프리캐스트 포스트텐션 콘크리트 넓은 보-기둥 내부 접합부의 비탄성 거동

황재환,최윤철,김영찬,김대중,임재형,권기혁,문정호,이리형 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

The purpose of this paper is to evaluate the response of Precast Prestressed Concrete Interior Wide Beam-Column Joint subjected to cyclic lateral loading. To this end, the experimental investigation was performed with six half-scale specimens of interior connection. The design parameters are the beam to column depth ratio, and the number of tendons within column core. One of the specimens, IJH-6, is modeled for the connection at the top floor of a structure. The test results showed that the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional standard by ACI of acceptance criteria for concrete special moment frames.

포스트-텐션 프리캐스트 외부 넓은 보-기둥 접합부의 비탄성 거동

박상욱,최윤철,김영찬,김대중,임재형,권기혁,문정호,이리형 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

Experimental results from the cycle lateral load tests for post-tensioned precast wide beam-column connections were presented. Six exterior beam-column assemblages of half scale were tested in the laboratory. The specimens consist of U-shaped precast wide beams and concrete columns. The continuity at the beam-column joint is achieved with the topping concrete and post-tensioning. The specimens were designed with parameters of the beam-to-column depth ration and the number of tendons within column core. The test results showed that the post-tensioned precast wide beam-column connection satisfied the provisional standard by ACI of acceptance criteria for concrete special moment frames.

Simultaneous achievement of equiaxed grain structure and weak texture in pure titanium via selective laser melting and subsequent heat treatment

Li, Cheng-Lin,Won, Jong Woo,Choi, Seong-Woo,Choe, Jung-Ho,Lee, Sangwon,Park, Chan Hee,Yeom, Jong-Taek,Hong, Jae Keun Elsevier 2019 Journal of alloys and compounds Vol.803 No.-

<P><B>Abstract</B></P> <P>We used selective laser melting (SLM) to produce a three-dimensional specimen of pure Ti and found that an equiaxed grain structure and weak crystallographic texture could be achieved simultaneously via subsequent heat treatment. These traits have never been attained simultaneously in pure Ti prepared by traditional methods such as casting and rolling. This remarkable achievement was possible because recrystallization occurred during heat treatment without plastic deformation; such deformation introduces stored energy that drives recrystallization but inevitably causes a strong texture to develop. The occurrence of recrystallization was attributed to unique features of the SLM process including a very high cooling rate and repetitive layer stacking. These features generated considerable stored energy by affecting solidification and the <I>β</I> → <I>α</I> phase transformation. Steep in-grain orientation gradients and a fine lath structure also contributed to the activation of recrystallization by facilitating recrystallization nucleation. The heat-treated specimen showed tensile properties with significantly reduced anisotropy. This finding will provide new strategies for developing isotropic metallic materials and may introduce new applications of SLM.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A three-dimensional specimen of pure Ti was produced using selective laser melting. </LI> <LI> Both equiaxed structure and weak texture were achieved by subsequent heat treatment. </LI> <LI> These traits cannot be attained simultaneously by traditional manufacturing methods. </LI> <LI> This desirable ability of SLM originates from unique features of SLM process. </LI> <LI> The heat-treated sample had significantly reduced anisotropy in tensile properties. </LI> </UL> </P>

Investigation of natural convection heat transfer around a radial heat sink with a perforated ring

Li, Bin,Jeon, Sora,Byon, Chan Elsevier 2016 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.97 No.-

<P><B>Abstract</B></P> <P>Numerical studies were performed on natural convection heat transfer from radial heat sinks with perforated ring. The effects of perforation number (0–6), perforation diameter (0–3mm), and perforation length (1.5–6mm), and orientations angle (0–180°) on the thermal performance were investigated. The results show that radial heat sinks with a perforated ring obviously have better thermal performance than that with imperforated ring. Upwardly oriented radial heat sinks have the best thermal performance while sideward oriented radial heat sinks yield worst thermal performance. The geometric parameters of perforation is shown to affect the thermal performance of heat sink significantly at relatively higher heat transfer rate, especially for upward and sideward orientations. The thermal resistance of the radial heat sink with optimized perforated ring was shown to be less than that of imperforated ring by 17%, while reducing the mass of ring by up to 37%. This can be attributed to the unhindered natural convective flow through the perforation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The radial heat sink with concentric ring is considered. </LI> <LI> The effect of the perforation and orientation on the thermal performance is investigated numerically. </LI> <LI> The optimized perforated heat sink can reduce the thermal resistance and mass significantly. </LI> <LI> The performance enhancement is shown to be attributed to the unhindered natural convective flow. </LI> </UL> </P>

A combination of ferric nitrate/EDDS-enhanced washing and sludge-derived biochar stabilization of metal-contaminated soils

Yoo, Jong-Chan,Beiyuan, Jingzi,Wang, Lei,Tsang, Daniel C.W.,Baek, Kitae,Bolan, Nanthi S.,Ok, Yong Sik,Li, Xiang-Dong Elsevier 2018 Science of the Total Environment Vol.616 No.-

<P><B>Abstract</B></P> <P>In this study, soil washing and stabilization as a two-step soil remediation strategy was performed to remediate Pb- and Cu-contaminated soils from shooting range and railway sites. Ferric nitrate (Fe(NO<SUB>3</SUB>)<SUB>3</SUB>) and [<I>S,S</I>]-ethylenediamine disuccinate (EDDS) were used as washing agents, whereas three types of sludge-derived biochars and phosphogypsum were employed as soil stabilizers. While Fe(NO<SUB>3</SUB>)<SUB>3</SUB> extracted larger amounts of metals compared to EDDS (84% Pb and 64% Cu from shooting range soil; 30% Pb and 40% Cu from railway site soil), it caused severe soil acidification. Both Fe(NO<SUB>3</SUB>)<SUB>3</SUB> and EDDS washing enhanced the mobility of residual metals in the two soils, which in most cases could be mitigated by subsequent 2-month stabilization by sludge-derived biochars or phosphogypsum. By contrast, the metal bioaccessibility could only be reduced by soil washing. Nutrient-rich sludge-derived biochar replenished available P and K in both soils, whereas Fe(NO<SUB>3</SUB>)<SUB>3</SUB> washing provided available nitrogen (N). Soil amendment enhanced acid phosphatase activity but marginally improved soil dehydrogenase and urease activity in the treated soils, possibly due to the influence of residual metals. This study supported the integration of soil washing (by Fe(NO<SUB>3</SUB>)<SUB>3</SUB> or EDDS) with soil stabilization (by sludge-derived biochars or phosphogypsum) for accomplishing the reduction of metal mobility and bioaccessibility, while restoring the environmental quality of the treated soils.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe(NO<SUB>3</SUB>)<SUB>3</SUB> washing significantly removed Pb from shooting range and railway soils. </LI> <LI> Biochars neutralized acidic soil pH resulting from Fe(NO<SUB>3</SUB>)<SUB>3</SUB> washing. </LI> <LI> Phosphogypsum immobilized residual Pb by forming insoluble PbSO<SUB>4</SUB> precipitates. </LI> <LI> Sludge-derived biochars reduced metal mobility and enhanced soil quality. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Deubiquitination and Stabilization of PD-L1 by CSN5

Lim, Seung-Oe,Li, Chia-Wei,Xia, Weiya,Cha, Jong-Ho,Chan, Li-Chuan,Wu, Yun,Chang, Shih-Shin,Lin, Wan-Chi,Hsu, Jung-Mao,Hsu, Yi-Hsin,Kim, Taewan,Chang, Wei-Chao,Hsu, Jennifer L.,Yamaguchi, Hirohito,Ding Elsevier 2016 Cancer cell Vol.30 No.6

<P><B>Summary</B></P> <P>Pro-inflammatory cytokines produced in the tumor microenvironment lead to eradication of anti-tumor immunity and enhanced tumor cell survival. In the current study, we identified tumor necrosis factor alpha (TNF-α) as a major factor triggering cancer cell immunosuppression against T cell surveillance via stabilization of programmed cell death-ligand 1 (PD-L1). We demonstrated that COP9 signalosome 5 (CSN5), induced by NF-κB p65, is required for TNF-α-mediated PD-L1 stabilization in cancer cells. CSN5 inhibits the ubiquitination and degradation of PD-L1. Inhibition of CSN5 by curcumin diminished cancer cell PD-L1 expression and sensitized cancer cells to anti-CTLA4 therapy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TNF-α stabilizes cancer cell PD-L1 in response to chronic inflammation </LI> <LI> Activation of NF-κB by TNF-α induces CSN5 expression leading to PD-L1 stabilization </LI> <LI> CSN5 enzyme activity controls T cell suppression via PD-L1 deubiquitination </LI> <LI> Destabilization of PD-L1 by CSN5 inhibitor curcumin benefits anti-CTLA4 therapy </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Activation of formyl CH and hydroxyl OH bonds in HMF by the CuO(1 1 1) and Co₃O₄(1 1 0) surfaces: A DFT study

Ren, Jun,Song, Kai-he,Li, Zhenhuan,Wang, Qiang,Li, Jun,Wang, Yingxiong,Li, Debao,Kim, Chan Kyung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.456 No.-

<P><B>Abstract</B></P> <P>The first principle calculations with on-site Coulomb repulsion U terms were carried out to investigate the 5-hydroxymethylfurfural (HMF) adsorption on the CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces, two widely used oxidation catalysts. The adsorption of HMF molecule is energetically favoured in both cases, and HMF is more inclined to bridge adsorption via hydroxyl and formyl groups binding with surface O and metal sites. Moreover, the adsorption energy relies on both the coordination type of surface lattice oxygen to which the H atom binds and the formation of H-bond involving hydroxyl and formyl groups on the adsorbed HMF. Also, the hydroxyl OH bond breaking is very easy and is likely to be the first step in HMF oxidation, and then the OH insertion reaction to produce 2,5-furandicarboxylic acid (FDCA). The corresponding experimental results also show that the CuO and Co<SUB>3</SUB>O<SUB>4</SUB> surfaces are promising candidate catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces catalyze the oxidation of 5-hydroxymethylfurfural (HMF). </LI> <LI> Initial binding was formed through bridged-adsorption with O atoms in HMF. </LI> <LI> Oxidation reaction proceeds through the OH bond breaking pathway. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic potential energy diagram for the formyl CH and hydroxyl OH bonds of HMF dissociation on CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces. Obviously, the hydroxyl OH bond breaking is easier than that of the formyl CH bond on the two surfaces, which indicates the first step of oxidation of HMF to FDCA should be hydroxyl OH bond breaking.</P> <P>[DISPLAY OMISSION]</P>

Synthesis of cross-linked protein-metal hybrid nanoflowers and its application in repeated batch decolorization of synthetic dyes

Patel, Sanjay K.S.,Otari, Sachin V.,Li, Jinglin,Kim, Dong Rip,Kim, Sun Chang,Cho, Byung-Kwan,Kalia, Vipin C.,Kang, Yun Chan,Lee, Jung-Kul Elsevier 2018 Journal of hazardous materials Vol.347 No.-

<P><B>Abstract</B></P> <P>Herein, we report the preparation of a cross-linked protein-metal hybrid nanoflower (NF) system for laccase immobilization. The immobilized laccase showed effective encapsulation yield and activity recovery of 78.1% and 204%, respectively. The catalytic efficiency (<I>k</I> <SUB>cat</SUB> <I>V</I> <SUB>max</SUB> <SUP>−1</SUP>) of cross-linked NF (CL-NF) was 2.2-fold more than that of free laccase. The CL-NF also exhibited significantly higher stability towards pH and temperature changes. It exhibited excellent storage stability and tolerance towards solvents and inhibitors as compared with the free enzyme. After 10 cycles of reuses, the NF and CL-NF laccase showed 41.2% and 92.3% residual activity, respectively. The CL-NF showed high oxidation potential, 265% that of the free enzyme, towards phenolic compounds. The CL-NF laccase retained the residual decolorization efficiency of up to 84.6% for synthetic dyes under repeated batch conditions of 10 cycles. These results suggested that the preparation of CL-NF is an effective approach to enhance the enzymatic properties and has great potential in many industrial applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cross-linked (CL) laccase-metal hybrid nanoflower (NF) was prepared. </LI> <LI> The catalytic efficiency of CL-NF laccase was 2.2-fold higher than that of free laccase. </LI> <LI> CL-NF laccase showed 2.6-fold higher oxidation potential than free laccase towards phenolic compounds. </LI> <LI> Under repeated batch conditions, it retained high decolorization efficiency for synthetic dyes. </LI> </UL> </P>

Microstructural response of β-stabilized Ti–6Al–4V manufactured by direct energy deposition

Narayana, P.L.,Lee, Sangwon,Choi, Seong-Woo,Li, Cheng-Lin,Park, Chan Hee,Yeom, Jong-Taek,Reddy, N.S.,Hong, Jae-Keun Elsevier 2019 Journal of Alloys and Compounds Vol.811 No.-

<P><B>Abstract</B></P> <P>The present study describes the influence of β stabilizers (namely Fe and Cr) on the microstructural evolution and mechanical behavior of Ti–6Al–4V alloy fabricated by direct energy deposition. As the β stabilizer content increases from 1 to 4 wt%, the coarse columnar-grained morphology typical of additively manufactured Ti–6Al–4V is significantly refined, with a columnar-to-equiaxed transition. Furthermore, reheating of the deposited layers by the deposition of overlaying layers during fabrication induces an element partitioning effect, resulting in the formation of fine-grained α and isothermal ω. Hence, the heat profile during direct energy deposition resembles conventional solution and aging treatments. In addition, increasing the amount of β stabilizer steadily increases the room temperature strength of the Ti–6Al–4V alloy. The alloy with 4 wt% Fe showed the maximum strength, of ∼1.5 GPa.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The columnar-to-equiaxed transition of microstructure was achieved in the direct energy deposited Ti–6Al–4V alloy with the addition of Fe and Cr. </LI> <LI> The maximum room temperature strength of the Ti–6Al–4V with 4 wt% Fe alloy reaches ∼1.5 GPa. </LI> <LI> The reheating phenomenon caused by deposition of overlying layers during direct energy deposition resembles conventional solution and aging treatments. </LI> <LI> With an increasing amount of β stabilizer, the phase constituents in the Ti–6Al–4V alloy changed from αʹ .→ αʹ+α+ω+β → α+ω+β </LI> </UL> </P>

Highly stable flexible organic field-effect transistors with Parylene-C gate dielectrics on a flexible substrate

Kwon, Hyeok-jin,Ye, Heqing,An, Tae Kyu,Hong, Jisu,Park, Chan Eon,Choi, Yongseon,Shin, Seongjun,Lee, Jihoon,Kim, Se Hyun,Li, Xinlin Elsevier 2019 Organic electronics Vol.75 No.-

<P><B>Abstract</B></P> <P>Poly(chloro-p-xylene), or Parylene-C, is a polymeric insulating material that has good physical and chemical properties, such as a high dielectric strength, a pin-free surface, and good mechanical/chemical stability, but is difficult to apply to top-contact-structured OFETs since its hydrophobic and very rough surfaces hinder the growth of organic semiconductor crystals and promote the formation of interface traps. Herein, we applied a blend of PS and TIPS-PEN dissolved in 1,2,3,4 tetrahydronaphthalene to overcome these limitations of Parylene-C. To confirm the influence of this system, we analyzed the morphologies of crystals grown on Parylene-C surfaces modified by various organic and polymer materials, including methacryloxypropyltrimethoxysilane, hexamethyldisilazane, and dimethylchlorosilane-terminated polystyrene. Our investigation showed the ability of the PS:TIPS-PEN blend system to be used to overcome the above-described limitations of Parylene-C, and to manufacture top-contact OFETs displaying stable operation under gate-bias stress. Notably, we applied Parylene-C and this blend system in practical flexible OFETs that displayed highly stable properties.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Parylene-C film fabricated by CVD methods is characterized as gate insulating materials. </LI> <LI> Bottom gate top contact OFETs on hard/flexible substrate fabricated with TIPS-PEN: PS blend system and CVD based Parylene-C are reported. </LI> <LI> Morphological structure of TIPS-PEN is investigated using the tools including CPOM, SEM, AFM and 2D-GIXD. </LI> <LI> The OFETs show the mobility of 0.32, and 0.21 cm<SUP>2</SUP>/V in hard and flexible device type with negligible hysteresis both case. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>