• Ocean Systems Engineering
• /
• v.8 no.3
• /
• pp.313-327
• /
• 2018

Meeting the touchdown point (TDP) target box is one of the challenges during catenary riser installation, especially for deep water or ultra-deep water riser systems. TDP location mismatch compared to the design can result in variation of riser configuration, additional hang-off misalignment, and extra bending loads going into the hang-off porch. A good understanding of the key installation parameters can help to minimize this mismatch, and ensure that the riser global response meets the design criteria. This paper focuses on investigating the potential factors that may affect the touchdown point location, and addressing the challenges both in the design stage and during installation campaign. Conventionally, the vessel offset and current are the most critical factors which may affect the TDP movement during installation. With the offshore exploration going deeper and deeper in the sea (up to 10,000ft), other sources such as the seabed slope and seabed soil stiffness are playing an important role as well. The impacts of potential sources are quantified through case studies for steel catenary riser (SCR) and lazy wave steel catenary riser (LWSCR) in deep water application. Investigations through both theoretical study and numerical validation are carried out. Furthermore, design recommendations are provided during execution phase for the TDP mismatch condition to ensure the integrity of the riser system.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1788-1793
• /
• 2008

Classical molecular dynamics simulations (MDS) were conducted to simulate nano-sized cluster collisions with a weakly attractive static surface. Energy exchanges associated with the cluster collision and the adhesion probability are discussed. Routes of the energy exchanges and the kinetic energy loss are vastly altered in their mode according to the cluster incident velocity. In the elastic collision regime ($V_0$<0.1), most incident kinetic energy is recovered into the rebounding kinetic energy, but a little loss in the incident kinetic energy causes the cluster adhesion. Dissipated kinetic energy is converted into the rotational energy. In the weakly plastic collision regime (0.1<$V_0$<0.3), the transition from elastic to plastic collision occurs, and a large part of the released potential energy is converted into rebounding translational energy. For strongly plastic collisions ($V_0$>0.3), permanent cluster deformation occurs with extensive collapse of the lattice structure inducing a solid-to-solid phase transition; moreover, most of the cluster kinetic energy is converted into cluster potential and thermal energy.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.5
• /
• pp.2885-2889
• /
• 2013

Goniothalamin is an active compound extracted from Goniothalamus griffithii, a local plant found in northern Thailand. Goniothalamin inhibits cancer cell growth but is also toxic to normal cells. The aims of this study were to identify the cytotoxic effect of goniothalamin and the mechanism of cell death in human HL-60 and U937 cells. Cytotoxicity was determined by MTT assay and cell cycle profiles were demonstrated by staining with propidium iodide (PI) and flow cytometry. Apoptosis was confirmed by staining with annexin V-FITC/propidium iodide (PI) and flow cytometry. Reduction of mitochondrial transmembrane potential was determined by staining with dihexyloxacarbocyanine iodide and flow cytometry and expression of Smac, caspase-8 and -9 was demonstrated by Western blotting. Goniothalamin inhibited growth of HL-60 and U937 cell lines. An increase of SubG1 phase was found in their cell cycle profiles, indicating apoptosis as the mode of cell death. Apoptosis was confirmed by the flip-flop of phosphatidylserine using annexin V-FITC/PI assay in HL60 and U937 cells in a dose response manner. Furthermore, reduction of mitochondrial transmembrane potential was found in both cell types while expression of caspase-8, -9 and Smac/Diablo was increased in HL-60 cells. Taken together, our results indicate that goniothalamin-treated human leukemic cells undergo apoptosis via intrinsic and extrinsic pathways.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.1
• /
• pp.183-187
• /
• 2005

Abstract The cancer chemopreventive potential of chitosanoligosaccharides was investigated by measuring the induction of quinone reductase and glutathione S-transferase activities and inhibition of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide I (1-${\kappa}$Da${\kappa}$Da) significantly induced glutathione S-transferase activity with a maximal 1.5-fold increase at 500 ${\mu}$g/ml, while chitosanoligosaccharide II (3-${\kappa}$Da${\kappa}$Da) (500 ${\mu}$g/ml) strongly induced quinone reductase (p<0.01) and glutathione S-transferase (p<0.005) activities. The in vitro incubation of rat liver microsomes with chitosanoligosaccharides I and II (2.5, 5, 50, and 500 ${\mu}$g/ml) showed a dose-dependent inhibiton of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide II was a more potent inhibitor of cytochrome P450 2B1 activity than chitosanoligosaccharide I. Accordingly, these findings suggest that chitosanoligosaccharides are potential chemopreventive agents.

• Proceedings of the Korea Society of Environmental Toocicology Conference
• /
• 2002.10a
• /
• pp.166-166
• /
• 2002

The response of environmental pollutants can be detected bioanalytically focusing on the source and matrices of concern. Cell culture bioassays are rapid and inexpensive, and thus have great potential for determination of environmental pollution. We have examined the estrogenic and dioxin-like activites of industrial wastewater using E-screen assay and EROD microbioassay. Influent and effluent wastewater were collected from four different industrial wastewater treatment plants, such as cosmetics, paints, textile producing and metal coating plant, and extracted using solid-phase extraction with Oasis＠HLB plus cartridge. Pollutants adsorbed to the cartridge were eluted with MTBE. MCF-7 cells were treated with extracts showed various estrogenic potential. The textile wastewater showed strong estrogenic activity and the others showed weak estrogenic activity, No effect was observed in the wastewater from paints producing plant. All extracts showed CYPIA inducing effects, indicating these samples contain dioxin-like chemicals. Bioanalytical results of effluents compared with influents could give us information about the incomplete wastewater treatment and biological potency caused by pollutants. [Supported by a Grant from the Korea Science and Engineering Foundation]

• Journal of Preventive Medicine and Public Health
• /
• v.38 no.4
• /
• pp.386-390
• /
• 2005

Influenza A viruses periodicall y cause worldwide epidemics, or pandemics, with high rates of illness and death. A pandemic can occur at any time, with the potential to cause serious illness, death and social and economic disruption throughout the world. Historic evidence suggests that pandemics occurred three to four times per century. In the last century there were three influenza pandemics. The circumstances still exist for a new influenza virus with pandemic potential to emerge an d spread. The unpredictability of the timing of the next pandemic is underlined by the occurrence of several large outbreaks of highly pathogenic avian influenza since the early 1980s. In 1999, the World Health Organization published the Influenza pandemic plan. The role of WHO and guidelines for national and regional planning. And in 2005, WHO revised the global influenza preparedness plan for new national measures before and during pandemics. This document outlines briefly the Korean Centers for Disease Control's plan for responding to an influenza pandemic. According to the new pandemic phases of WHO, we set up the 4 national levels of preparedness and made guidelines for preventing and control the epidemics in each phase. And also we described the future plans to antiviral stockpiles and pandemic vaccine development.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.21 no.1
• /
• pp.45-50
• /
• 2013

In this study, lumped-vortex element method and thin airfoil theory were used to analyze aerodynamic characteristics of airfoils with relative motion that had camber lines of NACA $44{\times}{\times}$ airfoil in 2-dimensional unsteady incompressible potential flow. Velocity disturbance due to airfoil was calculated by lumped-vortex element model and force distribution on airfoil by unsteady Bernoulli's equation. Variables in relative motion were considered the period p, the amplitude of flapping $A_f$ and pitching $A_p$, and the phase difference between flapping and pitching ${\phi}_p$ and the angle of attack ${\alpha}$. Due to movement of an airfoil, dag was induced in 2-dimensional unsteady incompressible potential flow. The numerical results show that the aerodynamic characteristics of the airfoil with flapping and pitching at the same time are illustrated. Especially the mean lift coefficient became smaller, but drag coefficient became larger.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.173-178
• /
• 2007

Time-lapse electrical resistivity measurements have been made in a scale model experiment for geological $CO_2$ sequestration in aquifer. Three types of $CO_2$ injection are tested in a water tank filled with glass beads. These are $CO_2$ dissolved into filtered tap water, $CO_2$ gas, and mineral oil. The mineral oil is a substitute for liquid phase of supercritical $CO_2$. For reconstructing three-dimensional resistivity images, we measure potential differences at 32 potential dipoles on the top surface of the tank due to two current dipoles on the front and back sides. The resultant resistivity images clearly show the movement of injected $CO_2$ in aquifer.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.822-826
• /
• 2008

We report the cathodoluminescence and aging properties of a series of green phosphors of formula $Sr_{1-x}M_xGa_2S_4$:Eu (x = 0.0-1.0, M = Ba or Ca) that have potential applications in field emission displays (FEDs). The series of phosphors was synthesized via NaBr-aided solid-state reactions in a flowing $H_2S$ stream. A low level ($\sim$20%) of Ba or Ca substitution for Sr in $SrGa_2S_4$:Eu maintains the orthorhombic phase of pure $SrGa_2S_4$:Eu phosphors. Further, a low level ($\sim$20%) of Ba or Ca substitution for Sr in $SrGa_2S_4$:Eu provides various green colors and sufficient brightness for FED applications. Substitution of Ba or Ca for Sr in $SrGa_2S_4$:Eu also improved the stability of the phosphor when it was operated under electron-beam irradiation of 5 kV.

• Journal of the Korean Chemical Society
• /
• v.11 no.4
• /
• pp.159-164
• /
• 1967

An exact expression of the titration fraction as a function of the potential is derived for the cases where the coefficients of the both half reactions involved in the titration are homogeneous. It shows that the potential is independent of the concentration of the reagents not only at the equivalence point but also at all titration fractions. The sharpness of the end point detection by potentiometric method is shown to depend not only on the difference of the normal potentials involved but also strongly on the number of electrons transferred in each half reaction. The inflexion point of the potentiometric titration curve is shown to be slightly off from the equivalence point, including the cases where the number of electrons involved are equal. Completeness of the reaction in the course of titration is analyzed, too, mostly in terms of equilibrium constant, thus most of the results are applicable to any type of equilibrium in a single phase with particular relationship of coefficients of chemical equation.