• Journal of the Korean Society for Railway
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• v.9 no.4 s.35
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• pp.349-356
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• 2006

At present, the selecting system and analytic estimation criterion on repair materials and methods of the deteriorated RC structures have not yet been set up in domestic. Under these circumstances, deterioration such as shrinkage crack, corrosion of rebar has been often occurred after repair, and this finally results in too frequent repairs. In this study, three types of repair methods were experimentally investigated by the accelerating test in a combined deterioration chamber and long-term field exposure test. Three types of repair methods applied in this study belong to a group of polymer cement mortar, which is commonly used in repair works. According to the results of this study, durability of repair mortar layers and corrosion properties of recovered rebar could be investigated in short period by the accelerating test in a combined deterioration chamber, which can simulate the condition of repeated high-and-low temperature and repeated dry-and-wet environment, spraying chloride solution and emitting $CO_2$ gas. After 36 month long-term filed exposure test in the coastal area, harmful macro-cracks are observed in the polymer cement mortar layer of some repair methods. These crack are considered to result from drying shrinkage of polymer cement mortar. Also, after 36 month exposure, amount of corrosion area and weight loss of rebar are found to be different according to the types of repair methods.

• Journal of Korean Foot and Ankle Society
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• v.15 no.2
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• pp.79-85
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• 2011

Purpose: The purpose of the present study was to compare and analyze the clinical outcomes of the percutaneous and open repair of acute Achilles tendon ruptures. Materials and Methods: We performed a retrospective study on 24 patients (group 1) managed with percutaneous repair, and 21 patients (group 2) managed with open repair for acute Achilles tendon rupture. The postoperative evaluations were done by an Arner-Lindholm scale and AOFAS score. Postoperative overall satisfaction and cosmetic satisfaction were also evaluated. Results: By Arner-Lindholm scale and AOFAS score, there was no difference between two groups (p<0.05). As for postoperative overall satisfaction, 5 cases were very satisfied, 16 cases were satisfied and 3 cases were fair in group 1. In group 2, 12 cases were very satisfied, 9 cases were satisfied. For postoperative cosmetic satisfaction, 13 cases were satisfied, 11 cases were fair in group 1. In group 2, 9 cases were very satisfied, 12 cases satisfied. In open repair group, a case of deep wound infection and three cases of skin necrosis were reported as complication. 2 cases of sural nerve injury were seen in percutaneous repair group and were recovered within 3 months. Conclusion: Percutaneous repair of acute Achilles tendon ruptures have high level of cosmetic satisfaction compared with open repair without any significant difference in clinical outcomes.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.553-560
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• 2020

In the existing research paper, we developed Mechanical Pressurizing Equipment(MPE) that can apply a certain amount of pressure and found out about improving the bonding strength of repair materials constructed in the repair section, and if pressurized, the bonding strength could be increased. In this study, the pressure of Mechanical Pressurizing Equipment(MPE) was changed to 0, 10, 30, 50, and 80 kPa, and the test was conducted to select effective pressure by measuring the flexural, compressive, and bonding strength of the specimens and deformation of the pressure plate at the age of 3 and 28th days. As a result of the test, 30 kPa was the most efficient pressure for the MPE. After producing the specimen with three types of repair materials with different main components, the bonding strength was measured according to dry and wet conditions, construction site (ceiling, wall and floor), and whether or not pressurized, on the 3rd, 7th, 14th, and 28th, indicating that the repair materials mixed with cellulose fiber was most effective for the MPE.

• Clinics in Shoulder and Elbow
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• v.9 no.1
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• pp.89-95
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• 2006

Purpose: Arthroscopic repair of rotator cuff tears are many techniques that have been developed to improve the initial postoperative strength of the repair. There was a doubt that current arthroscopic cuff repairs using a single row of suture anchors reproduce insufficient area of the anatomic cuff insertion, and concerns about failure of fixation often lead surgeons to limit early motion. Newer technique of double-row repair in arthroscopic treatment may provide initial stronger fixation and more contact with bone at the repair site than single-row repair did. We studied the comparison between clinical outcomes of arthroscopic single- and double-row repair in cuff tears at 1year postoperatively. Materials and methods: We retrospectively analyzed 40 shoulders with single-row repair and 38 shoulders with double-row repair of full-thickness rotator cuff tears between May 2002 and October 2004. Out of total 78 shoulders, 42 (54%) were male patients and 36 (46%) were female patients and the mean age at surgery was 56 years. All patients were diagnosed by physical examination and MRI. At 1year' follow-up after operation, we evaluated with the ASES and the Constant scoring system, and measured muscle power of abduction, internal and external rotation of the affected shoulder then compared with each other. Results: Mean ASES scores and Constant scores in double-row repair group improved more than single-row repair group significantly at 1year postoperatively. Muscle power of abduction and internal rotation, especially abduction power, improved more significantly in double-row repair group than in single-row repair. Conclusion: Arthroscopic double-row repair for the full thickness rotator cuff tear may be a superior technique, which showed better clinical outcomes and restoration of muscle power compared with single-row repair at relatively short period of postoperative follow-up. Restoration of footprint close to normal anatomy by double-row repair seems to play an important role in the recovery of muscle strength.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.89-96
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• 2018

Purpose: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bis-acryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. Materials and Methods: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. Results: The highest shear bond strength ($17.54{\pm}3.14MPa$) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. Conclusion: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.171-177
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• 2010

As concrete structures are exposed to chemical substances, damaged from salt, or progressed to the neutralization, the surface damage of the structures is generated timely fashion, resulting shortened service life. Especially, the sulfate erosion causes rapid surface defects, and the steel skeleton becomes corroded due to the water infiltration, generating stability deterioration of the concrete structure. In this study, the physical characteristics of the acid-resistant mortar with aluminosilicates was investigated in order to resolve problems of the acid resistance, one of the most serious problems of the cement type repair material. As the result of the experiment, the test specimen turned to exhibit almost equivalent physical characteristics with those of concrete sectional repair materials in terms of compressive and bending strengths. As both the cement sectional repair material and the test specimen were immerged in sulfuric acid solution to examine weight changes, the test specimens exhibited only 4% loss of their weights while the cement sectional repair materials reached at the level of 80% or above, proving the excellence acid resistant characteristics of the test specimens. Consequently, the physical characteristics of acid resistant mortar with aluminosilicates were revealed to be superior than those of concrete sectional repair materials. It can be utilized as a sectional repair material where the acidic erosion is anticipated.

• Architectural research
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• v.11 no.2
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• pp.27-34
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• 2009

The purpose of this study is to investigate the problem of crack repair materials and methods in existing concrete structure and to propose the effective injection method on crack repair by packer type. The result of this study is as follows. It is investigated that the crack width in the inner matrix of concrete structure is decreased about 30-40% than that in the surface of the concrete structure. Also it is showed that the possibility which could be monolithic with injection part became higher if the injection part is installed near to surface of concrete on the punching method to vertical direction against crack area. The injection of repair material can be poured smoothly under about $10N/mm^2$ pressure on the condition that cracks are monolithic with injection part without dust by drill. The method which is effective injection for a repair material is the punching method in compliance with coredrill. But, the research continuously is necessary about minimum injection pressure.

• Journal of Korean Foot and Ankle Society
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• v.6 no.1
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• pp.86-91
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• 2002

Purpose: This study was designed to evaluate whether the method "Distal pulling with wire" after primary repair of Achilles tendon, can result in early restoration of ankle motion. Materials and Methods: In 14 cases of tendocalcaneus repair, the proximal stump was pulled down distally by wire and fixed the ends of wire to the transcalcaneal K - wire. We evaluated the range of motion of ankle joint at 4th, 6th, 12th week in 10 patients whom we followed up for more than 1 year. We evaluated the results of Achilles tendon repair by Hooker's criteria. Results: Range of motion of ankle joint revealed as follows. Degree of mean dorsiflexion improved - $5.1^{\circ},\;15.0^{\circ},\;22.4^{\circ}$ at 4th, 6th and 12th week respectively, while plantarflexion improved $21.5^{\circ},\;32.7^{\circ}$ and $42.3^{\circ}$ respectively. At one year follow up, seven of them had no problems in active daily life and sports activities. According to Hooker's criteria, the result rated excellent in nine, satisfactory in one. Conclusion: Early gain of ankle joint motion was possible by "Distal pulling with wire" after primary repair of Achilles tendon.

• Journal of the Korea Institute of Building Construction
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• v.6 no.2 s.20
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• pp.91-98
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• 2006

The purpose of this study is to investigate the problem of crack repair materials and methods in existing concrete structure and to propose the effective injection method on crack repair by packer type. The result of this study is as follows. It is investigated that the crack width in the inner matrix of concrete structure is decreased about 30-40% than that in the sulfate of the concrete structure. Also it is showed that the possibility which could be monolithic with injection part became higher if the injection part if installed near to surface of concrete on the punching method to vertical direction against crack area. The injection of repair material can be poured smoothly under about $10N/mm^2$ pressure on the condition that cracks are monolithic with injection part without dust by drill. The effective method to pour the injection repair material is the punching method by coredrill but several research to minimize injection pressure should be continually.

• Steel and Composite Structures
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• v.32 no.1
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• pp.127-139
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• 2019

Bridges, offshore oil platforms and other infrastructures usually require at some point in their service life rehabilitation for reasons such as aging and corrosion. This study explores the application of adhesively bonded CFRP patches in repair of corroded circular hollow sectional (CHS) steel beams. An experimental program involving three-point bending tests was conducted on intact, corroded, and repaired CHS beams. Meso-scale finite element (FE) models of the tested beams were developed and validated by the experimental results. A parametric study using the validated FE models was performed to examine the effects of different CFRP patch parameters, including patch dimensions, number of plies and stacking sequence, on efficiency of the repair system. Results indicates that the corrosion reduced elastic stiffness and flexural strength of the undamaged beam by 8.9 and 15.1%, respectively, and composite repair recovered 10.7 and 18.9% of those, respectively, compared to undamaged beam. These findings demonstrated the ability of CFRP patch repair to restore full bending capacity of the corroded CHS steel beam. The parametric study revealed that strength and stiffness of the repaired CHS beam can be enhanced by changing the fiber orientations of wet composite patch without increasing the quantity of repair materials.