• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.686-694
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• 2010

Continuing progress in high technology has created numerous industrial applications for new advanced composite materials. Among these materials, carbon fiber-reinforced plastic (CFRP) laminate composite is typically used for low-weight carrying structures that require high specific strength. In this study, the damage mechanism of a compact tension (CT) specimen of woven CFRP laminates is described in terms of strain and displacement changes and crack growth behavior. The digital image correlation (DIC) method (which is employed here as a computer vision technique) is analyzed. Acoustic emission (AE) characteristics are also acquired during fracture tests. The results demonstrate the usefulness of these methods in evaluating the damage mechanism for woven CFRP laminate composites. From the results, we show these methods are so useful in order to evaluate the damage mechanism for woven CFRP laminate composites.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.907-910
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• 2010

This study has developed a numerical analysis technique newly which can evaluate the damage propagation characteristics of civil infrastructures. To do this, numerical techniques are incorporated for the concrete members up to the compressive damage due to the bending compressive forces after the tensile crack based on the deformation mechanism. Especially, for the compressive damage stage after the tensile crack, the crack propagation process will be analyzed numerically using the concept of an equivalent plastic hinged length. Using this concept, we investigate the reasonability of the developed module by comparing commercial program for the tunnel structure. It can be established from this study that section forces, such as axial forces and the moment cracks takes place, can be related to the width of the crack making it possible to analyze the crack extension.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.301-320
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• 2009

Damage assessment for buried structures against an internal blast is conducted by considering the soil-structure interaction. The structural element under analysis is assumed to be rigid-plastic and simply-supported at both ends. Shear failure, bending failure and combined failure modes are included based on five possible transverse velocity profiles. The maximum deflections with respect to shear and bending failure are derived respectively by employing proper failure criteria of the structural element. Pressure-Impulse diagrams to assess damage of the buried structures are subsequently developed. Comparisons have been done to evaluate the influences of the soil-structure interaction and the shear-to-bending strength ratio of the structural element. A case study for a buried reinforced concrete structure has been conducted to show the applicability of the proposed damage assessment method.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.295-300
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• 2002

To establish an optimum condition in the surface treatment and curing process will be an important parameters for the fabrication of multilayered hybrid composite materials, A17075/CFRP (CARALL : carbon fiber reinforce aluminum laminates). Effects of carbon fiber direction and thickness variation in tensile strength were investigated. And impact damage behavior of carbon fiber reinforce plastic (CFRP) and CARALL were investigated also, it was found that a partial stress increase in order of epoxy adhesive, A17075, CFRP. And the partial stress of CFRP carried out a great portion of applied stress. The impact damage resistance of CARALL was higher than that of CFRP. This is because both side Al sheet of CARALL absorb a great of impact damage.

• 한국안전학회지
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• 제19권2호
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• pp.112-118
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• 2004

Recently, when being constructed the large structures, the deep excavations have performed to utilize the underground space. As the ground excavation is deeper, the damage of the adjacent structure and the ground is frequently occurred. the Analysis of the retaining structures is necessary to safety of the excavation works. There are many methods such as elasto-plastic theory, FEM, and FDM to analyze the displacement of the retaining structure. In this thesis, GEBA-1 program by the Nakamura-Nakajawa elasto-plastic method was developed. The lateral displacement of the wall was analyzed by the developed program GEBA-1, SUNEX, and EXCAD, and compared with the measured displacement bye the Inclinometer. The monitored fields were three excavation work site in S-I, S-II, and S-III area. Excavation method of each site is braced retaining wall using H-pile. Excavation depth is 14m, 14m, and 8.2m.

• 한국정밀공학회지
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• 제15권1호
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• pp.43-50
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• 1998

The purpose of the paper is to protect the damage of plastic IC package with searching the cause of the fracture due to the delamination and crack when the encapsulant of plastic IC package is on viscoelastic behavior with the effect of creep on high temperature, The model for analysis is the plastic SOJ package with dimpled diepad in the IR soldering process of surface mounting technology. The risk of delamination with calculating the distribution of viscoelastic thermal stress in the package without the crack in the surface mounting process is checked. The package model with the perfect delamination between chip and diepad is chosen to estimate the resistance against fracture in thermal loading with calculating C (t)-integrals according to the change of the design. The optimum design to depress the delamination and crack is presented.

• Archives of Plastic Surgery
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• 제40권3호
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• pp.247-250
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• 2013

Circumcision is one of the most common rituals in Jewish and Islamic cultures. It may also be performed for phimosis correction or the treatment of recurrent balanitis. Although circumcision is considered to be a technically easy and safe surgical procedure with no significant risk, it may lead to severe complications such as necrotizing fasciitis or total penis amputation. In this report, we present a case of penis amputation at two levels occurring with third-degree burns due to electrocautery during circumcision. Although penile replantation was attempted, it was unsuccessful due to burn damage to the veins. After restoration of the functional structures, the penis was buried in the inguinal area by reepithelization to maintain blood circulation. The recovery of the penis was successful. This case is presented as a novel example of groin flap surgery to achieve a functionally and aesthetically acceptable outcome in a salvage operation for a penis with significant traumatic injury, which has not been previously reported in the literature.

• Geomechanics and Engineering
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• 제21권6호
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• pp.527-536
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• 2020

An elastic-plastic solution for cavity expansion problem considering strength degradation, undrained condition and initial anisotropic in-situ stress is established based on the Tresca yield criterion and cavity expansion theory. Assumptions of large-strain for plastic region and small-strain for elastic region are adopted, respectively. The initial in-situ stress state of natural soil mass may be anisotropic caused by consolidation history, and the strength degradation of soil mass is caused by structural damage of soil mass in the process of loading analysis (cavity expansion process). Finally, the published solutions are conducted to verify the suitability of this elastic-plastic solution, and the parametric studies are investigated in order to the significance of this study for in-situ soil test.

• 한국응용곤충학회지
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• 제31권2호
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• pp.174-181
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• 1992

씨고자리파리(Delia platura) 유충의 피해가 차후 대두 생육과 생산성에 미치는 영향을 기상생태형별로 조사하고 또 해충종합관리의 방안으로서 토양내 유기물함량, 토양의 종류, 피복등과 피해정도와의 관계를 분석한 결과를 종합해 보면 다음과 같다. 콩 초생단엽의 피해로 영양생장이 지연되었는데 일장에 의해 유도되는 개화기에는 큰 변화가 없었다. 인위적으로 적엽한 구 보다는 충접종에 의한 피해구에서 생육지연 현상이 두드러졌는데 이는 초생단엽 피해 외에 지하 경.근부가 함께 피해를 받은 때문이었다. 생산량은 초생단엽이 25% 피해를 받은 구부터 크게 감소하였다. 콩의 출현속도는 무피복구에 비해 피복구에서 빨랐는데 투명비닐의 촉진 효과가 가장컸다. 식양토와 식토구에서 재배한 콩의 피해가 적었으며 토양내 부엽토 함량이 증가하면 출현속도가 빨라져 초생단엽의 피해가 감소하는 것으로 나타났다.

• Composites Research
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• 제36권1호
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• pp.59-67
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• 2023

항공우주산업에서 경량화를 위해 사용되는 CFRP 복합재료로 구성된 차체의 충격에 따른 파손은 탑승자의 안전과 직결된다. 따라서 충돌 상황에서 육안으로 확인하기 힘든 재료의 손상거동을 파악하는 것이 중요하며, 이를 구현할 수 있는 유한요소모델을 통한 연구가 필요하다. 본 연구에서는 일방향 적층 복합재료의 충돌 해석에 대해 파손 거동 예측에 적합한 유한요소모델을 구축하였다. 인공신경망 모델을 통해 LS-DYNA에서 제공하는 MAT_54 Enhanced Composite Damage 재료 모델의 교정 파라미터를 역추정하여 획득하였다. 획득한 파라미터에 대한 인공신경망 모델의 결과를 실험결과와 비교하여 신뢰성을 검증하였다. 그 결과, 교정 파라미터의 최적화를 통해 실험에 대한 정확도를 향상시킨 유한요소모델을 구축할 수 있음을 확인하였다.