• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.4
• /
• pp.366-375
• /
• 2001

The objective of this study was to investigate the surface contact and screw joint stability between screw and implant interface by use of sealer. The implants evaluated in this study were Steri-Oss futures(Hexlock $3.8D{\times}10mm$: Steri-Oss, Yorba Linda, CA), and Steri-Oss staight abutment. Titanium alloy screws were used to secure abutments to implants. The other titanium alloy screws applicating sealer(Impla-Seal, Implant Support Systems, Inc. Irvine, CA) were used to secure abutments to implants. In one another sample, 6kg of force was applied during simulated intraoral movements after abutment screws were secured to the implants with sealer. All samples were cross sectioned with sandpaper and polished with $0.1{\mu}m\;Al_2O_3$. Then samples were recorded with an scanning electron microscope. The results were as follows : 1. In the case of titanium alloy screw, irregular contacts and relatively large gap were present at thread mating surface. Also abutment screw/implant interface demonstrate incomplete seating and only one surface contact of threads between implant and screw. 2. In the case of titanium alloy screw applecating sealer, sealer was present between implant and screw. Therefore implant and screw had relatively close and tight contact without the presence of large gap. 3. On the other hand, in the case of titanium alloy screw applicating sealer and dynamic loading of suprastructures, sealer was partially present between implant and screw. Conclusively, sealer fills voids, creating a barrier to moisture and bacteria. In addition, loading of suprastructures may change the situation and limit the indications for gap sealing.

• International Journal of Korean Welding Society
• /
• v.2 no.1
• /
• pp.45-51
• /
• 2002

In the multi-pass welding of pressure vessels or ships, the mechanical touch sensor system is generally used together with a manipulator to measure the gap and depth of the narrow gap to perform seam tracking. Unfortunately, such mechanical touch sensors may commit measuring errors caused by the deterioration of the measuring device. An automation system of narrow gap multi-pass welding using a laser vision system which can track the seam line of narrow gap and which can control welding power has been developed. The joint profile of the narrow gap, with 250mm depth and 28mm width, can be captured by laser vision camera. The image is then processed for defining tracking positions of the torch during welding. Then, the real-time correction of lateral and vertical position of the torch can be done by the laser vision system. The adaptive control of welding conditions like welding currents and welding speeds, can also be performed by the laser vision system, which cannot be done by conventional mechanical touch systems. The developed automation system will be adopted to reduce the idle time of welders, which happens frequently in conventional long welding processes, and to improve the reliability of the weld quality as well.

• Journal of the Korean Wood Science and Technology
• /
• v.16 no.4
• /
• pp.48-53
• /
• 1988

This study was carried out to investigate the effects of pressing time and spreading amount, moisture content, gap-distance with butt to butt joint and adhesives on bonding strength in manufacturing the laminated wood with Pitch pine (Pinus rigida). The results obtained were as follows: 1) The pressing time of 12 hours, 10 kilogram per square centimeter of pressure and 200 gram per square meter of spreading amount were required to reach over 50 kilogram per square centimeter (block shear strength) in manufacturing the laminated wood by aqueous vinyl urethane adhesive. 2) The bonding strength decreased with the increase of moisture content of wood. The block shear strength, however, showed over 100 kilogram per square centimeter when the strength test was carried out after air-drying the laminated wood in high moisture content (30-70%). 3) Regardless of direction of load, every flexural property decreased with the increase of gap-distance with butt to butt joint. However, little of every flexural property was changed at 0.5 millimeter of joint-gap distance. The flexural property of vertically laminated wood (perpendicular to glue line to load direction: 1) showed more than that of horizontally laminated wood (parallel to glue line to load direction: //). 4) Among five adhesives used at this experiment, the bonding strength of aqueous vinyl urethane adhesive was the highest in dry bond and wet tests.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.4
• /
• pp.1290-1295
• /
• 2014

In this paper, various configurations of octagonal wound transformer core topology, which has previously proved advantages on conventional wound cores, are studied. Each configuration has different joint types and different placement of joint zones on the core. Magnetic flux distributions and power losses of each configuration are analyzed and compared. Comparisons are based on both 2D&3D finite element simulations and experimental studies. The results show that, joint types and their placements on the core cause local flux accumulations and dramatically affect power loss of the core.

• Journal of the Korean Society for Precision Engineering
• /
• v.30 no.8
• /
• pp.815-823
• /
• 2013

The hot curvature forming of large aluminum plates is a process used to produce spherical liquefied natural gas (LNG) tanks. In this study, we describe a method to determine the optimum shape of blanks to minimize the root gap in the forming process. The method proposed in this study was applied to a small-scale model for thick plates with a curvature of 1500 mm and thickness of 6 mm. First, the shape of the curved shells was determined as the target shape, and then a coordinate transform was used to determine the optimum blank shape, which was then iteratively modified using the results of finite element method (FEM) simulations, including heat transfer, until the shape error was minimized. Experiments in forming using Al5083 thick plate were carried out, showing that the method can determine the optimum blank shape within an allowable root gap of 0.1 mm.

• The Journal of the Korean dental association
• /
• v.19 no.4 s.143
• /
• pp.375-380
• /
• 1981

Unilateral bony ankylosis of temporomandibular joint is not extremely rare. Treatment in all cases should be surgical. Considerable difficulty has been encountered by surgeons in the judgment of the planning of the treatment for anklosis; either by gap arthroplasty or by interposition arthroplasty. A recent review of the literautre reveals that many authors reported more of the interposition arthroplasty treatment because of no recurrence and the excellent results obtained. This 22-year-old Korean female, who had suffered from unilateral temporomandibular joint recurrent anklosis, was received an operation of ramus osteotomy followed by interpositional arthroplasty with using of thin gold plate. She formerly was received condylectomy twice at the age of 8 and 9, under the diagnosis of unilateral bony ankylosis due to trauma. My experience with alloplasty in unilaterally recurrent ankylosed T-M joint is presented here for her general and oral functional condition proved to be satisfactory after 4 years follow-up.

• Laser Solutions
• /
• v.12 no.3
• /
• pp.14-17
• /
• 2009

The laser welding was performed for the flange joint of two overlapped coaxial circular pipes which serve as the inlet and connector pipes of STS 316L. The laser welding test finally resulted in a good penetration depth of 1.8 to 2.0 mm. On the way to get the good welding quality, two important parameters were found to be optimized. One is the focal positioning which is the offset of the laser beam focus to the exact welding seam line, which is more critical in the inner flange laser welding. When the beam spot size was deviated more than $200\;{\mu}m$ from the seam line, welding of two pipes is failed. The other is a gap size since a certain amount of gap is inevitable due to fabrication tolerance, or artificial allowances for smooth insertion of a pipe. However, it is required to restrict the gap allowance within 0.2mm to avoid undesirable undercut on a welding bead.

• Journal of Biomedical Engineering Research
• /
• v.14 no.3
• /
• pp.235-242
• /
• 1993

In the early stage of sacroilitis, it is'difficult to detect sacroiliac(Sl) abnormalities by conventional plain X-ray even though there are characteristic symptoms of ankylosing spondylitis. 3 dimensional volume rendering from the CT image was performed to make an early de tection of the structural changes of Sl joint. 2 cases who had clinical impression of ankylosing spondylitis without sacroilitis in plane X-ray and 1 case of typical ankylosing spondylitis as well as 1 case of normal control were studied. The Sl Joints were separated and each joint surface of sacrum and ilium was independently reconstructed by a special 3D manipulation program. All 2 patiant who complained of inflammatory lower back pain with no abnormal findings in the plain X-ray showed structural changes in 3 dimensionally reconstructed surface Image of the Sl joint compared to the normal control. Authors tried several parameters, such as fourler analysis of each surface and the mean and variance of Sl joint gap. We couldn't tell the statistical significance because of the limited number of cases. However, the parameters showed difference according to the progression of disease.

• Journal of electromagnetic engineering and science
• /
• v.15 no.4
• /
• pp.199-205
• /
• 2015

An electromagnetic band gap (EBG) metamaterial construction is presented. A construction of a multipath mitigating ground plane, based on the EBG metamaterial is described. A method of the ground plane application and installation, which provides the multipath mitigating without spoiling antenna element phase center stability, is suggested and explained. A designed construction of GNSS antenna module, which contains the multipath mitigating ground plane, made from the presented EBG metamaterial and installed in the described way is shown and parameters of the antenna module are provided.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.17 no.1
• /
• pp.60-72
• /
• 1995

Temporomandibular joint ankylosis is the movemental obstacle of mandible which depend on proliferation of bony or fibrous tissue in temporomandibular joint structure by various causes. In order to treat this, various surgical methods have been performed, but no operative methods have been produced consistently successful results. This research has been performed to the patients who had been operated due to temporomandibular joint ankylosis by studying classification, cause, onset, duration, anesthesia and treatment method, symptom, change of mouth opening, complication through medical record, X-ray, follow-up for being a help to proper selection of treatment method and evaluation of prognosis. The author obtained the following results by analyzing 44 cases among patients who had been operated due to temporomandibular joint ankylosis during 8 year hospitalization from 1986 to 1993 in Dept. of Oral & Maxillofacial Surgery of Seoul National University Hospital. 1. The occurrence was in the order of below 10, 20's, 10's, 30's. The average of occurrence was 12.95. Illness period was 50.0% within 10 years and 50% beyond 10 years. The average period of illness was 13.33 years. 2. Trauma occupied 54.5% of causes and inflammation occupied 45.5%. Men had more occurrences due to trauma and there was no difference in case of inflammation. 3. In nasotracheal intubations for general anesthesia, the cases of using fiberoptic laryngoscope occupied 40.9%, direct or blind nasotracheal intubation occupied 40.9% and the cases of using tracheostomy occupied 18.2%. 4. In operative approaching methods, submandibular & preauricular approach were mainly applied, and in operative methods, high condylectomy(Group I) occupied 11.4%, arthroplasty without interpositional material following condylectomy or gap ostectomy(Group II) occupied 11.4%, with interpositional material following high condylectomy (Group III) occupied 40.9%, and using condylar reconstruction following condylectomy or gap ostectomy(Group IV) occupied 36.6%. 5. In change of mouth opening reformed after surgery, Group III showed the best result of average 23.5mm, Group IV showed 16.3mm, Group I showed 14.9mm and Group II showed 10.2mm of reformation. Summarizing the results as written above, it is considered that early treatment is important as soon as possible in Temporomandibular joint ankylosis. It is recommended in surgical method what can lead to postoperative early movement maintaining anatomaical & functional form, and then the development of various surgical methods will be requested.