• Journal of the Korean Geotechnical Society
• /
• v.15 no.4
• /
• pp.207-220
• /
• 1999

Model tests were performed to investigate the failure modes in embankments on soft ground supported by piles with cap beams. In the model tests, Jumunjin standard sand was placed on simulated cap beams and soft ground. The cap beams are placed perpendicular to the longitudinal axis of the embankment. The colored sand and the Jmniin standard sand were placed one after the other above cap beams and soft ground to make lateral stripes with 3mm thickness in the embarkment. The colored sand was prepared by coating the Jumunjin sand with black lead powder. The photographs illustrate the two characteristic modes of failure in embarkments. One is the soil arching failure and the other is the punching shear failure. The failure mode depends on the height of embankment and the space between cap beams. That is, if the embankment is high enough compared with the space between cap beams, it will fail in arching failure. On the other hand if the embarkment is relatively low or the space between piles is too wide, it will fail in punching shear failure. The soil arching develops in embarkment as a semicylindrical arch with a thickness equal to the width of the cap beam. And the soil wedge developed above the cap beams remains intact during both arching and punching failures. The boundary of punching shear failure of the displaced soil mass can be defined on the basis of observation of the photographs.

• Journal of Welding and Joining
• /
• v.9 no.4
• /
• pp.60-68
• /
• 1991

The weld quality of end cap welds in Pressurized Heavy Water Reactor (PHWR) Fuel is extremely important for the fuel performance in the nuclear reactor. The quality of resistance upset welds is currently evaluated mainly by the metallographic examination although it reveals only two weld cross-sections in a circumference welds. This investigation was, firstly, carried out to determine whether the ultrasonic examination would be applied to detect weld defects in the end cap welds and, secondly, to measure the mechanical strength of upset butt welds as a function of phase shift percentage. The major results obtained in this study are as follows: 1. The weld current and amount of upset shrinkage linearly increased with increasing the phase shift percentage. 2. Above the phase shift 55%, the defects in the welds were completely eliminated with increasing the phase of sound weld was over the thickness of cladding tube. 3. The ultrasonic testing well detected such defects in the end cap welds as upset external crack, upset split, corner crack and irregular weld flash comparing with the results of metallography. 4. The micro-fissure in the corner of the end cap welds was reliably detected by ultrasonic testing. 5. The mechanical strength in the welds increased with increasing phase shift percentage but the fracture did't occur in the welds above 55%.

• Journal of the Korean Society of Visualization
• /
• v.14 no.2
• /
• pp.25-30
• /
• 2016

The wafer temperature and its uniformity inside the LPCVD chamber were analyzed. The temperature uniformity at the end of the wafer load depends on the heat-insulating cap. The finite difference method was used to investigate the radiation and conduction heat transfer mechanisms, and the temperature field and heat diffusion in the LPCVD chamber was visualized. It was found that the temperature uniformity of the wafers could be controlled by the size and distance of the heat-insulating cap.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.113-114
• /
• 2007

Hole mobility characteristics of single surface channel and dual channel Si/SiGe structure are compared, where the former one consists of a relaxed SiGe buffer layer and a tensile strained Si layer on top, and for dual channel structure a compressively strained SiGe layer is inserted between them. Due to the difference of hole mobility enhancement factors of layers between them, hole mobility characteristics with respect to the Si cap thickness shows the opposite tend. Hole mobility increases with thicker Si cap for single channel structure, whereas it decreases with thicker Si cap for dual channel structure.

• Journal of Wind Energy
• /
• v.5 no.1
• /
• pp.50-55
• /
• 2014

Surface Permanent-Magnetic-Synchronous-Generator (SPMSG) discussed in the present study has operational characteristics such as high rotational speed over 1,000 rpm and centrifugal force of 12 kN·m for each magnet. Structure-development analysis for the minimization of rotor-core weights and the maximization of thermal emission is performed by applying the aluminum-laminated cap which combines the advantages of IPM and SPM in order to overcome the difficulty that attaching the magnet to rotor-core only with an adhesive. In this study, the simulations in terms of structure and electromagnetic were performed with the variable parameters such as shape and thickness of laminated-cap and division method of magnet. As a result, condition for minimized centrifugal force with minimum loss is derived.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.539-542
• /
• 2001

In SiC semiconductor device processing, it needs high temperature anneal for activation of ion implanted dopants. The macrosteps, 7~8nm in height, are formed on the surface of SiC substrates during activation anneal. We have investigated the effect of thermally-grown SiO$_2$layer on the suppression of macrostep formation during high temperature anneal. The cap oxide layer was found to be efficient for suppression of macrostep formation even though the annealing temperature is as high as the melting point of SiO$_2$. The thin cap oxide layer (10nm) was evaporated during anneal then the macrosteps were formed on SiC substrate. On the other hand the thicker cap oxide layer (50nm) remains until the anneal process ends. In that case, the surface was smoother and the macrosteps were rarely formed. The thermally-grown oxide layer is found to be a good material for the suppression of macrostep formation because of its feasibility of growing and processing. Moreover, we can choose a proper oxide thickness considering the evaporate rate of SiO$_2$at the given temperature.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.1
• /
• pp.60-70
• /
• 2022

We evaluated the performance of in-situ capping to prevent the release of phenol, one of hazardous chemicals of concern for their impact on sediment. Sediment near the estuary of Hyeongsan River, Korea, and commercially-available sand were collected to evaluate their physical properties and phenol sorption characteristics. Biodegradation kinetics of phenol spiked into the sediment was evaluated under freshwater and estuarine salinity conditions. These experimental measurements were parameterized and used as input parameters for executing CapSim, a software predicting the performance of in-situ capping. The CapSim simulation demonstrated that capping with 50-cm sand reduced the phenol release by several orders of magnitude over 0.25- and 1-year duration for almost all simulation scenarios. The variables tested, i.e., cap thickness, pore-water movement, and biodegradation rate, showed high correlation to each other to influence the extent of phenol release from sediment to the water column. The findings and the framework employed to evaluate the performance of in-situ capping in this study can be adopted to determine whether in-situ capping is appropriate remedial approach at sediment sites impacted by hazardous chemicals due to accidental spills.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.04b
• /
• pp.39-42
• /
• 2000

As gate dimensions continue to shrink below $0.2{\mu}m$, improving CD (Critical Dimension) control has become a major challenge during CMOS process development. Anti-Reflective Coatings are widely used to overcome high substrate reflectivity at Deep UV wavelengths by canceling out these reflections. In this study, we have investigated Batchtype system for PECVO SiOxNy as Anti-Reflective Coatings. The Singletype system was baseline and Batchtype system was new process. The test structure of Singletype is SiON $250{\AA}$ + Cap Oxide $50{\AA}$ and Batchtype is SiON $250{\AA}$ + Cap Oxide $50{\AA}$ or N2O plasma treatment. Inorganic chemical vapor deposition SiOxNy layer has been qualified for bottom ARC on Poly+WSix layer, But, this test was practiced on the actual device structure of TiN/Al-Cu/TiN/Ti stacks. A former day, in Batchtype chamber thin oxide thickness control was difficult. In this test, Batchtype system is consist of six deposition station, and demanded 6th station plasma treatment kits for N2O treatment or Cap Oxide after SiON $250{\AA}$. Good reflectivity can be obtained by Cap Oxide rather than N2O plasma treatment and both system of PECVD SiOxNy ARC have good electrical properties.

• Journal of Welding and Joining
• /
• v.23 no.1
• /
• pp.55-60
• /
• 2005

A three-dimensional Gaussian heat source model is modified to include the effects of the gap and thickness-difference for the laser keyhole welding. The gap of the butt joint influences the welding efficiency such that the melting area decreases linearly with the gap. When the different plate thickness is used such as the tailored blank welding, melting areas of the thick and thin plates are predicted by introducing the thickness-difference factor. The calculated results using the modified heat source show reasonably good agreements with the experimental results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.1
• /
• pp.44-48
• /
• 2008

Hole mobility characteristics of two representative biaxially strained SiGe/Si structures with high Ge contents are studied, They are single channel ($Si/Si_{1-x}Ge_x/Si$ substrate) and dual channel ($Si/Si_{1-y}Ge_y/Si_{1-x}Ge_x/Si$ substrate), where the former consists of a relaxed SiGe buffer layer with 60 % Ge content and a tensile-strained Si layer on top, and for the latter, a compressively strained SiGe layer is inserted between two layers, Owing to the hole mobility performance between a relaxed SiGe film and a compressive-strained SiGe film in the single channel and the dual channel, the hole mobility behaviors of two structures with respect to the Si cap layer thickness shows the opposite trend, Hole mobility increases with thicker Si cap layer for single channel structure, whereas it decreases with thicker Si cap layer for dual channel. This hole mobility characteristics could be easily explained by a simple capacitance model.