• Journal of the Korean Geosynthetics Society
• /
• v.6 no.3
• /
• pp.31-37
• /
• 2007

A steel strip reinforcement for the reinforced earth structures was recently developed to substitute the existing ribbed steel strip reinforcement. The developed reinforcement consists of the punched steel strip having dimension of 65mm width and 4.5mm thickness and the transverse steel bar for increasing bearing resistance. The punched steel strip has holes of 11mm diameter in every 50cm spacing with 2mm rising around perimeter of the holes. A series of shear friction tests and pull-out tests were carried out to evaluate the friction properties of the developed reinforcement. The results of these tests show that pull-out resistance of the developed reinforcement was significantly increased when the transverse steel bars are installed in the punched steel strip.

• Journal of Korean Society of Steel Construction
• /
• v.26 no.6
• /
• pp.617-626
• /
• 2014

In this paper, experiments for the evaluation of tensile strength of steel plate with bolt hole and bearing strength of bolted connection were performed, where bolt holes were punched by drilling and oxygen torch, respectively. For the tensile tests, drilled and oxygen torch punched steel plate specimens of 10mm and 15mm thickness were made from structural angles and H-shapes, respectively. For the bearing strength evaluation, test specimens were fabricated with base plates and splice plates those were also punched by drilling and oxygen torch, respectively. The Vicker's hardness were measured around the bolt hole to investigate material property change due to heat effect by oxygen torch cut. Numerical analysis was also performed to investigate the bearing strength of bolted joints due to the increase of hardness around the bolt hole by oxygen torch cut.

• Korean Journal of Veterinary Service
• /
• v.42 no.4
• /
• pp.183-191
• /
• 2019

Claw lesion is one of the major causes of lameness in sows and the lameness is one of the reasons for culling of sows from the swine herd. This survey was conducted on sows in total of 8 farms with a total of 684 pigs. The lesions observed in the study were horizontal and vertical claw cracks (CWH & CWV), differences in the length of toes (T) and/or in the length of dew claws (DC) according to crates, breeds and parity of sows. Scores of claw lesions were assigned on 0, 1, 2, and 3 at each foot depending on the severity of the claw lesions. The sows' parity was classified into 1 to 2, 3 to 4, 5 to 8. Prevalence rate of claw lesions in sows raised on punched plastic crate was higher than that in sows raised on tribar crate. In prevlence rate by breeds, inbreed Landrace sows showed higher than that of Yorkshire sows. According to 4 claw lesions, the length of DC was the highest at parity 3~4 and CWV was the lowest at parity 3~4 in F1 crossbred sows raised on punched plastic crates, respectively. In Yorkshire breeds raised on punched plastic crates, the length of DC at parity 5~8 was the lowest and CWH was the highest at parity 3~4, respectively. In Landrace breeds raised on tribar crates, CWH was the highest at parity 1~2 and CWV was the lowest at parity 3~4, respectively. The high parity in F1 crossbred sows showed high prevalence rate of claw lesions than that of low parity and other inbreed sows, respectively. These results may be useful as elementary data in establishment of welfare quality protocol and preventive measures to reduce economic losses from craw lesions in sows.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.34 no.2
• /
• pp.91-99
• /
• 2012

Purpose: The purpose of this study was to evaluate the expression of osteogenic genes associated with bone regeneration on anodizing titanium surface. Methods: $20{\times}20{\times}1$ (mm) commercially pure titanium plate was made, one group was pure titanium, second group was punched, and last group was punched and anodized by electrochemical method. Through the osteogenic cell culture model, the expression of extracellular matrix proteins, such as bone morphogenetic protein-2, bone sialoprotein, aggrecan, osteocalcin, Alkaline phosphatase, collagen I had been evaluated by Real-time polymerase chain reaction, and the morphology of growing cells was evaluated by scanning electron microscopy. Results: The attachment of mesenchymal stem cell was even and well-oriented on all Ti surfaces. The osteogene expression was increased on punching groups but, decreased on anodizing surfaces in 3 week samples. Conclusion: Punched anodizing Ti has possibility be using as a dental implant material, but further in vivo study would be needed.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.4
• /
• pp.519-528
• /
• 2008

A simple steel-concrete composite deck is developed for preventing the lateral torsional buckling of girders that are under construction and for reducing the term of works using H-shaped rolled beams as bridge girders. A new type of shear connectors is also developed for the composite behavior between a simple steel-concrete composite deck and the rolled beams by the connecting conditions between the deck and the girders. One is a connector bolt that is lengthened and split or tightened with two nuts and the other is an I-shaped rolled beam welded on a steel plate with a number of holes punched through the web. In this study, to estimate the shear strength of those shear connectors the push-out tests are performed and the test results are compared with that of the previous studies and the codes. The result of the push-out tests of the connector bolts showed that the shear performance is similar to that of the stud connector and revealed that the equation for the shear strength in the Korean Specification of Highway Bridge overestimates the shear capacity of the connector bolt whose diameter is larger than 19mm. From the push-out tests of punched I-shaped rolled beams with varying welding amounts, with the small amount of welding, shear capacity is governed by the shear capacity of welding. On the other hand, shear capacity is governed by the size of the punched I-shaped rolled beams, regardless of the amount of welding.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.34 no.1
• /
• pp.51-58
• /
• 2021

In this paper, a multi-scale finite element (FE) modeling methodology for three-dimensional (3D) needle-punched (NP) C/SiC with a complex microstructure is presented. The variations of the material properties induced by the needle-punching process and complex geometrical features could pose challenges when estimating the material behavior. For considering these features of composites, a 3D microscopic FE approach is introduced based on micro-CT technology to produce a 3D high fidelity FE model. The image processing techniques of micro-CT are utilized to generate discrete-gray images and reconstruct the high fidelity model. Furthermore, a subcell modeling technique is developed for the 3D NP C/SiC based on the high fidelity FE model to expand to the macro-scale structural problem. A numerical homogenization approach under periodic boundary conditions (PBCs) is employed to estimate the equivalent behavior of the high fidelity model and effective properties of subcell components, considering geometry continuity effects. For verification, proposed models compare excellently with experimental results for the mechanical behavior of tensile, shear, and bending under static loading conditions.

• Proceedings of the Korean Fiber Society Conference
• /
• 1994.10a
• /
• pp.38-39
• /
• 1994

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.1
• /
• pp.44-53
• /
• 2006

In this study, the non-destructive computed tomography was adopted to observe the density profile of the needle-punched Carbon/Carbon(C/C) composites nozzle throat. The density profile of C/C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.11a
• /
• pp.260-265
• /
• 2004

LTCC(Low temperature co-fired ceramic) is being recognized as a significant packaging material of electrical devices for the advantages such as relatively low temperature being needed for process, low conductor resistance and high printing resolution. In the process of LTCC electrical devices, the punched via-hole quality is one of the most important factors on the performance of the device. However, its mechanism is very complicated and optimization of the process seems difficult. In this paper, to clarify the process, via-hole punching experiments were carried out and the punched holes were examined in terms of their burr formation. The effects of thickness of PET sheet and ceramic sheet and punch-to-die clearance on via-hole quality were also discussed. Optimum process conditions are proposed and a factor k is introduced to express effect of the process variables.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.sup1
• /
• pp.124-127
• /
• 2001

Langerhans' cell histiocytosis is a rare disease showing proliferation of histiocytes in multiple organ system. Bone lesions are the most common radiolologic manifestation of Langerhans' cell hysticytosis. Extraskeletal sites of Langerhans' cell hystiocytosis involvement include the skin, lymph nodes, thymus, lungs, central nervous system, liver, pancrease, spleen, and bowel. The authors have experienced a case of Langerhans' cell histiocytosis which involved the skull. A 3-year-old female presented with soft tissue mass on right periorbital area. Plain skull X-ray showed punched out bone lesion. Computed tomography showed non-enhancing osteolytic lesion on right frontal skull. Histologic findings of an excised mass revealed pathologic features of Langerhans' cell histiocytosis.