• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.105-119
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• 2005

Statement of problem. As the effects of the various diameters of fixture and abutment screw on stress distribution was not yet examined, this study focused on the different design of single implant restoration using three dimensional finite element analysis. Purpose. This study was to compare five different fixture-abutment combinations for single implant supported restorations with different fixture and abutment screw diameters. Material of methods. The five kinds of finite element models were designed by 3 diameter fixtures ($\oslash$3.3, 3.75, 5.0 mm) with 3 different abutment screws $\oslash$1.5, 1.7, 2.0 mm). The crown for mandibular first molar was made using UCLA abutment according to Wheeler's anatomy. 244 N was applied at the central fossa with two different loading directions, vertically and obliquely (30$^{\circ}$) and at the buccal cusp vertically. Maximum von Mises stresses were recorded and compared in the supporting bone, crowns, fixtures, and abutment screws. Results. 1. The stresses in supporting bone and implant-abutment structure under oblique loading were greater than those under vertical or offset loading. The stresses under vertical loading were the least among 3 loading conditions regardless of the implant and abutment screw diameters. 2. The stresses in the narrow implants were greater than the wider implants. The narrow implant with narrow abutment screw showed highest stresses in the lingual crest, but the narrow implant with standard abutment screw showed highest stress in abutment screw. 3. The stresses of abutment screws were influenced by the diameter of fixtures and loading conditions. The wide implants showed least difference between two different abutment screw diameters. Conclusions. The wide implants showed lesser stresses than the narrow implants and affected least by the different abutment screw diameters. The narrow implants with standard abutment screw showed highest stresses in the lingual bony crest under oblique loading.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.74-75
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• 2014

In remodeling business or construction of both new strucures and existing structures, Case that pile foundation was set is often. Micro pile, holding compressive force and tensile force by spherical friction, is supported by skin friction rather than end bearing capacity. but, This is weak in tension. Active area of micro pile's skin friction is narrow and micro pile don't do unification behavior hence. So bearing capacity was not fully mobilized in existing researching. In this study, in order to compensate for this method, micro pile to install Resisting Fixture is proposed.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.789-798
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• 2005

Primary stability is a fundamental criteria of implant success. There has been various trials to increase initial stability and bone to implant contact. The objective of osteotome technique is to preserve all the existing bone by minimizing or even eliminating the drilling sequence of the surgical protocol. The bone layer adjacent to the osteotomy site is progressively compacted with various bone condensers(osteotomes) this will result in a denser bone to implant contact. This improved bone density helps to optimize primary implant stability in low density bone. The use of wide implant is one of methods to increse primary stability. They can be used in special situations in which they can increase the surface area available for implant anchorage and improve their primary stability The aim of this study was to evaluate the influence of the osteotome technique and implant width on primary stability. Osteotome technique was compared with conventional drilling method by resonance frequency measurments according to the implant fixtures diameter. The results were as follows: 1. The average of ISQ value was sightly higher in osteotome technique, but there was not statistically significant in regular and narrow implant(p <0.05). 2. Either osteotome technique or conventional technique. ISQ value was significantly higer as increasing of implant diameter(p <0.05). 3. ISQ value of drilling technique was higer than those of osteotome technique in wide implant. It was assumed to be caused by difference in final preparation diameter.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.4
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• pp.291-298
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• 2017

It is challenging to produce esthetic implant restoration in the narrow anterior maxilla region where insufficient volume of alveolar bone could limit the angle and position of implant fixture, if preceding bone augmentation is not considered. Ideal angle and position of implant fixture placement should be established to reproduce harmonious emergence profile with marginal gingiva of implant prosthesis, bone augmentation considered to be preceded before implant placement occasionally. In this case, preceding bone augmentation has been operated before esthetic implant prosthesis in narrow anterior maxilla region. Preceded excessive bone augmentation in buccal area allowed proper angulation of implantation, which compensates unfavorable implant position. Provisional restorations were corrected during sufficient period to make harmonious level of marginal gingiva and interdental papilla. The definite restoration was fabricated using zirconia core based glass ceramic. Functionally and esthetically satisfactory results were obtained.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.2.1-2.9
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• 2015

Background: The aim of this study was to evaluate the effect of autogenous tooth bone as a graft material for regeneration of bone in vertical bony defects of the minipigs. Material and Methods: Six minipigs were used in this study. Four molars were extracted in the right mandibular dentition and sent to the Korea Tooth Bank for fabrication of autogenous tooth bone. Ten days later, each extraction site was implanted with MS Implant Narrow Ridge $3.0{\times}10mm$ fixture (Osstem, Seoul, Korea) after standardized 2mm-sized artificial vertical bony defect formation. Pineappleshaped Root-On type autogenous tooth bones were applied to the vertical defects around the neck area of the posterior three fixtures and the fore-most one was not applied with autogenous bone as a control group. Each minipig was sacrificed at 4, 8, 12 weeks after fixture installation and examined radiologically and histologically. Histological evaluation was done under light microscope with Villanueva osteochrome bone staining with semi-quantitative histomorphometric study. Percentage of new bone over total area (NBF) and bone to implant contact (BIC) ratio were evaluated using digital software for area calculation. Result: NBF were $48.15{\pm}18.02%$, $45.50{\pm}28.37%$, and $77.13{\pm}15.30%$ in 4, 8, and 12 weeks, respectively for experimental groups. The control group showed $37.00{\pm}11.53%$, $32.25{\pm}26.99%$, and $1.33{\pm}2.31%$ in 4,8,12 weeks, respectively. BIC ratio were $53.08{\pm}19.82%$, $45.00{\pm}28.37%$, and $75.13{\pm}16.55%$ in 4,8,12 weeks, respectively. Those for the control groups were $38.33{\pm}6.43%$, $33.50{\pm}29.51%$, and $1.33{\pm}2.31%$ in 4, 8, 12 weeks, respectively. Conclusion: Autogenous tooth bone showed higher score than control group in NBF and BIC in all the data encompassing 4,8,12 weeks specimens, but statistically significant only 12 weeks data in both NBF and BIC.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.155-162
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• 2018

PURPOSE. The aim of this study was to compare the fracture of implant component behavior of external and internal type of implants to suggest directions for successful implant treatment. MATERIALS AND METHODS. Data were collected from the clinical records of all patients who received WARANTEC implants at Seoul National University Dental Hospital from February 2002 to January 2014 for 12 years. Total number of implants was 1,289 and an average of 3.2 implants was installed per patient. Information about abutment connection type, implant locations, platform sizes was collected with presence of implant component fractures and their managements. SPSS statistics software (version 24.0, IBM) was used for the statistical analysis. RESULTS. Overall fracture was significantly more frequent in internal type. The most frequently fractured component was abutment in internal type implants, and screw fracture occurred most frequently in external type. Analyzing by fractured components, screw fracture was the most frequent in the maxillary anterior region and the most abutment fracture occurred in the maxillary posterior region and screw fractures occurred more frequently in NP (narrow platform) and abutment fractures occurred more frequently in RP (regular platform). CONCLUSION. In external type, screw fracture occurred most frequently, especially in the maxillary anterior region, and in internal type, abutment fracture occurred frequently in the posterior region. placement of an external type implant rather than an internal type is recommended for the posterior region where abutment fractures frequently occur.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.73-80
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• 2004

A dual purpose robot automation system is developed for both arc welding and spot welding by one robot within a cell. The need for automation of both arc welding and spot welding processes is urgent while the production volume is not so big as to accommodate separate station for the two processes. Also, space is too narrow for separate station to be settled down in the factory. A spot welding robot is chosen and the function for arc welding are implemented in-house at cost of advanced functions. For the spot welding, a single pole type gun is used and the robot has to push down the plate to be welded, which causes the robot positioning error. Therefore, position error compensation algorithm is developed. The basic functions for the arc welding processes are implemented using the digital I/O board of robot controller, PLC, and A/D conversion PCB. The weaving pattern is taught in meticulously by manual teach. A fixture unit is also developed for dual purpose. The main aspects of the system is presented in this paper especially in the design and implementation procedure. The signal diagrams and sequence logic diagrams are also included. The outcome of the dual purpose welding cell is the increased productivity and good production stability which is indispensable for production volume prediction. Also, it leads to reduction of manufacturing lead time.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.6
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• pp.13-19
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• 1995

A dual purpose robot automation system is developed for both arc welding and spot welding by one robot within a cell. The need for automation of both arc welding and spot welding processes is urgent while the production volume is not so big as to accommodate separate stations for the two processes. Also, space is too narrow for separate stations to be settled down in the factory. A spot welding robot is chosen and the functions for arc welding are implemented in-house at cost of advanced functions. For the spot welding, a single pole type gun is used and the robot has to push down the plate to be wolded, which causes the robot positioning error. Therefore, position error compensation algorithm is developed. The basic functions for the arc welding processes are implemented using the digital I/O board of robot controller, PLC, and A/D conversion PCB. The weaving pattern is taught in meticulously by manual teach. A fixture unit is also developed for dual purpose. The main aspects of the system is presented in this paper especially in the design and implementation procedure. The signal diagrams and sequence logic diagrams are also included. The outcome of the dual purpose welding cell is the increased productivity and good production stability which is indispensable for production volume prediction. Also, it leads to reduction of manufacturing lead time.