Accompanied with the industrial development, and enlarging and heightening buildings, building equipments are also enlarging. These changes are serious to the cause of structure noises. The Floating Floor System which uses the soft foam polyurethane are becoming popular in construction areas for its short construction period and well vibration proof ability, hence it is becoming wide in the marketing volume. We were able to enhance the physical characteristics of the vibration proof polyurethane mat with this study. As a result, we were also able to secure material competitiveness by meeting the requirements of customer satisfaction through enhancement in estimated material lifetime and physical characteristics.

Large space structures exhibit different natural vibration characteristics depending on the aspect ratio of structures such as half-open angle. In addition, since the actual large space structure is mostly supported by the lower structure, it is expected that the natural vibration characteristics of the upper structure and the entire structure will vary depending on the lower structure. Therefore, in this study, the natural vibration characteristics of the dome structure are analyzed according to the natural frequency ratio by controlling the stiffness of the substructure. As the natural frequency of the substructure increases, the natural frequency of the whole structure increases similarly to the natural frequency of the upper structure. Vertical vibration modes dominate at 30° and 45°, and horizontal vibration modes dominate at 60° and 90°.

Since the 2010 year, an occurring number of grand scale earthquakes which above magnitude 5.0 have increased in the world. Many types of research that deal with reducing the damage to the structure from a large-scale earthquake have proceeded. A system which could mitigate strong vertical earthquake's acceleration might apply to structure, since big earthquake cases that occurred lots of loss in Tokyo and Kobe of Japan. A plenty of bearings have installed to mitigate vibration but many parts of these lack efficient ability what we want. In addition, former vertical isolation bearings to apply for the structure have both price and size limits according to material characteristics. Therefore, this paper proposes a new type of device that is made by utilized engineering plastic and improves hitherto used vertical isolation bearing's fault.

In commercial vehicles. the pulsation noise when the power steering operating is the major item to make the complain for users. If this noise have related to vibration characteristics in steering system's parts or assembly, it makes the problem in vehicle quality. Recently, the users demand the high quality in commercial vehicles, and we must identified the relevance between the pulsation noise and the vibration characteristics. After the identification, we can design the power steering system for satisfaction the user’s needs. Finally, the identification of relevance in pulsation noise for analysing the vibration characteristics will be suggested advanced power steering system.

본 논문에서는 Co-Rotational plane beam transient analysis EDISON program(CR-보)를 이용한 에어포일 단면형상 변화 에 따른 진동특성 연구를 수행하였다. Co-Rotational 평면 보 해석은 대 회전과 작은 변형률을 갖는 보 해석에 적합하다. 항 공기의 날개를 외팔보로 가정하여, VABS를 통한 단면해석과 Fourier 변환을 통해 각 단면형상 변화에 따른 에어포일의 고 유진동수를 비교하였다. VABS를 사용하여 단면의 형상과 재료의 적층 정보를 고려한 단면에서의 유한요소 해석을 수행하 였다. 에어포일의 재질, spar 유무, 단일 등방성 재료·복합재료, 에어포일 최대두께의 변화에 따라 에어포일의 끝단 진폭과 고유진동수가 변화함을 확인할 수 있었다. 이를 바탕으로 에어포일 고유진동수 변화는 2차 관성모멘트/단면적, 밀도, 영률의 변화에 상당한 영향을 받음을 알 수 있었다.

With the recent trend to construct high-rise and large buildings, the steel structure system is widely used, but there are not enough studies on the vibration characteristics of the iFLASH system on the buildings. Therefore, in this study, we performed a vibration measurement of the natural frequency and damping ratio in the stage of iFLASH panel, composit, frame completion and cladding completion. The result findings suggest that the damping ratio after the cladding completion has a greater effect on the reduction of the damping ratio, than the stage after the frame completion.

In this study, natural frequency characteristics of road mower head system are investigated through experiment and numerical analysis. ANSYS workbench 14.5 is used to calculate the frequency analysis in the mower system. Compared the natural frequency using the modal test and computerized analysis. When compared with the experimental results, a 5% error rate has occurred. Simulation results showed that vibration mode shape has directional characteristics, especially to the right and left. These results will be helpful in optimal design for road mower head systems.

The tires changes characteristics of the element constituting change. Stiffness is one of the various characteristics of the tire. Stiffness of the tire is change contact contour. it is known to affect vibration and noise of the vehicle. In this study we conduct to find influence of change stiffness of the tire due to vibration characteristics inside passenger car. For this study we choose tires of available on the market and measure vertical spring rate and lateral spring rate. Also through the real passenger car we find vibration characteristics in the inside of car. In conclusion, vibration energy is reducing with increase in the stiffness and we find the high vibration level of low frequency band in passenger car due to decreasing stiffness.

The train noise and vibration nearby the elevated railway make one specific issue. For the elevated railway, this paper concerns vibration by the bridge. this paper presents vibration level of vibration source of train. The prediction model gives the effects of ground attenuation, and barrier attenuation of noise. The acceleration array method is used to search vibration propagation characteristics of elevated structure to predict the vibration propagation from an elevated railway. Based on the results, this paper proposes the source model of elevated structure-borne vibration and the calculation model for elevated railway vibration. Also measure results are presented with rolling vibration and elevated structure vibration.

In this paper, the vibrational characteristic of electronic solenoid structure for vehicle is analyzed by using ADAMS as commercial multi-body dynamics analysis program. This study model is made with CATIA V5R18 as 3D computer-aided design program and analyzed with rigid body mode in ADAMS. To fulfill the vibration analysis, the result value of solenoid structure is suggested.

Recently, the quiet fan development is one of important issues for comfort of railroad car. The purpose of this study is to find the vibration and noise source of the line flow fan for reduction the noise level. For a vibration and noise source identification, experiments with microphone and acceleration were carefully carried out. The noise of line flow fan is caused by various factors, such as turbulent flow noise, blade passing frequence and unbalance. In order to reduce the fan noise, the blade shape, distance and angle of housing guide should be modified.

본 연구에서는 39층 테크노마트의 태풍시 진동응답을 계측하고 이로부터 건물의 동적특성을 평가하였다. 2011년 태풍 무이파가 우리나라를 통과할 때 건물의 38층의 가속도 응답을 계측하였으며, 계측신호를 이용하여 구조물의 고유진동수 및 감쇠비등을 독립성분분석법을 사용하여 구하였다. 독립성분분석법을 통해 매우 유사한 크기를 가지는 장변방향 및 단변방향 진동모드를 분리할 수 있었으며, 분리된 모드를 사용하여 각 모드에 해당하는 감쇠비를 추출할 수 있었다. 또한, 하중과 슬래브-보의 합성효과 등을 고려하여 구조해석모델을 개선하여, 개선된 모델이 실제 계측한 진동수 및 감쇠비와 유사한 값을 가지도록 하였다.

Heunginjimun as treasure No.1 is wooden structure of 2 story. This stucly presents an investigation on vibration characteristics of Heunginjimun in Seoul through ambient vibration test. The research team studied structural characteristics unlike general building and performed the test. Natural or environmental excitation as ambient vibration source is always present and hence the test implies a minimum interference with normal use of the structure. Natural frequencies, damping ratio and modes are identified and compared using two strategies, Frequency Domain Decomposition, Stochastic Subspace Identification techniques. The result shows that behavior and dynamic property of Heuninjimun.

구조물이 건전한 상태에서 진동계측을 통한 고유진동수와 감쇠율과 같은 동적특성의 분석에 대하여 국내 외적으로 많은 연구가 진행되어 왔다. 그러나 실물 구조물에 대하여 파괴 직전까지의 큰 손상 후에 진동계측을 통한 동적특성에 대한 연구는 상대적으로 매우 미약한 실정이다. 따라서 본 연구는 3층 철근콘크리트조 건물에 엑츄에이터로 하중을 주어 건물에 손상을 준 후에 손상 전 후의 진동계측을 통하여 동적특성을 파악하였다. 손상 전 후에 대한 고유진동수 및 감쇠율을 산정하였으며, 이 결과를 국외의 기존 연구와 비교하였다. 상시진동계측 및 인력가진을 통한 계측방법을 실시하였으며, 계측 전에 고유치 해석을 선행하여 계측치와 비교분석을 하였다. 120mm의 수평변위를 준 결과 구조물의 파괴 직전 손상 전 후에 장변과 단변의 고유진동수는 각각 34.3%, 33.7% 감소하였고, 감쇠율은 각각 36.5%, 19.5% 감소하였다. 기존 국외의 연구결과와의 비교를 한 결과 고층형 건물보다 강성의 변화가 크게 감소됨을 확인할 수 있었으며, 저층형 구조물에 대한 안정성 검토가 시급함을 확인할 수 있다.

LCVA has an advantage that its natural frequency can be easily controlled by changing the area ratio of the vertical column and horizontal part. The previous studies investigated the dynamic characteristics of the LCVA under harmonic load. This study experimentally obtained the first and second mode natural frequencies of the LCVA from shaking table tests using white noise and compared the values with the ones by previous study. Test results show that the measured first mode natural frequency of the LCVA is larger than the calculated one when the area ratio is larger than 1. The second mode frequency increases with the increasing area ratio, which is due to the sloshing motion effect resulting from the large area of the vertical column.

본 연구는 경북지역에 존재하는 보물급 이상의 석탑을 대상으로 바람이 석탑 상륜부에 미치는 영향의 정도를 확인하기 위한 연구이다. 연구모델은, 현재까지 경북지역 석탑 상륜부에 대한 실측자료가 없다는 점, 경주 석가탑 상륜부를 포함하여 복원된 석탑 상륜부의 원형 모델이 실상사삼층석탑이라는 점 그리고 이것은 최근에 실측된 자료가 있다는 점을 고려하여, 완전하게 남아있는 우리나라의 몇 안되는 탑 중 하나인 남원 실상사동(東)삼층석탑으로 선정하였다. 연구내용은 경북지역 기상관측자료를 분석하여 설계풍속을 설정하는 것, 이에 근거하여 상륜부에 작용하는 최대전 도모멘트를 산출하고 상륜부의 정적 안정성을 검토하는 것과 와류 방출(vortex shedding)에 의한 와류진동 발생 가능성을 판단하는 것으로 하였다. 1/6 크기의 실험모형을 제작하여 풍력실험을 수행하였다. 기본설계풍속은 울릉도를 제외 한 경북지역 각 관측점에서 300년 재현주기 풍속을 넘는 35m/s를 적용하였다. 상륜부의 밑면에서 전도모멘트에 의한 허용응력 초과의 가능성을 판단하였다. 원형 단면에 대한 스트로할 수(Strouhal number)를 기준으로 공진의 가능성을 판단하였다.