This study investigates the vibration characteristics of an aluminum subframe for small and high-speed vessels through modal and resonance analysis using the finite element method (FEM). Due to the low stiffness and damping of aluminum, concerns arise over structural resonance and fatigue. A 3D model based on actual design drawings was analyzed to extract six natural frequencies and corresponding mode shapes. Significant deformation was observed in the first and second modes (90.65 Hz, 110.60 Hz), which may overlap with operational frequencies. The fifth mode (263.70 Hz) showed high amplitude with Y-axis concentration, indicating lateral resonance vulnerability. Deformation ratios were used to identify dominant vibrational directions. Based on the findings, design strategies such as structural reinforcement, RPM adjustment, and damping device application were proposed to improve vibration safety in the early design stage.

The purpose of this paper is to investigate the vibration phenomenon occurring in the structure such as a ship with the hemispherical substructure and operating at fixed frequency, and to suggest the active vibration control method using the Fx-LMS algorithm to reduce vibration amplification. In order to study the possibility of reducing vibration in the hemispherical structure, the active vibration control model was developed and a vibration control experimental device for the hemispherical structure was constructed. The narrowband Fx-LMS algorithm was developed to enable precise real-time control at a specific frequency, and the secondary path for dynamic control was modeled with two coefficients per frequency. The experimental device is equipped with three exciters, six 3-axis actuators, and six 3-axis error sensors, which can acquire 18 error sensor signals. Real-time secondary path tracking was possible with the secondary path consisting of two coefficients and the control algorithm, and effective vibration control performance was confirmed through this. And the experimental results of active vibration control of the exciter for three frequencies showed that the exciter vibration was reduced by a minimum of 63.7% and a maximum of 97.7%, which shows the possibility of reducing the vibration of the structure in real time using the proposed method.

Ensuring operational safety and reliability in Unmanned Aerial Vehicles (UAVs) necessitates advanced onboard fault detection. This paper presents a novel, mobility-aware multi-sensor health monitoring framework, uniquely fusing visual (camera) and vibration (IMU) data for enhanced near real-time inference of rotor and structural faults. Our approach is tailored for resource-constrained flight controllers (e.g., Pixhawk) without auxiliary hardware, utilizing standard flight logs. Validated on a 40 kg-class UAV with induced rotor damage (10% blade loss) over 100+ minutes of flight, the system demonstrated strong performance: a Multi-Layer Perceptron (MLP) achieved an RMSE of 0.1414 and R² of 0.92 for rotor imbalance, while a Convolutional Neural Network (CNN) detected visual anomalies. Significantly, incorporating UAV mobility context reduced false positives by over 30%. This work demonstrates a practical pathway to deploying sophisticated, lightweight diagnostic models on standard UAV hardware, supporting real-time onboard fault inference and paving the way for more autonomous and resilient health-aware aerial systems.

In this study, an active vibration control experiment was conducted on a display manufacturing system weighing approximately 15 tons. Three pneumatic shakers were installed underneath the equipment to excite the entire structure at three different frequencies. On the top side of the equipment, four inertial-type electromagnetic actuators capable of generating forces in the x, y, and z directions were mounted, enabling 12 degrees of freedom to be controlled. At locations near the actuators, four tri-axial accelerometers were installed to obtain 12 error signals. Vibrations at three distinct frequencies induced by the pneumatic shakers were measured at these 12 locations using the accelerometers. Active vibration control was performed by driving the inertial actuators using a narrow-band Fx-LMS algorithm to reduce the measured error signals. As a result of the control, the vertical vibration at 24 Hz was successfully reduced by 10.95 dB.

NVH(Noise, Vibration, and Harshness) characteristics are critical indicators for evaluating automotive quality and diagnosing mechanical issues through abnormal vibrations during driving. Among various components, tires are the only part of the automotive in direct contact with the road, making them a major source of noise and vibration. Tire-related anomalies not only affect ride comfort but can also pose serious safety hazards. This study presents a diagnostic approach that utilizes NVH analysis, wheel balance inspection, and RFV(Radial Force Variation) measurement to identify and repair tire faults. Through case analysis, it was confirmed that abnormal vibrations caused by internal moisture accumulation and structural deformation of tires could be accurately diagnosed and addressed. The proposed method enables early detection of tire-related issues, providing a preventive maintenance strategy and contributing to enhanced automotive safety and reliability.

진동자극에 따른 틸라피아(Oreochromis niloticus)의 스트레스 반응에 대한 기초자료를 얻고자, 혈액[(cortisol, glucose, lactic acid, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total protein (TP), red blood cell (RBC), hemoglobin (Hb), hematocrit (Ht), 조직(liver, kidney, intestine) 및 성장을 분석하였다. 실험어류는 틸라피아(평균 전장 11.7±0.4 cm, 평균 체중 23.4±3.7 g)를 사용하였으며, 28일 동안 실험을 진행하였다. 실험구는 대조구, T1(10:00, 19:00), T2(10:00, 13:00, 16:00 19:00)로 각각 1시간씩 진동을 주었다. 혈액, 혈장, 간, 신장 및 장 샘플은 진동 노출 후 0, 7, 14, 21 및 28일에 채취하여 분석하였다. 혈장 코티졸 농도는 21일째 대조구와 T1에서 유의하게 높았으나, 28일째 감소하였다. 반면에, T2에서는 28일째 다른 실험군보다 유의하게 높아졌다. 젖산은 14일째 T2에서 다른 실험구에 비해 유의하게 높아졌다. 혈장 AST 및 ALT는 T2에서 실험기간동안 유의적으로 높아졌다. T1과 T2는 실험 기간 동안 혈장 TP가 증가하였다. T1은 28일째 다른 실험구에 비해 RBC, Hb 및 Ht가 유의하게 높아졌다. 조직관찰 결과, T2에서 간조직은 혈액 정맥동의 울혈 및 확장, 비대, 침윤, 공포화, 신장에서는 흑색 대식세포 증가, 간질 부종 및 장에서 괴사가 관찰되었다. 성장은 진동 자극 횟수가 증가함에 따라 최종 무게(final body weight), 체중성장률(growth rate for body weight, GRW), 일일성장률 (specific growth rate, SGR) 및 사료효율(feed efficiency, FE)이 대조군에 비해 감소하였으나 유의적인 차이는 보이지 않았다.

As the integration of devices in electronics manufacturing increases, there is a growing demand for thermal interface materials (TIMs) with high through-plane thermal conductivity. Vertically aligned carbon fiber (CF) thermally conductive composites have received considerable attention from researchers. However, the presence of significant interfacial thermal resistance at the interface between CFs and polymer presented a significant challenge to achieving the desired thermal conductivity, even in highly vertically aligned structures. Here, in addition to developing a polymer-based thermally conductive composite based on highly oriented CFs, we employed the Diels–Alder reaction to enhance the interfacial bonding between the CFs and the polymer matrix. Notably, we proposed the thermal conductivity enhancing mechanism of the highly oriented CFs filled silicone rubber (SR) composite originated from the strengthened interfacial bonding. The results indicated that the Diels–Alder reaction facilitated an increase in the thermal conductivity of the composite from 17.69 Wm− 1 K− 1 to 21.50 Wm− 1 K− 1 with a CF loading of 71.4 wt%. Additionally, a novel nano-indentation test was employed to analyse the interfacial strengthening of composites. Our research have significant implications for the advancement of thermal management in the field of electronics and energy, particularly with regard to the development of high-performance thermally conductive composites.

The blocked force from the electric vehicle compressor is transmitted through the mount to the body side, serving as a primary source of body vibration during air conditioner operation at idle. Accordingly, a method is required during the compressor development stage to quantitatively evaluate the blocked force and analyze its influence for each transmission path. In this study, the blocked force at the outlet of an electric compressor was measured, and a test model was constructed to predict the response of the vehicle body using the Frequency-Based Substructuring(FBS) method. The 6-DOF dynamic stiffness of the bushing up to 500 Hz, not measurable with the elastomer, was successfully obtained using the inverse substructuring(IS) method. Finally, the proposed method was validated by the close match between predicted and measured body vibrations for both conventional and low dynamic stiffness bushings.

This study explores structural dynamics using experimental modal analysis with tri-axial accelerometers and advanced signal processing. By improving the accuracy of modal parameters such as natural frequencies and damping ratios, the research enhances vibration analysis techniques. The findings have applications in structural health monitoring, predictive maintenance, and mechanical system optimization.

The purpose of this study is to examine the application and effectiveness of tuned mass dampers for reducing cabinet vibration in plants. Cabinet with lower structural rigidity than plant subject to seismic design standards is susceptible to resonance. SolidWorks was used for 3D modeling of the cabinet, and ANSYS Workbench was used to create a mesh. The vibration characteristics of the cabinet were investigated through modal analysis, and the possibility of resonance and vibration reduction performance of the cabinet were evaluated. The number of modes in the cabinet was set to 100, and the frequency and modal participation mass ratio of each mode were calculated. In order to examine the possibility of vibration reduction by tuned mass dampers, the vibration response characteristics of cabinets with and without tuned mass dampers were compared. The analysis results showed that the third mode had a significant effect on the dynamic behavior of the cabinet and that the modal participation effective mass ratio was larger than that of other vibration modes. And as the mass of the tuned mass damper increased, the vibration response of the cabinet decreased significantly, and the peak value of the cabinet decreased by up to 52%.

무작위진동이론(random vibration thoery, RVT)에 기반하여 원전 시설물 부계통의 지진응답해석과 확률론적 지진안전성평가를 위 한 구조응답스펙트럼(in-structure response spectrum, ISRS) 스케일링 기법을 새로이 제안한다. 새로운 방법은 대상 구조물의 동적 특 성에 대한 정보를 활용하지 않고, 구조응답과 지진지반운동의 파워스펙트럼밀도(power spectral density, PSD) 함수의 비를 사용한다. 무작위 진동의 첨두값 계수를 사용하여 진동의 PSD 함수로부터 첨두값의 통계적 특성과 무작위 진동의 응답스펙트럼을 추정할 수 있으므로, 반복계산을 통해 기존 지반운동 응답스펙트럼과 ISRS에 부합하는 PSD 함수와 그 비례계수를 도출한다. 이 계수를 신규 지 반운동 응답스펙트럼에 부합하는 PSD 함수에 적용하여, 신규 ISRS의 PSD 함수와 이에 대응하는 ISRS를 도출하는 스케일링을 수행 한다. 제안된 RVT에 기반한 새로운 스케일링 기법을 예제 원전 구조물에 적용하고, 응답이력방법에 의한 참조해와 비교하여 제안한 새로운 스케일링 기법이 정확성을 확인할 수 있다. 비례계수를 산정하기 위한 기존의 근사 방법들과 비교하여, 새로운 스케일링 기법 은 ISRS의 첨두 등을 잘 표현할 수 있는 것을 관찰할 수 있다.

This study is a preliminary investigation into a method for updating analytical models using actual vibration measurement data to improve the reliability of the seismic performance evaluations. The research was conducted on 26 models with various parameters, aiming to develop an optimal analytical model that closely matches the natural frequencies of the actual building. By identifying the dynamic characteristics of the target building through vibration measurements taken just before the demolition of the structure, the natural frequency analysis results of the analytical models were compared to the measured data. Based on this comparison, an optimized method for adjusting the parameters of the analytical models was derived. Throughout the analysis, various parameters were adjusted, and the eigenvalue analysis results were corrected by comparing them with vibration measurements. Among the comparative analytical models, the model with the lowest error rate was selected. The results showed that, in all cases, the analytical model with a concrete compressive strength of 16 MPa (based on actual measurements), pin boundary conditions, and an idealized strip footing cross-section had the closest match to the actual building's natural frequencies, with an average error of less than 8%.

In this study, a control algorithm was developed to suppress the free vibration amplitude of a cantilever beam with time-varying dynamic characteristics. In other words, since it is assumed that the natural frequency and mode shape of the vibrating structure are not fixed, the system model of the vibrating structure was not used in the control algorithm. A single electromagnet was chosen as the actuator, so the attractive force was applied to only one fixed location in the structure. Through experiments, the proposed control algorithm is proven to effectively suppress the amplitude of vibration even when the dynamic characteristics of the cantilever beam change. Contrary to the usual active vibration control method, the proposed algorithm is just simple and intuitive without complicated mathematics in the modeling and control process. However, the proposed control method is very effective to suppress the vibration even when the dynamic characteristics of the target structure is not exactly known, as is often the case in industries or laboratories.

Background: This study aims to analyze the trends in research related to the application of whole-body vibration exercise in stroke patients, the methods used, and the effects of such applications. Additionally, it seeks to propose future directions for research on whole-body vibration exercise in stroke patients and provide foundational data for future studies. Objectives: The purpose of this study was to analyze the trends in research on the application of whole-body vibration exercise in stroke patients, focusing on the methods used and the resulting effects. Design: A scoping review. Methods: This is a literature review aimed at identifying trends in whole-body vibration exercise research for stroke patients published in Korea between 2000 and March 2024. The study followed the five stages of the scoping review procedure proposed by Arksey and O’Malley. Results: The remaining one was a comparative study of the effects between vibration frequencies. The main findings from the literature showed statistical significance in 15 studies, excluding 3 articles. Additionally, 13 studies reported that the whole-body vibration exercise group demonstrated more significant improvements than the control group, while 1 study found the control group had more significant effects than the whole-body vibration exercise group. The remaining study compared the effects between different vibration frequencies. Conclusion: Based on the findings of this study, there is a need for more systematic reviews and meta-analyses to evaluate the effectiveness and quality of interventions. These should focus on systematically analyzing the outcomes of vibration exercise programs applied to stroke patients and the relevant dependent variables.

In order to design a seismic safety of a cabinet affected by an earthquake, vibration analysis was performed using a model cabinet. In order to analyze the vibration characteristics of the cabinet under earthquake conditions, 3D finite element analysis was performed using ANSYS Workbench and SolidWorks. The modal analysis of the cabinet showed nine natural modes and natural frequencies, and showed the deformation and vibration of the cabinet panel for each mode. The frequencies of the 1st and 2nd modes, which are low modes, were 10% of the natural frequency value of the 9th mode, so it was easy to predict the possibility of resonance occurrence. The response spectrum due to the earthquake showed that the displacement, acceleration, and stress distribution of the cabinet had different behaviors in the x, y, and z directions, and especially showed very large values in the z direction. Although the vibration characteristics of the structure were evaluated using the modal characteristics and response spectrum for the cabinet, research on the application of a tuned mass damper is necessary for the dynamic characteristics process of the cabinet due to an earthquake and resonance reduction.

The multi-local resonance metamaterial is based on the local resonance mechanism of resonators, effectively blocking wave propagation within multiple resonant frequency ranges, a phenomenon known as band gaps. In practical applications for vibration reduction, the goal is to achieve wide-band vibration attenuation at low frequencies. Therefore, this study aims to improve the vibration reduction performance of multi-local resonance metamaterials by lowering the band gap frequency and expanding the band gap width. To achieve this, an objective function was formulated in the optimization problem, considering both the frequency and width of the band gap, with the geometric shapes of the multiple local resonators selected as design variables. The Sequential Quadratic Programming (SQP) technique was employed for optimization. The results confirmed that the band gap was generated at lower frequencies and that the band gap width was expanded.

This study proposes a steel plate retrofit method and a polyurea method to improve the structural stability and usability of a factory floor slab with a thickness of 120mm. To assess vibration changes, vibrations were measured before and after retrofit. A numerical analysis model was also developed to evaluate improvements in structural safety and usability. The natural frequency increased from 11.4Hz to 17Hz through steel plate reinforcement, confirming an increase in slab stiffness. The damping ratio increased from 2.3% to 3.2% with polyurea reinforcement, indicating improved vibration reduction. Additionally, numerical analysis modeling showed that the natural frequency increased from 13.9Hz to 16.2Hz due to the steel plate reinforcement, enhancing the dynamic characteristics of the floor slab and confirming the reliability of the analysis model.

In order to prevent disconnection of the hydraulic pump EDV cable, this study judged the vibration generated by the pump as the greatest effect on disconnection, and confirmed the vibration effect. And it had a structure that was vulnerable to vibration because of the wire flow space inside the EDV cable connector. After applying the improved adapter, vibration analysis, excitation test, and bending strength test were performed to confirm the effectiveness of design change and improvement. As a result of vibration analysis, the amount of vibration was reduced by about 10 times compared to the existing product, and the strength increased by about 4 times in the bending strength test was confirmed to increase the effect of preventing disconnection due to vibration.