• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.743-746
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• 2004

This study is generally purposed to develop a mobile augmentative and alternative communication system (hereinafter referred to as 'a mobile AAC system'). Also the device is aimed as a mobile AAC system for helping communication of persons who suffer from speech disorders in a free and convenient manner. One thing firstly considered for a successful AAC system is selection of vocabularies. For this purpose, the above researchers collected utterances in actual situations to select vocabularies of higher frequencies. For generation of sentences by maximizing the use of limited space in the AAC system, this study specifically presents a method of predicting predictions. This method includes selecting vocabulary and classifying it by domains so as to meet the characteristics of the mobile AAC communication, using a noun thesaurus for semantic analysis, and building a sub-category dictionary. Predicting predicates by selecting symbols in accordance with this method is tested and the utility thereof is confirmed.

• IEIE Transactions on Smart Processing and Computing
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• 제2권5호
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• pp.255-265
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• 2013

3DTV is expected to be a promising next-generation broadcasting service. On the other hand, the visual discomfort/fatigue problems caused by viewing 3D videos have become an important issue. This paper proposes a perceptual quality assessment metric for a stereoscopic video (SV-PQAM). To model the SV-PQAM, this paper presents the following features: temporal variance, disparity variation in intra-frames, disparity variation in inter-frames and disparity distribution of frame boundary areas, which affect the human perception of depth and visual discomfort for stereoscopic views. The four features were combined into the SV-PQAM, which then becomes a no-reference stereoscopic video quality perception model, as an objective quality assessment metric. The proposed SV-PQAM does not require a depth map but instead uses the disparity information by a simple estimation. The model parameters were estimated based on linear regression from the mean score opinion values obtained from the subjective perception quality assessments. The experimental results showed that the proposed SV-PQAM exhibits high consistency with subjective perception quality assessment results in terms of the Pearson correlation coefficient value of 0.808, and the prediction performance exhibited good consistency with a zero outlier ratio value.

• Korean Chemical Engineering Research
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• 제49권3호
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• pp.361-366
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• 2011

몬테칼로 시뮬레이션 방법을 사용하여 유기화합물의 열역학적 물성을 예측하는 새로운 분자 시뮬레이션 소프트웨어를 개발하였다. 분자 구조, 분자간 포텐셜 에너지 함수와 엄밀한 통계역학적 원리로부터 많은 분자들을 포함한 계의 거동에 대한 확률 분포를 구하고 거시적인 계의 열역학적 물성을 계산한다. 본 연구에서 개발된 소프트웨어 cheMC는 윈도우즈 플랫폼에 기반하여 사용자 접근성이 좋고, 가시화 도구 및 차트 생성 기능 등 직관적인 인터페이스로 시뮬레이션 관리가 쉽다. 분자 시뮬레이션은 기존의 상태 방정식을 사용한 열역학 물성 연구를 보완하고, 향후 그 역할이 점점 더 커질 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1379-1387
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• 2017

This paper presents a comparison of homogenization techniques implemented in the APOLLO3 platform for transport core calculations: standard scalar flux weighting and new flux-moment homogenization, in different combinations with (or without) leakage models. Besides the historical B1-homogeneous model, a new B-heterogeneous one has indeed been implemented recently in the two/three-dimensional-transport solver using the method of characteristics. First analyses have been performed on a very simple Sodium Fast Reactor core with a regular hexagonal lattice. They show that using the heterogeneous leakage model in association with flux-moment homogenization strongly improves the prediction of $k_{eff}$ and void reactivity effects. These good results are confirmed when the application is done to the fissile assemblies of the more complex CFV (Low Void Effect) core of the ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) project of sodium-cooled fast breeder reactor (Generation IV).

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.367-377
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• 2015

Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK$^{(R)}$) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK$^{(R)}$ Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.

• Current Photovoltaic Research
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• 제7권4호
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• pp.121-124
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• 2019

In this research, the concept of a salt farm parallel solar power system, which produce salt and electricity at the same site, is proposed for the first time in the world. The concept is that large waterproof plates made by interconnected solar modules are installed at the bottom of the salt farm. The pilot system was successfully installed at a sea shore, and verified its feasibility as a solar power plant. For deeper understanding, simulations for power prediction of the system were carried out and compared with the field test results. The power generation of the salt farm parallel system is comparable to conventional solar power plants. The cooling effect by sea water contributes more to the increase in the crystalline silicon photovoltaic module performance than the absorption loss due to sea water by maintaining certain height above the module.

• 대한기계학회논문집B
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• 제27권12호
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• pp.1655-1666
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• 2003

It is experimentally well-known that high anisotropies of the turbulent flow field are dominant inside the tip leakage vortex, which is attributable to a substantial proportion of the total loss and constitutes one of the dominant mechanisms of the noise generation. This anisotropic nature of turbulence invalidates the use of the conventional isotropic eddy viscosity turbulence models based on the Boussinesq assumption. In this study, to check whether an anisotropic turbulence model is superior to the isotropic ones or not, the results obtained from the steady-state Reynolds averaged Navier-Stokes simulations based on the RNG k-$\varepsilon$ model and the Reynolds stress model (RSM) are compared with experimental data for two test cases: a linear compressor cascade and a forward-swept axial-flow fan. Through this comparative study of turbulence models, it is clearly shown that the RSM, which can express the production term and body-force term induced by system rotation without introducing any modeling, should be used to predict quantitatively the complex tip leakage flow, especially in the rotating environment.

• 대한기계학회논문집B
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• 제20권8호
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• pp.2681-2692
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• 1996

The finite-volume method for radiation in a three-dimensional non-orthogonal gas turbine combustion chamber with absorbing, emitting and anisotropically scattering medium is presented. The governing radiative transfer equation and its discretization equation using the step scheme are examined, while geometric relations which transform the Cartesian coordinate to a general body-fitted coordinate are provided to close the finite-volume formulation. The scattering phase function is modeled by a Legendre polynomial series. After a benchmark solution for three-dimensional rectangular combustor is obtained to validate the present formulation, a problem in three-dimensional non-orthogonal gas turbine combustor is investigated by changing such parameters as scattering albedo, scattering phase function and optical thickness. Heat flux in case of isotropic scattering is the same as that of non-scattering with specified heat generation in the medium. Forward scattering is found to produce higher radiative heat flux at hot and cold wall than backward scattering and optical thickness is also shown to play an important role in the problem. Results show that finite-volume method for radiation works well in orthogonal and non-orthogonal systems.

• 자원환경지질
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• 제37권1호
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• pp.35-48
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• 2004

본 논문에서는 폐광산지역의 오염특성 조사와 평가를 위한 지구화학적 접근방법에 대하여 정리ㆍ기술하였다. 폐광산지역의 주요 오염원은 갱내수, 광석, 광미 및 선광을 위해 사용한 화학약품 등이고 산성광산배수의 배출, 광산폐기물의 유실, 유해성 침출수의 배출, 광미와 분진의 분산 등에 의해 중금속이 이동/확산되어 주변토양, 퇴적물, 지표수, 지하수, 생태계에 광역적/지속적으로 심각한 영향을 미친다. 따라서 오염원, 주변 토양, 지표수, 지하수 등에 대한 화학분석, 광물학적분석, 광산산성배수 예측실험, 물리/지화학탐사와 같은 현장실험 등의 방법을 이용한 조사를 통해 폐광산이 주변 환경에 미치는 잠재적이고 실제적인 영향이 조사$.$평가 되어야한다.

• 한국해양공학회지
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• 제23권2호
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• pp.28-36
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• 2009

Many researches have been done to define the physical parameters for the wave generation and transformation over a coastal region. However, most of these have been limited to the application of particular conditions, as they are generally too empirical. To yield more reasonable wave estimation using a spectral wave model, it is important to understand how they work for the wave estimation. This study involved a comprehensive sensitivity test against the spectral resolution and the physical source/sink terms of the spectral wave model using SWAN and TOMAWAC, which have the same physical background with several different empirical/theoretical formulations. The tests were conducted for the East Anglian coast, UK, which is characterized by a complex bathymetry due to several shoals and offshore sandbanks. For the quantitative and qualitative evaluation of the models' performance with different input conditions, the wave elements and spectrums predicted at representative sites the East Anglia coast were compared/analyzed. The spectral resolution had no significant effect on the model results, but the lowest resolution on the frequency and direction induced underestimations of the wave height and period. The bottom friction and depth-induced breaking terms produced relatively high variations in the wave prediction, depending on which formulation was applied. The terms for the quadruplet and whitecapping had little effect on the wave estimation, whereas the triads tended to predict shorter and higher waves by energy transferring to higher frequencies.