Using a Kernel Extreme Learning Machine with Grey Wolf Optimization to Predict the Displacement of Step-like Landslide

( Kang Liao ),( Yiping Wu ),( Fasheng Miao ),( Linwei Li ),( Yang Xue ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Landslide displacement prediction is an essential topic in the landslide hazard research. Considering the characteristics of landslide deformation in the Three Gorges Reservoir Area of China, a step-like displacement prediction model based on Kernel Extreme Learning Machine with Grey Wolf Optimization (GWO-KELM) is proposed to predict the Baishuihe Landslide. First, the cumulative displacement is decomposed into the trend displacement and the periodic displacement by time series. Second, the trend displacement is predicted by a cubic polynomial model and the periodic displacement is predicted by the proposed model after statistically analyzing the displacement data. A hybrid model is then established for the prediction of landslide displacement. In addition, the performance of the hybrid model is compared with that of the Extreme Learning Machine with Grey Wolf Optimization (GWO-ELM), Support Vector Machine with Grey Wolf Optimization (GWO-SVM), and Extreme Learning Machine (ELM). The results show that the proposed hybrid model outperforms the other models, and the GWO-KELM model achieves a great ability in predicting the landslide displacement with a step-like behavior.

Multipoint variable generalized displacement methods: Novel nonlinear solution schemes in structural mechanics

Ali Maghami,Farzad Shahabian,Seyed Mahmoud Hosseini 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.2

The generalized displacement method is a nonlinear solution scheme that follows the equilibrium path of the structure based on the development of the generalized displacement. This method traces the path uniformly with a constant amount of generalized displacement. In this article, we first develop higher-order generalized displacement methods based on multi-point techniques. According to the concept of generalized stiffness, a relation is proposed to adjust the generalized displacement during the path-following. This formulation provides the possibility to change the amount of generalized displacement along the path due to changes in generalized stiffness. We, then, introduce higher-order algorithms of variable generalized displacement method using multi-point methods. Finally, we demonstrate with numerical examples that the presented algorithms, including multi-point generalized displacement methods and multi-point variable generalized displacement methods, are capable of following the equilibrium path. A comparison with the arc length method, generalized displacement method, and multi-point arc-length methods illustrates that the adjustment of generalized displacement significantly reduces the number of steps during the path-following. We also demonstrate that the application of multi-point methods reduces the number of iterations.

Characterization of Complete Radial Displacement of Tunnel Using a Horizontal Inclinometer

Chung, So-Keul,Ryu, Dong-Woo,Jang, Won-Il,Yang, Hyung-Sik 한국암반공학회 2010 Geosystem engineering Vol.13 No.2

Measuring the displacement of a tunnel is prerequisite in evaluating the stability, which also makes it possible to understand the geological condition ahead of the tunnel face. In fact, the displacement of a tunnel occurs before, during and after the excavation. Generally, the measurement is undertaken only behind the face, which allows a certain amount of displacement, the so-called 're-measurement-displacement' The measured displacement is only a part of the total radial displacement. Therefore, the pre-measurement-displacement should be determined in order to characterize the complete radial displacement of the tunnel. A horizontal inclinometer was used to measure the degree of settlement ahead of the tunnel face at the study site, which was relatively easy to install from the other portal of the tunnel. The results from the measurement of the settlement ahead of the face enabled a complete radial displacement curve to be constructed using a nonlinear regression analysis. It was found that the crown displacement of the tunnel at the study site started to occur at a distance equivalent to three times of the tunnel diameter ahead of the tunnel face. Taking into consideration the complete displacement characteristics, the possible settlement could be about 40% of the total displacement of the tunnel. Based on the complete radial displacement, it was possible to determine the appropriate support characteristics and the time of installation.

Computer vision-based remote displacement monitoring system for in-situ bridge bearings robust to large displacement induced by temperature change

Soojin Cho,Byunghyun Kim,Junhwa Lee,Sung-Han Sim,Byung Ho Park 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.5

Efficient management of deteriorating civil infrastructure is one of the most important research topics in many developed countries. In particular, the remote displacement measurement of bridges using linear variable differential transformers, global positioning systems, laser Doppler vibrometers, and computer vision technologies has been attempted extensively. This paper proposes a remote displacement measurement system using closed-circuit televisions (CCTVs) and a computer-vision-based method for in-situ bridge bearings having relatively large displacement due to temperature change in long term. The hardware of the system is composed of a reference target for displacement measurement, a CCTV to capture target images, a gateway to transmit images via a mobile network, and a central server to store and process transmitted images. The usage of CCTV capable of night vision capture and wireless data communication enable long-term 24-hour monitoring on wide range of bridge area. The computer vision algorithm to estimate displacement from the images involves image preprocessing for enhancing the circular features of the target, circular Hough transformation for detecting circles on the target in the whole field-of-view (FOV), and homography transformation for converting the movement of the target in the images into an actual expansion displacement. The simple target design and robust circle detection algorithm help to measure displacement using target images where the targets are far apart from each other. The proposed system is installed at the Tancheon Overpass located in Seoul, and field experiments are performed to evaluate the accuracy of circle detection and displacement measurements. The circle detection accuracy is evaluated using 28,542 images captured from 71 CCTVs installed at the testbed, and only 48 images (0.168%) fail to detect the circles on the target because of subpar imaging conditions. The accuracy of displacement measurement is evaluated using images captured for 17 days from three CCTVs; the average and root-meansquare errors are 0.10 and 0.131 mm, respectively, compared with a similar displacement measurement. The long-term operation of the system, as evaluated using 8-month data, shows high accuracy and stability of the proposed system.

Characterization of Complete Radial Displacement of Tunnel Using a Horizontal Inclinometer

류동우,정소걸,장원일,양형식 한국자원공학회 2010 Geosystem engineering Vol.13 No.2

Measuring the displacement of a tunnel is prerequisite in evaluating the stability, which also makes it possible to understand the geological condition ahead of the tunnel face. In fact, the displacement of a tunnel occurs before, during and after the excavation. Generally, the measurement is undertaken only behind the face, which allows a certain amount of displacement, the so-called ‘pre-measurement-displacement’. The measured displacement is only a part of the total radial displacement. Therefore, the pre-measurement-displacement should be determined in order to characterize the complete radial displacement of the tunnel. A horizontal inclinometer was used to measure the degree of settlement ahead of the tunnel face at the study site, which was relatively easy to install from the other portal of the tunnel. The results from the measurement of the settlement ahead of the face enabled a complete radial displacement curve to be constructed using a nonlinear regression analysis. It was found that the crown displacement of the tunnel at the study site started to occur at a distance equivalent to three times of the tunnel diameter ahead of the tunnel face. Taking into consideration the complete displacement characteristics, the possible settlement could be about 40% of the total displacement of the tunnel. Based on the complete radial displacement, it was possible to determine the appropriate support characteristics and the time of installation.

지진의 특성주기를 고려한 완만한 곡선형 이력거동시스템의 비탄성 변위비

송종걸 한국지진공학회 2013 한국지진공학회논문집 Vol.17 No.1

In order to predict inelastic displacement response without nonlinear dynamic analysis, the equal displacement rule can be used for the structures with longer natural periods than the characteristic period, Tg, of earthquake record. In the period range longer than Tg, peak displacement responses of elastic systems are equal or larger than those of inelastic systems. In the period range shorter than Tg, opposite trend occurs. In the equal displacement rule, it is assumed that peak displacement of inelastic system with longer natural period than Tg equals to that of elastic system with same natural period. The equal displacement rule is very useful for seismic design purpose of structures with longer natural period than Tg. In the period range shorter than Tg, the peak displacement of inelastic system can be simply evaluated from the peak displacement of elastic system by using the inelastic displacement ratio, which is defined as the ratio of the peak inelastic displacement to the peak elastic displacement. Smooth hysteretic behavior is more similar to actual response of real structural system than a piece-wise linear hysteretic behavior such as bilinear or stiffness degrading behaviors. In this paper, the inelastic displacement ratios of the smooth hysteretic behavior system are evaluated for far-fault and near-fault earthquakes. The simple formula of inelastic displacement ratio considering the effect of Tg is proposed.

상시 진동을 이용한 교량 정적 처짐 산정 기술의 현장 적용성 연구

오상혁,문대중,이광명 한국건설순환자원학회 2023 한국건설순환자원학회 논문집 Vol.11 No.4

In safety assessment of a aged bridge, dynamic characteristics and displacement are directly related to the rigidity of the structural system, especially displacement is the most important factor as the physical quantity that the bridge user can directly detect. However, in order to measure the displacement of the bridge, it is difficult to install displacement sensors at the bottom of the bridge and conduct traffic blocking and loading tests, resulting in increased costs or impossible measurements depending on the bridge's environment. In this study, a method of measuring the displacement of a bridge using only accelerometers without installing displacement sensors and ambient vibration without a loading test was proposed. For the analysis of bridge dynamic characteristics and displacement using ambient vibration, the mode shape and natural frequency of the bridge were extracted using a TDD technique known to enable quick analysis with simple calculations, and the unit load displacement of the bridge was analyzed through flexibility analysis to calculate static displacement. To verify this proposed technology, an on-site test was conducted on C Bridge, and the results were compared with the measured values of the loading test and the structural analysis data. As a result, it was confirmed that the mode shape and natural frequency were 0.42 to 1.13 % error ratio, and the maximum displacement at the main span was 3.58 % error ratio. Therefore, the proposed technology can be used as a basis data for indirectly determine the safety of the bridge by comparing the amount of displacement compared to the design and analysis values by estimating the displacement of the bridge that could not be measured due to the difficulty of installing displacement sensors.

Structural displacement estimation through multi-rate fusion of accelerometer and RTK-GPS displacement and velocity measurements

Kim, Kiyoung,Choi, Jaemook,Chung, Junyeon,Koo, Gunhee,Bae, In-Hwan,Sohn, Hoon Elsevier 2018 MEASUREMENT -LONDON- Vol.130 No.-

<P><B>Abstract</B></P> <P>For civil infrastructure monitoring, RTK-GPS sensors are commonly used to measure dynamic displacement. However, these sensors have poor precision (around 0.5–5 cm in the vertical direction) and a low sampling rate (up to 20 Hz). Furthermore, both the accuracy and the precision of the RTK-GPS sensors deteriorate when signals from satellites are not properly received by the sensors due to multipath, bad weather, signal blockage, etc. In this study, a new dynamic displacement estimation method is proposed so that the accuracy, precision, and sampling rate of dynamic displacement can be improved by combining the acceleration measured by a force-feedback accelerometer and the velocity and displacement measured by a low-cost RTK-GPS sensor. The uncertainty levels in the displacement and velocity measured by the RTK-GPS sensor are evaluated based on the quality of the received satellite signals, and the measurement from the RTK-GPS sensor is fused with the acceleration measured from the accelerometer using a two-stage Kalman filter. The performance of the proposed method is validated through a series of lab-scale tests and a field test conducted on Yeongjong Grand Bridge in South Korea. In the tests, the accuracy of the estimated vertical displacement was about 2 mm, and displacement, velocity, and acceleration are all simultaneously estimated at a sampling rate of 100 Hz.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new displacement estimation method is proposed for high accuracy and sampling rate. </LI> <LI> The proposed method enhances the accuracy and sampling rate up to 2 mm and 100 Hz. </LI> <LI> The proposed method estimates the displacement, velocity, and acceleration simultaneously. </LI> <LI> From a field test, the RMSE of displacement was 1.55 mm with the proposed method. </LI> </UL> </P>

Vision-based remote 6-DOF structural displacement monitoring system using a unique marker

Jeon, Haemin,Kim, Youngjae,Lee, Donghwa,Myung, Hyun Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.6

Structural displacement is an important indicator for assessing structural safety. For structural displacement monitoring, vision-based displacement measurement systems have been widely developed; however, most systems estimate only 1 or 2-DOF translational displacement. To monitor the 6-DOF structural displacement with high accuracy, a vision-based displacement measurement system with a uniquely designed marker is proposed in this paper. The system is composed of a uniquely designed marker and a camera with a zooming capability, and relative translational and rotational displacement between the marker and the camera is estimated by finding a homography transformation. The novel marker is designed to make the system robust to measurement noise based on a sensitivity analysis of the conventional marker and it has been verified through Monte Carlo simulation results. The performance of the displacement estimation has been verified through two kinds of experimental tests; using a shaking table and a motorized stage. The results show that the system estimates the structural 6-DOF displacement, especially the translational displacement in Z-axis, with high accuracy in real time and is robust to measurement noise.

국내실향민의 법적 보호와 국가책임

최득진(Choi Dok-Jin) 중앙대학교 법학연구원 2006 法學論文集 Vol.30 No.1

  (1) 1993년 3월 UN 인권위원회는 점차 증가하는 IDPs와 그들의 고통을 심각히 통감하면서 UN 사무총장에게 IDPs의 인권문제를 정면으로 제기하여 그에 대한 대표임명을 요구하였다. 이에 따라 1993년 7월 UN 인권위원회는 IDPs 담당 사무총장대표로 수단(Sudan)의 Francis M. Deng 대사를 IDPs 담당사무총장대표(Representative of the secretary-General on Internally Displaced Persons)으로 임명하고 국내실향민보호제도의 정착을 위해 노력하고 있다. <BR>  (2) IDPs(InternaIly Displaced Persons)란 “특히 (in particular) 무력충돌, 일반화된 폭력상태, 인권침해, 자연 또는 인위적 재해를 피하기 위해 거주 또는 상주지로부터 도피 혹은 강제이주되어 국제적으로 승인된 국경을 넘지 않은 개인 및 집단을 말한다.” 이 지침에서의 정의는 무력충돌, 일반폭력(성폭력 등 포함, 필자 주), 인권침해, 재해, 강제이주 등 객관적 사항에 의해 난민의 발생 원인을 포괄적으로 규정하고 있다. 다시 말해 IDPs은 무력충돌, 내란, 자연 또는 인위적 재해, 인종, 종교, 국적, 특정사회집단의 구성원 신분 또는 정치적 의견을 이유로, 흑은 강제이주로 박해받을 공포 때문에 안전한 피난장소를 찾아 자국내에서 난민화 상태에 있는 사람들이다. 이들은 기본적 인권은 물론 생존권마저 보장되어 있지 않은 상황이다. 이들은 난민과 달리 자국내에 존재하기 때문에 국제사회의 적극적 보호를 받기가 힘든 상태이며, 난민(Refugees)과 같은 신분이면서도 타국의 영역적 비호를 받을 수 없다. 따라서 “Internally Displaced Persons”는 난민 관련 국제조약에 비추어 ‘국내실향민’으로 무력충돌 등으로 피난 또는 도피할 여유 없이 무력에 의한 국내강제이주(internal displacement) 정책의 결과로 강제퇴거 또는 강제이주 된 사람을 포함하는 개념이라 할 수 있다. <BR>  (3) 1995년 12월 국내실향민 담당 사무총장대표는 “법적 규범의 편찬과 분석”이라는 제목의 보고서를 인권위원회에 제출하였다. 그리고 인권위원회는 1996년 4월에 국내실향민 담당 사무총장에게 국내실향민의 위의 보고서를 기초로 “적절 안”을 책정해야 한다는 결의(제1996/52호)를 하였다. 그리고 1998년에는 “법적 규범의 편찬과 분석”의 제2부를 제출하였다. 1998년에는 국내실향민에 관한 지침(The Guiding Principles on Internal Displacement)이 담당 사무총장에 의해 UN 인권위원회에 제출되었다. 이 지침은 UN 인권위원회에 의해 정식으로 채택된 것이 아니다. 동 인권위원회는 이것을 결의(제1998/50호)로 ‘유의한다(takes note)’것으로 정리해 두었다. 담당 사무총장대표인 Francis M. Deng 수단의 대사는 모든 영역국과 대화와 지역적 워크숍 개최를 통해서 지침의 보급에 노력하고 있고, UN 기관들로 구성된 기관간상설위원회(Inter-Agency Standing Committee)도 현장 수준에서의 보급에 합의하였다. UN 총회는 “UN 기관, 지역적 및 NGO가 그 직무에 있어 지침을 사용하는 것을 평가하고 유의하면서 지침을 보급과 이를 적용할 것을 장려한다”는 취지의 결의(제54/167호)를 채택하였다. Walter Kalin은 ASIL(American Society of International Law)에 지침의 상세한 내용을 소개하고 있다. 이에 대한 지침은 Hand Book으로도 만들어져 각국과 NGO 등에 UN은 보급하고 있다. 더불어 UN 인권위원회는 이에 지침에 대한 기준을 확대 보급하여 줄 것을 국제사회에 요청하고 있는 바이기도 하다.<BR>  (4) ‘난민’과 ‘국내실향민’은 정치ㆍ경제ㆍ사회ㆍ문화 등 모든 면에서 그 지위가 극히 곤경에 처해 있다는 점에서 공통된다. 그러나 이와 같은 경우라 하여도 국제법상 양자에 대한 보호개념에 있어서는 매우 다르다. 난민보호는 난민지위에 관한 협약 제1조 2항에서 규정하는 바와 같이 “인종, 종교, 국적, 특정사회집단의 구성원 신분 또는 정치적 의견을 이유 로 박해를 받을 우려가 있다는 충분한 근거가 있는 공포로 인하여, 자신의 국적국 밖에 있는 자로서, 국적국의 보호를 받을 수 없거나, 또는 그러한 공포로 인하여 국적국의 보호를 원하지 아니하는 자, 또는 그러한 사태의 결과로 인하여 종전의 상주국 밖에 있는 무국적자로서, 상주국에 돌아갈 수 없거나, 또 는 그러한 공포로 인하여 상주국으로 돌아가는 것을 원하지 아니하는 자”를 인도적 측면에서 국제협력에 의해 제3국이 임의적으로 보호하는 것이다. 이와 같이 난민과 IDPs는 보호의 개념뿐만 아니라 보호 가능성 측면에서도 크게 차이가 있다. IDPs에 관한 ‘지침’은 법적 보호가 국가 책임이라는 것을 명확히 했다는 점에 있어서는 획기적이다.<BR>  (5) 국제법은 국제사회의 합의를 기초로 하고 있는 바, 그 법적 안정성은 국가 상호간의 신뢰관계에 입각   Internal displacement, affecting some 25 million people worldwide, has become increasingly recognized as one of the most tragic phenomena of the contemporary world. Often the consequence of traumatic experiences with violent conflicts, gross violations of human rights and related causes in which discrimination features significantly, displacement nearly always generates conditions of severe hardship and suffering for the affected populations. It breaks up families, cuts social and cultural ties, terminates dependable employment relationships, disrupts educational opportunities, denies access to such vital necessities as food, shelter and medicine, and exposes innocent persons to such acts of violence as attacks on camps, disappearances and rape. Whether they cluster in camps, escape into the countryside to hide from potential sources of persecution and violence or submerge into the community of the equally poor and dispossessed, the internally displaced are among the most vulnerable populations, desperately in need of protection and assistance.<BR>  In 1993, at the request of the Commission on Human Rights, prior Representative of the Secretary-General on internally displaced persons Francis M. Deng prepared his first study(E/CN.4/1993/35 Annex) of international standards relevant to internally displaced persons(IDPs). In a more comprehensive two-volume study presented in 1996(E/CN.4/1996/52/Add.2) and 1998(E/CN.4/1998/53/Add.l), Representative Deng concluded that existing law provided broad protection for the rights of internally displaced persons, but that there were also certain gray areas and gaps in coverage.<BR>  With the encouragement of the Commission of Human Rights(E/CN.4/RES/1996/52, para. 9) and the General Assembly, Representative Deng proceeded to develop a document setting out the relevant law and addressing the gray areas and gaps, with the help of a team of international legal scholars chaired by Mr. Walter K?lin(now Representative of the Secretary-General on the human rights of internally displaced persons). The resulting Guiding Principles on Internal Displacement(E/CN.4/1998/53/Add.2) were presented to the Commission on Human Rights in 1998.<BR>  The Commission has expressed its appreciation of the Guiding Principles as an important tool for dealing with internal displacement, and has welcomed the fact that an increasing number of States, United Nations agencies and regional and non-governmental organizations are applying them as a standard(E/CN.4/RES/2004/55, operative paragraph 6).<BR>  The Guiding Principles will enable the Representative to monitor more effectively situations of displacement and to dialogue with Governments and all pertinent actors on behalf of the internally displaced; to invite States to apply the Principles in providing protection, assistance, reintegration and development support for them; and to mobilize response by international agencies, regional intergovernmental and non-governmental organizations on the basis of the Principles. The Guiding Principles are therefore intended to be a persuasive statement that should provide not only practical guidance, but also an instrument for public policy education and consciousness-raising. By the same token, they have the potential to perform a preventive function in the urgently needed response to the global crisis of internal displacement.<BR>  Despite not being the beneficiaries of a specific convention, as is the case for refugees, internally displaced persons(IDPs) are protected by various bodies of law, principally national law, human rights law and, if they are in a State experiencing an armed conflict, international humanitarian law.<BR>  The majority of IDPs are nationals of the State in which they find themselves. As such, they are entitled to the full protection of national law and the rights it grants nationals, without any adverse distinction resul