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Application of Frictional Bond-Slip Model to Large-Scale FRP-Strengthened T-Beams with U-wraps
Jaeha Lee,Maria Lopez 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.1
Studies on U-wraps generally focus on the experimental results and mechanisms of the shear strengthening effect. Only a few studies have focused on the anchoring effect of the longitudinal FRP due to addition of the U-wrap. Lee and Lopez (Constr Build Mater 194:226–237, 2016) have found experimentally from pull-out tests that incremental changes occur in the debonding strain at the concrete-FRP interface depending on the various type of U-wraps. The proposed numerical method using the Frictional Bond-Slip (FBS) model has been validated by comparing the pull-out test results (Lee and Lopez Constr Build Mater 194:226–237, 2016). In the present study, the FBS model was applied to characterize the behavior of a large scale FRP strengthened T-beam with multiple U-wraps. First, the 2-dimensional (2D) model for pull-out test was developed. Debonding load and behavior of the model were compared with both the experimental results (Lee and Lopez Constr Build Mater 194:226–237, 2016) and the simulation results of a 3-dimensional (3D) model from a previous study (Lee and Lopez Constr Build Mater 194:226-237, 2016). Next, the 2D model was applied to model the behavior of a large scale FRP strengthened T-beam with multiple U-wraps. The conducted 2D simulation using the proposed FBS model predicted well the strains at various locations on the FRP sheet, the flexural capacity and complex failure mode of the FRP strengthened beam with several U-wraps. The proposed FBS model was also applied to other comparable studies, and debonding strains were successfully predicted within an margin of error of 7%. Using the validated model, a parametric study of the FRP strengthened T-beam was conducted with various key parameters of the U-wrap, such as the angle of U-wrap and the number of U-wrap.
Lee Jaeha,Lee Jae-Seok,안기정 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.3
A taxonomic reappraisal of some species of Korean Oxyporus Fabricius is presented based on morphological and molecular characters (COI and 28S). A new species (O. parvus Lee and Ahn sp. nov.) and a new record (O. procerus Kraatz) are recognized in the Korean peninsula. The new species is superficially similar to O. germanus Sharp but can be separated by the structures of the median lobe of the aedeagus and molecular characters (partial COI and 28S). The minimum interspecific difference between O. parvus Lee and Ahn, sp. nov. and O. germanus (9.3–10.6%) was much higher than the maximum intraspecific difference between O. parvus Lee and Ahn, sp. nov. (2.1%) and they contained 7 and 4 molecular diagnostic characters, respectively. Three previous incorrect identifications are discussed and they (O. basicornis Cameron, O. basiventris Jarrige, and O. crocatus Fauvel) are excluded from the Korean fauna. The molecular analyses support the validity of the new species and the other five Korean species based on morphological characters. Descriptions with illustrations of habitus and diagnostic features of the new species and the new record are provided.
Characteristic Risk Factors Associated with Planned versus Impulsive Suicide Attempters
Jaeha Kim,Kang-Sook Lee,Dai Jin Kim,Seung-Chul Hong,Kyoung Ho Choi,Youngmin Oh,Sheng-Min Wang,Hae-Kook Lee,Yong-Sil Kweon,Chung Tai Lee,Kyoung-Uk Lee 대한정신약물학회 2015 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.13 No.3
Objective: The present study aimed to investigate predictors for planned suicide attempters. Methods: This study included 1,003 patients who attempted suicide and visited emergency department. They were divided into two groups, planned suicide attempters (SAs; n=133 [13.3%]) and impulsive SAs (n=870, [86.7%]), and the demographic variables, clinical characteristics, factors related to suicide, and psychiatric resources of the groups were compared. Results: Major depressive disorder and substance use disorders were more common among planned SAs than among impulsive SAs. Additionally, the planned SAs were older, more likely to be divorced, separated or widowed, and more likely to have co-morbid medical illnesses, severe depression, higher suicidality, and self-blaming tendencies than the impulsive SAs. Financial problems and physical illnesses were more common in planned SAs but interpersonal conflicts were more frequent in impulsive SAs. Planned SAs had fewer previous suicide attempts but these were more serious suicide attempts. The presence of the hope to die, a written will, and suicidal ideation of a repetitive, intense, and continuous nature were predictive of planned SAs. Conclusion: The present findings demonstrated that planned SAs had more severe psychopathology and medical illnesses than impulsive SAs. Therefore, screening for depression, substance use disorders, and suicidal plans among old and medically ill patients may be important for preventing suicide attempts.
고강도 콘크리트에 매입된 다월 철근의 구조 거동에 대한 실험적 분석
이재하 ( Lee Jaeha ),이성철 ( Lee Seong Cheol ),이경찬 ( Lee Kyoung Chan ),박상민 ( Park Sang Min ),정의석 ( Jeong Euiseok ) 한국구조물진단유지관리공학회 2017 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.21 No.1
In the sliding slab track of railway bridge, a lateral support block is used to control the lateral displacement. Therefore, it is important to analyze the behavior of dowel rebar and the lateral support block of the sliding slab track. In this study, high strength concrete and steel rebar was selected to analyze the behavior of dowel rebar and shear behavior of high strength dowel rebar and the lateral support block were compared to the equations developed by Soroushian et al. (1986) and CEB-FIP (2010).
( Jaeha Lee ),( Jinwoo Song ) 대한결핵 및 호흡기학회 2019 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.127 No.-
Background: Interstitial lung diseases (ILD) are chronic progressive lung disease with high morbidity and mortality. In recent studies, the prevalence of obstructive sleep apnea (OSA) in patients with ILD have been reported to be high. However, prevalence and predictive factors in Korean patients are not well defined. The aim of this study was to evaluate prevalence and predictive factors of OSA in Korean patients with ILD. Methods: Clinical data were retrospectively analyzed in 86 patients with ILD enrolled from December 2017 to April 2019 at Haeundae-Paik hospital. OSA was monitored with portable device (SOMNOcheck micro, level 4, Weinmann Medical Technology, Hamburg, Germany), and was defined by apnea-hypopnea index (AHI) above 5 per hour of sleep. Results: The median follow up period was 7 months. The mean age was 69.8 years and 64% were men. Among total ILD, idiopathic pulmonary fibrosis (IPF) was the most common (66.3%), followed by connective tissue disease (CTD) associated ILD (17.4%), and organizing pneumonia (5.8%), respectively. Forty six patients (53.5%) were diagnosed with OSA and IPF patients had more frequent OSA (64.9% vs. 31.0%, p = 0.003) than those with other ILD. Old age (OR 1.11, 95% CI 1.04-1.19, p = 0.002), high weight (OR 1.05, 95% CI 1.01-1.10, p = 0.012) and diabetes mellitus (OR 4.03, 95% CI 1.26-12.91, p = 0.019) were independent risk factors for OSA in multivariate logistic regression analysis. Survival was not different between ILD patients with and without OSA (14.1 months ± 29.3 vs. 12.1 ± 13.9 months, log-rank test, P = 0.819). Conclusions: The prevalence of OSA in Korean patients with ILD was high (53.5%), and was higher in IPF patients compared to those with other ILD. Old age, high weight and diabetes mellitus mean high risk of OSA in patient with ILD.
Lee, Jaeha,Ryou, YoungSeok,Cho, Sung June,Lee, Hyokyoung,Kim, Chang Hwan,Kim, Do Heui Elsevier 2018 Applied Catalysis B Vol.226 No.-
<P><B>Abstract</B></P> <P>We investigated the chemisorptive NO adsorption ability at a low temperature (120 °C) of the Pd/ZSM–5 passive NO<SUB>x</SUB> adsorbers (PNA) to address the cold-start NO<SUB>x</SUB> emission. The Pd/ZSM–5 showed a much higher NO adsorption ability after the oxidative treatment at 750 °C compared with the 500 °C treatment; according to the combined EXAFS, XPS and XRD results, atomically dispersed Pd species were formed over the former, while small PdO agglomerates were observed over the latter. The Pd species on the Pd/ZSM–5 were further examined by applying a NH<SUB>4</SUB>NO<SUB>3</SUB>-titration method, where an ion exchange occurred with only the ionic Pd in the zeolite. When the Pd(2)/ZSM–5 was treated at 750 °C, it exchanged ions with an NH<SUB>4</SUB>NO<SUB>3</SUB> solution whereby most of the Pd was ion-exchanged, and this resulted in a decreased NO adsorption capability. Alternatively, a much lesser amount of ion-exchanged Pd was found on the Pd/ZSM–5 that was treated at 500 °C. The combined results indicate that the ionic-Pd species on the ZSM–5, not the bulk PdO, are the active sites for the chemisorptive NO adsorption at the low temperature. The NO adsorption capability was also investigated as a function of the Pd loading and the Si-to-Al<SUB>2</SUB> molar ratio of the ZSM–5. The results suggest that an optimum Pd-to-Al molar ratio exists for the Pd/ZSM–5 with the maximum NO adsorption capability, which was found at around 0.25, thereby suggesting that the Al in the ZSM–5 framework led to the high dispersion of the ionic-Pd species up to the optimum Pd/Al ratio. Above the optimum Pd/Al ratio, however, the bulk-PdO phase formed on the ZSM–5 resulting in a lower NO adsorption capability; that is, the ZSM–5 with the higher Al content required a higher Pd amount for the attainment of the optimum NO adsorption capability. In summary, the chemisorptive NO adsorption at the low temperature is significantly influenced by both the Si-to-Al<SUB>2</SUB> molar ratio and the Pd-to-Al molar ratio of the Pd/ZSM–5 catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidative treatments at 750 °C activated the NO adsorption ability of Pd/ZSM-5. </LI> <LI> Isolated Pd species were formed in ZSM-5 after the oxidative treatment at 750 °C. </LI> <LI> Ionic Pd species turned out to be the active site for adsorbing NO. </LI> <LI> Optimum Pd to Al molar ratio for NO adsorption was found at 0.25. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>