• 한국분무공학회지
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• 제11권3호
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• pp.168-175
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• 2006

The static pressure distribution and flow characteristics inside the high-pressure swirl spray were investigated by measuring the static pressure inside the spray and applying the computational fluid dynamics (CFD). The static pressure difference between inner and outer part of spray was measured at different axial locations and operating conditions using a piezo-resislive pressure transducer. To obtain the qualitative value of swirl motion at different operating conditions, the spray impact-pressure at the nozzle exit was measured using a piezo-electric pressure transducer, and the flow angle was measured using a microscopic imaging system. The flow characteristics inside the high pressure swirl spray was simulated by the 1-phase 3-dimensional CFD model. The effect of pressure alternations on spray development was discussed with macroscopic spray images and a mathematical liquid film model. The results showed that the static pressure drop is observed inside the swirl spray as a result of the dragged air motion and the centrifugal force of the air. The recirculation vortex inside the spray was also observed inside the swirl spray as a result of the adverse pressure gradient along the axial locations. The results of analytical liquid film model and macroscopic spray images showed that the static pressure structure is one of the main parameters affecting the swirl spray development.

• 대한기계학회논문집B
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• 제31권3호
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• pp.283-291
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• 2007

The static pressure distribution, atomization characteristics and velocity distribution of tapered nozzle swirl spray is analyzed and then compared with original swirl spray. The static pressure distribution inside the swirl spray is measured using a piezoresistive pressure transducer. Phase Doppler anemometry (PDA) is applied to measure and analyze the droplet size and velocity distribution of tapered nozzle and original swirl spray. The static pressure inside the spray shows the lower value compared to the atmospheric pressure and this pressure drop is getting attenuated as the taper angle is increased. The droplet size of tapered nozzle spray shows similar value compared to the original swirl spray at the horizontal mainstream while it shows increased value at vertical mainstream. The deteriorated atomization characteristics of tapered nozzle spray is improved by applying high fuel temperature injection without causing the spray collapse. The velocity results show that the larger portion of fuel is positioned with higher injection velocity, and the smaller portion of fuel is positioned with lower injection velocity with causing spatially non-uniform mixture distribution.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.450-456
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• 2010

Shock absorber의 부품인 피스톤을 설계하기 위하여 저속용 피스톤에 가해지는 오일의 속도분포와 정압분포의 특성을 파악하였다. 오리피스를 통과하는 압축속도는 0.0156~0.0642 m/s를 나타났으며, 0.9 mm인 orifice의 속도분포와 정압분포 속도벡터는 속도가 클수록 회전하려는 경향이 커졌다. 0.8 mm인 orifice의 속도분포와 정압분포 속도벡터는 2차적으로 속도가 변하였고 두 번째 압력강하가 발생하였으며, orifice 근처 유선의 분포는 orifice 중심을 기준으로 와류가 발생하였다. 압축실에서 인장실로 통과하는 속도분포는 직경이 작은 orifice에서 속도가 크게 나타났으며, 압축실과 인장실의 압력차가 크면 클수록 피스톤에 작용하는 힘이 크게 나타났다.

• Wind and Structures
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• 제7권6호
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• pp.359-372
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• 2004

Wind tunnel model studies were carried out to determine the wind load distribution on tributary areas near the gable-end of large, low-rise buildings with high pitch planar and curved roof shapes. Background pressure fluctuations on each tributary area are described by a series of uncorrelated modes given by the eigenvectors of the force covariance matrix. Analysis of eigenvalues shows that the dominant first mode contributes around 40% to the fluctuating pressures, and the eigenvector mode-shape generally follows the mean pressure distribution. The first mode contributes significantly to the fluctuating load effect, when its influence line is similar to the mode-shape. For such cases, the effective static pressure distribution closely follows the mean pressure distribution on the tributary area, and the quasi-static method would provide a good estimate of peak load effects.

• International Journal of Fluid Machinery and Systems
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• 제9권1호
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• pp.95-106
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• 2016

A method of optimization design for the blade profile of a centrifugal impeller by controlling velocity distribution is presented, and a plenum fan is successfully designed. This method is based on the inner flow calculation inside the centrifugal impeller, and is related to the distribution of relative velocity. The results show that after optimization, the boundary layer separation on the suction surface has been inhibited and the stability of plenum fan is improved. The flow at the impeller outlet is also studied, and the jet-wake pattern at the impeller outlet is improved obviously by optimization. The calculation result shows that the static pressure and static pressure efficiency can be increased by 15.4% and 21.4% respectively.

• 대한물리치료과학회지
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• 제19권1호
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• pp.9-15
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• 2012

Background : The purpose of this study to find the Effect of TOGU Exercise on the Postural Balance and Foot Pressure Distribution. Methods : Four male and five female subjects last one year and no damage at all, even unique Foot skin diseases or orthopedic surgical disease who are not selected and applied before and after exercise TOGU and Foot Pressure Distribution of static equilibrium and measured using were compared. Results : After exercise conducted TOGU. right and life the static balance measurements of the height difference between the two sides of the acromion before exercise to 0.8cm and 1.4cm reduction in the movement, and also before and after the static balance measured sagittal the lateral tibial line drawn straight down from the earlobe and vertical slit in the distance before exercise from 5.8cm to 3.4cm decreased after exercise before and after the balance has also improved significantly(p<.05). Static balance of the body, according to the pressure of the foot in the exercise before/after there was no significant difference(p>.05). Conclusion : Dynamic shaking of the body have a positive impact on the static equilibrium could know that.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 춘계학술대회 논문집
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• pp.295-298
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• 2009

Bent duct 는 손실을 가중시키고, 효율을 저하시킨다. 지금까지 bent duct에 대한 많은 연구가 진행되었지만, 입구와 출구가 같은 형상에 대해서 연구가 되어왔다. 이번 연구에서는 입구는 환형이지만, 출구는 원형을 가진 bent duct에 대해서 진행되었다. 입구 속도 54 m/s, 레이놀즈수 238,000에서 수행된 이번 연구에서는 bent duct 바깥에 태핑홀을 배치하여 정압분포를 확인하고, 입구와 출구에서 5공 프로브로 유동을 측정하여 스트림 방향 속도 프로파일과 전압 손실 계수를 얻었다. 본 연구에서는 전압 손실 계수, 0.243를 얻었다.

• 대한통합의학회지
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• 제9권1호
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• pp.41-48
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• 2021

Purpose : The purpose of this study is to find out if it helps to improve static balance ability and weight bearing rate for chronic stroke patients with poor balance in clinical intervention through a method of correcting movement errors while performing a task by vibrotactile bio-feedback providing pressure information. Methods : Fifteen chronic stroke patients (12 male and 3 female) were participated in this study. To examine the effects of vibrotactile bio-feedback and general standing without bio-feedback on static balance ability and weight distribution symmetric index in all subjects randomized with R Studio. The static balance ability and weight distribution symmetric index of the participants was evaluated using a force plate. A paired t-test was used for comparison of each conditions. Statistical significance was set at α=0.05. Results : The comparisons of static balance ability and weight distribution symmetric index in chronic stroke patients after two different condition are as follows. In the static balance ability and weight distribution symmetric index, the vibrotactile feedback providing pressure information showed a significant difference compared to none feedback (p<.001). Conclusion : The vibrotactile bio-feedback providing pressure information in real time can support an improve in static balance ability, uniform weight bearing rehabilitation in chronic stroke patients. In the future, it is hoped that a follow-up study that provides a better direction of intervention compared to various feedback interventions commonly used in clinical practice.

• 한국공간정보시스템학회:학술대회논문집
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• 한국공간정보시스템학회 2004년도 춘계 학술발표회 논문집 제1권1호(통권1호)
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• pp.245-251
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• 2004

This paper discuss the conditionally sampled actual wind pressure distributions causing peak quasi-static wind loads in the large span roofs using the wind pressures at many locations on dome models measured simultaneously in a wind tunnel. The actual extreme pressure distributions are compared itk load-response-correlation (LRC) method and the quasi-steady pressure distributions. Based on the results, the reason for the discrepancy in the LRC pressure distribution and the actual extreme pressure distribution are discussed. Futhermore, a brief discussion is made of the equivalent static wind load estimation for the large span roofs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1120-1124
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• 2007

Recently in the automotive brake industry brake squeal noise has become one of the top automotive quality warranty issues. The contact pressure is used to predict friction coupling in the brake squeal analysis. The formulation of friction coupling has performed by nonlinear static analysis prior to the complex eigenvalue analysis. This paper proposes a validation methodology of squeal analysis using modal testing and contact analysis and examines the effect of predicted contact pressure that leads to the discrepancy between unstable complex mode and squeal frequency. This studies compose a three step validation process : examining the modal characteristics of component and assembly loaded contact pressure using modal testing and FEM analysis and verifying the contact pressure distribution using nonlinear static analysis and experiment. Finally, the unstable modes from complex eigenvalue analysis and realistic squeal frequency from the noise dynamometer are investigated.