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Experiments and computer simulation analysis of impact behaviors of micro-sized abrasive in waterjet cutting of thin multiple layered materials

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中国有色金属学会会刊：英文版 2012年第S3期22卷 864-869页

作者： jung-han lee Kang-Su PARK Myung Chang KANG Bo Sik KANG Bo Sung SHIN Engineering Research Center Pusan National University National Core Research Center Pusan National University Mechanical System Safety Research Division Korea Institute of Machinery and Materials

The abrasive waterjet (AWJ) is now widely used in the advanced cutting processes of polymers,metals,glass,ceramics and composite materials like thin multiple-layered material (TMM).Various research and development efforts have recently been made to understand the science of ***,the interaction mechanism between a workpiece and high-velocity abrasive particles still remains a complicated *** this work,the material removal mechanisms of AWJ such as micro penetration and micro dent were experimentally *** addition,a new computer simulation model considering high strain rate effect was proposed to understand the micro impact behavior of high-velocity micro-sized abrasives in AWJ cutting.

关键词： abrasive waterjet thin multiple layered materials micro-sized abrasive micro penetration micro dent

Rapid manufacturing of SiC molds with micro-sized holes using abrasive water jet

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中国有色金属学会会刊：英文版 2009年第B9期19卷 178-182页

作者： Bo-Sung SHIN Kang-Su PARK Yeon-Kyoung BAHK Sun-Ki PARK jung-han lee Jeung-Sang GO Myung-Chang KANG Chae-Moon lee ERC/NSDM Pusan National University School of Mechanical Engineering Pusan National University Microhole Company NCRC Pusan National University Samsung Electro-Mechanics

Silicon carbide (SiC) is highly wear resistant with good mechanical properties, including high temperature strength, excellent chemical resistance, and high thermal conductivity and thermal shock resistance. SiC molds, which can be produced with diverse microstructural features, are now widely used in glass molding owing to their excellent characteristics, and also have potential applicability in IT industries. SiC molds are traditionally fabricated by silicon micromachining or dicing. The fabrication cost of silicon micromachining is very high, however, because several expensive masks are needed. Furthermore, the fabrication time is very long. Meanwhile, it is difficult to make micro-patterned molds with arbitrary shapes using dicing saws. Abrasive water jet (AWJ) is widely applied to cut and drill very brittle, soft and fibrous materials. It offers high energy density, the absence of a heat affected zone(HAZ), high performance, and an environment friendly process. In spite of these advantages, micro-hole drilling via conventional AWJ processing suffers from notable shortcomings. We proposed a new abrasive supplying method of AWJ. The proposed method reduces frosting phenomena, and provides micro-machining of AWJ. The characteristics of a hole machined was investigated by the proposed AWJ process according to the ratio of water and abrasives. With the optimal experimental conditions, 3×3 array SiC molds with the diameter of 700 μm and depth of 900 μm were successfully manufactured.

关键词：快速模具制造磨料水射流碳化硅微型硅微加工型孔最佳实验条件机械性能

Controlled oxidation of Ni for stress-free hole transport layer of large-scale perovskite solar cells

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Nano Research 2019年第12期12卷 3089-3094页

作者： Seongha lee Hee-Suk Roh Gill Sang han jung-Kun lee Department of Mechanical Engineering and Materials Science University of PittsburghPennsylvania 15261USA School of Advanced Materials Science and Engineering Sungkyunkwan UniversitySuwon 16419Republic of Korea

The effect of the residual thermal stress of NiO films on the performance of an inverted type perovskite solar cell was *** this study,NiO films were grown on fluorine dopedtin oxide(FTO)substrates of different surface roughness by thermally oxidizing Ni film and weretested as a hole transport layer for large-scale perovskite solar *** and simulation results show that it is very important tosuppress the appearance of the residual stress at the NiO-FTO in terface during the oxidation of the Ni film for effective hole extracti *** Ni oxidation on the flat FTO film produced in-plane compressive stress in the NiO film due to the Ni film volume *** led to theformation of defects including small *** residual stress and defects in creased leakage curre nt through the NiO film,preve ntingholes from being selectively collected at the NiO-perovskite ***,when Ni was deposited and oxidized on the rough surface,the residual stress of the NiO film was negligible and its inhere nt high resistance was ***-free NiO film is an excelle nt holetransport layer that stops the photogenerated electrons of the perovskite layer from moving to *** improvements in the structural andelectrical qualities of the NiO film by engirteering the residual stress reduce the carrier recombination and increase the power conversi onefficiency of the perovskite solar cells to 16.37%.

关键词： nickel oxidation surface roughness residual stress perovskite solar cells large scale processing

Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments

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Nano Research 2017年第11期10卷 3885-3895页

作者： Jin Sun Yoo Gill Sang han Seongha lee Min Cheol Kim Mansoo Choi Hyun Suk jung jung-Kun lee School of Advanced Materials Science amp Engineering Sungkyunkwan University Suwon 440-746 Republic of Korea Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh Pennsylvania 15261 USA Department of Mechanical and Aerospace Engineering Seoul National University Seoul 08826 Republic of Korea

In spite of a continuous increase in their power conversion efficiency （PCE） and an economically viable fabrication process,organic-inorganic perovskite solar cells （PSCs） pose a significant problem when used in practical applications：They show fast degradation of the PCE when exposed to very humid *** this study,the stability of PSCs under very humid conditions is greatly enhanced by coating the surface of the PSC devices with a multi-layer film consisting of ultrahydrophobic and relatively hydrophilic layers.A hydrophobic composite of poly（methyl methacrylate）（PMMA）,polyurethane （PU）,and SiO2 nanoparticles successfully retards the water molecules from very humid ***,the hydrophilic layer with moderately PMMA captures the residual moisture within the perovskite layer;subsequently,the perovskite layer *** dual function of the coating film keeps the PCE of PSCs at 17.3% for 180 min when exposed to over 95% humidity.

关键词： perovskite solar cell stability surface coating ultrahydrophobic self-recovery

Efficient page layout analysis on small devices

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 800-804页

作者： Eun-jung han Chee-onn WONG Kee-chul jung Kyung-ho lee Eun-yi KIM Department of Naval Architecture and Ocean Engineering Inha University Human-Centered Interfaces Lab Department of Digital MediaSoongsil University Internet and Media Engineering Konkuk University

Previously we have designed and implemented new image browsing facilities to support effective offiine image contents on mobile devices with limited capabilities： low bandwidth, small display, and slow processing. In this letter, we fulfill the automatic production of cartoon contents fitting small-screen display, and introduce a clustering method useful for various types of cartoon images as a prerequisite stage for preserving semantic meaning. The usage of neural networks is to properly cut the various forms of pages. Texture information that is useful for grayscale image segmentation gives us a good clue for page layout analysis using the multilayer perceptron （MLP） based x-y recursive algorithm. We also automatically frame the segment MLP using agglomerative segmentation. Our experimental results show that the combined approaches yield good results of segmentation for several cartoons.

关键词： Efficient page layout analysis MLP-based segmentation Mobile devices Image segmentation Neural network

Next High Performance and Low Power Flash Memory Package Structure

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Journal of Computer Science & Technology 2007年第4期22卷 515-520页

作者： jung-Hoon lee ERI Control Instrumentation EngineeringGyeongSang National UniversityJinju660-701Korea

In general, NAND flash memory has advantages in low power consumption, storage capacity, and fast erase/write performance in contrast to NOR flash. But, main drawback of the NAND flash memory is the slow access time for random read operations. Therefore, we proposed the new NAND flash memory package for overcoming this major drawback. We present a high performance and low power NAND flash memory system with a dual cache memory. The proposed NAND flash package consists of two parts, i.e., an NAND flash memory module, and a dual cache module. The new NAND flash memory system can achieve dramatically higher performance and lower power consumption compared with any conventionM NAND-type flash memory module. Our results show that the proposed system can reduce about 78% of write operations into the flash memory cell and about 70% of read operations from the flash memory cell by using only additional 3KB cache space. This value represents high potential to achieve low power consumption and high performance gain.

关键词： flash memory NAND-type NOR-type memory localities buffer or cache memory

EXPERIMENTAL ESTIMATION OF A SCALING EXPONENT FOR TIP VORTEX CAVITATION VIA ITS INCEPTION TEST IN FULL-AND MODEL-SHIP

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Journal of Hydrodynamics 2012年第5期24卷 658-667页

作者： lee Jeung-Hoon jung Jae-Kwon lee Kyung-Jun han Jae-Moon PARK Hyung-Gil SEO Jong-Soo Samsung Ship Model Basin(SSMB) Marine Research InstituteSamsung Heavy IndustriesScience TownDaejeon 305-380Korea

Tip vortex cavitation noise of marine propeller became primary concems to reduce hazardous environmental impacts from commercial ship or to keep the underwater surveillance of naval ships. The investigations of the tip vortex and its induced noise are normally conducted through the model test in a water cavitation tunnel. However the Reynolds number of model-test is much smaller than that of the full-scale, which subsequently results in the difference of tip vortex cavitation inception. Hence, the scaling law between model- and full-scales needs to be identified prior to the prediction and assessment of propeller noise in full scale. From previous researches, it is generally known that the incipient caivtation number of tip vortex can be represented as a power of the Reynolds number. However, the power exponent for scaling, which is the main focus of this research, has not been clearly studied yet. This paper deals with the estimation of scaling exponent based on tip vortex cavitation inception test in both full- and model-scale ships. Acoustical measurements as well as several kind of signal processing technique for an inception criterion suggest the scaling exponent as 0.30. The scaling value proposed in this study shows slight difference to the one of most recent research. Besides, extrapolation of model-ship noise measurement using the proposed one predicts the full-scale noise measurement with an acceptable discrepancy.

关键词： tip vortex cavitation underwater radiated noise scaling exponent

Liquid-like adsorbent assembled by CNTs: Serving as renewable CO_(2) capture materials for indoor air

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Journal of Energy Chemistry 2021年第12期30卷 574-584,I0014页

作者： Jae Won lee Minjae Kim han Sol jung Ronghuan Xu Seonggon Kim Yong Tae Kang School of Mechanical Engineering Korea UniversitySeoul 02841South Korea

In this study,a CO_(2) capture material in the form of liquid-like adsorbents(LLAs) is developed to overcome the limitations of conventional types of *** increase in indoor activities necessitates the capture of CO_(2) in enclosed indoor *** spaces require safe and stable materials for CO_(2) capture because humans are present in these *** adsorbents are mainly used because liquid absorbents are unsuitable owing to noise and scattering *** LLA,the liquid absorbent assembled by carbon nanotubes(CNTs) is solidified and prevented from flowing and scattering *** present to maintain 95% of initial capacity after recycling 20 times,and have characteristics that can be regenerated in a low temperature heat source(80 to 120℃) and moisture *** work not only provides indoor useable CO_(2) capture materials,but also offers a new prospect in the field of adsorbents.

关键词： CO_(2)capture CNT Silicone oil Adsorbents Indoor air

Automatic salient object segmentation using saliency map and color segmentation

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Journal of Central South University 2013年第9期20卷 2407-2413页

作者： han Sung-ho jung Gye-dong lee Sangh-yuk HONG Yeong-pyo lee Sang-hun Department of Plasmabiodisplay Kwangwoon University Department of General Education Kwangwoon University Department of Electrical and Electronic Engineering Xi'an Jiaotong-Liverpool University Department of Hospital Management International University of Korea

A new method for automatic salient object segmentation is *** object segmentation is an important research area in the field of object recognition,image retrieval,image editing,scene reconstruction,and 2D/3D *** this work,salient object segmentation is performed using saliency map and color ***,color and intensity feature are extracted from mean shift segmentation(MSS)image,and saliency map is created using these *** average saliency per segment image is calculated using the color information from MSS image and generated saliency ***,second average saliency per segment image is calculated by applying same procedure for the first image to the thresholding,labeling,and hole-filling applied ***,labeling and hole-filling are applied to the mean image of the generated two images to get the final salient object *** effectiveness of proposed method is proved by showing 80%,89%and 80%of precision,recall and F-measure values from the generated salient object segmentation image and ground truth image.

关键词： salient object visual attention saliency map color segmentation