• Journal of Animal Science and Technology
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• 제63권6호
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• pp.1411-1422
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• 2021

Lactobacillus acidophilus is a gram-positive, microaerophilic, and acidophilic bacterial species. L. acidophilus strains in the gastrointestinal tracts of humans and other animals have been profiled, but strains found in the canine gut have not been studied yet. Our study helps in understanding the genetic features of the L. acidophilus C5 strain found in the canine gut, determining its adaptive features evolved to survive in the canine gut environment, and in elucidating its probiotic functions. To examine the canine L. acidophilus C5 genome, we isolated the C5 strain from a Korean dog and sequenced it using PacBio SMRT sequencing technology. A comparative genomic approach was used to assess genetic relationships between C5 and six other strains and study the distinguishing features related to different hosts. We found that most genes in the C5 strain were related to carbohydrate transport and metabolism. The pan-genome of seven L. acidophilus strains contained 2,254 gene families, and the core genome contained 1,726 gene families. The phylogenetic tree of the core genes in the canine L. acidophilus C5 strain was very close to that of two strains (DSM20079 and NCFM) from humans. We identified 30 evolutionarily accelerated genes in the L. acidophilus C5 strain in the ratio of non-synonymous to synonymous substitutions (dN/dS) analysis. Five of these thirty genes were associated with carbohydrate transport and metabolism. This study provides insights into genetic features and adaptations of the L. acidophilus C5 strain to survive the canine intestinal environment. It also suggests that the evolution of the L. acidophilus genome is closely related to the host's evolutionary adaptation process.

• 대한기계학회논문집
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• 제9권2호
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• pp.140-149
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• 1985

본 연구는 오오스테나이트계 STS 316 스테인레스강에 대하여 온도 550.deg. C의 대 기중에서, 변형율제어에 의한 인장-압축에 크리이프 유지시간을 갖는 고온저사이클 피 로시험을 하여 변형율폭 및 크리이프 유지시간이 피로수명에 미치는 영향과 파단면을 주사형 전자현미경으로 관찰하여 크리이프-피로 상호작용이 피로파단면에 미치는 크리 이프 효과를 실험 고찰하였다.

• Journal of Welding and Joining
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• 제23권3호
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• pp.68-75
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• 2005

The fatigue life of welded joints is associated with crack initiation and propagation life. Theses cannot be easily separated, since the definition of crack initiation is vague due to the initiation of multiple cracks that are distributed randomly along the weld toes. In this paper a method involving a notch strain and fracture mechanical approach, which considers the characteristics of welded joints, e.g. welding residual stress and statistical characteristics of multiple cracks, is proposed, in an attempt to reasonably estimate these fatigue lives. The fatigue crack initiation life was evaluated statistically, e.g. the probability of failure occurrence in 2.3, 50 and $97.7\%$, in which the cyclic response of the local stress/strain hi the vicinity of the weld toes and notch factors derived by the irregular shape of the weld bead are taken into account. The fatigue crack propagation life was simulated by using Monte-Carlo method in consideration of the Ad-factor and the mechanical behavior of mutual interaction/coalescence between two adjacent cracks. The estimated total fatigue life, $(N_T)_{P50\%}$, as a sum of crack initiation and propagation life under the probability of failure occurrence in $50\%$ showed a good agreement with the experimental results. The developed technique for fatigue lift estimation enables to provide a quantitative proportion of crack initiation and propagation life in the total fatigue life due to the nominal stress range, ${\Delta}S$.

• 한국균학회지
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• 제38권1호
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• pp.34-39
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• 2010

느티만가닥버섯의 품종구분을 위하여 국내 버섯보존기관으로부터 수집한 30종의 품종에 대한 RAPD 분석을 실시하였다. 이를 위하여 고체배지상의 균사로부터 염색체 DNA를 분리하였고 이를 주형으로 하여 3개의 random primer로 PCR 반응을 수행하였다. 그 결과 각 PCR 반응에서 200 bp에서 3000 bp 범위의 크기를 가진 DNA 밴드 약 30종이 관찰되었다. DNA 밴드 패턴은 UPGMA 방법으로 분석하여 그 결과를 dentrogram으로 나타내었다. 느티만가닥버섯은 2개의 클러스터로 분석되었으며, 클러스터 1은 다시 3개의 작은 그룹으로 나눌 수 있었다. 반면, 클러스터 2의 경우에는 유전적으로 클러스터 1보다 다양한 품종으로 구성되어 있었다. 흥미롭게도 덕유산에서 채집된 야생종 Hm3-10의 경우 어느 클러스터에도 속하지 않는 고유의 품종임을 확인하였다. RAPD 결과 나타나는 품종별 고유의 DNA 밴드를 품종특이적 마커로 개발하기 위하여, Hm0-4 품종의 250 bp 특이밴드를 TA-클로닝하고 염기서열을 결정하였다. 결정된 염기서열을 바탕으로 PCR primer를 디자인하였고 이를 이용하여 PCR 반응을 수행하였다. 그 결과 250 bp DNA 밴드는 Hm0-4 품종에서만 관찰되었으며 이는 이러한 접근법이 품종특이적 마커개발에 잘 적용됨을 보여주는 것이다.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.44-51
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• 2001

One of the recent issues in design of the spot-welded structure such as the automobile body is to develop an economical prediction method of the fatigue design criterion without additional fatigue test. In this paper, as one of basic investigation for developing such methods, fracture mechanical approach was investigated. First, the Model I, Mode II and Mode III, stress intensity factors were analyzed. Second, strain energy density factor (S) synthetically including them was calculated. And finally, in order to decide the systematic fatigue design criterion by using this strain energy density factor, fatigue data of the ΔP-N(sub)f obtained on the various in-plane bending type spot-welded lap joints were systematically re-arranged in the ΔS-N(sub)f relation. And its utility and reliability were verified by the theory of Weibull probability distribution function. The reliability of the proposed fatigue life prediction value at 10(sup)7 cycles by the strain energy density factor was estimated by 85%. Therefore, it is possible to decide the fatigue design criterion of spot-welded lap joint instead of the ΔP-N(sub)f relation.

• 한국정밀공학회지
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• 제24권4호
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• pp.123-130
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• 2007

Recently, a lot of work and interest have been devoted to the development of multiaxial fatigue parameters for fretting fatigue life prediction. In this study, the fretting fatigue lift and critical location ware estimated and evaluated through the multiaxial fatigue theories in a cylinder-on-flat contact configuration far Cr-Mo steel, SCM420, the material commonly is used in gears of the automobile and rollers of the conveyor. The strain-life curve was obtained from fatigue test for SCM420. The Fretting fatigue life and critical location were estimated through stress distributions, SWT-parameters and FS-parameters obtained from FEA. This paper showed possibility of applying multiaxial fatigue theories to fretting fatigue lift prediction comparing predicted life with experimental results.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.27-32
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• 2002

In this paper, global full 3D finite element analysis fatigue models are constructed for flip-chip BGA on board to predict the creep fatigue life of solder joints during the thermal cycling test. The fatigue model applied is based on Darveaux's empirical equation approach with non-linear viscoplastic analysis of solder joints. It was estimated by the creep life as the variations of the four kinds of thermal cycling test conditions, pad structure, composition and size of solder ball. The shortest fatigue life of results was obtained at the thermal cycling testing condition of -65℃ ∼ 150℃. It was increased about 3.5 times in comparison with that of 0℃ ∼ 100℃. As the change of pad structure at the same other conditions, the fatigue life of SMD structure increased about 5.7% as compared with NSMD structure. Consequently, it was confirmed that the fatigue life became short as the creep strain energy density increased in solder joint.

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.913-918
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• 2007

A Gram-positive, aerobic, rod-shaped, nonmotile, endospore-forming bacterium, designated Gsoil $349^T$, was isolated from soil of a ginseng field and characterized using a polyphasic approach. Comparative analysis of 16S rRNA gene sequences revealed that the strain Gsoil $349^T$ belongs to the family Paenibacillaceae, and the sequence showed closest similarity with Cohnella thermotolerans DSM $17683^T$ (94.1%) and Cohnella hongkongensis DSM $17642^T$ (93.6%). The strain showed less than 91.3% 16S rRNA gene sequence similarity with Paenibacillus species. In addition, the presence of MK-7 as the major menaquinone and $anteiso-C_{15:0},\;iso-C_{16:0},\;and\;C_{16:0}$ as major fatty acids suggested its affiliation to the genus Cohnella. The G+C content of the genomic DNA was 53.4 mol%. On the basis of its phenotypic characteristics and phylogenetic distinctiveness, strain Gsoil $349^T$ should be treated as a novel species within the genus Cohnella for which the name Cohnella panacarvi sp. nov. is proposed. The type strain is Gsoil $349^T\;(=KCTC\;13060^T=\;DSM\;18696^T)$.

• Journal of Hydrospace Technology
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• 제2권2호
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• pp.80-87
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• 1996

A creep-buckling analysis is studied for a simply-supported viscoelastic column. The fluid-type four-parameter model is employed because of its general applicability to creep materials. Using the imperfection-based incremental approach, a nonlinear load deflection equation is derived. Safe load and critical (or life) time which characterize the stability of the viscoelastic column are obtained mathematically and interpreted physically. A finite difference algorithm is applied to solve the second-order differential equation of the viscoelastic stress-strain relation. Numerical calculation has been made and discussed far a SUS316 stainless steel column.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2009년도 International Meeting of the Microbiological Society of Korea
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• pp.78-78
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• 2009

$^1H$ NMR spectroscopy coupled with multivariate statistical analysis was used for the first time to investigate metabolic changes in musts during alcoholic fermentation and wines during ageing. Three Saccharomyces cerevisiae yeast strains (RC-212, KIV-1116 and KUBY-501) were also evaluated for their impacts on the metabolic changes in must and wine. Pattern recognition (PR) methods, including PCA, PLS-DA and OPLS-DA scores plots, showed clear differences for metabolites among musts or wines for each fermentation stage up to 6 months. Metabolites responsible for the differentiation were identified to valine, 2,3-butanediol (2,3-BD), pyruvate, succinate, proline, citrate, glycerol, malate, tartarate, glucose, N-methylnicotinic acid (NMNA), and polyphenol compounds. PCA scores plots showed continuous movements away from days 1 to 8 in all musts for all yeast strains, indicating continuous and active fermentation. During alcoholic fermentation, highest levels of 2,3-BD, succinate and glycerol were found in musts with the KIV-1116 strain, which showed the fastest fermentation or highest fermentative activity of the 3 strains, whereas the KUBY-501 strain showed the slowest fermentative activity. This study highlights the applicability of NMR-based metabolomics for monitoring wine fermentation and evaluating the fermentative characteristics of yeast strains.