• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.2
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• pp.166-174
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• 1999

The flow characteristics of 2-valve and 4-valve cylinder heads with various blocked-valve were experimentally investigated in a steady flow rig. Effects of the blocked-valve configurations on flow coefficient, swirl and tumble intensity are studied. Compared to the conventional valve, the blocked valve in both cylinder heads have the much lower flow coefficient and the much higher intensity of swirl and tumble. Under the same size of blockage, the value of flow coefficient and swirl(or tumble) intensity were varied according to the position of blockage. Throughout these steady flow test the optimized positions of blockage in both cylinder heads were determined.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.31-37
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• 2016

In the steam system, a stream trap valve discharges a condensate and a non-condensable gas. It also prevents stream from being leaked. The free float stream trap valve is a mechanical type of stream trap. The valve is opened when a hallow ball is floated due to the density of the condensate through the condensate flows into the valve. On the other hand, when the flow of the condensate is completed, the valve is closed as the float subsides due to the weight of the structure and the stream is blocked. In addition, the bimetal lifts the hallow ball, which discharges the non-condensable gas. In this study, the performance of the properties of the free float stream trap valve, the method of support for three points, and the orifice design are researched. Moreover, the condensate discharge capacity of the free float stream trap valve is calculated from the experiment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.161-166
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• 2001

The static characteristics of four-nozzle flapper valves are investigated with both constant flow and constant supply pressure. The ranges, in which linearization of these characteristics would be valid, are discussed. Linearized dynamic model is also derived. Numerical simulations of nonlinear dynamic model are carried out by HyPneu to make an assessment of the effect of input step size in both cases of no-load and blocked-load operation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.720-727
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• 2008

Microfluidic single chip integrating thermopneumatic micropump and micro check valve are developed. The micropump and micorvalve are made of biocompatible materials, glass and PDMS, so as to be applicable to the biochip. By using the passive-type check valve, backward flow and fluid leakage are blocked and flow control is stable and precise. The chip is composed of three PDMS layers and a glass substrate. In the chip, flow channel and pump chamber were made on the PDMS layers by the replica molding technique and pump heater was made on the glass substrate by Cr/Au deposition. Diameter of the pump chamber is 7 mm and the width and depth of the channel are 200 and $180{\mu}m$, respectively. The PDMS layers chip and the heater deposited glass chip are combined by a jig and a clamp for pumping operation, and they are separable so that PDMS chip is used as a disposable but the heater chip is able to be used repeatedly. Pumping performance was simulated by CFD software and investigated experimentally. The performance was the best when the duty ratio of the applied voltage to the heater was 33%.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.387-394
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• 2017

This paper develops a pump system for patient with chronic pain or cancer. The pump module is consists of two micro-valve and membrane. The micro-valve is operated by a solenoid. With two solenoid valves which are connected via a drug transport line, the inlet and outlet are completely blocked. A silicon rubber membrane located between the two valves makes the flow-rate constant without any backflow. This pump module can control the flow-rate of drugs by controlling the time that the valves are opened and closed. The reservoir consists of a drug chamber and a gas chamber. As the gas chamber encloses the drug chamber, propellant gas which is injected into the gas chamber pressurizes the drug chamber regardless of volume of the drug chamber. To design the pump module, analysis a constant efficiency test, and accuracy test for the pump module were conducted.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.1
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• pp.49-55
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• 2015

In this study, among in various scenarios of the duration degradation of the fuel cell, countermeasures for the cathode carbon carrier oxidation and the deactivation of catalyst by hydrogen / air interface formation have been studied. so the system was applied to the air cutoff valve. In terms of the component, the cold start performance, electrical stability, the airtight performance were mainly designed and their performance was confirmed. And in terms of the system, the air electrode flow is blocked off, so the oxygen concentration drops when system is powered off, As a result, By reducing unit cell voltage which affect the durability of the fuel cell reached up to 0.8V, the improved durability of the fuel cell was confirmed.

• The Journal of the Korea Contents Association
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• v.20 no.6
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• pp.439-444
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• 2020

The purpose of this study is to seek an alternative method to prevent the contamination of normal saline caused by the back-flow of Gadolinium Based Contrast Agent(GBCA) by the use of auto-injector for dynamic MRI. The research method is to manufacture the non-return valve as an alternative to the existing, and to examine the usefulness of the normal saline by dividing the state of normal saline into three groups. The signal intensity were compared. As a result, there was no statistically significant difference between normal saline before injection of group 1 and group 3 non-return valve (p> 0.05). It is analyzed that the self-produced non-return valve completely blocked the GBCA back to normal saline when the GBCA was injected. In conclusion, the application of the non-return valve presented in this study for dynamic MRI imaging using the auto injector can prevent normal saline contamination due to GBCA back-flow.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.42-48
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• 1999

A control method for a robot hand grasping a object in a partially unknown environment will be proposed, where a proximate sensor detecting the distance between the fingertip and object was used. Particularly, the finger joints were driven servo-pneumatically in this study. Based on the proximate sensor signal the finger motion controller could plan the grasping process divided in three phases ; fast aproach, slow transitional contact and contact force control. That is, the fingertip approached to the object with full speed, until the output signal of the proximate sensor began to change. Within the perating range of the proximate sensor, the finger joint was moved by a state-variable feedback position controller in order to obtain a smooth contact with the object. The contact force of fingertip was then controlled using the blocked-line pressure sensitivity of the flow control servovalve for finger joint control. In this way, the grasping impact could be reduced without reducing the object approaching speed. The performance of the proposed grasping method was experimentally compared with that of a open loop-controlled one.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.182-188
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• 2009

The surface plasmon resonance ellipsometer (SPRE), using a multiple air injection system with an extraction of air system, has been proposed and developed to minimize measurement error of signals due to diffusion of reagent into running buffer. Since the diffusion of reagent into running buffer affects the refractive index of the running buffer by changing the concentration, characteristics of binding between various bio-molecules don't appear clearly in measurement results. The diffusion between running buffer and reagent can be blocked by using an air bubble injection system. An extraction of air system is used to remove the noise signal due to unnecessary air bubbles flowing in a channel. Reliability of measurement results has been improved by using the valve system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.136-140
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• 2006

We are developing a vol-oxidizer which transforms the spent $UO_2$ pellets into the $U_3O_8$ power through oxidizing process. The vol-oxidizer consists of furnace, filter, heater and valve etc. When the filter is blocked by the powder, the internal pressure of the furnace is increased owing to the air flow restriction. Then, the furnace vessel is swelled and deformed by it. In this paper, we proposed a procedure of the thermal analysis for furnace vessel design of spent fuel vol-oxidizer. In this work, we determined the thickness of the furnace through analyzing the internal pressure and the thermal stress of the furnace with respect to various pressure and temperature. To analyze the thermal stress, we used ANSYS 8.0 for constructing a FEM model of the furnace, and then analyzed it based on the ASME code. We also surveyed the material property and yield stress of SUS304 with various temperature. Analysis results are compared with the yield stress of the material. We manufactured the furnace and conduct the verification experiments.