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Lee, Hyeok-Won,Park, Jung-Ho,Lee, Hee-Suk,Kim, Chun-Suk,Lee, Jin-Gyeom,Kim, Won-kyo,Ryu, Kyoung-Hwa,Ahn, Jung-Oh,Lee, Eun-Gyo,Kim, Seon-Won,Jeon, Jong-Min,Yang, Yung-Hun,Choi, Eui-Sung,Lee, Hong-Weon Society for Bioscience and Bioengineering, Japan 2019 Journal of bioscience and bioengineering Vol. No.
<P>Many volatile compounds, such as isoprene, a precursor used in the synthesis of natural rubber, have been produced through fermentation using genetically engineered microorganisms. Despite this biotechnological success, measuring the concentrations of volatile compounds during fermentation is difficult because of their high volatility. In current systems, off-line analytical methods usually lead to product loss, whereas on-line methods raise the production cost due to the requirement of complex devices. Here, we developed a novel on-line gas chromatography (GC)-based system for analyzing the concentration of isoprene with the aim to minimize the cost and requirement for devices as compared to current strategies. In this system, a programmable logic controller is used to combine conventional GC with a syringe pump module (SPM) directly connected to the exhaust pipe of the fermentor, and isoprene-containing samples are continuously pumped from the SPM into the GC using an air cylinder recycle stream. We showed that this novel system enables isoprene analysis during fermentation with convenient equipment and without the requirement of an expensive desorption tube. Furthermore, this system may be extended to the detection of other volatile organic compounds in fermentation or chemical processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This system analyzes the concentration of isoprene in aerobic fermentation. </LI> <LI> PLC is used to combine conventional GC with SPM directly connected to fermenter. </LI> <LI> Produced isoprene is continuously analyzed using the GC. </LI> <LI> This system may be extended to the detection of other volatile organic compounds. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Erosion Behavior of SiC Coated C/C Composites with Condition of Combustion Test
Hyeok-Jong Joo,Kyung-Dae Min,Jae-Won Lee 한국탄소학회 2003 Carbon Letters Vol.4 No.3
Carbon/carbon composites are ideal candidates for a number of aerospace applications including structural materials for advanced vehicles, leading edges, structures of re-entry and hypersonic vehicles and propulsion systems. One serious defect for such application of the carbon/carbon composites is their poor oxidation resistance in high temperature oxidizing environments. SiC coating was employed to protect the composites from oxidation. It is mechanically and chemically stable under extreme thermal and oxidative environments, provides good adhesion to the substrate, and offers good thermal shock resistance. The SiC layer on the nozzle machined from the carbon/carbon composites was formed by pack-cementation method. Then, erosion characteristic of SiC coated carbon/carbon nozzle was examined by combustion test using a liquid rocket motor. The erosion rates were measured as function of combustion pressure, ratio of oxygen to fuel, combustion time, density of the composites and geometry of reinforced carbon fibre in the composites. The morphology change of the composites after combustion test was investigated using SEM and erosion mechanism also was discussed.
Battery State-of-Charge Estimation Algorithm Using Dynamic Terminal Voltage Measurement
Lee, Su-Hyeok,Lee, Seong-Won The Institute of Electronics and Information Engin 2015 IEIE Transactions on Smart Processing & Computing Vol.4 No.2
When a battery is discharging, the battery's current and terminal voltage must both be measured to estimate its state of charge (SOC). If the SOC can be estimated by using only the current or voltage, hardware costs will decrease. This paper proposes an SOC estimation algorithm that needs to measure only the terminal voltage while a battery is discharging. The battery's SOC can be deduced from its open circuit voltage (OCV) through the relationship between SOC and OCV. But when the battery is discharging, it is not possible to measure the OCV due to the voltage drop in the battery's internal resistance (IRdrop). The proposed algorithm calculates OCV by estimating IRdrop using a dynamic terminal voltage measurement. This paper confirms the results of applying the algorithm in a hardware environment via algorithm binarization. To evaluate the algorithm, a Simulink battery model based on actual values was used.
A Study on Fatigue Damage Modeling Using Neural Networks
Lee Dong-Woo,Hong Soon-Hyeok,Cho Seok-Swoo,Joo Won-Sik The Korean Society of Mechanical Engineers 2005 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.19 No.7
Fatigue crack growth and life have been estimated based on established empirical equations. In this paper, an alternative method using artificial neural network (ANN) -based model developed to predict fatigue damages simultaneously. To learn and generalize the ANN, fatigue crack growth rate and life data were built up using in-plane bending fatigue test results. Single fracture mechanical parameter or nondestructive parameter can't predict fatigue damage accurately but multiple fracture mechanical parameters or nondestructive parameters can. Existing fatigue damage modeling used this merit but limited real-time damage monitoring. Therefore, this study shows fatigue damage model using backpropagation neural networks on the basis of X -ray half breadth ratio B / $B_o$, fractal dimension $D_f$ and fracture mechanical parameters can estimate fatigue crack growth rate da/ dN and cycle ratio N / $N_f$ at the same time within engineering limit error ($5\%$).
Lee, Yeom Pyo,Kim, Dae Won,Kang, Hye Won,Hwang, Jae Hyeok,Jeong, Hoon Jae,Sohn, Eun Jeong,Kim, Mi Jin,Ahn, Eun Hee,Shin, Min Jea,Kim, Duk‐,Soo,Kang, Tae‐,Cheon,Kwon, Oh‐,Shin,Cho, Su Blackwell Publishing Ltd 2012 The FEBS journal Vol.279 No.11
<P>Heat shock proteins (HSPs) are a highly conserved family of proteins that are induced in response to various environmental stressors including reactive oxygen species. HSP27 is a chaperone protein with the ability to increase cell survival in response to oxidative stress. Parkinson’s disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons. Although the mechanism of PD remains unclear, oxidative stress is known to be important in its pathogenesis. This study investigated the protective effects of PEP‐1‐HSP27 on neuronal damage induced by 1‐methyl‐4‐phenyl pyridinium (MPP<SUP>+</SUP>) in SH‐SY5Y cells and in a 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐induced PD mouse model. PEP‐1‐HSP27 rapidly entered the cells and protected them against MPP<SUP>+</SUP>‐induced toxicity by inhibiting the reactive oxygen species levels and DNA fragmentation. Furthermore, transduced PEP‐1‐HSP27 prevented dopaminergic neuronal cell death in the substantia nigra of MPTP‐induced PD mouse models. These results demonstrate that PEP‐1‐HSP27 provides a potential strategy for therapeutic delivery against various diseases and is a potential tool for the treatment of PD.</P>
Room-Temperature Compressive Transfer Printing of Nanowires for Nanoelectronic Devices
Lee, Won Seok,Choi, Jun-hyeok,Park, Inkyu,Lee, Jihye American Chemical Society 2012 Langmuir Vol.28 No.51
<P>Recently, there has been a growing interest in the controlled alignment and robust bonding process of nanowires (NWs) on nanoelectronic devices. In this paper, we developed an innovative process for the fabrication of NW-based devices by room-temperature and low-pressure compressive transfer printing of NWs, in which NWs could be simultaneously aligned and bonded onto the metal electrodes. In this process, chemically synthesized NWs were first transferred and aligned on an intermediate substrate by contact printing and then finally printed onto a target substrate with mechanically soft Au electrodes, which enables the embedding of aligned NWs under low-pressure (5 bar) and room-temperature condition. The resulting contact between NW and Au electrodes exhibits Schottky behavior and high mechanical bonding strength (>567 MPa). The electrical characteristics could be converted from Schottky to Ohmic contact through thermal annealing treatment at 250 °C for 5 min due to Cr diffusion and direct Cr-ZnO contact formation. The applications of the fabricated devices as ultraviolet (UV) and gas sensors were successfully demonstrated. Furthermore, NW-based electronic devices were fabricated on a flexible substrate by using this process and showed mechanical and electrical robustness under mechanical bending conditions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2012/langd5.2012.28.issue-51/la3036133/production/images/medium/la-2012-036133_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la3036133'>ACS Electronic Supporting Info</A></P>
Production of Bio-Based Isoprene by the Mevalonate Pathway Cassette in Ralstonia eutropha
( Hyeok-won Lee ),( Jung-ho Park ),( Hee-seok Lee ),( Wonho Choi ),( Sung-hwa Seo ),( Irika Devi Anggraini ),( Eui-sung Choi ),( Hong-weon Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.10
Isoprene has the potential to replace some petroleum-based chemicals and can be produced through biological systems using renewable carbon sources. Ralstonia eutropha can produce value-added compounds, including intracellular polyhydroxyalkanoate (PHA) through fatty acid and lipid metabolism. In the present study, we engineered strains of R. eutropha H16 and examined the strains for isoprene production. We optimized codons of all the genes involved in isoprene synthesis by the mevalonate pathway and manipulated the promoter regions using pLac and pJ5 elements. Our results showed that isoprene productivity was higher using the J5 promoter (1.9 ± 0.24 μg/l) than when using the lac promoter (1.5 ± 0.2 μg/l). Additionally, the use of three J5 promoters was more efficient (3.8 ± 0.18 μg/l) for isoprene production than a one-promoter system, and could be scaled up to a 5-L batch-cultivation from a T-flask culture. Although the isoprene yield obtained in our study was insufficient to meet industrial demands, our study, for the first time, shows that R. eutropha can be modified for efficient isoprene production and lays the foundation for further optimization of the fermentation process.