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1.5kW급 PEMFC용 연료처리장치 내 수성가스치환반응기 시동시간 단축을 위한 수치해석
김근수(Keunsoo Kim),김선영(Sunyoung Kim),강인용(Inyong Kang),지현진(Hyunjin Ji),김영철(Youngchul Kim),배중면(Joongmyeon Bae) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
A Proton Exchange Membrane Fuel Cell (PEMFC) system is spotlighted as a military power source, which has many benefits such as mobility, efficiency and quietness. PEMFC requires pure hydrogen as a fuel and on-board reforming is a realistic way to supply hydrogen. For that purpose fuel processor was developed, but is difficult to apply in real applications due to its relatively long start-up time. Two step Water Gas Shift(WGS) reactors consisting of high and low temperature reactors (HTS and LTS, respectively) mostly delay start-up time. The objective of present study is to develop and apply computational models and to design start-up protocol of WGS reactors. Transient temperature analysis was performed in each reactor with various boundary conditions. The start-up time highly depends on the wall condition and heat supply rate to WGS reactors. The start-up time is decreased with high heat supply rate. The temperature of the HTS reaches to the target very fast with the isothermal wall conditions, but the adiabatic wall condition is better for heating LTS. The optimized start-up protocol is suggested considering the results.
연료분무 및 연소 1 : 희박 직접분사 LPG 엔진의 운전영역에 따른 배기특성
김근수 ( Keunsoo Kim ),최대현 ( Daehyun Choi ),김정환 ( Junghwan Kim ),오승묵 ( Seungmook Oh ),김창업 ( Changup Kim ) 한국액체미립화학회 2015 한국액체미립화학회 학술강연회 논문집 Vol.2015 No.-
The lean-burn direct injection engine can help improve the fuel economy and reduce harmful engine-out emissions in spark-ignition engines. The use of Liquefied Petroleum Gas (LPG) in lean-burn engines has the advantages of being a premixed mixture and decreasing carbonized emission due to its lower carbon contents. In the present study, the emission characteristics of lean-burn direct injection LPG engine at whole operation range were investigated. The torque of the engine was varied from idle to full load for the speed range of 1000rpm-3000rpm. Stoichiometric operation was adopted under idle and high-load condition and lean-burn operation was applied to 40~80Nm operation because of throttle limitation. The selection of optimal injection and spark timing were based on the fuel consumption and combustion stability. The engine test results indicate that simultaneous improvement of fuel consumption and reduction of the NOx emission were realized under the lean-burn regime. However, the Soot emission and carbon based emissions were partially increased under 40Nm condition due to application of Inter-injection Spark Ignition (ISI) strategy.
김근수 ( Keunsoo Kim ),오승묵 ( Seungmook Oh ),김정환 ( Junghwan Kim ),김창업 ( Changup Kim ),이용규 ( Yonggyu Lee ) 한국액체미립화학회 2016 한국액체미립화학회 학술강연회 논문집 Vol.2016 No.-
The ultra-lean combustion is considered to improve fuel economy and reduce harmful exhaust emissions in direct injection spark ignition engine. However, due to its high level of soot emission in lean-burn direct injection combustion, the use of Liquefied Petroleum Gas (LPG) has potential to reduce carbon related emissions and become easily stratified mixture because of its simple structure and its higher vapor pressure respectively. Therefore, the effects of the injection strategies on the combustion and emission characteristics including particle emission of the ultra-lean combustion with LPG were investigated in a prototypal 2,000 cm<sup>3</sup> and 4-cylinder engine. Four injection schemes (L-SI, L-ISI, E-IIS and L-IIS) were utilized to implement the lean-burn LPG combustion under the most frequently used passenger car engine operating point. According to the study, the fully stratified injection strategies indicate about 18% improvement in thermal efficiency; but, the combustion fluctuation was observed due to stratification. Both the NOx and CO emissions were reduced simultaneously compared to homogeneous stoichiometric combustion, but increasing the particulate matter emission was observed.
Keunsoo Won,Sun-Mi Kim,Sae-A Lee,Byung-Yong Rhim,Seong-Kug Eo,Koanhoi Kim 대한생리학회-대한약리학회 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.6
TLR6 forms a heterodimer with TLR2 and TLR4. While proinflammatory roles of TLR2 and TLR4 are well documented, the role of TLR6 in inflammation is poorly understood. In order to understand mechanisms of action of TLR6 in inflammatory responses, we investigated the effects of FSL-1, the TLR6 ligand, on expression of chemokine CCL2 and cytokine IL-1Ղ and determined cellular factors involved in FSL-1-mediated expression of CCL2 and IL-1Ղ in mononuclear cells. Exposure of human monocytic leukemia THP-1 cells to FSL-1 resulted not only in enhanced secretion of CCL2 and IL-1Ղ, but also profound induction of their gene transcripts. Expression of CCL2 was abrogated by treatment with OxPAPC, a TLR-2/4 inhibitor, while treatment with OxPAPC resulted in partially inhibited expression of IL-1Ղ. Treatment with FSL-1 resulted in enhanced phosphorylation of Akt and mitogen- activated protein kinases and activation of protein kinase C. Treatment with pharmacological inhibitors, including SB202190, SP6001250, U0126, Akt inhibitor IV, LY294002, GF109203X, and RO318220 resulted in significantly attenuated FSL-1-mediated upregulation of CCL2 and IL-1Ղ. Our results indicate that activation of TLR6 will trigger inflammatory responses by upregulating expression of CCL2 and IL-1Ղ via TLR-2/4, protein kinase C, PI3K-Akt, and mitogen-activated protein kinases.
Kim, Keunsoo,Jeong, Jihoon,Azad, Abul K.,Jin, Sang Beom,Kim, Jung Hyun Elsevier 2016 APPLIED SURFACE SCIENCE - Vol.365 No.-
<P><B>Abstract</B></P> <P>Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> (Ln=La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB>; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB>, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> (NSTM) and Sm<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> (SSTM). In various respects, NSTM and SSTM will be desirable reforming catalysts and anode candidates for high temperature solid oxide fuel cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Chemical states of Ln<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> (Ln: La, Nd and Sm) were analyzed. </LI> <LI> Charge compensation occurred with the reduction of Mn and Ti. </LI> <LI> The Nd substitution effect allowed some Ti to convert into a metallic behavioral component. </LI> <LI> NSTM and SSTM had a large amount of lattice oxygen; however, LSTM retained a large quantity of adsorbed oxygen. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Measured Ti 2p peaks and deconvolution peaks of Nd<SUB>0.5</SUB>Sr<SUB>0.5</SUB>Ti<SUB>0.5</SUB>Mn<SUB>0.5</SUB>O<SUB>3±d</SUB> under oxidizing condition (left) and NSTM under reducing condition (right).</P>
QKI, a miR‐200 target gene, suppresses epithelial‐to‐mesenchymal transition and tumor growth
Kim, Eun Ju,Kim, Jeong Seon,Lee, Sieun,Lee, Heejin,Yoon, Jung‐,Sook,Hong, Ji Hyung,Chun, Sang Hoon,Sun, Der Sheng,Won, Hye Sung,Hong, Soon Auck,Kang, Keunsoo,Jo, Jeong Yeon,Choi, Minyoung,Shin, John Wiley Sons, Inc. 2019 International journal of cancer: Journal internati Vol.145 No.6
<P>The microRNA‐200 (miR‐200) family plays a major role in specifying epithelial phenotype by preventing expression of the transcription repressors ZEB1 and ZEB2, which are well‐known regulators of the epithelial‐to‐mesenchymal transition (EMT) in epithelial tumors including oral squamous cell carcinoma (OSCC). Here, we elucidated whether miR‐200 family members control RNA‐binding protein quaking (QKI), a newly identified tumor suppressor that is regulated during EMT. We predicted that miR‐200a and miR‐200b could recognize <I>QKI</I> 3′‐UTR by analyzing TargetScan and The Cancer Genome Atlas head and neck squamous cell carcinoma (HNSCC) dataset. Forced expression of miR‐200b/a/429 inhibited expression of ZEB1/2 and decreased cell migration in OSCC cell lines CAL27 and HSC3. QKI expression was also suppressed by miR‐200 overexpression, and the 3′‐UTR of <I>QKI</I> mRNA was directly targeted by miR‐200 in luciferase reporter assays. Interestingly, shRNA‐mediated knockdown of <I>QKI</I> led to pronounced EMT and protumor effects in both <I>in vitro</I> and <I>in vivo</I> studies of OSCC. Furthermore, high expression of QKI protein is associated with favorable prognosis in surgically resected HNSCC and lung adenocarcinoma. In conclusion, QKI increases during EMT and is targeted by miR‐200; while, it suppresses EMT and tumorigenesis. We suggest that QKI and miR‐200 form a negative feedback loop to maintain homeostatic responses to EMT‐inducing signals.</P>
Kim Hyung Seok,Na Min Jeong,Son Keun Hong,Yang Hee Doo,Kim Sang Yean,Shin Eunbi,Ha Jin Woong,Jeon Soyoung,Kang Keunsoo,Moon Kiho,Park Won Sang,Nam Suk Woo 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-
Aberrant adenosine-to-inosine (A-to-I) RNA editing, catalyzed by adenosine deaminase acting on double-stranded RNA (ADAR), has been implicated in various cancers, but the mechanisms by which microRNA (miRNA) editing contributes to cancer development are largely unknown. Our multistage hepatocellular carcinogenesis transcriptome data analyses, together with publicly available data, indicated that ADAR1 was the most profoundly dysregulated gene among RNA-editing enzyme family members in liver cancer. Targeted inactivation of ADAR1 inhibited the in vitro tumorigenesis of liver cancer cells. An integrative computational analyses of RNA-edited hotspots and the known editing frequency of miRNAs suggested that the miRNA miR-3144-3p was edited by ADAR1 during liver cancer progression. Specifically, ADAR1 promoted A-to-I editing of canonical miR-3144-3p to replace the adenosine at Position 3 in the seed region with a guanine (ED_miR-3144-3p(3_A < G)) in liver cancer cells. We then demonstrated that Musashi RNA-binding protein 2 (MSI2) was a specific target of miR-3144-3p and that MSI2 overexpression was due to excessive ADAR1-dependent over-editing of canonical miR-3144-3p in liver cancer. In addition, target prediction analyses and validation experiments identified solute carrier family 38 member 4 (SLC38A4) as a specific gene target of ED_miR-3144-3p(3_A < G). The ectopic expression of both ADAR1 and the ED_miR-3144-3p(3_A < G) mimic enhanced mitotic activities, and ADAR1 suppressed SLC38A4 expression in liver cancer cells. Treatments with mouse-specific ADAR1-, MSI2-siRNA-, or SLC38A4-expressing plasmids suppressed tumorigenesis and tumor growth in a mouse model of spontaneous liver cancer. Our findings suggest that the aberrant regulation of ADAR1 augments oncogenic MSI2 effects by excessively editing canonical miR-3144-3p and that the resultant ED_miR-3144-3p(3_A < G) simultaneously suppresses tumor suppressor SLC38A4 expression, contributing to hepatocellular carcinogenesis.