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Effect of Highly Pressurized Hydrogen Gas Charging on the Hydrogen Embrittlement of API X70 Steel
Dong-Su Bae,Chi-Eun Sung1,Hyun-Ju Bang,Sang-Pill Lee,Jin-Kyung Lee,In-Soo Son,조영래,Un-Bong Baek,Seung-HoonNahm 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4
During the use of API X70 steel as a pipeline structural material for the transportation of natural gas,hydrogen embrittlement can occur due to the hydrogen contained in natural gas. The aim of this study is toinvestigate the effects of the hydrogen content under high-pressure hydrogen gas conditions on the hydrogenembrittlement of air-cooled API X70 steel. The air-cooled API X70 steel was manufactured by hot rollingand was then air-cooled to room temperature. Tensile test specimens were held for 0 h, 1000 h, and 2000 hwithin a pressure vessel filled with 100% hydrogen gas at a gas pressure of 10 MPa, with the tensile teststhen performed at room temperature. The microstructure of the API X70 steel consists of coarse polygonalferrite, coarse pearlite, and fine acicular ferrite. The yield and tensile strength increased and elongationdecreased considerably after a holding time of 2000 h compared to those of 0 h and 1000 h within the pressurevessel. The morphology of the fracture surface changed from ductile to brittle upon hydrogen gas charging. Secondary cracks were observed in both of the hydrogen-gas-charged specimens. No external cracks wereformed on the surface of the tensile-tested specimen with a 0 h holding time; however, many external crackswere observed on the specimen surface subjected to hydrogen gas charging.
Electrical properties of the multilayered PZT/BaTiO₃/PZT thick films
Sung-Pill Nam,Sung-Gap Lee,Young-Hie Lee 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.1
Multilayered PZT/BaTiO₃/PZT thick/thin/thick films were fabricated by two different methods-thick films of Pb₁.₁(Zr0.52Ti0.48)O₃ by a screen printing method on alumina substrate electrode with Pt, thin films of BaTiO₃by a spin-coating method with PZT thick films and once more thick films of the PZT by a screen printing method on the BaTiO₃layer. We investigated the effect of phase, composition, and interfacial state of the BaTiO₃ thin film layers at the interface between the PZT thick films. The structural and the dielectric properties were investigated for the effect of various stacking sequences of sol-gel-prepared BaTiO₃ layers at the interface of the PZT thick films. The insertion of the BaTiO₃ interlayer yielded PZT thick films with homogeneous and dense grain structures regardless of the number of the BaTiO₃ layers. These results suggested that there is coexistence of the PZT phase and the BaTiO₃ phase or the presence of a modified BaTiO₃ at the interfaces between the PZT thick films. The leakage current density of a multilayered PZT-7 film is less that 1.5×10−9 A/cm2 at 5 V. Multilayered PZT/BaTiO₃/PZT thick/thin/thick films were fabricated by two different methods-thick films of Pb₁.₁(Zr0.52Ti0.48)O₃ by a screen printing method on alumina substrate electrode with Pt, thin films of BaTiO₃by a spin-coating method with PZT thick films and once more thick films of the PZT by a screen printing method on the BaTiO₃layer. We investigated the effect of phase, composition, and interfacial state of the BaTiO₃ thin film layers at the interface between the PZT thick films. The structural and the dielectric properties were investigated for the effect of various stacking sequences of sol-gel-prepared BaTiO₃ layers at the interface of the PZT thick films. The insertion of the BaTiO₃ interlayer yielded PZT thick films with homogeneous and dense grain structures regardless of the number of the BaTiO₃ layers. These results suggested that there is coexistence of the PZT phase and the BaTiO₃ phase or the presence of a modified BaTiO₃ at the interfaces between the PZT thick films. The leakage current density of a multilayered PZT-7 film is less that 1.5×10−9 A/cm2 at 5 V.
Lee, Sang-Pill,Yoon, Han-Ki The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.8
The thermodynamical estimation of the interfacial reaction and the impact properties of $Nb/MoSi_2$ laminate composites containing SiC, $NbSi_2$ or $ZrO_2$ particles are investigated. Laminate composites, which comprise alternating layers of $MoSi_2$ with the particle and Nb foil, were fabricated by the hot press process. It is clearly found out that the interfacial reaction of $Nb/MoSi_2$ can be controlled by the addition of $ZrO_2$ particle to the $MoSi_2$ phase. The addition of $ZrO_2$ particle increases both the impact value and the sintered density of Nb/McSij, The suppression of the interfacial reaction is caused by the formation of $ZrSiO_2$ in $MoSi_2-ZrO_2$ matrix mixture.
Pilot Case for Container Security Device (CSD) Based on Active RFID
Lee, Eun-Kyu,Moon, Young-Sik,Shin, Joong-Jo,Shon, Jung-Rock,Choi, Sung-Pill,Kim, Chae-Soo,Kim, Jae-Joong,Choi, Hyung-Rim The Korea Institute of Information and Commucation 2010 Journal of information and communication convergen Vol.8 No.2
CSD is Active RFID based Container Security Device which is proposed by the U.S Department of Home Security. It is mounted inside the container to sense opening of the container door. ConTracer is the CSD which is developed in this research whose major features are sensing door opening status as well as history inquiring on internal environment and shock to the container by mounting the temperature/ humidity/ shock sensors. Moreover, its RFID frequency bandwidth uses 433MHz and 2.4GHz to correspond actively to the frequency used by different countries. This paper introduces the development trend of CSD, compares the ConTracer which is developed thru this research and other company's CSD, and introduces CSD System which is designed and established using ConTracer. Finally, the implemented CSD System is verified by applying the demonstration service to container distribution between Korea and China.
Lee, Sang-Pill,Yoon, Han-Ki,Park, Won-Jo Korean Society of Ocean Engineers 2000 International journal of ocean engineering and tec Vol.3 No.1
The present study dealt with the relationships among the interfacial shear strength, the thickness of interfacial reaction layer and the impact value of $Nb/MoSi_2$ laminate composites. In addition, the tensile test was conducted to evaluate the fracture strain of $Nb/MoSi_2$ laminate composites. To change the thickness of the reaction layer, $Nb/MoSi_2$ laminate composites alternating sintered MoSi2 layers and Nb foils were fabricated as the parameter of hot press temperature. It has been found that the growth of the reaction layer increases the interfacial shear strength and decreases the impact value by localizing a plastic deformation of Nb foil. There also exist appropriate shear strength and the thickness of the reaction layer, which are capable of maximizing the fracture energy of $Nb/MoSi_2$.
Derivation of Induced Pluripotent Stem Cell–Like Cells from Jeju Black Cattle Cells
Sang-Gi Jeong,Seung-Eun Lee,Yun-Gwi Park,Yeo-Jin Son,Eun-Young Kim,Se-Pill Park 한국동물생명공학회(구 한국동물번식학회) 2017 Reproductive & Developmental Biology(Supplement) Vol.41 No.2
Jeju Black Cattle (JBC, endangered native Korean cattle), a species characterized by their pitch-black coat color, live in Jeju Special Self-Governing Province. Pluripotent stem cells (PSCs) derived from farm animals have potential for various applications in transgenic breeding, basic research and agriculture. However, there were a few reports for establishment of bovine induced PSC (iPSC) and their culture conditions were not optimized yet. In this study, JBC bull #5293 (date of birth, October 31, 2013) ear cells were transfected by retroviral vectors that include 5 pluripotent reprogramming factors, hOCT4, hSOX2, hKLF4, hc-MYC and hNANOG. The JBC cells were exposed to retrovirus in suspended state in a fibroblast culture medium (10% FBS+DMEM) for 3 h and then plated on culture dish (3×104 cells/60mm-dish). After three days, infected cells were dissociated and replated to a new feeder-free culture dish or mouse embryonic fibroblast (MEF) feeder cell dish (3×104 cells/60 mm-dish). And these cells were cultured in two different ES media (15% FBS+DMEM; 15% FBS or 20% SR+DMEM/F12; 20% SR) commonly supplemented with 5 ng/mL bFGF and 1,000 U LIF. Produced iPSC-like colony was separated by mechanical dissociation and transferred to a new MEF cell dish. In the result, cell aggregation before colony formation was predominantly appeared in 20% SR group compared with 15% FBS group, while the JBC cell growth was faster in 15% FBS group. In comparison of feeder-dependent or -free culture, differentiation was more frequently appeared in feeder-free condition. However, a iPSC-like colony was recovered in 15% FBS group under feeder-free culture. These iPSC-like colonies were maintained up to 3 passages. When we checked the pluripotent cell marker alkaline phosphatase (AP), the activity was strongly detected in 2nd passage JBC iPS-like cells. Further experiments were needed to find the better stable culture condition able to more passages culture (>15) for establishment of JBC-iPSCs.