• 항공우주시스템공학회지
• /
• 제1권2호
• /
• pp.27-36
• /
• 2007

The Damage Tolerant Design is developed to help alleviate structural failure and cracking problems in aerospace structures. Recently, the Damage Tolerant Design is required and recommended for most of aircraft design. In this paper, the damage tolerant design is applied to tilt rotor UAV. First of all, the fatigue load spectrum for the tilt rotor UAV is developed and fatigue analysis is performed for the flaperon joint which has FCL (fatigue critical location). Tilt rotor UAV has two modes: helicopter mode when UAV is taking off and landing; fixed wing mode when the tilt rotor UAV is cruising. To make fatigue load spectrum, FELIX is used for helicopter mode. TWIST is used for fixed wing mode. Fatigue analysis of flaperon joint is performed using fatigue load spectrum. E-N curve approach is used for picking crack initiation point. The LEFM(Linear Elastic Fracture Method) is considered for analyzing crack growth or propagation. Finally, including the crack initiation and propagation, the fatigue life is evaluated. Therefore the Damage Tolerant Design can be done.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.235-239
• /
• 1994

In this paper, the fatigue behaviour of typical axisymmetric forward extrusion die is investigated and extrusion process is analyzed by the rigid-plastic finite element method and elasto-plastic finite element method. To approach the crack problem involving crack initiation and propagation in extrusion die, LEFM(Linear Elastic Fracture Mechanics) is introduced and singular element which models stress.strain singularity in the crack tip vincity has been used to obtain an accurate stress intensityu factor values and other results. Form the displacement around the crack tip the stress intensity factor and the effective stress intensity factor at the beginning of the die inlet radius has been calculated. Applying proper fatigue crack propagation criterion such as Paris/Erdogan fatigue law to this data the angle and direction of fatigue crack growth has been simulated and these are compared with some experimental results. Using the computed crack growth rate, fatigue life of the extrusion die has been evaluated.

• 한국해양공학회지
• /
• 제13권1호통권31호
• /
• pp.1-10
• /
• 1999

The engine exhaustive valve became essential as the important element. The dissimmilar welding method of exhaustive valve head to stem was asked for manufacturing the engine exhaustive valve, for which the electric resistance are welding has been conventionally used, resulting in poor quality of the welded joint. In this paper, not only the development of optimizing of friction welding with more reliability and more applicability but also the development of in-process real-time weld qudlity(such as strength and toughness) evaluation technique by acoustic emission for friction welding of the engine exhaustive valve(SUH3-SUH35 dissimilar steels) were perfomed. The high temperature(500, 500, 600$^{circ}$C) creep properties prediction of the friction welded joint of SUH3-SUH35 was investigated relating to the initial strain meethod(ISM) as a new approach, resulting in obtaining an experimental equation of creep life prediction.

• Smart Structures and Systems
• /
• 제17권6호
• /
• pp.995-1015
• /
• 2016

In the design and condition assessment of bridges, it is usually necessary to take into consideration the extreme conditions which are not expected to occur within a short time period and thus require an extrapolation from observations of limited duration. Long-term structural health monitoring (SHM) provides a rich database to evaluate the extreme conditions. This paper focuses on the extrapolation of extreme traffic load effects on bridges using long-term monitoring data of structural strain. The suspension Tsing Ma Bridge (TMB), which carries both highway and railway traffic and is instrumented with a long-term SHM system, is taken as a testbed for the present study. Two popular extreme value extrapolation methods: the block maxima approach and the peaks-over-threshold approach, are employed to extrapolate the extreme stresses induced by highway traffic and railway traffic, respectively. Characteristic values of the extreme stresses with a return period of 120 years (the design life of the bridge) obtained by the two methods are compared. It is found that the extrapolated extreme stresses are robust to the extrapolation technique. It may owe to the richness and good quality of the long-term strain data acquired. These characteristic extremes are also compared with the design values and found to be much smaller than the design values, indicating conservative design values of traffic loading and a safe traffic-loading condition of the bridge. The results of this study can be used as a reference for the design and condition assessment of similar bridges carrying heavy traffic, analogous to the TMB.

• 마이크로전자및패키징학회지
• /
• 제10권1호
• /
• pp.45-50
• /
• 2003

시스템 보드에 플립 칩 BGA가 실장된 3차원 유한요소 해석 모델을 구성하여 열사이클시험 과정에서 발생되는 솔더 접합부의 피로수명을 예측하였다. 피로 모델은 Darveaux의 경험식에 기초하여 비선형 점소성 해석을 수행하였다. 해석은 4종류의 열사이클시험 조건과 패드구조, 솔더 볼의 조성과 크기의 변화에 따라 발생하는 크리프 수명을 평가하였다. 해석결과 $-65∼150^{\circ}C$의 열사이클시험 조건에서 가장 짧은 피로수명을 보였으며, $0∼100^{\circ}C$ 조건과 비교하면 약 3.5 배 정도 증가하였다. 동일한 시험조건에서 패드구조 변화에 따른 피로수명 차이는 SMD구조가 NSMD구조에 비해 약 5.7% 증가하였다 결과적으로 솔더 접합부에서 크리프 변형에너지 밀도가 높으면 피로수명은 짧아지는 것을 알 수 있었다

• The Plant Pathology Journal
• /
• 제24권2호
• /
• pp.191-201
• /
• 2008

Bacillus sp. SB-007 was isolated from pea leaves harvested from the southwestern parts of South Korea through screening on a minimal medium containing 0.2% purified cutin for its ability to induce the cutinase production. However, no cutinase was produced when it was grown in a minimal medium containing 0.2% glucose. A proteomic approach was applied to separate and characterize these differentially secreted proteins. The expression level of 83 extracellular proteins of the cutinase-producing Bacillus sp. strain SB-007 incubated in a cutinase-induced medium increased significantly as compared with that cultured in a non cutinase-induced medium containing glucose. The extracellular proteome of Bacillus sp. SB-007 includes proteins from different functional classes, such as enzymes for the degradation of various macromolecules, proteins involved in energy metabolism, sporulation, transport/binding proteins and lipoproteins, stress inducible proteins, several cellular molecule biosynthetic pathways and catabolism, and some proteins with an as yet unknown function. In addition, the two protein spots showed little similarities with the known lipolytic enzymes in the database. These secreted proteome analysis results are expected to be useful in improving the Bacillus strains for the production of industrial cutinases.

• 한국축산식품학회지
• /
• 제44권1호
• /
• pp.39-50
• /
• 2024

The projected growth of global meat production over the next decade is attributed to rising income levels and population expansion. One potentially more pragmatic approach to mitigating the adverse externalities associated with meat production involves implementing alterations to the production process, such as transitioning to cultured meat, hybrid cultured meat, and meat alternatives. Cultured meat (CM) is derived from animal stem cells and undergoes a growth and division process that closely resembles the natural in vivo cellular development. CM is emerging as a widely embraced substitute for traditional protein sources, with the potential to alleviate the future strain on animalderived meat production. To date, the primary emphasis of cultured meat research and production has predominantly been around the ecological advantages and ethical considerations pertaining to animal welfare. However, there exists substantial study potential in exploring consumer preferences with respect to the texture, color, cuts, and sustainable methodologies associated with cultured meat. The potential augmentation of cultured meat's acceptance could be facilitated through the advancement of a wider range of cuts to mimic real muscle fibers. This review examines the prospective commercial trends of hybrid cultured meat. Subsequently, the present state of research pertaining to the advancement of scaffolding, coloration, and muscle fiber development in hybrid cultured meat, encompassing plant-based alternatives designed to emulate authentic meat, has been deliberated. However, this discussion highlights the obstacles that have arisen in current procedures and proposes future research directions for the development of sustainable cultured meat and meat alternatives, such as plant-based meat production.

• Journal of Microbiology and Biotechnology
• /
• 제23권4호
• /
• pp.444-450
• /
• 2013

A Gram-negative, strictly aerobic, non-motile, non-spore-forming, and rod-shaped bacterial strain designated FW-$6^T$ was isolated from a freshwater sample and its taxonomic position was investigated by using a polyphasic approach. Strain FW-$6^T$ grew optimally at $10-42^{\circ}C$ and at pH 7.0 on nutrient and R2A agar. Strain FW-$6^T$ displayed ${\beta}$-glucosidase activity that was responsible for its ability to transform ginsenoside $Rb_1$ (one of the dominant active components of ginseng) to Rd. On the basis of 16S rRNA gene sequence similarity, strain FW-$6^T$ was shown to belong to the family Sphingomonadaceae and was related to Novosphingobium aromaticivorans DSM $12444^T$ (98.1% sequence similarity) and N. subterraneum IFO $16086^T$ (98.0%). The G+C content of the genomic DNA was 64.4%. The major menaquinone was Q-10 and the major fatty acids were summed feature 7 (comprising $C_{18:1}{\omega}9c/{\omega}12t/{\omega}7c$), summed feature 4 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2OH$), $C_{16:0}$, and $C_{14:0}$ 2OH. DNA and chemotaxonomic data supported the affiliation of strain FW-$6^T$ to the genus Novosphingobium. Strain FW-$6^T$ could be differentiated genotypically and phenotypically from the recognized species of the genus Novosphingobium. The isolate that has ginsenoside converting ability therefore represents a novel species, for which the name Novosphingobium ginsenosidimutans sp. nov. is proposed, with the type strain FW-$6^T$ (= KACC $16615^T$ = JCM $18202^T$).

• 소성∙가공
• /
• 제11권4호
• /
• pp.355-362
• /
• 2002

In this study, an axi-symmetric finite element program for elastic analysis of the die set shrink fitted in cold extrusion was developed. The geometrical constraint according to shrink fit was enforced by employing the Lagrange multiplier method. The numerical results for strain and stress distributions in the die set including single and multi stress rings assembled by shrink fit were compared well with the Lame's equation for thick-walled solution available in the literature. To extend the applicability of the analysis program developed, various cases without or with stress ring and with pre-stress applied on stress ring were numerically investigated as well. This numerical approach enables the optimization study to determine optimal dimensions of die set to improve tool life for practical use in industry.

• 생명과학회지
• /
• 제34권2호
• /
• pp.79-85
• /
• 2024

SlyA는 Salmonella와 같은 장내세균과(Enterobacteriaceae)에 속하는 E. coli에서 용혈소(HlyE)의 발현을 조절하는 전사 조절인자로 알려져 있다. 그러나 Salmonella에는 slyA 유전자가 있지만 hlyE 유전자는 없다. Salmonella에서 SlyA의 역할을 탐구하기 위해 slyA 유전자가 결실된 돌연변이주를 사용하였다. S. Typhimurium CK295 (ΔslyA)는 allelic exchange 방법으로 제작되었다. 야생형 균주와 CK295 균주의 비교시험에서 생육 특성, 운동성, 총 단백질 분석, 분비 단백질 분석 등에서 특별한 차이가 발견되지 않았다. CK295 균주는 야생형에 비해 생물막을 약간 적게 생성하는 패턴을 보였다. 흥미롭게도, 대식세포에서의 생존능력을 비교한 결과, CK295 균주는 야생형에 비해 생존능력이 60% 감소하는 것으로 나타났다. 마우스의 독성을 테스트하기 위해 6주령 BALB/c 마우스에 경구 투여한 후 사망률을 측정하였다. 그 결과, BALB/c에서 CK295 (ΔslyA)의 LD₅₀ 값이 야생형 S. Typhimurium 𝜒3339의 값보다 100배 이상 높게 나타났다. 종합적으로, SlyA는 살모넬라균의 in vivo 생존에 관여하는 독성 인자를 코딩하는 유전자의 발현을 조절하는 것으로 추정된다.