• Design & Manufacturing
• /
• v.10 no.3
• /
• pp.1-7
• /
• 2016

In the semiconductor industry the memory and chip were developed to high density memory and high performance chip, so circuit design was also high integrated and the test bed was needed to be thin and fine pitch socket. LGA(Land Grid Array) IC socket with thin wall thickness was designed to satisfy this requirement. The LGA IC socket plastic part was manufacture by injection molding process, it was needed accuracy, stiffness and suit resin with high flowability. After injection molding process the side gates were needed to remove for further assembly process. ln this study, the cold press cutting process was applied to remove the gates. For design of punch and die, the cold press cutting analysis was implemented by$DEFORM-2D^{TM}$ ln consideration of the simulation results, an adequate punch and die was designed and made for the cutting unit. In order to verify the performance of cutting process, the roughness of cutting section of the part was measured and was satisfied in requirement.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.10
• /
• pp.25-32
• /
• 2008

Based on recent studies, the side resistance of rock socketed drilled shafts was affected by unconfined compressive strength of rock, socket roughness, rock types and joints, and initial normal stress. Especially, the socket roughness was affected by rock types and joints, drilling methods, and diameters of pile. In this study, a new roughness measurement system (BKS-LRPS, Backyoung-KyungSung Laser Roughness Profiling System) usable in water was developed. Based on the laboratory model tests, an EMD (Effective Measurement Distances) according to various turbidity was proposed as $EMD=1149.2{\times}T_{b}^{-0.64}$.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.03a
• /
• pp.147-152
• /
• 2003

The purpose of this paper is to develope an understanding of fundamental mechanism of shear behaviour between granite and concrete interfaces. The interface of pile socketed in rock can be modeled in laboratory tests by resolving the axisymmetric pile situation into the two dimensional situation under CNS(constant normal stiffness) direct shear condition. In this paper, the granite core samples were used to simulate the interface condition of piles socketed In granite. The samples were prepared in the laboratory to simulate field condition, roughness(angle, height), stress boundary condition, and then tested by CNS direct shear tests. This paper gives some points about shearing behaviour of socket piles into domestic granite through the analysis of CNS tests results.

• Journal of the Korean GEO-environmental Society
• /
• v.4 no.2
• /
• pp.5-13
• /
• 2003

The domestic design method for the shaft resistance of drilled shafts into a bedrock is based on the empirical method, where the uniaxial compressive strength of rock specimen is utilized for calculation of the shaft resistance. This method has uncertainties in prediction of capacity of drilled shafts and result in uneconomic engineering design. Recently a new improved design method was suggested, which reflects important factors that affect the strength of pile sockets. Socket roughness is one of the significant factors influencing the shaft resistance of drilled shaft socketed into rock. In this paper roughness information for the shaft resistance design of socket pile was suggested on the basis of statistical analysis of data measured from wall surface in the bore holes of drilled shafts.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.5
• /
• pp.281-293
• /
• 2002

Empiricism has characterized the traditional methods of pile design; in essence, pile design recommendations are based on the accumulated knowledge of pile behaviour based on the construction and subsequent load testing of piles in soil and rock. In this paper, the traditional approaches to design of piles in rock will be briefly reviewed. It will be shown that the unrelated empirical relationships developed fur rock lead to considerable uncertainty in the design of piles. A new method for predicting the shaft resistance of piles socketed into rock, and based on fundamental principles is outlined. It is shown that the shaft resistance predictions of this method agree well with the field test data for rock and hard soil. It is demonstrated by way of a limited parametric study that shaft roughness and socket diameter are critical factors in the performance of piles constructed in these materials. The application of the method to piles socketed into the granites and gneisses of Korea is discussed by way of a case study and by reference to recent direct shear tests on these rocks.

• Design & Manufacturing
• /
• v.10 no.2
• /
• pp.50-54
• /
• 2016

In the semiconductor industry the final products were checked for several environments before sell the products. The burning test of memory and chip was implemented in reliability for all of parts. The memory and chip were developed to high density memory and high performance chip, so circuit design was also high integrated and the test bed was needed to be thin and fine pitch socket. LGA(Land Grid Array) IC socket with thin wall thickness was designed to satisfy this requirement. The LGA IC socket plastic part was manufacture by injection molding process, it was needed accuracy, stiffness and suit resin with high flowability. In this study, injection molding process analysis was executed for 2 and 4 cavities moldings with runner, gate and sprue. The warpage analysis was also implemented for further gate removal process. Through the analyses the total deformations of the moldings were predicted within maximum 0.05mm deformation. Finally in consideration of these results, 2 and 4 cavities molds were designed and made and tested in injection molding process.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.967-973
• /
• 2004

Rock socketed drilled shafts transfer significant portion of structural loads at the socketed part. Therefore, a proper design of side and base resistances of a shaft at the socket is a major concern for the geotechnical engineers. In this study, we modified the Hoek-Brown criterion to estimate side resistance of rock socketed drilled shafts. Earlier method to compute side resistance of a shaft is linear or power functions of intact rock masses. However, side resistance is mobilized like shearing which influenced by the mechanical properties of concrete and rock masses, adhesion of rock/concrete interface, roughness of rock socket. Therefore, a single coefficient or power of uniaxial compressive strength of intact rock cannot provide accurate values of side resistance in a wide range of the uniaxial compressive strength. A new approach proposed in this study can consider in situ rock mass condition (frequency or discontinuities, weathering condition), and rock types thus, it has a wider applicability than the earlier models.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.1
• /
• pp.5-12
• /
• 2004

The purpose of this paper is to make an understanding of fundamental mechanism of shear behaviour between rock and concrete interfaces in the pile socketed into granite. The interface of pile socketed in rock can be modeled in laboratory tests by resolving the axi-symmetric pile situation into the two dimensional situation under CNS(constant normal stiffness) direct shear condition. In this paper, the granite core samples were used to simulate the interface condition of piles socketed in granite in our country. The samples were prepared in the laboratory to simulate field condition, roughness(angle and height), stress boundary condition, and then tested by CNS direct shear tests. This paper describes shearing behaviour of socket piles into domestic granite through the analysis of CNS test results. It was found out that the peak shear strength increases with the angle of asperity and CNS value, and also the dilation increases with the angle of asperity but decreases with the CNS value.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.4
• /
• pp.5-13
• /
• 2008

Just as infill material can reduce the shear strength of a rock joint, a layer of soft material between concrete and the surrounding rock socket can reduce pile shaft resistance of drilled shafts socketed in rocks. This can also result from construction methods that leave smeared or remoulded rock or drilling fluid residue on the sides of the rock sockets after concrete placement. The nature of the interface between the concrete pile shaft and the surrounding rock is critically important to the performance of the pile, and is heavily influenced by construction practice. Characteristics of the concrete-rock interface, such as roughness and the presence of the soft materials deposited during or after construction can significantly affect the shaft resistance response of the pile. In this study, we conducted the parametric study to examine the performance characteristics of drilled shafts socketed in smeared rock under the vertical load with the code of finite difference method of FLAC 2D. As the results of the current research, the parameters that affect the settlement of the pile head and the ultimate unit shaft resistance could be identified.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.7
• /
• pp.23-35
• /
• 2006

Shear load transfer characteristics of rock-socketed drilled shafts were analyzed. The constant normal stiffness (CNS) direct shear tests were performed to identify the major influencing factors of shaft resistance, i.e., unconfined compressive strength, borehole roughness, normal stiffness, initial confining stress, and material properties. Based on the CNS tests, shear load transfer function of drilled shafts in rocks is proposed using borehole roughness and the geological strength index (GSI), which indicates discontinuity and surface condition of rock mass in Hoek-Brown criterion (1997). The proposed load-transfer function was verified by the load test results of seven rock-socketed drilled test shafts subjected to axial loads. Through comparisons of the results of load tests, it is found that the load-transfer function by the present study is in good agreement with the general trend observed by in situ measurements, and thus represents a significant improvement in the prediction of load transfer of drilled shafts.