Band Dispersion in Lab-on-a chip for protein separation

Jaesool Shim,Prashanta Dutta,Cornelius F. Ivory 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10

Ampholyte based isoelectric focusing (IEF) simulation was conducted to study dispersion of proteins in a horse shoe microchannel. Four model proteins (pls= 6.49, 7.1, 7.93 and 8.6) are focused in a 1 ㎝ long horse shoe channel under an electric field of 300 V/㎝. The pH gradient is formed in the presence of 25 biprotic carrier ampholytes (?pK = 3.0) within a pH range of 6 to 9. The proteins are focused at 380 sec in a nominal electric field of 300 V/㎝. Our numerical results show that the band dispersions of a protein are large during the gradient formation stage, but the dispersions are significantly reduced when the double peaks start to merge. This rearrangement of spreading band isvery unique compared to linear electrokinetic phenomena (capillary zone electrophoresis) and is independent of channel position and channel shape. Hence, one can perform IEF and other self-sharpening electrokinetic methods, such as, isotachophoresis (ITP), in complex geometries without incorporating hyperturns.

Rapid detection for modified HLD to prognostic diagnosis

Jaesool Shim,Kyung-Hyun Cho,Wookju Jang,Gyungdong Lee 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4

Dispersion of protein bands in a horseshoe microchannel during IEF

Shim, Jaesool,Dutta, Prashanta,Ivory, Cornelius F. WILEY-VCH Verlag 2009 Electrophoresis Vol.30 No.5

<P>Ampholyte-based IEF is simulated for a 2-D horseshoe microchannel. The IEF model takes into account ionic-strength-dependent mobility corrections for both proteins and ampholytes. The Debye–Huckel–Henry model is employed to correct the protein mobilities and the Onsager–Debye–Huckel model is used to obtain effective mobilities of ampholytes from their limiting mobility. IEF simulations are conducted in the presence of 25 ampholytes (ΔpK=3.0) within a pH range of 6–9 under an electric field of 300 V/cm and using four proteins (pIs=6.49, 7.1, 7.93 and 8.6) focused in a 1-cm-long microchannel. The numerical results show that the concentrations of proteins and ampholytes are different when mobility corrections are considered but that the focusing positions remain the same regardless of mobility corrections. Our results also demonstrate that, unlike linear electrophoresis in which the bands deform significantly as they traverse a bend, during the transient portion of IEF racecourse dispersion is mitigated by focusing and, at focused-state, those bands that focus in the bend show no radial concentration dependence, i.e. they completely recover from racecourse dispersion, even within a tight turn.</P>

Biological Applications of Thiosemicarbazones and Their Metal Complexes

Shim, Jaesool,Jyothi, N. Rama,Farook, N.A. Mohammad Asian Journal of Chemistry 2013 Asian journal of chemistry Vol.25 No.10

Numerical and experimental study on biased tube temperature problem in tangential firing boiler

Akkinepally, Bhargav,Shim, Jaesool,Yoo, Kisoo Elsevier 2017 Applied thermal engineering Vol.126 No.-

<P><B>Abstract</B></P> <P>In this study, a numerical and experimental investigation on the flow field in a 500-MW unit of a tangentially fired boiler has been performed to understand the effect of residual swirl on the temperature distribution and inconsistency of flow velocity in the crossover pass. The k–k<SUB>L</SUB>–ω turbulence model was used in this study to analyse the possible formation of transition flow in the tangential firing boiler. Furthermore, 1D and 3D hybrid modelling were used for the simulation of the convective heat transfer in the boiler tube assembly. The commercially available code ANSYS Fluent and COMSOL were used for the studies, respectively. The numerical results for the velocity profile and residual swirl in the boiler were validated using the experimental results from the cold air velocity test, in which the flow velocity was directly measured in the full-scale boiler. The computational results agreed well with the experimental findings. Furthermore, from a comparison of the simulation and experiment, it was found that the biased gas flow induces non-uniform tube temperatures at the crossover pass area of the tangential firing boiler. These results aid in the detailed study of the residual swirl effects on the temperature or flue gas at various locations of the boiler. This study indicates that a non-uniform tube temperature at the crossover pass is an inherent problem resulting from residual swirl in the tangential firing boiler. Therefore, the pulverised coal burner should be fine-tuned to avoid tube rupture due to local overheating.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A full-scale CFD simulation was performed for a 500-MW unit of a tangentially fired boiler to determine the flow behaviour. </LI> <LI> The CFD model was validated with experimental results from the cold air velocity test. </LI> <LI> Temperatures of the boiler tube were measured directly in commercial tangential firing boilers. </LI> <LI> Biased temperature profile of the steam and tube is attributed to the non-uniform velocity of the flue gas. </LI> </UL> </P>

Rapid generation of spatially and temporally controllable long-range concentration gradients in a microfluidic device

Du, Yanan,Shim, Jaesool,Vidula, Mahesh,Hancock, Matthew J.,Lo, Edward,Chung, Bong Geun,T. Borenstein, Jeffrey,Khabiry, Masoud,M. Cropek, Donald,Khademhosseini, Ali Royal Society of Chemistry 2009 Lab on a chip Vol.9 No.6

<P>The ability to rapidly generate concentration gradients of diffusible molecules has important applications in many chemical and biological studies. Here we established spatially and temporally controllable concentration gradients of molecules (<I>i.e.</I> proteins or toxins) in a portable microfluidic device in an easy and rapid manner. The formation of the concentration gradients was initiated by a passive-pump-induced forward flow and further optimized during an evaporation-induced backward flow. The centimeter-long gradients along the microfluidic channel were shown to be spatially and temporally controlled by the backward flow. The gradient profile was stabilized by stopping the flow. Computational simulations of this dynamic process illustrated the combined effects of convection and diffusion on the gradient generation, and fit well with the experimental data. To demonstrate the applications of this methodology, a stabilized concentration gradient of a cardiac toxin, alpha-cypermethrin, along the microchannel was used to test the response of HL-1 cardiac cells in the micro-device, which correlated with toxicity data obtained from multi-well plates. The approach presented here may be useful for many biological and chemical processes that require rapid generation of long-range gradients in a portable microfluidic device.</P> <P>Graphic Abstract</P><P>Spatially and temporally controllable concentration gradients of molecules were established in a portable microfluidic device in an easy and rapid manner. The gradient formation was initiated by a passive-pump-induced forward flow and optimized during an evaporation-induced backward flow. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b815990d'> </P>

Artificial Intelligence assistive prediction of ionic conductivity in Li-based superionic conductors: A Molecular Dynamics Simulations validation

Bhargav Akkinepally,Jaesool Shim 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

The world is moving towards the renewables and Li-batteries play a vital role in that green future. Owing to the safety issues of liquid electrolytes, solid electrolytes are in demand to replace the already existing Li-ion battery infrastructure. This necessitates the research efforts into discovering suitable solid electrolytes which have higher ionic conductivities. As the process of screening of electrolytes by trial and error is time consuming and resource intensive, thereby demands the development of appropriate machine learning algorithms. In this work, we focus on developing a novel machine learning algorithm to predict the ionic conductivity of Li Super Ionic Conductors (LiSICON). The elemental features derived from the unit cell information and the atomic properties of the elements of 40 LiSICON compounds. The logistic regression model we developed is capable of classifying in which category the compound falls into from either good, average or bad with an accuracy of over 88 %. The test data results are validated with the molecular dynamics simulations. These findings exhibit the benefits of using such a tool in the preliminary screening of potential solid electrolytes with the existing data which helps in focusing only on the promising candidates thereby reducing the time consumption for experimentalists.

Opto-electrokinetic 효과에 의한 Toroidal Microvortex 형성에 관한 수치해석적 연구

김동(Dong Kim),심재술(Jaesool Shim),김경천(Kyung Chun Kim) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

In this study, the formation of a toroidal microvortex by optoelectrokinetic effect was numerically simulated using COMSOL v4.2a multiphysics software. AC voltage was applied to the two parallel electrodes in a microchannel to generate temperature gradient in the fluids. In addition to the AC electrothermal (ACET) effect, local heating by a laser illumination was also considered. Numerical simulations were conducted for dielectric fluids. The toroidal microvortex induced by the optoelectrokinetic effect shows that two counter-rotating vortices are produced above the bottom electrodes. Fluid motions in the middle of bottom boundary are cancelled out by flows in opposite directions and consequently producing stagnation. It is expected that micro/nano particles are deposited in bottom electrode. Local heating enhanced the intensity of microvortex substantially due to the additional temperature gradient, it was confirmed that the ACET effect with laser illumination can be used for rapid concentration of micro/nano particles in the spot area.

오목 정점을 이용한 셀 및 클러스터 구분과 계수

조미경(Migyung Cho),심재술(Jaesool Shim),김진석(Jinseok kim),문상준(Sangjun Moon) 한국정보과학회 2011 한국정보과학회 학술발표논문집 Vol.38 No.1C

셀 트래킹의 목적은 셀의 이동(translocation), 분할(mitosis), 통합(fusion), 아포토시스(apoptosis), 셀의 모양 변형, 셀들 간의 상호 작용 등을 포함하는 모든 셀의 행동들을 분석하기 위한 것이다. 셀은 시간이 경과함에 따라 새롭게 나타나기도, 죽기도 하며 한 개 이상의 셀이 부분적으로 겹쳐 클러스터를 형성하기도 하고 클러스터는 다시 여러 개의 셀로 분리되기도 한다. 본 연구에서는 현미경으로부터 얻은 이미지에서 셀 트래킹을 위한 이미지 처리 방법과 오목 정점을 이용하여 셀과 클러스터를 구분하여 계수하는 방법을 제시한다. 또한 타원 근사법(ellipse fitting)을 통해 클러스터를 몇 개의 셀로 분리하기 위한 방법을 제시하고 결과를 분석한다.

최소 극단치 분포를 이용한 자동차 도어 래치의 아이링 모델 가속 수명 예측을 위한 회귀 분석 방법 연구

손지훈(Jihoon Son),심재술(Jaesool Shim),배영화(Younghwa Bae),김우엽(Wooyoub Kim),김정재(Jungjae Kim),김청산(Chungsan Kim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11

Door latch of automobile is a necessary component for automobile passengers which performs not only Open/Close but also Lock/Unlock. Also, door latch is strongly controlled by automobile safety regulation and requires high reliability. Door latch is exposed to wide range of temperatures due to climate and repetitive load of motor is applied to gears. Therefore, estimation of cumulative failure rate and lifespan under stress condition is necessary. Therefore, in this study, the theoretical Erying model accelerated life anaylsis, which is the zero failure test method, is proposed using Weibull distribution theory under the log relationship between the Weibull distribution and Minimum extreme value distribution. This research investigated various parts inside of latch which is defined failure mechanisms and factors using step of reliability analysis. Also, HALT was performed for acceleration level decision. Failure mechanism of door latch is gear damage due to high/low temperature and repetitive load and applied temperature (-45℃ ~ 100℃) and load (18V, 24V) conditions to accelerate failure. Common shape parameter and scale parameters were derived as a result of multi-levels, factors ALT. By applying Eyring model, lifespan under specific temperature and load condition is estimated. Also, the theoretical and experimental values predicted by regression analysis using the minimum extreme value distribution under the log relationship with the weibull distribution were compared. As a result, it was confirmed that there was no error in the two values, and it was possible to theoretically predict the multifactor acceleration life.