야웨는 어떻게 만국의 왕이 되었나?

라인하르트 아헨바흐(Reinhard Achenbach),이영미(번역자) 한신대학교 한신신학연구소 2023 신학연구 Vol.60 No.2

Use of the reciprocity theorem for a closed form solution of scattering of the lowest axially symmetric torsional wave mode by a defect in a pipe

Lee, Jaesun,Achenbach, Jan D.,Cho, Younho Elsevier 2018 Ultrasonics Vol.84 No.-

<P><B>Abstract</B></P> <P>Guided waves can effectively be used for inspection of large scale structures. Surface corrosion is often found as major defect type in large scale structures such as pipelines. Guided wave interaction with surface corrosion can provide useful information for sizing and classification. In this paper, the elastodynamic reciprocity theorem is used to formulate and solve complicated scattering problems in a simple manner. The approach has already been applied to scattering of Rayleigh and Lamb waves by defects to produce closed form solutions of amplitude of scattered waves. In this paper, the scattering of the lowest axially symmetric torsional mode, which is widely used in commercial applications, is analyzed by the reciprocity theorem. In the present paper, the theorem is used to determine the scattering of the lowest torsional mode by a tapered defect that was earlier considered experimentally and numerically by the finite element method. It is shown that by the presented method it is simple to obtain the ratio of amplitudes of scattered torsional modes for a tapered notch. The results show a good agreement with earlier numerical results. The wave field superposition technique in conjunction with the reciprocity theorem simplifies the solution of the scattering problem to yield a closed form solution which can play a significant role in quantitative signal interpretation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The scattering of the lowest torsional mode is analyzed by the reciprocity theorem. </LI> <LI> The solution of wave scattering amplitude ratio is presented in simple form. </LI> <LI> The presented method is simple to obtain the scattered amplitude compared to FEM. </LI> <LI> This results can play a significant role in quantitative signal interpretation. </LI> </UL> </P>

Detection of Second-Layer Corrosion in Aging Aircraft Fuselage

Nohyu Kim,J. D. Achenbach 한국비파괴검사학회 2006 한국비파괴검사학회지 Vol.26 No.6

횡방향 전단하중을 받는 단일방향 복합재료의 미시역학적 거동연구

최흥섭,Choi, Heung-Soap,Achenbach, J.D. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.11

Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio $V_f$ and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of $V_f$ increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of $V_f$ slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.

Detection of Second-Layer Corrosion in Aging Aircraft Fuselage

Kim, Noh-Yu,Achenbach, J.D. The Korean Society for Nondestructive Testing 2006 한국비파괴검사학회지 Vol.26 No.6

A Digital X-ray imaging system using Compton backscattering has been developed to obtain a cross-sectional profile and mass loss of corroded lap-splices of aging aircraft from density variation. A slit-type camera was designed to focus on a small scattering volume inside the material, from which the backscattered photons are collected by a collimated scintillator detector for interpretation of material characteristics. The cross section of the lap-joint is scanned by moving the scattering volume through the thickness direction of the specimen. The mass loss of each layer has been estimated from a Compton backscatter A-scan to obtain the thickness of each layer including the aluminum sheet, the corrosion layer and the sealant. Quantitative information such as location and width of planar corrosion in the lap splices of fuselages is obtained by deconvolution using a nonlinear least-square error minimization method(BFGS method): A simple reconstruction model is also introduced to overcome distortion of the Compton backscatter data due to attenuation effects attributed to beam hardening and quantum noise.

Genetic characterization of African swine fever virus in Cameroon, 2010–2018

Abel Wade,Jenna Elizabeth Achenbach,Carmina Gallardo,Tirumala Bharani K. Settypalli,Abdoulkadiri Souley,Gaston Djonwe,Angelika Loitsch,Gwenaelle Dauphin,Jean Justin Essia Ngang,Onana Boyomo,Giovanni C 한국미생물학회 2019 The journal of microbiology Vol.57 No.4

African swine fever (ASF) is a highly lethal haemorrhagic disease in domestic and wild swine that has acquired great importance in sub-Saharan Africa since 1997. ASF was first reported in Cameroon in 1982 and was detected only in Southern Cameroon (South, West, East, Northwest, Southwest, Littoral, and Centre regions) until February 2010 when suspected ASF outbreaks were reported in the North and Far North regions. We investigated those outbreaks by analysing samples that were collected from sick pigs between 2010 and 2018. We confirmed 428 positive samples by ELISA and realtime PCR and molecularly characterized 48 representative isolates. All the identified virus isolates were classified as ASFV genotype I based on the partial B646L gene (C-terminal end of VP72 gene) and the full E183L gene encoding p54 protein analysis. Furthermore, analysis of the central variable region (CVR) within the B602L gene demonstrated that there were 3 different variants of ASFV genotype I, with 19, 20, and 21 tetrameric tandem repeat sequences (TRSs), that were involved in the 2010–2018 outbreaks in Cameroon. Among them, only variant A (19 TRSs) was identical to the Cam/82 isolate found in the country during the first outbreaks in 1981–1982. This study demonstrated that the three variants of ASFV isolates involved in these outbreaks were similar to those of neighbouring countries, suggesting a movement of ASFV strains across borders. Designing common control measures in affected regions and providing a compensation programme for farmers will help reduce the incidence and spread of this disease.

제 4 학술분과 : 누설 초음파 표면파를 이용한 금속복합재료의 초기피로 손상평가

이준현,J . D . Achenbach 한국복합재료학회 1992 한국복합재료학회 학술발표회 논문초록집 Vol.- No.2

Study on the scattering of 2-D Rayleigh waves by a cavity based on BEM simulation

Weiwei Liu,조윤호,PHANHAI DANG,Jan D. Achenbach 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.3

A frequency domain boundary element method is introduced in this paper to simulate the scattering of two-dimensional Rayleigh waves by a cavity on the surface of an elastic half-space. This numerical method allows the Rayleigh wave to escape the truncated boundary without producing any spurious reflections. The numerical results of the displacements and stresses of a 2-D Rayleigh wave which travels along a flat surface of an elastic half-infinite medium are in good agreement when compared with theoretical ones. The problem of a Rayleigh wave scattering by a cavity on the surface of an elastic half-infinite medium is simulated by the proposed numerical method. The result is taken as the benchmark to introduce an approximate analytical method for such problems of scattering by a cavity on the surface. This numerical method is formulated for a two-dimensional homogeneous, isotropic, linearly elastic half-space and its implementation in a frequency domain boundary scheme is discussed in detail.

Prognostic value of chronic total occlusions detected on coronary computed tomographic angiography

Opolski, Maksymilian P,Gransar, Heidi,Lu, Yao,Achenbach, Stephan,Al-Mallah, Mouaz H,Andreini, Daniele,Bax, Jeroen J,Berman, Daniel S,Budoff, Matthew J,Cademartiri, Filippo,Callister, Tracy Q,Chang, Hy BMJ Group 2019 Heart Vol.105 No.3

<P><B>Objective</B></P><P>Data describing clinical relevance of chronic total occlusion (CTO) identified by coronary CT angiography (CCTA) have not been reported to date. We investigated the prognosis of CTO on CCTA.</P><P><B>Methods</B></P><P>We identified 22 828 patients without prior known coronary artery disease (CAD), who were followed for a median of 26 months. Based on CCTA, coronary lesions were graded as normal (no atherosclerosis), non-obstructive (1%–49%), moderate-to-severe (50%–99%) or totally occluded (100%). All-cause mortality, and major adverse cardiac events defined as mortality, non-fatal myocardial infarction and late coronary revascularisation (≥90 days after CCTA) were assessed.</P><P><B>Results</B></P><P>The distribution of patients with normal coronaries, non-obstructive CAD, moderate-to-severe CAD and CTO was 10 034 (44%), 7965 (34.9%), 4598 (20.1%) and 231 (1%), respectively. The mortality rate per 1000 person-years of CTO patients was non-significantly different from patients with moderate-to-severe CAD (22.95; 95% CI 12.71 to 41.45 vs 14.46; 95% CI 12.34 to 16.94; p=0.163), and significantly higher than of those with normal coronaries and non-obstructive CAD (p<0.001 for both). Among 14 382 individuals with follow-up for the composite end point, patients with CTO had a higher rate of events than those with moderate-to-severe CAD (106.56; 95% CI 76.51 to 148.42 vs 65.45; 95% CI 58.01 to 73.84, p=0.009). This difference was primarily driven by an increase in late revascularisations in CTO patients (27 of 35 events). After multivariable adjustment, compared with individuals with normal coronaries, the presence of CTO conferred the highest risk for adverse cardiac events (14.54; 95% CI 9.11 to 23.20, p<0.001).</P><P><B>Conclusions</B></P><P>The detection of CTO on non-invasive CCTA is associated with increased rate of late revascularisation but similar 2-year mortality as compared with moderate-to-severe CAD.</P><P><B>Trial registration number</B></P><P> NCT01443637.</P>

Assessment of Heat Treated Inconel X-750 Alloy by Nonlinear Ultrasonics

Li, W.,Cho, Y.,Lee, J.,Achenbach, J. D. Springer-Verlag 2013 Experimental mechanics Vol.53 No.5