Dual Function of Wnt Signaling during Neuronal Differentiation of Mouse Embryonic Stem Cells

Kim, Hanjun,Kim, Sewoon,Song, Yonghee,Kim, Wantae,Ying, Qi-Long,Jho, Eek-hoon Hindawi Publishing Corporation 2015 Stem cells international Vol.2015 No.-

<P>Activation of Wnt signaling enhances self-renewal of mouse embryonic and neural stem/progenitor cells. In contrast, undifferentiated ES cells show a very low level of endogenous Wnt signaling, and ectopic activation of Wnt signaling has been shown to block neuronal differentiation. Therefore, it remains unclear whether or not endogenous Wnt/<I>β</I>-catenin signaling is necessary for self-renewal or neuronal differentiation of ES cells. To investigate this, we examined the expression profiles of Wnt signaling components. Expression levels of Wnts known to induce <I>β</I>-catenin were very low in undifferentiated ES cells. Stable ES cell lines which can monitor endogenous activity of Wnt/<I>β</I>-catenin signaling suggest that Wnt signaling was very low in undifferentiated ES cells, whereas it increased during embryonic body formation or neuronal differentiation. Interestingly, application of small molecules which can positively (BIO, GSK3<I>β</I> inhibitor) or negatively (IWR-1-endo, Axin stabilizer) control Wnt/<I>β</I>-catenin signaling suggests that activation of that signaling at different time periods had differential effects on neuronal differentiation of 46C ES cells. Further, ChIP analysis suggested that <I>β</I>-catenin/TCF1 complex directly regulated the expression of <I>Sox1</I> during neuronal differentiation. Overall, our data suggest that Wnt/<I>β</I>-catenin signaling plays differential roles at different time points of neuronal differentiation.</P>

Functionalization of the Discontinuity Factor in the Albedo-Corrected Parameterized Equivalence Constants (APEC) Method

Kim, Woosong,Lee, Kyunghoon,Kim, Yonghee Informa UK (TaylorFrancis) 2018 Nuclear science and engineering Vol.192 No.1

Efficient Selection of Antibodies Reactive to Homologous Epitopes on Human and Mouse Hepatocyte Growth Factors by Next-Generation Sequencing-Based Analysis of the B Cell Repertoire

Kim, Soohyun,Lee, Hyunho,Noh, Jinsung,Lee, Yonghee,Han, Haejun,Yoo, Duck Kyun,Kim, Hyori,Kwon, Sunghoon,Chung, Junho MDPI 2019 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.20 No.2

<P>YYB-101 is a humanized rabbit anti-human hepatocyte growth factor (HGF)-neutralizing antibody currently in clinical trial. To test the effect of HGF neutralization with antibody on anti-cancer T cell immunity, we generated surrogate antibodies that are reactive to the mouse homologue of the epitope targeted by YYB-101. First, we immunized a chicken with human HGF and monitored changes in the B cell repertoire by next-generation sequencing (NGS). We then extracted the <I>V<SUB>H</SUB></I> gene repertoire from the NGS data, clustered it into components by sequence homology, and classified the components by the change in the number of unique <I>V<SUB>H</SUB></I> sequences and the frequencies of the <I>V<SUB>H</SUB></I> sequences within each component following immunization. Those changes should accompany the preferential proliferation and somatic hypermutation or gene conversion of B cells encoding HGF-reactive antibodies. One component showed significant increases in the number and frequencies of unique <I>V<SUB>H</SUB></I> sequences and harbored genes encoding antibodies that were reactive to human HGF and competitive with YYB-101 for HGF binding. Some of the antibodies also reacted to mouse HGF. The selected <I>V<SUB>H</SUB></I> sequences shared 98.3% identity and 98.9% amino acid similarity. It is therefore likely that the antibodies encoded by them all react to the epitope targeted by YYB-101.</P>

Neutronics feasibility of simple and dry recycling technologies for a self-sustainable breed-and-burn fast reactor

Kim, Chihyung,Hartanto, Donny,Kim, Yonghee Elsevier 2017 Annals of nuclear energy Vol.110 No.-

<P><B>Abstract</B></P> <P>This paper is concerned with the neutronics analysis of extremely simplified recycling technologies of spent fuels in a small breed-and-burn fast reactor (B&BR). The discharged fuels of the first generation B&BR, which achieved an average burnup of 160 GWd/MTHM, were used to construct a second generation B&BR core. Two types of high proliferation resistant recycling technologies, melt refining and the newly suggested super-simplified melt and treatment, were applied to process and treat the discharged fuels. Because the burnup profile of discharged fuels varies largely depending on its position in the core, the recycling of the discharged fuels was also carried out by grouping them into recycling regions including 1, 3, and 6 recycling regions. In this study, the core performance of the 2nd generation B&BR loaded with the recycled fuel, which was produced by different recycling technologies and recycling regions, was analyzed and compared. An optimum fuel loading scheme was also adopted to maximize the performance of the 2nd generation B&BR in terms of the burnup reactivity change, core lifetime, and power profiles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The preliminary study on self-sustainability of a B&BR fuel cycle was investigated. </LI> <LI> A proliferation-resistant and simple fuel recycling technology is used. </LI> <LI> The 2nd generation B&BR can be designed using the discharged fuel from the 1st B&BR. </LI> <LI> The importance of region-wise fuel recycling in nuclear fuel reprocessing has been confirmed. </LI> </UL> </P>

Comparison of Nonlinear Analysis and Equivalent Linear Analysis on 1D Site Response Analysis

( Yonghee Lee ),( Hak-sung Kim ),( Seok-chul Kim ),( Weon-hack Choi ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Equivalent linear and nonlinear analyses are the most common approaches to perform 1D site response analysis. Since these methods have inherent differences in analysis process (time domain, frequency domain), computed results yield different output. Equivalent linear analysis is a kind of linear analysis considering non-linearity and an approximation of hysteric soil behavior. Nonlinear analysis method is the hysteretic stress-strain response of soil and can represent more actual behavior rather than equivalent linear analysis. In this study 1D nonlinear analysis and equivalent linear analysis are performed with DEEPSOIL version 7.1 for 30 m soil depth. Shear modulus reduction and damping curve was used with Darendeli (2001) that has Ko is 0.5. Curve fitting for modulus reduction and damping function were performed with university of Illinois at Urbana-Champaign (MRDF-UIUC) model. Used soil model is pressure-dependent modified Kondner Zelasko (MKZ) and hysteretic unloading-reloading formulation follows non-masing rule in the nonlinear analyses. The thickness of each layer is 1 m. The used input motion is Northridge earthquake record (scaled from 0.05 g to 1 g). Analyses results show that ground behavior is very similar in the low peak ground acceleration (PGA) level but somewhat different in the high PGA level. In case of strong motion (i.e., PGA > 0.5 g) especially in the initial and decayed part, equivalent linear analyses results show under-prediction tendency but over-prediction tendency in the strong motion part. During strong motion part, soil stiffness decreased in the nonlinear analysis but is same in the equivalent linear analysis.

Activity gradient carbon felt electrodes for vanadium redox flow batteries

Kim, Youngkwon,Choi, Yun Young,Yun, Nari,Yang, Mingyu,Jeon, Yonghee,Kim, Ki Jae,Choi, Jung-Il Elsevier 2018 Journal of Power Sources Vol.408 No.-

<P><B>Abstract</B></P> <P>An activity gradient carbon felt (AGCF) electrode is prepared by a simple thermal oxidation method, which is composed of both a low activity electrode near the inlet side and a high activity electrode near the outlet side. The vanadium redox flow battery (VRFB) full cell with AGCF electrodes shows higher discharge capacity (18.7 Ah L<SUP>−1</SUP>) and coulomb efficiency (93.6%) than non-gradient carbon felt electrodes (14.3 Ah L<SUP>−1</SUP>, 88.4%) at a current density of 80 mA cm<SUP>−2</SUP>. From the computational analysis, the AGCF electrodes exhibit reduced overpotential results as well as improved uniform activity at low reactant concentration condition during charging and discharging at the current density. These results suggest that the AGCF electrode is an effective electrode design for high-performance VRFB featuring high energy density by improving electrolyte utilization as well as high roundtrip efficiency by improving energy efficiency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Activity gradient carbon felt was prepared by a thermal oxidation pre-treatment. </LI> <LI> AGCF enhanced electrolyte utilization at the current density of 80 mA cm<SUP>-2</SUP>. </LI> <LI> AGCF enhanced the uniformity of the reaction rates in the electrode. </LI> <LI> AGCF improved energy efficiency, yielding to a decrease of the overpotential. </LI> </UL> </P>

Improvement of CANDU safety parameters by using the CANFLEX fuel

Kim, Woosong,Motalab, Mohammad Abdul,Bae, Jun Ho,Kim, Yonghee Elsevier 2016 Annals of nuclear energy Vol.94 No.-

<P><B>Abstract</B></P> <P>In this study, the use of the CANFLEX fuel bundle in the CANDU6 reactor has been investigated with high-fidelity Monte Carlo simulations in view of major safety parameters. The CANFLEX fuel bundle is designed such that it has a smaller linear power and flatter bundle power distributions than those of the standard design. This results in a significantly lower average fuel temperature. In addition, with slightly larger coolant flow area than the standard design, the CANFLEX bundle is expected to improve fuel temperature coefficient (FTC) and coolant temperature coefficient (CTC) during normal operation. This study presents 2-D neutronic lattice evaluations of these safety parameters of the CANDU6 reactor loaded with CANFLEX fuel bundle against with the standard fuel design. To adequately model the equilibrium CANDU6 core, a number of different 2-D fuel bundle lattices were simulated on a huge number of neutron histories. For a reasonably accurate evaluation of the FTC, thermal motion of <SUP>238</SUP>U was considered with the Doppler Broadened Rejection Correction (DBRC) scheme. Based on these numerical evaluations, it can reasonably be concluded that the CANFLEX fuel design can possibly enhance safety of the CANDU6 reactor as its PCR is clearly negative for a wide range of reactor power. All depletion calculations were completed using the Monte Carlo Serpent2 code with ENDF/B-VII.0 library.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Average fuel temperature is significantly lower in the CANFLEX fuel bundle. </LI> <LI> CANFLEX provides ∼35% more negative FTC due to the lower fuel temperature. </LI> <LI> At hot full power condition, CTC is 53% lower with the CANFLEX fuel bundle. </LI> <LI> PCR of CANDU6 is noticeably improved with the CANFLEX fuel design. </LI> </UL> </P>

Measurement and Analysis for Determination of PCR of the CANDU6 Core

Kim, Jaeha,Motalab, Mohammad Abdul,Kim, Yonghee,Kim, Gwangsoo Informa UK (Taylor Francis) 2018 Nuclear technology Vol.201 No.2

A Study on Switching Intention of Broadcasting Service to MCN Service by Migration Theory

Yonghee Kim 한국유통과학회 2019 The Journal of Industrial Distribution & Business( Vol.10 No.1

Purpose - The Millennial Generation, which grew in the wake of the spread of the Internet and rapid changes in the media environment, is rapidly moving from the traditional broadcasting environment to the Internet-broadcasting environment in terms of content acceptance. With the emergence of UGC (User-generated content), the change in the status of single-person content creators enables the growth of multi-channel networks (MCN), a new content-distribution platform and an agency concept for single creators. Youtube-based MCN produces multiple single star producers and casts and provides its own video series through Youtube. It is also emerging as a major M&A target for global media providers in terms of providing content to a wide range of consumers with the same interests and consumption characteristics. In addition, for the Millennials generation, which are part of their lives, MCN is becoming the most suitable media for TGIF (Twitter, Google, i-phone, Facebook). Accordingly, this study defines newly emerging MCNs and analyzes the factors for accepting MCN-produced content based on the push-pull-mooring (PPM) model. Research design, data, and methodology - An empirical analysis is performed through a questionnaire survey. For this purpose, 204 people who have experience of watching MCN were studied. Collected data is processed through analysis of a structural equation model using R to test the hypothesis. Results - For the MCN service to become an alternative to existing media, it is necessary to continuously promote cultural diversity and diversity of attempts that conventional media cannot provide. It is the attractiveness of the alternative that has the greatest influence on the intention to switch to a MCN service. When we look at MCN content so far, certain patterns such as game progress, introduction, food, and chat rooms have already appeared. We need to overcome this and develop a completely new conceptual content that we have never seen before. This requires a more generous viewer perception of the topics covered. For diversity, linguistic and verbal violence should be tolerant in common sense to provide a foundation for securing cultural diversity. Conclusions - In this study, we tried to develop a comprehensive approach to the substitution effect of MCN. In terms of academic achievement, the PPM model is used to enhance the utilization of media and broadcasting. Practical implications are to provide an analytical framework for verifying alternative or complementary effects when viewers switch to MCN.

Improvement of Nodal Accuracy by Using Albedo-Corrected Parameterized Equivalence Constants

Kim, Woosong,Heo, Woong,Kim, Yonghee Academic Press 2017 Nuclear science and engineering Vol.188 No.3