지진학적 모델에 근거한 고주파 지반 운동의 통계적 시뮬레이션 : 재고 및 국내 연구과제

노명현,이기화 대한지질학회 1992 대한지질학회 학술대회 Vol.1992 No.

다양한 임베디드 층간분리를 갖는 복합 적층판의 자유 진동 해석

노명현,박대용,이상열 한국복합신소재구조학회 2012 복합신소재구조학회 학술발표회 Vol.2012 No.04

This paper presents free vibration characteristics of laminated composite plates with different embedded delamination sizes and locations using three-dimensional finite elements. The free vibration analysis using the 3D finite element (FE) delamination model has merits in that it shows better accuracy but also shows the entire mode shape compared to the conventional approaches. This study investigates free vibration characteristics of laminated composite plates containing an various embedded delamination. The numerical results obtained are in good agreement with those reported by other investigators. Specifically, in this paper, attention is paid to the effects of the local vibration mode for various parameters, such as size of delamination, aspect ratio, and location of delamination.

GFRP 보강 직사각형 RC벽체의 충돌거동 수치해석

노명현,이상열 한국복합신소재구조학회 2011 복합신소재구조학회 학술발표회 Vol.2011 No.04

This study investigates impact damage behavior of a reinforced concrete structure that undergoes both a shock impulsive loading and an impact loading due to the air blast induced from an explosion is performed. Firstly, a pair of multiple loadings are selected from the scenario that an imaginary explosion accident is assumed. The rectangular RC walls strengthened with Glass Fiber Reinforced Polymer (GFRP) are considered as a scheme for retrofitting rectangular RC wall structures subjected to multiple explosive loadings and then the evaluation of the resistant performance against them is presented in comparison with the result of the evaluation of a rectangular RC wall without retrofit. Also, in order to derive the result of the analysis similar to that of real explosion experiments, which require the vast investment and expense for facilities, the constitutive equation and the equation of state (EOS) which can describe the real impact and shock phenomena accurately are included with them. In addition, the numerical simulations of two rectangular RC walls are achieved using AUTODYN-3D, an explicit analysis program, in order to prove the retrofit performance of a GFRP-strengthened rectangular RC wall.

Tensile force identification in cable-stayed structures: Hybrid system identification algorithm and experimental verification

노명현,허종완 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.11

In this study, we investigate a method to detect tensile forces in cable-stayed structures using the combined sensitivity updating methodand the advanced hybrid microgenetic algorithm. The proposed method allows us not only to avoid the trap of minimum at initial searchingstage but also to find their final solutions in better numerical efficiency. The validity of the technique is numerically verified using aset of dynamic data obtained from a simulation of the cable model modeled using the finite element method. Then, the hybrid algorithmis applied to vibrating sagged cables in the laboratory scale test. The results obtained are in good agreement with the semi-analytical solutionsand experimental results reported by other investigators. The results indicate that the new method is computationally efficient incharacterizing the tensile force variation for cable-stayed structures.

Experimental Investigation of Dynamic Behavior of Prestressed Girders with Internal Tendons

노명현,성택룡,이정휘,박규식 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.2

In this study, the dynamic behavior of internally prestressed concrete beam is extensively investigated using the scaled experimental specimens to identify the influence of prestressing force on the natural frequency because there are inconsistent analytical theories in the relationship between natural frequency and prestressing force of internally prestressed concrete beam. Three experimental specimens, i.e., the straight line of tendon with and without eccentricity and parabolic tendon profile are considered to investigate the dynamic behavior of internally prestressed concrete beam. Based on the experimental results, it is observed that the natural frequency is increased as tensile force of tendon is increased in the specimen with eccentricity, however, no meaningful relationship between natural frequency and tensile force could be found in the specimen without eccentricity. These results are related not only to the tensile force itself but also to the camber of the beam introduced by the tensile force. Therefore, it is difficult to establish the distinct relationship between natural frequency and tensile force. Instead, this relationship may be explained as dual effects of tendon on the natural frequency of beam, i.e., stiffening and softening effects. Therefore it is important to consider not only tensile force but also many other parameters such as tendon profile, camber of beam, boundary conditions, ratio of stiffness of concrete and tendon, and etc. for estimating the natural frequency or tensile force of the internally prestressed concrete beam.

다양한 해석적 방법에 의한 케이블 구조의 장력 추정

노명현,이상열,Noh, Myung-Hyun,Lee, Sang-Youl 한국복합신소재구조학회 2012 복합신소재구조학회논문집 Vol.3 No.3

The method based on various mathematical characteristic equations for identifying tensile forces in the cable structure system are used as response data to reflect the properties of the dynamic sensitivity. The vibration tests have been conducted with respect to levels of applied weight for the sagged cable. In this study, a set of natural frequencies are extracted from the measured dynamic data. Next, existing characteristic equation methods based these extracted natural frequencies are applied to identify tensil forces of the sagged cable system. Through several verification procedures, the proposed methods could be applied to a sagged cable system when the initial material data are insufficiency.

고에너지흡수 신소재 적용 해양플랜트 파형 방폭벽의 폭발 저항 성능

노명현,박규식,이재익 한국복합신소재구조학회 2015 복합신소재구조학회논문집 Vol.6 No.1

In this paper, a finite element dynamic simulation study was performed to gain an insight about the blast wall test details for the offshore structures. The simulation was verified using qualitative and quantitative comparisons for different materials. Based on in-depth examination of blast simulation recordings, dynamic behaviors occurred in the blast wall against the explosion are determined. Subsequent simulation results present that the blast wall made of high energy absorbing high manganese steel performs much better in the shock absorption. In this paper, the existing finite element shock analysis using the LS-DYNA program is further extended to study the blast wave response of the corrugated blast wall made of the high manganese steel considering strain rate effects. The numerical results for various parameters are verified by comparing different material models with dynamic effects occurred in the blast wall from the explosive simulation.

Free Vibration of Composite Shells Containing Embedded Delaminations based on the Third-order Shear Deformation Theory

노명현,이상열 대한토목학회 2012 KSCE JOURNAL OF CIVIL ENGINEERING Vol.16 No.7

The finite element vibration analysis of laminated spherical shell panels with rectangular embedded delamination is carried out based on the third-order shear deformation theory of Sanders. In the finite element formulation for the embedded delamination, the seven degrees of freedom per each node are used with transformations in order to fit the displacement continuity conditions at the delamination region. The numerical results obtained for plates and shells with delaminations are in good agreement with those of other preceding investigations. The new results for composite shell structures in this study mainly show the significant effect of the interactions between the radius-length ratio and other various parameters, for example, embedded delamination size, fiber angles, the number of layer and location of delamination in the layer direction

A parametric estimation of Richter-b and mmax from an earthquake catalog

노명현 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.3

Richter-b and mmax are, in general, estimated independently. However, when the two parameters are to be estimatedfrom an earthquake catalog by a parametric approach, they arelinked through a probabilistic density function so that the estimationof one parameter requires the value of the other. To solve thisproblem, the effect of one parameter on the estimation of the otherwas investigated with simulated earthquake catalogs. The investigationrevealed that the estimation of Richter-b was not sensitive tothe mmax value. An accurate enough Richter-b could be estimatedusing the observed maximum magnitude, mmax, of the earthquakecatalog. On the other hand, the estimation of mmax was quite sensitiveto b. The mmax estimate increases as the b value increases. Therefore, it is recommended to estimate b first using mmax andthen to estimate mmax using the b value that was just estimated. Inaddition, the efficiency of an iterative scheme was investigated. Itturned out that the iterative scheme further improves the b estimatewhen using mmax. This scheme also yields an mmax estimatecomparable to that obtained when using the true b value.

Multiple approaches based on synthetic biology for engineering Escherichia coli to produce coenzyme B12

노명현,임현규,박성훈,정규열 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Coenzyme B12 is one of the largest and the most structurally complicated chemical in nature. Due to its complex structure, B12 can be obtained only from native producers such as Pseudomonas denitrificans and Klebsiella pneumoniae. However, a lack of genetic engineering tool for these microorganisms limits us to further develop B12 high producer. Rather than engineering native producers, reconstruction of B12 pathway in genetically well-known microorganisms such as an Escherichia coli could be more conceivable to achieve high production. In this study, we applied multiple synthetic biology based approaches in E. coli. Initially, the genes for B12 biosynthesis in P. denitrificans were introduced; the genes were expressed under a strong promoter and optimized 5` untranslated regions (5`-UTR) for maximum expression. Then, an amplification of precursor pool and developing an efficient screening device allowed further strain improvement for increased B12 production.