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Development of a peristaltic Micropump for Bio-Medical Applications Based on Mini LIpCA

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Journal of Bionic Engineering 2008年第2期5卷 135-141页

作者： Thanh Tung Nguyen My pham Nam seo Goo Department of Aerospace Engineering Konkuk University Department of Advanced Technology Fusion Konkuk University

This paper presents the design, fabrication, and experimental characterization of a peristaltic micropump. The micropump is composed of two layers fabricated from polydimethylsiloxane （pDMS） material. The first layer has a rectangular channel and two valve seals. Three rectangular mini lightweight piezo-composite actuators are integrated in the second layer, and used as actuation parts. Two layers are bonded, and covered by two polymethyl Methacrylate （pMMA） plates, which help increase the stiffness of the micropump. A maximum flow rate of 900μ*** 1 and a maximum backpressure of 1.8 kpa are recorded when water is used as pump liquid. We measured the power consumption of the micropump. The micropump is found to be a promising candidate for bio-medical application due to its bio-compatibility, portability, bidirectionality, and simple effective design.

关键词： peristaltic micropump LIpCA pDMS bio-medical applications

Effect of internal sloshing on added resistance of ship

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Journal of Hydrodynamics 2017年第1期29卷 13-26页

作者： Min-Guk seo Yonghwan kim Dong-Min park korea Research Institute of Ships and Ocean Engineering DaejeonKorea Department of Naval Architecture and Ocean Engineering Seoul National UniversitySeoulKorea

The motion responses of ships carrying liquid cargo are affected not only by external wave excitation, but also by internal sloshing-induced forces and moments. Sloshing flow is coupled with the ship motion. This means the added resistance in waves may change when sloshing occurs inside the tank of the ship. In this study, the motion responses and added resistance of a ship, coupled with the sloshing-induced internal forces and moments are considered by using the linear potential theory. The three-dimensional Rankine panel method, in which the physical quantities are represented by using B-spline basis function, is applied. The sloshing flow of inner tanks is also simulated by Using the Rankine panel method and linearized boundary value problem. To study the added resistance, a near-field method, which integrates the second-order pressure on a body surface, is applied. The model ship is a blunt modified Wigley model with two inner tanks. Numerical results obtained without inner tanks are compared with the experimental data, and then the effect of filling ratio of inner tanks on ship motion and added resistance are observed. The components that induce added resistance are examined, and the effects of surge motion on sloshing flow and added resistance are briefly considered. This study shows that the sloshing flow inside the inner tanks may significantly influence not only the motion responses, but also added resistance, especially, when the incident wave frequency approaches the resonance frequency of the sloshing flow.

关键词： Added resistance sloshing seakeeping coupled effect Rankine panel method

Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

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Friction 2023年第7期11卷 1292-1306页

作者： kuk-Jin seo Hyun-Joon kIM Dae-Eun kIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of precision Mechanical Engineering Kyungpook National UniversitySangju 37224Republic of Korea Department of Advanced Science and Technology Convergence Kyungpook National UniversitySangju 37224Republic of Korea

This work shows that a soft,thin film comprising randomly aligned carbon nanotubes(CNTs)can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh *** investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film,multi-walled CNTs(MWCNTs)and diamond-like carbon(DLC)thin films were prepared to conduct nanoscale tribological experiments using the atomic force microscopy(AFM).The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal *** demonstrate the wear reduction mechanism of the MWCNT thin film,its indentation and frictional behaviors were *** indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin *** permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load *** results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures.

关键词： carbon nanotube(CNT) thin film wear friction elastic recovery

Effect of friction on the contact stress of a coated polymer gear

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Friction 2020年第6期8卷 1169-1177页

作者： Su-Min BAE kuk-Jin seo Dae-Eun kIM Department of Mechanical Engineering Yonsei UniversitySeoul 03722Republic of Korea

polymer gears are used extensively in various ***,durability issues have been emerging because of friction at gear tooth contact *** extend the lifetime of polymer gears,a low-frictional coating has been considered as a possible *** this study,a finite element simulation method was performed to investigate the contact stress between a pair of coated polymer *** simulation included various friction coefficients(COFs)for studying the effects of friction during the *** results revealed that the friction causes the contact stress to shift over the roll angle,which is attributed to the direction of the sliding friction based on a free-body *** also investigated the effects of coating and found that a thin coating has little effect on the bulk deformation behavior of the ***,the stress distribution in the coating at the pitch point was investigated as the COF *** zero friction,three notable stress regions were observed:1)the center of the surface,2)the end of the contact,and 3)the overall contact *** COF was increased in the micro-slip region of the contact interface,both tensile and compressive stresses in the coating *** study provides significant aid to engineers for understanding the stress response of the coating applied to polymer gears to achieve an optimal design.

关键词： coating contact stress finite element method(FEM) friction polymer gear

Two-dimensional perovskite SrNbO_(2) N with Zr doping for accelerating photoelectrochemical water splitting

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Journal of Materials Science & Technology 2023年第11期142卷 176-184页

作者： Thanh Tam Thi Tran Van-Huy Trinh Jeongsuk seo Department of Chemistry College of Natural SciencesChonnam National University77 Yongbong-roBuk-guGwangju 61186South Korea

The superior ability of perovskite-type SrNbO_(2) N to absorb intensive visible light makes it a potential semiconductor to produce hydrogen and oxygen by photoelectrochemical(pEC)water splitting under *** surface morphologies,such as shape and structure,of the oxynitride strongly affect its photoactivity,although the mechanism has been hardly ***,we report a two-dimensional(2D)porous SrNbO_(2) N plate with Zr doping,nitrided from layered perovskite Sr_(5)Nb_(4)O_(15) and also its largely enhanced pEC water splitting ***^(4+)was doped in Sr_(5)Nb_(4)O_(15) during flux-assisted calcination using kCl,producing 2D-type truncated-octahedral Sr_(5)Nb_(4)O_(15):Zr plates approximately 50 nm in *** nitridation completely transformed Sr_(5)Nb_(4)O_(15):Zr to 2D single-crystalline SrNbO_(2) N:Zr with a large surface area,which was subsequently used to fabricate a thin and uniform photoanode by the spin coating *** a result,the Co(OH)_(x)/SrNbO_(2) N:Zr/FTO photoanode capable of absorbing visible light of up to 680 nm exhibited an activity of 2.0 mA cm^(-2) at 1.23 V vs the reversible hydrogen electrode for water splitting under AM 1.5G simulated *** improvement in photoactivity mainly originated from the 2D surface morphology of SrNbO_(2) N:Zr,which is clearly distinguishable from 3D-type *** to electrochemical analyses,the 2D structure of SrNbO_(2) N:Zr boosted the separation and accelerated the transfer of charges photogenerated during the water splitting,thus driving the reaction ***,the result empirically demonstrates that controlling the surface morphology of SrNbO_(2) N is an effective strategy to suppress the recombination of charges and minimize their diffusion pathway,eventually enhancing the pEC activity.

关键词： Solar water splitting Water oxidation BaNbO_(2)N Doping engineering Flux-assisted calcination Spin coating

Magnetic field regression using artificial neural networks for cold atom experiments

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Chinese physics B 2024年第2期33卷 46-51页

作者：陈子霆黃建陶 Bojeong seo 黄明琛 Mithilesh k.parit 何逸飞甄浩廷 Jensen Li Gyu-Boong Jo Department of physics The Hong Kong University of Science and TechnologyKowloon 999077China

Accurately measuring magnetic fields is essential for magnetic-field sensitive experiments in areas like atomic,molecular,and optical physics,condensed matter experiments,and other ***,since many experiments are often conducted in an isolated environment that is inaccessible to experimentalists,it can be challenging to accurately determine the magnetic field at the target ***,we propose an efficient method for detecting magnetic fields with the assistance of an artificial neural network(NN).Instead of measuring the magnetic field directly at the desired location,we detect fields at several surrounding positions,and a trained NN can accurately predict the magnetic field at the target *** training,we achieve a below 0.3%relative prediction error of magnetic field magnitude at the center of the vacuum chamber,and successfully apply this method to our erbium quantum gas apparatus for accurate calibration of magnetic field and long-term monitoring of environmental stray magnetic *** demonstrated approach significantly simplifies the process of determining magnetic fields in isolated environments and can be applied to various research fields across a wide range of magnetic field magnitudes.

关键词： ultracold gases trapped gases measurement methods and instrumentation

Significant control of metal-insulator transition temperature through catalytic excessive oxygen doping in high-performance vanadium dioxide nanobeam channel

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Journal of Materials Science & Technology 2020年第9期44卷 96-101页

作者： Minhwan ko Sang Yeon Lee Jucheol park Hyungtak seo Department of Energy Systems Research Ajou UniversitySuwon16499Republic of Korea Gyeongbuk Science Technology promotion Center Gumi Electronics&Information Technology Research InstituteGumi39717Republic of Korea Department of Materials Science and Engineering Ajou UniversitySuwon16499Republic of Korea

The strategy of a reliable transition temperature control of vanadium dioxide(VO2)is *** VO2 nanobeams were synthesized by a thermal chemical vapor deposition(TCVD)*** metal-insulator transition(MIT)temperature increases to above 380k when the TiO2 ratio of the source is 5 at.%,although the Ti source is not physically doped into VO2 *** XpS spectra of the V 2p orbital reveal the excessive oxidation of V after the TCVD processes with a higher TiO2 ratio,indicating that the TiO2 precursor is important in the O-doping of the surface V O bonds when forming volatile Ti-O gas ***,TiO2 reactants can be used as a VO2 surface chemical modifier to manipulate the MIT transition temperature and maintain a homogenous VO2 phase,which is useful for a Mott device application with a record on/off switching ratio>104 and Mott transition temperature>380 k.

关键词： VO2 Mott transition Metal-insulator transition temperature Oxygen doping Titanium catalyst

Unusual neural tract between injured fornix and pedunculopontine nucleus in a patient with traumatic brain injury

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Neural Regeneration Research 2017年第9期12卷 1559-1560页

作者： Sung Ho Jang Jeong pyo seo Department of physical Medicine and Rehabilitation College of Medicine Yeungnam University

It has been known that four cholinergic nuclei are located in the septal region and basal forebrain （Ch 1： medial septal nucleus, Ch 2： vertical nucleus of the diagonal band, Ch 3： horizontal limb of the diagonal band and Ch 4： nucleus basalis of Meynert） and two are located in the brainstem （Ch 5： pedunculopontine nucleus and Ch 6： laterodorsal tegmental nucleus）（Selden et al., 1998; Lucas-Meunier et al., 2003; Mesulam, 2004; Nieuwenhuys et al., 2007）. The fornix transfers information on episodic mem- ory between the medial diencephalon and the medial temporal lobe （Afifi and Bergman, 2005; Wolk and Budson, 2010）. The fornix is known to obtain cholinergic innervation from Ch 1 and Ch 2, and to project to the hippocampal formation （Selden et al., 1998; Lucas-Meunier et al., 2003; Mesulam, 2004; Nieu- wenhuys et al., 2007; Dere et al., 2008; Naidich and Duvernoy, 2009; Isaacson and pribram, 2013）.

关键词： TBI Unusual neural tract between injured fornix and pedunculopontine nucleus in a patient with traumatic brain injury

portable and Efficient Implementation of CRYSTALS-kyber Based on WebAssembly

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Computer Systems Science & Engineering 2023年第8期46卷 2091-2107页

作者： seog Chung seo Heeseok kim Department of Financial Information Security Kookmin UniversitySeoul02707Korea Department of Cyber Security College of Science and TechnologyKorea UniversitySejong30019Korea

With the rapid development of quantum computers capable of realizing Shor’s algorithm,existing public key-based algorithms face a significant security ***-kyber has been selected as the only key encapsulation mechanism(kEM)algorithm in the National Institute of Standards and Technology(NIST)post-Quantum Cryptography(pQC)*** this study,we present a portable and efficient implementation of a Crystals-kyber post-quantum kEM based on WebAssembly(Wasm),a recently released portable execution framework for high-performance web *** now,most kyber implementations have been developed with native programming languages such as C and *** there are a few previous kyber implementations based on JavaScript for portability,their performance is significantly lower than that of implementations based on native programming ***,it is necessary to develop a portable and efficient kyber implementation to secure web applications in the quantum computing *** kyber software is based on JavaScript and Wasm to provide portability and efficiency while ensuring quantum ***,the overall software is written in JavaScript,and the performance core parts(secure hash algorithm-3-based operations and polynomial multiplication)are written in ***,we parallelize the number theoretic transform(NTT)-based polynomial multiplication using single instruction multiple data(SIMD)functionality,which is available in *** three steps in the NTT-based polynomial multiplication have been parallelized with Wasm SIMD intrinsic *** software outperforms the latest reference implementation of kyber developed in JavaScript by×4.02(resp.×4.32 and×4.1),×3.42(resp.×3.52 and×3.44),and×3.41(resp.×3.44 and×3.38)in terms of key generation,encapsulation,and decapsulation on Google Chrome(***,and Microsoft Edge).As far as we know,this is the first software implementation of kyber with Wasm technology in the web enviro

关键词： Crystals-kyber post-quantum cryptosystem(pQC) javascript WebAssembly SIMD web application internet of things(IoT) edge computing