• Journal of Advanced Marine Engineering and Technology
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• v.37 no.3
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• pp.266-273
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• 2013

With the worldwide trend of controlling the utilization of fossil fuels inducing global climate change, many efforts will have to be made on securing a sustainable energy supply. Tidal current is a concentrated form of gravitational energy, its resource is significant, but limited locations. To effectively capture tidal current energy from the sea, a group of tidal turbines should be formed and positioned with optimal size and spacing for absorbing from multiple points. Thus, the flow field including turbines becomes a huge domain, a so-called tidal farm. It can be very convenient technically and economically if a whole turbine farm is simulated by means of actuator disc thoery. So, the analysis method using actuator discs coupled with a solution of Reynolds Averaged Navier-Stokes (RANS) equations is adopted for actual tidal turbines. Actuator discs have regions where similar forces imposed by actual turbines are applied to a flow. As working in group formation, turbines naturally have interaction effects on one another. Therefore, the present paper investigate the evaluation on the operating performance of tidal farm in terms of the mutual influence among turbine units with various lateral and longitudinal spacing. Authors expect that results of the present study contribute to the development of tidal farm for the future potential energy.

• Journal of Energy Engineering
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• v.11 no.2
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• pp.160-165
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• 2002

The heavy-duty LPG-fueled single cylinder engine was designed and developed as a fundamental equipment for analyzing combustion processes and emission performances. The cylinder head and the piston crown were modified to fire the LPG in the engine. The flywheel was also fabricated to minimize the vibration of the single cylinder engine. The size of bore and stroke of the tested engine are 130 mm and 140 mm, respectively. Compression ratios were varied 8 to 9 with different piston crown shapes. The developed single cylinder engine operates at 1,000 rpm for this work. The major conclusions of this work are; (1) the power of the developed engine was peaked at the condition of equivalence ratio 1.0 at three different compression ratios; (2) the power is slightly increased with the increase of compression ratio; (3) the optimum ignition timing is retarded with the increase of compression ratio ranged 2 to 10 crank angle.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.795-800
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• 1994

The detergencies of these new functional anionic surfactants, sodium monoglycerol ${\alpha}$-sulfonated alkanoates, were investigated and compared with those of two commercial surfactants, that is, sodium ${\alpha}$-sulfonated alkanoic acid methyl ester and sodium alkyl benzene sulfonate. According to the variation of the hydrophobic alkyl chain length, the order of detergency was shown to be $C_{16}$>$C_{18}$>$C_{14}$>$C_{12}$. From the comparision experiment for the detergency and the various fundamental properties of two other surfactants, it was found that sodium monoglycerol ${\alpha}$-sulfonated hexadecanonate has the most outstanding characteristics of detergency. Possibly this result shows light on its industrial application as a nonpolluting detergent.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.172-178
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• 1990

To predict the qualitative performance characteristics of Stirling Engines, an analytical approach to the Ideal Adiabatic Model set up by Urieli et al. has been treated. First, volume variations of both the expansion and the compression cylinders are approximated to piecewise linear function of the crank angle, which make it possible to specify the mass flow direction of each cylinder a priori to solve a set of basic equation. In consequences, an engine cycle can be considered as a combination of 4-type fundamental process. For each process, pressure is obtained as a solution of the algebraic equation. Application of the cyclic steady condition to the whole cycle completes the analysis. Further investigations result in analytical expressions for cyclic heat and work in terms of dependent variables determined from the pressure. The results are expected useful in establishing the preliminary design conditions of Stirling Engines.

• Journal of Fashion Business
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• v.19 no.6
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• pp.28-41
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• 2015

Properties of textile fabrics influence the appearance, aesthetics, and performance of garment. Drape and related properties of fabrics affect profoundly the static and dynamic appearance during wearer's movement. The three dimensional shape of the folded structure often deforms with time or with subtle vibration around the fabric specimen during the drape measurement. Due to the uneven and complex nature of fabrics, the overall shape of the fabric specimen on the drape tester often becomes unstable. There is a need to understand the fundamental mechanisms of how draping may generate pleasing forms. Two drape test methods, conventional Cusick drape test, and in-built drape tester, based on a depth camera, are compared. Fabric specimens including cotton, linen, silk, wool, polyester, and rayon are investigated for the fabric drape and other physical/mechanical parameters. Drape coefficient values of fabric specimens are compared based on the final drape images, together with the intermediate 3D drape images of the specimens during elevation process of the drape tester equipped with a stepper motor system. The correlation coefficient between the data based on the two methods is reasonably high. Another advantage from the depth camera system is that it allows further analysis of three-dimensional information regarding the fabric drape shape, including the shape of nodes or crest and trough.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.52-56
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• 2001

A fundamental study on the cooling apparatus inshore fishing boat and its operation characteristics in sea water cooling system were performed experimentally. The circumstance is giving the blow against fisherman with incoming-decreasing and the difficulty of crew's supply and demand and management. In addition, the depression of the external situation such as the plan of EEZ(Exclusive Economic Zone) proclaim is forcing them into improving their fishing condition. By this international and domestic surrounding, the development of a cooling apparatus inshore fishing boat is demanded sincerely. We investigated load characteristics as the pilot plant operation characteristics estimation which is based on the development of cooling system and optimum cooling apparatus inshore fishing boat. These results provide useful informations which are applicable to an actual design and show the possibility of application to other fields.

• Current Industrial and Technological Trends in Aerospace
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• v.7 no.1
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• pp.56-67
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• 2009

From 1990s, the lunar exploration programs, suspended over 20 years after the project Apollo's first successful human landing on the Moon in 1969, have been restarted according to a revived interest in Moon. In recent, several nations progress their own lunar exploration program successfully. In this report, to investigate the technical trends of the onboard propulsion system for the lunar orbiter, technical features related to the performance of the propulsion system of the lunar orbiters developed since 1990 are surveyed. In the future, it is expected that this technical report can provide a fundamental guideline for selecting a proper type of the onboard propulsion system for the domestic lunar orbiter.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1057-1058
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• 2011

This paper deals with finding the optimal ratio of height and length of Single-Sided Linear Induction Motors (SLIM) using Finite Element Method (FEM) for magnetic field analysis coupled with optimal design methodology. For effective analysis, FEM is conducted in time harmonic field which provides steady state performance with the fundamental components of voltage and current. The ratio of height to length providing the required output power is obtained by Response Surface Methodology (RSM) and optimal values are presented by the variation in output power. When output power is small, the ratio is high and as the power increases, the ratio shows a converged value. Considering the general application of linear motors, using a small ratio can be limiting, however, the shape ratio for maximum thrust can be identified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1157-1162
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• 2001

This paper deals with inspect algorithm using visual system. One of the major problems that arise during polymer production is the estimation of the noise of the color product.(bad pallets) An erroneous output can cause a lot of losses (production and financial losses). Therefore new methods for real-time inspection of the noise are demanded. For this reason, we have presented a development of vision system algorithm for the defect inspection of PE color pallets. First of all, in order to detect the edge of object, the differential filter is used. And we apply to the labelling algorithm for feature extraction. This algorithm is designed for the defect inspection of pallets. The labelling algorithm permits to separate all of the connected components appearing on the pallets. Labelling the connected regions of a image is a fundamental computation in image analysis and machine vision, with a large number of application. Also, we suggested vision processing program in window environment. Simulations and experimental results demonstrate the performance of the proposal algorithm.

• Journal of Navigation and Port Research
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• v.29 no.10 s.106
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• pp.827-832
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• 2005

In this paper, as a fundamental study of ship collision avoidance supporting system in close quarters situation, we propose ship collision avoidance support model for decreasing ship collision accidents those have occurred due to navigator's unsuitable maneuvering in close encounter. This model will effectively support maneuvering for collision avoidance through displaying the feasible area and the method of collision avoidance using own ship's turning characteristic about action of target ship's keeping course and velocity.