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Analysis on thermal stress deformation of rotary air-preheater in a thermal power plant
Hongyue Wang,Lingling Zhao,Zhigao Xu,Hyungtaek Kim 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Thermal stress deformation is a disadvantage of the rotary air preheater, which results in leakages of fluids and decrease of efficiency of the thermal system. To evaluate the results of deformation during its operation, the temperature distribution of storage materials is calculated by solving a simplified model. In this developed method, the effect of dimensionless parameters on the temperature distribution of rotary air preheater was investigated and compared with the results of modified heat transfer coefficient method. By solving coordination, structural and geometrical equations, and boundary condition in thermal-elastic theory, the thermal stress distributions in rotary air preheater are obtained in an analytical method. Experimental results are obtained by employing factorial design values of rotary air preheater for the validation of the calculation data. Good agreement has been yielded by comparing the analytical data and experimental data. Therefore, some conclusions necessary to undertake an adequate adjustment of thermal stress deformation have also been formulated, and online monitoring of the clearance of radial seals is proposed.
Liu, Hongyu,Wu, Jianping,Liu, Cuiyun,Pan, Bingli,Kim, Nam Hoon,Lee, Joong Hee Elsevier 2018 Composites Part B, Engineering Vol.155 No.-
<P><B>Abstract</B></P> <P>Polyelectrolyte-decorated graphene with positive and negative charges was prepared using graphene oxide as a precursor along with polyallylamine hydrochloride and poly (styrenesulfonate sodium) as surface modifiers, respectively. Driven by an electrostatic interaction, the as-obtained polyelectrolyte-decorated graphene sheets were self-assembled via a layer-by-layer method, producing graphene based composite multilayers. Field emission scanning electron microscopy (FE-SEM) images showed that the surface of composite film exhibited a mass of characteristic wrinkles of graphene. Interestingly, the cross-sectional FE-SEM of the film exhibited an unstratified structure, indicating a good dispersion of graphene sheets in the composite film. The results of oxygen gas permeability testing demonstrated that the resulting composite films exhibited excellent oxygen gas barrier properties. The oxygen gas transmission rate (OTR) of the composite film with 24 bilayers was as low as 1.2 cm<SUP>3</SUP> m<SUP>-2</SUP> d<SUP>-1</SUP>∙atm<SUP>−1</SUP>, exhibiting potential for use in packaging applications.</P>
Active Suspension을 위한 직렬 탄성 액츄에이터 시뮬레이션
김지현(Ji-hyeon Kim),윤하늘(Ha-Nuel Yun),방진욱(Jin-Uk Bang),장홍위(ZHANG HONGYU),이장명(Jang-Myung Lee) 대한전자공학회 2018 대한전자공학회 학술대회 Vol.2018 No.11
Recently, actuators have been used in various fields and are being continuously developed. Actuators are mainly used in robots that require high positional accuracy and repeatability. Robust actuators have high control bandwidth and accuracy, while Series Elastic Actuators(SEA) allow flexible control with springs. Therefore, this paper proposes modeling and simulation of SEA for determining the spring constant used in SEA.
Jaeha Lee,Hyungsul Oh,Hongyu Kim,Woojong Park 한국산업경영시스템학회 2021 한국산업경영시스템학회 학술대회 Vol.2021 No.추계
Korea's defense industry has been fostered as a protection industry in which the government directly controls prices, quantities, and costs for the past 40 years, and it is deepening into a low-efficiency industrial structure. By implementing the Defense Industry Building Act in 2021, the government is creating a healthy ecosystem for the defense industry and strengthening its global competitiveness. In this study, based on KPC's Productivity Management System (PMS), a diagnostic model of defense companies that has been implemented since 2013, on-site diagnosis was performed from 4 to 28 days depending on the size of the company, and data was collected based on the results. For the effect of innovation capability on productivity performance, the causal relationship was analyzed through structural equation model path analysis. As a result, it suggests that defense materials suppliers should focus on which core processes to innovate and strengthen and improve their innovation capabilities.
Li, Peng,Chen, Kuo,Zhao, Lili,Zhang, Hongyu,Sun, Haixiang,Yang, Xiujie,Kim, Nam Hoon,Lee, Joong Hee,Niu, Q. Jason Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.166 No.-
<P><B>Abstract</B></P> <P>Hydrogen barrier properties are characteristic of polymeric materials prepared with graphene; thus, they can be considered as a good substitute for the metal body of the traditional hydrogen storage tank. Graphene oxide/polymer layer-by-layer self-assembling film based on noncovalent force shows good hydrogen gas barrier properties. However, the dense film structure can be broken when the film is placed in water environment, especially acidic or alkaline environment, which induces to the leak of the hydrogen gas. Herein, a modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled film for the hydrogen barrier was fabricated by the covalent bond self-assembled technology. Graphene oxide was modified with ethylene glycol diglycidyl ether to introduce epoxy groups that can react with polyethyleneimine to form covalent bonds. The modification time, modification pH value, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether were investigated in detail. Results indicate that the self-assembled films were prepared by covalent bonds between polyethyleneimine and modified graphene oxide. When the modification time was 6 h, pH value was 2, and the feed ratio of graphene oxide/ethylene glycol diglycidyl ether was 0.05/0.23, the hydrogen transmission rate of 10-bilayer modified graphene oxide/polyethyleneimine self-assembled films was 289 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa, which was decreased by 78.8% compared to that of the polyethylene terephthalate substrate films (1365 cm<SUP>3</SUP>/m<SUP>2</SUP>·24 h·0.1 MPa). Furthermore, the modified graphene oxide/polyethyleneimine reactive layer-by-layer self-assembled films exhibit acid-resistance, alkali-resistance, salt-resistance and thermal-resistance properties.</P>
John, Johnson V.,Uthaman, Saji,Augustine, Rimesh,Chen, Hongyu,Park, In-Kyu,Kim, Il Royal Society of Chemistry 2017 Journal of Materials Chemistry B Vol. No.
<P>A series of dual stimuli-responsive poly(l-histidine)n-<I>S-S</I>-polyurethane-<I>S-S</I>-poly(l-histidine)n [p(His)n-<I>SS</I>-PU-<I>SS</I>-p(His)n; <I>n</I> = 25, 35, 50, and 75] triblock copolymers that bear two pH-responsive p(His)n end-blocks and PU middle-blocks tethered by a redox-responsive disulphide linker have been synthesized. The resulting triblock copolymers self-assemble to form micelles, nanodaisies (NDs), of uniform size (∼100 nm) and efficiently encapsulate the anticancer drug doxorubicin (Dox) with a high drug loading content (∼19%). The <I>in vitro</I> release profile shows an enhanced release of Dox in an acidic environment in the presence of 10 mM glutathione. The <I>in vitro</I> cell viability assays performed in various cell lines show that the NDs have no acute or intrinsic toxicity. Confocal microscopy images and flow cytometry results show the pH-responsive cellular uptake of Dox-loaded NDs, accelerated at pH ≤ 5.0. The tumour accumulation and <I>in vivo</I> bio-distribution studies of near-infrared dye (IR-820)-labeled NDs show higher tumour accumulation in CT26 tumour-bearing mice within 72 h. Furthermore, the Dox-loaded NDs effectively inhibit the CT26 tumours, suggesting that they are promising nanocarriers for cancer therapy.</P>
Amplification of transglutaminase 2 enhances tumor-promoting inflammation in gastric cancers
Cho Sung-Yup,오유미,Jeong Eui Man,박상희,Dakeun Lee,Xiaorui Wang,Qiqi Zeng,Hongyu Qin,Fang Hu,Hui Gong,Xi Liu,Guanjun Zhang,나득채,이지은,채지수,서윤석,공성호,Hyuk-Joon Lee,Jong-Il Kim,박한수,Chengsheng Zhang,양한광,Charles Lee 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-
Tumor-promoting inflammation is a hallmark of cancer and is highly associated with tumor progression, angiogenesis, and metastasis. Tumor-associated macrophages (TAMs) are major drivers of tumor-promoting inflammation, but due to the complexity of the tumor microenvironment, the detailed regulatory mechanisms are still under investigation. Here, we investigated a novel role for transglutaminase 2 (TGM2) in the development of tumor-promoting inflammation and recruitment of TAMs to gastric cancer (GC) tissues. When estimated by array comparative genomic hybridization and droplet digital PCR, the copy numbers of the TGM2 gene were amplified in 13.6% (14/103) of GC patients and positively associated with TGM2 expression. Gene set enrichment analysis of expression microarray data for GC samples with high or low TGM2 expression showed that increased TGM2 expression was associated with tumor-promoting inflammation in GC. In addition, the expression of TGM2 was correlated with the expression of markers for macrophages, neutrophils, blood vessels, and lymphatic vessels. Overexpression of TGM2 in GC cells augmented the IL-1β-induced secretion of macrophage-recruiting chemokines and NF-κB activation. TGM2 protein levels were associated with the expression levels of the macrophage marker CD163 in human GC tissue samples. Moreover, GC patients with high expression of TGM2 had a worse prognosis than those with low expression of TGM2. These results suggest TGM2 as a novel regulator of the tumor microenvironment of GC and provide a promising target for constraining tumor-promoting inflammation.
John, Johnson V.,Chung, Chung-Wook,Johnson, Renjith P.,Jeong, Young-Il,Chung, Kyu-Don,Kang, Dae Hwan,Suh, Hongsuk,Chen, Hongyu,Kim, Il American Chemical Society 2016 Biomacromolecules Vol.17 No.1
<P>Smart delivery system of photosensitizer chlorin e6 (Ce6) has been developed for targeted photodynamic therapy (PDT). Simple self-assemblies of the mixtures comprising soybean lecithin derived phosphatidylcholine (PC), phosphatidylethanolamine-poly(L-histidine)(40) (PE-p-(His)(40)), and folic acid (FA) conjugated phosphatidylethanolamine-poly(N-isopropylacrylamide)(40) (PE-p(NIPAM)(40)-FA) in different ratios yield smart nanospheres characterized by (i) stable and uniform particle size (similar to 100 nm), (ii) positive surface charge, (iii) high hydrophobic drug (Ce6) loading efficiency up to 45%, (iv) covalently linked targeting moiety, (v) low cytotoxicity, and (vi) smartness showing p(His) block oriented pH and p(NIPAM) oriented temperature responsiveness. The Ce6-encapsulated vesicular nanospheres (Ce6@VNS) were used to confirm the efficiency of cellular uptake, intracellular distribution, and phototoxicity against KB tumor cells compared to free Ce6 at different temperature and pH conditions. The Ce6@VNS system showed significant photodynamic therapeutic efficiency on KB cells than free Ce6. A receptor-mediated inhibition study proved the site-specific delivery of Ce6 in targeted tumor cells.</P>