• Transactions of the Korean Society of Mechanical Engineers A
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• 제33권2호
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• pp.162-168
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• 2009

In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that delamination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested.

• Proceedings of the KSME Conference
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• 대한기계학회 2008년도 추계학술대회A
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• pp.216-221
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• 2008

In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that determination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested

• Journal of Welding and Joining
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• 제16권4호
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• pp.92-97
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• 1998

Because of the low melting temperature of solder, each temperature cycle initiates an irrecoverable creep deformation at the solder interconnection which connects the package body with the PCB. The crack starts and propagates from the position where the creep deformation is maximized. This work has tried to compare and analyze the thermal fatigue life of solder interconnection which is affected by the lead material, the size of die pad, chip thickness, and interface delamination of 48-Pin TSOP under the temperature cycle ($0^{\circ}C$~1$25^{\circ}C$). The crack initiation position and thermal fatigue life which are calculated by using FEA method are well matched with the results of experiments. The thermal Fatigue life of copper lead frame is extended around 3.6 times longer than that of alloy 42 lead frame. It is maximized when the chip size is matched with the length of the lead. It tends to be extended as the thickness of chip got thinner. As the interfacial delamination between die pad and EMC is increased, the thermal fatigue life tends to decrease in the beginning of delamination, and increase after the delamination grew after 45% of the length of die pad.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제10권6호
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• pp.109-115
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• 2001

This paper investigates the mechanical characteristics of angle-ply laminates with non-woven carbon tissue. The lami- nates were made by inserting non-woven carbon tissue at the interface. Specimens were rounded near the tabs by grinding and polishing to reduce the stress concentration. Cyclic loads were applied to the specimens and the stress and fatigue life curves were obtained. The matrix crack density was also evaluated to check the effects of non-woven carbon tissue on the fracture resistance of composite laminates. C-Sean technique was used to evaluate the delamination, and SEM was used to understand the fracture mechanisms of the laminates. Experimental results show that the fatigue strength and life of composite laminates were increased by inserting non- woven carbon tissues. The results also show that the matrix crack density and delamination area were reduced by inserting non-woven carbon tissues.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제18권4호
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• pp.401-409
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• 2009

This paper presents a method of calculating the stress intensity factor (K) and crack propagation direction (${\theta}_0$) at the crack-tip that is associated with delamination in the large scale integration(LSI) package. To establish a reasonable strength evaluation method and life prediction, it is necessary to assess fracture parameters under various fracture conditions. Therefore, we conducted quantitative stress singularity analysis considering thermal stress simulating the changes of crack length (a), (h) and (v) in delamination using the 2-dimensional elastic boundary element method (BEM), and from these results predicted crack propagation direction and path.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.15-20
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• 2006

Real time health monitoring system was studied to detect the . generation of defects in the composite structures during service life. The PZT sensors were embedded into the woven-glass/phenol composite plate during the fabrication. VARTM (Vacuum Assisted Resin Transfer Molding) process were used to fabricate the composite plate. A Teflon tape was embedded between glass fiber layers to mimic delamination induced during service. Normalized maximum amplitude and energy analyses were used for the acquired signals. Both amplitude and energy of acquired signals were extremely sensitive to the delamination. Therefore, it was successful to detect and to locate the defects in composite plate by monitoring signals from sensors and using the proposed method.

• Journal of the Korean Society of Safety
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• 제20권1호
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• pp.75-80
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• 2005

In this paper, when CF/EPOXY laminates for high efficiency space structure are subjected to FOD(Foreign Object Damage), the effects of temperature change on the impact damages(inter laminar separation and transverse crack) of CF/EPOXY laminates and the relationship between residual life and impact damages ale experimentally investigated. Composite laminates used in this experiment are CF/EPOXY orthotropic laminated plates, which have two-interfaces $[0^{\circ}_6/90^{\circ}_6]S$ and four-interfaces $[0^{\circ}_3/90^{\circ}_6/0^{\circ}_3]S$. CF/EPOXY specimens with impact damages caused by a steel ball launched from the air gun were observed by the scanning acoustic microscope under room and high temperatures. In this experimental results, various relations were experimentally observed including the delamination area vs. temperature change, the bending strength vs. impact energy and the residual bending strength vs. impact damage of CF/EPOXY laminates. And as the temperature of CF/PEEK laminates increases, the delaminaion areas of impact-induced damages decrease linearly. A linear relationship between the impact energy and the delamination areas were observed. As the temperature of CF/PEEK laminates increases, the delamination areas decrease because of higher initial delaminatin damage energy.

• Journal of the Korean Vacuum Society
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• 제8권2호
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• pp.157-164
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• 1999

The post ion implantation has been applied to modify early-grown BN layer and improve the adhesion of the BN films. The effect of ion implantation doses on microstructure and interlayer was investigated by FTIR and HRTEM. And the hardness and delamination life time of N+-implanted BN films were measured. With increasing the ion dose up to $5.0\times10^{15}\textrm{atoms/cm}^2$,the change of IR spectrum is observed. At $5.0\times10^{16}\textrm{atoms/cm}^2$, a drastic transition of cubic phase into hexagonal phase is detected. The change of microstructure of early-grown layers by ion implantation is confirmed using HRTEM. Both microhardness and delamination life time of BN films increase with ion dose. The modification model of early-grown BN layers is briefly discussed based on the displacement per atom and excess boron in the BN film induced by ion irradiation.

• Proceedings of the KSME Conference
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1271-1276
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• 2008

This study has explained about LED for BLU which is widely used in the kinds of display devices or lighting. It was shown that the open due to delamination were the dominant LED for BLU failure mode and mechanisms from failure analysis of LED samples. Then, we have defined failure as yellowing and 100% reduction of light output intensity of LED for BLU and acceleration factors as temperature and current in Accelerated Life Test(ALT). Finally, we have estimated the Weibull distribution, life-stress relationship, and accelerating factor is used by ALTA Software.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제39권3호
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• pp.30-35
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• 2007

Folding performance is very important in box manufacturing process using paperboard. To evaluate the folding performance of various paperboards, we measured the folding moment and folding behavior at the different folding angle and rate conditions. When linerboard with grammage of $300\;g/m^2$ was folded up to $90^{\circ}$, the compression break and delamination of sheet were observed. The maximum folding moment was little affected by folding angle, but it was increased logarithmically with folding rate. And the effect of paperboard thickness was significant. The maximum folding moment of MD sample was higher than one of CD sample by 40%.