
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• 2023

In this study, we investigate the effects of slots installed on the tip of a rotor blade on aerodynamic characteristics. The slots weaken the strength and spatial coherence of the tip vortex at early vortex age and accelerate the dissipation of the generated tip vortex. Accordingly, the turbulence intensity of the rotor wake is reduced at both near and far wake, which leads to a reduction in broadband noise. Tonal noise is also reduced by mitigation of tip vortices, but tonal noise reduction is limited to a narrower range of azimuths than broadband noise due to the extinction of tip vortices. In addition, slots reduce both mean thrust and thrust fluctuations. Reduction in thrust fluctuations leads to a reduction in blade loading noise, resulting in a reduction in tonal noise.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.249-251
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• 2006

In this study, a systematic and effective tuning method of the actuator control parameters of the control loading system for aircraft based on control theory is presented. Firstly, to raise the time response of the system, the proportional gain and the integral gain of the velocity control loop is maximized within the range where vibration and noise does not occur. And then the position control loop is composed by getting the transfer function of the control loading system including the velocity control loop. With the root locus of the composed position control loop, the proportional gain of the position control loop that keeps stable transient state and leads good time response of the system is predicted, and the simulations are performed by using the predicted gain. Lastly, the actuator control parameters of actual control loading system are set to the previously obtained gain values. And the experiments to actuate the control loading system are executed. It shows that the tuning method of the actuator control parameter proposed in this study is applied to actual control loading system very well by comparing the results of the experiments with those of the simulations.

• 대한전자공학회논문지TC
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• 제46권2호
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• pp.18-26
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• 2009

송신단에서 채널 상태 정보를 알 수 있는 경우, 적응 알고리즘을 통한 전송 및 다중사용자 스케줄링을 통해 시스템 전송률을 향상시킬 수 있다. 본 논문에서는 비트 인터리버와 결합한 부호화된 직교 주파수 다중 분할 (BIC-OFDM; Bit-Interleaved Coded Orthogonal frequency Division Multiplexing) 기법을 기반으로 하는 다중안테나 (MIMO; Multiple-Input Multiple Output) 시스템을 고려한다. 먼저 Levin-Campello 알고리즘을 개선한 비트 로딩 (bit-loading) 기법을 제안하고, 이를 다중안테나 시스템으로 확장하여 한정된 개수의 신호 성상을 사용하는 데 따르는 잔여 파워 문제를 극복하는 알고리즘을 제시한다. 실험 결과는 제안하는 기법이 시스템 성능을 개선시키며 특히 높은 신호 대 잡음비 (SNR; Signal-to-Noise Ratio) 영역에서 기존의 기법에 비하여 큰 성능 이득을 제공함을 보여준다.

• 한국소음진동공학회논문집
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• 제22권2호
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• pp.179-186
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• 2012

The potential hazards resulting from a low-velocity impact(bird-strike, tool drop, runway debris, etc.) on aircraft structures, such as engine nacelle or leading edges has been a long-term concern to the aircraft industry. Certification authorities require that exposed aircraft components must be tested to prove their capability to withstand low-velocity impact without suffering critical damage. In most of the past research studies unloaded specimens have been used for impact tests, however, in reality it is much more likely that a composite structure is exposed to a certain stress state when it is being impacted, which can have a significant effect on the impact performance. And the radiated impact sound induced by impact is analyzed for the damage detection evaluation. In this study, an investigation was undertaken to evaluate the effect in-plane loading on the impact force and sound of composite laminates numerically.