Earticle

본 연구에서는 지속하중에 의한 장기처짐으로 손상될 수도 또는 안 될 수도 있는 비구조요소들을 지지하 는 1방향 고강도철근(fy = 690MPa) 콘크리트 슬래브에 대하여 설계기준의 최대허용처짐을 초과하지 않는 최소두 께 값을 l/h로 계산할 수 있는 결정론적 모델을 개발하고 변수분석을 수행하였다. 결과로서 현 설계지침의 최소두 께는 가장 보수적인 설계범위 조건에서 얻어진 결과값과 비교해서 평균적으로 최대허용처짐 l/240의 경우 약 37%, l/480의 경우 약 8% 과대평가 되어있다. Ie/Ig의 범위는 l/240의 경우 0.3∼0.35, l/480의 경우 0.34∼0.46으 로 처짐제한이나 지지조건에서 큰 차이는 없었다. DL/LL에서는 l/240의 경우 1.08∼2.44, l/480의 경우 1.39∼2.86 으로 나타내고 있는데 처짐제한을 보다 엄격하게 제한하는 경우와 양단의 강성이 약한 지지조건에서 상대적으로 최소두께의 증가로 이어져 고정하중이 다소 커지는 것을 알 수 있다.

In this study, the deterministic model which can calculate minimum thicknesses as l/h, not exceeding the maximum permissible deflection, for one-way concrete members with high-strength bars (fy = 690MPa) supporting to nonstructural elements likely or not likely to be damaged by long-time deflections due to the sustained load was developed and the parametric study was performed. As a result, the minimum thicknesses of current design guide are, on average, overestimated by about 37% for l/240 and about 8% for l/480, which are the maximum allowable deflections, comparing to the results from the most conservative range of design conditions. The range of Ie/Ig is 0.3∼0.35 for l/240 and 0.34∼0.46 for l/480 which the big difference is not shown in the conditions of deflection control and support . The ratio of DL/LL presents 1.08∼2.44 for l/240 and 1.39∼2.86 for l/480, which are resulted in a little increment of dead load from the increase of minimum thickness in the tighter deflection control and weaker support condition.

This study proposes the compensation method for the mechanical deflection error of a SCARA robot. While most studies on the related subject have dealt with the development of a control algorithm for improvement of robot accuracy, this study presents the control method reflecting the mechanical deflection error which is predicted in advance. The deflection at the end of the gripper of SCARA robot is caused by the self-weights and payloads of Arm 1, Arm 2 and quill. If the deflection is constant even though robot’ posture and payload vary, there may not be a big problem on robot accuracy because repetitive accuracy, that is relative accuracy, is more important than absolute accuracy in robot. The deflection in the end of the gripper varies as robot’ posture and payload change. That’ why the moments ,  and  working on every joint of a robot vary with robot’ posture and payload size. This study suggests the compensation method which predicts the deflection in advance with the variations in robot’ posture and payload using neural network. To do this, I chose the posture of robot and the payloads at random, found the deflections by the FEM analysis, and then on the basis of this data, made compensation possible by predicting deflections in advance successively with the variations in robot’ posture and payload through neural network learning.

A computer based iterative algorithm for one-way GFRP concrete members is developed to the member thickness required to produce a computer deflection that satisfies maximum permissible deflections over a range of design conditions. The algorithm accounts for effects of cracking and long-term deflection due to creep and shrinkage. The calculated are compared with minimum thickness values based on ACI 318-05 allowable span-depth ratios based on the deterministic model. Recommendation are made for modify the current ACI 440.1R-01 provisions for minimum thickness.

In this study, we developed a device that can remotely change the deflection angle during the wind tunnel test by installing the small motors and a driving mechanism to set the angle of control surface for the missile. The torque of the motor required during the wind tunnel test is 0.6 Nm, and the maximum diameter of the motor is 20 mm. The motor can controled the angle within ±0.1 degree. After designing and manufacturing the device, the dummy weight was applied to confirm the driving torque and control requirements of the system.

In this paper, an experimental study on the control of the plume deflection panel(PDP) with a support jack of the ground launching platform using a tilt angle sensor is described. To overcome the disadvantages of the existing PDP control without a support jack using a limit sensor, the control algorithm using a tilt angle sensor and the ferroelectric RAM in the Launcher Control Unit for recognizing the contact with the ground in an abnormal operation is proposed to control the PDP in various operation environments. Finally, the proposed algorithm can be well applied for not only heavy-load launching platforms but also any other similar systems.

In this paper, we investigate path compensation scheme for the machining errors due to tool deflection in 2D contour machining. The significance of the deflection error is first shown by experiments, and a direct compensation scheme is sought. In the presented scheme, the tool path is evaluated and correcte based on the instantaneous deflection force model, until the desired contour can be obtained under the presence of tool deflection in actual machining. In the sense that the developed method estimates and compensates the machining errors via modifying the tool path, it is distinguished from the previous approach based on geometric simulation and cutting simulation. Further, it can be viewed as a direct and active method toward direct shape control in CNC machining. Simulation results are included to show the validity and adequacy of the path-modification scheme under various cutting conditions.

An indoor package air-conditioner (PAC) has complex noise sources such as motor noise and fluid noise caused by the fan motor, heat transfer and shroud. Sound intensity techniques and ODS(Operational deflection shape) techniques are applied to identify the noise characteristics of an indoor air-conditioner's cabinet. The sound intensity is used to visualize the noise source locations. and the ODS to visualize the vibration pattern and to obtain the dynamic characteristics of the noise source. Acoustic intensity and operational deflection distribution are obtained in space domains as well as frequency domains. Using the visual information of source locations and its dynamic characteristics, the damping patch is applied to reduce structure borne noise in the cabinet. As a result, the noise emitted by the cabinet is reduced by 5dB.