• 한국안전학회지
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• 제28권5호
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• pp.21-26
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• 2013

Delamination of cover concrete due to re-bar corrosion is a critical damage reducing structural safety of reinforced concrete structures. Therefore, it should be detected and evaluated to provide appropriate maintenance to recover structural integrity. Impact-echo method, which utilizes thickness vibration characteristics of delaminated concrete section, is effective for detection and evaluation of small areal size delamination. However, it may not be applicable for large areal size delamination in which flexural vibration modes are dominated. In this study, applicability of vibration mode shapes of delaminated concrete section is investigated for visualization of delamination region in concrete structures. Numerical and experimental modal tests are performed to estimate mode shapes of delaminated concrete section and linear absolute summation technique is proposed for effective visualization of delamination region based on estimated mode shapes.

• 한국전산구조공학회논문집
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• 제28권1호
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• pp.47-51
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• 2015

본 논문에서는 복합재 구조물에 손상이 있을 경우, 손상에 의해 변화된 구조물의 동적특성을 손상이 없는 상태로 회복하여, 전체 시스템의 안정성을 유지할 수 있도록 하였다. 층간 분리가 있는 구조물의 유한요소모델 구축을 위하여 향상된 층간 변위장 모델을 적용하였으며, 유한요소해석을 진행하여 구조물의 고유 진동수와 모드 형상을 관찰하였다. 능동제어 알고리즘과 압전 작동기를 적용하여 구조물의 진동 응답특성을 확인하였으며, 이를 바탕으로 손상된 구조물의 동적특성을 손상이 없는 상태로 회복할 수 있음을 확인하였다.

• Clinics in Shoulder and Elbow
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• 제19권4호
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• pp.197-201
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• 2016

Background: The purpose of the study was to compare the degree of degeneration of the articular and bursal layers of delaminated supraspinatus tendons based on histological examination. Methods: Fifty-four patients with a full-thickness rotator cuff tear were included in the study. Tendon specimens were harvested during arthroscopic rotator cuff repair from the lateral torn edges of the articular and bursal layers of the delaminated tear. Harvested samples were stained with H&E dye and evaluated based on a semi-quantitative grading scale. Results: There were no significant differences in the seven histological characteristics of tendon degeneration: fiber structure, fiber arrangement, round nuclei, regional variations in cellularity, vascularity, collagen stainability, and hyalinization between the articular and bursal layers of the delaminated rotator cuff tear (all p>0.05). Total degeneration scores of articular and bursal sides were $13.1{\pm}3.85$ points and $13.2{\pm}3.42$ points, respectively, and were not significantly different (p=0.958). Conclusions: The study demonstrates that tendon degeneration was similar in the articular and bursal sides of the delaminated full-thickness rotator cuff tear, suggesting that degeneration would be a main etiology for the rotator cuff tear not only in the articular side but also in the bursal side. Considering potential disadvantages of subacromial decompression, this study tentatively suggests routine use of subacromial decompression as well as the need for halting or recovery from rotator cuff degeneration for better rotator cuff repair.

• 대한정형외과스포츠의학회지
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• 제10권2호
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• pp.61-68
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• 2011

목적: 전층 회전근 개 파열의 관절경하 봉합술 시 관찰되는 회전근 개 판분리 현상의 유무에 따른 술 후 임상적 결과에 대해 보고하고자 한다. 대상 및 방법: 2006년 3월부터 2008년 10월까지 회전근 개 전층 파열로 관절경하 이열 봉합술을 시행한 48예(남자 31, 여자 17, 평균나이 57.6세, 범위 45~68세)를 대상으로 하였다. 평균 파열 크기는 2.8 cm(범위: 1.2~3.6 cm) 이었고 판분리 유무에 따라 봉합법을 달리하여 판분리가 있는 경우 점액낭 층과 관절면 층을 각각 구분하여 봉합하였다. 술 후 평균 추시 기간은 26개월(범위: 18~33)이었으며 American Shoulder and Elbow Surgeons (ASES), University of California at Los Angeles (UCLA) 점수와 등속성 근력 평가를 이용하여 기능적 결과를 판정하였고 술 후 평균 8개월(범위: 6~13)에 촬영한 자기 공명 영상을 이용하여 봉합부의 해부학적 연속성을 판정하였다. 관절경하에서 관찰된 판분리 현상의 양상과 나이, 성별, 이환 기간, 파열의 크기, 술 후 만족도, 재 파열 빈도와의 상관 관계를 판정하였다. 결과: 술 후 44예(91.7%)에서 견관절의 기능적 호전을 보였다. 관절경 소견 상 48예 중 15예에서 회전근 개의 판분리(31%)가 관찰되었으며 대부분 내측과 후내방으로 퇴축되어 있었고 분리된 두 층 중 관절면 층이 더 두꺼운 경우가 8예(53%), 점액낭층보다 근위부 및 후내방으로 전위된 경우가 9예(60%)이었다. 최종 추시 상의 기능적 점수는 판분리 현상의 유무와 상관 관계를 보이지 않았으며 성별, 이환 기간, 술 전 파열의 크기, 술 후 만족도는 판분리 현상과 상관 관계가 없었으나 고령일수록 판분리 현상이 더 많이 관찰되었다(p=0.041). 술 후 촬영한 29예의 자기 공명 영상 소견 상 완전치유가 14예(48%), 부분치유가 9예(31%)이였으며 6예(21%)에서 봉합부의 완전 재파열이 발생하였으나 이 중 50%는 임상적 결과가 양호로 판정되었다. 추시 자기 공명 영상 상 판분리 현상이 없는 경우에서는 79%(15/19), 판분리 현상이 있는 경우는 80%(8/10)에서 봉합부가 치유된 것으로 판정되어 판분리 현상이 있는 경우의 복층 이열봉합술은 판분리 현상이 없는 경우의 단층 이열봉합술과 유사한 봉합부의 해부학적 연속성이 관찰되었다(p=0.165). 결론: 관절경하 회전근 개 봉합 시 판분리 현상은 본 연구에서 약 31%이였으며 이는 고령에서 더 흔히 관찰되었다. 성별, 이환기간, 술 전 파열의 크기, 기능적 결과 및 술 후 만족도에 있어 판분리 파열의 영향은 없었으며 봉합부의 해부학적 연속성도 판분리 현상이 없는 회전근 개 파열과 유사한 결과를 보였다.

• 한국안전학회지
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• 제28권6호
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• pp.36-41
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• 2013

Previous study showed that delamination region in concrete structures can be successfully visualized using mode shapes of delaminated concrete section. However, modal tests for this purpose to obtain mode shapes of the delaminated concrete section may not be applicable in practice since, to correctly obtain the mode shapes of the section, the location and the shape of the delamination region in a structure should be known in advance. Unfortunately those are normally unknown in a real structure. Therefore, a moving forward test method may be useful to obtain the mode shapes of the concrete section when the location and the shape of the delamination region are not known. In this study, impact-echo testing based mode shape estimation technique is proposed and experimentally validated for visualization of delamination region.

• Structural Engineering and Mechanics
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• 제4권3호
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• pp.243-255
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• 1996

This paper presents a model of a layered, delaminated composite beam. The beam is modelled by beam finite elements, and the delamination is modelled by additional boundary conditions. In the present study, the laminated beam contains only one delaminated region through the thickness direction which extends to the full width of the beam. It is also assumed that the delamination is open. The influence of the delamination length and position upon changes in the bending natural frequencies of the composite laminated cantilever beam is investigated.

• 한국소음진동공학회논문집
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• 제15권4호
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• pp.395-403
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• 2005

The dynamic characteristics of delaminated smart composite laminates are studied using animproved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all free surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.

• 대한견주관절학회:학술대회논문집
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• 대한견주관절학회 2009년도 제17차 학술대회
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• pp.210-210
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• 2009

For a bursal-side retracted laminated rotator cuff tear, simple repair of the retracted bursal-side rotator cuff might be insufficient because the repaired tendon could remain as an intratendinous tear of the rotator cuff. We present a repair method for intratendinous rotator cuff tears using the suture-bridge technique. We believe that this method helps to preserve the remnant rotator cuff tendon without tissue damage and restores the normal rotator cuff footprint in bursal-side delaminated rotator cuff tears.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.83-89
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• 2000

Dynamic characteristics of multi-delaminated composite beams are presented in this work. In order to investigate the effects of sizes, locations and types of delaminations on composite beams, the general kinematic governing equations are derived and solved by dividing the delaminated beam and imposing the continuity conditions into each sub-beam The results show dynamic behaviors are varied according to the sizes, types and locations of delaminations through the laminated composite beams. It is shown that the effects of delaminations on the dynamic characteristics of composite beams could be used to detect their sizes, types and locations from the results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.469-475
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• 2004

The transient analysis of delaminated smart composite laminates is studied using an improved layerwise laminate theory. The theory is capable of capturing interlaminar shear stresses that are critical to delamination. The presence of discrete delamination is modeled through the use of Heaviside unit step functions. Stress free boundary conditions are enforced at all fee surfaces. Continuity in displacement field and transverse shear stresses are enforced at each ply level. In modeling piezoelectric composite plates, a coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. Numerical analysis is conducted to investigate the effect of nonlinearity in the transient vibration of bimodular behavior caused by the contact impact of delaminated interfaces. Composite plates with delamination, subject to external loads and voltage history from surface bonded sensors, are investigated and the results are compared with corresponding experimental results and plates without delamination.