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Sang-Woo Han,Seungcheol Shin,Hansol Kim,Geonho Lee,Jongho Jeon,Sangjun Han,Gyuyeol Bae,Jung-Ho Cho 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.25 No.5
Homogeneous and heterogeneous PAW (plasma arc welding) experiments were conducted to obtain weld beads with tensile strength of 100% or more compared to that of the base metal in lap joint fillet welding of CP (complex phase) 780 MPa grade high strength steel sheet. Homogeneous and heterogeneous welding mean welding technic without and with welding wire in each. Common basic welding parameters of both homogeneous and heterogeneous PAW wire were applied, including welding speed of 21 cm/min, arc length of 3.5 mm, weaving amplitude of 3 mm, work angle of 30°, and Ar 99.99% shielding gas with 12 L/min. In homogeneous PAW, the optimized additional welding conditions were a welding current of 90 and 95 A, push angle of 20°, and weaving frequency of 5 Hz. The fracture strengths of all the samples were less than that of the base metal, and all fractures occurred at the weld bead fusion zone due to insufficient reinforcement. In heterogeneous PAW, the optimized additional welding conditions were a welding current of 125 A, push angle of 0°, weaving frequency of 4 Hz, and wire feed speeds of 1.53 and 1.38 m/min. Moreover, the welding wire was fed from behind the arc. The fracture strengths of all the samples were greater than that of the base metal, and fractures occurred at the base metal or fusion zone boundary. The reason for higher tensile in heterogeneous PAW wire is deduced as the large cross-section area of reinforcement provided by the welding wire comparing to homogeneous welding. It is well known that small radius of welding heat source clearly produces narrow heat affected zone. Therefore, the PAW produces relatively narrower heat affected zone, then resulted as fully enough strength of weldment. This is another reason of the current achievement.
Bae, Woo-Chul,Lee, Han-Ki,Choe, Young-Chool,Jahng, Deok-Jin,Lee, Sang-Hee,Kim, Sang-Jin,Lee, Jung-Hyun,Jeong, Byeong-Chul The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.1
A soluble Cr(VI) reductase was purified from the cytoplasm of Escherichia coli ATCC 33456. The molecular mass was estimated to be 84 and 42 kDa by gel filtration and SDS-polyacrylamide gel electrophoresis, respectively, indicating a dimeric structure. The pI was 4.66, and optimal enzyme activity was obtained at pH 6.5 and $37^{\circ}C$. The most stable condition existed at pH 7.0. The purified enzyme used both NADPH and NADH as electron donors for Cr(VI) reduction, while NADPH was the better, conferring 61% higher activity than NADH. The $K_m$ values for NADPH and NADH were determined to be 47.5 and 17.2 umol, and the $V_max$ values 322.2 and 130.7 umol Cr(VI) $min^{-1}mg^{-1}$ protein, respectively. The activity was strongly inhibited by N-ethylmalemide, $Ag^{2+},\;Cd^{2+},\;Hg^{2+}$, and $Zn^{2+}$. The antibody against the enzyme showed no immunological cross reaction with those of other Cr(VI) reducing strains.
Heat Dissipation of Transparent Graphene Defoggers
Bae, Jung Jun,Lim, Seong Chu,Han, Gang Hee,Jo, Young Woo,Doung, Dinh Loc,Kim, Eun Sung,Chae, Seung Jin,Huy, Ta Quang,Van Luan, Nguyen,Lee, Young Hee WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.22
<P><B>Abstract</B></P><P>In spite of recent successful demonstrations of flexible and transparent graphene heaters, the underlying heat‐transfer mechanism is not understood due to the complexity of the heating system. Here, graphene/glass defoggers are fabricated and the dynamic response of the temperature as a function of input electrical power is measured. The graphene/glass defoggers reveal shorter response times than Cr/glass defoggers. Furthermore, the saturated temperature of the graphene/glass defoggers is higher than for Cr/glass defoggers at a given input electrical power. The observed dynamic response to temperature is well‐fitted to the power‐balance model. The response time of graphene/glass defogger is shorter by 44% than that of the Cr/glass defogger. The convective heat‐transfer coefficient of graphene is 12.4 × 10<SUP>−4</SUP> W cm<SUP>−2</SUP> °C<SUP>−1</SUP>, similar to that of glass (11.1 × 10<SUP>−4</SUP> W cm<SUP>−2</SUP> °C<SUP>−1</SUP>) but smaller than that of chromium (17.1 × 10<SUP>−4</SUP> W cm<SUP>−2</SUP> °C<SUP>−1</SUP>). The graphene‐based system reveals the lowest convective heat‐transfer coefficient due to its ideal flat surface compared to its counterparts of carbon nanotubes (CNTs) and reduced graphene oxide (RGO)‐based systems.</P>
Woo Seo, Yeon,Heum Park, Sung,Hyoung Chang, Seo,Hyun Jeong, Jung,Ho Kim, Kwang,Bae, Jong-Seong Elsevier 2017 Ceramics international Vol.43 No.11
<P><B>Abstract</B></P> <P>Single-component white-emitting Sr<SUB>3</SUB>Y(PO<SUB>4</SUB>)<SUB>3</SUB>:Dy<SUP>3+</SUP> phosphors were synthesized by a high-energy deformation process. X-ray diffraction patterns showed the resulting crystallized phase to be of cubic structure, space group I-43d (no. 220). The broad-band excitation spectra between 250 and 500nm were observed by monitoring the emission wavelength at 576nm, which matches well with commercial near-UV or blue LED chips. Under a 352nm excitation, the emission peaks were observed at 483nm (blue), 576nm (yellow), and 666nm (red), corresponding to the <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>15/2</SUB>, <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>13/2</SUB>, and <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>11/2</SUB> transitions of Dy<SUP>3+</SUP> ions. The optimized doping concentration of Dy<SUP>3+</SUP> ion was 8mol%. By controlling the Dy<SUP>3+</SUP> ion concentration, tunable colors from white to yellow were obtained in Sr<SUB>3</SUB>Y(PO<SUB>4</SUB>)<SUB>3</SUB>:Dy<SUP>3+</SUP> phosphors. These results reveal that studied materials may be a promising candidate for white LED applications.</P>
Sung Min Bae,Hee Jung Kim,Tae Young Shin,Jae Bang Choi,Yeon Ho Je,Byung Rae Jin,Soo Dong Woo 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.04
Polyhedrin is the major component of the nuclear viral occlusions produced during replication of the baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). To enhance the production efficiency of foreign protein in baculovirus expression system, the effects of various polyhedrin fragments were investigated by fusion expressing them with the enhanced green fluorescent protein (EGFP). Recombinant viruses were generated to express EGFP fused with polyhedrin fragments based on the previously reported minimal region for self-assembly and the KRKK nuclear localization signal (NLS). The marked increase of EGFP by these fusion expressions was confirmed through protein and fluorescence intensity analyses. Among the fusion-expressed protein in nucleus and cytoplasm, the most hyper-expression was observed in the fusion of amino acids 19 to 110 and 32 to 59 of polyhedrin. Also these fragments, some degradation of only the fused polyhedrin was observed in the fusion of amino acids 19 to 85 and 32 to 85. The production of E2 protein, which is a major antigen of classical swine fever virus, was dramatically increased by fusion expression with polyhedrin amino acids 19 to 110, and its preliminary immunogenicity was verified using experimental guinea pigs. The production of luciferase was approximately two folds increased by fusion expression with polyhedrin amino acids 32 to 59, and its activity was measured using Luminometer. This study suggests a new option for higher expression of useful foreign recombinant protein using the partial polyhedrin fusion expression in baculovirus.
Sung Min Bae,Soo Dong Woo 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.10
The baculovirus expression vector system (BEVS) is an effective and widely used method for the production of recombinant proteins in insect cells or larvae. However, the expression efficiency of foreign proteins using the polyhedrin promoter could not obtain the protein yields observed for native polyhedrin. To enhance the production efficiency of foreign protein in baculovirus expression system, the effects of various polyhedrin fragments were investigated by fusion expressing them with the enhanced green fluorescent protein (EGFP). Among the fusion-expressed protein in nucleus and cytoplasm, the most hyper-expression was observed in the fusion of amino acids 19 to 110 and 32 to 59 of polyhedrin. Additionally, the several proteins expressed by the partial polyhedrin-fused expression system was markedly increased. However, we identified that hyper-expression of target protein varied depending on the partial polyhedrin. Therefore, we constructed the virus inducible partial polyhedrin fusion transient expression system. This system amenable for screening of suitable partial polyhedrin to produce the target protein. The present study suggests a new option for higher expression of useful foreign recombinant protein using the partial polyhedrin fusion expression in baculovirus.