• Journal of Institute of Convergence Technology
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• v.4 no.1
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• pp.15-20
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• 2014

Recently, the development of renewable energy sources in Korea has been needed due to climate change. One of powerful alternative energy resources to mitigate emission is to switch conventional fuels to renewable energy, such as bioenergy. In this study, current status of bioenergy conversion technology and its supply in Korea was investigate. Based on theoretical, technical and realizable potential of biomass in Korea, the amount of reduction of green house gases was estimated. The results shown that the contribution of biomass on 2020 reduction target of green house gases emission in power generation was $513,000\;tCO_2/yr$ and utilization ratio of technical potential of biomass was 6.4%. For the effective supply of bioenergy in Korea, more exact estimation of realizable potential of biomass in Korea and stable supply sources are needed.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.631-636
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• 2008

In this paper, numerical analysis based on the RANS equation and the Realizable ${\kappa}-{\varepsilon}$ turbulence model is carried out for flows around an axisymmetric body at three Reynolds numbers($1.22{\times}10^7$, $1.0{\times}10^8$, $1.5{\times}10^8$) and the numerical results are compared with experiments data. Computed velocity distributions agree well with experiments as the Reynolds number increases. Pressure distributions agree well with the results of the potential flow except the tail region but differ from experiments for the parallel middle body as well as tail region. Pressure gradients show a good agreement with those of potential flow and experiment except the tail region. Friction coefficients show that the numerical results generally are lower than the experimental results estimated from the measured velocity. The difference of friction coefficients between the calculation and the experiment increases with growing of a boundary layer.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.2
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• pp.29-32
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• 2012

Computer generated holography (CGH) is technology for generating holograms of synthetic, three dimensional (3D) objects which may not exist in the physical world. The process, however, requires heavy amount of computation as the resolution of a hologram is significantly higher than that of a typical optical image. This paper reviews four modern techniques for fast generation of digital Fresnel holograms which are important in the development of holographic video systems. The methods that will be described include the virtual window, sub-line, wavefront recording plane (WRP), and the interpolative WRP schemes. These works share the common objective to generate digital Fresnel hologram at a speed that is close to the video frame rate, and with complexity which is realizable with affordable computing and reconfigurable hardware devices. The author will present the principles and realization of these works, as well as some potential area of research in digital holography.

• Journal of Ship and Ocean Technology
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• v.10 no.4
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• pp.1-11
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• 2006

The finite volume based multi-block RANS code, WAVIS developed at MOERI is applied to the numerical self-propulsion test. WAVIS uses the cell-centered finite volume method for discretization of the governing equations. The realizable $k-{\epsilon}$ turbulence model with a wall function is employed for the turbulence closure. The free surface is captured with the two-phase level set method and body forces are used to model the effects of a propeller without resolving the detail blade flow. The propeller forces are obtained using an unsteady lifting surface method based on potential flow theory. The numerical procedure followed the self-propulsion model experiment based on the 1978 ITTC performance prediction method. The self-propulsion point is obtained iteratively through balancing the propeller thrust, the ship hull resistance and towing force that is correction for Reynolds number difference between the model and full scale. The unsteady lifting surface code is also iterated until the propeller induced velocity is converged in order to obtain the propeller force. The self-propulsion characteristics such as thrust deduction, wake fraction, propeller efficiency, and hull efficiency are compared with the experimental data of the practical container ship. The present paper shows that hybrid RANS and potential flow based numerical method is promising to predict the self-propulsion parameters of practical ships as a useful tool for the hull form and propeller design.

• New & Renewable Energy
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• v.6 no.2
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• pp.33-39
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• 2010

The objective of this study is to present a basis for the evaluation on the renewable energy dissemination program in Korea applying the outcome evaluation, one of the five types of evaluation methods of EERE, DOE, and the effectiveness indicator, which is suggested by IEA, OECD. The outcome evaluation quantifies achievements of program outputs and outcomes against planned time frame. We analyze the correlation coefficients between cumulative expenditure on the renewable energy dissemination program and each renewable energy deployment and the unit installation cost of several dissemination programs for the outcome evaluation. Meanwhile, the effectiveness indicator is calculated by dividing the additional renewable energy deployment achieved in a given year by the remaining mid-term realizable potential to 2020 in each source of renewable energy. The results show that correlation coefficients between cumulative expenditure and each renewable energy deployment are significantly positive during the implementation period of each deployment program. And photovoltaic energy, bio energy, and wind power energy show high effectiveness indicator.

• Journal of Fashion Business
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• v.27 no.6
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• pp.85-98
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• 2023

People nowadays must adapt to and live with a new software idea known as the "Metaverse" due to an inevitable shift in lifestyle brought on by pandemic effects. However, since the Covid-19 became an endemic, the enthusiasm towards the metaverse platform decreased significantly. But the potential of the metaverse remains a significant area of interest. Experiencing developments in technology can serve as a substantial lesson for the future. Notable metaverse platforms in the Republic of Korea so far include domestic companies such as ZEPETO, IFLAND, ZEP, and the Singaporean company BONDEE. Various metaverse platforms are being launched, and various studies are proceeding. However, there is still value in research specifically analyzed in the field of fashion. In this study, by comparing and analyzing the fashion design on the metaverse platforms ZEPETO, IFLAND, ZEP, and BONDEE, which are well-known in the Republic of Korea, metaverse fashion can be categorized into three types: 'Daily Type,' 'Costume Type,' and 'Unrealistic Type.' Analyzing these types revealed three characteristics of metaverse fashion design: realizable, playfulness, and expressiveness. This study holds significance in gaining foresight and a consistent interest in metaverse fashion by comparing and analyzing the fashion designs of well-known metaverse platforms in Korea.

• The Journal of the Korea Contents Association
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• v.17 no.4
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• pp.1-11
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• 2017

Interest in all kinds of renewable energies has been highly increased while the micro-small-hydro power(MSHP) development has shown relatively slowly growth because of the negative public recognition about dam site development. It is, however, announced that the micro-SHP shows higher energy conversion efficiency compared to other renewable energies and does not emit any carbon dioxide. Thus, it is concerned about the development and application of micro-SHP as an alternative energy. In this study, the application for Android was exploited with Eclipse to visualize readily the potential realizable amount of hydropower by micro-SHP. With this application, we can select the region from the map, obtain the design discharge of the selected site was calculated with HEC-HMS, presented by U.S. Army of Corp. and perform the simply economic analysis in sequence. Yeongwol in Gangwon-do Province, Korea was chosen as the target area since historically abundant precipitation was found and it is possible to obtain fundamental data from WAMIS. Results from this study could be expanded the whole region of Korea. Also, the initial investment cost would be reduced if the location for micro-SHP would be determined properly, because this application can help us easily select and examine the potential micro-SHP sites without on-the-spot visit.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.147-157
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• 2011

A RANS(Reynolds averaged Navier-Stokes) based numerical method is developed for the evaluation of ship resistance and self-propulsion performances. In the usability aspect of CFD for the hull form design, the field grid around practical hull forms is generated by solving a grid Poisson equation based on the hull surface grid generated from station offsets and centerline profile. A body force technique is introduced to model the effects of the propeller in which the propeller loads are obtained from potential flow analysis using an unsteady lifting surface method. The free surface is captured by using a two-phase level-set method and the realizable $k-{\varepsilon}$ model is used for turbulence closure. The hull attitude in vertical plane, i.e., trim and sinkage, is calculated by using a quasi-steady method and then considered in the computation by translating and rotating the grid system according to the values. For the validation of the proposed method, the numerical results of resistance tests for KCS, KLNG, and KVLCC1 and of self-propulsion test for KCS are compared with experimental data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.56-65
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• 2005

A dynamic analysis method that freezes a time domain by discretization and solves the spatial propagation equation has a unique feature that provides a degree of freedom on spatial domain compared with the space discretization or space-time discretization finite element method. Using this feature, the time finite element analysis can be effectively applied to optimize the spatial characteristics of distributed type actuators. In this research, the time domain finite element method was used to discretize the model. A state variable vector was used in the discretization to include arbitrary initial conditions. A performance index was proposed on spatial domain to consider both potential and vibrational energy, so that the resulting shape of the distributed actuator was optimized for dynamic control of the structure. It is assumed that the structure satisfies the final rest condition using the realizable control scheme although the initial disturbance can affect the system response. Both equations on states and costates were derived based on the selected performance index and structural model. Ricatti matrix differential equations on state and costate variables were derived by the reconfiguration of the sub-matrices and application of time/space boundary conditions, and finally optimal actuator distribution was obtained. Numerical simulation results validated the proposed actuator shape optimization scheme.