• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.253-263
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• 2015

Ultra-high strength concrete which have 100 MPa compressive strength or higher can be developed applying RPC(Reactive Powder Concrete). Preventing brittle failure under compression and tension, ultra-high strength concrete usually use the steel fibers as reinforcements. For the effective use of steel fiber reinforced ultra-high strength concrete, estimation of tensile strength is very important. However, there are insufficient research results are available with no relation between them. Therefore, in this study, correlation between compressive strength and tensile strength of ultra-high strength concrete was investigated by test and statistical analysis. According to test results, increasing tendency of tensile strength was also shown in the range of ultra-high strength. Evaluation of test results of this study and collected test results were carried out. Using 284 splitting test specimens and 265 flexural test specimens, equations suggested by previous researchers cannot be applied to ultra-high strength concrete. Therefore, using database and test results, regression analysis was carried out and we suggested new equation for splitting and flexural tensile strength of steel fiber reinforced ultra-high strength concrete.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.261-269
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• 2013

In this study, it was developed eco-friendly inorganic binding material concrete using ground granulated blast furnace slag and alkali activator (water glass, sodium hydroxides). Eight reinforced concrete beam using inoganic binding material concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, type of admixture and admixture. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The eco-friendly concrete using inorganic binding material encouraged alkali activation reaction was rapidly hardening speed and showed possibility as a high strength concrete. Also, the RC beams using new materials showed similar behavior and failed similarly with RC beam used portland cement. It is thought that eco-friendly inorganic binding material concrete can be used with construction material and product as a basic research to replace cement concrete. If there is application to structures in PC member as well as production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.393-403
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• 2011

The purpose of this study was to analyze and compare survival rates of resorbable blast media(RBM) surface and acid-etched surface implants being usually used in clinics. RBM surface implants (USII, Osstem, Busan, Korea) or acid-etched surface implants ($Osseotite^{(R)}$, Biomet $3i^{[TM]}$, FL, USA) were placed in edentulous area of 140 patients between January of 2005 and March of 2007. The number of implants was 304, and 152 out of them were RBM surface implants while another 152 were acid-etched surface implants. According to the evaluation items, the survey was performed before and after the implants installations. The 3-year survival rates of both kind of implants were calculated. 1. Total of 152 RBM surface implants were placed. Among them, one implant was failed, which was implanted in the posterior mandible with D2 bone quality. The failure was resulted from fracture of the fixture. Others showed good results and survival rate of RBM surface implant was 99.34%. 2. Total of 152 acid-etched surface implants were placed. Seven implants of them were failed, thus, survival rate was 95.39%. The causes of the failures were considered as infection, overheat and the lack of initial stability. In this research, both implants showed good 3-year survival rate, although RMB surface implant represented a better result.

• Journal of Periodontal and Implant Science
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• v.49 no.6
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• pp.382-396
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• 2019

Purpose: The purpose of this study was to elucidate the efficacy and safety of carbonate apatite (CO₃Ap) granules in 2-stage sinus floor augmentation through the radiographic and histomorphometric assessment of bone biopsy specimens. Methods: Two-stage sinus floor augmentation was performed on 13 patients with a total of 17 implants. Radiographic assessment using panoramic radiographs was performed immediately after augmentation and was also performed 2 additional times, at 7±2 months and 18±2 months post-augmentation, respectively. Bone biopsy specimens taken from planned implant placement sites underwent micro-computed tomography, after which histological sections were prepared. Results: Postoperative healing of the sinus floor augmentation was uneventful in all cases. The mean preoperative residual bone height was 3.5±1.3 mm, and this was increased to 13.3±1.7 mm by augmentation with the CO₃Ap granules. The mean height of the augmented site had decreased to 10.7±1.9 mm by 7±2 months after augmentation; however, implants with lengths in the range of 6.5 to 11.5 mm could still be placed. The mean height of the augmented site had decreased to 9.6±1.4 mm by 18±2 months post-augmentation. No implant failure or complications were observed. Few inflammatory cells or foreign body giant cells were observed in the bone biopsy specimens. Although there were individual differences in the amount of new bone detected, new bone was observed to be in direct contact with the CO₃Ap granules in all cases, without an intermediate layer of fibrous tissue. The amounts of bone and residual CO₃Ap were 33.8%±15.1% and 15.3%±11.9%, respectively. Conclusions: In this first demonstration, low-crystalline CO₃Ap granules showed excellent biocompatibility, and bone biopsy showed them to be replaced with bone in humans. CO₃Ap granules are a useful and safe bone substitute for two-stage sinus floor augmentation.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.27-40
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• 2003

In the present study, a newly modified soil nailing technology named as the PSN(Pretension Soil Nailing) system is proposed. Effects of various factors related to the design of the pretension soil nailing system, such as the length of a sheathing pipe and the fixed cone, are examined throughout a series of the displacement-controlled field pull-out tests. 9 displacement-controlled field pull-out tests are performed in the present study and the pretension forces are also evaluated based on the measurements. In addition, both short-term and long-term characteristics of pull-out deformations of the newly proposed PSN system are analyzed and compared with those of the general soil nailing system by carrying out the stress-controlled field pull-out tests. A numerical approach is further made to determine a postulated failure surface as well as a minimum safety factors of the proposed PSN system using the shear strength reduction technique and the $FLAC^{2D}$ program. Global minimum safety factors and local safety factors at various excavation stages computed in case of the PSN system are analyzed throughout comparisons with the results expected in case of the general soil nailing system. An efficiency of the PSN system is also dealt with by analyzing the wall-facing deformations and the adjacent ground surface settlements.

• Korean Journal of Social Welfare
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• v.68 no.4
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• pp.119-141
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• 2016

This study analyzed on the basis of the norms and experience the Seongnam youth dividend ordinance. Youth dividend pros in the normative dimension to understand in order to achieve social justice. Further, youth dividend can replace the existing policy. On the other hand, the opposite of youth dividend is pointed out that the policy is ambiguous without morally justifiable. Also it has been pointed out inefficiencies means. Youth dividend Pros empirical dimension is a social considerations measures, there is a need for innovation by the failure of existing measures. On the other hand, youth dividend opposed to target efficiency is low, and that the problem is often to the contents of the salary. Because both sides are too contrast, consensus is difficult, can be political point of view is a significant impact. The basic income is a new thought experiment for human self-realization. Therefore, the production social welfare policy personality is a different policy science. That is, it is a long-term care social policy that requires a holistic life support. In addition, a non-empirical policy that requires a material support for the substantial freedom. Therefore, it is necessary to understand the philosophical meaning than scientific evaluation of traditional policy aiming to realize autonomous life. Therefore, radio waves of basic income through the welfare politics and exercise is still important strategy.

• Composites Research
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• v.29 no.6
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• pp.408-413
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• 2016

Commonly-used polymers are manufactured as versatile forms. Furthermore, continuous polymer fibers are recently manufactured using nylon or aramid fiber. One of common epoxy was also used to make polymer fibers. Bisphenol-A type was used as base epoxy whereas amine and anhydride were used as hardeners. Epoxy fibers was cured by stepping up the temperature to maintain the shape of epoxy fiber. Surface energy was measured to confirm the degree of interfacial adhesion by modified static contact angle method. After mechanical properties were measured via fiber tensile test, the evaluation of fiber fracture was proceeded. Tensile strength of epoxy fiber using amine type hardener was higher as 138 MPa than anhydride case as 70 MPa. Fractured surface exhibited different failure patterns at the cross-section.

• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.205-212
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• 2017

Chronic diffuse hepatopathy is one of the important clinical tasks to reduce mortality and morbidity due to liver cirrhosis, liver failure, and liver cancer. The purpose of this study was to evaluate the criteria for predicting liver and chronic liver disease using Fibroscan based on ultrasound diagnosis. Serum and liver stiffness measurement(kPa) were analyzed in 280 patients and cut-off values of liver stiffness measurement for predicting fatty liver and chronic diffuse hepatopathy were determined using ROC curve analysis. Bilirubin and PT(prothrombin time) were not related to disease prediction(p=0.243, p=0.115). Serum glucose and triglyceride levels were significantly higher in the liver (p<0.05). The cut-off value for predicting chronic diffuse hepatopathy was determined as 10.3 kPa(AUC 0.98, sensitivity 94.94%, specificity 94.93%) in the order of control group, fatty liver and chronic diffuse hepatopathy. Therefore, it will be used as a primary tool for the diagnosis of chronic liver disease patients with quantitative evaluation.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.298-305
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• 2018

Rhomboid family member 2 gene (Rhbdf2) is an inactive homologue lacking essential catalytic residues of rhomboid intramembrane serine proteases. The protein is necessary for maturation of tumor necrosis factor-alpha ($TNF-{\alpha}$) converting enzyme, which is the molecule responsible for the release of $TNF-{\alpha}$. In this study, Rhbdf2 knockout (KO) mice were produced by CRISPR/CAS9. To see the effects of the failure of $TNF-{\alpha}$ release induced by Rhbdf2 gene KO, collagen-induced arthritis (CIA), which is the representative $TNF-{\alpha}$ related disease, was induced in the Rhbdf2 mutant mouse using chicken collagen type II. The severity of the CIA was measured by traditional clinical scores and histopathological analysis of hind limb joints. A rota-rod test and grip strength test were employed to evaluate the severity of CIA based on losses of physical functions. The results indicated that Rhbdf2 mutant mice showed clear alleviation of the clinical severity of CIA as demonstrated by the significantly lower severity indexes. Moreover, a grip strength test was shown to be useful for the evaluation of physical functional losses by CIA. Overall, the results showed that the Rhbdf2 gene has a significant effect on the induction of CIA, which is related to $TNF-{\alpha}$.

• Information Systems Review
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• v.11 no.2
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• pp.45-66
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• 2009

A number of companies are considering for merger and acquisition (M&A) as one of business strategies for their growth and survival. However, many of them do not create the synergy they had sought, and failed M&A, often result in negative outcomes in terms of productivity, market share, profitability and turnover of qualified employees. There have been numerous research studies conducted to analyze the factors that determine the success and failure of M&A, and it has been found that with the increasing dependence of many companies on information systems, post-M&A IS (information systems) integration success has a critical effect on the success of M&A. However, there have been very few studies on post-M&A IS integration success, and most have been restricted to integration of IS organizations or physical information systems. In order to conduct a comprehensive research on the factors that affect the success of post-M&A IS integration, this study surveyed preceding researches on not only information systems but also strategic management, economics, finance, HRM (human resource management) and organization management. Based on the findings, a comprehensive and integrated model of the influential factors on post-M&A IS integration has been proposed. The proposed model categorizes the factors into perspectives of M&A, strategy, organization, HRM and IS, and provides an empirical evaluation of each factor on the success of IS integration based on comparative case studies.