• PNF and Movement
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• 제6권2호
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• pp.51-57
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• 2008

Purpose : Mechanical stress activates signaling cascades and leading to a specific response of a network of signaling pathways. The purpose of this study is to review the effect of mechanical stress-induced adaptation in skeletal muscle involves a biological mechanisms. Methods : This is literature study with Pubmed, Medline and books. Results : Skeletal muscle tissue demonstrates a malleability and may adjust its metabilic response, vascularization and neuromuscular characteristic makeup in response to alteration in functional demands. The adaptation in skeletal muscle involoves a multitude of signalling mechanisms related with insuline-like growth factor, vascular endothelial growth factor, neurotrophins. Conclusions : The identification of the basic relationships underlying the malleability of skeletal muscle tissue is likely to be of relevance for our understanding with PNF technique.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.579-584
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• 2003

Solenoid type magnetic actuator is the device, which could translate the electromagnetic energy to mechanical force. The force generated by magnetic flux, could be calculated by Maxwell stress tensor method. Maxwell stress tensor method is influenced by the magnetic flux path. Thus, magnetic force could be improved by modification of the iron case, which is the route of the magnetic flux. Modified design is obtained by parameter optimization using by Response surface methodology.

• 한국기계가공학회지
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• 제19권4호
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• pp.45-51
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• 2020

In this study, a response spectrum analysis of an electric distributing board (EDB) was conducted to investigate seismic integrity in the design stage. For the seismic analysis, the required response spectra of a safe shutdown earthquake with 2% damping (RRS/SSE-2%) specified in GR-63-CORE Zone 4 was used as the ground spectral acceleration input. A finite element method modal analysis of the EDB was also performed to examine the occurrence of resonance within the frequency range of the earthquake response spectrum. Furthermore, static stress caused by deadweight was analyzed. The resultant total maximum stress of the EDB structure was calculated by adding the maximum stresses from both seismic and static loads using the square root of the sum of the squares (SRSS) method. Finally, the structural safety of the EDB was investigated by comparing the resultant total maximum stress with the allowable stress.

• 한국소음진동공학회논문집
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• 제25권2호
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.331-337
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• 2000

A numerical procedure for contact analysis and calculating subsurface stress was developed. The procedure takes the advantage of signal processing technique in frequency domain to achieve shorter computing time. Boussinesq's equation was adopted as a response function in contact analysis. The validity of this procedure was proved by comparing the numerical results with the exact solutions. The fastness of this procedure was also compared with other algorithm.

• Coupled systems mechanics
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• 제12권5호
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• pp.409-418
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• 2023

A coupled algorithm is proposed which first considers the creation of porous structure of the material and then the simulations of response of mechanical components with porous structure to a variable load history. The simulations are carried out by the Prandtl operator approach in the finite element method (FEM) which enables structural simulations of mechanical components subjected to variable thermomechanical loads. Temperature-dependent material properties and multilinear kinematic hardening of the material can be taken into account by this approach. Several simulations are then performed for a tensile-compressive specimen made of a generic porous structure and mechanical properties of Aluminium alloy AlSi9Cu3. Variable mechanical load history has been applied to the specimens under constant temperature conditions. Comparison of the simulation results shows a considerable elastoplastic stress-strain response in the vicinity of pores whilst the surface of the gauge-length of the specimen remains in the elastic region of the material. Moreover, the distribution of the pore sizes seems more influential to the stress-strain field during the loading than their radial position in the gauge-length.

• 대한기계학회논문집A
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• 제37권11호
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• pp.1331-1337
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• 2013

본 논문에서는 반응표면법을 이용하여 양항력형 수직축 풍력발전기 블레이드의 구조 최적설계를 수행하였다. 선행연구의 구조해석 결과를 살펴보면 양항력형 수직축 풍력발전기 블레이드가 항복강도 이상의 응력이 발생하였으므로, 구조적 안전성을 확보하고자 최적화 기법을 적용한 구조설계를 재수행하였다. 이를 위해 먼저 블레이드에 발생하는 응력에 큰 영향을 주는 설계인자를 선정하였다. 이에 실험계획법 기반 반응표면법을 적용하였다. 목적함수 및 제한조건은 각각 중량 및 허용응력으로 설정하였다. 또한 중량 및 응력에 대한 설계인자의 영향을 평가하기 위한 민감도 해석을 수행하였다. 이러한 과정을 통해 양항력형 수직축 풍력발전기 블레이드의 구조 최적 설계를 수행하였다.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1011-1015
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• 2003

The objectives of this work focus on the differences in responses of paired tendons from different anatomical locations. Tendon specimens were obtained from the hindlimbs of canines and frozen to -70$^{\circ}C$. After being thawed, specimens were mounted in the immersion bath, preloaded to 0.13N, and then subjected to 3% or 4% of the initial length at a strain rate of 5%/sec. It was found that the mechanical responses of anatomically paired tendons were nearly the same within each pair but different between pairs of tendons from different anatomical locations. Although flexor tendons had much larger cross-sectional area than the others, such as peroneus or extensor tendons, the stiffness of the flexor tendons were much lower than the others throughout their stress-strain responses. The nature and causes of these differences in the stiffness are not fully known. However, it is clear that differences in the mechanical response of tendons and other connective tissues are significant to the musculoskeletal performance.

• 한국군사과학기술학회지
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• 제26권1호
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• pp.1-9
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• 2023

The skin structure of sensor pod mounted on the exterior of aircraft can be exposed to the acoustic dynamic load and static load such as aerodynamic pressure and inertial load during flight. Fatigue life prediction of structural model under acoustic load should be performed and also differential stiffness of model modified by static load should be considered. The acoustic noise test spectrum of MIL-STD-810G was applied to the structural model and the stress response power spectral density (PSD) was calculated. The frequency response analysis was performed with or without prestress induced by inplane static load, and the response spectrum was compared. Time series data was generated using the calculated PSD, and the time and frequency domain fatigue life were predicted and compared. The variation of stress response spectrum due to static load and predicted fatigue life according to the different structural model considering mean stress were examined and decreasing fatigue life was observed in the model with prestress of compressive static load.

• Nuclear Engineering and Technology
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• 제47권5호
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• pp.633-645
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• 2015

In order to analyze the mechanical properties of two-way different configurations of prestressed concrete members subjected to axial loading, a finite element model based on the nuclear power plant containments is demonstrated. This model takes into account the influences of different principal stress directions, the uniaxial or biaxial loading, and biaxial loading ratio. The displacement-controlled load is applied to obtain the stress estrain response. The simulated results indicate that the differences of principal stress axes have great effects on the stress-strain response under uniaxial loading. When the specimens are subjected to biaxial loading, the change trend of stress with the increase of loading ratio is obviously different along different layout directions. In addition, correlation experiments and finite element analyses were conducted to verify the validity and reliability of the analysis in this study.