• 화약ㆍ발파
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• 제26권1호
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• pp.7-14
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• 2008

사일로와 같은 대단면 원통형 구조물을 전도시키기 위해서는 구조적 특성 및 사전 취약화를 위한 개구부의 조건을 고려하여 설계해야 한다. 본 연구에서는 원통형 구조물을 전도시키기 위해 구조적으로 동일한 원통형 구조물을 상용해석 프로그램인 3D AEM으로 모델링하여, 개구부의 조건으로는 개구부의 높이, 개구부의 각도, 개구부의 형태를 변수로 설정하여 이들 변수에 따른 원통형 구조물의 전도 붕괴 거동을 모사하고 분석하였다.

• Computers and Concrete
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• 제23권2호
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• pp.121-131
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• 2019

Due to the heterogeneity nature of the concrete, it is difficult to simulate the hyperdynamic behaviour and crack trajectory of concrete material when subjected to explosion loads. In this paper, a 3D nonlinear numerical study was conducted to simulate the hyperdynamic behaviour of concrete under various loading conditions using Riedel-Hiermaier-Thoma (RHT) model. Detailed calibration was conducted to identify the optimal parameters for the RHT model on the material level. For the component level, the calibrated RHT parameters were used to simulate the failure behaviour of plain concrete (PC) slab under free air blast load. The response was compared with an available experimental result. The results show the proposed numerical model can accurately simulate the crack trajectory and the failure mode of the PC slab under free air blast load.

• The Plant Pathology Journal
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• 제33권1호
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• pp.21-33
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• 2017

Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (Citrus reticulata) in Montenegro, using multilocus sequence analysis of gyrB, rpoD, and gap1 gene sequences. Gene sequences from a collection of 54 reference pathotype strains of P. syringae from the Plant Associated and Environmental Microbes Database (PAMDB) was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of gyrB, rpoD, and gap1 gene sequences showed that P. syringae pv. syringae causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for P. syringae control.

• The Plant Pathology Journal
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• 제33권1호
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• pp.9-20
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• 2017

Incidence of leaf blast on nursery plants and pitting disease on maturing banana bunches has been recorded in banana plantations during rainy season in Eastern India during 2014 to 2015. Taxonomical identification as well as DNA sequence analysis of the internal transcribed spacer region of fungus isolated from affected tissue culture derived plantlets and fruits confirmed the pathogen to be Pyricularia angulata Hashioka "in both the cases". Koch's postulates were proved on young plantlets as well as on maturing fruits of cv. Grand Naine under simulated conditions. Evolutionary history was inferred and presented for our P. angulata strain PG9001 with GenBank accession no. KU984740. The analysis indicated that the P. angulata is phylogenitically distinct from other related species related to both Pyricularia and Magnaporthe. Detailed symptoms of blast lesions on young leaves, transition leaves, mid rib, petioles, peduncle, maturing bunches, bunch stalks and cushions were documented. Notably, the distinct small pitting spots on maturing bunches reduced the visual appeal of mature fruits. Appearance of pitting symptoms on fruits in relation with age of fruits and their distribution pattern on bunch and fingers was also documented in detail. Further, the roles of transitory leaves, weed hosts, seasonality on disease occurrence have also been documented.

• 터널과지하공간
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• 제13권4호
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• pp.316-320
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• 2003

본 연구에서는 불규칙한 천공장이 발파진동에 미치는 영향에 관하여 연구하였다. 각각 2.lm 2.3m, 2.4m의 천공장에 대한 최대 진동속도와 삼승근환산거리의 관계를 비교 분석한 결과동일 환산거리에서 천공장의 크기가 길어질수록 더 큰 진동속도를 보였다. 그러므로 허용진동 속도이하의 일정범위의 발파 진동치를 유지하기 위하여서는 규clr적인 천공이 되도록 관리가 필요할 것으로 판단된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.463-470
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• 2000

In tunnel excavation by blast beneath the surface structures in urban area, the characteristics of ground vibration induced by blast and its influence on surface structures are analyzed by the field test and the numerical analysis on dynamic behaviors of the structure. According to the field test on the propagating characteristics of blast vibration through the rock mass and the concrete foundation pile. the attenuation index of peak particle velocity with distance shows the range of 1.7∼2.0 for the rock mass and the range of 2.0∼2.3 for the concrete pile. This shows that the blast vibration reduces more rapidly in the concrete pile. It is known from the numerical analysis on dynamic behavior of the structure that the coefficient of response, velocity ratio of structure response to input wave, is different according to the story of the structure. It can be said from this research that the characteristics of the ground vibration and the dynamic behavior of the structure should be well evaluated and be considered as important factors for safe blasting design especially in underground excavation at shallow depth in urban area.

• Structural Engineering and Mechanics
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• 제45권6호
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• pp.803-819
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• 2013

This paper addresses two main issues relevant to the structural assessment of buildings subjected to explosions. The first issue regards the robustness evaluation of steel frame structures: a procedure is provided for computing "robustness curves" and it is applied to a 20-storey steel frame building, describing the residual strength of the (blast) damaged structure under different local damage levels. The second issue regards the precise evaluation of blast pressures acting on structural elements using Computational Fluid Dynamic (CFD) techniques. This last aspect is treated with particular reference to gas explosions, focusing on some critical parameters (room congestion, failure of non-structural walls and ignition point location) which influence the development of the explosion. From the analyses, it can be deduced that, at least for the examined cases, the obtained robustness curves provide a suitable tool that can be used for risk management and assessment purposes. Moreover, the variation of relevant CFD analysis outcomes (e.g., pressure) due to the variation of the analysis parameters is found to be significant.

• Structural Engineering and Mechanics
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• 제77권5호
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• pp.613-626
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• 2021

In this paper, an enhanced Violation-based Sensitivity analysis and Border-Line Adaptive Sliding Technique (ViS-BLAST) will be utilized for optimization of some well-known structural and mechanical engineering problems. ViS-BLAST has already been introduced by the authors for solving truss optimization problems. For those problems, this method showed a satisfactory enactment both in speed and efficiency. The Enriched ViS-BLAST or EVB is introduced to be vastly applicable to any solvable constrained optimization problem without any specific initialization. It uses one-directional step-wise searching technique and mostly limits exploration to the vicinity of FNF border and does not explore the entire design space. It first enters the feasible region very quickly and keeps the feasibility of solutions. For doing this important, EVB groups variables for specifying the desired searching directions in order to moving toward best solutions out or inside feasible domains. EVB was employed for solving seven numerical engineering design problems. Results show that for problems with tiny or even complex feasible regions with a larger number of highly non-linear constraints, EVB has a better performance compared to some records in the literature. This dominance was evaluated in terms of the feasibility of solutions, the quality of optimum objective values found and the total number of function evaluations performed.

• 한국전산구조공학회논문집
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• 제37권3호
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• pp.179-186
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• 2024

본 논문에서는 충격파 형태의 폭발 하중을 받는 부재의 소성 범위를 고려한 SDOF 해석의 수정계수를 개발하였다. SDOF 해석의 수정계수는 MDOF 해석 결과 값을 비교하여 도출하였다. SDOF 해석에 영향을 미치는 매개변수로 부재의 경계조건, 폭발 하중 지속시간과 고유주기 비를 선정하였다. 수정계수는 탄성 하중-질량 변환 계수를 기준으로 산정하였다. 수정계수 곡선은 상한, 하한 매개변수 경계 사이에 있도록 타원 방정식을 이용하여 도출하였다. 서로 다른 단면과 경계조건을 가지는 예제에 수정계수를 적용한 결과 SDOF 해석의 오차율이 15%에서 3%로 감소하였다. 본 연구의 결과는 수정계수를 적용하여 SDOF 해석의 정확도를 높임에 따라 폭발 해석에 널리 활용될 수 있다.

• 한국전산유체공학회지
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• 제10권4호통권31호
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• pp.59-65
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• 2005

A numerical analysis was made to investigate the simple silencer for high pressure blast flow fields. Reynolds-Averaged Navier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block grids. A blast flow field without the silencer was also calculated to validate the present numerical method. The effect of pressure diminution for the silencer was calculated by comparing with and without silencer at the atmosphere region. It was found that the tested silencer could achieve 89.4 percent pressure diminution.