• 융복합기술연구소 논문집
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• 제4권1호
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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.

• 대한조선학회논문집
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• 제45권6호
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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.

• 한국산업정보학회논문지
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• 제17권2호
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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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• 제10권4호
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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.

• 신재생에너지
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• 제6권2호
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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.

• 패션비즈니스
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• 제27권6호
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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.

• 한국콘텐츠학회논문지
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• 제17권4호
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• pp.1-11
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• 2017

신재생에너지에 대한 관심이 증가하고 있지만 부정적인 여론으로 인해 초소수력 발전소 개발이 부진한 실정이다. 그러나 다른 신재생에너지에 비해 에너지 변환효율이 높고 이산화탄소를 배출하지 않아 대체에너지로써 개발 및 확대에 대한 관심이 필요하다. 이에 본 연구는 이클립스(Eclipse)를 이용하여 초소수력 발전량을 가시화하는 지도를 담는 애플리케이션을 개발하였다. 이를 통해 먼저 대상지점을 선택하고 미 공병단에서 제공하는 HEC-HMS으로 산출한 확률 설계유량으로 발전용량을 산정한 후 경제성 분석을 수행할 수 있다. 시범지역으로 강수량이 풍부한 강원도 영월군을 선정한 후, 국가수자원관리종합정보에서 제공하는 기초자료를 이용하여 초소수력 발전 잠재량 분석을 수행하였다. 본 연구 결과로 대상지점의 예상발전량, 연간전기생산량, 경제성분석 등을 단시간에 평가할 수 있고, 전국을 대상으로 잠재되어 있는 초소수력 발전 가능지역을 선별하는데 활용될 것으로 기대된다. 또한 간편하게 발전 가능지역을 선별할 수 있기 때문에 초기 투자비용을 줄일 수 있을 것으로 판단된다.

• 대한조선학회논문집
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• 제48권2호
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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.

• 한국항공우주학회지
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• 제33권9호
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• pp.56-65
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• 2005

시간유한요소법은 시간영역을 고정시키고 행렬 미분방정식 형태의 공간전파 관계식을 풂으로써 시간과 공간에 대한 동적 해석을 수행하는 방법이다. 이 방법은 공간이산화 유한요소법이나 시/공간 동시이산화 유한요소법에 비해 공간에 관한 자유도가 발생하는 것이 두드러진 특징으로, 이를 이용하여 분포형 구동기의 공간에 따른 특성을 최적화하는 데에 효율적으로 사용될 수 있다. 본 논문에서는 임의의 초기조건을 반영할 수 있도록 구성된 상태변수 벡터를 이용하여 구조물을 시간영역에서 이산화하고, 공간영역에서 전파관계식 및 경계조건을 이용하여 공간전파 관계식을 형성하였다. 이 때 구동기의 공간에 따른 형상 분포는 설계되어야 할 변수의 함수이고, 시간반응은 형상함수를 이용하여 이산화 하였다. 포텐셜 에너지 및 운동에너지를 구조물의 변위제어에 적절한 최적의 성능지수로 설정하고, 이를 최소화하도록 미지의 함수인 구동기의 분포형상을 구하였다. 일반적으로 구조물은 임의의 초기조건에서 외란을 받게 되나, 본 연구에서는 구현가능한 제어법칙을 이용하여 최종시간에서 안정화(rest) 조건을 만족한다고 가정하였다. 구동기 분포형상 최적화를 위해 상태/준상태 방정식을 유도하였다. 서브행렬 재형상화와 시/공간 경계조건을 통해 상태변수와 준상태변수에 대한 Ricatti 미분방정식을 유도하였다. 이를 통해 구동기 분포형상 최적화를 구현하였으며, 수치 시뮬레이션을 통해 적절한 구동기의 분포형상 최적화를 수행할 수 있음을 보였다.