• Journal of the Korea institute for structural maintenance and inspection
• /
• v.6 no.1
• /
• pp.241-254
• /
• 2002

Though there are many kinds of type in the expansion joint of bridges, Transflex joint was usually used from 1970's to 1980's. But it made of rubber is needed to exchange to new one often because of the breakage by wheel load. This study performed the safety estimation which is to exchange the transflex joint to finger joint kept the part of situ-cast-concrete. The standard of finger joint is same as that of transflex joint, we investigated the safety of finger joint with experimental results and FEM (Finite element method) analysis.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.74-76
• /
• 2002

The suspension insulators are subjected to harsh environment in service for a long time. Long term reliability of the insulators is required for both mechanical and electrical performances. We studied an analysing method to find out a deformation of brittle porcelain with a thermal expansion of cement for suspension insulator. These simulation analysis and experimental results show that cement volume growths affect severely to be mechanical failure ageing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.11
• /
• pp.895-901
• /
• 2012

In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical, electrical properties much improved EMNC_60 compared with EMNC_65.

• Journal of Power System Engineering
• /
• v.9 no.3
• /
• pp.26-32
• /
• 2005

The volumetric efficiency is significantly affected by the behavior of pressure wave in induction system and exhaust pipe. By the motion of the piston, there exist pressure fluctuation in induction system which produce waves. Waves are propagated along a pipe bi-directional as they propagated through it, making compression wave and rare-faction(expansion) wave. These wave phenomena can affect to the volumetric efficiency. As a method of improvement of the volumetric efficiency, fuel economy and pollutant emission reduction particularly in low engine speeds, a side-branch additional tunable helmholtz resonator on the secondary pipe of intake system is proposed by use of their acoustic vibrations. Some of results are presented which deal with their physical phenomena for the wave action of intake system in a four-stroke three cylinders diesel engine.

• Journal of Korean Society for Quality Management
• /
• v.24 no.2
• /
• pp.128-141
• /
• 1996

The advent of the quality-improvement movement caused a great expansion in the use of statistically designed experiments in industry. The regression method is often used for the analysis of data from such experiments. However, the data for a quality characterstic often takes the form of counts or the ratio of counts, e.g. fraction of defectives. For such data the analysis using generalized linear models is preferred to that using the simple regression model. In this paper we introduce the generalized linear model and show how it can be used for the analysis of non-normal data from quality-improvement experiments.

• Journal of the Korean Vacuum Society
• /
• v.12 no.4
• /
• pp.207-213
• /
• 2003

We have developed the hardware and software for automation of the national medium vacuum standard. The automation is necessary to control and monitor the complex system consists of several vacuum chambers, pumping systems, vacuum gauges, thermometers, and valves. By using the automation program, we have measured volume ratios of the system and performed calibration of a capacitance diaphragm gauge in order to evaluate the system.

• Journal of Welding and Joining
• /
• v.7 no.4
• /
• pp.46-55
• /
• 1989

Zirconia coatings are performed by the plasma spraying on the substrate of Al-Si alloy. In case of plasma sprayed ceramic coatings, it is important to control properly residual stress occurred during cooling process. Residual stress in coating layer varies with sprayed conditions and is influenced greatly by the coating layer thickness. Surface residual stress due to coating layer thickness is measured by X-ray diffraction method and the residual stress in coating layer is estimated by the deflection of coating layer when the restraint force in substrate was removed. When zirconia was coated on the substrate, tensile residual stress remains on zirconia coated surface layer. The tensile stress is increased to 0.35mm thickness and after 0.45mm thickness it is decreased abrouptly. A thick bond and composite coating reduce the zirconia surface stress and composite coating controls effectively the thick zirconia surface stress.

• Journal of Advanced Marine Engineering and Technology
• /
• v.7 no.1
• /
• pp.34-39
• /
• 1983

Development of modern internal combustion engine requires more precise indicator. In the case of strain gage-strain tube type indicator, thermal expansion of the indicator's fixed part makes zero-shift in spite of water cooling. Therefore, the authors analyzed the cause of zero-shift phenomenon on strain gage-strain tube type indicator and proposed a new device to compensate the zero-shift of indicator by electrical method without detoriorating the dynamic charcteristic. As the results, we found that the zero-shift is varied linearlly according to temperature variation of the indicator's fixed part and appling a new device, we can improve the zero-shift of indicator about 0.63% (0.63 kg/$cm^2$) of full scale, though we got 10% of it without the device at the cylinder head operating temperature (c.a. $200^{\circ}C$).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.781-785
• /
• 2005

Cutting forces and tool deflection in end milling are represented as the closed form of tool rotational angle and cutting conditions. The discrete cutting forces caused by tool entry and exit are continued using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping pan are considered for cutting forces and tool deflection estimation. Compared to numerical methods, the presented method has advantages in short prediction time and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the ferm accuracy is easily predicted by tool deflect ion curve.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.11
• /
• pp.1752-1759
• /
• 2004

Reinforced braid layer (RBL) in automobile power steering hose plays an important role in power steering system. When the working oil is applied to the power steering hose, RBL suppresses rubber hose deformation from internal pressure and heat expansion. RBL is woven textile composites having a double-row structure of nylon cords twisted with the specific helix angle. In this paper, effective material properties of RBL are estimated using a detailed 3-D finite element model considering its complicated geometry. Numerical experiments based on a superposition method are carried out to simulate uniaxial tensile loading condition.