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유한요소법을 이용한 단순인장 시험편의 탄소성파괴인성치 예측
선동주(D.J.Sun),박명균(M.K.Park),박세만(S.M.Bahk),최영택(Y.T.Choi) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.11_2
In oder to predict the elastic-plastic fracture toughness for metallic materials, Finite Element Method(FEM) was used for analysis of compact tension specimen. ASTM E399 test procedure was adopted for simulation of FEM. The Load-Crack Mouth Opening Displacement curve obtained from this analysis was used to detect the crack initiation point and determine the elastic-plastic fracture toughness J_IC. In order to prove the results, they were compared with the results from previous experiments and they agree with experimental results.
3차원 탄소성 유한요소법을 통한 금속복합재료와 지르코니아 접합체의 잔류응력해석
주재황,선동주,최영택,박세만,박명균 明知大學校 産業技術硏究所 1996 産業技術硏究所論文集 Vol.15 No.-
Employing a three dimensional finite element method a thermal elasto-plastic stress analysis was conducted to investigate residual stress distributions on the joining area between a ceramic(ZrO₂) and a SiC whisker-reinforced aluminum (Al composite). For purposes of comparisons, residual stresses at the interfaces on the joining area were first analyzed for varying volume fractions of SiC whiskers utilizing two dimensional elasto-plastic models. The results from the 2-D models were compared with those from 3-D models to understand the Practical nature of residual stresses produced during industrial joining processes for ceramics and metal matrix composites. Additionally, the same procedures were applied to compute stress variations along a line passing through the joining area to obtain a physical insight and to offer a plausible explanations for fracture patterns occuring at the interfaces during bending.
유한요소법을 이용한 금속재료의 탄소성파괴인성치 결정에 관한 연구
박명균,최영택,박세만,선동주 明知大學校 産業技術硏究所 1998 産業技術硏究所論文集 Vol.17 No.-
In oder to predict the elastic-plastic fracture toughness for metallic materials, Finite element Method(FEM) was used for analysis of compact tension specimen. ASTM E399 test procedure was adopted for simulation of FEM. The Load-Crack Mouth Opening Displacement curve obtained from this analysis was used to detect the crack initiation point and determine the elastic-plastic fracture toughness Jic. In order to prove the results, they were compared with the results from previous experiments and they agree with experimental results.
有限要素法을 이용한 열사이클 荷重壯態에서의 세라믹 /金屬 接合材의 强度 平價
최영택,박명균,박세만,선동주 明知大學校 産業技術硏究所 1998 産業技術硏究所論文集 Vol.17 No.-
In this work, variations of residual stresses are investigated by varying thicknesses of copper interlayers inserted for stress relaxations. Futhermore, various modes of stress distributions are evaluated under different assumptions of physical situations. departing from the simple assumption and adopting new assumption is judiciously made to study variations of residual stresses under the simple and new assumption, respectively. The simple assumption dictates that temperature distributions in the ceramic/metal joints are uniform, which amounts to longer cooling time (slow cooling), while the new assumption relaxes the condition of uniform temperature distributions allowing variations of temperatures in the ceramic/metal joints. Especially, the thermal cycles are applied to ceramic/metal joints retaining residual stresses developed during joining processes. Changes in distributions of residual stresses under the applied thermal cycles and the behavior of ceramic/ metal joints formed at elevated temperatures are evaluated from finite element analysis to produce results in good agreement with the existing experimental data.
AtBAG6, a novel calmodulin-binding protein, induces programmed cell death in yeast and plants
Kang, C H,Jung, W Y,Kang, Y H,Kim, J Y,Kim, D G,Jeong, J C,Baek, D W,Jin, J B,Lee, J Y,Kim, M O,Chung, W S,Mengiste, T,Koiwa, H,Kwak, S S,Bahk, J D,Lee, S Y,Nam, J S,Yun, D J,Cho, M J Nature Publishing Group 2006 CELL DEATH AND DIFFERENTIATION Vol.13 No.1
Calmodulin (CaM) influences many cellular processes by interacting with various proteins. Here, we isolated AtBAG6, an Arabidopsis CaM-binding protein that contains a central BCL-2-associated athanogene (BAG) domain. In yeast and plants, overexpression of AtBAG6 induced cell death phenotypes consistent with programmed cell death (PCD). Recombinant AtBAG6 had higher affinity for CaM in the absence of free Ca<SUP>2 +</SUP> than in its presence. An IQ motif (IQXXXRGXXXR, where X denotes any amino-acid) was required for Ca<SUP>2 +</SUP>-independent CaM complex formation and single amino-acid changes within this motif abrogated both AtBAG6-activated CaM-binding and cell death in yeast and plants. A 134-amino-acid stretch, encompassing both the IQ motif and BAG domain, was sufficient to induce cell death. Agents generating oxygen radicals, which are known to be involved in plant PCD, specifically induced the AtBAG6 transcript. Collectively, these results suggest that AtBAG6 is a stress-upregulated CaM-binding protein involved in plant PCD.Cell Death and Differentiation (2006) 13, 84–95. doi:10.1038/sj.cdd.4401712; published online 8 July 2005
Exposure assessment for Bacillus cereus in ready-to-eat Kimbab selling at stores
Bahk, G.J.,Todd, E.C.D.,Hong, C.H.,Oh, D.H.,Ha, S.D. Butterworths ; Taylor Francis ; Elsevier Science 2007 FOOD CONTROL Vol.18 No.6
Kimbab, which is rolled cooked-rice and other foodstuffs in dried laver, is a representative ready-to-eat (RTE) food in Korea. Bacillus cereus is a significant hazard associated with Kimbab. However, the knowledge of the dose-response relationship for B. cereus is limited, now it is not possible to conduct a full microbial risk assessment. Therefore, our study may be focused on the exposure assessment from retail store to the point of consumption in a Kimbab contaminated with B. cereus. The survey data for preparing and selling of Kimbab, predictive growth model, and consumer eating patterns were combined with probabilistic modeling to simulate the level of B. cereus in store Kimbab at the time of consumption. The estimated contamination levels ranged from as minimum (5% percentile) -3.63logcfu/g, median (50% percentile) 1.39logcfu/g, mean 1.57logcfu/g, and a maximum (95% percentile) 7.31logcfu/g. However, there is always a paucity of data to conduct such full exposure assessments with associated variability and uncertainty, coupled with a validation step. Therefore, we suggest that additional studies to allow for a more realistic and accuracy exposure assessment in the future, based on data gaps we identify.
Bahk, J.J.,Um, I.K.,Yi, B.Y.,Yoo, D.G. Pergamon Press 2016 QUATERNARY INTERNATIONAL Vol.392 No.-
<P>Cyclic variations of density and gamma-ray logs achieved from the two drill sites of UBGH2-1_1 and UBGH2-1_2 in the western slope of the Ulleung Basin were investigated to reveal their paleoceanographic implications and establish cyclostratigraphy of the well logs. Integration of the core, log, and seismic data from the two sites indicates that the sediments of the drilled intervals mostly consist of hemipelagic muds, with a few sporadic mass transport deposits intercalated only in the downslope site of UBGH2-1_1. Comparison with variations in sediment composition suggests that ratios of terrigeneous to biogenic materials which were modulated by orbital-scale climate changes should be responsible to the well-log variations. The established cyclostratigraphy of the well logs based on correlation with marine oxygen isotope records indicates such climatic modulation of the sedimentation in the western slope of the Ulleung Basin has persisted at least since 2.6 Ma, consistent with the variation reported from the Oki Ridge. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.</P>
Bahk, S. Y.,Chang, S. D.,Cheon, B. G.,Cho, J. H.,Jang, H. I.,Hahn, C. H.,Hara, T.,Lim, G. Y.,Kang, J. S.,Kim, C. O.,Kim, J. Y.,Kim, K. Y.,Kim, S. N.,Kim, T. I.,Kim, T. Y.,Koo, D. G.,Lee, S. B.,Lim, I. 慶尙大學校 기초과학연구소 1991 基礎科學硏究所報 Vol.7 No.-
An angular method of identifying diffractive excitation(DE) events for interactions of a hadron beam in nuclear emulsion is applied to identifying DE events in interactions of heavy ions beams. The "apparent" mean free paths (MEP) of DE processes for ^16O(^28Si) beams are 1.00±0.12, 2.4^_1.6_-0.7, and 2.2±0.4(1.5±0.2)m, respectively, at 200, 60 and 14.6 GeV/nucleon, which corresponds to 20-10% fo the MFP for total inelastic interactions. Distinctive features of diffractively excited nuclei are discussed.
Rice serine/threonine kinase 1 is required for the stimulation of OsNug2 GTPase activity
Heo, J.B.,Lee, Y.M.,Yun, H.R.,Im, C.H.,Lee, Y.S.,Yi, Y.B.,Kwon, C.,Lim, J.,Bahk, J.D. G. Fischer 2014 Journal of plant physiology Vol.171 No.17
Several GTPases are required for ribosome biogenesis and assembly. We recently identified rice (Oryza sativa) nuclear/nucleolar GTPase 2 (OsNug2), a YlqF/YawG family GTPase, as having a role in pre-60S ribosomal subunit maturation. To investigate the potential factors involved in regulating OsNug2 function, yeast two-hybrid screens were performed using OsNug2 as bait. Rice serine/threonine kinase 1 (OsSTK1) was identified as a candidate interacting protein. OsSTK1 appeared to interact with OsNug2 both in vitro and in vivo. OsSTK1 was found to have no effect on the GTP-binding activity of OsNug2; however, the presence of recombinant OsSTK1 in OsNug2 assay reaction mixtures increased OsNug2 GTPase activity. A kinase assay showed that OsSTK1 had weak autophosphorylation activity and strongly phosphorylated serine 209 of OsNug2. Using yeast complementation testing, we identified a GAL::OsNug2(S209N) mutation-harboring yeast strain that exhibited a growth-defective phenotype on galactose medium at 39<SUP>o</SUP>C, which was divergent from that of a yeast strain harboring GAL::OsNug2. The intrinsic GTPase activity of OsNug2(S209N), which was found to be similar to that of OsNug2, was not fully enhanced upon weak binding of OsSTK1. Our findings indicate that OsSTK1 functions as a positive regulator of OsNug2 by enhancing OsNug2 GTPase activity. In addition, phosphorylation of OsNug2 serine 209 is essential for its complete function in biological functional pathway.