• International Journal of Reliability and Applications
• /
• 제11권2호
• /
• pp.123-138
• /
• 2010

This paper investigates a mathematical model of a system composed of two non-identical unit parallel system with common-cause failure, critical human error, non-critical human error, preventive maintenance and two type of repair, i.e. cheaper and costlier. This system goes for preventive maintenance at random epochs. We assume that the failure, repair and maintenance times are independent random variables. The failure rates, repair rates and preventive maintenance rate are constant for each unit. The system is analyzed by using the graphical evaluation and review technique (GERT) to obtain various related measures and we study the effect of the preventive maintenance preventive maintenance on the system performance. Certain important results have been derived as special cases. The plots for the mean time to system failure and the steady-state availability A(${\infty}$) of the system are drawn for different parametric values.

• Clinics in Shoulder and Elbow
• /
• 제25권4호
• /
• pp.334-338
• /
• 2022

Currently, the literature contains few studies that describe any potential complications following arthroscopic acromioplasty. Because part of the anterior deltoid originates from the anterior acromion, there is a risk for violation and subsequent iatrogenic rupture or avulsion during this procedure. This type of injury can be a devastating problem for patients that may lead to poor function and debilitating pain. We present a patient with deltoid insufficiency following arthroscopic acromioplasty who elected to proceed with operative management with a planned arthroscopic evaluation of the shoulder followed by an open deltoid repair. At the final follow-up visit 2.5 years postoperatively, the patient reported improved pain from baseline and no residual disability and was able to perform most activities of daily living without difficulty. This case serves as an example of a surgical repair for a deltoid avulsion following arthroscopic acromioplasty. As there is still a lack of standard guidelines, our suture repair technique can be considered one method of treatment for this type of injury.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2020년도 봄 학술논문 발표대회
• /
• pp.81-82
• /
• 2020

In this study, after applying a silicate-based impregnation and polymer-based coating to fire damaged high strength concrete, carbonation resistance was evaluated to compare and evaluate the carbonation depth according to the type of surface repair materials. As a result of the experiment, it was confirmed that the carbonation resistance was increased in the case of the concrete with the surface repair materials compared to the control specimen without the surface repair materials. In particular, in the case of the polymer-based coating agent, it was confirmed that the carbonation hardly progressed.

• 항공우주시스템공학회지
• /
• 제7권1호
• /
• pp.39-43
• /
• 2013

In this study, damage assesment and repair technique of aircraft adopted on Sandwich composite structure were performed. The sandwich composite structure were damaged by drop weight type impact test machine. The damaged sandwich composite structure was repaired using external patch repair method after removing damaged area. This study presents comparison results of the experimental investigation between the impact damaged and the repaired specimen.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2022년도 가을 학술논문 발표대회
• /
• pp.159-160
• /
• 2022

The purpose of this study is to evaluate the adhesion in flexure depending on the cement type, polymer type, polymer-cement ratio, and silica fume ratio of the polymer-cement composites(PCCs) for crack repair in RC structures to induce optimal mix proportions. The adhesion in flexure of PCCs for crack repair of RC structure has a significant effect on the polymer type and polymer-cement ratio, and the adhesion in flexure is generally improved with mixing of silica fume as a mixture. The adhesion in flexure according to the type of polymer is slightly higher in the order of SAE, EVA, and SBR, and it is relatively high at the polymer-cement ratio of 60% or 80%. In addition, the adhesion in flexure of PCCs with silica fume ratio of 10% or 20% to the cement weight is higher than that without silica fume. In order to improve the adhesion in flexure of PCCs for repairing cracks in RC structures, the optimal mix design is to properly adjust the cement type, polymer type, polymer-cement ratio, and silica fume ratio.

• Composites Research
• /
• 제18권4호
• /
• pp.66-74
• /
• 2005

This paper reports new repair and strengthening mathod using improved material. This mathod have two type according to covering thickness of reinforcement. One type is near surface mounted FRP rod. Anther type is overay. Fiber Reinforced Plastic (FRP) materials has become very popular in recent years. FRP material used to rehabilitate many types of structures with superior characteristics such as high strength and stiffness and corrosion resistance. This strengthening mathod were used FRP rod which have better bond and shear strangth than current FRP rod. Development of FRP rod due to 3-D winding system. In addition, Ductile hybrid FRP has a certain plastic deformation and an elongation greater than 3% at maximum load is usually required for steel reinforcement in concrete structures. Moerover this mathod can be effective repair of base concrete by sprayed polymer mortar.

• Restorative Dentistry and Endodontics
• /
• 제21권1호
• /
• pp.35-53
• /
• 1996

The development and repair requires the formation of new tissues comprised of various extracellular matrix components. The present study investigated the formation and distribution of the major ECM components such as type I collagen, type III collagen, fibronection, bone sialoprotein, and osteonection during development and repair. For developing observation. Sprague-Dawley rats weighing $27{\pm}1gm$ were sacrificed. For repair observation, Sprague-Dawley rats weighing $110{\pm}5gm$ were used. The pulp perforation were prepared on mesial surface of the maxillary first molar by using 1/2round bur. At 5 days after perforation, rats were sacrificed by perfusion with 3 % paroformaldehyde. The maxillary first molar region were cut, demineralized, dehydrated and embedded in paraffin. Immunostaining the ECM components was achieved by the avidin-biotin complex method. The results as follows : 1. Bright immunoreaction for fibronectin was present in the basement membrane at the inner epithelial-mesenchymal interface, especially concentrated in the blood vessel walls, cell membrane of odontoblasts, and initial predentin. 2. Type I and III collagen was observed in the newly formed pulp tissue, predentin, and its intensity increased as more of these components during repair. 3. Strong immunostaining for bone sialoprotein and osteonectin was found in dentin while no or weaker staining was observed loose connective tissue of the pulp. 4. These results suggest that develpment and repair is achieved through a series of cell differentiation and attachment by the specific ECM components.

• Clinics in Shoulder and Elbow
• /
• 제10권1호
• /
• pp.73-77
• /
• 2007

목적: 견관절의 제 2형 SLAP 병변에 대하여 흡수성 봉합 나사못을 이용하여 관절경적 봉합을 시행한 후 임상적 결과를 보고하고자 한다. 대상 및 방법: 이 연구에는 25명에 대한 25례(남자가 20명, 여자가 5명)가 포함되었다. 평균 연령은 44.5세였다. 수술 전 ASES 점수는 평균 44점이었다. 모든 예에서 SLAP 병변을 관절경적으로 1개 또는 2개의 흡수성 봉합 나사못을 사용하여 수술을 시행하였다. 평균 추시 기간은 15개월이었다. 결과: 최종 추시시 ASES 점수는 평균 92.7점으로 향상되었으며 견관절의 운동 범위는 23례에서 완전한 회복을 보였으나 2례에서 경미한 운동범위 제한이 있었으나 일상 생활에는 문제가 없었다. 결론: 제 2형 SLAP 병변에 대하여 흡수성 봉합 나사못을 이용한 관절경적 봉합 수술이 만족할 만한 임상적 결과의 소견을 보여 매우 좋은 수술 방법으로 사료된다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제21권5호
• /
• pp.148-155
• /
• 2017

본 연구에서는 지하 콘크리트 구조물의 누수 균열에 사용되는 주입형 누수보수재료의 품질관리 방안으로 규격화된 국제표준 ISO TS 16774, Part 2 Test method for chemical resistance를 이용하여 현재 우리나라 누수보수현장에서 사용하고 있는 주입형 누수보수재료 2계열(합성고무계, 시멘트계), 3종류 씩, 총 9 종류의 보수재료에 대한 지하 콘크리트 구조물이 처한 화학적 환경의 저항 안정성을 연구 검토하였다. 그 결과, 합성고무계는 RG-3를 제외하고, 산에 대한 저항력을 높일 수 있는 재료적 검토가 필요하고, 시멘트계는 수산화나트륨, 염화나트륨에 대한 저항을 높일 수 있는 재료적 검토의 필요성이 확인되었다. 이러한 결과는 콘크리트 구조물의 화학적 환경에서의 보수재료 선정 시 기본 지표로 사용가능 할 것으로 판단된다. 또한, 추후에 연구 개발 되는 보수재료의 품질 향상에 반영할 수 있는 기준 자료의 활용을 기대할 수 있다.

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