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은충기 ( Eun Chung-ki ),이용재 ( Lee Yong-jae ),채원규 ( Chai Won-kyu ),손영현 ( Son Young-hyun ),신준관 ( Shin Jun-kwan ),정평기 ( Jung Pyung-ki ) 한국구조물진단유지관리공학회 1998 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.2 No.2
To evaluate the relationship between the destructive and non-destructive measuring methods, an experimental study for the compressive strength of concrete had been performed and the test results have been analysied. The rebound hammer test and the ultrasonic pulse velocity test was carried out as the non-destructive measuring methods. In this study, for the range of design strengths between 40MPa and 80MPa, the compressive strength test was carried out using the cubic specimen. The age to check the strength was 28 days. On the basis of the correlationship analysis for the test result, some experimental equation for the compressive strength were proposed.
시스템 확인 기법을 이용한 기존 구조물의 손상도 추정에 관한 연구
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2005 한국고등직업교육학회논문집 Vol.6 No.4
Structures require complicated element models with a number of degrees of freedom in structural analysis. During experiment much effort and cost is needed for measuring structural parameters. The sparseness and errors of measured data have to be considered during the parameter estimation of structures. In this paper we introduces damage identification algorithm by a system identification(S.I) using static and dynamic response. To study the behaviour of the estimators in noisy environment using Monte Carlo simulation, and a data measured perturbation scheme is adopted to investigate the influence of measurement errors on identification results. The assessment result by static and dynamic response were compared, and the efficiency and applicabilities of the proposed algorithm are demonstrated through simulated static and dynamic responses of a two dimensional truss type structures.
강섬유보강 고강도콘크리트의 응력-변형율 곡선 모델 제안
손영현 ( Son Young-nyun ),은충기 ( Eun Chung-ki ),채원규 ( Chai Won-kyu ),김광일 ( Kim Kwang-il ) 한국구조물진단유지관리공학회 2001 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.5 No.1
In this study, the compression test of steel fiber reinforced high-strength concrete have been conducted with varying strengths and volume fractions of steel fiber. Three types of matrices including low strength concrete( f<sub>c</sub>’ = 50 MPa), medium strength concrete( f<sub>c</sub> ‘=50 MPa), and high strength concrete( J<sub>c</sub>’ =70 MPa) were selected. Five types of steel fiber fractions were studied including 0.0%, 0.5%, 0.75%, 1.0%, and 1.5% by volume. From the results of the test, the stress-strain relationship which explicitly considers the design strengths, the volume fractions and the aspect ratio of the steel fiber was experimentally proposed. This proposed equation was found to be agreed well with the present test results.
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2008 한국고등직업교육학회논문집 Vol.9 No.4
They are essential elements in performance and safety of structures during the service life. The damage of structures might cause the critical risk to the safety. Therefore, it is very important to detect the damage. For this purpose, using System Identification method, one of the nondestructive tests, we can verify models and assess the damage of structures. In this paper, it is proposed that the parameter estimation algorithm takes account of the static displacements of the structure and the modal data such that eigenvalues and eigen modes of given model, and compared with the results from the static data including the static displacements of the structure and the stiffness of the model to investigate the effectiveness of the algorithm. It is compared with two shapes of the parameter estimation error and the extent of the total error using static and modal data for the different load cases. Consequently, parameter estimation using modal data is less affected by the sets of loads and cause small estimation error as compared with that using static data.
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2007 한국고등직업교육학회논문집 Vol.8 No.4
Load bearing structural members in a wide variety of applications accumulate damage over their service life. From a standpoint of both safety and performance, it is desirable to monitor the occurrence, location, and extent of such damage. The sparseness and errors of measured data have to be considered during the parameter estimation of structures. In this paper we introduces parameter identification algorithm by a system identification (S.I.) using static and dynamic response. To study the behaviour of the estimators in noisy environment using Monte Carlo simulation, a data measured perturbation scheme is adopted to investigate the influence of measurement errors on identification results. To examine the influence of the measured data, noisy and number of load case(measured mode), measured Dofs, initial values are used The assessment result by dynamic and static response were compared, and the efficiency and applicabilities of the proposed algorithm are demonstrated through simulated dynamic and static responses of a two dimensional truss type structures.
동특성 데이터를 이용한 교량의 손상진단에 대한 수치모의실험
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2011 한국고등직업교육학회논문집 Vol.12 No.1
This paper is estimated the damage of truss bridge based on System Identification(S.I.) using modal test data. Generally, civil structures mainly require sophisticated finite element models having a number of degrees of freedom, also in experiments and measurements on structures. The sparseness and errors of measured data have to be considered during the damage assessment of structures. To study the behaviour of the estimators in noisy environment using Monte Carlo simulation, and a data measured perturbation scheme is adopted to investigate the influence of measurement errors on identification results. The assessment result by equation error function and response error function were compared, and the efficiency and applicabilities of the proposed algorithm are demonstrated through simulated modal test data of a truss bridge.
손영현 ( Son Young-hyun ),은충기 ( Eun Chung-ki ),채원규 ( Chai Won-kyu ),김광일 ( Kim Kwang-il ) 한국구조물진단유지관리공학회 2001 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.5 No.1
In this study, the flexural test for steel fiber reinforced concrete beams have been conducted. Three types of matrices including low-strength concrete, medium- strength concrete, and high-strength concrete were selected. Five types of steel fiber fractions were studied. Four types of initial notch-to-depth ratios were used. On the basis of the test results, the fracture energy is considerably influenced by the parameters, that is, the design strength, the liber volume fraction, and the initial notch-depth ratio. The notch sensitivity is softened by the mixing of the steel fiber when the strength is higher and higher. And, the proposed parameter for the sensitivity can describe the fracture characteristics of steel fiber reinforced concrete.
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2006 한국고등직업교육학회논문집 Vol.7 No.4
Skew bridges are found frequently in new bridge construction due to geographical conditions when new construction bridges are put across the existing highways, railroads or rivers. This research investigated effect that slab and support reaction in case seismic load interacts to moment resisting rahmen bridge that have skew angles. Could know that goods to aid in a funeral negative torsional moment and reaction force of span central part increase study finding angle of field is decrescent, and can know that reaction force increases rapidly if pass over angles 60° specially. If examine skews and span central part by time and support parts stress change, angles comers decreases, stress of span central part shows big increase fairly and span support parts stress could know that look tendency that decrease passing over angles 60° while increase.
확장형 칼만필터링을 이용한 구조물의 손상 진단 기법에 관한 연구
박우진 ( Woo-jin Park ),은충기 ( Chung-ki Eun ) 한국고등직업교육학회 2009 한국고등직업교육학회논문집 Vol.10 No.4
Structures require complicated element models with a number of degrees of freedom in structural analysis. During experiment much effort and cost is needed for measuring structural parameters. The sparseness and error of measured data have to be considered during the parameter estimation of structures. This paper is estimated the damage of truss structure based on extended Kalman filtering method. The measurement data is adopted natural frequency of damaged truss structure. In the truss structure, measurement and position of damages can be estimated by inverse solution procedure with the extended Kalman filtering method. The verification of the applicability and effectiveness for the proposed method are established to plane truss structure model and accomplished to damage detection analysis by simulation.