• Solar Energy
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• v.18 no.3
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• pp.185-195
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• 1998

The high viscosity of a LiCl(lithium chloride) solution as an absorbent in a solar energy regenerator causes a channeling phenomenon on the solar powered absorber plate surface when the solution is trickling down for regenerating itself. As this channeling phenomenon affects badly the heat and mass transfer, it is pertinent that this phenomenon be studied. Since regenerating performance of the solar energy regenerator depends on how the solution uniformly flows on the plate surface, an experiment on the structure of the plate surface for a model regenerator was conducted. Various shapes and structures of the plat surface down which the LiCl solution trickled were tested, and it was found that a tiered surface showed the highest water evaporation rate leaving more potential energy concentrating LiCl on the plate. It was also observed that the water evaporation rate depended largely on the pitch and height of the disturbing rods. In addition, the wider the contact area is and the longer the solution's flow time, the better the solar energy regenerator's performance.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.5
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• pp.484-491
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• 2017

Recent research has shown that quadrupole noise has a significant influence on the overall characteristics of flow-induced noise and on the performance of underwater appendages such as sonar domes. However, advanced research generally uses the Ffowcs Williams-Hawkings analogy without considering the quadrupole source to reduce computational cost. In this study, flow-induced noise is predicted by using an LES turbulence model and a developed formulation, called the formulation Q1As method to properly take into account the quadrupole source. The noise around a circular cylinder in an underwater environment is examined for two cases with different velocities. The results from the method are compared to those obtained from the experiments and the permeable FW-H method. The results are in good agreement with the experimental data, with a difference of less than 1 dB, which indicates that the formulation Q1As method is suitable for use in predicting quadrupole noise around underwater appendages.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.330-334
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• 2005

The effect of a new hepatoprotective agent, YH-439, on the hepatobiliary transport of a model organic cation (OC), TBuMA (tributylmethylammonium), was investigated. The area under the plasma concentration-time curve (AUC) from time zero to 4 h following iv administration of TBuMA (6.6 $\mu$mol/kg) was increased significantly when YH-439 in corn oil (300 mg/kg) was orally administered to rats 24 h prior to the experiment. Nevertheless, the cumulative biliary excretion of TBuMA remained unchanged. As a consequence, the apparent biliary clearance ($CL_b$) of TBuMA was decreased significantly as a result of YH-439 pretreatment, consistent with the fact that the in vivo excretion clearance of TBuMA across the canalicular membrane ($CL_{exc}$) was not changed by the pretreatment. The in vitro uptake of TBuMA into isolated hepatocytes was decreased by one half by the pretreatment, owing to a decrease in the apparent V$_{max}$ and $CL_{linear}$, but the $K_m$ for the process remained constant. Most interestingly, however, the sinusoidal uptake of glucose, a nutrient, into hepatocytes was not influenced by the pretreatment, suggesting the YH-439 pretreatment specifically impaired the sinusoidal uptake of OCs. Thus, the OC-specific inhibition of hepatic uptake, without influencing the uptake of glucose, a nutrient, appeared to be associated with the hepatoprotective activity of YH-439.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.99-106
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• 2011

The appearance of CSR changes the concept of the hull form design as well as structural design, since the application of CSR inevitably brings the lightweight increase of a ship. Keeping the original design constraints such as principal particulars, deadweight, and speed performance, designers have to increase the volume of the hull form. As a result, the entrance angle at bow end should become larger, which results in blunter waterline shape. For a slow and full ship having high $C_B$ more than 0.85, a new concept of bow shape has been required to alleviate the increase of wave-making resistance, since it is very difficult to improve waterline and frameline shape for such a full ship. In this paper a new bow shape of Capesize Bulk Carrier was developed to improve its wave-making characteristics without incompliance with the design constraints. For loading manual calculation, NAPA software was used. FLUENT6.3.26 and WAVIS1.4 were used to evaluate resistance performance of the subject hull forms. The newly designed hull form was tested at SSPA model basin for the final confirmation of resistance and propulsion performance of the ship. It was found that the new bow shape of a Capesize Bulk Carrier improved the resistance characteristics greatly compared to a conventional bulbous bow. The other benefits of new bow shape on the manufacturability were also investigated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.7
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• pp.1100-1103
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• 2015

The feasibility of incorporating cranberry concentrate (CC) as a value-added food ingredient in convenient food products was investigated using a model system of gelatin jelly. The pH, hardness, and lightness decreased while soluble solids content and redness increased significantly with increasing levels of CC added (P<0.05). In addition, 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activities increased significantly (P<0.05), and they were well correlated. Consumer acceptance test indicated that addition of CC to 6% had a favorable effect on consumer preferences for most attributes. Based on overall observations, jelly with 6% CC is recommended for taking advantage of functional properties of CC without sacrificing consumer acceptability.

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.1
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• pp.1-9
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• 1976

Using the computer programs for calculation of natural vibrations of ship's hull developed by the authors et al., an investigation into influences of various parameters on the accuracy of calculation was done through example calculations of a 30,000 DWT petroleum products carrier M/S Sweet Brier built by Korea Shipbuilding and Engineering Corporation. The methodical principles employed for the computer program development are as follows; (a) the ship system is reduced to an equivalent discrete elements system conforming to Myklestad-Prohl model, (b) the problem formulation is of transfer matrix method, and (c) to obtain solutions an extended $G\ddot{u}mbel's$ initial value method is introduced. The scope of the investigation is influences of number of discrete elements, choice of significant system parameters such as rotary inertia, bending stiffness and shear stiffness, and simplification of distributions of added mass and stiffness as trapezoidal ones referred to those of midship section on the calculation accuracy. From the investigation the followings are found out; (1) To obtain good results for the modes up to the seven-noded thirty or more divisions of the hull is desirable. For fundamental mode fifteen divisions may give fairly good results. (2) The influence of rotary inertia is negligibly small at least for the modes up to the 5- or 6- noded. (3) In the case of assuming either bending modes or shear modes the calculation results in considerably higher frequencies as compared with those based on Timoshenko beam theory. However, the calculation base on the slender beam theory surprisingly gives frequencies within 10% error for fundamental modes. (4) It is proved that to simplify distributions of added mass and stiffness as trapezoidal ones referred to those of midship section is a promising approach for the prediction of natural frequencies at preliminary design stage; provided good accumulation of data from similar type ships, we may expect to obtain natural frequencies within 5% error.

• Journal of The Korean Astronomical Society
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• v.50 no.5
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• pp.139-149
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400 nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence (<12 min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.43-52
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• 2017

In this paper, for the first time, the electroanalytical study of Triethylenediamine, TEDA was done on a typically graphene modified carbon paste electrode (Gr/CPE) in pH=10.5 of phosphate buffer solutions (PBS). The surface morphology of the bare and modified electrodes was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electro-oxidation of TEDA was investigated at the surface of modified electrode. The results revealed that the oxidation peak current of TEDA at the surface of Gr/CPE is 2.70 times than that shown at bare-CPE. A linear calibration plot was observed in the range of 1.0 to 202.0 ppm. In this way, the detection limit was found to be 0.18 ppm. The method was then successfully applied to determination of TEDA in aqueous samples obtained from two kinds of activated carbon from the masks of war. On the other hand, density functional theory (DFT) method at B3LYP/6-311++G** level of theory and a conductor-like Polarizable Continuum Model (CPCM) was used to calculate the $pK_a$ values of TEDA. The energies of lowest unoccupied molecular orbital ($E_{LUMO}$) and highest occupied molecular orbital ($E_{HOMO}$), gap energy (${\Delta}E$) and some thermodynamic parameters such as Gibbs free energy of TEDA and its conjugate acid ($HT^+$) were calculated. The results of calculated $pK_a$ were found to be in good agreement with the experimental values.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.53.2-53.2
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• 2016

We present surface photometry results of the dwarf galaxies in the nearby NGC 2784 galaxy group. We newly detected about 30 dwarf galaxy candidates at about 30 square degree area around the nearby NGC 2784 galaxy (D~10 Mpc and MV=-20.5) applying a visual inspection technique on the wide-field optical images taken by the KMTNet Supernova Program (KSP). Surface brightnesses of the objects estimated from the stacked-images with total exposure time of about 6 hours reach approximately ${\mu}V$ ~28.5 mag/arcsec2 around $3{\sigma}$ above sky background. The central surface brightness and the total absolute magnitude for the faintest candidate dwarf galaxy among about 40 galaxies including the previously known ones is ${\mu}0$, V~26.1 mag/arcsec2 and MV~-9.5 mag, respectively. The effective radii of the candidates are larger than ~200 pc. The radial number density of the dwarf galaxy candidates from the center of NGC 2784 is decreasing. The mean color (<(B-V)0>~0.7) and $S{\acute{e}}rsic$ structure parameters of the dwarfs, assuming them to be located in the NGC 2784 group, are well consistent with those of the dwarf galaxies in other groups (e.g. M83 group and the Local Group (LG)). The faint-end slope of the cumulative luminosity function (CLF) of the galaxies in NGC 2784 group is about ${\alpha}=-1.2$, which is steeper than that of the LG galaxies, but is much flatter than that of the CLF expected by a ${\Lambda}CDM$ model.

• Journal of the Korean Institute of Navigation
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• v.18 no.2
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• pp.91-109
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• 1994

Technological and organisational changes in transport system have introduced new dimension into port system development and inter-port competition. The quality of service now required by the customer is costly and not easily provided by small shipping companies and small ports. It has been suggested that in the future container shipping may be concentrated by space-sharing arrangements or actual mergers into the hands of a few mega-operators with the investment potential to provide total logistics networks. In order to compete effectively, high load factors will be essential and port concentration inevitable. A fa-voured few ports will become the load centres and other ports will assume a secondary feeder role. In this study, three questions are raised and attempts are made to answer them : (a) what is the new role of ports today ; (b) why should ports be engaged in this new role ; and (c) how can ports play this new role. In short, a modern port should be a service centre and a logistic platform for international trade and transport-a third generation port. Ports, in particular, have to make every effort to be competitive in the cost and quality of services and to make the port a transport and distribution service centre. For most ports, this is not an option but a must ; an essential requirement for survival in this win or lose situation. The best way to win is to maintain a close contact with port users, listen to them, discuss with them, help them and satisfy them. That is port marketing. Starting from the findings of port marketing, it is es-sential to work out appropriate development plans and marketing targets and to improve port competitive-ness. As an alternative method, a port competitiveness model is suggested, which may help port managers to make appropriate improvements.