• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.578-581
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• 2007

In this study, the seismic control performance of energy dissipation devices installed in a shear all-frame structure is investigated through nonlinear time history analysis of a 12-story building. Inelastic shear walls are modeled using the multiple vertical line element model (MVLEM) and inelastic columns and girders were modeled using fiber beam elements. For a seismic load increased by 38% compared to the design load, the seismic control performance was analyzed based on the results of a nonlinear time history analysis in terms of the inter-story drift, the story shear and the flexural strain. Friction type dampers was found to performs best if they are installed in the form of a brace adjacent to the shear wall with the friction force of 15 % of the maximum story shear force induced in the original building structure without dampers.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.16-22
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• 2014

Automotive NVH on brake operation is mainly caused by a coupling action of vehicle speed and inter parts friction and its frequency occurs over a broad band of 0.1 kHz~10 kHz. Especially, squeal noise, being a self-excited vibration generated by friction force between drum and lining, occurs over 1 kHz and consequently dynamic instability is induced when friction energy is applied to a brake vibration system. The squeal strongly depends on nonlinear properties influenced by the material of lining, velocity of vehicle, and the dynamic properties of a brake system. The dynamic properties are considered as a main influential design factor to squeal noise, however the analysis of the properties are rarely facilitated due to arbitrariness of shape by wearing down. In this paper, we research generating tendency of squeal noise through complex eigenvalue analysis, tracking drum brake's unstable modes in accordance with the wear shape of drum and lining such as tapered and bellmouth shape, and analyze computed unstable modes by variable shapes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.996-1001
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• 2006

Automatic washing machines have been improved and popularized steadily since the first electric washing machine was produced in the early 1900's. Appliance industry has tried to obtain the performance of washing machine with large capacity, high energy efficiency, low vibration and low noise levels. As the installation peace of a washer becomes closer to the living space, vibration and noise problems become more important challenges. In general, a washing machine has four legs to support its body. Four legs of the washing machine should be attached on a floor. If not so, it may cause severe vibration or walking in the spin-drying process. Unfortunately, the floor of an ordinary house is bumpy in general, and the consumers will not accept bolting washing machines to a foundation; moreover, sometimes they move the location of their washing machines to utility rooms or bath rooms or kitchens and don't care for leveling the legs exactly. In this study, we devise an auto-leg system that prevents the occurrence of abnormal vibration and walking of washing machines. It is simply composed of a spring and a friction damper. Some experiments are implemented to show the dynamic characteristics of the three-dimensional auto-legged washing machine model that is located on the even or uneven ground. A spring parameter is optimized to adjust the length of the auto-leg system automatically up to 10 mm irregularity, and the friction damper is designed to decrease a resonance induced by the spring of the auto-leg system. Some numerical results show that placing the proposed auto-leg system in a washing machine makes good performance with low vibration, as well as low noise, regardless of the unevenness of the floor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.181-184
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• 2014

Loose Parts Monitoring System(LPMS) monitors loosened or detached parts and foreign parts inside the pressure boundary of a reactor coolant system (RCS). It is difficult to discriminate valid signal from LPMS alarms at full power since the signal pattern by thermal shocks and structure friction are similar to those by loose metal impacts. In addition, It is more difficult to discriminate the impact signals induced by the rod driving, sensor hard-line movement and loosened component since they have similar frequency characteristics with valid signals. This paper classifies the signal patterns by analyzing actual LPMS signal captured during nuclear power plant operation.

• 한국소음진동공학회논문집
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• 제15권8호
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• pp.975-979
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• 2005

The analysis of a mechanical system, body traveling along the elastic structure, has been a topic of interest. The establishment of analytical method for the development and control of this system is required in the fields of many machine operations such as modern weapons and high-speed feed drive system for a machine tool. The dynamic equations are derived on the torsion of a cantilever hollow shaft induced by the spin-up of a moving mass and the displacement of the mass. Influences of design parameters such as the inertia ratio, the mass moving speed and the friction coefficient are discussed on the transient response of the system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1789-1794
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• 2004

The present study investigates flow characteristics in an optical disc drive. Detailed knowledge of the flow characteristics is essential to analyze flow-induced noise and vibration, forced convection and flow friction loss. The ODD used in the personal computer is used for the experiment and rotating velocity of disc is under the 4500 rpm. Time-resolved velocity components and velocity spectrum are obtained using the laser Doppler anemometry (LDA). The results show that the front holes reduce now-induced noise and the position of pickup body affects flow near the window. In addition, il is possible for cooling of heat sources in an optical disc drive through measuring the flow fields under the tray.

• 대한기계학회논문집
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• 제8권6호
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• pp.591-598
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• 1984

본 논문에서는 고체상호간 미끄름접촉에 의해 발생하는 진동과 소음의 특성을 조사하기 위해서 실험과 이론해석을 행하였다. 미끄름접촉과 관련된 소음에는 brake squeal 혹은 wheel screech등과 같이 stick-slip 형태의 동적 불안정 상태와 관련이 있는 squeal noise와, 겉보기로 동적 안정 상태에 있으나 미끄름접촉면간에 내재하는 미끄름접촉 고유의 불규칙한 동특성에 기인하여 발생하는 rubbing noise가 있다. 본 연구의 대상은 보다 기본적인 형태인 후자에 한한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.452-458
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• 2007

The vertical extension of a building in general remodeling process increases both gravity and seismic loads by simply adding masses to the building. In this study, a vertical extension structural module (VESM) is proposed for enhancing seismic performance of the existing buildings by utilizing the story-increased parts. The proposed VESM is composed of steel column, steel beam, and beam-end rotational damper. The steel columns are connected to the shear walls and transfer the wall rotation in out-of plane to the steel beam, and then the beam-end rotational damper dissipates the earthquake-induced energy. Numerical analysis result from a cantilever beam of which end-rotation is restricted by rotational damper indicates that the displacement, base shear, and base overturning moment of the existing structures showing cantilever behavior can be significantly reduced by using the proposed method. Also, it is observed that friction-type rotational damper is effective than viscous one.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.472-472
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• 2009

The safety of cultural properties, medical treatment and electrical communication equipments in a building was hardly considered against the earthquake induced vibration, while the integrity of the building structure has been taken into account through the resistant earthquake design. This paper presents design of a seismic isolation table for both indoor and outdoor electrical communication equipment. First of all, artificial earthquake waves compatible with floor and ground response spectra for electrical communication equipments are generated using previously recorded seismic waves. Two kinds of one-degree-of-freedom seismic isolation table systems: spring-linear damper and spring-friction damper systems are considered and their responses to artificial earthquake waves are simulated. Design parameter study for two seismic isolation tables are performed through simulations and a seismic isolation table for both indoor and outdoor electrical communication equipment is designed considering the simulation results.

• 한국소음진동공학회논문집
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• 제22권11호
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• pp.1078-1088
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• 2012

Recently, the vibration and structure-borne noise induced by passing trains are of great concerns, and the floating slab track is highlighted as one of most efficient alternatives to reduce the railway vibration. However, due to the non-linearity and viscosity of rubber spring used in the floating slab track, its dynamic behavior is very complex. In this study, therefore, to simulate the dynamic behavior of floating slab track with a better accuracy, a nonlinear viscoelastic rubber spring model that can be incorporated in commercial finite element analysis codes has been proposed. This model is composed of a combination of elastic spring element, friction element and viscous element, and termed the "generalized friction viscoelastic model(GFVM)". Also, in this study, the method to determine the model parameters of GFVM based on Berg's 5-parameter model was presented. The results of the finite element analysis with this rubber spring model exhibit very good correlation with the test results of a laboratory mock-up test, and the feasibility of GFVM has been verified.