• Journal of the Korean Society of Hazard Mitigation
• /
• v.6 no.3 s.22
• /
• pp.17-28
• /
• 2006

Structural health monitoring is important to maintain the safety and serviceability of the structures. The displacement in the structure should be precisely and frequently monitored because it is a direct assessment index indicating its stiffness. However, no practical method has been developed to monitor such displacement precisely, particularly for high-rise buildings and long span bridges because they cannot be easily accessible. To overcome such difficult accessibility, we propose to use a LIDAR system that remotely samples the surface of an object using laser pulses and generates the coordinates of numerous points on the surface. In this study, using terrestrial LiDAR, we develop a novel displacement measuring model for structural health monitoring and perform an indoor experiment to prove its performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.05a
• /
• pp.83-86
• /
• 1994

On this paper, the structural changes of molecules on the water surface were monitored by the measuring system of displacement currents. The measuring system was constructed at home-made Kuhn type LB(Langmuir -Blodgett) deposition apparatus. Solutions of 4-octyl -4\\`- (5-car boxy$.$ -pentamethyleneoxy) azobenzene molecules (8A5H) and stearic acid(C$\_$18/) were spreaded at the air-water interface respectively, and the currents inducted by the dynamic behavior of molecules were measured when the molecules were the molecules were pressed by barrier. From C$\_$18/ mo1ecules two distinct peaks of displacement currents were obtained, which show that the orientations of mo1ecules were charged largely at these Points. The reversibility of displacement currents by compression and expansion was obtained from 8A5H molecules, which shows the compressed molecules which shows the compressed molecules have a tendency to disperse after the compression. But it was not obtained from C$\_$18/ molecules which means that this molecules disperse not easily by decreasing the pressure of the barrier.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.10a
• /
• pp.677-678
• /
• 2009

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.113-117
• /
• 1995

The mechanism of the displacement current generation for stimulation transmit observed in the present displacement current measurement and theoretically analysed. The orientational change of molecules in monolayers was discussed on the basis of the Maxwell-displacement-current obtained. Maxwell displacement current was generated from monolayers on a water surface by monolayerr compression, and it measuring technique has been applied to the study of monolayers of Dipalmitoylphosphatidyl choline (L-${\alpha}$-DPPC). Finally, We measured that differential thermal analysis(DTA) of sample. Displacement current was generated when the area per molecule about 180${\AA}$$^2$in low pressure, and it was generated when the area per molecule about 110${\AA}$$^2$in high pressure. A result of DTA was showed that temperature at 124.6$^{\circ}C$.

• Journal of the Korean Wood Science and Technology
• /
• v.27 no.4
• /
• pp.51-56
• /
• 1999

Finite element method was utilized to analyze crack tip stress and displacement field under drying stress case as stepwise loading. Opening mode of single-edge-notched model was employed and analyzed by linear elastic fracture mechanics of plane stress case. The drying stresses were applied as stepwise loads at the boundary elements of the model with 10 steps of time serial. The stress intensity factor($K_I$) for opening mode reached to its maximum just prior to the stress reversal. The $K_I$ from the displacement fields revealed 1.7 times higher than those from stress fields. By comparing the two sets of $K_I$ from displacement and stress fields, single parameter $K_I$ showed its validity to characterize displacement fields around the crack tip front while stress field could not be characterized due to large variations between two sets of data.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.2 no.3
• /
• pp.194-204
• /
• 1998

This study was performed to suggest the proper maintenance method for the deteriorated gerber type PC box girder bridge by using the long term displacement monitoring data. For this study, the monitoring system which can measure the long term displacement and the concrete surface temperature was designed and operated. From the measurement and structural analysis results, the cause of the permanent deformation which the bridge has already was estimated, and based on this result, the allowable permanent displacement value at the hinge was suggested. From this study, it was known that the long term monitoring system can be applied to the active maintenance of the deteriorated bridge and the suggested allowable permanent displacement could be used for the maintenance of the bridge.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2006.11a
• /
• pp.295-298
• /
• 2006

본 논문에서는 극 좌표계에서의 벡터 표현 방식을 이용한 per-pixel displacement mapping 방법을 제시한다. per-pixel displacement mapping은 triangle mesh의 처리 방식에 상관없이 변위매핑을 수행할 수 있도록 한 것으로, 2차원 screen space로 projection 된 triangle의 각 pixel의 위치를 객체 표면 정보에 따라 displacement 해주는 방법이다. 이는 기 검증된 범프매칭 하드웨어에 약간의 하드웨어를 추가함으로써 변위매핑을 수행할 수 있도록 한 효과적인 구조이다. 제안 방식에 의해 생성된 영상과 기존 방식에 의해 생성된 영상을 비교해본 결과, 시각적으로 거의 차이가 없음을 알 수 있다.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2003.03a
• /
• pp.129-139
• /
• 2003

The response displacement method is the most frequently used method for seismic design of buried structures. This method is pseudo-static method, and the evaluations of velocity response spectrum of seismic base and response displacement of surrounding soil are the most important steps. In this study, the evaluation of velocity response spectrum of seismic base according to the Korean seismic design guide and the simple method of calculating the response displacement were studied. It was found that velocity response spectrum of seismic base can be estimated by direct integrating the ground-surface acceleration response spectrum of soil type $S_{A}$, and the evaluation of the response displacement using double cosine method assuming two layers of soil profile shows the advantages in the seismic design.n.

• Proceedings of the KSRS Conference
• /
• 2008.10a
• /
• pp.418-421
• /
• 2008

Wenchuan earthquake (Mw 7.9) occurred in Sichuan province, China, May 2008 had resulted in a huge fault displacement around the Lungmenshan fault. Preliminary results of the fault displacement observed by ALOS PALSAR interferometry are presented. The surface deformation by the Wenchuan earthquake was reported up to 10m consisting of thrust- and right-slip compnents. A significant reduction in ionospheric density was also reported. Twenty differential interferograms and twenty multiple aperture SAR interferometry (MAI) pairs were produced over four ALOS tracks. It was observed from differential interferograms that i) LOS deformation decreases steadily from northnorthwest of the Longmenshan fault to the fault, ii) the LOS deformation sharply increases at areas around the fault, and iii) the decrease of the LOS deformation is observed from the Longmenshan fault to the south-southeast of the fault. Horizontal movement of the reverse fault displacement can better be observed by MAI technique, and the MAI phases show that i) the south-southeast directional reverse fault displacement (negative along-track deformation for an ascending track) of the north-northwest block gradually increases to the Longmenshan fault, ii) the reverse fault movement of the south-southeast block is sharply reversed to the north-northwest of the fault, and iii) the northnorthwest movement gradually decreases to the south-southeast of fault. Although the Lonmenshan Fault line is a center of earthquake epicenter, the boundary of surface movement exists to the north-northeast of the fault. Since the ionosphere was not stable even forty days after the mainshock, MAI phases were seriously corrupted by ionospheric effect. It is necessary to acquire more data when the ionosphere recovered to a normal state.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.5 no.4 s.19
• /
• pp.49-57
• /
• 2005

The purpose of this study is to closely examine the influence of the surcharge load applied to the retaining wall through some model tests, in which wall stiffness in each stage of excavation, horizontal displacement of the retaining wall and surface displacement of the backfill according to wall stiffness and ground conditions, and change and distribution of the earth pressure applied to it were measured and their values were produced, then these values were mutually compared with their theoretical values and their values after analysis of the data obtained at the field, and they were analytically studied, in order to closely examine the influence of the surcharge load applied to the retaining wall. Findings from this study are as follows: The shape of ground surface settlement curve on the model ground under surcharge load, different from the distribution curve of regular probabilities which is of a shape of ground surface settlement under no surcharge load, appears in that settlement in an arching shape shows where the center part of surcharge load shows the maximum settlement. In examining the maximum horizontal displacement with the surcharge load applied to each stage of excavation, it occured at the point of 0.8H(excavation depth) when finally excavated. Regarding the range in which the displacement of the retaining wall increases according to application of surcharge load, the increment of displacement showed till the point of depth which is of two times of the distance of load from the upper part of the wall. Also since each displacement of the foundation plate caused by the ground surface settlement according to each stage of excavation occured most significantly at the final stage. Also since regarding wall stiffness, the wall of its thickness of 4mm(flexible coefficient $p:480m^3/t$), produced maximum 3 times of wall stiffness than its thickness of 9mm(flexible coefficient $p: 40m^3/t$), it was found out that influence of wall stiffness is so significant.