Effects of Cu and B addition on microstructure and mechanical properties of high-strength bainitic steels

Shin, S.Y.,Han, S.Y.,Hwang, B.,Lee, C.G.,Lee, S. Elsevier Sequoia 2009 Materials science & engineering. properties, micro Vol.517 No.1

Effects of Cu and B addition on microstructure and mechanical properties of high-strength bainitic steels were investigated in this study. Six kinds of steels were fabricated by controlling the amount of Cu and B addition, and their microstructures and tensile and Charpy impact properties were investigated. Their effective grain sizes were also characterized by the electron back-scatter diffraction analysis. The tensile test results indicated that the B- or Cu-containing steels had the higher yield and tensile strengths than the B- or Cu-free steels because their volume fractions of acicular ferrite and martensite were quite high. The B- or Cu-free steels had the higher upper shelf energy than the B- or Cu-containing steels because of their lower volume fraction of martensite. In the steel containing 10ppm B without Cu, the best combination of high strengths, high upper shelf energy, and low energy transition temperature could be obtained by the decrease in effective grain size due to the presence of acicular ferrite having fine effective grain size.

protoplast-fusion에 依한 澱粉에서 Ethanol의 單段醱酵能 酵母 開發 : I. Characteristics of two yeast strains and conditions for the protoplast formation and reeneration as a preliminary step in interspecific protoplast-fusion I. Interspecific Protoplast-fusion 을 爲한 酵母菌林의 諸特性과 Protoplast 調製 및 Regeneration 條件

吳秉夏,黃殷成,李炯周,李啓瑚,朴官和,張海東,徐鉉昌 서울大學校農科大學 1984 서울대농학연구지 Vol.9 No.1

澱粉으로 부터의 alcohol 醱酵能을 增進시키기 爲하여 澱粉糖化性 菌株인 Saccharomyces diastaticus와 優秀한 alcohol 醱酵性 菌株인 Saccharomyces uvarum을 母菌株로 하여 이들간의 同屬異種間 原形質融合(interspecific protoplast fusion)을 通한 優秀한 澱粉醱酵 性 alcohol 生産性 菌株를 새로이 開發할 目的에서 다음과 같은 一漣의 實驗結果를 얻었다. S. diastaticus의 醱酵液과 S. diastaticus+S. uvarum 混合醱酵液의 風味特性등을 確認하였다. 風味成分 抽出은 methylene chloride와 diethylether를 가지고 neutral flavor fraction과 acidic flavor fraction으로 나누었고 gas chromatography를 通하여 同定 및 定量하였다. Neutral flavor fraction의 경우 S. diastaticus+S. uvarum 混合醱酵液이 S. diastaticus 醱酵液보다, ester成分中에서는 ethyl acetate와 ethyl undecanoate가 더 많았고, alcohol 成分中에서는 n-propanol과 n-butanol이 더 많았다. Acidic flavor fraction의 경우 C??~C?? fatty acid가 同定 및 定量되었는데 S. diastaticus+S. uvarum 混合醱酵液이 S. diastaticus 醱酵液보다 lauric acid, caprylic acid, capric acid 含量이 두드러지게 많았다. S. diastaticus의 glucoamylase 生産性, glucoamylase의 分離 精製, 酵素力價 그리고 酵素學的 特性에서 optimum pH는 5.0, optimum temperature는 55℃ 이었다. S. diastaticus와 S. uvarum을 母菌株로 이들 간의 protoplast fusion을 위한 基礎的인 硏究로서 두 菌株의 諸特性과 protoplast調製의 最適條件을 決定하고 protoplast의 regeneration 條件의 確立을 도모하였다.두 菌의 生育曲線에서 모두 培養開始 7~8 時間만에 對數期 中期에 到達되었으므로 protoplast 調製는 이 時期의 細胞를 쓰기로 하였다. Generation time은 S. diastaticus가 1.04, S. uvarum이 1.38 時間이었다. 細胞의 크기는 S. diastaticus 44.10?㎛³, S. uvarum 99.67㎛³로 S. uvarum이 2倍나 컸다. DNA 含量은 細胞 當 S. diastaticus 44.3fg, S. uvarum 37.6fg이었다. 30% glucose 및 soluble starch에 대한 두 菌株의 ethanol 醱酵能은 glucose에 對하여 S. uvarum 11.4%, S. diastaticus 8.9% 이었고 soluble starch에 對하여는 S. diastaticus 만이 6.9%이었다. 두 菌株는 generation time, 細胞크기 및 DNA 含量 等으로 보아 diploid strain임을 알 수 있었고, 融合株 選拔을 위한 marker 로는 Sacch. uvarum의 melibiose 資化能의 차이를 利用할 수 있음을 밝혔다. Protoplast의 調製에는 β-glucuronidase와 Zymoyase를 使用하였는데 두 酵素 反應最適條件은 β-glucuronidase는 pH 8.0에서 10% 濃度의 溶液으로, Zymolyase는 pH7.5에서 20㎛/ml의 濃度의 溶液으로 하여 모두 70分間 處理하는 것으로 決定하였으나 이 정도의 處理時間에서는 protoplast가 극히 不安定하게 되어 regeneration frequency가 떨어지는 것을 確認하였으며, 特히 Zymolyase 處理로 얻어진 protoplast의 regeneration率이 낮은 것은 Zymolyase中에 不純物로 微量 混在한 protease가 protoplast의 노출된 membrane-bound protein을 分解함으로써 protoplast를 破壞시키기 때문인 것으로 추측되었다. 融合實驗에 利用할 수 있을 정도의 regeneration frequency를 얻기 위해서는 Zymolyase를 45分間 處理하여 얻은 protoplast를 1.5%의 polyvinylpyrrolicone이 加해진 OYPD培地에서 重層法으로 展開하여 regeneration시키는 것이 좋은 것으로 판명되었다. As preliminary steps of protoplast fusion between Saccharomyces diastaticus and S. uvarum to develop a fusant of higher ethanol production from starch, characteristics of the two presumptive parent strains, optimal conditions for protoplast preparation and conditions for highrer regeneration frequency were investigated. To determine flavor characteristics of the parent strains, neutral and acidic flavor fractions were extracted from liquids fermented by S. diastaticus and S. diastaticus + S. uvarum with methylene chloride and diethly ether. The liquid by the mixed culture produced more ethly acetate, ethyl undecanoate, n-propanol, n-butanol, lauric acid, caprylic acid and capric acid than that by S. diastaticus. Glucoamylase from S. diastaticus was purified and activity, productivity, and characteristics were determined. Optimum conditions for the enzyme were pH 5.0 and 55℃. The two strains reached logarithmic phase in 7-8h during growth and the generation time was 1.04 in S. diastaticus and 1.38 in S. uvarum. Cell size and DNA content per cell of S. diastaticus were 44.10㎛³and 44.3 fg, and for S. uvarum, 99.67㎛³and 37.6fg. Ethanol productivities of S. diastaticus were 8.9% from 30% glucose and 6.9% from 30% starch and 11.4% from glucose with S. uvarum. Through determination of generation time, cell size, and DNA content per cell, both strains appeared as diploids, and differences in assimilability of melibiose and soluble starch of the two strains were selected as markers to determine the fusant. The optimal condition for protoplast formation was treatment of both strains with 10% ß-glucuronidase at pH 8.0 or 20㎍/ml Zymolyase at pH 7.5 for 70 min. While the regeneration frequencies were very low at 70min exposure to Zymolyase because of the instability of protoplasts, the yeasts treated for 45min were better for regeneration. The regeneration frequencies were also enhanced by 3-6 times when the regeration was carried out with 1.5% polyvinylpyrrolidone which stabilized protoplasts.

HIV 감염진단 표준화를 위한 정도관리(Quality Assurance) 프로그램 개발

이주실,박근용,김성순,강춘,김옥진,서순덕,박혜경,최병선,남정구,도경미,구본기,김현숙,임종백,조권,황유성,황병갑,이용래 국립보건연구원 1999 국립보건원보 Vol.36 No.-

Raised Source-Drain Transistors in a Cell and Support Area with Co-Silicide for 88-nm DRAM Technology and Beyond

Y.M. Choi,B.J. Park,D.H. Kim,D.I. Kim,D.S. Hwang,H. K. Hwang,H.J. Kim,H.S. Kim,I.B. Chung,J.M. Park,J.W. Lee,J.Y. Kim,Kinam Kim,M.H. Jo,정문영,N.J. Kang,S.E. Kim,Y.J. Park,Y.S. Hwang 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.1

Full integration of a 512-Mb dynamic random access memory (DRAM) using both a raised sourcedrain (S/D) in a cell and a support area with additional Co silicidation in the support area is successfully performed for the first time at an 88-nm technology node. The Co-silicided support transistors in the DRAM circuit can be made by using the silicidation-blocking-layer method which keeps the cell array from silicidation. Raised S/D transistors using Si selective epitaxial growth (SEG) demonstrate good short-channel eect (SCE) immunity and a Co-silicided S/D in the support transistors exhibits an excellent current driving capability and reduced S/D sheet resistance, even for very small dimensions.

Progress in the development of heating systems towards long pulse operation for KSTAR

Kwak, J.G.,Bae, Y.D.,Chang, D.H.,Chang, D.S.,Hong, B.G.,Hwang, C.K.,In, S.R.,Jeong, S.H.,Jin, J.T.,Jung, K.S.,Kim, B.R.,Kim, J.,Kim, S.K.,Kim, T.S.,Lee, D.W.,Lee, K.W.,Oh, B.H.,Seo, C.S.,Seo, M.S.,Yoo International Atomic Energy Agency 2007 Nuclear fusion Vol.47 No.5

<P>Construction of the Korea superconducting tokamak advanced research (KSTAR) tokamak is in its final phase. For the long-pulse KSTAR discharges, the ion cyclotron range of frequencies (ICRF) and neutral beam injection (NBI) heating systems are expected to play important roles through a selective heating of ions and electrons, control of the plasma pressure and current profiles, a core fuelling and beam diagnostics for the KSTAR. In addition, the ICRF system is expected to be used for possible discharge cleaning and assisting in the tokamak startup. In this paper, the recent progress in the development of the ICRF and the NBI heating systems is described. The four-strap ICRF antenna has been successfully tested for a voltage up to 41 kV for a pulse length of 300 s (to 46 kV for 20 s) in a test chamber. A prototype KSTAR NBI system has been developed. At present, the system has successfully produced a 1 MW beam power for 200 s and a 3.5 MW output beam power for 4 s.</P>

Curcumin suppresses the TPA-induced invasion through inhibition of PKCα-dependent MMP-expression in MCF-7 human breast cancer cells

Kim, J.M.,Noh, E.M.,Kwon, K.B.,Kim, J.S.,You, Y.O.,Hwang, J.K.,Hwang, B.M.,Kim, B.S.,Lee, S.H.,Lee, S.J.,Jung, S.H.,Youn, H.J.,Lee, Y.R. G. Fischer 2012 Phytomedicine Vol.19 No.12

Curcumin (diferuloylmethane) is a polyphenol derived from the plant turmeric (Curcuma longa), which is commonly used as a spice. Although anti-carcinogenic, anti-oxidant, anti-inflammation, and anti-angiogenic properties have been reported, the effect of curcumin on breast cancer metastasis is unknown. Matrix metalloproteinase-9 (MMP-9) is a major component in cancer cell invasion. In this study, we investigated the inhibitory effect of curcumin on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced MMP-9 expression and cell invasion and the molecular mechanisms involved in MCF-7 cells. Our results showed that curcumin inhibits TPA-induced MMP-9 expression and cell invasion through suppressing NF-κB and AP-1 activation. Also, curcumin strongly repressed the TPA-induced phosphorylation of p38 and JNK and inhibited TPA-induced translocation of PKCα from the cytosol to the membrane, but did not affect the translocation of PKCδ. These results indicate that curcumin-mediated inhibition of TPA-induced MMP-9 expression and cell invasion involves the suppression of the PKCα, MAPK and NF-κB/AP-1 pathway in MCF-7 cells. Curcumin may have potential value in restricting breast cancer metastasis.

비틀림각에 따른 HWAT의 공력특성 전산해석

이명수(M. S. Lee),유성수(S.S. Yoo),황도연(D.Y. Hwang),한병윤(B.Y. Han),박형구(H. K. Park) 한국전산유체공학회 2009 한국전산유체공학회 학술대회논문집 Vol.2009 No.11

The objective of this study is 10 investigate aerodynamic characteristics of a Horizontal-axis wind turbines(HAWT), using CFD method with a commercial code STAR-CCM+ version 3.06. To verify the reliability of the computations, the CFD results are compared with the experimental ones of the National Renewable Energy Laboratory(NREL) Phase Ⅵ HAWT. For the comparison and examination of aerodynamic characteristics, the existent shape with a predesigned twist angle was replaced by the one with one-dimensional linear twist angle. In this study, the pressure contour and stream line around the blade were analyzed as main focus. Through this study the more efficient shape of airfoil is suggested with consideration of manufacturing cost.

Structural and optical properties of solvothermally synthesized ZnS nano-materials using Na₂S.9H₂O and ZnSO₄.7H₂O precursors

Hwang, B.H.,Xu, H.,Park, S.J.,Choi, S.E.,Nahm, S.,Hong, Y.W.,Paik, J.H.,Shin, T.H.,Kang, J.S. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.10

Hexagonal wurtzite (HWZ) ZnS nanorods were formed in specimens with a S/Zn ratio of 1.3, synthesized at temperatures ≥200<SUP>o</SUP>C in a solution containing 80vol% water and 20vol% of ethylenediamine (EN). In contrast, HWZ ZnS nanoparticles were formed in specimens synthesized at temperatures lower than 200<SUP>o</SUP>C. Also, cubic zinc blende (CZB) ZnS nanoparticles were formed in specimen synthesized in water. The absorption peak for the HWZ nanorods and CZB ZnS nanoparticles was at wavelength of 325nm and 339nm, respectively, indicating that the band gap energy of the former is larger than that of the latter. Moreover, the HWZ ZnS exhibited two emission peaks at 474nm and 580nm. The peak at 474nm is attributed to Zn vacancies but the origin of the peak at 580nm remains undetermined. Since the intensity of the emission peak at 580nm was significantly higher for the HWZ nanoparticles than for nanorods, this peak might be associated with defects in the HWZ ZnS nanoparticles.

Decomposition of excess sludge in a membrane bioreactor using a turbulent jet flow ozone contactor

Hwang, B.K.,Son, H.S.,Kim, J.H.,Ahn, C.H.,Lee, C.H.,Song, J.Y.,Ra, Y.H. Korean Society of Industrial and Engineering Chemi 2010 Journal of industrial and engineering chemistry Vol.16 No.4

<P>We have investigated the decomposition of excess sludge generated in a membrane bioreactor using a turbulent jet flow ozone contactor (TJC), which induced both hydrodynamic cavitation and ozonation reactions. We monitored the effects of various TJC operating parameters on the properties of the sludge, including the particle sizes, the particle size distribution, and the levels of soluble COD, total COD, and mixed liquor suspended solids. The TJC enhanced the degree of sludge reduction while consuming less energy, relative to conventional ozonation treatment systems, because of the synergic effects of hydrodynamic cavitation and zonation. The hydrodynamic cavitation generated in the TJC increased the ozone mass transfer efficiency, which in turn promoted the rate of disintegration and solubilization of the sludge particles. Crown Copyright (C) 2010 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry. All rights reserved.</P>

여대생의 우울, 스트레스와 문제도박과의 관계

하주희,차민주,조에스더,조세빈,홍소리,황정민,박지윤,강하영,노규상 이화여자대학교 간호과학대학 2015 이화간호학회지 Vol.- No.49

Purpose: The purpose of this study was to learn about problem-gambling level, depression and stress among female college students. Method: In this cross-sectional design study, a convenient sample of 325 female college students were recruited between September and October, 2014. Measurement used for this study were the CPGI(Canadian Problem Gambling Index), the CES-D(Center for Epidemiologic Studies Depression Scale), and the Life stress scale for college students. Data were statistically analyzed using descriptive statistics, t-test, ANOVA and chi-square test. Result: About 58.5 percent of the participants had experience of gambling; lottery was the most frequently used gambling among participants. 36 participants(11.1%) were problem gamblers. Relationship of smoking status to problem gambler group was statistically significant. There were statistically significant relationships among problem-gambling level(Non-problem, Low-risk, Moderate-risk, High-risk), depression and stress. The problem gambler group had significantly higher trait stress scores compared to the normal group. Conclusion: Problem gambling was a risk factor for both depression and stress among female college students. The proposals of this study are as follows; first, in depth-research are required with more expanded sampling as sample of this study was conveniently gathered, it is hard to generalize the result. Second, a problem gambling prevention program is recommended for low-risk problem gamblers as they have risk to become problem gambler later. Third, nursing interventions for problem gamblers should be investigated with regard to depression and stress level.