• Transactions of Materials Processing
• /
• v.13 no.3
• /
• pp.242-247
• /
• 2004

Literature review on reliability test method for developing high performance optical/thermofluidic components. Since the miniaturization by the conventional mechanical process is limited to milli-structure, i.e. $10^{-3}m$, new technology for fabricating of mechanical components is needed to match cost, reliability, and integrability criteria of micro-structure. Although numbers of various researches on MEMS/MOEMS devices and components, including material characterization, design and optimization, system validation, etc., the lack of standards and specifications make the researches and developments difficult. For that reason, this paper is intended to propose the methods of reliability test for measuring the mechanical property of optical/ thermofluidic components.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.218-221
• /
• 1999

Many researchers make efforts to develope an effective material with anti-tracking property. Specially, the porcelain type insulator is required exchanging to polymer insulator according to the environmental consideration. In this paper, we have developed the estimation system using the translated IEC-60587 test for the application of actual insulator. Those approach has been very successful applied to the various practical insulator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.470-476
• /
• 2002

We tested the natural frequency for the 1st moving blades of a steam turbine in general power plants, carried out the modal test of the blade groups each natural frequency. By this test results, we identified the resonance results largely in damaging the blades. We can predict damage probability for the blade groups and change state of material property by using the result of this study.

• Journal of Ocean Engineering and Technology
• /
• v.23 no.3
• /
• pp.30-34
• /
• 2009

Oil hydraulic piston pumps are being extensively used in the world, because of simple design, light weight and effective cost etc. An oil hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency according to large time use. In the oil hydraulic piston pumps the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this paper, the wear property of the SACM645 material used the hydraulic piston pump has been work out by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, seven different types specimen were prepared. From the wear test results, induction hardening and nitration were definitely superior to the others. On the whole, nitration was estimated for high strength material to wear resistance.

• Current Photovoltaic Research
• /
• v.4 no.2
• /
• pp.59-63
• /
• 2016

A key point of a soldering process for photovoltaic (PV) modules is to increase an adhesive strength leading a low resistivity between ribbon and cell. In this study, we intended to optimize a heating condition for the soldering process and characterize the soldered joint via physical and chemical analysis methods. For the purpose, the heating conditions were adjusted by IR lamp power, heating time and hot plate temperature for preheating a cell. Since then the peel test for the ribbon and cell was conducted, consequently the peel strength data shows that there is some optimum soldering condition. In here, we observed that the peel strength was modified by increasing the heating condition. Such a soldering property is affected by a various factors of which the soldered joint, flux and bus bar of the cell are changed on the heating condition. Therefore, we tried to reveal causes determining the soldering property through analyzing the soldered interface.

• Journal of the Korean Society for Railway
• /
• v.8 no.6 s.31
• /
• pp.525-532
• /
• 2005

Fatigue life of catenary wires in various environments is reduced when stress is concentrated on some points, which are often found in corroded areas by surrounding pollutants. Therefore, the fatigue test were performed in order to investigate the effect of the surface corrosion on the destructive behavior in service environment and accelerated corrosion environment as well as th examine the corrosive property and mechanism of the catenary wires. In the fatigue test of the messenger stranded wire, the corrosion degraded materials showed 35~50% of fatigue life at a same stress amplitude compared to original material. Because the catenary wires have variable load by the interaction of periodic contacts with pantographs the maximum stresses of trolley wire and messenger wire calculated by simulation at the messenger wire during operation was estimated thought the corrosion behavior interpretation of variable stress and fatigue test.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.1 s.232
• /
• pp.81-87
• /
• 2005

A fracture of hand held device, such as radio, TV and CD-RW drive, mainly occurs due to drop situation. For CD-RW drive, the need of high reading/writing speed in conjunction with low price accelerates the fracture of the device. Computer simulation can reduce the period of development and enhance impact characteristic of device. In this study, the detailed finite element model of CD-RW drive was developed to predict the damage under drop conditions. Material property for shock absorbing damper was obtained from tensile test of raw material. A MOONEY-RIVLIN type rubber in LS-DYNA was used as the material model of damper. To assess the reliability of the developed model, drop test at 200G-2msec and 150G-10msec condition was conducted and acceleration at pick-up was compared.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.5
• /
• pp.45-51
• /
• 2010

This study is to evaluate an application of technology to the soft ground stability using quick lime pile in the field. We investigated properties of Korean quick lime by conducting loading test and theoretical consideration about a principle and property of soft ground improvement by quicklime. According to the test results, it was estimated that quick lime pile method has dehydration effect by absorption of quick lime, consolidation effect by swelling of pile, increasing bearing by strength of pile itself and decreasing sinking effect, etc. A material property of quick lime is favorable for construction and considerable strength. In the case of higher strength is required, using cement as additive would increase material strength.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.769-775
• /
• 2008

The objective of this report is to determine the difference of thermal response that grouted two different materials, and compare the simulation result of the length of total ground heat exchanger length that using the ground thermal conductivity. And also to know heat exchange variation of ground heat exchanger temperature that measured with various test depth. The result shows that the test hole grouted with water permeable material got better thermal response than grouted with water impermeable material. However, with consideration of ingnore for the initial 12 hour data, the test hole grouted with impermeable material has larger thermal conductivity than the other. By former thermal conductivity, simulated data by engineering program shows only 3.4% difference or less. This result shows that ground thermal conductivity is not the main variables for the design program of ground heat exchanger. At the cooling or heating mode, base on the depth of -150m, the ground heat exchanger has best temperature at $-90{\sim}-60m$ and than getting worse because of entering water heat exchanged with leaving water in the same hole.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1226-1228
• /
• 1995

This paper introduced foreign standard testing methods on composite insulators(for transmission, distribution) and mentioned on (1)evaluation of material property (2)short-term test of prototype (3)insulation efficiency on use to evaluation property of insulators made of composite insulating materials.