• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.629-640
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• 2008

South anchorage(AN1, Myodo side) of supension bridge between Myodo and Gwangyang is designed as rock anchorage with 36m anchor length using the resistance of rock mass in Myodo. Checking the overall stability of the anchorage, we considered rock joints, bedding planes, fault zones and condition of rock structure in situ by analysis results for photo-lineaments, aerial photograph interpretation and drill-hole logs are considered. This anchorage consists of an access shaft, adit, and the upper and lower concrete bearing plate to introduce pre-stressing force into rock mass.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.115-118
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• 2000

The development of high-strength fibers such as boron/epoxy and carbon/epoxy and adhesives has made it possible to repair cracked metallic plates by bonding reinforcing patches to the plate over the crack. In this study, aluminum 6061-T6 alloy plates with the high strength are applied to specimens with a cracked bolt hole to study the effect of diverse patch materials on the fatigue behavior of this structure. Additionally, the observation of the effort of different patch sizes on the specimen was performed. The results shows that the patch repair can improve the static strength by about 17% and the fatigue life by 200% compared with non-repaired case. And it was also revealed that the patching method along to crack growth direction is mort efficient in cost and weight reduction.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.165-169
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• 1996

In this study residual stress in weldment was considered about the effect on the fatigue propagation and about the effect of redistribution of residual stress. Then, fatigue tests were conducted by the center notched specimens machined with welded plate. The residual stress and its redistribution after the crack growth were measured by the magnetizing stress indicator and hole-drilling method. Fatigue crack propagation was estimated by the specimens having residual stress redistributed after the cracks growth and having the effects of crack closure. Crack growth rates were predicted and compared with experimental results. It had been found that the predicted crack propagation rates have a good agreement with experimental results when the redistribution of residual stress was considerd.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.827-831
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• 1995

This study was designed to etermine the changes in the degree of conversion for composite resins after heat curing following the methods proposed by Lee & Park(1995). 8-mm diameter hole was made in 1mm teflon plate and one of three types of composites (Charisma, Brilllant, Z100) was placed and light cured for 60seconds. The samples were devided into 3 groups according to the placing composites. After light curing, the samples were separated from the moulds. Using this method, 10 samples were prepared in each group; 5 samples from each group were heat cured according to the methods proposed by manutfactures, These samples were then thinned to 50-$70{\mu}m$ and analysed with a Fourier Transform Infrared Spectrometer. Standard baseline technique was used to calculate the degree of conversion. When the samples were light cured, the degrees of conversion in each groups were 47.1 % (charisma), 53.3% (Z100), and 70.1 % (Brilliant). The degree of conversion after heat curing were; 60.1 % (Charisma), 71.1 % (Z100), and 73.3 % (Brillant). Once the samples were heat cured, there were significant increases in degree of conversion.

• Journal of Welding and Joining
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• v.18 no.2
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• pp.184-184
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• 2000

In this study, the lap welding between austenitic stainless steel and carbon steel was carried out using arc spot welding process and weldability of welded specimens was estimated. From the tensile-shear strength test, micro Vickers hardness test, and microstructure observation, specimen of 6.5mm(hole of upper plate) showed the best results in terms of tensile-shear strength and nugget shape. And there was an unmixed zone in fusion boundary between the carbon steel base metal and bulk weld metal. This zone had very thin width with the hard microstructure. The shape of weld nugget in arc spot welding of dissimilar metal welds was predicted by searching thermal history of a weld joint through a three-dimensional finite element model. From the numerical analysis, predicted the shape of weld nugget showed good agreement with the experiment(Received August 24, 1999)

• Journal of Welding and Joining
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• v.18 no.2
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• pp.57-63
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• 2000

In this study, the lap welding between austenitic stainless steel and carbon steel was carried out using arc spot welding process and weldability of welded specimens was estimated. From the tensile-shear strength test, micro Vickers harness test, and microstructure observation, specimen of $psi6.5mm$(hole of upper plate) showed the best results in terms of tensile-shear strength and nugget shape. And there was an unmix zone in fusion boundary between the carbon steel base metal and bulk weld metal. This zone had very width with the hard microstructure. The shape of weld nugget in arc spot welding of dissimilar metal melds was predicted by searching thermal history of a weld joint through a three-dimensional finite element model. From the numerical analysis, predicted the shape of weld nugget showed good agreement with the experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.883-889
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• 2014

Mufflers have been widely used in the exhaust system to reduce the noise. However, installing muffler may deteriorate the efficiency due to the increase of back pressure. Mufflers usually consist of partition plates and perforated holes in a expansion chamber. In this paper, the influences of the location of the partition and hole on the acoustic TL and back pressure were examined. The acoustic TL was predicted using virtual lab commercial software, while the back pressure were predicted using CFX commercial software. The results were used to set up a database for finding their trends. The optimal muffler model in user-interested frequency range could be selected by analyzing this database.

• Journal of the Korean Society of Mechanical Technology
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• v.20 no.6
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• pp.824-829
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• 2018

Molding is the root industry of the manufacturing as a means to mass-produce developed prototypes. Molds are typically divided into injection molds and press mold industries. Injection molds produce the products by injection of molten plastic into a mold, and press molds are molded and bended plate. The ejection system, such as eject pins, is used to separate the manufactured products from the mold, which involves a number of hole operations. Location, diameter and depth of holes are often tabulated and managed collectively when designing 2D drawings. The design efficiency was realized by applying CATIA Automation to the 3D model and bringing in the data of the holes in the Excel data.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.77-82
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• 2017

Objectives: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. Materials and Methods: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. Results: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance ($162.72{\pm}42.55N$), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. Conclusion: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

• Journal of Korean Society of Steel Construction
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• v.27 no.6
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• pp.513-523
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• 2015

In steel moment frames constructed of H-shapes, strong-axis moment connections should be used for maximum structural efficiency if possible. And most of cyclic seismic testing, domestic and international, has been conducted for strong-axis moment connections and cyclic test data for weak-axis connections is quite limited. However, when perpendicular moment frames meet, weak-axis moment connections are also needed at the intersecting locations. Especially, both strong- and weak-axis moment connections have been frequently used in domestic practice. In this study, cyclic seismic performance of RBS (reduced beam section) weak-axis welded moment connections was experimentally investigated. Test specimens, designed according to the procedure proposed by Gilton and Uang (2002), performed well and developed an excellent plastic rotation capacity of 0.03 rad or higher, although a simplified sizing procedure for attaching the beam web to the shear plate in the form of C-shaped fillet weld was used. The test results of this study showed that the sharp corner of C-shaped fillet weld tends to be the origin of crack propagation due to stress concentration there and needs to be trimmed for the better weld shape. Different from strong-axis moment connections, due to the presence of weld access hole, a kind of CJP butt joint is formed between the beam flange and the horizontal continuity plate in weak-axis moment connections. When weld access hole is large, this butt joint can experience cyclic local buckling and subsequent low cycle fatigue fracture as observed in this testing program. Thus the size of web access hole at the butt joint should be minimized if possible. The recommended seismic detailing such as stickout, trimming, and thicker continuity plate for construction tolerance should be followed for design and fabrication of weak-axis welded moment connections.