• 한국산학기술학회논문지
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• 제13권5호
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• pp.2390-2395
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• 2012

지진의 영향으로 인한 지각변동 모니터링은 지구물리 및 측지학 분야에서 중요한 연구대상이다. 본 연구에서는 지난 3월 11일 오후 2시 46분 경 발생한 일본 지진에 따른 지각변동 영향을 분석하기 위해 일본지역의 9개 IGS 상시관측소를 대상으로 지진 발생 전 후의 자료를 정밀절대측위로 처리하고, 상시관측소의 위치 해석을 통해 지진으로 인한 일본지역의 지각변동을 분석하였다. 지각변동 모니터링 결과, 일본지역의 지진 변위량과 지진 전 후 지각 변동의 변화를 정량적으로 제시할 수 있었다. 지진 전 후 일본지역의 지각변동이 기존과 다른 양상을 나타내고 있음을 볼 때, GPS 관측자료 해석을 통한 지속적인 지각변동 모니터링이 필요할 것이다.

• Geomechanics and Engineering
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• 제9권3호
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• pp.275-286
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• 2015

A new method is presented to recover missing deformation data of lateral walls of foundation pit when the monitoring is interrupted; the method is called Dynamic Mathematical Model - Parameter Interpolation. The deformation of lateral walls of foundation pit is mainly affected by the type of supporting structure and the situation of constraints, therefore, this paper mainly studies the two different kinds of variation law of deep horizontal displacement when the lateral walls are constrained or not, proposes two dynamic curve models of normal distribution type and logarithmic type, deals with model parameters by interpolating and obtains the parameters of missing data, then missing monitoring data could be Figured out by these parameters. Compared with the result from the common average method which is used to recover missing data, in the upper 2/3 of the inclinometer tube, the result by using this method is closer to the actual monitoring data, in the lower 1/3 part of the inclinometer tube, the result from the common average method is closer to the actual monitoring data.

• Smart Structures and Systems
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• 제11권4호
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• pp.331-348
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• 2013

Effective monitoring, reliable data analysis, and rational data interpretations are challenges for engineers who are specialized in bridge health monitoring. This paper demonstrates how to use the Global Positioning System (GPS) and accelerometer data to accurately extract static and quasi-static displacements of the bridge induced by ambient effects. To eliminate the disadvantages of the two separate units, based on the characteristics of the bias terms derived from the GPS and accelerometer respectively, a wavelet based multi-step filtering method by combining the merits of the continuous wavelet transform (CWT) with the discrete stationary wavelet transform (SWT) is proposed so as to address the GPS deformation monitoring application more efficiently. The field measurements are carried out on an existing suspension bridge under the normal operation without any traffic interference. Experimental results showed that the frequencies and absolute displacements of the bridge can be accurate extracted by the proposed method. The integration of GPS and accelerometer can be used as a reliable tool to characterize the dynamic behavior of large structures such as suspension bridges undergoing environmental loads.

• Journal of Welding and Joining
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• 제1권2호
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• pp.69-75
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• 1983

Both in-process quality control and reliability of the weld is one of the major concerns is applying friction welding. No reliable nondestructive monitoring method is available at present to determine the weld quality particularly in process of production. So that, this paper presents an experimental examination and quantitative analysis for the effects of initial acoustic emission(AE) counts on the weld strength relating to the rotating speed as a new approach which attempts finally to develop an on-line quality monitoring system design for friction welds using AE techniques. As one of the important results, it was well confirmed that the initial AE counts occurring during plastic deformation period of welding were quantitatively correlated with reliability at 95% confidence level to the joint strength of welds, tube-to-tube (SM 20 C to STS 304) and then an AE technique using the initial AE counts can be reliably applied to in-process strength monitoring of the weld.

• Geomechanics and Engineering
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• 제11권1호
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• pp.41-58
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• 2016

This paper focuses on the deformation behavior of tunnels crossing a weak zone in conventional tunneling. A three-dimensional finite element model was adopted that allows realistic modeling of the tunnel excavation and the support installation. Using the 3D FE model, a parametric study was conducted on a number of tunneling cases with emphasis on the spatial characteristics of the weak zone such as the strike and dip angle, and on the initial stress state. The results of the analyses were thoroughly examined so that the three-dimensional tunnel displacements at the tunnel crown and the sidewalls can be related to the spatial characteristic of the weak zone as well as the initial stress state. The results indicate that the effectiveness of the absolute displacement monitoring data as early warning indicators depends strongly on the spatial characteristics of the weak zone. It is also shown that proper interpretation of the absolute monitoring data can provide not only early warning for a weak zone outside the excavation area but also information on the orientation and the extent of the weak zone. Practical implications of the findings are discussed.

• 한국측량학회지
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• 제16권1호
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• pp.27-40
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• 1998

본 논문은 구조물의 변형과 거동의 모니터링에 GPS 측위기술의 적용가능성을 제시한다. 첫번째 부분은 GPS관측의 반복재현성(repeatability)에 대한 정량적 연구로서 기준망내 기준점들간의 기선벡터를 반복적으로 측정함에 있어서 동일한 결과가 얻어질 수 있는가를 구명하고자 하였으며, 두번째 부분은 한 점당 몇 분이내의 관측시간이 소요되는 kinematic GPS측량의 변형 모니터링 수행성을 평가하고자 하였다. 흙댐을 대상으로 계절 및 수위정도에 따라 총 4차에 걸쳐 모니터링 시험망에 대한 관측을 수행하였다. 기준망은 static 방식으로 관측하였고, 모니터링 점들에 대해서는 kinematic방식은 물론 static 및 rapid-static방식으로 각각 관측을 행하여 종래의 측량기법으로 얻어진 결과와 비교하였다. 기준점들간의 기선벡터 관측에서 평균 7 mm 이내의 3차원 기선벡터의 반복재현성을 성취할 수 있었으며, 기준망들의 폐합오차는 4∼27 ppm를 나타내었다. kinematic 접근법은 종래의 측량기법에 비하여 기준점들과 모니터링 점들간의 경사거리에서 34 m의 차를 나타내었고, 높이에서는 4∼8 mm의 차를 나타내었다. kinematic GPS 측량기법은 5 m정도의 측정능력을 지닌 종래의 측량기법에 의한 변형 모니터링의 효율적인 대안이 될 수 있음을 확인할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.671-686
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• 2020

Due to the long training time and high training cost of traditional surgical training methods, the emerging virtual surgical training method has gradually replaced it as the mainstream. However, the virtual surgical system suffers from poor authenticity and high computational cost problems. For overcoming the deficiency of these problems, we propose an optimized model for the local compression deformation of soft tissue. This model uses a simulated annealing algorithm to optimize the parameters of the soft tissue model to improve the authenticity of the simulation. Meanwhile, although the soft tissue deformation is divided into local deformation region and non-deformation region, our proposed model only needs to calculate and update the deformation region, which can improve the simulation real-time performance. Besides, we define a compensation strategy for the "superelastic" effect which often occurs with the mass-spring model. To verify the validity of the model, we carry out a compression simulation experiment of abdomen and human foot and compare it with other models. The experimental results indicate the proposed model is realistic and effective in soft tissue compression simulation, and it outperforms other models in accuracy and real-time performance.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.275-291
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• 2019

In a super-large underground with "large span and high side wall", it is buried in mountains with uneven lithology, complicated geostress field and developed geological structure. These surrounding rocks are more susceptible to stability issues during the construction period. This paper takes the left bank of Baihetan hydropower station (span is 34m) as a case study example, wherein the deformation mechanism of surrounding rock appears prominent. Through analysis of geological, geophysical, construction and monitoring data, the deformation characteristics and factors are concluded. The failure mechanism, spatial distribution characteristics, and evolution mechanism are also discussed, where rock mechanics theory, $FLAC^{3D}$ numerical simulation, rock creep theory, and the theory of center point are combined. In general, huge underground cavern stability issues has arisen with respect to huge-scale and adverse geological conditions since settling these issues will have milestone significance based on the evolutionary pattern of the surrounding rock and the correlation analyses, the rational structure of the factors, and the method of nonlinear regression modeling with regard to the construction and development of hydropower engineering projects among the worldwide.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1065-1066
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• 2010

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.93-100
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• 2007

During tunnel excavation, drawdown of groundwater table or discharge from tunnel faces may not only reduce stability of tunnel and work efficiency but cause environmental problems. We have investigated the applicability of electrical resistivity survey for the establishment of the monitoring system for groundwater behavior and detecting flow channel of groundwater during tunnel excavation. The groundwater level was continuously measured at several points for 1 year. Survey was conduted at every 3 months using preinstalled electrical resistivity cables on site. The results show that observed changes in resistivity ratios in the area can be explained with observed changes in groundwater level. Thus, we believed that electrical resistivity analysed together with groundwater data can be applied for the monitoring of groundwater in tunnel area.