Mix design of concrete for prestressed concrete sleepers using blast furnace slag and steel fibers

Shin, H.O.,Yang, J.M.,Yoon, Y.S.,Mitchell, D. Elsevier Science Publishers 2016 CEMENT AND CONCRETE COMPOSITES Vol.74 No.-

The application of ground granulated blast furnace slag (GGBFS) and steel fibers in prestressed concrete railway sleepers was investigated in this study. The use of GGBFS was considered as an eco-friendly material aimed at reducing CO<SUB>2</SUB> emissions and energy consumption as well as to enhance the durability performance of railway sleepers. Steel fibers improves the durability and structural performance in terms of crack control and reduction of spalling and can replace shear reinforcement. The mix proportions of the concrete incorporating GGBFS (56% GGBFS) and GGBFS with steel fibers (56% GGBFS and 0.75% steel fibers) were determined through a series laboratory tests and a life cycle assessment. These mixes satisfied the requirements of the Korean Railway Standard and resulted in improved flexural capacity as well as less CO<SUB>2</SUB> emissions compared with current railway sleepers. Using these mixes, a total of ninety prestressed concrete sleepers were produced in a factory under the same manufacturing process as current railway sleepers, and their mechanical properties as well as durability performance were evaluated. The mix with partial replacement of Type III Portland cement by GGBFS showed an improved resistance to chloride ion penetration and freeze-thaw cycles compared with the concrete used for current railway sleepers. However, these mixes were more vulnerable to carbonation. The mix with GGBFS and steel fibers (mix BSF) showed a slightly better durability performance than the mix with GGBFS only (mix BS), including better carbonation and freeze-thaw resistances. The mix BSF showed decreased chloride ion penetration depth than mix BS but showed a slightly higher chloride ion diffusion coefficient.

Focal localization of MukBEF condensin on the chromosome requires the flexible linker region of MukF

Shin, Ho‐,Chul,Lim, Jae‐,Hong,Woo, Jae‐,Sung,Oh, Byung‐,Ha Blackwell Publishing Ltd 2009 FEBS JOURNAL Vol.276 No.18

<P>Condensin complexes are the key mediators of chromosome condensation. The MukB–MukE–MukF complex is a bacterial condensin, in which the MukB subunit forms a V‐shaped dimeric structure with two ATPase head domains. MukE and MukF together form a tight complex, which binds to the MukB head via the C‐terminal winged‐helix domain (C‐WHD) of MukF. One of the two bound C‐WHDs of MukF is forced to detach from two ATP‐bound, engaged MukB heads, and this detachment reaction depends on the MukF flexible linker preceding the C‐WHD. Whereas MukB is known to focally localize at particular positions in cells by an unknown mechanism, <I>mukE</I>‐ or <I>mukF</I>‐null mutation causes MukB to become dispersed in cells. Here, we report that mutations in MukF causing a defect in the detachment reaction interfere with the focal localization of MukB, and that the dispersed distribution of MukB in cells correlates directly with defects in cell growth and division. The data strongly suggest that the MukB–MukE–MukF condensin forms huge clusters through the ATP‐dependent detachment reaction, and this cluster formation is critical for chromosome condensation by this machinery. We also show that the MukF flexible linker is involved in the dimerization and ATPase activity of the MukB head.</P><P><B>Structured digital abstract</B></P><P><P>: <I>mukBhd</I> (uniprotkb:), <I>mukF</I> (uniprotkb:) and <I>mukE</I> (uniprotkb:) <I>physically interact</I> () by <I>blue native page</I> ()</P></P>

Enhancing the confinement of ultra-high-strength concrete columns using headed crossties

Shin, H.O.,Yoon, Y.S.,Cook, W.D.,Mitchell, D. Elsevier 2016 ENGINEERING STRUCTURES Vol.127 No.-

This study investigates the influence of headed crossties on the confinement of 200MPa ultra-high-strength concrete (UHSC) columns. A Total of six UHSC columns confined by headed crossties (deformed reinforcing bars with heads welded on both ends) and seismic crossties, detailed with 90<SUP>o</SUP> bend anchorages alternated end to end, were constructed and tested under pure axial load. The amount and yield strength of transverse reinforcement were varied to determine the efficiency of headed crossties on the confinement of the UHSC columns. The columns with seismic crossties exhibited some loss in confinement due to the loss of anchorage of the 90<SUP>o</SUP> hooks that opened up before significant yielding of the crossties could occur. The relatively small heads used are capable of developing the yield force of high-strength transverse reinforcement in the UHSC columns. The use of high-strength headed crossties resulted in improved confinement compared to columns with high-strength seismic crossties resulting in improved post-peak performance of UHSC columns. A prediction model that accounts for the additional confinement pressure due to the bearing of the heads, brittle cover spalling and the stress-strain relationship of UHSC was used to predict the axial load-strain behavior of the UHSC columns.

Confinement of ultra-high-performance fiber reinforced concrete columns

Shin, H.O.,Min, K.H.,Mitchell, D. Applied Science Publishers ; Elsevier 2017 Composite structures Vol.176 No.-

This study investigates the axial load response of ultra-high-performance fiber-reinforced concrete (UHPFRC) columns with compressive strengths of 163 and 181MPa (design strengths of 150 and 180MPa). The UHPFRC used in this study had 1.5% of hybrid micro-steel fibers (1.0% of 19.5mm fibers and 0.5% of 16.3mm fibers) and did not contain coarse aggregate. A total of nine UHPFRC columns confined by transverse reinforcement with volumetric ratios of 0.9-9.9% and two different configurations (Types A and C) were tested under pure axial load to investigate the influence of these variables. The overall behavior of the UHPFRC columns was compared with the response of similar strength ultra-high-strength concrete (UHSC) columns having coarse aggregate. Test results showed a pronounced effect of the volumetric ratio of the transverse reinforcement on the confinement. Hybrid micro-steel fibers controlled brittle cover spalling very well and assisted the transverse confinement reinforcement after the peak load. Applicability of the confinement reinforcement equations in the current seismic design provisions for developing ductile behavior of the UHPFRC columns was investigated. The analytical study examined the ability of the existing high-strength concrete (HSC) confinement models for predicting the axial load response of the UHPFRC columns, and a prediction model that accounts for the effects of steel fibers and the stress-strain relationship of UHPFRC is proposed.

Effect of Steel Fibers on the Performance of Ultrahigh-Strength Concrete Columns

Shin, H. O.,Yoon, Y. S.,Lee, S. H.,Cook, W. D.,Mitchell, D. American Society of Civil Engineers 2015 Journal of materials in civil engineering Vol.27 No.4

Enhancing the performance of UHSC columns intersected by weaker slabs

Shin, H.O.,Yoon, Y.S.,Cook, W.D.,Mitchell, D. Elsevier 2016 ENGINEERING STRUCTURES Vol.127 No.-

This paper presents strategies for enhancing the transmission of ultra-high-strength concrete (UHSC) column loads through normal-strength concrete (NSC) slabs in the joint of slab-column connections. Parameters of the investigation were the ratio of column concrete strength to slab concrete strength (f<SUB>cc</SUB><SUP>'</SUP>/f<SUB>cs</SUB><SUP>'</SUP>), as well as the placement of steel fiber-reinforced concrete, and the installations of high-strength dowel bars and special structural steel inserts in the weak slab joint. The beneficial effects of using high-strength dowel bars and high-strength structural steel inserts on the ability to transmit axial loads from the UHSC columns through the weaker slabs were demonstrated. The benefits of placing steel fiber-reinforced concrete in the joint are not as significant as the additional high-strength steel reinforcement. Predictions of the effective concrete strengths using current code approaches and using equations proposed in the literature were compared to the experimental results. The results indicate that the design approach in the CSA Standard (CSA A23.3-14) and the method proposed by Kayani (1992), which is based on the a data fitting approach, provide reasonable lower bound predictions of the effective strength for the UHSC columns with weaker slab layers.

Laser Welding Application in Car Body Manufacturing

Shin, H.O.,Chang, I.S.,Jung, C.H. The Korean Welding and Joining Society 2003 International journal of Korean welding society Vol.3 No.1

Laser welding application for car body manufacturing has many advantages in the stiffness and the lightness of vehicle, the productivity of assembly line, and the degree of freedom in design. This presentation will express the innovation of car body manufacturing including parameter optimization, process modeling, and system integration. In this application the investment for systems was cut down dramatically by real time switching over the laser path between two welding stations. Points of technical discussion are as follows; optimization of parameters such as laser power, robot speed and trajectory, compact and useful design of jig & fixture to assure welding quality for 3 sheet-layer zinc-coated steel, system integration between 4㎾ Nd:YAG laser device and the other systems, on-line real time welding quality monitoring system, perfect safety standards for high power laser, minimization of consumption costs such as arc lamp, protective glass for optic, etc. This application was successfully launched mass production line in 2001. The laser-welded line of side panel consists of 122 stitches totally. And the length is about 2.4m.

Clinical treatment of mast cell tumor in dog

ShinHo Lee(ShinHo Lee),Chung Hui Kim(Chung Hui Kim),Jae-Hyeon Cho(Jae-Hyeon Cho) 한국예방수의학회 2023 예방수의학회지 Vol.47 No.2

A 11-year-old sexually intact female dog was presented because of a misshapen left elbow with a large mass. The masses on the elbow were diagnosed as high-grade canine mast cell tumor (cMCT) based on the cytological examination using fine-needle aspiration. Cytologically, the mass revealed moderate numbers of eosinophils, anisocytosis, anisokaryosis, and aberrant mitotic figures. The degree of cytologic dysplasia is diagnosed as moderate to severe. The blood analysis revealed low hematocrit and electrolytes. After examining the metastasis and surgical scope with radiographs and ultrasound, surgery was performed to removal the mass. Histopathologically, the mass revealed partially cytoplasmic granules, anisokaryosis of the nucleus, and mitotic counts. Scattered inflammatory cells and necrotic tissues were observed in the tumor. In this study, we found high-grade cMCT and treated the patient through a surgical approach.

Luminescent Properties of LaBO₃:RE<SUP>3+</SUP> (RE=Tb, Ce) Phosphors for White Light Emitting Diodes

Shinho Cho 한국태양광발전학회 2014 Current Photovoltaic Research Vol.2 No.2

Tb<SUP>3+</SUP>- or Ce<SUP>3+</SUP>-doped LaBO₃ phosphors were synthesized by a solid-state reaction process with different concentrations of activator ions. The XRD spectra showed the monoclinic LaBO₃ pattern with the main peak occurring at (014) plane, irrespective of the kind of activator ions. The crystallite size was determined by using the Scherrer formula, and the maximum was obtained with an activator concentration of 0.05 mol for both phosphors. The emission spectra of LaBO₃ phosphors doped with Tb<SUP>3+</SUP> ions under excitation at 269 nm exhibited three major emission bands at 488, 544, and 587 nm. The strongest emission was green at 544 nm owing to the <SUP>5</SUP>D₄-<SUP>7</SUP>F5 transition at a Tb<SUP>3+</SUP> ion concentration of 0.05 mol. For the Ce<SUP>3+</SUP>-doped LaBO₃ phosphors, one strong blue band centered at 469 nm and weak multipeaks were observed. These results suggest that the optimum green and blue emission can be realized by controlling the concentration and type of activator ions incorporated in the host crystal.

Properties of nitrogen and aluminium-codoped ZnO thin films grown with different nitrogen flow ratios for solar cell applications

Shinho Cho 한국물리학회 2010 Current Applied Physics Vol.10 No.3

The nitrogen and aluminium-codoped ZnO (NAZO) thin films are grown by rf magnetron sputtering system with the nitrogen flow ratio changing from 0% to 30%. All of the NAZO films show a strongly c-axis preferred orientation, while the values of the electron concentration are found to decrease with the increase of the nitrogen flow ratio, and they are determined as 1.5–27 × 1019 cm-3. The optical transmittance spectra indicate an average transmittance of about 95% in the visible range, and a red shift of the band gap energy is observed with increasing the nitrogen flow ratio. These results suggest that the nitrogen flow ratio is an important parameter to grow the high-quality NAZO films for the application of solar cells.