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Experimental and Computational Studies on Coanda Nozzle Flow for the Air Knife Application

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Journal of Thermal Science 2007年第2期16卷 164-169页

作者： Soon-Bum KWON Dong-Won lee Young-doo KWON School of Mechanical Engineering Kyungpook National University1370Sankyuk-dongDaegu 702-701Korea

To control the film thickness of zinc in the process of continuous hot-dip galvanizing, it is known from the early days that the gas wiping through an air knife is the most effective one. The gas wiping using in galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. So, in the present study, the effects of the deflection angle of Coanda nozzle on jet structure and the distribution of impinging pres- sure at the plate surface are investigated numerically and experimentally. In numerical analysis, the governing equations consisted of three-dimensional time dependent full Navier-Stokes equations, standard k-ε turbulence model to solve turbulent stTess and so on are employed. In experiment, 16 channel pressure scanning valve and 3-axis auto traversing unit are used to measure the impinging pressure at the strip surface. As a result, it is found that the smaller the deflection angle for the same nozzle slit of air knife is, the larger the impinging pressure is. To reduce the size of separation bubble and to enhance the cutting ability, it is recommendable to use an air knife with the Coanda nozzle.

关键词： Air knife Coanda effect edge splashing gas wiping hot-dip galvanizing impinging jet

Generation of Discrete Bicubic G^1 B-Spline Ship Hullform Surfaces from a Given Curve Notwork Using Virtual Iso-Parametric Curves

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Journal of Computer Science & Technology 2006年第2期21卷 265-271页

作者： Joong-Hyun Rhim doo-Yeoun Cho Kyu-Yeul lee Tao-Wan Kim EzGragh Co.Ltd.Seoul 135-080 Koren Department of Naval Architecture & Ocean Engincering Seoul National UniversitySeoul 151-744Korea Department of Naval Architecture & Ocean Engincering and Research Institute of Macine Systems Engineering Seoul National University Seoul 151-744Korea

We propose a method that automatically generates discrete bicubic G^1 continuous B-spline surfaces that interpolate the curve network of a ship ***,the curves in the network are classified into two types;boundary curves and ＂reference curves＂,The boundary curves correspond to a set of rectangular（or triangular）topological type that can be representes with tensot-product （or degenerate）B-spline surface ***,in the interior of the patches,surface fitting points and cross boundary derivatives are estimated from the reference curves by constructing ＂virtual＂isoparametric ***,a discrete G^1 continuous B-spline surface is gencrated by a surface fitting *** smooth ship hullform surfaces generated from curve networks corresponding to actual ship hullforms demonstrate the quality of the method.

关键词： curve netowork interpotation discrete G^1 continuous B-spline surface,iso-parametric curve,ship hullform

Fabrication of 3D Printed PCL/PEG Polyblend Scaffold Using Rapid Prototyping System for Bone Tissue Engineering Application

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Journal of Bionic Engineering 2018年第3期15卷 435-442页

作者： Su A Park Sang Jin lee Ji Min Seok Jun Hee lee Wan doo Kim Il Keun Kwon Department of Nature-Inspired Nanoconvergence Systems Korea Institute of Machinery and Materials 156 Gajeongbuk-ro Yuseong-gu Daejeon 34103 Republic of Korea Department of Dental Materials School of Dentistry Kyung Hee University 26 Kyungheedae-ro Dongdaemun-gu Seou102447 Republic of Korea

Three-dimensional （3D） printing is a novel process used to manufacture bone tissue engineered scaffolds. This process allows for easy control of the architecture at the micro structure. However, the scaffold properties are typically limited in terms of cellular activity at the scaffold surface due to the printed materials properties. In this study, we developed a polycaprolactone （PCL） blended with polyethylene glycol （PEG） 3D printed scaffold using a rapid prototyping system. The manufactured scaffolds were then washed out to form small pores on the surface in order to improve the scaffolds hydrophilicity. We analyzed the resultant material by using Scanning Electron Microscopy （SEM）, water absorption, water contact angle, in vitro WST-1, and the Bradford assay. Additionally, cells incubated on the fabricated scaffolds were visualized by Confocal Laser Scanning Microscopy （CLSM）. The developed scaffolds exhibited small pores on the strand surface which served to increase hydrophilicity as well as improve cellular proliferation and increase total protein content. Our findings suggest that the presence of small pores on the scaffolds can be used as an effective tool for improving implant cellular interaction. This research indicates that these modified scaffolds can be considered useful for bone tissue engineering applications to improve human health.

关键词： polycaprolactone polyethylene glycol polyblend 3D printing porosity bone tissue engineering

A Study of the Gas Flow through Air Jet Loom

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Journal of Thermal Science 2007年第2期16卷 159-163页

作者： Heuy-Dong Kim Chae-Min Lim Ho-Joon lee doo-Hwan Chun School of Mechanical Engineering Andong National University388Songcheon-dongAndong 760-749KoreaE-mail:kimhd Korea Textile Machinery Research Institute 300Sampoong-dongKyeongsan 712-210Korea

Air jet loom, as one of the shuttleless looms, transports a yam into warps using viscosity and kinetic energy of an air jet. Performance of this picking system depends on the ability of instantaneous inhalation/exhaust, configuration of nozzle, operation characteristics of a check valve, etc. In the recent past, many studies have been reported on the air jet discharged from a nozzle exit, but studies for understanding the flow field characteristics associated with shear layer and shock wave/boundary layer interaction in the nozzle were not conducted enough. In this paper, a computational study was performed to explain the flow field in the air jet nozzle with an acceleration tube and validated with previous experimental data available. The results obtained from the computational study show that, in the supersonic flow regime, the flow field depends significantly on the length of acceleration tube. As nozzle pressure ratio increases, drag force acting on the string also increases. For a longer acceleration tube, the total pressure loss is large, owing to the frictional loss.

关键词： compressible flow nozzle shear layer shock wave air jet loom shuttleless loom

GIGANTEA Shapes the Photoperiodic Rhythms of Thermomorphogenic Growth in Arabidopsis

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Molecular Plant 2020年第3期13卷 459-470页

作者： Young-Joon Park Jae Young Kim June-Hee lee Byoung-doo lee Nam-Chon Paek Chung-Mo Park Department of Chemistry Seoul National UniversitySeoul 08826Korea Department of Plant Science Seoul National UniversitySeoul 08826Korea Plant Genomics and Breeding Institute Seoul National UniversitySeoul 08826Korea These authors contributed equally to this article

Plants maintain their internal temperature under environments with fluctuating temperatures by adjusting their morphology and architecture,an adaptive process termed ***,the rhythmic patterns of plant thermomorphogenesis are governed by day-length ***,it remains elusive how thermomorphogenic rhythms are regulated by ***,we show that warm temperatures enhance the accumulation of the chaperone GIGANTEA(Gl),which thermostabilizes the DELLA protein,REPRESSOR OF ga1-3(RGA),under long days,thereby attenuating PHYTOCHROME INTERACTING FACTOR 4(PIF4)-mediated *** contrast,under short days,when Gl accumulation is reduced,RGA is readily degraded through the gibberellic acid-mediated ubiquitination-proteasome pathway,promoting thermomorphogenic *** data indicate that the GI-RGA-PIF4 signaling module enables plant thermomorphogenic responses to occur in a day-length-dependent *** propose that the Gl-mediated integration of photoperiodic and temperature information shapes thermomorphogenic rhythms,which enable plants to adapt to diel fluctuations in day length and temperature during seasonal transitions.

关键词： thermomorphogenesis day length Gl RGA PIF4

Performance of a New Ion Source for KSTAR Tokamak Plasma Heating

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Plasma Science and Technology 2014年第6期16卷 620-624页

作者： Tae-Seong KIM Seung Ho JEONG doo Hee CHANG Kwang Won lee Sang-Ryul IN Korea Atomic Energy Research Institute

In the experimental campaign of 2010 and 2011 on KSTAR, the NBI-1 system was equipped with one prototype ion source and operated successfully, providing a neutral beam power of 0.7-1.6 MW to the tokamak plasma. The new ion source planned for the 2012 KSTAR campaign had a much more advanced performance compared with the previous one. The target performance of the new ion source was to provide a neutral deuterium beam of 2 MW to the tokamak plasma. The ion source was newly designed, fabricated, and assembled in 2011. The new ion source was then conditioned up to 64 A/100 keV over a 2-hour beam extraction and performance tested at the NB test stand （NBTS） at the Korea Atomic Energy Research Institute （KAERI） in 2012. The measured optimum perveance at which the beam divergence is a minimum was about 2.5μP, and the minimum beam divergent angle was under 1.0° at 60 keV. These results indicate that the 2.0 MW neutral beam power at 100 keV required for the heating of plasma in KSTAR can be delivered by the installation of the new ion source in the KSTAR NBI-1 system.

关键词： NBI ion source KSTAR neutral beam plasma heating positive based ion

Estimation of effective plant area index for South Korean forests using LiDAR system

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Science China(Life Sciences) 2010年第7期53卷 898-908页

作者： KWAK doo-Ahn lee Woo-Kyun KAFATOS Menas SON Yowhan CHO Hyun-Kook lee Seung-Ho Department of Environmental Science and Ecological Engineering Korea University Center of Excellence in Earth Observing Schmid College of ScienceChapman University Division of Forest Resources Information Korea Forest Research Institute

Light Detection and Ranging(LiDAR) systems can be used to estimate both vertical and horizontal forest *** components,the leaves of trees and the understory can be described with high precision,using geo-registered *** on this concept,the Effective Plant Area Indices(PAIe) for areas of Korean Pine(Pinus koraiensis),Japanese Larch(Larix leptolepis) and Oak(Quercus spp.) were estimated by calculating the ratio of intercepted and incident LIDAR laser rays for the canopies of the three forest ***,the canopy gap fraction(GLiDAR) was generated by extracting the LiDAR data reflected from the canopy surface,or inner canopy area,using k-means *** LiDAR-derived PAIe was then estimated by using GLIDAR with the Beer-Lambert law.A comparison of the LiDAR-derived and field-derived PAIe revealed the coefficients of determination for Korean Pine,Japanese Larch and Oak to be 0.82,0.64 and 0.59,*** differences between field-based and LIDAR-based PAIe for the different forest types were attributed to the amount of leaves and branches in the forest *** absence of leaves,in the case of both Larch and Oak,meant that the LiDAR pulses were only reflected from *** probability that the LiDAR pulses are reflected from bare branches is low as compared to the reflection from branches with a high leaf *** is because the size of the branch is smaller than the resolution across and along the 1 meter LIDAR laser ***,a better predictive accuracy would be expected for the model if the study would be repeated in late spring when the shoots and leaves of the deciduous trees begin to appear.

关键词： leaf area index plant area index LiDAR k-means clustering gap fraction beer-lambert law

Broadband omnidirectional light detection in flexible and hierarchical ZnO/Si heterojunction photodiodes

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Nano Research 2017年第1期10卷 22-36页

作者： Seongdong Lim doo-Seung Um Minjeong Ha Qianpeng Zhang Youngsu lee Yuanjing Lin Zhiyong Fan Hyunhyub Ko School of Energy and Chemical Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan Metropolitan City 44919 Republic of Korea Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China

The development of flexible photodetectors has received great attention for future optoelectronic applications including flexible image sensors, biomedical imaging, and smart, wearable systems. Previously omnidirectional photodetectors were only achievable by integration of a hemispherical microlens assembly on multiple photodetectors. Herein, a hierarchical photodiode design of ZnO nanowires （NWs） on honeycomb-structured Si （H-Si） membranes is demonstrated to exhibit excellent omnidirectional light-absorption ability and thus maintain high photocurrents over broad spectral ranges （365 to 1,100 nm） for wide incident angles （0° to 70°）, which enabled broadband omnidirectional light detection in flexible photodetectors. Furthermore, the stress-relieving honeycomb pattern within the photodiode micromembranes provided photodetectors with excellent mechanical flexibility （10% decrease in photocurrent at a bending radius of 3 mm） and durability （minimal change in photocurrent over 10,000 bending cycles）. When employed in semiconductor thin films, the hierarchical NW/honeycomb heterostructure design acts as an efficient platform for various optoelectronic devices requiring mechanical flexibility and broadband omnidirectional light detection.

关键词： flexible photodetector photodiode omnidirectional hierarchicalzinc oxide nanowire

Potentiating activity of rhein in targeting of resistance genes in methicillin-resistant Staphylococcus aureus

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Asian Pacific Journal of Tropical Medicine 2019年第1期12卷 14-18页

作者： Ryong Gong Dae Young lee Jae Won lee doo Jin Choi Geum-Soog Kim Sang Hyuk lee Young-Seob lee Department of Herbal Crop Research National Institute of Horticultural & Herbal Science Rural Development Administration

Objective: To investigate the synergistic effect between rhein(RHE) and oxacillin against Staphylococcus aureus(MRSA) at the gene level. Method: A minimum inhibitory concentration and checkerboard dilution test were conducted to evaluate antibacterial activity. Reverse transcriptase polymerase chain reaction was conducted to investigate the gene expressions. Results: RHE exhibited a minimum inhibitory concentration of 62.5-250.0 μg/mL against various MRSA strains and the reference strain, respectively. As revealed by the checkerboard assay, a combination of RHE and oxacillin exhibited synergistic or partially synergistic effects against MRSA strains. RHE decreased the expressions of mecA/blaZ in a dose-dependent manner. RHE also decreased the expressions of the regulator genes mecI/blaI and mecR1/blaR1. Conclusions: We suggest that RHE affects the activity of mecR1/blaR1, which is located in the cell membrane of MRSA and results in the suppression of mecA/mecI/mecR1 and blaZ/blaI/blaR1 gene expressions.

关键词： Antimicrobials Mechanism of action Staphylococcus aureus Polymerase chain reaction