• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.173-177
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• 2012

The multilayer structure of glass/Ta(5.8 nm)/NiFe(5 nm)/Cu(t nm)/NiFe(3 nm)/FeMn(12 nm)/Ta(5.8 nm) as typical GMR-SV (giant magnetoresistance-spin valve) films is prepared by ion beam sputtering deposition (IBD). The coercivity and magnetoresiatance ratio are increased and decreased for the decrease of Cu thickness when the thickness of nonmagnetic Cu layer from is varied 2.2 nm to 3.0 nm. It means that the decrease of non-magntic layer is effected to the interlayer exchange coupling of pinned layer and the spin configuration array of free layer. For experiment of detecting and dropping of magnetic beads we used the GMR-SV sensor with glass/Ta/NiFe/Cu/NiFe/FeMn/Ta structure. From the comparison of before and after for the dropping status of magnetic bead, the variations of MR ratio, $H_{ex}$, and $H_c$ are showed 0.9 %, 3 Oe, and 2 Oe, respectively. The fabrication of GMR-SV sensor was included in the process of film deposition, photo-lithography, ion milling, and MR measurement. Further, GMR-SV device can be easily integrated so that detecting biosensor on a single chip becomes possible.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.4
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• pp.263-270
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• 2017

The shipbuilding industry uses large stationary tanks to store low-pressure air, which is used to open and close large shut-off valves. However, when supplying air from the tank to a distant valve, there are problems related to the need for supplementary pipes and the pressure drop during transportation. In this study, a portable welded vessel for storing high-pressure nitrogen (11 kg, 10 L, and 50 bar) was designed to prevent air leakage and improve the convenience of workers. This pressure vessel was elliptical to reduce the number of welded parts, which are structurally weak. The thickness and ratio of the major and minor axes of the pressure vessel were calculated to verify its structure stability at the working pressure (50 bar), and that the proposed weight and capacity were satisfactory. The residual stress caused by the welding process was calculated by performing a transient thermal-structural coupled field analysis using the ANSYS parametric design language (APDL), and the fatigue life of the vessel was verified based on the Goodman criterion.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.203-209
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• 1995

A study of the dependence of the magnetoresistance in $glass\[Cu_{x\AA}\NiFe_{50\AA}\Cu_{x\AA}\Co_{50\AA}](X;\=\;8,\;10,\;14,\;18,\;22,\;26,\;28,\;38,\;48,\;58\;\AA,\;N\;=\;2,\;3,\;4,\;10,\;20)$ multilayers prepared by dc magnetron sputtering on the interlayer thickness of Cu (X), the number of multylayer(N) and annealing temperature has been performed. Resistance measurement were made by four terminal method, and the magnetic field applied to perpendicular and parallel for the current. The maximum magnetoresistance(MR) ratio(%) was appeared in the vicinity of $10\;\AA$ in Cu layer, and it was oscillated with the thickness of Cu. The MR ratio was increased with the number of layers N, however the ratio for the N = 4 layers decreased rather than the N = 3 layers. The dependence of the ratio on the annealing temperature was increased to $250^{\circ}C$.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3026-3034
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• 2021

Multi-target X-ray tube is a new type X-ray source, and can be applied in many fields such as sensitive X-ray fluorescence analysis and medical imaging. In this work, we report an electric field modulation multi-target X-ray tube, which contains four targets (Cr, Ni, Au, Mo) coated on a Beryllium (Be) window. A four-valve electric field deflector was developed to deflect the electron beam to bombard the corresponding targets. Particle dynamics analysis software was employed to simulate the particle tracking of electron beam. The results show that the 30 keV electron beam could get a 6.7 mm displacement on the target plane by 10⁵ V/m electric field. The focus areas are about 2 mm × 5 mm and 4 mm × 2.5 mm after deflection in two directions. Thermal behavior calculated by ANSYS shows that the designed target assembly could withstand a 10 W continuous power. The optimum target thicknesses and emission spectra were obtained by Geant4 when the thickness of Be window was 300 mm and the electron beam incident angle was 0.141 rad. The results indicate that this multi-target X-ray tube could provide different X-ray sources effectively.

• Fire Science and Engineering
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• v.33 no.1
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• pp.99-104
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• 2019

In a gas system fire extinguishing system, extinguishing agents are usually stored with approximately 280 bar at $21^{\circ}C$ and are released at approximately 8 MPa through the decompression valve and orifice to quickly suppress the fire. When extinguishing agents are discharged, they cause a loud noise (approximately 140 dB), which can damage electronics, such as hard disk drives (HDDs). Therefore, the noise is becoming a serious issue in the gas extinguishing system. The method of the noise reduction by adding an absorbent is most general and in this study, the thickness of the absorbent was as a selected design variable. The noise level at the observation point and the flow characteristics inside the nozzle were numerically calculated and analyzed using the commercial code ANSYS CFX ver. 18.1.

• Corrosion Science and Technology
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• v.12 no.5
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• pp.227-232
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• 2013

A number of components installed in the secondary system of nuclear power plants are exposed to aging mechanisms such as FAC (Flow-Accelerated Corrosion), Cavitation, Flashing, and LDIE (Liquid Droplet Impingement Erosion). Those aging mechanisms can lead to thinning of the components. In April 2013, one (1) inch small bore piping branched from the main steam line experienced leakage resulting from wall thinning in a 1,000 MWe Korean PWR nuclear power plant. During the normal operation, extracted steam from the main steam line goes to condenser through the small bore piping. The leak occurred in the downstream of an orifice. A control valve with vertical flow path was placed on in front of the orifice. This paper deals with UT (Ultrasonic Test) thickness data, SEM images, and numerical simulation results in order to analyze the extent of damage and the cause of leakage in the small bore piping. As a result, it is concluded that the main cause of the small bore pipe wall thinning is liquid droplet impingement erosion. Moreover, it is observed that the leak occurred at the reattachment point of the vortex flow in the downstream side of the orifice.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.69-82
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• 1992

Vibration of intake menifold is important as it could worsen the noise levels radiated from surface itself and support bracket, and it eventually leads to the failures of a Throttle Position Sensor and an Idle Air Control Valve. In this study, structural modification method is proposed to reduce structural vibration of an intake manifold system. At first, vibration problems are identified through tests on a running engine. Then modal data acquired by modal testing and finite element analysis are helpful to understand vibration mechanism of the system, and used as the design guide when structural modifications are attempted. After the system model is validated by comparison of the modal data obtained from analysis and experiment, iterative calculations are performed to find optimized structure of the system by finite element analysis. As a result, a newly designed plenum bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is suggested in such a way that the intake manifold is stiffened, and that design of the support bracket is changed in terms of bolting position, thickness, shape, and minimum weight increase. Finally, it is shown that a new design achieves a significant reduction of vibration of an intake manifold system and it is confirmed by tests on a running engine.

• Journal of Biomedical Engineering Research
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• v.33 no.4
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• pp.202-206
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• 2012

In this study, we developed transdermal direct drug delivery device using micro-needle painlessly. We has fabricated micro-needle that is 130 ${\mu}m$ thickness and 250 ${\mu}m$length with 10 ${\mu}m$ spiral groove for rolling down drug. Head part of micro-needle device is composed of 20ea micro-needles, an on-off valve and a protective cap. Glass bottle for containing drug is connected to head part of micro-needle device. We examined the puncture characteristic testing using porcine skin and drug delivery testing using porcine, rat skin with Indian Ink.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.91-95
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• 1998

Exchange anisotropy between IrMn antiferromagnetic layer and NiFe ferromagnetic layer has been studied in IrxMn(100-x)/NiFe/Buffr/Si(100) films deposited by D. C. magnetron sputtering method. Among Zr, Ta, and Cu used as buffer layer, Zr and Ta enhanced the fcc(111) texture of NiFe and IeMn layer, but Cu did not affect microstructure of those layer. Strong fcc(111) texture of IrMn layer was confirmed to be the origin of exchange anisotropy of IrMn. Ir composition control in IrMn layer showed that {{{{ gamma -phase}}}} IrMn is stabilized between 10 and 30 at % Ir, an 21 at. % Ir in IrMn layer was optimum composition that showed maximum exchange anisotropy field. above 200 ${\AA}$ thickness of IrMn, antiferromagnetic property is stabilzed to show saturated exchange anisotropy field. Based pressure was confirmed to be critical requisite in IrMn-based spin-valve GMR 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.