• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.251-255
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• 2005

By using liquid film thickness measurement the spray characteristics of swirl injector according to the geometric parameters were investigated in this paper. A specially designed injector having a variable backhole length, swirl chamber length, orifice length was used to measure the liquid film thickness. The spray characteristics of the injector were represented by mass flow rate according to the injection pressure, liquid film thickness in the lower orifice, spray cone angle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.63-68
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• 2013

The steam power plant is becoming more important to supply a stable power lately. Desuperheater of the steam power plant facility plays a role in maintaining the proper superheat to avoid damage turbine power due to the superheated steam produced in the boiler. In this study, when the steam flows $530^{\circ}C$, 36.7 kg/s, 1.36 MPa in the 460mm pipe, variable orifice nozzle developed in Korea was carried out the performance analysis in coolant injection conditions of $150^{\circ}C$, 4.28 MPa. Findings, steam pipe coolant temperature was maintained at $446^{\circ}C$ and sprayed droplet size was verified by $50{\mu}m$ or less.

• Journal of Drive and Control
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• v.16 no.1
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• pp.7-13
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• 2019

The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.192-200
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• 2002

Semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspensions for passenger cars. In this study, a continuous variable damper for a passenger car suspension is developed, which is controlled actively and exhibits high performance with light weight, low cost, and low energy consumption. To get fast response of the damper, reverse damping mechanism is adapted, and to get small pressure change rate after blow-off, a pilot controlled proportional valve is designed and analyzed. The reverse continuous variable damper is designed as a HS-SH damper that offers good body control with reduced transferred input force from tire, compared with any other type of suspension system. The damper structure is designed, so that rebound and compression damping force can be tuned independently, of which variable valve is placed externally. The rate of pressure change with respect to the flow rate after blow-off becomes smooth when the fixed orifice size increases, which means that the blow-off slope is controllable using the fixed orifice size. The damping force variance is wide and continuous, and is controlled by the spool opening, of which scheme is usually adapted in proportional valves. The reverse continuous variable damper developed in this study is expected to be utilized in the semi-active suspension systems in passenger cars after its performance and simplicity of the design is confirmed through real car test.

• Journal of Bio-Environment Control
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• v.5 no.2
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• pp.194-201
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• 1996

A series of experiments to analyse and to compare performance of various types of mini-sprinkler was carried out. Twelve kinds of the sprinkler, which have various sizes of nozzle orifice diameter and structures of spreader, were selected to be tested. Flow (water sprinkling) rate and sprinkling intensity pattern from a sprinkler were measured as a first part of this study, and the results are as follows. Sprinkler flow rate of various sizes of nozzle orifice and applied water pressures could be predicted by Torricelli's theorem. Discharge coefficients of the Torricelli's theorem for the sprinkler nozzle of various sizes were determined by the experiment as 0.90- 0.95, 0.80-0.82 and 0.76-0.79 for 0.8, 1.2 and 1.6 mm of nozzle orifice diameter, respectively. Experiments on sprinkling intensity pattern resulted that nozzle orifice diameter and applied water pressure are major variables for uniformity of the sprinkling intensity. More uniform sprinklering patterns were noted with smaller nozzle orifice diameter of a sprinkler and at lower sprinkling pressure. Besides the variables, structure of spreader of a sprinkler is also an important variable for the uniformity of sprinkling intensity.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.62-69
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• 2003

Swirl injectors have the advantage of stable combustion, high efficiency, and insensibility to variable O/F ratio. Recess length is the length from outer orifice tip to inner orifice tip. It is the very important variable of performance of swirl type injector Recess length have influence on collision, mixing, spray, and combustion of propellants. This study investigated on the engine performance with the change of recess length through CFD, cold flow test, and combustion test. In result, we could confirm the change of engine performance with the change of recess length. And we found that performance forecast process through CFD, cold flow test is the right process through combustion test.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.101-108
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• 2004

Recently, a semi-active shock absorber has been taking interest because of its low cost and simple structure than the active one. CFD analysis has been conducted to investigate the continuous and variable damping characteristics of the semi-active shock absorber. Also, the flow resistance characteristics of a spool valve has been examined to identify individual parameters(namely, exponent and discharge coefficient) of pressure-flow rate relation needed for the accurate valve modeling. The flow field in the damping valve was simulated using the commercial code, CFX-5.3. The numerical results showed reasonable agreement with the experimental outputs. The pressure distribution with the variation of spool opening length and volume flow rate were discussed in detail. And the continuous and variable damping performance was found clearly. The individual parameters of spool valve were obtained as a function of orifice area. The exponent and discharge coefficient were fitted in with the first and the third polynomial respectively.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.80-81
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• 1998

In this study, an experiments and numerical simulation of a three chamber pneumatic cylinder for an intelligent AK-knee prosthesis is performed. The cylinder has a variable orifice which can be controlled automatically through a microprocessor controller as needed while amputee gaits. In the experiment, the cylinder was driven by a cam whose trajectory of simulates the normal gait and axial forces of cylinder with different of orifice opening was measured. The numerical simulations was based on thermodynamic and fluid mechanical consideration. The experimental results and the numerical results were in good agreement.

• Applied Science and Convergence Technology
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• v.23 no.3
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• pp.103-112
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• 2014

The Korea Research Institute of Standards and Science (KRISS) has three major vacuum systems: an ultrasonic interferometer manometer (UIM; Section II, Figs. 1 and 2) for a low vacuum, a static expansion system (SES; Section III, Figs. 3 and 4) for a medium vacuum, and an orifice-type dynamic expansion system (DES, Section IV, Figs. 5 and 6) for high and ultra-high vacuum systems. For each system, explicit measurement model equations with multiple variables are given. According to ISO standards, all of these system variable errors were used to calculate the expanded uncertainty (U). For each system, the expanded uncertainties (k = 1, confidence level = 95%) and relative expanded uncertainty (expanded uncertainty/generated pressure) levels are summarized in Table 4. Within the uncertainty limits, our bilateral and key comparisons [CCM.P-K4 (10 Pa to 1 kPa)] are extensive and in good agreement with those of other nations (Fig. 8 and Table 5).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.373-378
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• 2000

Recently, it has been important to develop light, silent and less-vibrational automobile. In this study, in order to investigate the characteristics of the noise caused by the main silencer components-stiffener flange, inlet pipe and exhaust pipe etc., computational flow analysis, vibration and noise experiments were performed about the variable heights of the stiffener flange. Flow structure in the mainsilencer which calculated by CFD solver-IDEAS ESC, and frequency response function results of impact hammer test was proposed and it was found good agreement between former results and the exhaust orifice noise measured.