• 한국정밀공학회지
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• 제22권4호
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• pp.44-51
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• 2005

In this paper, a new polishing head with the variable pressure structure was studied to improve the planarization uniformity of the conventional template-metal head. Metal surface waviness and slurry distribution on the pad have been known to affect the polishing uniformity even in the synchronized quill and platen velocities. A polishing head with silicon rubber sheet was used to get a curved pressure distribution. In the experiment, the vertical deflection behavior on the pad was characterized with back pressure in the air chamber. Quill force increased linearly with backpressure. However, backpressure under a quill force made the upward movements of the quill. In the wafer polishing experiments, polishing rate and polishing thickness distribution were severely changed with backpressure. The best uniformity was observed with the standard deviation off.5％ level of average polishing removal 215nm at backpressure 12.1kPa.

• Journal of Power Electronics
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• 제9권3호
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• pp.491-498
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• 2009

The hydraulic-oil pump is widely used for building machinery, brake systems of vehicles and automatic control systems due to its high dynamic force and smooth linear force control performance. This paper presents a novel direct instantaneous pressure control of the hydraulic pump system with SRM drive. The proposed hydraulic pump system embeds the pressure controller and direct instantaneous torque controller. Due to the proportional relationship between pump pressure and torque, pressure can be controlled by the motor torque directly. The proposed direct torque controller can reduce inherent torque ripple of SRM, and develop a smooth torque, which can increase the stability of the hydraulic pump. The proposed hydraulic pump system has also fast step response and load response. The proposed hydraulic pump system is verified by computer simulation and experimental results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.228-233
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• 2005

Two-dimensional Stokes flows through a micro channel with a couple of symmetric vertical fins are investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The slip boundary conditions are applied to take account of the Knudsen number effects. For the analysis, the method of eigen function expansion and collocation method are employed. By the results, the streamline patterns and pressure distributions are shown and the force exerted on the fin and the excess pressure drop due to the fins are determined as functions of the length of the fin and Knudsen number. It may be conjectured that the force and the excess pressure drop are almost independent of the Knudsen number.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.301-301
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• 2000

It is well known, for many years, that deep drawability ,can be improved by applying variable blank holding force. To apply variable blank holding force during cup during, we set up pressure controlling system on experimental hydraulic press, and the pressure control system is often called NC(Numerically Controlled} cushion system. Using the NC cushion system we carry out pressure control experiment and the proposed structure shows good performance. And we compare drawability of square steel cups with NC cushion and that with conventional cushion. The results show drawability is greatly improved when the pressure control curve is designed in a S-shaped curve. This paper includes design details of the NC cushion system and experimental analysis of drawability with experimental NC cushion system.

• 수산해양교육연구
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• 제9권1호
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• pp.40-48
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• 1997

In this study, uniform pressure distribution with small hole on the surface of symmetric object were given to reduce the viscous frictional force. The results were as follows : 1. The velocity on upper stream were accelerated by uniform pressure distribution on symmetric objects for reducing the viscous frictional resistances. 2. The effects of the distributed small holes were reduced the viscous frictional resistances in down stream region more than upper stream due to the increasing pressure in reverse flow region. 3. The viscous skin friction on surface of symmetric objects with and without distributed small holes are effect in region of upper stream and much decreased in down stream region due to increasing of boundary layer thickness.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.93-94
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• 2016

The resistance of crowd pressure is an important performance to be influential on safety of facility users among performances required for light weight walls of public facilities. This study has empirically evaluated the estimation of size of crowd pressure to be applied to a wall of structure. For the load analysis test, the force plate with stiffness of 28 kN/cm was designed and manufactured. For inspectors, 15 males in the age of 20s were selected. The action of putting load was set as instantaneous push of plate and continuous push. As the load was increased linearly from the weight of inspector, the size of load was indicated as the load ratio. In case of instantaneous force, about 1.18 times the weight of pushing personnel was acted as a load. In case of continuous push, about 0.80 times the weight of pushing personnel was acted as a load.

• 유공압시스템학회논문집
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• 제6권2호
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• pp.22-30
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• 2009

An in-process method of diagnosing the spool wear of hydraulic servovalves was explored. The diagnostic method discussed in this paper is for force-control hydraulic servo systems. The key principle used is that pressure sensitivity of a servovalve drops as the valve spool wears out so that it is possible to determine the spool condition by monitoring pressure sensitivity. A diagnostic algorithm was developed and evaluated through numerical simulation and experiments. Two major steps of diagnosis are the evaluation of null bias of the servovalve and the approximation of pressure sensitivity, both of which could be successfully done during normal operation of a servo system. The difference between a new servovalve and a worn valve could be clearly detected in-process, and the diagnostic test was found to be repeatable.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1041-1046
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• 2004

A proportional pressure control valve has a nonmagnetic ring which is inserted in between a coil and plunger and it can get attraction force in proportion to input current by an influence of control cone. Therefore, a proportional pressure control valve is applied to a servo system as substitution of servo valve and an on-off solenoid valve widely because control of a high level is possible and pollution level is low. The purpose of this study is to develop domestic model of a proportional pressure control valve, and a test model was designed and manufactured through valve system analysis and finite element analysis. And comparison between results of theoretical analysis and static / dynamic characteristics test were carried out on a manufactured test model, and it was confirmed that it has excellent performance in comparison with other foreign products.

• 대한안전경영과학회지
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• 제23권4호
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• pp.43-48
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• 2021

In this study, the experiment was conducted on a fire door(W × H = 0.98 m × 2.19 m) installed on the vestibule. The effective leakage area for each opening angles and closing forces derived from the impulse-momentum equation was compared and analyzed with the experimental results. As a result of the experiment, the major factors affecting the door closing forces were the pressure difference and the area of the door. The difference of door closing forces between measured and calculated values by the impulse-momentum equation showed a deviation of less than ±15% at the opening angles of 5°to 10°. At the door opening angle of 2.5°, the dynamic pressure was much higher than the measured static pressure, and this pressure difference is estimated to be air resistance acting to prevent the door from being completely closed.

• Journal of Oral Medicine and Pain
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• 제31권3호
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• pp.265-274
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• 2006

측두하악관절 내장증, 그 중에서도 정복성 관절원판 변위(Disc displacement with reduction; DDwR)는 가장 흔하게 발생하는 측두하악관절 질환으로, 저작 능력에 다양한 영향을 미칠 것으로 생각되어져 왔다. 저작 능력을 평가하는 객관적이고 가시적인 수단으로 최대 교합력의 측정이 널리 통용되어져 왔는데, 과거 많은 연구자들이 측두하악장애(TMD)와 교합력의 관계에 대한 연구를 시도하였으나, 피험자의 개인적 특성이나 측정 방법의 차이 등으로 인하여 통일성 있는 결과를 얻지 못하고 있으며, 측두하악장애로 인한 통증이 교합력 및 저작능력을 감소시킨다고 보고된 바 있으나 측두하악관절의 구조적 변화와 저작능력의 관계에 대한 연구는 아직 충분히 이루어져 있지 않다. 본 연구에서는 측두하악관절의 구조적 변화와 저작 능력의 관계를 파악해 보고자 개구시 무통성의 관절음을 보이는 환자 39명 및 대조군 59명을 대상으로 최대 교합력, 교합 접촉 면적 및 교합압을 감압필름법(pressure sensitivie film)을 이용하여 분석, 평가한 후 다음과 같은 결과를 얻었다. 1. 정복성 관절원판 변위 환자군이 대조군보다 높은 최대 교합력(P < 0.01) 및 넓은 교합 접촉 면적(P < 0.05)을 나타내었다. 2. 단위 면적당 평균 교합압은 대조군과 정복성 관절원판 변위 환자군 간에 있어서 유의성있는 차이를 보이지 않았다(P > 0.05). 3. 남녀간의 차이에 있어서, 정복성 관절원판 환자군과 대조군 모두에서 남성이 여성보다 높은 교합압을 나타내었으나(P < 0.05), 평균 교합압과 교합 접촉 면적은 유의성있는 차이를 보이지 않았다(P > 0.05). 이상의 결과로부터 얻을 수 있는 결론은 측두하악관절의 정복성 관절원판 변위가 교합 기능을 변화시키는 한 요소로서 작용할 수 있다는 점이다. 향후의 연구에 있어서 근전도 등을 이용한 저작근 활성도 측정을 병행함이 유용할 것으로 사료되며, 교합력에 영향을 미치는 다른 요소가 통제된 보다 대규모 환자집단에 대한 연구가 필요할 것으로 사료된다.