이종 계측기기의 신호처리 지원 시스템 구축을 위한 사용자 인터페이스 개발

허광희 ( Heo¸ Gwanghee ),손동진 ( Sohn¸ Dongjin ),정기수 ( Jung¸ Kisoo ) 한국구조물진단유지관리공학회 2009 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.13 No.1

The purpose of the paper is to design a system that is to support signal processing of each different type of transmitter and also develop a user interface where the designed system can be utilized for the measurement and maintenance of structures. Normally a measuring device logs only the same data because of its features that are characteristic of itself. However, in order to evaluate the health of real-time monitoring systems, it is needed to acquire various kinds of data by using different types of measuring devices. This paper is therefore concerned with the development of a system where users would be able to properly process the signals acquired from various kinds of measuring devices. In other words, the signal processing system that is developed here will be able to simultaneously acquire different data such as a broad range of acceleration or strain gauge. And also this developed system is proven to be valid.

육교 구조물의 붕괴사고

허광희 ( Heo¸ Gwanghee ),이진옥 ( Lee¸ Chin Ok ),김유식 ( Kim¸ Yusik ) 한국구조물진단유지관리공학회 2004 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.8 No.2

2D-Dynamic Strain Energy를 이용한 모형사장교의 손상평가

허광희 ( Heo¸ Gwanghee ),이규 ( Lee Giu ),최만용 ( Choi¸ Mhan-young ),신형철 ( Shin Heung Chul ),이진옥 ( Chin Ok Lee ) 한국구조물진단유지관리공학회 2002 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.6 No.2

This paper aims to develop a method to designate damage points and assess their degrees in cable-stayed bridges by calculating the dynamic strain energy change on two-dimensional level. First of all, we present a method by which the damage index is obtained, and then we calculate a damage index using numerically obtained modal data according to the presented method. Next, all those data are classified into two categories: data before damage and ones after damage. And then the normalized damage index is calculated. In order to get modal data, we make up four damage scenarios: cable damage, single deck damage, one-direction double damage, and two-direction double damage. Each of Modal data from those damage scenarios were used to the tenth mode, and the degree of damage was made to be between three and nine percents in load capacity ratio. Although damage point is rather ambiguous in the double damage scenario, all in all, the damage points and its degree were relatively well designated in all damage scenarios.

지진하중을 받는 사장교의 상태평가를 위한 새로운 통계적 패턴 인식 기술

허광희,김충길,Heo, Gwanghee,Kim, Chunggil 대한토목학회 2014 대한토목학회논문집 Vol.34 No.3

마할라노비스 거리 이론에 기초한 통계적 패턴 인식 기술은 안정된 외부하중에 대한 구조물 상태 평가에 대한 유용성에도 불구하고 지진과 같이 큰 변동성의 외부하중에 대한 구조물의 건전도 모니터링에는 취약하다. 손상은 일반적으로 손상되지 않은 구조물의 측정된 값의 평균과 손상된 구조물의 측정값 사이의 차이에 의해 결정된다. 외부 하중의 변동성이 커질수록 더 큰 차이가 발생하고, 이는 손상으로 인식되기 쉽다. 본 논문에서는 이러한 문제를 극복하고 불확실한 외부 하중을 받는 구조물을 지속적으로 모니터링 할 수 있도록 외부 변동성을 감소시키기 위해 마할라노비스 거리 이론을 수정한 통계적 패턴 인식 기술인 개선된 마할라노비스 거리 이론을 개발하였다. 이 방법은 일반적인 임의의 하중과 지진하중에서 정확하게 사장교의 건전도를 평가하는 것을 실험적으로 확인 하였다. 그 결과, IMDT는 손상되지 않은 케이블로부터 획득한 데이터로 손상된 케이블에 의한 구조물의 손상을 파악하는 데 유효한 것을 확인하였다. 따라서 변동성을 지닌 외부하중에 의한 교량의 건전도 모니터링에 효과적으로 적용할 수 있음을 입증하였다. In spite of its usefulness for health monitoring of structures on steady external load, the statistical pattern recognition technology (SPRT), based on Mahalanobis distance theory (MDT), is not good enough for the health monitoring of structures on large variability external load like earthquake. Damage is usually determined by the difference between the average measured value of undamaged structure and the measure value of damaged one. So when external variability gets larger, the difference gets bigger along, which is thus easily mistaken for a damage. This paper aims to overcome the problem and develop an improved Mahalanobis distance theory (IMDT), that is, a SPRT with revised MDT in order to decrease external variability so that we will be able to continue to monitor the structure on uncertain external variability. This method is experimentally tested to see if it precisely evaluates the health of a cable-stayed bridge on each general random load and earthquake load. As a result, the IMDT is found to be valid in locating structural damage made by damaged cables by means of data from undamaged cables. So it is proved to be effectively applicable to the health monitoring of bridges on external load of variability.

전단형 MR 댐퍼를 이용한 케이블 교량의 실시간 진동제어-파워 모델 및 리야프노브 제어 중심으로

허광희,이진옥,전승곤,김충길,전준용,Heo, Gwanghee,Lee, Chinok,Jeon, Seunggon,Kim, Chunggil,Jeon, Joonryong 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.5

In this paper, an experimental study was carried out for vibration control of cable bridges with structurally flexible characteristics. For the experiment on vibration control, a model bridge was constructed by reducing the Seohae Grand Bridge and the shear type MR damper was designed using the wind load response measured at Seohae Grand Bridge. The shear type MR damper was installed in the vertical direction at the middle span of the model bridge, and dynamic modeling was performed using the power model. The tests of the vibration control were carried out by non-control, passive on/off control and Lyapunov control method on model bridge with scaled wind load response. The performance of the vibration control was evaluated by calculating absolute maximum displacement, RMS displacement, absolute maximum acceleration, RMS acceleration, and size of applied power using the response (displacement, acceleration, etc.) from the model bridge. As a result, the power model was effective in simulating the nonlinear behavior of the MR damper, and the Lyapunov control method using the MR damper was able to control the vibration of the structure and reduce the size of the power supply.

비대칭사장교의 동특성 분석을 위한 FE 모델링

허광희,전승곤,김충길,안의종 한국구조물진단유지관리학회 2011 한국구조물진단학회 학술발표회논문집 Vol.2011 No.9

Asymmetrical Cable-stayed bridges are often built asymmetrically due to their circumstances around them. Such asymmetrical bridges keep their structural equilibrium generally by transmitting their load from the central longer span into their main tower and the other side foundation piles. This unusual asymmetrical structure has unique dynamic characteristics when it vibrates due to random load. The asymmetrical bridge concerned here is composed of a main tower and a upper deck of steel composite structure, in which the cables are tied along the center line of the longer span, and again connected to the other side of foundation piles through the main tower. For the exact analysis of its dynamic characteristics, which is essential to the monitoring for bridge maintenance, this paper developed its three-dimensional FE modelling which turn out to be appropriate FE analyses by solving the problems involved in transforming the different size of sections and their center of the mass. For evaluation, we first measured structural vibration using ambient vibration, then obtained cross correlation function by the FFT of cross power spectrum, and finally analyzed the dynamic characteristics of the bridge structure. As results, the FE modelling suggested here was proven effective.

Lyapunov 알고리즘을 이용한 교량구조물의 무선 진동제어

허광희,김충길,전승곤,안의종,이진옥 한국구조물진단유지관리학회 2011 한국구조물진단학회 학술발표회논문집 Vol.2011 No.9

In order to keep in control the long and large bridges whose vibration by external loads is fatal to their own structure, the adoption of wired system for vibration control entails some problems such as high initial set-up cost and onerous maintenance. This paper attempts to solve the problems by developing a TCP/IP based wireless vibration-control system which fits better outdoors and also by applying Lyapunov algorithm which has been proven to work well for semi-active control system. The performance of the Lyapunov -algorithm-applied wireless vibration-control system was evaluated through experiments with a model structure and a semi-active control device both of which were designed for this particular research. The experiments proved the wireless vibration-control system developed here was effective.

MR 댐퍼를 이용한 비대칭 사장교의 지진 진동제어 성능평가

허광희,김충길,공영이,Heo, Gwanghee,Kim, Chunggil,Gong, Yeong I 대한토목학회 2014 대한토목학회논문집 Vol.34 No.3

비대칭 사장교에 지진으로 인한 진동을 MR(Magneto-rheological) 댐퍼를 이용하여 효과적으로 제어하는 연구를 수행하였다. MR 댐퍼의 실용적인 사용성을 높이기 위하여 비대칭 사장교 구조물을 설계/제작하고, 이 교량구조물을 적정하게 제어할 수 있도록 MR 댐퍼를 제작하였다. El-centro 지진파로 비대칭 사장교를 수평방향으로 가진하여 수직방향과 수평방향의 진동을 제어하는 실험을 하였다. 각 방향의 진동제어 실험에 5가지의 제어 조건으로 MR 댐퍼의 제어성능을 평가 하였다. 실험결과 MR 댐퍼는 지진진동으로 인한 비대징사장교를 진동제어 하기 위하여 Lyapunov Control 알고리즘과 Clipped-optimal control 알고리즘을 이용하여 제어를 할 경우, 보다 효과적으로 진동을 제어하는 것을 알 수 있었다. 그리고 구조물의 비대칭성과 수평 가진으로 인하여 수직 및 수평 방향의 진동제어가 서로 다른 제어효과를 보였다. 이와 같은 제어효과는 비대칭 사장교와 같은 유연하며 비대칭인 구조물에 준능동의 MR 댐퍼가 효과적으로 지진진동을 제어하는 것으로 평가되었다. A study has been carried out that effectively controls the vibration of asymmetric cable-stayed bridges caused by earthquakes with MR dampers. In order to enhance the practical serviceability of MR dampers, an asymmetric cable-stayed bridge structure has been designed and produced, and a MR damper has been produced so as to have this bridge structure controlled appropriately. An experiment that controls vertical and horizontal vibrations has been carried out by exciting the asymmetric cable-stayed bridge in the horizontal direction with the El-centro seismic wave. The control performance of the MR damper has been evaluated under the five control conditions in the experiments of vibration control in each direction. As a result of the experiment, MR dampers were proved to control vibrations more effectively when either Lyapunov control algorithm or Clipped-optimal control algorithm was used to control vibrations of the asymmetric cable-stayed bridge caused by earthquakes. In addition, different controlling effects were found in vibration controls in vertical and horizontal directions due to the asymmetry of the structure and the horizontal excitation. With such controlling effects, semi-active MR dampers are evaluated to effectively control vibrations caused by earthquakes in flexible and asymmetric structures such as asymmetric cable-stayed bridges.

모달 Updating을 통한 소형 모형 사장교의 Structural Integrity 개발

허광희(Heo, Gwanghee),오주원(Oh, Juwon),정기수(Jung, Kisoo),정의태(Jung, Euitae) 한국구조물진단유지관리학회 2009 한국구조물진단학회 학술발표회논문집 Vol.2009 No.1

The dynamic characteristics of bridge structures acquired by modelling are determined by their rigidity and mass calculated on their geometrical dimension. In the case of a small model bridge, a tiny bit of change in its rigidity and mass makes a big difference in its structural features. Normally a cable-stayed bridge is designed to have the load of the mid-part of its main span supported by the rigidity of cables, which thus absolutely determines its dynamic characteristics. So, an exact FE modelling is required, but there are some errors due to the limit of numerical analysis, which accordingly necessitates an experimental modal updating as a complement. This particular research aims to improve the structural integrity by the modal updating as a result of comparing two sets of different dynamic characteristics, one from a FE analysis, the other from an experiment. That improvement was evaluated by the MAC value which resulted from the analysis of the relationship between error possibilities in proper vibration and their modes both before and after modal updating. The evaluation proved that the modal updating was valid as a way to improve the structural integrity of a small model cable-stayed bridge..

유압-로프식 수문 개폐를 위한 FDC 시스템 개발 : Part 2 : FDC 시스템의 구현 및 성능 평가

허광희(Heo Gwanghee),김충길(Kim Chunggil) 대한토목학회 2009 대한토목학회 학술대회 Vol.2009 No.10