The abstract should clearly state the purpose and nature of the investigation while summarizing the key conclusions in English only. It should be a single paragraph consisting of no more than 200 words. This study presents a method to enhance the seismic performance of a stacked stone pagoda by utilizing a Ball Vibration Absorber (BVA). The governing equations of motion for sliding, the primary failure mode of the stacked stone pagoda, were derived, and a numerical model was developed. Through various numerical analyses, the optimal design parameters of the BVA were identified to maximize its seismic control effectiveness for the pagoda. The BVA device can increase the critical seismic acceleration at which the sliding mode occurs in the structure. Moreover, the seismic control performance of the BVA improves with an increase in the mass of the sphere and the coefficient of friction between the layers. Conversely, as the applied seismic acceleration rises, the effectiveness of the BVA in controlling seismic responses diminishes, although a certain level of control effect is maintained. Finally, as long as the sphere of the BVA maintains a specific range of rolling motion, the radius of the sphere or rolling radius does not significantly impacts its seismic control performance.

This study presents the results of compression, drop impact, and vibration durability analyses conducted to evaluate the mechanical reliability of Battery Pack Cases (BPCs) in electric vehicle (EV) systems. BPCs are essential structural components that must endure compressive loads, impact forces, and vibrational fatigue. Finite Element Analysis (FEA) was applied to a representative BPC model to assess deformation, impact resistance, and vibration endurance. The results indicate that the BPC maintained integrity within yield strength limits under compressive loading and effectively absorbed energy under drop impact. Furthermore, Power Spectral Density (PSD) analysis identified stress concentration regions, providing insights for structural optimization. Overall, the findings support the development of lightweight and reliable BPC designs for advanced EV applications.

To improve vibration reduction in the railway vehicle, the semi-active suspension system using MR damper was developed and the vibration performance of the passive suspension system and a semi-active MR suspension system was compared. For the experiment, the MR damper and suspension system were designed and manufactured. Tensile and compression tests were performed on the MR damper while varying the input current. The damping force of the MR damper was measured and analyzed using the Bingham model. The railway vehicle was modeled with 9 degrees of freedom, and the sky hook control algorithm was simulated using the MR damper, using the Bingham model. This verified the effectiveness of the sky hook controller. Furthermore, to compare the vibration performance of the railway vehicle, the driving test was conducted with the MR damper and the passive damper. The lateral acceleration vibration reduction performance of the suspension system with MR dampers and passive dampers was verified, and it was confirmed that the vibration reduction performance of the vehicle with the semi-active suspension system using MR damper was approximately 50% better than that of the vehicle with the passive damper.

전기추진 선박의 추진축계 이상상태는 심각한 선박 운항 장애를 초래할 수 있으므로, 추진 시스템의 상태를 정확히 진단하고 사전에 예방 유지보수를 수행하는 Prognostics and Health Management(PHM) 기술의 필요성이 증가하고 있다. 본 연구에서는 전기추진 선박 의 추진축 이상상태를 조기에 감지하고 진단하기 위하여 진동 데이터를 기반으로 한 머신러닝 기반 PHM 시스템의 개발과 성능 평가를 수행하였다. Land-Based Testing System(LBTS) 시스템에서 수집된 정상 상태와 축 정렬 이상 상태(0.5 mm, 1.0 mm, 1.5 mm)의 진동 데이터를 활용하여 데이터 전처리 및 특성 추출을 수행하였다. 연구에서는 Fully Connected Neural Network(FCNN) 및 Convolutional Neural Network(CNN)을 적용하여 이상 상태를 진단하는 모델을 개발하고 비교 분석하였다. FCNN 기반 모델은 단순한 구조로 빠른 학습이 가능 하여 실시간 모니터링에 적합한 반면, CNN 모델은 미세한 상태 변화를 효과적으로 탐지하는 데 탁월한 성능을 보였다. 성능 평가 결과 FCNN 모델은 평균 95% 이상의 정확도를 나타냈으며, CNN 모델은 이보다 더욱 향상된 성능을 제공하였다. 본 연구를 통해 개발된 진동 기반 PHM 시스템은 전기추진 선박 추진축 이상상태를 효과적으로 조기에 진단할 수 있는 능력을 입증하였다. 이러한 연구 성과는 전기 추진 선박의 안전하고 효율적인 운항을 위한 신뢰성 높은 유지보수 전략 수립에 중요한 기여를 할 것으로 기대된다. 향후 연구로는 데이 터 품질 개선 및 추가적인 딥러닝 모델 적용을 통한 성능 향상을 목표로 한다.

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.

연안 및 근해를 운항하는 천수선박은 프로펠러의 잠김 깊이가 부족하여 추진 효율이 저하되는 문제가 발생할 수 있다. 이를 개선하기 위해 선미 하부에 Y형 또는 I형 스트럿 구조물을 설치하여 프로펠러 축을 지지하고, 프로펠러를 보다 깊이 잠기도록 설계하는 방법이 널리 적용되고 있다. 그러나 스트럿 베어링의 적용 방식과 위치는 추진축계의 유연성 및 진동 특성에 큰 영향을 미치므로, 초기 설계단계에서 적절한 축계 배치가 필수적이다. 본 연구에서는 스트럿 구조를 갖는 선박을 대상으로, 베어링의 수와 배치에 따른 추진축계 의 정렬 특성과 횡진동 거동을 분석하였다. Y형 스트럿 베어링과 선미관 베어링이 조합된 기존 축계는 높은 횡방향 유연성을 확보하였으 나, 프로펠러 블레이드 통과 주파수와 고유진동수가 근접하여 공진 위험이 존재함을 확인하였다. 이를 해결하기 위해 선미관 베어링을 제 거하고, I형 스트럿 베어링으로 대체하는 새로운 베어링 배치를 제안하였으며, 반력영향계수와 진동모드 해석을 통해 최적의 설치 위치를 도출하였다. 해석 결과, I형 스트럿 베어링을 FR.10~FR.11 구간에 배치하는 경우 정렬 안정성과 공진 회피 측면에서 가장 우수한 성능을 나타내었다. 본 연구는 스트럿 베어링을 갖는 천수선박의 추진축계 설계 시, 유연성과 진동 특성을 동시에 고려한 최적 베어링 배치 가이 드라인을 제시한다는 점에서 의의가 있다.

이 연구에서는 원전 시설물의 부지응답해석 및 지반-구조물 상호작용 해석 등 다양한 동적 문제에 효율적으로 활용할 수 있는 무작 위진동이론(random vibration thoery, RVT) 방법론을 사용하여 원전 구조물에 설치된 기기의 지진취약도 분석기법을 제안한다. RVT 에 기반한 해석기법은 입력지반운동의 시간이력을 직접적으로 필요로 하지 않기 때문에 우리나라와 같이 강진지진기록이 충분하지 않은 지역에서 유용한 방법이다. 입력지반운동의 파워스펙트럼밀도(power spectrum density, PSD) 함수를 사용하여 대상 지반-구조 물 상호작용계의 추계학적 지진응답해석을 수행하고, 구조물 내부에 설치된 기기의 유사가속도에 대한 PSD 함수를 산정한다. 이 PSD 함수에 무작위진동 첨두응답의 확률분포를 추정할 수 있는 첨두값 계수를 적용하여 기기 유사가속도의 첨두값, 즉 구조응답스 펙트럼의 누적분포함수를 추정하고, 기기의 고장 조건을 적용하여 기기 고장 확률과 취약도곡선을 산정한다. 제안한 RVT 방법론에 근거한 지진취약도 분석기법을 균질 반무한 경암 및 연암 지반에 놓인 원전 구조물에 설치된 기기에 적용하고, 응답이력 방법론에 의 한 결과와 비교하여 제안한 기법의 정확성을 검증한다.

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%.