When developing a new motor, a high-speed load test is performed using dynamo equipment to calculate the efficiency of the developed motor using the collected dynamo data. When connecting the test motor and the dynamo used as a load, abnormal noise and vibration may occur in the test equipment rotating at high speed due to misalignment of the connecting shaft and looseness of the connection, which may lead to a safety accident. In this study, three vibration sensors are attached to the surface of bearing parts of the test motor to measure the vibration value, and statistics such as kurtosis, skewness, and percentiles are obtained in order to clearly express the pattern of the measurement data. With these statistics, machine learning models are developed. The developed model in this way can be used as a diagnostic system that can detect abnormal conditions of the motor test equipment through monitoring the motor vibration data during the motor test.

본 연구에서는 드론을 활용한 변위계측에서 드론의 회전진동 보정을 위해 드론 내부의 가속도계를 이용하는 방법 대신에 드 론 영상 내부의 변위가 발생하지 않는 고정점을 활용한 드론의 회전진동 보정방법을 제안하고자 한다. 영상 내부의 고정점을 활용한 드론 회전진동 보정을 위한 예비 연구로서, 카메라를 고정시킨 후 타겟을 회전하여 회전각도를 측정하는 실험과 회전하는 카메라를 통 해 변위가 발생하는 모형구조물의 변위를 계측하는 실험을 통해 카메라의 회전진동이 발생하는 경우 변위 계측정확도를 검증하였다. 변위가 3mm 이하로 발생 시 카메라 진동이 발생하였을 때 계측 신뢰도가 낮은 반면, 변위가 3mm를 초과하여 발생한 경우 비교적 정 확하게 계측되었다.

Recently, measuring instruments for SHM of structures had being developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cable. However, the research on the tall buildings with relatively small vibration levels is insufficient. Therefore, in this paper, we used the wireless MEMS sensor and iPad to compare and analyze the vibration measurements of three tall buildings and two towers.

Recently, measuring instruments for SHM of structures had being developed. In general, the wireless transmission of sensor signals, compared to its wired counterpart, is preferable due to its absence of triboelectric noise and elimination of the requirement for cumbersome cable. Preliminary studies on the continuous vibration measurement of high-rise buildings using MEMS sensors have been carried out. However, the research on the low-rise buildings with relatively small vibration levels is insufficient. Therefore, in this paper, we used the wireless MEMS sensor to compare and analyze the vibration measurements of three low-rise buildings.

With increasing number construction of high-rise building which has about 40 to 60 floors there have been many kinds of problem which related with usage from vibration. To predict response acceleration, it is important to assess correct natural frequency. However, due to the noise of MEMS sensor, it is difficult to measure dynamic characteristic such as natural frequency when measuring ambient vibration using MEMS sensor within cell phone. Therefore, a comparative analysis on vibration measuring applications was performed after measuring ambient vibration of 2 skyscrappers which have height between 133.5~244.3m that are located in Seoul and Observation tower using I-jishin APP with noise reduction function of MEMS sensor in order to verify the effectiveness of low noise type vibration measurement APP.

Cooling towers have been widely applied to control the indoor temperature in the residential area and the living space. At operating the cooling towers, motor, fan and dropping water produce noise and vibration, which diffuse through the air or the solid object, polluting the environment. The standards can be used at estimating noise and vibration emission by showing remarkable economic or social benefits. The purpose of this study is to show the vibration and noise measurement and influence evaluation between cooling towers and semiconductor equipment.

The cases of conducting the vibration measurement using the mobile phone with regard to the building's horizontal vibration are very rare in Korea and foreign countries. Therefore, this study analyzed the horizontal vibration nature of the building using the mobile phone targeting 5 tall buildings, and reviewed about the applicability of the mobile phone vibration measuring instrument through the comparison/verification with the data of the existing vibration measuring instrument. The peak of the measured time series waveform was measured clearly and it showed a similar value to the existing natural frequency.

Cooling towers have been widely applied to control the indoor temperature in the residential area and the living space. At operating the cooling towers, motor, fan and dropping water produce noise and vibration, which diffuse through the air or the solid object, polluting the environment. The standards can be used at estimating noise and vibration emission by showing remarkable economic or social benefits. The purpose of this study is to show the characteristics, measurement methods for the evaluation of noise and vibration in cooling tower.

선박에서의 주요한 진동발생 원인으로는 주기관과 프로펠러에 의한 것이다. 이러한 가진원으로부터 발생한 진동은 선박에 탑재된 장비의 내구성에 악영향을 미치고, 선박의 승조원에게도 불쾌감 등의 나쁜 영향을 미치게 된다. 본 연구에서는 선박에서 발생하는 진동을 계측하지 위한 시스템을 구축하였고 실제 실습선의 거주공간에서 발생하는 진동을 계측하였으며, 계측된 진동을 바탕으로 ISO6954:2000E에 의거하여 거주성 평가를 행하였다.

The goal of this study was to assess the level of vibration in an walking-type cultivator, and to provide a basic information to manage the vibration exposure for farmers. The latent periods of vibration-induced white finger (VWF) were assessed through analyzing the vibration levels and frequency characteristics. Also, vibration acceleration levels based on the daily vibration exposure duration was suggested. The latent periods of vibration-induced white finger were assessed by ISO 5349 method. The latent periods were 4.5 and 10.1 years at 10% and 50% of farmer group, respectively. Also, under ACGIH (American Conference of Governmental Industrial Hygienists) standard, daily vibration exposure duration at 6.7 m/s2 of vibration acceleration has to be less than 4 hours. Therefore, education that maximum working hours should be less than 4 continuous hours is necessary for the operators of walking-type cultivators.

This paper is concerned with the natural periods of ambient vibration and eigenvalue analysis. Ambient vibration tests were conducted to four bearing-wall reinforced concrete buildings ranging from twelve to nineteen stories. The performance of modeling in eigenvalue analysis was investigated using consideration of rigidity out of the plane in the slab and the non-structural bearing wall. Measured natural period was also compared with the value by the KBC2005. Natural period of the short direction in eigenvalue analysis is well fitted with the measured one. In the other hand, Natural period of the long direction in eigenvalue analysis is slightly more overestimated than the measured one. Natural period of the long direction in eigenvalue analysis was found to be enhanced by considering the effect of the stiffness out of the plane of the slab and non-structural wall in the structural modeling.

이 연구에서는 풍력-태양광 하이브리드 가로등 구조물에 대한 동적 응답을 계측하여, 서로 다른 터빈을 적용하였을 때의 진동 특성 및 공진현상을 비교하였다. 2엽 및 3엽 풍력터빈을 적용하였으며, 하이브리드 가로등이 가지고 있는 진동 특성은 가동 중인 조건에서의 동특성과 가진력을 비교하여 분석하였다. 최근 제안된 방법을 통해 가속도 계측자료를 이용하여 변위 응답을 추정하였고, 2엽 풍력터빈을 적용한 경우 동적 변위 응답의 진폭은 공진 하의 조건에서 4~6cm 범위에 있고, 3엽 풍력터빈을 적용한 경우에는 공진이 발생하지 않아 변위는 2mm 이내로 제한됨을 알 수 있었다.

In this research, the measurement of vibration for stay-cable installed in cable stayed bridge was carried out by using wireless accelerometer. The vibration measurement data can be used for the evaluation of safety and serviceability of cable stayed bridge. The acquired data was analyzed for the evaluation of maximum vibration, tension force and fatigue. To verify the reliability of data, the additional measurements with total station and video camera. The data from three different measurement methods showed similarity within 15 % gap.

The main objective of this paper is a feasibility Study for measuring tensile forces in the steel wire which are widely used in various types of prestressed structures. A steel wire serves as a load-bearing element, and electromagnetic-acoustic transducers are used to excite and detect resonant vibrational modes. The results show a promising feasibility on measurement of tensile forces in the steel wire.

When estimate Short Lenth External Tendon's tension by Vibration Measurement Method, We Consider Tendon's Boundary. This paper is a case about estimation of short lenth tendon's tension by using practical formula estimation and stiff string with clamped-clamped boundary conditions.

In the laboratory, the floor vibration should be strictly controlled. However, the researchers had appealed inconvenience due to the floor vibration. Thus, in this study, the floor vibration was measured and evaluated by ISO 10137. Based on the measured data, a finite element analysis model was established and the floor vibration was reduced by installation of two columns

This study was performed to evaluate the cable tension of cable-stayed bridge by using vibration method and Lift-Off Test. As a result, cable tension by the vibration method and Lift-Off Test is most similar.

본 연구에서는 PC교량의 외부텐던의 장력을 평가하기 위하여 신속하고 경제적으로 적용할 수 있는 텐던의 진동을 이용한 고유진동수 측정 방법의 적용성을 검토하였다. 길이별로 다양한 여러 종류의 외부텐던 덕트 표면에 가속도 센서를 부착하고 고유진동수를 측정하였다.센서의 방향과 위치변경 등 여러 종류의 다양한 진동시험을 실시한 결과 고유진동수의 차이는 1% 이내로서 충분한 정확성을 확보하고 있음을 보였다. 측정된 고유진동수로부터 장력을 추정하기 위해서는 현의공식, 다중모드법, 저차 모드의 실용적 공식을 활용한 방법 (Zui et al., 1996), 양단고정 경계조건에 의한 휨강성을 고려한 현의공식 (Sagűѐs et al., 2006) 등의 장력 추정법을 적용하였고 그 결과값을 비교하였다. 휨강성을 반영하지 못한 현의 공식이나, 다중모드법은 길이가 짧은 텐던에 대해 장력을 과대평가하는 결과가 도출되어 텐던의 장력평가에 적절하지 않음을 알 수 있었다. 텐던의 장력 추정에 적절한 방법은 양단고정 경계조건과 휨강성을 고려한 단단한 현의 공식에 의한방법임을 알 수 있었으며, 이 방법을 실제 공용중인 PC 교량의 외부텐던에 적용한 결과 방향전환블록에 의한 마찰력으로 긴장단과 고정단에 텐던의 장력 차이가 발생한다는 것을 알 수 있었다.