• 대한건축학회논문집:구조계
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• 제34권2호
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• pp.41-48
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• 2018

Carbonation is one of the major detrimental factors to the reinforced concrete structures owing to penetration of atmospheric CO2 through the micro pores, thereby it reduces the durability of the concrete. The maintenance periods and cost for concrete according to the coefficient variation of different finishing materials is documented in literature. However, it is required to carry out the systematic and well planned studies. Therefore, keeping them in mind, surface repair was carried out to the carbonated concrete and the maintenance cost was calculated to measure the durability life after repair with different variable. The deterministic and probabilistic methods were applied for durability and repair cost of the concrete. In the existing deterministic model, the cost of repair materials increases significantly when the concrete structure reaches its service life. In present study using a stochastic model, the maintenance period and cost was evaluated. According to obtained results, there was no significant difference in the number of maintenance of the coefficient variation. The initial durability has a great influence on the maintenance time and cost of the structure. Unlike the deterministic model, the probabilistic cost estimating model reduces the number of maintenance to the target service life expectancy.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.1-9
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• 2004

Repair of concrete structures has been a focus of attention in recent years not only in Japan but also worldwide. Concrete structures have fallen short of expectations at the time of construction-they should have been perpetual and maintenance-free. However, investigation into their premature deterioration reveals the primary causes: Concrete was made using inadequate materials and/or inadequate mixture proportions due to insufficient consideration and was placed inadequately under insufficient execution control. The secondary causes include insufficient consideration at the time of construction for the environmental conditions to which the structures were to be exposed. In any event, in the current economic climate, structures cannot be demolished and rebuilt as soon as they are damaged, but instead are expected to continue to be in service as long as possible with appropriate repair or retrofitting. This paper analyzes the causes of deterioration requiring repair and introduces relevant repair techniques. At the end, the repair project of the Sanyo Shinkansen Line in which the author was involved through committee activities is reported.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.207-211
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• 2006

This paper presents an experimental study on the repair performance of sprayed engineered cementitious composites(ECC) serving as a repair material. Sprayable ECC, which exhibit tensile strain-hardening behavior in the hardened state and maintain sprayable properties in the fresh state, have been developed by using a parallel control of micromechanical design and rheological process design. The effectiveness of sprayable ECC in providing durable repaired structures was assessed by spraying the ECC and testing them for the assessment. The experimental results revealed that, when sprayed ECC were used as a repair material, both load carrying capacity and ductility represented by the deformation capacity at peak load of the repaired flexural beams were obviously increased compared to those of commercial prepackaged mortar(PM) repaired beams. The significant enhancement in the energy absorption capacity and tight crack width control of the ECC repair system treated with wet-mix spraying process suggests that sprayed ECC can be effective in extending the service life of rehabilitated infrastructures.

• 건축역사연구
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• 제29권6호
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• pp.89-100
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• 2020

This paper sought to examine characteristics and differences of the construction methods and the materials of the wall repair by three command through individual command records and national documents. This paper is based on the management section of three commands(Samgunyoung), which was in charge of a repair and management of Hanyangdoseong(Seoul city wall) in 18th century. The purpose and background of the study are as follows. First, through each inscribed stones on the rampart and the parapet, it is to grasp accurately the point of change of Hanyangdoseng after the 18th century. Second, through inscribed stones, the site evidence of the repair work in the late Joseon Dynasty, it is to find out the aspects of the development process of repair and reconstruction technology of Hanyangdoseng.

• Journal of Chest Surgery
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• 제45권6호
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• pp.390-395
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• 2012

Background: Conventional open repair is a suboptimal therapy for blunt traumatic aortic injury (BTAI) due to the high postoperative mortality and morbidity rates. Recent advances in the thoracic endovascular repair technique may improve outcomes so that it becomes an attractive therapeutic option. Materials and Methods: From August 2003 to March 2012, 21 patients (mean age, 45.81 years) with BTAI were admitted to our institution. Of these, 18 cases (open repair in 11 patients and endovascular repair in 7 patients) were retrospectively reviewed and the early perioperative results of the two groups were compared. Results: Although not statistically significant, there was a trend toward the reduction of mortality in the endovascular repair group (18.2% vs. 0%). There were no cases of paraplegia or endoleak. Statistically significant reductions in heparin dosage, blood loss, and transfusion amounts during the operations and in procedure duration were observed. Conclusion: Compared with open repair, endovascular repair can be performed with favorable mortality and morbidity rates. However, relatively younger patients who have acute aortic arch angulation and a small aortic diameter may be a therapeutic challenge. Improvements in graft design, delivery sheaths, and graft durability are the cornerstone of successful endovascular repair.

• 헤리티지:역사와 과학
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• 제53권2호
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• pp.140-155
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• 2020

본 연구는 강진 무위사 극락보전의 수리 자료, 행정 문서 등의 분석을 통해 시기별 벽체 수리 내용을 살펴보고, 건물에 설치된 벽체의 재료와 시공기술이 어떠한 차이점 및 공통점을 갖는지 살펴보는 것을 목적으로 한다. 해체 수리 시기는 1935년, 1956년, 1982~3년 이뤄진 수리를 대상으로 그 전후 시기의 과정을 함께 분석하였으며, 연구를 통해 도출한 결과는 다음과 같다. 첫째, 1935년 해체 수리 시 진행된 벽체공사에서 외엮기는 원래의 것을 준수하고, 초벽·재벌·정벌은 기존과 다른 재료가 사용된 것을 확인하였다. 벽체의 구성 재료에는 초벽은 점토, 석회, 강사, 재벌은 모래, 회반죽, 정벌은 회반죽과 해초풀이 사용되었다. 둘째, 1956년 수리 시 확인한 벽체의 외엮기 구성 방식은 껍질째 가는 잡목을 가로·세로외로 사용하였고, 새끼줄을 이용해 대각선으로 엮는 방법으로 설치된 것을 확인하였다. 또한, 측면 벽체 훼손 상태를 통해 벽선과 유사 크기의 중깃이 상·하인방에 결구된 방식임을 확인하였다. 셋째, 1982~3년 수리공사에서는 외엮기 방식은 재래의 수법을 따른다고 하였고, 직접 피운 생석회(소석회)와 모래, 황토, 여물, 해초풀을 섞어 회사벽을 구성하였다. 넷째, 시기별 수리공사 내용을 종합하였을 때, 외엮기 방식은 1900년 이전의 방식이 명확하였으며, 초벽에 사용된 재료는 1935년 이후 재료의 변화가 있었다. 다섯째, 수리별 사용되는 재료는 달라졌지만, 각 공사마다 유의할 점에 대해 표기한 부분에서 문화재 수리 원칙에 대한 공통적인 견해를 갖고 있는 것으로 볼 수 있다.

• 대한건축학회논문집:구조계
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• 제34권9호
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• pp.19-26
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• 2018

The focus of this study was centered around 15 common injection type water leakage repair materials (3 different types for each; synthetic polymer, cementitious, acrylic, epoxy, urethane) used in concrete structures of Korea and analyzing their wet surface adhesion performance in accordance to the ISO TS 16774 Test Method for Repair Materials for Water-leakage Cracks in Underground Concrete Structures, Part 4: Test Method for Adhesion on Wet Concrete Surface, and the results of this study was taken to be place under a comparative analysis with the results of the preceeding study on response to substrate movement performance study. The results of this comparative study showed that other than 1 specimen of 1 type of the acrylic and 3 specimens of 1 type of the synthetic polymer type materials, all of the 93% of the specimens used in this study showed stable adhesion on wet substrate surface, and we were able to determine that materials that have proper response properties against substrate movement are highly flexible and have high adhesion properties, but their adhesion properties on wet substrate would change based on their viscosity.

• 문화기술의 융합
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• 제6권1호
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• pp.477-483
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• 2020

콘크리트 박스 구조물이 열화되어 보수보강이 필요할 경우 스프레이 장비로 구조물 단면에 보수재를 분사하여 부착시키는 방법에 의존하고 있는데 천장 또는 벽체부위의 경우 시공 후 보수재 자중 또는 중력에 의해 부착력이 저하될 수 있으며 지하철 구조물의 경우 진동 등에 의해 초기 부착력이 떨어지는 문제점이 발생한다. 또한 작업자의 숙련도와 시공환경에 따라 보수품질이 변동되기에 이에 대한 보완책이 필요한 실정이다. 본 연구에서는 중력에 의한 보수재의 부착력 저하 및 인력시공에 의한 보수품질의 변동과 같은 문제점을 해결하고자 보수재 시공 후 소정의 압력을 가할 수 있는 기계식 가압장비를 개발하였다. 그리고 가압장비의 성능을 알아보고자 현장조건을 모사할 수 있는 챔버를 제작하여 가압 유무, 단면부위 및 환경조건을 달리한 부착강도를 측정한 결과 가압할 경우 그렇지 않은 경우보다 부위별로 차이가 있었으나 최대 70% 부착강도가 증가하는 효과를 얻을 수 있었다.

• Archives of Plastic Surgery
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• 제46권3호
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• pp.228-234
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• 2019

Background The management of flexor tendon injuries has evolved in recent years through industrial improvements in suture materials, refinements of repair methods, and early rehabilitation protocols. However, there is no consensus on the ideal suture material and technique. This study was conducted to compare the tensile strength, repair time, and characteristics of 4-strand cruciate, modified Kessler, and 4-strand horizontal intrafiber barbed sutures for flexor tenorrhaphy with a 12-mm suture purchase length in an animal model. Methods The right third deep flexors of 60 adult Leghorn chicken feet were isolated and repaired with a 12-mm suture purchase length. The tendons were randomly assigned to three groups of equal number (n=20 each). Groups 1 and 2 received 4-strand cruciate and modified Kessler repair with conventional suture materials, respectively. A 4-strand horizontal intrafiber barbed suture technique was used in group 3. The repaired tendons were biomechanically tested for tensile strength, 2-mm gap resistance, and mode of failure. Repair times were also recorded. Results The maximum tensile strength until failure was $44.6{\pm}4.3N$ in group 1, $35.7{\pm}5.2N$ in group 2, and $56.7{\pm}17.3N$ in group 3. The barbed sutures were superior to the other sutures in terms of the load needed for 2-mm gap formation (P<0.05). Furthermore, the barbed sutures showed the shortest repair time (P<0.05). Conclusions This study found that 4-strand horizontal intrafiber barbed suture repair with a 12-mm purchase length in a chicken flexor tendon injury model showed promising biomechanical properties and took less time to perform than other options.

• Corrosion Science and Technology
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• 제7권1호
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• pp.6-12
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• 2008

Non-metallic composite overwrap repair methods utilize resin based fiber-reinforced composite materials, which have higher specific strength to weight ratio and stiffness, superior corrosion and fatigue resistance, and substantially reduced weight when compared to carbon steel. Non-metallic repair methods/systems can allow desired functional properties to be achieved at a respectable economic advantage. For example, non-metallic composite repair systems have at least a 50 year design stress of 20 ksi and approximately 25% of the short term tensile strength of fiberglass. For these systems, the contribution of the repaired steel to the load carrying capability need not be considered, as the strength of the repair itself is sufficient to carry the internal pressure. Worldwide experience in the Oil & Gas industry confirms the integrity, durability, inherent permanency, and cost-effectiveness of non-metallic composite repair or rehabilitation systems. A case study of a recent application of a composite repair system in Saudi Aramco resulted in savings of 37% for offshore subsea line and 75% for onshore above grade pipeline job. Maintaining a pipeline can be costly but it is very small in comparison to the cost of a failure. Pipeline proponents must balance maintenance costs with pipeline integrity. The purpose is not just to save money but also to attain a level of safety that is acceptable. This technology involves the use of an epoxy polymer resin based, fiber-reinforced composite sleeve system for rehabilitation and /or repair pipelines.