• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.405-410
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• 2020

Purpose: Pedicle screw insertion has been traditionally used as a surgical treatment for degenerative lumbar spine disease. As an alternative, the cortical-bone trajectory screw allows less invasive posterior lumbar fixation and excellent mechanical stability, as reported in several biomechanical studies. This study evaluated the clinical and radiological results of a case of early failure of cortical-bone screw fixation in posterior fixation and union after posterior decompression. Materials and Methods: This study examined 311 patients who underwent surgical treatment from 2013 to 2018 using cortical orbital screws as an alternative to traditional pedicle screw fixation for degenerative spinal stenosis and anterior spine dislocation of the lumbar spine. Early fixation failure after surgery was defined as fixation failure, such as loosening, pull-out, and breakage of the screw on computed tomography (CT) and radiographs at a follow-up of six months. Results: Early fixation failure occurred in 46 out of 311 cases (14.8%), screw loosening in 46 cases (14.8%), pull-out in 12 cases (3.9%), and breakage in four cases (1.3%). An analysis of the site where the fixation failure occurred revealed the following, L1 in seven cases (15.2%), L2 in three cases (6.5%), L3 in four cases (8.7%), L4 in four cases (8.7%), L5 in four cases (8.7%), and S1 in 24 cases (52.2%). Among the distal cortical bone screws, fixation failures such as loosening, pull-out, and breakage occurred mainly in the S1 screws. Conclusion: Cortical-bone trajectory screw fixation may be an alternative with comparable clinical outcomes or fewer complications compared to conventional pedicle screw fixation. On the other hand, in case with osteoporosis and no anterior support structure particularly at L5-S1 fusion sites were observed to have result of premature fixation failures such as relaxation, pull-out, and breakage.

• International Journal of Concrete Structures and Materials
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• v.18 no.1E
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• pp.29-34
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• 2006

Elastic modulus, tensile and bond capacities are important factors for developing an effective reinforcing action of a flexural member as a reinforcing material for concrete structures. Reinforcement must have enough bond capacity to prevent the relative slip between concrete and reinforcement. This paper presents an experimental study to clarify the bond capacity of prestressed carbon fiber reinforced polymer(CFRP) rod manufactured by an automatic assembly robot. The bond characteristics of CFRP rods with different pitch of helical wrapping were analyzed experimentally. As the result, all types of CFRP rods show a high initial stiffness and good ductility. The mechanical properties of helical wrapping of the CFRP rods have an important effect on the bond of these rods to concrete after the bond stress reached the yield point. The stress-slip relationship analyzed from the pull-out test of embedded cables within concrete was linear up to maximum bond capacity. The deformation within the range of maximum force seems very low and was reached after approximately 1 mm. The average bond capacity of CF20, CF30 and CF40 was about 12.06 MPa, 12.68 MPa and 12.30 MPa, respectively. It was found that helical wrapping was sufficient to yield bond strengths comparable to that of steel bars.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.314-319
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• 2004

Many of researches regarding mechanical properties of composite materials are associated with humid environment and temperature. Especially the temperature is a very important factor influencing the design of thermoplastic composites. However, the effect of temperature on impact behavior of reinforced composites have not yet been fully explored. An approach which predicts critical fracture toughness GIC was performed by the impact test in this work The main goal of this work is to study effects of temperature in the impact test with glass fiber/polypropylene(GF/pp) composites. The critical fracture energy and failure mechanisms of GF/PP composites are investigated in the temperature range of $60^{\circ}C\;to\;-50^{\circ}C$ by impact test. The critical fracture energy shows a maximum at ambient temperature and it tends to decrease as temperature goes up or goes down. Major failure mechanisms can be classified such as fiber matrix debonding, fiber pull-out and/or delamination and matrix deformation.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3027-3031
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• 2011

In this study, By the time that TTX technology is adopted as railway rolling stock, we analyzed quantitatively energy saving by reducing the power consumption with the reduction of the operation time through the speed improvement and suggested the necessity to introduce TTX technology in the domestic rail vehicles. The effect of energy saving by comparing and analyzing the power consumption during the operation by TTX Hanvit 200 and 8200 electric locomotives to pull trains on the same line was suggested and the efficiency of the main devices(i.e C/I) of Hanvit 200 was compared and analyzed by measuring the power consumption by a single unit. For improving KORAIL management environment, reducing energy usage is an urgent challenge, its measures for solving them are constantly considered in many areas. In addition, at the time of improving the conventional track to speed up and changing the signals, Tilting technology will be contributed to the management environment by enlarging the passengers' demand through the reduction of the operation time and saving energy using the existing infrastructure.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.4
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• pp.71-77
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• 2003

Security system in internet as well as the performance in information network became more important as the internet environment is getting popular and complicate. In this study, the security system (Firewall and IDS) was installed in high speed information network and analyzed for a change in the speed of data transfer and the possibility of invasion. The selection of appropriate system, efficient detection and protection and surveillance method were suggested and analyzed In order to do experiments, an experimental model was com prized to analyze the parameters that was affected by the detection and protection system in network. This will give a standard how much we can pull up the security system maintaining the network speed.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.610-612
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• 2008

Piston cores retrieved from the eastern part of the deep-water Ulleung Basin were analyzed to access the potential of hydrocarbon gas generation and natural gas hydrate (NGH) formation. Seismic data acquired in the study area were also analyzed to determine the presence of hydrocarbon gas and/or NGH, and to map their distribution. Core analyses revealed high total organic carbon (TOC) contents which favor hydrocarbon generation. The cores recovered from the southern study area showed the sufficient residual hydrocarbon gas concentrations for the formation of significant NGH. These cores also showed the cracks developed parallel to the bedding that suggest significant gas content in situ. A number of seismic blanking zones were observed on seismic data. They are identified as vertical to sub-vertical chimneys caused by the upward migration of pore fluid or gas, and containing of free gas and/or NGH. Often, they are associated with velocity pull-up structures that are interpreted to be the result of high-velocity NGH. The seismic data also showed several bottom-simulating reflectors (BSRs) that are associated with overlying NGH and underlying free gas. The distribution of blanking zones and BSRs would be impacted by the lateral differences of upward methane fluxes.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.507-510
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• 2007

Piston cores retrieved from the western Ulleung Basin, East Sea were analyzed to examine the potential for hydrocarbon generation and to determine the hydrocarbon indicators. 2D multi-channel reflection seismic and Chirp data were also investigated for mapping and characterizing the geophysical hydrocarbon indicators such as BSR (bottom simulating reflector), blank zone, pock-mark etc. High organic carbon contents and sedimentation rates that suggest good condition for hydrocarbon generation. High pressure and low temperature condition, and high residual hydrocarbon concentrations are favor the formation of natural gas hydrate. In the piston cores, cracks generally oriented to bedding may indicate the gas expansion. The seismic data show several BSRs that are associated with natural gas hydrates and underlying free gas. A number of vertical to sub-vertical blank zones were well identified in the seismic sections. They often show the seismic pull-up structures, probably indicating the presence of high velocity hydrates. Numerous pockmarks were also observed in the Chirp profiles. They may indicate the presence of free gas below the hydrate stability zone as well.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.74-76
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• 2010

Digital images or videos are used in modern digital devices. The resolution of HDTV in digital broadcasting system is higher than that of previous analog systems. Also, mobile phone with 3G can provide images as well as video streaming services in realtime. In these circumstances, the visual quality of images has become an important factor. We can make image clear by transient improvement process that reduces transient in edges. In this paper, we present an transient improvement algorithm. The proposed algorithm improves edges by making smooth edge to steep edge. Before performing transient improvement algorithm, edge detection algorithm should be operated. Laplacian operator is used in edge detection, and the absolute value of it is used to calculate gain value. Then, local maximum and minimum values are computed to discriminate current pixel value to raise up or pull down. Compensating value that gain value multiplies with the difference between maximum (or minimum) value and current pixel value adds (or subtracts) to current pixel value. That is, improved signal is generated by making the narrow transient of edge. The advantage of proposed algorithm is that it doesn't produce shooting problem like overshoot or undershoot.

• Journal of Chest Surgery
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• v.7 no.2
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• pp.201-208
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• 1974

The purpose of this paper is to present author's experience with 6 cases of ruptured aneurysm of sinus of Valsalva which were treated surgically during last 10 years. Among the 6 cases, 5 were male and one was female. All of them originated from the right coronary sinus and 5 cases were ruptured into the RV while remained one into RA. The diagnosis was obtained in 4 cases by cineangiocardiogram. Clinically, we had difficulties in differential diagnosis with combined cases of VSD with A.I. and had special experience in its differentiation during cardiac catheterization. By simultaneous trans-venous and trans-arterial catheterization, identified two catheter tips in the RV, and pull back tracing obtained aortic pressure directly from RV, and RA from RV pressure which were benefit in confirm ruptured aneurysm of the aortic sinus. Surgical correction was performed by means of direct suture closure or combined Teflon pledget Of patch enforcement graft after aneurysm resection by trans-RA or trans-RV approach. All patients had no history of bacterial endocarditis, syphilis, or tuberculosis and operative findings revealed intact coronary sinus except involved one moreover 3 cases combined with high VSD which uggested congenital in origin although pathologic reports revealed only fibrosis. Post-operative course were uneventful in all cases but one who had bleeding and 2 months to 9 years follow up results were good and spend their usual life in all cases.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.240-245
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• 2001

The tensile strength and failure mechanisms of glass fiber polypropylene (GF/PP) composites are investigated in the temperature range from ambient to 8$0^{\circ}C$. The tensile strength increases as fiber volume fraction ratio increase. The tensile strength shows a maximum at ambient temperature, and it tens to decrease as temperature goes up. Major failure mechanisms of GF/PP composites can be classified as fiber matrix debonding, fiber pull-out, delamination and matrix deformation.