• Proceedings of the KSME Conference
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• 2001.11b
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• pp.597-603
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• 2001

Control of pressure transients in a hydraulic system may be important and necessary to avoid failures and to improve the efficiency of operation. Flow restricting devices can result in a decrease in the peak pressure, but may change the response time. The response time has an important effect on both operator and operator perceived smoothness. The response time should correspond to how fast a system responds to a given disturbance at the system boundary. Occasionally the appropriate response time is not easily determined. This study is on the response time characteristics in the hydraulic system studied for the control of response time.

• Land and Housing Review
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• v.10 no.2
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• pp.53-58
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• 2019

Particulate matter (PM) is designated as a group 1 carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). In South Korea, the health threat caused by PM is the most serious level internationally. Therefore, in order to solve the urban PM problem, it is important to develop the technology that can control PM efficiently. In this study, CFD(Computational Fluid Dynamics) simulation was performed for PM pre-filter (type 1-3 with different PM collecting room) to develop a high-efficiency PM collecting device. The complex flow field and the local flow phenomenon inside the PM collecting device were understood with CFD simulation by changing the shape and size of the pre-filter. The PM removal performance can be described with flow rate through the device and PM removal efficiency. The type-1 pre-filter with 5x5 size collecting room was confirmed to have the highest efficiency. Based on the analysis results, the optimal type of pre-filter could be developed and it would be applied as an element technology included in the PM collecting device.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.89-94
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• 2002

In this paper, a Exhaust Flow Controller (EFC) technology for uniform application of film coater and developer device is introduced that spread and remove photo resister at semiconductor manufacturing process. Because developed EFC device uses differential pressure sensing method as a differential flow meter and embodied smart A/D conversion by using a one chip microprocessor and devised by feedback Servo control, It has shown excellent performance and stability evaluation, as maximum 2000L/min flow, capability of installation to actual semiconductor equipment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1249-1255
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• 2010

An ultra high- pressure system generally consists of a hydraulic power unit, an oil supply unit, an electrical power supply device, and an electrical control device. The hydraulic power unit supplies the hydraulic power to the intensifier to create generate ultra high pressure. The intensifier amplifies increases the pressure using the oil supplied from by the hydraulic power unit. The electrical supply devices and control devices maintain are provided for the electric motors, valves, and sensors. In this study, instead of a flow-control device, a pressure-control type device was mounted on a manifold block in the hydraulic power unit instead of the flow-control type. A servo valve was fitted in the intensifier, and the performance characteristics of the intensifier varied according to the variations of in the pressure cycle and with the temperature of the operating oil in the hydraulic power unit.

• International Journal of Control, Automation, and Systems
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• v.3 no.1
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• pp.100-108
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• 2005

This work presents a novel control index to regulate the pump speed of an axial flow blood pump for the left ventricular assist device (LVAD). The control index is based on the characterization of pump operating conditions such as normal or suction status. The pump operating characteristics reveal that a certain pulsatility relationship between the pump pressure difference and the pump flow is a unique index to identify the pump operating status under the diverse pump operating environments.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.40-42
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• 2010

Unsteady CFD results of the backward facing step (BFS) flow field is reconstructed by the low-dimenstional modes using the POD (Proper Orthogonal Decomposition) technique. Flow responses to the blowing or suction with various frequencies and amplitudes applied at the edge of the BFS can also be analysed using the same technique. The present technique can be effectively applied to the feedback flow control device.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.98-106
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• 2007

The vortex flow characteristics of a double-delta wing, which can change the incidence angle of its apex strake was investigated through the wing-surface pressure measurement and the particle image velocimetry(PIV) measurement of the wing-leeward flow region. The apex strake has sharp edges and can change its incidence angle with a hinge line at the 23% chord position measured from the apex of the main wing. The present study revealed that the incidence-angle change of the apex strake could greatly alter the vortex flow pattern around the double-delta wing and the wing-surface pressure distribution, which suggested that the apex strake could be used as an effective device for the active control of delta-wing vortex flow.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.143-146
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• 2015

Software Defined Network (SDN) separates control plane and data plane to achieve benefits such as centralized management, centralized provisioning, lower device cost and more flexibility. In SDN, scalability is an important issue. Centralized controller can be a bottle neck and many research tried to solve this issue on the control plan. However, scalability issue does not only happen in the control plane, but also happen in the data plane. In the data plane, flow table is an important component and its size is limited. In a large network operated by SDN technology, the performance of the network can be highly degraded because of the size limitation of a flow table. In this paper, we propose a ranking-based flow replacement method, Flow Table Management (FTM), to overcome this problem.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.855-856
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• 2008

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.310-313
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• 2006

The present study aims at investigating the effectiveness of a new passive cavity flow control technique, sub-cavity. The characteristics of cavity flow oscillation with the device are compared with those with other control techniques tested previously, including a triangular bump and blowing jet. In the computation, the three-dimensional, unsteady Navier-Stokes equations governing the supersonic cavity flow are solved based on an implicit finite volume scheme spatially and multi-stage Runge-Kutta scheme temporally. Large eddy simulation (LES) is carried out to properly predict the turbulent features of cavity flow. The present results show that the pressure oscillation near the downstream edge dominates overall time-dependent cavity pressure variations, and the amplitude of the pressure oscillation can be reduced in the presence of a sub-cavity.