For experimental studies on the production of MR fluid for MR dampers, MR fluid with a viscosity of 506 cP and a density of 2.6 g/cc was produced. In order for MR fluid to have suitable performance for MR dampers, it is important to select surfactants, magnetic particles, base oil, and characteristic additives to obtain high damping force and maintain physical and chemical properties. In order to investigate the redispersibility of MR fluid, viscosity, density, saturation magnetic flux density, dispersibility, and temperature effects were evaluated. A particle size distribution meter and a vibrating magnetometer were used, and a yield stress and redispersion device were developed to obtain the yield stress of the MR fluid. The recovery rate of MR fluid was approximately 97% at 0.2% succinic acid coating and 8% anti-settling agent. And when current is applied, the viscosity increases by more than 90% due to magnetic properties.

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.

In order to understand the MR fluid flow in the MR damper core, the annular orifice path was simplified into a square channel and the electromagnetic flow was analyzed. For this purpose, the CFD-ACE+ program was used. The temperature and magnetic field of the MR fluid were based on room temperature and orifice wall data, and 2-D steady incompressible laminar flow was assumed. The inlet and outlet of the orifice channel are at atmospheric pressure, and the inflow velocity of the MR fluid is 0.1 m/s. After analyzing the magnetic field of the core, which is a simple model of the 1 stage MR damper, the electromagnetic flow analysis of the MR fluid flowing through the orifice channel was performed. From this, the magnetic field of the orifice channel and the electromagnetic flow of the MR fluid were observed. As the magnetic flux density increased, the flow distribution and velocity of the MR fluid in the channel core changed significantly.

In the present study, the inertial electromagnetic actuator (IEA) and the FxLMS (filtered-x least mean square) method were applied to study vibration control using the active mount. IEA was designed and manufactured for the experiment, and FxLMS algorithm was developed to evaluate control performance and mount dynamic characteristics. For the vibration control experiment, active mounts were installed at the top and bottom, and the lower active mount controls the force transmitted to the structure by the excitation signal from the upper active mount. The experiment was performed by simultaneously exciting three frequencies in three axes. From the experimental results, it was confirmed that the force measured at the lower active mount when the actuator is off is greatly reduced when the actuator is on, and that vibration reduction in the vertical z-axis is more effective than vibration reduction in the x-y plane.

성별, 직업, 성품, 생활양식이 전혀 다른 K43과 C45환자의 위 내시경적 소견과 치료방법을 논의하였다. K43은 잘못된 식습관과 스트레스에 의한 미란성 위염환자로서 제산제와 함께 H_2-수용체 길항제, H^+/K^+-pump 억제제, prostaglandin 제제, colloidal bismuth, sucralfate, prokinetics 등 전통적인 약물에서부터 부작용을 감소시킨 최근에 개발된 약물에 이르기까지 효과가 인정된 약물들을 폭넓게 사용하였으나 증상을 개선치 못하였으며, 임상병리 검사와 상복부 초음파 검사는 정상이었으나, 소화생리기능 검사에서 visceral hypersensitivity를 나타내었다. 그러나 C45는 평소에 두통으로 NSAIDs를 습관적으로 복용한 경험에 의하여 발생되었을 것으로 추정되는 전형적인 위·십이지장 궤양의 환자로서 H. pylori 박멸제와 함께 일반적인 소화성 궤양이 치료제로 활동기에서 치유기로 증상을 크게 완화시켰다. 특히 K43은 amitryptyline을 투여하였으나 난치성 환자로 남아 있다. 이러한 원인불명의 비궤양성 환자는 미국에서 해마다 15%씩 증가하는 추세에 있고 적절한 치료법도 없으며, 우리 나라에서는 통계치도 없는 실정인 점을 지적하고 싶다.