• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.2
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• pp.145-152
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• 2012

As the problems of global warming are brought up recently, many skillful solutions for developing new renewable energy are suggested. One of the most remarkable things is ocean energy. Korea has abundant ocean energy resources owing to geographical characteristics surrounded by sea on three sides, thus the technology of commercialization about tidal current power, wave power is demanded. Especially, Tidal energy conversion system is a means of maintaining environment naturally. Tidal current generation is a form to produce electricity by installing rotors, generators to convert a horizontal flow generated by tidal current into rotating movement. According to rotor direction, a tidal current turbine is largely distinguished between horizontal and vertical axis shape. Power capacity depends on the section size crossing a rotor and tidal current speed. We therefore investigated three dimensional flow analysis and performance evaluation using commercial ANSYS-CFX code for an 100 kW class horizontal axis turbine for low water level. Then We also studied three dimensional flow characteristics of a rotating rotor and blade surface streamlines around a rotor. As a result, We found that torque increased with TSR, the maximum torque occurred at TSR 3.77 and torque decreased even though TSR increased. Moreover we could get power coefficient 0.38 at designed flow velocity.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.177-189
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• 2012

Evaluation of three-dimensional ore body modeling has been performed by applying the geostatistical integration technique to multiple geophysical (electrical resistivity, MT) and geological (borehole data, physical properties of core) information. It was available to analyze the resistivity range in borehole and other area through multiple geophysical data. A correlation between resistivity and density from physical properties test of core was also analyzed. In the case study results, the resistivity value of ore body is decreased contrast to increase of the density, which seems to be related to a reason that the ore body (magnetite) includes heavy conductive component (Fe) in itself. Based on the lab test of physical properties in iron mine region, various geophysical, geological and borehole data were used to provide ore body modeling, that is electrical resistivity, MT, physical properties data, borehole data and grade data obtained from borehole data. Of the various geostatistical techniques for the integrated data analysis, in this study, the SGS (sequential Gaussian simulation) method was applied to describe the varying non-homogeneity depending on region through the realization that maintains the mean and variance. With the geostatistical simulation results of geophysical, geological and grade data, the location of residual ore body and ore body which is previously reported was confirmed. In addition, another highly probable region of iron ore bodies was estimated deeper depth in study area through integrated modeling.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.507-513
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• 2006

In this paper, we propose an improved image encryption and fault-tolerance decryption method using phase wrapping and phase encoding in the frequency domain. To generate an encrypted image, an encrypting key which denotes the product of a phase-encoded virtual image, not an original image, and a random phase image is zero-padded and Fourier transformed and its real-valued data is phase-encoded. The decryption process is simply performed by performing the inverse Fourier transform for multiplication of the encrypted key with the decrypting key, made of the proposed phase wrapping method, in the output plane with a spatial filter. This process has the advantages of solving optical alignment and pixel-to-pixel mapping problems. The proposed method using the virtual image, which does not contain any information from the original image, prevents the possibility of counterfeiting from unauthorized people and also can be used as a current spatial light modulator technology by phase encoding of the real-valued data. Computer simulations show the validity of the encryption scheme and the robustness to noise of the encrypted key or the decryption key in the proposed technique.

• Polymer(Korea)
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• v.39 no.2
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• pp.317-322
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• 2015

Salinity gradient power is a system which sustainably generates electricity for 24 hrs, if the system is constructed at a certain place where both seawater and river water are consistently pumped. Since power is critically determined by the water flux and the salt rejection, a membrane of water-semipermeable aquaporin protein in cell membranes was studied for pressure-retarded osmosis. NaCl was used as a salt, and $NaNO_3$ was used as a candidate to check the ion selectivity. The water flux of biomimetic aquaporin membranes was negligible at a concentration below 2M. Also, there is no remarkable dependence of water flux and ion selectivity on concentrations higher than 3M. Therefore, the biomimetic aquaporin membrane could not be applied into pressure-retarded osmosis; however, if a membrane could overcome the current limitations, the properties shown by natural cells could be accomplished.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.3
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• pp.213-217
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• 2006

We evaluated the potential of major components of Phellodendri cortex to inhibit the activities of CYP2D6 and p-glycoprotein. The abilities of berberine, palmatine, limonin, and rutaecarpine to inhibit CYP2D6-mediated dextromethorphan O-demethylation and calcein AM accumulation were tested using human liver microsomes and L-MDR1 cell, respectively. Berberine strongly inhibited CYP2D6 isoform activity, whereas limonin and reuaecarpine did not. The $IC_{50}$ value of berberine was reduced after preincubation with microsomes in the presence of NADPH generating system, suggesting that berberine is a mechanism based inhibitor. In addition, all chemicals tested, didn't show inhibitory effect on p-glycoprotein activity. These results suggest that berberine has potential to inhibit CYP2D6 activity in vitro. Therefore, in vivo studies investigating the interactions between berberine and CYP2D6 substrates are necessary to determine whether inhibition of CYP2D6 activity by berberine is clinically relevant.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.3
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• pp.219-226
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• 2011

The Echinacea, which has been commonly known as a species of composite herb of dicotyledonous plant, has been used in native American traditional medicine for the treatment of diseases like colds or other infections in North America. We artificially cultured the adventitious roots of Echinacea angustifolia using the bioreactor culture system from Echinacea angustifolia and evaluated the efficacy as a cosmetic ingredient for skin care. Several studies previously have reported neogenesis, wound healing and inflammatory inhibition effect of Echinacea angustifolia but other efficacies were not well known. In the present study, we investigated the cosmetic efficacy to know applicable value of adventitious roots cultured from Echinacea angustifolia as a cosmetic ingredient. The adventitious roots extract of Echinacea angustifolia has superior anti-oxidant effect and matrix metalloproteinase-2 inhibitory effect, compared to natural Echinacea angustifolia. These results indicate that the adventitious roots extract cultured from Echinacea angustifolia presents a new possibility of being applicable to skin care and anti-wrinkle products as a cosmetic ingredient.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.91-105
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• 2013

This study performed an assessment of wave power potential in the Kangwon and Dongnam regions encompassing the East Sea and part of South Sea. Annual electricity production and economic effects of 28 wave energy converters with 750kW capacity were analyzed using significant wave height and peak wave period data(created from the NOAA's NWW3 model) and InVEST software(developed by Stanford University and University of Minnesota). Annual electricity production was estimated to be up to 1,207MWh/year and at least 163MWh/year. The spatial pattern of annual electricity production showed that the sea far from land has higher wave power potential than the sea near coast. The net present value(NPV) of 28 wave energy converters was calculated by considering an operation period of 25 years. When assuming that the electricity produced from wave energy converters is transferred to onshore power plants through underwater cables, the NPV was estimated to be up to 5,883USD(6,600,000KRW) and at least -63,494USD(-71,000,000KRW). In contrast, the NPV increased up to 28,095 USD(31,600,000KRW) when assuming that the electricity is utilized in the Ulleungdo and Dokdo. In addition, it was found that the break-even line of NPV in the East Sea becomes closer towards the land according to the increment of electricity price. The NPV of wave energy converters near the Ulleungdo and Dokdo will be 88,158 USD(99,000,000KRW) if the increment of electricity price is 100KRW.

• Composites Research
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• v.24 no.6
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• pp.56-63
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• 2011

The objective of this study is to investigate appropriate bonding methods of solar cells in order to apply solar cells, which have been receiving particular attention as a renewable energy due to fossil energy depletion and environment issues, to composite structures. Back-contact solar cells with approximately 24.2% energy conversion efficiency were used in this study. Since silicon-based solar cells are mechanically fragile, the secondary-bonding methods using adhesive were examined in this study. The experiment was conducted with three kinds of bonding materials such as EVA film, Resin film and elastic adhesive. The performance of solar cells for three types of adhesives under mechanical loading on test specimens is conducted. In addition, the measuring equipment was designed to evaluate the performance of the solar cells under mechanical loading in real time and the fracture characteristics depending on bonding materials were evaluated. The reason decreasing solar cells efficiency were analyzed and considered by Fractography. The results show that the solar cell performance is largely affected by bonding techniques. Moreover, the bonding method using elastic adhesive shows best solar cell efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.7
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• pp.1399-1404
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• 2004

The development of computer technology and the advancement of the technology of information and communications spread the technology of multimedia and increased the use of multimedia data with large capacity. Users can grasp the overall video data and they are able to play wanted video back. To grasp the overall video data it is necessary to offer the list of summarized video data information. In order to search video efficiently an index process of video data is essential and it is also indispensable skill. Therefore, this thesis suggested the effective method about the cut detection of frames which will become a basis of an index based on contents of video image data. This suggested method was detected as the unchanging pixel rotor intelligence value, classified into diagonal direction. Pixel value of color detected in each frame of video data is stored as A(i, i) matrix - i is the number of frames, i is an image height of frame. By using the stored pixel value as the method of UE(Mean Square Error) I calculated a specified value difference between frames and detected cut quickly and exactly in case it is bigger than threshold value set in advance. To carry out an experiment on the cut detection of lames comprehensively, 1 experimented on many kinds of video, analyzing and comparing efficiency of the cut detection system.

• Korean Journal of Construction Engineering and Management
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• v.17 no.5
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• pp.71-77
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• 2016

Solar energy is a viable source to replace fossil fuels. However, challenges associated with site selection for solar panel installation inhibit the uptake of solar energy systems. Expressway slopes offer a potentially attractive alternative for solar panel installation for the following reasons: expressway slopes are vacant public sites, they are abundant (about 4,193km in South Korea), and they are linear in nature. Traditoinally when selecting sites for solar systems conventional surveying methods are employed. Unfortunately, these methods can be dangerous, time consuming, and labor intensive. To overcome these limitations of conventional site selection methodologies, we propose an automated approach using numerical maps. First, contour and expressway polylines are extracted separately from numeric maps. The extracted contour lines are then converted into a digital terrain model; this is used to calculate aspect and slope information. Next, the extracted expressway lines are projected onto a binary image and refined to recover the disconnections, and then applied to create a buffer zone to narrow the search space. Finally, all data sets are overlaid to identify candidate sites for solar panel systems and are visually verified through comparisons with aerial photos.