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Zinc(II), palladium(II) and cadmium(II) complexes containing 4-methoxy-N-(pyridin-2-ylmethylene)aniline derivatives: Synthesis, characterisation and methyl methacrylate polymerization
No full textA series of Zn(II), Pd(II) and Cd(II) complexes, [(L)nMX2]m (L = L-a – L-c; M = Zn, Pd, X = Cl; M = Cd, X = Br; n, m = 1 or 2), containing 4-methoxy-N-(pyridin-2-ylmethylene)aniline (L-a), 4-methoxy-N-(pyridin-2-ylmethyl)aniline (L-b) and 4-methoxy-N-methyl-N-(pyridin-2-ylmethyl)aniline (L-c) have been synthesized and characterized. The X-ray crystal structures of Pd(II) complexes [L1PdCl2] (L = L-b and L-c) revealed distorted square planar geometries obtained via coordinative interaction of the nitrogen atoms of pyridine and amine moieties and two chloro ligands. The geometry around Zn(II) centre in [(L-a)ZnCl2] and [(L-c)ZnCl2] can be best described as distorted tetrahedral, whereas [(L-b)2ZnCl2] and [(L-b)2CdBr2] achieved 6-coordinated octahedral geometries around Zn and Cd centres through 2-equivalent ligands, respectively. In addition, a dimeric [(L-c)Cd(μ–Br)Br]2 complex exhibited typical 5-coordinated trigonal bipyramidal geometry around Cd centre. The polymerization of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) was evaluated by all the synthesized complexes at 60 °C. Among these complexes, [(L-b)PdCl2] showed the highest catalytic activity (3.80 × 104 g PMMA/mol·Pd·h) yielding high molecular weight (9.12 × 105 g/mol) poly(methyl methacrylate) (PMMA). Syndio-enriched PMMA (characterized using 1H NMR spectroscopy) of ca. 0.68 was obtained with Tg in the range 120 – 128 °C. Unlike imine and amine moieties, the introduction of N-methyl moiety has an adverse effect on the catalytic activity, but the syndiotacticity remained unaffected
High-Resolution Simulation of Snowfall over the Korean Eastern Coastal Region Using WRF Model:Sensitivity to Domain Nesting-Down Strategy
No full textThe eastern coastal area of the Korean Peninsula, Yeongdong region, often experiences severe snowfall during the winter season. We studied the development mechanism of a snowfall case occurred in February 2014 using the Weather Research and Forecasting (WRF) model at the convection-permitting resolution of 1 km. The model reasonably captured the observed snowfall, and three factors were discovered as important contributors to this snowfall case: a temperature contrast between land and ocean, a high-pressure system over the northeastern part of the Korean Peninsula, and the mountainous terrain. Cold and dry air blown from the high-pressure system gains heat and moisture when it passes over the East Sea enhancing the low-level instability. When the air mass reaches the coastline, updraft is generated by the density difference with the continental atmosphere and by the mountain slope. Further sensitivity experiments were conducted by adjusting strategies of nesting down (offline and online). Sensitivity experiments consist of three offline nesting experiments with different boundary condition update frequencies in 6, 3 and 1 h and one online nesting experiment that updates the boundary condition every integration time step. The major snowfall along the mountain range located in the middle of domain does not change significantly regardless of the nesting frequency. The offline nesting causes unphysical discontinuities of precipitation along the north and east sides of lateral boundary where wind blows in, which are caused by the absence of condensed hydrometeor variables in the lateral boundary condition. The domain nesting strategy tested in this study has dramatically impacted on the upper troposphere structure in the model: artificial fluctuations at the upper troposphere in the offline nesting simulations were significantly alleviated in the online nesting simulation
IoT 환경에서의 시공간 조인의 효율적 처리 기법
No full text시공간 조인은 서로 다른 릴레이션의 데이터 중 서로 동일한 시간과 동일한 위치 값을 가지는 데이터를 결합하는 연산이다. 특히 최근 IoT의 보급과 함께 서로 다른 사물들이 과거에 발생시킨 데이터 중 동일한 시간에 동일한 위치에서 발생된 데이터를 검색하기 위해 시공간 조인의 필요성이 증가하고 있다. 본 논문에서는 둘 이상의 사물들이 발생시킨 데이터를 효율적으로 시공간 조인하는 기법을 제안한다. 제안 방법은 평면과 시간으로 이루어진 3차원 시공간을 작은 부분 공간들로 나누고, 각 부분 공간 별로 그 내부에 데이터가 존재하는 사물들을 기록한다. 사물들 간 시공간 조인이 요청되면, 제안 방법은 해당 사물들의 데이터가 서로 가까이 존재하는 공간들을 탐색한다. 그 후 탐색된 공간 내에 존재하는 데이터만을 가져와서 조인을 수행한다. 따라서 제안 방법은 서로 조인 가능성이 있는 데이터만을 접근하므로 수행비용이 크게 감소한다. 실제 사물 데이터로 성능을 측정한 결과 제안 방법은 기존 시공간 조인 방법에 비해 수행 시간을 크게 단축함을 확인하였다
웹 통합인증을 위한 SAML과 OIDC 규약 간 토큰변환 시스템의 개발
No full text연합인증은 다수의 보안도메인에서 웹 통합인증을 가능케 하는 표준화된 사용자 인증 및 인가체계이다. 국제표준 보안규약인 SAML(Security Assertion Markup Language)를 이용하며 호환성 있는 기술 프로파일을 사용함으로써 비밀번호 피로도의 해소, 개인정보 보호의 강화, 연구자원의 공동 활용 가능성 증대와 같은 효과를 기대할 수 있다. 하지만 SAML 인증규약은 기술구현이 어렵고 구동환경의 설정과 메타데이터의 관리가 쉽지 않은 문제점을 가지고 있다. 다수의 국가에서 토큰의 구조가 간단하고 메타정보의 관리가 용이한 OIDC(OpenID Connect)를 차세대 연합인증 규약으로 수용하려는 움직임을 보이고 있다. 본 논문은 웹 응용이 연합인증을 목적으로 SAML 인증규약과 OIDC 인증규약을 모두 사용할 수 있는 토큰변환 시스템을 제안하고 필요성과 세부적인 구현 내용을 소개한다. 또한, 데이터과학 플랫폼인 JupyterHub와 OIDC를 이용해 연동하고 웹 통합인증의 처리과정을 살펴봄으로써 개발한 시스템의 성능과 기능을 정성적으로 분석한다
대졸 청년층의 이직의도에 영향을 미치는 주요 요인: 정규직 여부에 따른 비교 및 분석
No full text최근 높은 청년 실업률이 심각한 문제지만, 어렵게 취업에 성공한 대졸 청년층의 잦은 이직이나 조기 퇴사도 점점 중요한 이슈가 되고 있다. 이에 따라 본 연구에서는 ‘밀레니얼 세대’로 불리는 대졸 청년층의 이직의도에 영향을 미치는 주요 요인에 대해 분석하였으며, 추가적으로 정규직 여부에 따른 비교 및 분석을 수행하였다.
실증분석을 위해 본 연구는 한국고용정보원에서 실시한 2017년 대졸자직업이동경로조사(2016 GOMS) 데이터를 사용하였다. 분석 결과, 개인의 발전 가능성, 적성(흥미) 일치도, 일의 기술 수준이 높을수록 이직을 준비할 가능성이 낮게 나타났지만, 전공 일치도는 이직의도에 유의한 영향을 미치지 않았다. 그리고 정규직 여부는 개인의 발전 가능성과 이직의도 간의 부(-)의 관계를 강화시켰다.
본 연구에서는 대졸 청년층의 가치관을 파악하기 위해 외재적 가치보다 내재적 가치를 중심으로 이직의도를 분석하였다는 점에서 그 의의가 있으며, 정규직과 비정규직 근로자 간의 차이도 확인할 수 있었다
Weekly ILI patient ratio change prediction using news articles with support vector machine
No full textBackground: Influenza continues to pose a serious threat to human health worldwide. For this reason, detecting influenza infection patterns is critical. However, as the epidemic spread of influenza occurs sporadically and rapidly, it is not easy to estimate the future variance of influenza virus infection. Furthermore, accumulating influenza related data is not easy, because the type of data that is associated with influenza is very limited. For these reasons, identifying useful data and building a prediction model with these data are necessary steps toward predicting if the number of patients will increase or decrease. On the Internet, numerous press releases are published every day that reflect currently pending issues.
Results: In this research, we collected Internet articles related to infectious diseases from the Centre for Health Protection (CHP), which is maintained the by Hong Kong Department of Health, to see if news text data could be used to predict the spread of influenza. In total, 7769 articles related to infectious diseases published from 2004 January to 2018 January were collected. We evaluated the predictive ability of article text data from the period of 2013–2018 for each of the weekly time horizons. The support vector machine (SVM) model was used for prediction in order to examine the use of information embedded in the web articles and detect the pattern of influenza spread variance. The prediction result using news text data with SVM exhibited a mean accuracy of 86.7 % on predicting whether weekly ILI patient ratio would increase or decrease, and a root mean square error of 0.611 on estimating the weekly ILI patient ratio.
Conclusions: In order to remedy the problems of conventional data, using news articles can be a suitable choice, because they can help estimate if ILI patient ratio will increase or decrease as well as how many patients will be affected, as shown in the result of research. Thus, advancements in research on using news articles for influenza prediction should continue to be pursed, as the result showed acceptable performance as compared to existing influenza prediction researches
Quantitative Characterization of Protein−Lipid Interactions by Free Energy Simulation between Binary Bilayers
No full textUsing a recently developed binary bilayer system (BBS) consisting of two patches of laterally contacting bilayers, umbrella sampling molecular dynamics (MD) simulations were performed for quantitative characterization of protein-lipid interactions. The BBS is composed of 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) with an embedded model membrane protein, a gramicidin A (gA) channel. The calculated free energy difference for the transfer of a gA channel from DLPC (hydrophobic thickness ≈ 21.5 Å) to DMPC (hydrophobic thickness ≈ 25.5 Å) bilayers, ΔG(DLPC → DMPC), is −2.2 ± 0.7 kcal/mol. This value appears at odds with the traditional view that the hydrophobic length of the gA channel is ∼22 Å. To understand this discrepancy, we first note that recent MD simulations by different groups have shown that lipid bilayer thickness profiles in the vicinity of a gA channel differ qualitatively from the deformation profile predicted from continuum elastic bilayer models. Our MD simulations at low and high gA:lipid molar ratios and different membrane compositions indicate that the gA channel’s effective hydrophobic length is ∼26 Å. Using this effective hydrophobic length, ΔG(DLPC → DMPC) determined here is in excellent agreement with predictions based on continuum elastic models (−3.0 to −2.2 kcal/mol) where the bilayer deformation energy is approximated as a harmonic function of the mismatch between the channel’s effective hydrophobic length and the hydrophobic thickness of the bilayer. The free energy profile for gA in the BBS includes a barrier at the interface between the two bilayers which can be attributed to the line tension at the interface between two bilayers with different hydrophobic thicknesses. This observation implies that translation of a peptide between two different regions of a cell membrane (such as between the liquid ordered and disordered phases) may include effects of a barrier at the interface in addition to the relative free energies of the species far from the interface. The BBS allows for direct transfer free energy calculations between bilayers without a need of a reference medium, such as bulk water, and thus provides an efficient simulation protocol for the quantitative characterization of protein-lipid interactions at all-atom resolution
