• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.3
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• pp.126-130
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• 2016

Ti alloys have been used for orthopedic devices, automobile and aircraft because it has several beneficial properties such as a low density, a low modulus of elasticity, excellent high-temperature strength, excellent corrosion resistance and biocompatibility. In this study, Ti-64 composition (6 wt% Al, 4 wt% V) is investigated as a representative Ti-alloy system on the crystallographic characteristics and microstructure. We investigated crystal structure of the Ti-64 sample by XRD, and analyzed microstructure by compositional differences measured using FE-SEM and EDX.

• Composites Research
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• v.26 no.2
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• pp.105-110
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• 2013

In this study, we suggest the new floating PV generation structure which is improved the structural and economical efficiency compared with the system developed in the previous research. Pultruded FRP has superior physical and chemical material properties compared with those of conventional structural materials. Especially, pultruded FRP has an excellent corrosion-resistance, light-weight, and it also has high specific strength and stiffness which are highly appreciated for the design and fabrication of floating PV generation structure under harsh environmental condition. In this study, structural analysis using the finite element method has been performed to investigate the safety of new floating PV generation structure and newly applied structural members.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.1-7
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• 2004

The polyethylene pipe can use semi-permanent because of the high corrosion resistance with chemical stability. In addition to, there is the merit that is an easy to establish and to maintain. However, as the reason that it is simply degraded when the polyethylene pipe was exposed to the outside, mainly it is used to lay under the ground with low-pressure gas transportation pipe. In this study, the nondestructive evaluation method was used to maintain the integrity of the polyethylene pipe. We simulated the various defects on the polyethylene pipes, and then the AE signal occurred according to the impact test of steel ball was evaluated by the acoustic emission method. From the results, the waveform and dominant frequency could be distinguishing from the defect shapes of polyethylene pipe. Especially, in the case of notch defect, the AE signals occur different by the angle and depth of the notch.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.703-708
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• 2020

As the risk of earthquakes increases recently, earthquake-resistant designs were getting interest. For this reason, this study applies that Friction pendulum-type seismic isolator is a device that attenuates seismic energy by friction and pendulum motion. The friction pendulum-type seismic isolator of this study is very easy to transport, install and maintain with light weight of metal by applying the slider using high strength engineering plastic. In addition, there is an advantage that the corrosion resistance is very excellent compared to the existing metal parts. However, there is concern about long-term durability by replacing metal materials. In this study, the frictional pendulum-type seismic isolator with EP was applied to compressive-shear test, repeated fatigue test, and ultimate load test after fatigue test, and analyzed the deformation and shear or properties after the test. As the results, the adequacy of long term fatigue durability was experimentally proven.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.12
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• pp.1027-1035
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• 2016

In this study, a strain-controlled fatigue test of widely-used 316L stainless steel with excellent corrosion resistance and mechanical properties was conducted, in order to assess its fatigue life. Low cycle fatigue behaviors were analyzed at room temperature, as a function of the strain amplitude and strain ratio. The material was hardened during the initial few cycles, and then was softened during the long post period, until failure occurred. The fatigue life decreased with increasing strain amplitude. Masing behavior in the hysteresis loop was shown under the low strain amplitude, whereas the high strain amplitude caused non-Masing behavior and reduced the mean stress. Low cycle fatigue life prediction based on the cyclic plastic energy dissipation theory, considering Masing and non-Masing effects, showed a good correlation with the experimental results.

• Polymer(Korea)
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• v.24 no.3
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• pp.382-388
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• 2000

Polymer electrolyte films consisting of poly(vinylidenefluoride-hexafluoropropylene) (PVdF-HFP), LiClO$_3$ and a mixture of ethylene carbonate (EC) and ${\gamma}$-butyrolactone (GBL) were examined in order to obtain the best compromise between high ionic conductivity, homogeniety, dimensional and electrochemical stability. Measurements of ionic conductivity, differential scanning calorimetry and linear sweep voltammetry have been carried out for various compositions. The highest conductivity of 3.8$\times$10$^{-3}$ S$cm^{-1}$ / at 3$0^{\circ}C$ were obtained for a film of 30(PVdF-HFP)+7.8LiClO$_4$+62.2EC/GBL. From the DSC study, it has been found that the PVdF-HFP gels are stable up to 10$0^{\circ}C$, and the salt lowers the melting temperature of crystalline part of PVdF by interacting sensitively with polymer segments. When Lithium metal is in contact with the gel films, it tends to undergo corrosion and the reaction products accumulate resulting in the formation of a passive film on Li electrode. As the aging time progresses, the interfacial resistance increases continuously. Anodic stability is measured to extend up to about 4.5 V vs. Li.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.470-473
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• 2005

Spent nuclear fuels are regarded as a high level radioactive waste and they will be disposed in a deep geological repository. To maintain the safety of the repository for hundreds of thousands of years, the spent fuels are encapsulated in a disposal canister and the canister containing spent fuels should have the structural integrity and the corrosion resistance below the several hundreds meters from the ground surface. In this study, the concept of the spent fuel encapsulation process and the process equipment fur deep geological disposal were established. To do this, the design requirements, such as the functions and the spent fuel accumulations, were reviewed. Also, the design principles and the bases were established. Based on the requirements and the bases, the encapsulation process and the equipment from spent fuel receiving process to transferring canister into the underground repository including hot cell processes was established. The established concept of the spent fuel encapsulation process and the process equipment will be improved continuously with the future studies. And this concept can be effectively used in implementing the reference repository system of our own case.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.104-109
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• 2010

Lap joint friction stir welding(LFSW) is an relatively new solid state joining process. A6061-T6 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength to weight ratio and good corrosion resistance. Test methods used in this paper, lock-in thermography, a phase difference between the defect area and the healthy area indicates the qualitative location and size of the defect. In this paper, the defects detected from the thermal image of mechanical properties for weld were evaluated and compared by the lock-in infrared thermography technique.

• Journal of the Korean institute of surface engineering
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• v.31 no.3
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• pp.133-141
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• 1998

Stainless is widely used for various purposes due to its good corrosion resistance. There has been much research to produce the color stainless steel by several methods. In this experiment, TixN films have been deposited on the SUS304 substrate by the DC magnetron sputtering system and the color and texture of the films as a function of coating conditions has been studies. The TixN films showed a (111) preferred orintation in bias-free conditions. The texture of coated later was changed from (111) to (200) to (2200 with a change of the bias from -1000V to -3000V. When the bias is low, coated elements have low energy. Therefore, the texturct (111) of low surface energy. The mobility of atoms was increased with the increase of the blas and texture was changed to the other plane. Non-etched specimens all exhibited strong (111) texture. This result shows that (111) is a loose plane and of non-etched specimens all exhibited. High growing velocity of (111) of especially was main texture of Non-etched specimens. Low working pressure($4\times10^{-3}$torr) was more effective than figh working pressure ($6\times10^{-3}$torr) for the gold color of $Ti_xN$ film. L and b were increased and a was decreased with the increase of bias voltage. Accordingly, We obtained the near gold color of $Ti_xN$ film(L;92, a;1~1.5 b:24~29.50. As a result of reflectance. And as the bias increased, the reflectance was proportional to the increasing bias voltage, but we took the top reflectance when the bias voltage was -200V.

• Journal of Magnetics
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• v.5 no.4
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• pp.120-123
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• 2000

Co-Ni-Fe-N thin films were fabricated by a $N_2$ reactive rf magnetron sputtering method. The nitrogen partial pressure ($P_{N2}$) was varied in the range 0~10% . As$P_{N2}$ increases in this range, the saturation magnetization $B_s$ linearly decreases from 19.8 kG to 14 kG and the electrical resistivity ($\rho$) increases from 27 to 155 $\mu\Omegacm$. The coercivity $H_c$ exhibits the minimum value at 4% $P_{N2}$. The magnetic anisotropy fields ($H_k$) are in the range of 20$\sim$50 Oe. High frequency characteristics of $(Co_{22.2}Ni_{27.6}Fe_{50.2})_{100-x}N_x$ films are excellent in the range of 3$\sim$5% of $P_{N2}$. In particular, the effective permeability of the film fabricated at 4% $P_{N2}$ is 800, which is maintained up to 600 MHz. This film also shows Bs of 17.5 kG, $H_c$/ of 1.4 Oe, resistivity of 98$\mu\Omegacm$ and $H_k$ of about 25 Oe. Also, the corrosion resistance of $(Co_{22.2}Ni_{27.6}Fe_{50.2})_{100-x}N_x$ films was imp roved with increasing N concentration.