• Journal of Biosystems Engineering
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• 제42권4호
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• pp.251-257
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• 2017

Purpose: A chisel mounted on working implement, such as agricultural machinery used in irregular farming conditions, is subjected to highly variable fatigue loading during work. To ensure the safety of the chisel on a working implement for the duration of its service life, fatigue testing must be performed with the proper fatigue test load conditions. In this study, working loads for a chisel were developed by reconstructing loads from strain gage data collected during field tests and used to conduct fatigue tests on the chisel component. Methods: FE analysis with nCode software was utilized to select the proper quantity and locations of strain gages for load measurements. A fatigue test was performed to experimentally verify the fatigue strength of the chisel and to evaluate the validity of the load history developed with the load reconstruction technique. Results: A strain history for the chisel was obtained from data collected during field tests. The data was filtered for the 14-16 km/h speed range, connected, and merged. The chisel load history was developed using the load reconstruction technique. The resulting load history was expressed as a load spectrum using the rain-flow counting method. Conclusions: A fatigue test was conducted on a chisel under a constant load condition with an equivalent load amplitude and number of cycles, as calculated by Miner's Rule for linear damage accumulation. During the fatigue test, there were no cracks at any position. It is concluded that the fatigue test method proposed in this study can be utilized successfully as a durability evaluation method for the chisel.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1527-1532
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• 2008

45% of the sports accidents is the knee damage and the representative case is the damage of an Anterior Cruciate Ligament (ACL) and the Posterior Cruciate Ligament(PCL). Although the past different views of ACL reconstruction comes to an agreement, the disputes of PCL is remained yet. The most important engineering approach for these various surgery techniques is accurately to understand and to evaluate the fatigue behavior depending on the stress flow and the stress distribution under the allotted load and the cyclic load, which are caused by the graft fixing device, the proximal tibia of the PCL reconstructing structure. Therefore, this study is the basic research of these above facts. The current transtibial tunnel surgery using the cadaveric Achilles tendon grafts is chosen for the various PCL reconstruction. The relationships between the slippage, the extension ratio, and the slippage ratio by the heel bone fixing method and the soft tissue fixing method of the Achilles tendon were also defined. This research will be the essential data to help the resonable operating techniques for the next PCL reconstruction.

• Smart Structures and Systems
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• 제29권4호
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• pp.599-616
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• 2022

Bridge displacement contains vital information for bridge condition and performance. Due to the limits of direct displacement measurement methods, the indirect displacement reconstruction methods based on the strain or acceleration data are also developed in engineering applications. There are still some deficiencies of the displacement reconstruction methods based on strain or acceleration in practice. This paper proposed a novel method based on long short-term memory (LSTM) networks to reconstruct the bridge dynamic displacements with the strain and acceleration data source. The LSTM networks with three hidden layers are utilized to map the relationships between the measured responses and the bridge displacement. To achieve the data fusion, the input strain and acceleration data need to be preprocessed by normalization and then the corresponding dynamic displacement responses can be reconstructed by the LSTM networks. In the numerical simulation, the errors of the displacement reconstruction are below 9% for different load cases, and the proposed method is robust when the input strain and acceleration data contains additive noise. The hyper-parameter effect is analyzed and the displacement reconstruction accuracies of different machine learning methods are compared. For experimental verification, the errors are below 6% for the simply supported beam and continuous beam cases. Both the numerical and experimental results indicate that the proposed data fusion method can accurately reconstruct the displacement.

• Archives of Plastic Surgery
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• 제33권6호
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• pp.688-694
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• 2006

Purpose: Reconstruction of the craniofacial defects can be carried out with autogenous tissues, allogenic implants, or alloplastic materials. Titanium mesh systems have been used for bony reconstruction in non load-bearing areas. They offer several advantages: immediate availibility without any donor site morbidity, easy handling, stable 3-D reconstruction, and low susceptibility to infection. The aim of this study is to evaluate the usefulness and complications of titanium mesh system in the reconstruction of the craniofacial defects. Methods: From Jan. 2000, to Dec. 2004, we performed reconstruction of craniofacial bone defects in 21 patients who had benign or malignant tumor and fracture events in the cranium, orbit, nasal bone, maxilla, zygoma and the mandible. The size of the defects ranged from $1.0{\times}1.5cm$ to $12{\times}10cm$. Two different mesh systems, micro-titanium augmentation mesh and dynamic mesh was used for bony reconstruction in non load-bearing areas. The patients were evaluated from 1 to 4 yrs clinically and radiographically with a mean follow up period of 1.5 yrs. Results: There were no serious complications, including wound infection, foreign body reaction, exposures or loos of the mesh, central infection and pathologic findings of bone around mesh exception of one patient, who had expired of skull base tumor recurrence. Long-term stability of the reconstructions and the overall functional and aesthetic outcome was excellent. Conclusion: Our experiences demonstrate that the Titanium mesh system is a relatively safe and efficient method in the craniofacial reconstruction and have broadens our choices of therapeutic procedures in the craniomaxillofacial surgery.

• Structural Engineering and Mechanics
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• 제88권4호
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• pp.301-309
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• 2023

In this paper, a new modified conjugate gradient (MCG) method is presented which is based on a new gradient regularizer, and this method is used to identify the dynamic load on airfoil structure without and with considering random structure parameters. First of all, the newly proposed algorithm is proved to be efficient and convergent through the rigorous mathematics theory and the numerical results of determinate dynamic load identification. Secondly, using the perturbation method, we transform uncertain inverse problem about force reconstruction into determinate load identification problem. Lastly, the statistical characteristics of identified load are evaluated by statistical methods. Especially, this newly proposed approach has successfully solved determinate and uncertain inverse problems about dynamic load identification. Numerical simulations validate that the newly developed method in this paper is feasible and stable in solving load identification problems without and with considering random structure parameters. Additionally, it also shows that most of the observation error of the proposed algorithm in solving dynamic load identification of deterministic and random structure is respectively within 11.13%, 20%.

• Smart Structures and Systems
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• 제28권6호
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• pp.827-838
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• 2021

The dynamic displacement is considered to be an important indicator of structural safety, and becomes an indispensable part of Structural Health Monitoring (SHM) system for high-speed railway bridges. This paper proposes an indirect strain based dynamic displacement reconstruction methodology for high-speed railway box girders. For the typical box girders under eccentric train load, the plane section assumption and elementary beam theory is no longer applicable due to the bend-torsion coupling effects. The monitored strain was decoupled into bend and torsion induced strain, pre-trained multi-output support vector regression (M-SVR) model was employed for such decoupling process considering the sensor layout cost and reconstruction accuracy. The decoupled strained based displacement could be reconstructed respectively using box girder plate element analysis and mode superposition principle. For the transformation modal matrix has a significant impact on the reconstructed displacement accuracy, the modal order would be optimized using particle swarm algorithm (PSO), aiming to minimize the ill conditioned degree of transformation modal matrix and the displacement reconstruction error. Numerical simulation and dynamic load testing results show that the reconstructed displacement was in good agreement with the simulated or measured results, which verifies the validity and accuracy of the algorithm proposed in this paper.

• 대한물리치료과학회지
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• 제31권1호
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• pp.46-52
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• 2024

Background: This study aims to investigate compensatory strategy in a dog with glenoid dysplasia using kinetic gait analysis before and after reconstruction of medial patellar luxation. Design: Case report Method: On the platform, gait analysis was evaluated for a dog with congenital luxation and bilateral medial patellar luxation (MPL). A dog was evaluated for maximal vertical force (MVF), body load distribution (BLD), and symmetry index (SI), including the left forelimb with congenital luxation before MPL surgery, 15 days of surgery, and 40 days of surgery. Result:: In the comparison between the preoperative and the 15 days of surgery, the MVF of the bilateral forelimbs, especially in the non-affected forelimbs, increased, and the SI also increased. For BLD, the maximum load distribution increased, but the total load distribution decreased. In the comparison of 15 days and 40 days of surgery, MVF and BLD increased, and SI decreased on 40days of surgery. Conclusions: In a dog, the shift in weight load to the non-affected side occurs all the limbs, affecting the peak vertical force, weight load distribution, and symmetry index.

• 한국정보통신학회논문지
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• 제12권12호
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• pp.2271-2276
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• 2008

본 논문에서는 3D 영상의 해상도 개선을 위한 크기가변 확대 기법 기반의 컴퓨터적 집적 영상 재생 방법을 제안한다. 먼저 컴퓨터적 집적 영상 재생 방법에서 요소 영상 사이의 간섭 문제를 설명한다. 큰 확대개수는 요소 영상의 확대 중첩 과정에서 큰 간섭을 야기하여 재생 3D 영상의 해상도를 저하시킨다. 이 간섭 문제를 극복하기 위해서 최소 확대 계수를 계산하는 방법을 제안한다. 새로운 최소 확대 계수는 해상도가 향상된 3D 영상을 제공하며, 제안하는 방법은 기존의 방법보다 계산량이 작다. 제안하는 방법의 유용함을 보이기 위해서 컴퓨터 복원 실험을 수행하고 그 결과를 보고한다.

• Advances in nano research
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• 제13권3호
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• pp.247-257
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• 2022

Extraordinary properties of nanocomposites make them a primary replacement for many conventional materials. Anterior cruciate ligament (ACL) reconstruction, which is a frequent surgery in sport activities, is one of the fields in which nanocomposites could be utilized. In the present study, the mechanical properties of different porous scaffolds made from graphene nano-composites are presented ad load bearing capacity of these materials is calculated using finite element method. The numerical results are further compared with experimental published data. In addition, several geometrical and material parameters are analyzed to find the best configuration of nanocomposite scaffolds in reconstruction of ACL. Moreover, coating of detoxification chemicals are extremely easier on the nano-structured materials than conventional one. Detoxification potential of nano-composites in the injured body are also discussed in detail. The results indicated that nano-composite could be successfully used in place of auto- and allografts and also instead of conventional metallic screws in reconstruction of ACL.

• 한국정보전자통신기술학회논문지
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• 제9권2호
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• pp.148-154
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• 2016

최근 들어 전력계통에서 비선형 부하의 증가와 분산전원의 증가로 전력 품질에 관한 관심이 증대 되고 있다. 전력신호로 부터 전력품질관련 파라미터 검출과 특징추출 그리고 이를 이용한 품질 개선 방안 마련을 위해 전력신호의 지속적인 모니터링이 필요하다. 본 논문에서는 전력신호의 모니터링을 위한 전력신호의 압축 저장과 저장된 신호의 복원이 가능한 방법을 제시한다. 전력신호 압축은 에너지 압축 성능이 우수한 DCT를 이용하며 압축된 신호의 복원에는 IDCT 과정을 거친다. 그리고 신호의 압축률을 높이기 위해 DCT계수를 크기에 따라 정렬하며 복원에서는 DCT계수를 원위치로 재배열하는 기법을 사용한다. IEC표준에서 규정한 고조파 크기에 의해 합성한 신호를 이용하여 압축과정을 거처 복원된 신호와 원 신호와의 오차를 비교함으로서 신호제안기법의 성능을 평가한다.