• Title/Summary/Keyword: Cross­

Search Result 126, Processing Time 0.023 seconds

Efficient Synthesis of Nucleoside Phosphonates using Olefin Cross-Metathesis

  • Quan, Ling-Lin;Kim, Ai-Hong;Kooh, Dae-Ho;Ko, Ok-Hyun;Hong, Joon-Hee
    • Proceedings of the PSK Conference
    • /
    • 2003.10b
    • /
    • pp.173.3-173.3
    • /
    • 2003
  • In recent years, olefin cross-metathesis (CM) has emerged as a powerful and convenient synthetic technique in organic chemistry; however, as a general synthetic method, CM has been limited by the lack of predictability in product selectivity and stereoselectivity. A number of excellent studies have recently appeared in the literature which have shown that with the correct catalyst and reaction conditions CM can be used to access a variety of di-and trisubstituted olefinic products in moderate to high yield with good E/Z ratios. (omitted)

  • PDF

Dynamic analysis of bridge girders submitted to an eccentric moving load

  • Vieira, Ricardo F.;Lisi, Diego;Virtuoso, Francisco B.
    • Structural Engineering and Mechanics
    • /
    • v.52 no.1
    • /
    • pp.173-203
    • /
    • 2014
  • The cross-section warping due to the passage of high-speed trains can be a relevant issue to consider in the dynamic analysis of bridges due to (i) the usual layout of railway systems, resulting in eccentric moving loads; and (ii) the use of cross-sections prone to warping deformations. A thin-walled beam formulation for the dynamic analysis of bridges including the cross section warping is presented in this paper. Towards a numerical implementation of the beam formulation, a finite element with seven degrees of freedom is proposed. In order to easily consider the compatibility between elements, and since the coupling between flexural and torsional effects occurs in non-symmetric cross-sections due to dynamic effects, a single axis is considered for the element. The coupled flexural-torsional free vibration of thin-walled beams is analysed through the presented beam model, comparing the results with analytical solutions presented in the literature. The dynamic analysis due to an eccentric moving load, which results in a coupled flexural-torsional vibration, is considered in the literature by analytical solutions, being therefore of a limited applicability in practice engineering. In this paper, the dynamic response due to an eccentric moving load is obtained from the proposed finite element beam model that includes warping by a modal analysis.

Preparation of novel NF membrane via interfacial cross-linking polymerization

  • Lehi, Arash Yunessnia;Akbari, Ahmad;Soleimani, Hosna
    • Membrane and Water Treatment
    • /
    • v.6 no.3
    • /
    • pp.173-187
    • /
    • 2015
  • The goal of present work is the preparation of a novel positively charged nanofiltration (NF) membrane and its development for the cation removal of aqueous solutions. This NF membrane was fabricated by the surface modification of polysulfone (PSf) ultrafiltration support. The active top-layer was formed by interfacial cross-linking polymerization of poly(ethyleneimine) (PEI) with p-xylylene dichloride (XDC) and then quaternized with methyl iodide to form a perpetually positively charged layer. In order to improve the efficiency of nanofiltration membrane, the concentration of PEI, XDC and methyl iodide solutions, PEI coating and cross-linking time have been optimized. As a result, a high water flux and high $CaCl_2$ rejection (1,000 ppm) was obtained for the composite membrane with values of $18.29L/m^2.h$ and 93.62% at 4 bar and $25^{\circ}C$, respectively. The rejections of NF membrane for different salt solutions followed the order of $Na_2SO_4$ < $MgSO_4$ < NaCl < $CaCl_2$. Molecular weight of cut off (MWCO) was calculated via retaining of PEG solutions with different molecular weights that finally, it revealed the Stokes and hydrodynamic radius of 1.457 and 2.507 nm on the membrane selective layer, respectively. The most efficient positively charged nanofiltration membrane exhibited a $Ni^{2+}$ rejection of 96.26% for industrial wastewater from Shamse Hadaf Co. (Kashan, Iran).

An Observational Study on the Morphological Changes of the External Ear Canal by Converging DICOM Imaging and Design Modeling (DICOM 영상과 설계 모델링을 융합한 외이도의 형태적 변화 관찰 연구)

  • Kim, Hyeong-Gyun
    • Journal of the Korea Convergence Society
    • /
    • v.10 no.11
    • /
    • pp.173-179
    • /
    • 2019
  • DICOM(Digital Imaging and Communications in Medicine) imaging plays a significant role in the diagnosis and treatment of the human body, and design modeling is a technology of planning shapes in three dimensions according to the purpose. In this study, we converge these two technologies to observe the relationships of the cross-section, volume, and surface area to the morphological changes of the external ear canal. The experiment applied medical imaging technologies to acquire sections of the human body to create and divide centerlines using 3D shapes extracted from 19 external ear canals by applying stereolithography and 3-matic program. The results showed that the cross-sectional structure of the external ear canal had various shapes, such as oval (38.5%), semicircular (28.2%), mixed (17.9%), square (10.2%), and wrinkled (5.1%). In addition, the cross-sectional area of each phase increased as the length of the external ear canal increased, and the volume and surface area decreased towards the direction of the eardrum. However, the surface area reduction rate was relatively low. This indicates that the structure becomes irregular towards the direction of the eardrum.

A Large-scale Structural Mixing Model applied to Blowout of Turbulent Nonpremixed Jet Flames in a Cross air-flow

  • Lee, Kee-Man;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
    • /
    • 1997.06a
    • /
    • pp.163-173
    • /
    • 1997
  • This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.

  • PDF

Transdermal Delivery of Estradiol and Norethindrone Acetate: Effect of Vehicles and Pressure Sensitive Adhesive Matrix

  • Chun, Myung-Kwan;Choi, Hoo-Kyun
    • Journal of Pharmaceutical Investigation
    • /
    • v.35 no.3
    • /
    • pp.173-177
    • /
    • 2005
  • Addition of 30% propylene glycol was required to maintain sink condition in the evaluation of percutaneous absorption of estradiol and norethindrone acetate. The permeability of estradiol was higher in silicone and SIS adhesives. However, estradiol was crystallized in silicone, SIS, and SBS adhesive matrix. The permeability ratio of estradiol or norethindrone acetate from acrylic pressure sensitive adhesives varied widely depending on the functional group of the acrylic adhesives. PEO grafting to acrylic adhesive seemed to change physicochemical property of acrylic adhesive and increased the permeability of estradiol and norethindrone acetate significantly. On the contrary, highly cross-linked enhancer compatible acrylic adhesive decreased the permeability of both estradiol and norethindrone acetate. $Span^{\circledR}$ 20 provided the highest enhancing effect on the permeability of both estradiol and norethindrone acetate followed by oleic acid and $Crovol^{\circledR}$ EP40. The permeability of the drugs from the developed system was comparable to that from commercial $Combitran^{\circledR}$, although significantly lower amount of estradiol and norethindrone acetate were loaded in the developed system.

Object Detection from Mongolian Nomadic Environmental Images

  • Perenleilkhundev, Gantuya;Batdemberel, Mungunshagai;Battulga, Batnyam;Batsuuri, Suvdaa
    • Journal of Multimedia Information System
    • /
    • v.6 no.4
    • /
    • pp.173-178
    • /
    • 2019
  • Mongolian historical and cultural monuments on settlement areas of stone inscriptions, stone images, rock-drawings, remains of cities, architecture are still telling us their stories. These monuments depict the understanding of the word, philosophical and artistic outlook, beliefs, religion, national art, language, culture and traditions of Mongols [1]. Nowadays computer science, especially computer vision is applying in the other science fields. The main problem is how to apply and which algorithm can detect and classify the objects correctly. In this paper, we propose a method to detect object from Mongolian nomadic environment images. This work proposes a method for object detection that is the combination of the binary operations in the edge detection results. We found out the best method and parameters of state-of-the-art machine learning algorithms. In experimental result, we evaluate our results with 10-fold cross validation and split 66% strategies.

A Deep Learning Approach for Classification of Cloud Image Patches on Small Datasets

  • Phung, Van Hiep;Rhee, Eun Joo
    • Journal of information and communication convergence engineering
    • /
    • v.16 no.3
    • /
    • pp.173-178
    • /
    • 2018
  • Accurate classification of cloud images is a challenging task. Almost all the existing methods rely on hand-crafted feature extraction. Their limitation is low discriminative power. In the recent years, deep learning with convolution neural networks (CNNs), which can auto extract features, has achieved promising results in many computer vision and image understanding fields. However, deep learning approaches usually need large datasets. This paper proposes a deep learning approach for classification of cloud image patches on small datasets. First, we design a suitable deep learning model for small datasets using a CNN, and then we apply data augmentation and dropout regularization techniques to increase the generalization of the model. The experiments for the proposed approach were performed on SWIMCAT small dataset with k-fold cross-validation. The experimental results demonstrated perfect classification accuracy for most classes on every fold, and confirmed both the high accuracy and the robustness of the proposed model.

The Study of Logistics Process Standardization (물류 프로세스 표준화 연구)

  • Park, Sun Ho;Park, Soo Min
    • Journal of Korea Society of Digital Industry and Information Management
    • /
    • v.7 no.1
    • /
    • pp.173-183
    • /
    • 2011
  • Global logistics including Korea had developed at various fields through the developed IT technology. In addition, in changing into Internet based digital economy times, economic and logistics activities became extending into worldwide over the cross-border. Logistics activity performed by off-line rapidly changed in real environment. But, unfortunately business process modeling about the whole logistics was not happened, even though process modeling had done by transport stages or logistics entities. Therefore, it is difficult to grasp the whole logistics. Additional cost and time was requested due to no association between logistics entities and invisibility. So, this paper has to be process modeling for logistics industry domain. For objective modeling, work area shall be divided and it extracts general work process per each area. And then it defines subprocess of general work process. Cargo tracking in logistics industry domain means to grasp the status and present states at transportation or storage stage. This paper defines business process and data model for electronic processed work area using the UN/CEFACT standard modeling methodology.

EASYCLAVE SYSTEM을 이용한 imprint공법의 가능성

  • Gwak, Jeong-Bok;Lee, Sang-Mun;Jo, Jae-Chun;Lee, Hwan-Su
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2008.06a
    • /
    • pp.173-173
    • /
    • 2008
  • 이전 까진 기판용 imprinting공법 기술 개발 과제를 하면서 imprint공정 진행시 일축형프레스를 이용하여 실험을 하면서 전면적의 균일한 압력을 가하여 절연필름의 Residue film 적게 남는것이 가장 이상적이지만, stamp두께가 전면이 똑같은 두께가 아니고 편차가 있어서 imprint를 하고나면 stamp 편차가 두꺼운 쪽은 많은 압력이 가해지고, 적은 쪽은 압력전달이 적게되어 Demolding을 하고나면 기판위에 패턴은 고르게 전사되지만 Cross section을 보게 되면 한쪽은 Residue film이 많이 남고 다른 한쪽은 적게 남게 되어 디스미어 공법시 패턴에 손상이 가지 않게 완전한 Residue film 제어가 쉽지 않고, 여러장을 동시에 한판에 imprint가 불가능 하고 기판 size가 커지면 Residue film의 편차가 심해서 더 이상 공정 진행이 불가능 했다. 하지만 Easyclave장비로 imprint를 하면 공기의 압으로 stamp전면에 똑같은 압력이 가해져 Residue film의 편차가 거의 없이 공정 진행이 가능했으며, 두께가 서로 틀려도 여러장의 기판을 동시에 imprint를 할수 있게 되었다, 일축형 프레스와 Easyclave의 실험결과를 비교하여 Easyclave장비의 imprint가능성과 이로운점을 발표하고자 한다.

  • PDF