• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.280-292
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• 2016

Purpose: The purpose of this study was to compare the long-term survival rate and peri-implant marginal bone loss related to multiple risk factors including the clinician's experience. Materials and Methods: Four hundred twenty implants in 146 patients, who had involved a supportive periodontal therapy program every 3 to 6 months and had follow up data for at least 5 years, were selected as the study group. Peri-implant marginal bone loss, data of demographic, implant and surgical characteristics were collected from peri-apical radiographs and chart review. Implant survival was regarded as the remaining with radiographic marginal bone level in excess of 50% of the fixture length for any reason. Results: The cumulative survival rate after 5 years of loading was 94.9%. In binary logistic regression analysis, smoking status (P = 0.033) and presence of spontaneous cover screw exposure (P < 0.001) were significantly related to 5-year survival of implants. In stepwise multiple regression analysis, smoking status (P < 0.001), type of abutment connection (P < 0.001) and implant surface (P = 0.033) were significantly related to peri-implant marginal bone level. And the year of resident was not statistically related to 5-year implant survival in simple logistic regression analysis (P = 0.171). Conclusion: Smoking status, spontaneous cover screw exposure, type of abutment connection and implant surface might influence the implant success. There was no significant correlation between the year of resident and implant failure.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.281-288
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• 2008

Recently, the advance of multimedia hardware has fostered the development of wireless multimedia sensor network which is able to ubiquitously obtain multimedia content such as image or audio from the environment. The multimedia data which has several characteristics such as large size and correlation between the data requires reliability in transmission. However, the existing solution which take the focus on the efficiency of network mainly, is not appropriate to transmit the multimedia data. In the paper, we proposes a reliable asynchronous image transfer protocol, RAIT. RAIT applies double sliding window method in node-to-node image tansfer to prevent the packet loss caused by network congestion. The double sliding window consists of one sliding window for the receiving queue, which is used for prevention of packet loss caused by communication failure between nodes and the other sliding window for the sending queue which prevents the packet loss caused by network congestion. the routing node prevents the packet loss and guarantees the fairness between the nodes by scheduling the packets based on the image non-preemptively. The RAIT implements the double sliding window method by cross layer design between RAIT layer, routing layer, and queue layer. The experiment shows that RAIT guarantees the reliability of image transmission compared with the existing protocol.

• Restorative Dentistry and Endodontics
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• v.29 no.6
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• pp.504-514
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• 2004

This study compared the dentin shear bond strengths of currently used dentin bonding agents that were irradiated with an LED (Elipar FreeLight, 3M-ESPE) and a halogen light (VIP, BISCO). The optical characteristics of two light curing units were evaluated. Extracted human third molars were prepared to expose the occlusal dentin and the bonding procedures were performed under the irradiation with each light curing unit. The dentin bonding agents used in this study were Scotchbond Multipurpose (3M ESPE), Single Bond (3M ESPE), One-Step (Bisco), Clearfil SE bond (Kuraray), and Adper Prompt (3M ESPE), The shear test was performed by employing the design of a chisel-on-iris supported with a Teflon wall. The fractured dentin surface was observed with SEM to determine the failure mode. The spectral appearance of the LED light curing unit was different from that of the halogen light curing unit in terms of maximum peak and distribution. The LED LCU (maximum peak in 465 nm) shows a narrower spectral distribution than the halogen LCU (maximum peak in 487 nm). With the exception of the Clearfil SE bond (P < 0.05), each 4 dentin bonding agents showed no significant difference between the halogen light-cured group and the LED light-cured group in the mean shear bond strength (P > 0.05). The results can be explained by the strong correlation between the absorption spectrum of camphoroquinone and the narrow emission spectrum of LED.

• Journal of Yeungnam Medical Science
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• v.7 no.1
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• pp.69-80
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• 1990

A clinical analysis was done on 23 patients(24 hips) with fracture of the femoral neck, who had been admitted and treated at our Orthopedic department during the period of 4 years, from Jan, 1984 to May 1988. The results were as follows : 1. 23 patients were comprised of 4 males and 19 females, and 11 patients were over 65 years old. 2. 18 cases of 24 cases were due to minor traumas such as slipping down, and for over 65 years old, all cases were due to simple minor traumas, 8 cases were showed a severe osteoporosis, below grade 3 of the Singh's index. 3. 14 cases of 24 cases were displaced subcapital fractures, and 6 cases displaced transcervical fractures. Only 4 cases were the undisplaced transcervical fractures. 4. In treatment of fractures internal fixations after manipulation were performed in 14 cases and primary arthroplasties in 10 cases. Secondary arthroplasties were done in complicated 4 cases of 14 cases treated with internal fixations. 5. Complications after internal fixation were developed in 7 cases out of 14 cases, avascular necrosis in 6, nonunions in 2, pin migrations in 3, and metal failure in 1 case. 6. In 14 arthroplasty immediate surgical fitness of femoral stem were related to late loosening of femoral stem(correlation coefficient r=-0.68, p<0.01).

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.49-52
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• 2022

As the difficulty of flip chip products increase, interest in stable PKG material technology from the viewpoint of reliability is increasing. Currently, the representative of poor reliability that are mainly occurring in flip chip PKG are Sn bridge and Cu dendrite. Two type defects are caused by void generated by the flux residue around the bump. In order to essentially minimize the risk of this type of reliability failure, the linkage between the composition of Molded Under-fill (MUF) and flux, which is related material, was reviewed. In this study, the correlation between base resin and filler, which is the main component of MUF, and flux, was defined, and the material composition design was carried out by refer to lesson learn. With the current material composition, it was confirmed that moisture absorption reliability 85%/85%/24hrs pass result and void did not occur during destructive analysis, and developed MUF has shown flux immunity improving result in flip Chip PKG. We think this study can be used in yield enhancement of flip chip process and give insights to study in compatibility between MUF and flux.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.51-62
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• 2020

The study was conducted to verify the causality of the ability of high school and college dance majors to influence the successful goal orientation and how the change in goal affects the sense of dance performance self-confidence. In this regard, 172 dance majors were collected to collect data on their belief in dance ability, the direction of mastery goal of approach and avoidance, and the measure of confidence in dance performance, and the results of their studies were derived through correlation and structural equation analysis and path analysis. The analysis results showed reasonable factor structure and reliability based on the preceding study of feasibility analysis results between variables. Thus, the structural equation for the study variables confirmed that the theoretical hypothesis was suitable, and the path of each variable was verified through the path analysis. The analysis showed that the increased belief that ability can be improved by effort has been found to improve the effort and consequently the confidence in dancing. Also, the fixed belief that ability is not changing in a fixed sense has been found to affect the avoidance goal and reduce confidence. It can be interpreted that the more one believes that one can change one's ability by effort, the more one strengthens one's actions to achieve one's goal, thereby improving one's dance confidence. Therefore, it is deemed necessary for subsequent studies to explore whether the paths of these models differ by their major or dance careers, and to apply variables that can measure the success or failure of actual performances to enhance the explanatory power of these research variables.

• Journal of Korea Trade
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• v.25 no.3
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• pp.21-47
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• 2021

Purpose - Offshoring has emerged as one of the major trends in international trade and has become one of the strategies for achieving competitiveness in the global market. In spite of this, the expected gains of offshoring can be offset by hidden costs and risks, such as those associated with the COVID-19 pandemic, the trade war between the USA and China, and the ongoing trade dispute between Korea and Japan. To obviate such business failure and prevent critical business blunders, offshoring strategies that efficiently consider both risk elements and potential wealth creation are urgently need. The first purpose of this study is to contribute to the development of more advanced offshoring strategies to help host countries select the best locations to manage supply chain risks and create unique value. The second purpose is to specifically analyze the current status of Korea and provide Korean companies with implications to be considered when deciding whether to offshore or re-shore. Design/methodology - A Network DEA model was applied to measure the comparative location efficiency of national competencies for offshoring strategy from perspectives of wealth creation opportunities (profitability and marketability) and supply chain risk management. The location efficiencies are compared among a total 70 countries selected from the Global Competitiveness Index (GCI) and globally attractive locations outlined by Kearney (2017). For the secondary analysis of efficiency, a t-test examining the nature of competitive advantage and the level of sophistication in production processes was implemented in three divisions. We then analyzed differences in offshoring performance in terms of the identified national traits. Moreover, Tobit regression analysis is conducted to investigate the correlation between value-added business activities and each divisional efficiency, seeking to determine how each degree of value-added business activity influences the increase in offshoring productivity. Findings - Regarding overall location efficiency for offshoring performance, only the USA and Italy were identified as being efficient as host countries for offshoring, under circumstances of advanced development, such as productivity and risk management. Korea ranks 13th among 70 countries. The determinants of national competitiveness depend on national traits (the nature of competitive advantage and business sophistication). Countries with labor/resource advantages and labor-intensive industries are more competitive in terms of marketability than others. In contrast, countries with strong technology-intensive industries benefit offshoring companies, particularly in the technology sector, with the added advantage of supply chain risk management. As the perception of a value chain is broader in a country, it can achieve both production sophistication and competitive advantages such as marketability and SCRM. Originality/value - Existing studies focus on offshoring effectiveness from a company perspective. This paper contributes to comparing country efficiency in producing core competencies related to an offshoring strategy and also segments countries into three performance-based considerations associated with the global offshoring market. It also details Korea's position as an offshoring location according to national efficiency and competency.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.42-49
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• 2021

This study aimed to evaluate the long-term outcomes of teeth treated with reattachment technique in children and adolescents. Twenty seven permanent anterior teeth from 21 patients treated with fragment reattachment were evaluated. Clinical photos and medical records were used to assess treatment outcomes. Effect of pulp treatment and the ratio of fragment on success rate were statistically analyzed. Detachment of fragment was observed in 17 teeth, and their duration of retention was 21.41 ± 23.39 months. Repeated trauma was found to be the most frequent causes of failure. Pulp treatment before reattachment did not affect the success rate (p > 0.05). The mean ratio of fragment was 0.482 ± 0.147, and the success rate was affected by the ratio of fragment (p = 0.018). The median retention time of the teeth was 72 months if the ratio was under 0.5, and 8 months for that of the others. A significant correlation was found between the ratio of fragment and retention time (p = 0.003). Reattachment can be a predictable treatment option for crown fracture in anterior teeth in children and adolescents when a fracture involves less than 50% of the clinical crown.

• Journal of the Korea Institute of Building Construction
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• v.23 no.3
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• pp.305-313
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• 2023

With an increasing interest in the commercialization of research results in the present societal climate, especially in the construction industry, preliminary product analysis plays a critical role when introducing a new product to the market. It significantly influences the product's success or failure. In this context, this study aims to investigate the utility of Importance-Performance Analysis (IPA) as a management strategy tool for preliminary analysis in the commercialization of new architectural technologies. The study specifically assesses a smart ball product engineered for pipeline inspection. The evaluation is carried out based on product quality, convenience, and usability categories. Seventeen factors are recognized as sub-items, and a survey is conducted among relevant experts and consumer groups. From the survey, four key items are chosen: "Keep up the good work," "Concentrate here," "Low priority," and "Possible overkill." Suitable strategic measures are derived for each item. By conducting a correlation analysis between product importance and performance, this study offers a method to establish priority directions for future development. This analysis assists in identifying areas that necessitate improvement or additional focus to increase the product's commercial potential. On the whole, this study contributes to understanding and applying Importance-Performance Analysis as a valuable tool in the preliminary analysis and commercialization of novel technologies in the field of architecture.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.3
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• pp.184-191
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• 2023

With increasing corrosion in RC (Reinforced Concrete) structures, cracks occurred due to corrosion products and bearing load resistance decreased. In this study, corrosion was induced through an accelerated corrosion test (ICM: Impressed Current Method) with 140 hours of duration, and changes in USV (Ultra-Sonic Velocity), flexural failure load, and corrosion weight were evaluated before and after corrosion test. Three levels of cover depth (20 mm, 30 mm, and 40 mm) were considered, and the initial cracking period increased and the rust around steel decreased with increasing cover depth. In addition, the USV linearly decreased with decreasing cover depth and increasing amount of corrosion. In the flexural loading test, the bending capacity decreased by more than 10% due to corrosion, but a clear correlation could not be obtained since the corrosion ratio was small, so that the effect of slip was greater than that of reduced cross-sectional area of steel due to corrosion. As cover depth increased, the produced corrosion amount and USV changed with a clear linear relationship, and the cracking period due to corrosion could be estimated by the gradient of the measured corrosion current.