• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.4
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• pp.405-412
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• 2012

In the past, a very popular way to reduce the corrosion rate of zinc was the use of chemical conversion layers based on $Cr^{+6}$. However, the use of chromium salts is now restricted because of environmental protection legislation. Previous research investigated the optimum corrosion resistance of galvanized steel treated with an organic/inorganic solution containing Si. The result showed that the optimum corrosion resistance occurred by heat treatment of $190^{\circ}C$ in 5 min. In this study, one organic and three hybrid organic/inorganic coating solutions were applied to cold-rolled (CR) carbon steel. The coatings were then evaluated for corrosion resistance under a salt spray test. The coating solutions examined in this study consisted of urethane-only, urethane-Si, urethane-Si-Ti, and urethane-Si-Ti-epoxy. The results of the 7 h salt spray test showed that the urethane-Si-Ti and urethane-Si-Ti-epoxy coating solutions had superior corrosion resistance on CR steel.

• Environmental and Resource Economics Review
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• v.20 no.2
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• pp.167-198
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• 2011

The Korean government recently announced greenhouse gases (GHG) emissions reduction target as 30% of 2020 business as usual (BAU) emission projection. As carbon emissions trading is widely used to achieve reductions in the emissions of pollutants, this study deals with the sectoral allocation of initial carbon emission permits in Korea. This research tests the effectiveness of a variety of allocation rules based on the bankruptcy problem in cooperative game theory and hybrid input-output tables which combines environmental statistics with input-output tables. The impact of initial emission permits allocation on economic growth is also analyzed through green growth accounting. According to the analysis result, annual GDP growth rate of Korea is expected to be 4.03%, 4.23%, and 3.67% under Proportional, Constrained Equal Awards, and Constrained Equal Losses rules, respectively. These rates are approximately from 0.69% points to 0.13% points lower than the growth rate of 4.36% without compulsory $CO_2$ reduction. Thus, CEA rule is the most favorable in terms of GDP growth. This study confirms the importance of industry level study on the carbon reduction plan and initial carbon emission permits should reflect the characteristic of each industry.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1089-1097
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• 2002

In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.

• Journal of Digital Contents Society
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• v.16 no.3
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• pp.389-395
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• 2015

Digital image provides many conveniences at the internet environment recently. A great number of applications, like Digital Library, Stock Image, Personal Image and Important Information, require the use of digital image. However it has fatal defect which is easy to be modified because digital image is only electronic file. Numerous digital image forgeries have become a serious problem due to the sophistication and accessibility of image editing software. Copy-Move forgery is the simplest type of forgery that involves copying portion of an image and paste it on different location within the image. There are many approaches to detect Copy-Move forgery, but all of them have their own limitations. In this paper, visual and invisible feature based forgery detection techniques are tested and analyzed. The analysis shows that pros and cons of these two techniques compensate each other. Therefore, a hybrid of visual based and invisible feature based forgery detection that combine the merits of both techniques is proposed. The experimental results show that the proposed algorithm has enhanced performance compared to individual techniques. Moreover, it provides more information about the forgery, like identifying copy and duplicate regions.

• Polymer(Korea)
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• v.35 no.1
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• pp.7-12
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• 2011

Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable synthetic polymer with acceptable mechanical strength and well-controlled degradation rate. Also, it can be easily fabricated into many shapes. Silk fibroin contains powerful bioactive molecules. We fabricated natural/synthetic hybrid films using 0, 10, 20, 40 and 80 wt% of silk fibroin. Schwann cells (SCs) were seeded on PLGA/silk fibroin hybrid films and confirmed the effects of adhesion and proliferation on SCs according to the content of silk fibroin. In this study, we confirmed PLGA/silk fibroin hybrid film containing 40% and 80% of silk fibroin interrupted adhesion and proliferation of SCs. Films containing 10% and 20% of silk, however, provided suitable environment for growth and proliferation of SCs. These results suggest that silk fibroin provides suitables surface to neural cells and its proper content provides proper culture conditions to improve cell adhesion and proliferation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.947-954
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• 2009

This paper proposed a new balanced power amplifier using the reflected input of conventional balanced power amplifiers composed of branch line hybrid coupler. In general, the single-ended amplifier in balanced amplifiers does not have the perfect matching, so the reflected input power, in other words the leakage power, is terminated conventionally at the isolation port of hybrid coupler. However in this work, the leakage power is injected into the auxiliary amplifier, and its output power is combined to the output power of balanced amplifier. Therefore output power, efficiency, and 2-tone IMD3 performances of the proposed balanced amplifier are highly improved compared to the conventional balanced amplifier. For the verification of the proposed balanced amplifier, a conventional balanced amplifier and the proposed balanced amplifier are designed, fabricated and measured, and the measured results are compared. The proposed balanced amplifier shows the improvement in the output power(Pout), power added efficiency (PAE), and 2-tone IMD3 by 3dB, 5.2%, and $5{\sim}10dBc$, respectively, from the measurement.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.305-313
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• 2012

Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.

• Journal of Adhesion and Interface
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• v.18 no.1
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• pp.13-24
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• 2017

In this study, nanoparticles which encapsulated hydrophobic antimicrobial compounds with 50wt% of payload and 70%of solid content were prepared. These nanoparticles could be dispersed at water as well as various medium. Water dispersible organic-inorganic (O-I) hybrid nanoparticles were first prepared using alkoxysilane-functionalized amphiphilic polymer precursors through a conventional sol-gel process. Hydrophobic antimicrobial compound, Eugenol encapsulated nanoparticles were prepared using these O-I hybrid nanoparticles through a new nanoprecipitation process. The effect of various preparation on the size of nanoparticles, amount of payload, antimicrobial activity, and release rate of encapsulated compounds was investigated. All eugenol-encapsulated O-I nanoparticles regardless of preparation condition showed the same minimal inhibitory concentration (MIC) (50mg/ml) and 99% of antimicrobial activity for every strain. Their antimicrobial activity could maintain longer than two weeks. Especially, eugenol-encapsulated O-I nanoparticles prepared using tetraethoxysilane (TEOS) exhibited the highest payload (50wt%) and the lowest release rate which was owing to higher inorganic content in the O-I nanoparticles. And these O-I nanoparticles dispersed in hexanediol (HD) showed the highest antimicrobial activity and solid content (70wt%) because HD acted as a solvent as well as a antimicrobial agent.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.315-321
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• 1999

Metal matrix composites have been extensively studied because of their excellent characteristics for structural application. $Al_2O_3$ and SiC have been used as a common reinforcement owing to their good mechanical properties. However the manufacturing cost of these ceramic reinforcement is expensive, so the use of the composites has been restricted to special purposes. In this study, we tested the application possibility as a reinforcement of $Al_2O_3$-TiC powder synthesized by SHS(Self-propagating High-temperature Synthesis) process to Al alloy matrix composite. Also, $Al_2O_3$ short fibers were added with the synthesized powders in order to apply to the Al matrix hybrid composites. Squeeze infiltration casting process was used to make the composite with 25vol% of reinforcement. Microstructure and crystal structure were examined by SEM, OM and XRD, also the mechanical properties were studied by the compressive test and wear test.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.455-459
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• 2003

In the great motive power which promotes the Game of future to develop. three main factors focus on 3D Graphics, Network and Virtual Reality. the Network technique as necessary elemental technique in Next-generation on-line game is being researched largely. However, from viewing the features of on-line game, if many users meet in same server, it not only causes heavy load to the server and brings inconvenience to the users, but also increases expense to the service provider and creates a problem which is to put up server or not. A proposal is going to do hybrid distributed system a client hardly depends on server for this paper, and to be able to enjoy a network game through information alternating current between clients. depended on the existing server, and the most message processing did a design in order to achieve between clients. A design way to propose is as follows. Primarily it was done in order proposed a message grade anger process way, and to be able to manage server or a client according to importance of message, and, with the second, did a Client-Server method and a Pear-to-Pear method at the same time, and a chase did efficiency. Third is going to propose other problem solving way by message grade anger in multi-anger and a security section of a message cue.