• Journal of computational fluids engineering
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• v.1 no.1
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• pp.112-122
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• 1996

A finite element scheme using the concept of PISO method has been developed to solve the Navier-Stokes viscous flows in all speed range. This scheme includes development of new pressure equation that retains both the hyperbolic term related with the density variation and the elliptic term reflecting the incompressibility constraint. The present method is applied to the incompressible two-dimensional driven cavity flow problems(Re=100, 400 and 1,000). For compressible flows, the Carter plate problem(M=3 and Re=1,000) is computed. Finally, we have simulated the shock-boundary layer interaction(M=2 and Re=2.96×10/sup 5/), a more difficult problem, and compared its results with the experiment to demonstrate the shock capturing capability of the present solution algorithm.

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.169-174
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• 1995

A finite element scheme using the concept of PISO method has been developed to solve the viscous flow problems in all speed range. In this study, new pressure equation is proposed such that both the hyperbolic term related with the density variations and elliptic term reflecting the incompressibility constraint are included. Present method has been applied to incompressible flow in two-dimensional driven cavity(Re=100, 400 and 1,000), and its computed results are compared with other's. Also, Carter plate problem(M=3 and Re=1,000) is computed and the comparison is made with Carter's results. Finally, we simulate a shock-boundary layer interaction problem(M=2 and $Re=2.96{\times}10^5$) to illustrate the shock capturing capability of the present solution algorithm.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.481.1-481.1
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• 2014

Dye-sensitized solar cell (DSSC) has been extensively investigated as the next generation energy source. Despite attractive features of simple fabrication process and its economical efficiency, there are some problems such as low efficiency and low long-term stability. Many groups have attempted the proposed way to improve the cell efficiency and long-term stability such as low recombination rate between $TiO_2$ surface and electrolyte, the development of new dye molecules capable of light adsorption as broadly as possible, the fabrication of a solid-state DSSC by replacing the liquid electrolyte, and protective coating on glass. In this work, we confirmed new dye-coating conditions to maximize the dye adsorption between the dye and $TiO_2$ nanoparticle surface. The experiment results coating conditions with the coating temperature of $70^{\circ}C$, the dye concentration of 10 mM and the coating time of 3 min. Conditions have two times, three times cycle the experiment in progress efficiency rises.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.125.1-125.1
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• 2011

After a short description of the observatory, this presentation will highlight some of the most recent scientific achievements based on CFHT observations and how they benefit from the current instrumentation and novel observing modes proposed to the CFHT users. We will then move to the mid-term future with the development of new spectroscopic capabilities (visible wide-field FTS or near-IR spectro-polarimetry) and the study of a novel wide-field imager in the visible using Ground-Layer AO to provide unprecedented image quality on a large field of view. As an option for the long-term future, the concept of a next generation 10-m class telescope to replace the current CFHT 3.6-m will be described. An emphasis will be given on how CFHT is slowly morphing into an Asia-Pacific Rim observatory and on the role the Korean community could play in such an endeavor, from immediate access to first-class astronomical data to partnering with other nations in exciting developments.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.48.2-48.2
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• 2014

We present long-term optical to NIR data of the tidal disruption object, Swift J1644+57. The data were obtained with CQUEAN, UKIRT WFCAM observations. We analyze the morphology of the host galaxy of this object and decompose the bulge component using high resolution HST WFC3 images. We conclude that the host galaxy is bulge dominant. We also estimate the multi-band fluxes of the host galaxy through the light curves based on the long-term observational data. We fit the SED models to the multi-band fluxes of the host galaxy and determine its stellar mass. Finally, we estimate the mass of the central super massive black hole which is responsible for the tidal disruption event. The estimated stellar mass and black hole mass are ${\sim}10^{9.1}M_{\odot}$, ${\sim}10^{6.8}M_{\odot}$, respectively. We compare our results to other previous estimates.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.40-47
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• 2012

Hydrologic responses to the 4September 2010 $M_W$ 7.1 and 22 February 2011 $M_W$ 6.2 Canterbury earthquakes ranged from near instantaneous co-seismic liquefaction and changes in groundwater levels, to more sustained (days to months) changes in river discharge, spring flow and groundwater level. There was some indication of a sustained change in aquifer properties. This paper presents some of the hydrographs from the September and February events, and compares the response to each event, briefly taking into account the location of the bore relative to each earthquake, together with other factors such as borehole depth. Over the months following the September earthquake, a pattern emerged of relatively short-term responses in the shallow aquifers and in the confined aquifer system, close to the coast. A longer term response appears to have occurred in inland, deep bores, where water levels 12 months after the September event were (in some cases) up to 20 metres higher than would have been expected based on simple modelling (see Figure 3). Some examples of these are highlighted.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.131-143
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• 1998

This paper presents derivation of stage-discharge curve for Yangsan river. To derivate of stage-discharge lationship is one of the essential research areas in the water resource field. It provides reliable data a long term planning and hydrologic quantity on water resource development by quantitative analysis. The rating curve derivated through 15 discharge-observation on Yangsan river basin in 1997 has been estimated Q=1283.0262-1553.3158H+477.2702H2. According to the rating curve, the highest water level 2.6m, the limited water-level should be bound to the maximum of 2.6m. Before this research, stage-discharge curve of Yangsan river has not been developed, and only 15 discharge observation(hydrometry) has been carried out though this research. Therefore it seems necessary to collect observation data through a long term process to obtain a reliable rating curve equation.

• Current Optics and Photonics
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• v.7 no.6
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• pp.708-713
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• 2023

A robust all-fiber nonlinear amplifying loop-mirror-based mode-locked femtosecond laser is demonstrated. Power-dependent nonlinear phase shift in a Sagnac loop enables stable and power-efficient mode-locking working as an artificial saturable absorber. The pump power is adjusted to achieve the lowest intensity noise for stable long-term operation. The minimum pump power for mode-locking is 180 mW, and the optimal pump power is 300 mW. The lowest integrated root-mean-square relative intensity noise of a free-running mode-locked laser is 0.009% [integration bandwidth: 1 Hz-10 MHz]. The long-term repetition-rate instability of a free-running mode-locked laser is 10^-7 over 1,000 s averaging time. The repetition-rate phase noise scaled at 10-GHz carrier is -122 dBc/Hz at 10 kHz Fourier frequency. The demonstrated method can be applied as a seed source in high-precision real-time mid-infrared molecular spectroscopy.

• Clinical and Experimental Reproductive Medicine
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• v.41 no.3
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• pp.125-131
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• 2014

Objective: Under estrogen deficiency, blastocysts cannot initiate implantation and enter dormancy. Dormant blastocysts live longer in utero than normal blastocysts, and autophagy has been suggested as a mechanism underlying the sustained survival of dormant blastocysts during delayed implantation. Autophagy is a cellular degradation pathway and a central component of the integrated stress response. Reactive oxygen species (ROS) are produced within cells during normal metabolism, but their levels increase dramatically under stressful conditions. We investigated whether heightened autophagy in dormant blastocysts is associated with the increased oxidative stress under the unfavorable condition of delayed implantation. Methods: To visualize ROS production, day 8 (short-term dormancy) and day 20 (long-term dormancy) dormant blastocysts were loaded with $1-{\mu}M$ 5-(and-6)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-$H_2DCFDA$). To block autophagic activation, 3-methyladenine (3-MA) and wortmannin were used in vivo and in vitro, respectively. Results: We observed that ROS production was not significantly affected by the status of dormancy; in other words, both dormant and activated blastocysts showed high levels of ROS. However, ROS production was higher in the dormant blastocysts of the long-term dormancy group than in those of the short-term group. The addition of wortmannin to dormant blastocysts in vitro and 3-MA injection in vivo significantly increased ROS production in the short-term dormant blastocysts. In the long-term dormant blastocysts, ROS levels were not significantly affected by the treatment of the autophagy inhibitor. Conclusion: During delayed implantation, heightened autophagy in dormant blastocysts may be operative as a potential mechanism to reduce oxidative stress. Further, ROS may be one of the potential causes of compromised developmental competence of long-term dormant blastocysts after implantation.

• Nutrition Research and Practice
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• v.4 no.5
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• pp.393-399
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• 2010

Enteral nutritional support has been used via tube feeding for dysphagic stroke patients. We performed long and short term trials to evaluate the effects of commercial enteral nutritional supports on nutrition and health in stroke patients (mRS = 3~5) and quality of life in their caregivers. For a long term study, we recruited chronic (${\geq}$ 1 yrs) stroke patients (n = 6) and administered them 6 cans/day (1,200 kcal) of the commercial enteral formula N for 6 months according to IRB-approved protocol. We collected peripheral blood at 0, 2, 4 and 6 months. For a short term study, we recruited acute (${\leq}$ 3 months) stroke patients (n = 12) and randomly administered them two different commercial enteral formulas, N or J, for 2 weeks. We collected their blood at 0, 4, 7 and 14 day of the administration. Blood samples were analyzed to quantify 19 health and nutritional biomarkers and an oxidative stress biomarker, malondialdehyde (MDA). In order to evaluate quality of life, we also obtained the sense of competence questionnaire (SCQ) from all caregivers at 'before' and 'after trials'. As results, the enteral formula, N, improved hemoglobin and hematocrit levels in the long term trial and maintained most of biomarkers within normal ranges. The SCQ levels of caregivers were improved in the long term treatment (P < 0.05). In a case of the short term study, both of enteral formulas were helpful to maintain nutritional status of the patients. In addition, MDA levels were decreased in the acute patients following formula consumption (0.05 < P < 0.1). Most of health and nutrition outcomes were not different, even though there is a big difference in price of the two products. Thus, we evaluate the formula N has equal nutritional efficacy compared to the formula J. In addition, long term use of enteral formula N can be useful to health and nutrition of stroke patients, and the quality of life for their caregivers.