활성단층 조사에 활용되는 원격탐사 기술과 사례의 고찰

권오상 ( Ohsang Gwon ),손효록 ( Hyorok Son ),배상열 ( Sangyeol Bae ),박기웅 ( Kiwoong Park ),최호석 ( Ho-seok Choi ),김영석 ( Young-seog Kim ),이승국 ( Seoung-kuk Lee ) 대한원격탐사학회 2021 大韓遠隔探査學會誌 Vol.37 No.6

대부분의 대규모 지진은 기존의 활성단층이 재활하여 발생하므로, 이러한 활성단층의 위치와 특성을 파악하는 것은 지진재해 연구와 지진방재 측면에서 매우 중요하다. 최근에는 활성단층 조사에서 지표지질조사에 앞서 실시하는 선형구조 분석에 다양한 원격탐사 기술이 유용하게 활용되고 있다. 본 논문에서는 원격탐사 기술 중 이러한 활성단층 조사에 널리 활용되는 위성원격탐사, 항공원격탐사, 그리고 InSAR, LiDAR 기법의 간단한 원리와 적용사례를 소개하고자 한다. 또한, GIS를 활용하여 단층활동에 의해 형성된 경사급변점과 주향이동단층의 수평변위를 분석한 사례를 소개하고자 한다. 토의에서는 항공사진을 활용하여 DEM을 구축할 때 발생할 수 있는 문제점들과 해결방안, 항공 LiDAR 기반 DEM의 문제점을 극복하여 개발한 새로운 기법인 RRIM에 대해 논의하고자 한다. 활성단층 조사에서 어떤 원격탐사 기술이 활용되는지 이해하고 각 원격탐사 기법의 장단점과 한계점을 이해하여 상황에 따라 적절한 방법을 활용하는 것은 효율적인 활성단층조사를 위해 중요하다. Since most large earthquakes occur by reactivation of preexisting active faults, it is important to understand the locations and characteristics of active faults in terms of earthquake hazard research and earthquake disaster prevention. Recently, several remote sensing techniques are broadly used for lineament analysis performed prior to field surveys in active fault surveys. The aim of this paper is introducing simple principles and application examples of each remote sensing technique (satellite remote sensing, airborne remote sensing, InSAR, LiDAR) widely used for active fault investigation. This paper also explains the analytical methods for the slope break generated by fault activity based on GIS and the horizontal displacement of the strike-slip fault. In discussion, we would like to discuss the problems and solutions on making DEM based on aerial photography, and a new developed technique (RRIM) to overcome the problems of DEM based on aerial LiDAR. Understanding remote sensing techniques used for active fault investigation and utilizing appropriate methods depending on the situation and limitations of each remote sensing technique are important for effective active fault investigation.

지형 분석을 통한 활성 단층 추적 연구

신재열,홍영민,김형수,이광률 한국지형학회 2019 한국지형학회지 Vol.26 No.4

This study documents the distribution of (active) faults around the southern part of the Yangsan Fault and the Moryang Fault and the middle part of the Dongrae Fault. For this objective, we extracted lineaments and fault-related landforms by analyzing aerial photos and digital elevation models and with the result of fieldwork on fault-relating features of the Quaternary landforms. Geomorphological techniques for active fault study are not only preliminary but also essential methods because, in general, an active fault can be defined only with fault-deformed Quaternary sediments when there is no way to detect precise timing of faulting. Therefore, geomorphological interpretation in active fault research is necessary to determine the extent, direction, termination and timing of fault. This study addresses the results of such geomorphological analysis and geomorphic markers for tracing the active faults in the study area. It is plan to investigate with geophysical and geological techniques the sites referred in this study.

Seismicity, active faults, stress patterns, and rupture processes in the Hualien region, Taiwan, investigated using the 1990 Hualien earthquake sequence

Lee, Chien-Ping,Kim, Kwang-Hee,Huang, Bor-Shouh,Huang, Win-Gee Elsevier 2011 Tectonophysics Vol.511 No.1

<P><B>Abstract</B></P><P>The Hualien mainshock–aftershock sequence from December 1990 to January 1991 was used to investigate seismicity, active faults, stress patterns, and complex rupture processes in the Hualien region of eastern Taiwan. A combined data set, compiled from observations by the regional seismic network (Taiwan Telemetered Seismograph Network, TTSN) and a dense aftershock monitoring array (Hualien Temporary Seismic Network, HTSN), provided high-quality seismic data. Using these data, earthquake source parameters could be well constrained by the joint hypocenter determination (JHD) and double-difference relocation methods. These two relocation methods presented similar results and produced improved estimations of earthquake location. Station corrections determined by JHD showed significant lateral velocity variations across the Yuehmei fault. The relocated seismicity indicated that a previously known active fault, the Chimei fault, extends to offshore. Earthquake relocations also revealed a northwest dipping seismicity probably related to the Chimei fault. In addition, three sets of focal mechanism solutions are presented and their discrepancies are attributed to the complex rupture process. At first, earthquakes were initiated by thrust motions. Later, the rupture pattern changed to strike–slip motions. Variations in slip may reflect the fault geometry or rupture boundary conditions in the region. The observed stress patterns are considered to relate not only to the regional collision and mountain-building processes, but also to active faults in local structures.</P> <P><B>Highlights</B></P><P>► Active faults along the collision boundary are analyzed using 1990 Hualien earthquake sequence. ► Precise earthquake locations indicate previously known active faults and blind faults. ► Differences in three sets of focal mechanism solutions indicate complex rupture processes of earthquake initiation and evolution in the eastern Taiwan. ► Observed stress patterns from focal mechanism solutions also indicate the role of regional tectonics and local faults.</P>

울산단층대 주변의 단층 지형 및 선구조 분포

이광률 ( Lee Gwang-ryul ),박충선 ( Park Chung-sun ),신재열 ( Shin Jae-ryul ) 한국지형학회 2018 한국지형학회지 Vol.25 No.3

This study presents results of analysis on fault-related landforms and the Quaternary fluvial landforms, which are important evidences for active faulting by identifying surface deformation, around the Ulsan Fault Zone. In addition, this study suggests lineament map and inferred active fault-line map based on analyzing linearity and continuity of these landforms and by compiling location information of existing active faults. We convince that quantitative tectonic-geomorphological analysis are an effective method for active faults tracking, in particular, considering the conditions of relatively low seismicity and surface ruptured-events in the Korean Peninsula compared to plate boundary active areas. However, research on active fault in South Korea is just an infant stage since the 1990s and requires accumulation of research achievements on development and application of various fault analysis techniques, analysing and standardizing linear structures.

DEGREE OF FAULT ISOLABILITY AND ACTIVE FAULT DIAGNOSIS FOR REDUNDANTLY ACTUATED VEHICLE SYSTEM

S. PARK,Y. PARK,Y. S. PARK 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.6

This paper proposes á degree of fault isolability concept and active fault diagnosis method for redundantly actuated vehicle systems. Fault isolability is a structural property related to system dynamics and composition of actuators and sensors. Existing research on testing fault isolability has involved checking whether the system is isolable, i.e., binary in nature. A continuous value rather than a binary metric is needed to evaluate how isolable a given system fault is based on a specific measurement set. After fault components are isolated, the fault type and magnitude are estimated by analyzing residual vectors. In a redundantly actuated system, the number of controls/actuators is greater than the system mobility. Thus, the control input distribution to achieve a given control objective is not unique. In the case of a fault, the active fault diagnosis system adjusts the control input distribution to diagnose the fault. Thus, much more system information can be identified by additional excitation through a redundantly actuated system, which improves the fault diagnosis performance. Simulation results of a four-wheel independently driven and steered vehicle model validated the proposed degree of fault isolability and the effectiveness of the proposed active fault diagnosis method.

LiDAR 기법의 기본원리와 지질학적 적용

김현태 ( Hyun Tae Kim ),김영석 ( Young Seog Kim ),위광재 ( Kwang Jae We ) 대한지질공학회 2014 지질공학 Vol.24 No.1

지진은 인적, 물적으로 많은 피해를 야기시키기 때문에 지진피해를 저감하기 위해서 활성단층에 대한 연구가 최근 매우 다양한 방법으로 진행되고 있다. 이러한 연구를 위해서는 활성단층의 존재를 밝히는 것이 우선되어야 하는데 기존 연구에서는 주로 항공사진, 위성사진 그리고 낮은 해상도의 DEM 등을 이용하여 선형구조를 분석하여 주로 연구를 수행하였다. 하지만 단층의 활성도가 상대적으로 낮은 한국의 지체구조 및 지형특성과 수목이 많은 단점으로 인해 기존의 연구방법은 많은 한계를 가지고 있었다. 이번 논문에서는 이러한 한계를 극복하기 위해 최근 세계적으로 많은 주목을 받고 있는 원격탐사 방법인 LiDAR 기법에 대해 소개하고 자료 사용법에 대해 간략히 소개하고자 한다. 특히 이 논문에서는 아직 국내에서는 보편화되지 않은 항공 LiDAR 기법을 이용한 연구방법에 대한 최근의 이해를 간략히 소개하고, 국내외의 자료를 통해 지질학에 어떻게 이 기법을 적용할 수 있을지에 대해 소개하고 더 나은 방안을 모색해 보고자 하였다. Earthquakes can cause serious loss of life and significant property damage. Thus, the study of active faults is important in evaluating future fault activity and hazards caused by future earthquake events. Structural mapping and the tracing of active faults are the primary steps in studies of active faults. Until now, active faults in South Korea have been mapped using aerial photography, satellite images, and low-quality DEMs. Lineament analysis as a means of identifying active faults is relatively difficult in Korea due to geological characteristics (weak tectonic activity) and dense vegetation cover. In this paper, we introduce the basic concept of the LiDAR technique (a new prospective remote sensing method) and a data analysis method that can overcome these problems. This paper will contribute to a better understanding of the airborne LiDAR technique and its application to South Korea. Some preliminary results from Korean and USA LiDAR data show the usefulness of this technique for tracing lineaments, active faults, and terraces in South Korea.

Fault Diagnosis for a Class of Active Suspension Systems with Dynamic Actuators’ Faults

Gang Tao,Zehui Mao,Yue Wang,Bin Jiang 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.5

In this paper, a new fault diagnosis and fault-tolerant control method for a class of active suspensionsystems with actuator faults is proposed. The considered actuators have uncertain dynamic characteristics, whichare the electromagnetic actuators made up with a motor control system and a ball screw transmission mechanism. To detect such suspension system actuator faults, dynamic fault diagnosis observers are designed for the actuatorsto estimate the possible faults. The actuators are analyzed to first and second order dynamic models, respectively,whose output can be measured but the rate is non-measurable. Then, the fault diagnosis method is developedfor these two kinds of models to obtain the fault information. Using the fault estimation and adaptive controltechnique, a robust fault-tolerant controller is constructed to guarantee the performance of the rail vehicles in thefaulty case. Finally, using the parameters of a practical suspension system, a simulation study is conducted to showthe effectiveness of the proposed method.

Semi-active structural fuzzy control with MR dampers subjected to near-fault ground motions having forward directivity and fling step

Hosein Ghaffarzadeh 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.6

Semi-active control equipments are used to effectually enhance the seismic behavior of structures. Magneto-rheological (MR) dampers are semi-active devices that can be utilized to control the response of structures during seismic loads and have received voracious attention for response suppression. They supply the adaptability of active devices and stability and reliability of passive devices. This paper presents an optimal fuzzy logic control scheme for vibration mitigation of buildings using magneto-rheological dampers subjected to near-fault ground motions. Near-fault features including a directivity pulse in the fault-normal direction and a fling step in the fault-parallel direction are considered in the requisite ground motion records. The membership functions and fuzzy rules of fuzzy controller were optimized by genetic algorithm (GA). Numerical study is performed to analyze the influences of near-fault ground motions on a building that is equipped with MR dampers. Considering the uncontrolled system response as the base line, the proposed method is scrutinized by analogy with that of a conventional maximum dissipation energy (MED) controller to accentuate the effectiveness of the fuzzy logic algorithm. Results reveal that the fuzzy logic controllers can efficiently improve the structural responses and MR dampers are quite promising for reducing seismic responses during near-fault earthquakes.

IGBT Open-Circuit Fault Diagnosis for 3-Phase 4-Wire 3-Level Active Power Filters based on Voltage Error Correlation

Ke Wang,Yi Tang,Xiao Zhang,Yang Wang,Chuan-Jin Zhang,Hui Zhang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

A novel open-circuit fault diagnosis method for 3-phase 4-wire 3-level active power filters based on voltage error correlation is proposed in this paper. This method is based on observing the output pole voltage error of the active power filter through two kinds of algorithms. One algorithm is a voltage error analytical algorithm, which derives four output voltage error analytic expressions through the pulse state, current value and dc bus voltage, respectively, assuming that all of the IGBTs of a certain phase come to an OC fault. The other algorithm is a current circuit equation algorithm, which calculates the real-time output voltage error through basic circuit theory. A correlation is introduced to measure the similarity of the output voltage errors between the two algorithms, and OC faults are located by the maximum of the correlations. A FPGA has been chosen to implement the proposed method due to its fast prototyping. Simulation and experimental results are presented to show the performance of the proposed OC fault diagnosis method.

Active Fault-Tolerant Control for a Class of Nonlinear Systems with Sensor Faults

Youqing Wang,Donghua Zhou,S. Joe Qin,Hong Wang 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.3

A general active fault-tolerant control framework is proposed for nonlinear systems with sensor faults. According to their identifiability, all sensor faults are divided into two classes: identifiable faults and non-identifiable faults. In the healthy case, the control objective is such that all outputs converge to their given set-points. A fault detection and isolation module is firstly built, which can produce an alarm when there is a fault in the system and also tell us which sensor has a fault. If the fault is identifiable, the control objective remains the same as in the healthy case; while if the fault is non-identifiable, the control objective degenerates to be such that only the healthy outputs converge to the set-points. A numerical example is given to illustrate the effectiveness and feasibility of the proposed method and encouraging results have been obtained.