• 한국기계연구소 소보
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• s.20
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• pp.41-48
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• 1990

Electro-pneumatic valves are an electro-mechanical device which convert electric signal into pneumatic flow rate or pressure signal. Recently, the development tendency of electro-pneumatic valve is to make the valve with more compact and less electric power consumption style. To make the valve such as a style, the role of solenoid part is very important. This paper is used in the finite-element method for the purpose of evaluating the magnetic property of solenoid and analyze flux distribution of solenoid theoretically. From flux contour line which is obtained by numerical analysis, it verified that the plunger shape and physical property of solenoid part have influence on saturation phenomenon and leakage of magnetic fluxs. This paper made an experiment on the measurement of dynamic response time and force in order to confirm the propety of analytic result, and confirmed a good agreement between analysis results and experiment results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.100-109
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• 1997

Tappet is the part which consists of valve train system in Over Head Valve type diesel engine. The role of tappet is to open and close the intake/exhaust valve by rotating with cam. There are wear problems like scuffing or pitting in cam/tappet system because of the higher Hertzian contact stress and sliding wear characteristics between cam and tappet. In this paper, to find optimal materials combination in cam/tappet system, wear test and rig test were performed. $Si_3N_4$, chilled cast iron, sintered alloy were selected for tappet materials. As the result of test, it is found that $Si_3N_4$ tappet has the excellent wear properties.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.121-122
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• 2012

In this research, we studied on improvement of the attraction force of solenoid operated valve for normal operation in harsh environment like vessel. Attraction force of the solenoid valves is effected by the B-H characteristics of magnetic material and the size of coil. In order to specify impact of the affection, we performed the B-H characteristics test and attraction force. Test results show that magnetic flux densities of the materials are difference each other more than 2 times in same magnetic intensity, and attraction force of the solenoid valve is 1.7 times difference as changes of resistance and the number of coil winding of solenoid.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.998-1002
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• 2008

The gel electrolytes were prepared with sulfuric acid and phosphoric acid, where hydrophilic fumed silica was used as a gelling agent. The influences of gel electrolyte on performance of the valve regulated lead acid (VRLA) batteries were investigated employing capacity tests, electrochemical impedance spectroscopy and scanning electron microscopy. The initial capacities of the sulfuric gel VRLA batteries were higher than that of phosphoric gel VRLA batteries. The sulfuric gel VRLA battery using 1.210 specific gravity of sulfuric acid with hydrophilic fumed silica exhibited the highest capacity of 0.828Ah. In the impedance measurements, the ohmic and charge transfer resistances for the phosphoric gel VRLA batteries were higher thanthat of sulfuric gel batteries. The morphology of electrodes of phosphoric gel VRLA batteries were more deteriorated in the SEM image.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.239-245
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• 2013

Modern electric controlled valves are demanded that its solenoid actuator should be smaller size, lighter weight, lower consumption power, and higher response time. For achieving these purposes, the major design factors of solenoid actuator such as magnetic flux density, coil turn numbers, plunger size, bobbin dimension, and etc. are must be optimized. In this study, for optimal design of high speed solenoid actuator for hydraulic servo valve operation, we draw up governing equations which are composed by combination of electromagnetic theories and empirical knowledge, and deduct the values of major design factors by use of them. For more increase the operating speed, voice coil are used as main armature in manufacturing of prototype actuator. And, we have proven the propriety of the governing equations and speed increasing method by experiments using the hydraulic valve assembly adopted the prototype of solenoid actuator.

• Journal of Magnetics
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• v.7 no.2
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• pp.55-58
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• 2002

MR transfer behaviors of the permanent magnet biased spin valve MR sensors with SyAF (synthetic antiferromagnet) layers were studied by micromagnetics modeling. For narrow track MR heads, various height to width ratios were considered together with strength of permanent magnets which stabilities the free layed As the MR sensor width is reduced to $0.12 \mu{m}$, sensor height less than 0.09 ${\mu}{\textrm}{m}$ is needed to show good linearity and the Mr.t of permanent magnets smaller than 0.2 memu/$cm^2$ is sufficient for the domain stabilization. The conditions for single domain behavior of the free layer were also investigated through optimizing the biasing strength of permanent magneto the shield gap and the aspect ratio of MR sensor.

• Transactions of Materials Processing
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• v.18 no.8
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• pp.607-616
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• 2009

There are three sub-processes associated with the assembly of the valve seat and cylinder head; heat fitting, cold fitting, and shrink fitting. In the heat fitting stage, the cylinder head is heated to a specified temperature and then squeezed toward the outer diameter of the valve seat. The cold fitting process cools the valve seat and safely squeezes it toward the inner diameter of cylinder head. However, these methods increased the installations & running cost and curtailed productivity. To address these problems, we analyzed the shrink fitting process using the contact pressure caused by fitting interference between the outer diameter of the valve seat and the inner diameter of the cylinder head. In this study, a closed form equation for predicting the contact pressure and fitting load is proposed. For quality control of the assembly line, principal factors of the shrink fitting process influenced in contact pressure were simulated by the FEM. Actual loads measured in the field showed good agreement with the results obtained by theoretical and finite element analysis.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.394-397
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• 2003

MTJ devices are fabricated using metal shadow masks and switching characteristics are investigated under 2 dimensional magnetic field. When the hard axis field is less than $\pm$ 16 Oe, switching behavior is similar to that based on the Stoner-Wohlfarth model. As the hard axis field is larger than $\pm$ 16 Oe, deviation from the expectation by Stoner-Wohlfarth model is observed. These phenomena are induced by the generation of multi-domain and inhomogeneous magnetization reversal.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.301-308
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• 2006

Today's automobiles are changing into miniaturization and light weight for saving natural resources and energies. In order to raise the sufficiency of fuel consumption, new mechanism and components are required. Therefore, the expectations on the new materials are very high. Especially, Al materials are widely used to reduce the motors weight. Al using in automobiles is mostly casting material, and the material is developing rapidly in step with technical innovation. Al die casting has become an important field, as we are turning today's motor into light weight. One of the parts in steering system, valve housing, plays a role to reduce the operating effort of drivers. If valve housing being a part of steering system is produced by gravity casting, the space that manufacturing equipments are installed will be increased, and more energies and workers will be needed.

• Korean Journal of Materials Research
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• v.14 no.2
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• pp.94-100
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• 2004

We have investigated the magnetic domain structure and the thermal stability of magnetotransport properties of IrMn biased spin-valves containing Co, CoFe and NiFe. The magnetic domain structures were imaged using a magneto-optical indicator film(MOIF) technique. To investigate the thermal stability, magnetoresistance(MR) was measured at annealing temperature(TANN) and room temperature($T_{RT}$) followed by the annealing. Domain imaging reveal that the increase of annealing temperature led to changes in the exchange coupling between the two ferromagnet(FM) layers through nonmagnetic layer rather than between FM and antiferromagnet. unlike the NiFe biased IrMn spin valve with large domains, MOIF pictures of Co and CoFe biased IrMn spin valve structures show the formation of many small microdomains. The magnetic structure, as revealed by the domain images, appeared unchanged while the MR dropped dramatically. From the combined giant magnetoresistance(GMR) and MOIF results, it was apparent that the decrease of MR ratio was not related to the spin valve magnetic structure up to about $350^{\circ}C$($T_{RT}$ ).