• International Journal of Ocean System Engineering
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• 제3권4호
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• pp.225-230
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• 2013

This paper introduces the experimental results of sloshing model tests carried out at Seoul National University. Two 1/50-scale tanks, i.e., 2D and 3D models with the same shape, were manufactured for the comparative study. Particular interest was taken in the differences in impact pressures between the 2D and 3D models. Regular motion tests were conducted for different filling depths. For each filling depth, 500 cycles of regular excitation were imposed at each frequency. To observe the characteristics and severity of sloshing from the acquired pressure data, statistical analyses were performed, not only for the peak pressure, but also for the area-concept indices, which represented the amount of impulse.

• 제어로봇시스템학회논문지
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• 제16권4호
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• pp.335-338
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• 2010

A new method that improves the performance of large scale voice dialling system is presented using speaker adaptation. Since SI (Speaker Independent) based speech recognition system with phoneme HMM uses only the phoneme string of the input sentence, the storage space could be reduced greatly. However, the performance of the system is worse than that of the speaker dependent system due to the mismatch between the input utterance and the SI models. A new method that estimates the phonetic string and adaptation vectors iteratively is presented to reduce the mismatch between the training utterances and a set of SI models using speaker adaptation techniques. For speaker adaptation the stochastic matching methods are used to estimate the adaptation vectors. The experiments performed over actual telephone line shows that proposed method shows better performance as compared to the conventional method. with the SI phonetic recognizer.

• 천문학회보
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• 제42권1호
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• pp.41.2-42
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• 2017

We are planning to conduct Monte Carlo simulations for the Na exospheres of the Moon including localized sources on the surface in addition to the global isotropic and anisotropic sources, which were previously studied. The simulation models are based on Lee et al. (2011), who presented a satisfactory interpretation for the isotropic and anisotropic sources of the Lunar Na exosphere. We will compare our preliminary models with existing and the future lunar tail/exospheric observations by the LADEE and NASA's coronagraph-monitoring programs. Ground-based data show global-scale outflows of Na in contrast to small-scale data usually obtained near the orbits of spacecraft.

• 천문학회보
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• 제43권1호
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• pp.62.2-62.2
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• 2018

From the gaussian, near scale-invariant density perturbations observed in the CMB to the late time clustering of galaxies, CDM provides a minimal theoretical explanation for a variety of cosmological data. However accepting this explanation, requires that we include within our cosmic ontology a vacuum energy that is ~122 orders of magnitude lower than QM predictions, or alternatively a new scalar field (dark energy) that has negative pressure. Alternatively, modifications to Einstein's General Relativity have been proposed as a model for cosmic acceleration. Recently there have been many works attempting to test for modified gravity using the large scale clustering of galaxies, ISW, cluster abundance, RSD, 21cm observations, and weak lensing. In this work, we compare various modified gravity models using cosmic shear data from the Deep Lens Survey as well as data from CMB, SNe Ia, and BAO. We use the Bayesian Evidence to quantify the comparison robustly, which naturally penalizes complex models with weak data support. In this poster we present our methodology and preliminary constraints on f(R) gravity.

• Computers and Concrete
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• 제12권4호
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• pp.565-583
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• 2013

Existing numerical models for strain-hardening cement-based composites (SHCC) are short of providing sufficiently accurate solutions to the failure patterns of coupling beams of different designs. The objective of this study is to develop an effective model that is capable of simulating the nonlinear behavior of SHCC coupling beams subjected to cyclic loading. The beam model proposed in this study is a macro-scale plane stress model. The effects of cracks on the macro-scale behavior of SHCC coupling beams are smeared in an anisotropic model. In particular, the influence of the defined crack orientations on the simulation accuracy is explored. Extensive experimental data from coupling beams with different failure patterns are employed to evaluate the validity of the proposed SHCC coupling beam models. The results show that the use of the suggested shear stiffness retention factor for damaged SHCC coupling beams is able to effectively enhance the simulation accuracy, especially for shear-critical SHCC coupling beams. In addition, the definition of crack orientation for damaged coupling beams is found to be a critical factor influencing the simulation accuracy.

• Journal of the Korean Statistical Society
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• 제25권3호
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• pp.347-358
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• 1996

A new test for goodness-of-fit is presented. It is a modification of a test of LaRiccia (1991). These tests are applicable to continuous lo-cation/scale models. The new test statistic is based on a few selected order statistics taken from the sample, while the LaRiccia test is based directly on the full sample. Each test embeds the hypothesized model in a larger linear model and proceeds to test the goodness-of-fit hy-pothesis by testing the coefficients of this linear model appropriately. The general theory is presented. The tests are compared via computer simulation to a related test of Ali and Umbach (1989) for distributions that could be used as lifetime models. An important aspect of all these tests is that only standard $X_2$ tables are used. Selection of the spacings of the order statistics is discussed.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.183-195
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• 2014

Kinetically constrained models (KCM) have attracted interest as models that assign dynamic origins to the interesting dynamic properties of supercooled liquid. Signs of dynamic heterogeneity in the crossover model that linearly interpolates between the FA-like symmetric constraint and the East model constraint by asymmetric parameter b were investigated using Monte Carlo technique. When the asymmetry parameter was decreased sufficiently, smooth fragile-to-strong dynamic transition was observed in terms of the relaxation time, diffusion constant, Stokes-Einstein violation, and dynamic length scale. Competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism is behind such transition.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권2호
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• pp.199-209
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• 2013

This paper presents the model test results of 3 new spar platforms which were developed based on the OC3-Hywind spar to support a 5-MW wind turbine. By changing the shape but keeping both volume and mass of OC3-Hywind spar platform, those platforms were expected to experience different hydrodynamic and hydrostatic loads. The scale models were built with a 1/128 scale ratio. The model tests were carried out in waves, including both rotating rotor effect and mean wind speed. The characteristic motions of the 3 new models were measured; Response Amplitude Operators (RAO) and significant motions were calculated and compared with those of OC3-Hywind.

• 천문학회지
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• 제28권2호
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• pp.109-117
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• 1995

The morphology and strength of the primordial magnetic field which is generated spontaneously in the early universe are studied for three models: (1) inflation (2) primordial magnetized bubble and (3) primordial turbulence models, We calculate the power spectra of magnetic field that are scale-free and proportional to $k^{1.5},k^{3{\sim}4}$ and $k^{2/3}$, respectively. The configurations of magnetic field having these power spectra are visualized. To constrain the present strength of the primordial magnetic field we calculate the anisotropy of the microwave background radiation in Bianchi type I universe with globally homogeneous magnetic field. From the COBE limit of the quadrupole moment of $({\delta}T/T)_{l=2}$ the present strength of horizen-scale magnetic fields $B_p$ is constrained to be less than $9{\times}10^{-8}G$.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1339-1345
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• 2017

In the framework of the EU funded project NURESAFE, the subchannel code CTF and the neutronics code DYN3D were integrated and coupled on the NURESIM platform. The developments achieved during this 3-year project include assembly-level and pin-by-pin multiphysics thermal hydraulics/neutron kinetics coupling. In order to test this coupling, a PWR rod ejection transient was simulated on a MOX/UOX minicore. The transient is simulated using two different models of the minicore. In the first simulation, both codes model the core with an assembly-wise resolution. In the second simulation, a pin-by-pin fuel-centered model is used in CTF for the central assembly, and a pin power reconstruction method is applied in DYN3D. The analysis shows the influence of the different models on global parameters, such as the power and the average fuel temperature, but also on local parameters such as the maximum fuel temperature.