• The Journal of the Korean dental association
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• v.46 no.4
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• pp.243-247
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• 2008

Purpose : Ridge expansion osteotomy (REO) has been introduced when it is necessary to expand narrow crestal ridge with simultaneous implant placement. This study has designed to evaluate the clinical availability of REO. Materials and methods : Subject were patients who had visited Seoul National University Bundang Hospital from July. 2003 to December, 2005 for implant placement using REO by one surgeon. Intraoperative and postoperative complication, failure of initial osseointegration and marginal bone resorption were estimated using electronic medical record and periapical radiography. Twenty?three patients, 8 males and 15 females, mean age 51, ranged 18 to 72, were treated for mean 26 months, ranged from 16 months to 46 months. Results : Mean diameter and length of implants placed at upper anterior, were 3.72mm and 13.32mm each other. Guided bone regeneration and ridge splitting were accompanied in this study. Five cases of cortical bone fracture, three cases of crestal bone loss more than 2mm, 2cases of gingival recession, and 2 cases of infection were noted, but there were no implants removed because of disintegration. Success rate of implant was 91.7%, even if survival rate of implant was 100%. In addition, there were no statistical significance between the success rate of REO and bone graft(p>0.05). Conclusion : Based on the results of the present study, it can be concluded that REO technique is reliable for implant placement at atrophic ridge with adequate height compared to bone graft and other osteotomies for ridge expansion, but care should be taken of esthetic problem such as gingival recession because of crestal bone resorption from trauma by osteotome.

• Journal of Periodontal and Implant Science
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• v.46 no.5
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• pp.337-349
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• 2016

Purpose: The aim of this study was to compare and analyze the peri-implant tissue conditions and prospective clinical outcomes associated with 2 types of hydroxyapatite (HA)-coated implants: (1) fully HA-coated implants and (2) partially HA-coated implants with resorbable blast medium on the coronal portion of the threads. Methods: Forty-four partially edentulous patients were randomly assigned to undergo the placement of 62 HA-coated implants, and were classified as the control group (partially HA-coated, n=30) and the test group (fully HA-coated, n=32). All patients had chronic periodontitis with moderate crestal bone loss around the edentulous area. The stability and clinical outcomes of the implants were evaluated using the primary and secondary implant stability quotient (ISQ), as well as radiographic, mobility, and peri-implant soft tissue assessments around the implants. The Wilcoxon signed-rank test and the Mann-Whitney test were used to evaluate differences between and within the 2 groups, with P values <0.05 considered to indicate statistical significance. Results: The fully HA-coated implants displayed good retention of crestal bone, and insignificant differences were found in annual marginal bone loss between the 2 types of HA-coated implants (P>0.05). No significant differences were found in the survival rate (group I, 100%; group II, 100%) or the success rate (group I, 93.3%; group II, 93.8%). The fully HA-coated implants also did not significantly increase the risk of peri-implantitis (P>0.05). Conclusions: The fully HA-coated implants did not lead to an increased risk of peri-implantitis and showed good retention of the crestal bone, as well as good survival and success rates. Our study suggests that fully HA-coated implants could become a reliable treatment alternative for edentulous posterior sites and are capable of providing good retention of the crestal bone.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.3
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• pp.432-438
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• 2002

In order to design and analyze the performance of an axial-flow pump it is necessary to know the flow deviation, deflection angle and pressure loss coefficient as a function of the angle of incidence for the hydrofoil section in use. Because such functions are unique to the particular section, however, general correlation formulae are not available for the multitude of hydrofoil profiles, and such functions must be generated by either experiment or numerical simulation for the given or selected hydrofoil section. The purpose of present study is to generate design correlations for hydrofoils with double circular arc (DCA) camber by numerical analysis using a commercial code, FLUENT. The cascade configuration is determined by a combination of the inlet blade angle, blade thickness, camber angle, and cascade solidity, and a total of 90 cascade configurations are analyzed in this study. The inlet Reynolds number based on the chord and the inlet absolute velocity is fixed at 5${\times}$10$\^$5/. Design correlations are formulated, based on the data at the incidence angle of minimum total pressure loss. The correlations obtained in this way show good agreement with the experiment data collected at NASA with DCA hydrofoils.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.574-580
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• 2007

The objective of this article is to present an analysis of all heat transfer paths through the energy nose under closed door conditions when refrigeration system of household refrigerator-freezer is operating on. Both experimental and numerical methods are suggested as a means of determining the overall energy nose load amount as well as the load due to each pathway such as mullion section and F and R sides of the household refrigerator-freezer. In other words, all loads determined in this article are just energy nose and not the loads seen by the refrigeration system. We suggest good ideas for improving the heat transfer losses such as conduction and convection through the energy nose. As we can be known from the experimental test results, it is effective to prevent the heat loss of a mullion section. And energy efficiency is also decreased approximately 6% compared to that of a baseline sample test result. As we can be known from the Ansys 8.1 analysis, it is shown the steady state temperature distribution in figures from 6 to 8. And the direction of the heat flow through the energy nose section is also easily seen from that In conclusion, the article is focused on an energy nose section in household refrigerator-freezer for practical proposes which is the energy saving in a household refrigerator-freezer. And the method suggested may be applied to any make or model to aid in the search for high efficient energy nose section of household side by side refrigerator-freezer as well as top mounted refrigerator-freezer, commercial refrigerator and so on.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.25-30
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• 2014

The flow characteristics of two types of overhung compressor volutes for automobile turbochargers were analyzed numerically using commercial software. For obtaining high performance from a volute, it is necessary that the volute have a high pressure recovery coefficient and a low loss coefficient. We investigated the flow characteristics of two types of overhung compressor volutes with a fixed diffuser inlet angle of $24^{\circ}$ and a mass flow rate of 0.055 kg/s. The first type is a volute with one-arc cross section (type 1) and the second type is with three-arc cross section (type 2). Our results showed that between the two types of volutes, type 2 had the higher pressure recovery coefficient and the lower loss coefficient along the entire angular position.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.85-92
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• 2018

PURPOSE. This research evaluated clinical outcomes of two types of hydroxyapatite (HA)-coated implants: OT (Osstem TS III-HA, Osstem implant Co., Busan, Korea) and ZM (Zimmer TSV-HA, Zimmer dental, Carlsbad, USA). MATERIALS AND METHODS. The research was conducted on 303 implants (89 of OT, 214 of ZM), which were placed from January 16, 2010 to December 20, 2012. The prognosis was evaluated in terms of success rates, survival rates, annual marginal bone loss, and implant stability quotients (ISQ). The samples were classified into immediate, early, conventional, and delayed groups according to the loading time. RESULTS. Overall, there were no significant differences between OT and ZM in success rates, survival rates, and annual marginal bone loss, except for the result of secondary stability. OT showed $77.83{\pm}8.23ISQ$, which was marginally higher than $76.09{\pm}6.90ISQ$ of ZM (P<.05). In terms of healing periods, only immediate loading showed statistically significant differences (P<.05). Differences between OT and ZM were observed in terms of two indices, the annual marginal bone loss ($0.17{\pm}0.58mm/year$ < $0.45{\pm}0.80mm/year$) and secondary stability ($84.36{\pm}3.80ISQ$ > $82.48{\pm}3.69ISQ$) (P<.05). OT and ZM did not have any statistically significant differences in early, conventional, and delayed loading (P>.05). CONCLUSION. OT (97.75%) and ZM (98.50%) showed relatively good outcomes in terms of survival rates. In general, OT and ZM did not show statistically significant differences in most indices (P>.05), although OT performed marginally better than ZM in the immediate loading and 1-stage surgery (P<.05).

• The Journal of Advanced Prosthodontics
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• v.4 no.1
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• pp.18-23
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• 2012

PURPOSE. The purpose of this prospective study was to evaluate the effect of early loading on survival rate or clinical parameter of anodic oxidized implants during the 12- month postloading period. MATERIALS AND METHODS. Total 69 implants were placed in 42 patients. Anodic oxidized implants (GS II, Osstem Cor., Busan, Korea) placed on the posterior mandibles were divided into two groups, according to their prosthetic loading times: test group (2 to 6 weeks), and control group (3 to 4 months). The implant survival rates were determined during oneyear postloading period and analyzed by Kaplan-Meier method. The radiographic peri-implant bone loss and periodontal parameters were also evaluated and statistically analyzed by unpaired t-test. RESULTS. Total 69 implants were placed in 42 patients. The cumulative postloading implant survival rates were 88.89% in test group, compared to 100% in control group (P<.05). Periimplant marginal bone loss (T: $0.27{\pm}0.54$ mm, C: $0.40{\pm}0.55$ mm) and periodontal parameters showed no significant difference between the groups (P>.05). CONCLUSION. Within the limitation of the present study, implant survival was affected by early loading on the anodic oxidized implants placed on posterior mandibles during one-year follow-up. Early implant loading did not influence peri-implant marginal bone loss, and periodontal parameters.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.4
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• pp.225-231
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• 2022

Objectives: This study aims to evaluate the efficacy and safety of two types of sandblasted with large-grit and acid-etched (SLA) surface implants with different surface roughness. Patients and Methods: This study was conducted based on a clinical record review of 55 patients (mean age, 53.00 years). A total of 80 SLA surface implants was placed. Among the 80 implants, 38 implants placed in 29 subjects had surface roughness (Ra) of 3.09 ㎛ (test group, TG), while the other 42 implants placed in 31 subjects had a surface roughness (Ra) of 2.50 ㎛ (control group, CG). A comparison was made of implant primary/secondary stability; success and survival rates; marginal bone loss; and soft tissue assessment including probing pocket depth (PPD), plaque index (PI), gingival index (GI), and bleeding on probing (BOP) between the groups at 1 year after implant placement. Results: Among the implants that were initially registered, 1 from the TG and 4 from the CG dropped out, leaving 37 implants in the TG and 38 implants in the CG to be traced and analyzed. Although 1 TG case showed unstable primary stability, all cases showed stable secondary stability. Success and survival rates at 1 year after implant placement were 100% in both groups. Marginal bone loss was 0.07 mm and 0.00 mm for the TG and CG, respectively, but the difference was not significant. Among the several parameters for evaluation of soft tissue, the TG showed lower PI at 1 year after implant placement (TG=0.00, CG=0.29; P=0.0004), while the remaining categories showed no significant difference between the groups. Conclusion: This study shows that the two types of SLA implants with different surface roughness have no difference in efficacy or safety. Therefore, both of the implants can be used safely and with promising outcomes.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.63-70
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• 2009

Failure modes result in fracture or tearing, which may cause deterioration of resistance and reduction of inelastic deformation capacity. The potential failure modes for Special Concentrically Braced Frames (SCBFs) include fracture or tearing of the brace, net section fracture of the brace or gusset plate, fracture of the gusset plate welds, shear fracture of the bolts, block shear, excessive bolt bearing deformation, and buckling of the gusset plate. HSS tubular braces are commonly used in SCBFs, and net section fracture of the tubular brace may also occur through the brace net section at the end of the slot cut into the tube to slip over the gusset plate. This failure mode is categorized as a tension failure mode, and may cause dramatic loss of resistance and brittle behavior. Net section reinforcement is required according to AISC design specifications (AISC 2001). In this paper, the need to reinforce the net section area was discussed. Initially, the results of the net section fracture tests done by the University of California in Berkeley were presented with the modeling of these tests using FE models. To investigate the possibility of net section fracture in an actual frame, the slot end hole model was adapted to the frame FE model, and alternate near-fault histories were applied with tension-dominated cycles, since previous analyses showed that loading history was the most critical factor in net section fracture. The need for this reinforcement (cover plate) and the tension-dominated near-fault history were investigated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.978-982
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• 2010

For mass information transfer, the optical communication using optic fiber has been widely used. Especially, in the field of medical image, the large data is digitalized based on the standard image and it is used for telemedicine with this method. Therefore, to transfer the large amount of data fast and effectively POF (Plastic Optical Fiber) can be used and the development of optic connector for connection between POFs is very important. In this study, for stable optical coupling of POF optic fiber Ferrule and Sleeve were designed and produced by considering the bond stability and the insertion loss according to the physical contact and roughness profile was evaluated. As a result of examining the insertion loss by physical contact method of two optic fibers, it showed the loss was about 1.895dB. According to the results from studying the condition of grinding section for POF mass production, the mass production condition was established as POF profile roughness of 6nm and the loss of 0.2dB or lower by controlling the film size and time step by step.