• 한국음향학회지
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• 제13권2호
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• pp.30-37
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• 1994

최근 표적의 고속화와 저표적강도화 추세에 따라 표적 탐지의 정확성이 요구되고 있다. 본 연구는 이에 부합하여 표적 운동 해석, 표적 분류, 소나 성능 예측 모델의 개발에 필수적인 표적 산란 잔향 신호의 주파수 및 시간별 특성의 파악과 그러한 특성을 포함한 표적 신호 시뮬레이션에 목적을 두고 있다. 표적 신호 시뮬레이션에는 음향 변환자 배열의 음원 준위와 빔패턴으로 구성되는 음원모델, 전달 손실 예측부인 환경모델, 복합 표적에 의한 신호의 신장 및 표적 강도와 음원과 표적의 상대운동을 표현하는 도플러 현상이 고려된 표적모델, 수신기의 감도 및 빔패턴과 각 채널의 시간이 고려된 수신 모델 등 주요한 4부분의 모델이 필요하다. 개발된 MOST(MOving Spread Target) 신호합성기는 환경모델을 제외한 3가지 모델로 구성 되어 있으며, 음원과 표적의 운동에 의한 신호 특성 시뮬레이션 등의 기능을 갖추고 있어, 소나 운용 체계 개발의 한 단계인 HILS(Hardware In the Loop Simulation)와 표적 상태 추정을 위한 신호 특성 분석 및 앞에서 언급한 각종 모델에서 신호 발생 장치로 이용될 수 있다.

• 디지털산업정보학회논문지
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• 제13권1호
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• pp.125-133
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• 2017

Color in an image is determined by illuminant and surface reflectance. So, to recover unique color of object, estimation of exact illuminant is needed. In this study, the illumination models suggested to get the object color constancy with the physical illumination model based on physical phenomena. Their characteristics and application limits are presented and the necessity of an extended illumination model is suggested to get more appropriate object colors recovered. The extended illumination model should contain an additional term for the ambient light in order to account for spatial variance of illumination in object images. Its necessity is verified through an experiment under simple lighting environment in this study. Finally, a reconstruction method for recovering input images under standard white light illumination is experimented and an useful method for computing object color reflectivity is suggested and experimented which can be induced from combination of the existing illumination models.

• Journal of the Korean Statistical Society
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• 제28권2호
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• pp.167-182
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• 1999

This article is concerned with the selection of subsets of predictor variables to be included in building the binary response probit regression model. It is based on a Bayesian approach, intended to propose and develop a procedure that uses probabilistic considerations for selecting promising subsets. This procedure reformulates the probit regression setup in a hierarchical normal mixture model by introducing a set of hyperparameters that will be used to identify subset choices. The appropriate posterior probability of each subset of predictor variables is obtained through the Gibbs sampler, which samples indirectly from the multinomial posterior distribution on the set of possible subset choices. Thus, in this procedure, the most promising subset of predictors can be identified as the one with highest posterior probability. To highlight the merit of this procedure a couple of illustrative numerical examples are given.

• 한국지구과학회지
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• 제40권4호
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• pp.392-405
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• 2019

Biogeochemical processes play an important role in ocean environments and can affect the entire Earth's climate system. Using an ocean-biogeochemistry model (NEMO-TOPAZ), we investigated the effects of changes in albedo and wind stress caused by phytoplankton in the equatorial Pacific. The simulated ocean temperature showed a slight decrease when the solar reflectance of the regions where phytoplankton were present increased. Phytoplankton also decreased the El $Ni{\tilde{n}}o$-Southern Oscillation (ENSO) amplitude by decreasing the influence of trade winds due to their biological enhancement of upper-ocean turbulent viscosity. Consequently, the cold sea surface temperature bias in the equatorial Pacific and overestimation of the ENSO amplitude were slightly reduced in our model simulations. Further sensitivity tests suggested the necessity of improving the phytoplankton-related equation and optimal coefficients. Our results highlight the effects of altered albedo and wind stress due to phytoplankton on the climate system.

• Advances in nano research
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• 제7권3호
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• pp.181-190
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• 2019

The thermal buckling temperature values of the graded carbon nanotube reinforced composite shell structure is explored using higher-order mid-plane kinematics and multiscale constituent modeling under two different thermal fields. The critical values of buckling temperature including the effect of in-plane thermal loading are computed numerically by minimizing the final energy expression through a linear isoparametric finite element technique. The governing equation of the multiscale nanocomposite is derived via the variational principle including the geometrical distortion through Green-Lagrange strain. Additionally, the model includes different grading patterns of nanotube through the panel thickness to improve the structural strength. The reliability and accuracy of the developed finite element model are varified by comparison and convergence studies. Finally, the applicability of present developed model was highlight by enlighten several numerical examples for various type shell geometries and design parameters.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1382-1393
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• 2022

This paper investigates the seismic behavior of an electrical cabinet considering the influence of equipment-anchor-interaction (EAI) that is generally not taken into consideration in a decoupled analysis. The hysteresis behavior of an anchor bolt in concrete was thereby considered to highlight this interaction effect. To this end, the experimental behavior of an anchor bolt under reversed cyclic loading was taken from the recently developed literature, and a numerical model for the anchor hysteresis was developed using the component approach. The hysteresis properties were then used to calibrate the multi-linear link element that is implemented as a boundary condition for the cabinet incorporating the EAI. To highlight this EAI further, the nonlinear time history analysis was performed for a cabinet considering the hysteresis behavior comparative to a fixed boundary condition. Additionally, the influence on the seismic fragility was evaluated for the operational and structural condition of the cabinet. The numerical analysis considering the anchor hysteresis manifests that the in-cabinet response spectra (ICRS) are significantly amplified with the corresponding reduction in the seismic capacity of 25% and 15% for an operational and structural safety condition under the selected protocols. Considering the fixed boundary condition over a realistic hysteresis behavior of the anchor bolt is more likely to overestimate the seismic capacity of the cabinet in a seismic qualification procedure.

• 한국가정과교육학회지
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• 제13권1호
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• pp.1-11
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• 2001

Home economics education professional knowledge consists of empirical interpretive critical science component. Thus it is imperative that the alternative research perspectives be used to gain certain knowledge for the profession of home economics education. In human inquiry and education there is a growing concern that the dominant research paradigm positivist natural science model is inadequate to address the phenomena constructed by persons. However, Home economics education has not examined and almost utilized alternative research perspectives. This review will probe research logic and resecrach methodology of qualitative inquiry within home economics education and highlight the shift from positivism to post-positivism.

• 대한수학회보
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• 제47권5호
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• pp.889-905
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• 2010

In this paper, a distribution free approach to the parameter estimation of a simple bilinear model with periodic coefficients is presented. The proposed method relies on minimum distance estimator based on the autocovariances of the squared process. Consistency and asymptotic normality of the estimator, as well as hypotheses testing, are derived. Numerical experiments on simulated data sets are presented to highlight the theoretical results.

• 한국기계연구소 소보
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• 통권19호
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• pp.163-169
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• 1989

Many computer programs are being developed to aid the design of physical models. These efforts highlight the importance of computer model of three dimensional object. In this paper a CAD application program is introduced which can be implemented to modeling some part that composed with 3 types of surface form ; free form surface, fillt surface, surface of revolution, and a geometry description language which can represent a shape efficiently is preseneted.

• Journal of the Korean Statistical Society
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• 제29권4호
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• pp.407-422
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• 2000

This article is concerned with the selecting predictor variables to be included in building a class of binary response t-link regression models where both probit and logistic regression models can e approximately taken as members of the class. It is based on a modification of the stochastic search variable selection method(SSVS), intended to propose and develop a Bayesian procedure that used probabilistic considerations for selecting promising subsets of predictor variables. The procedure reformulates the binary response t-link regression setup in a hierarchical truncated normal mixture model by introducing a set of hyperparameters that will be used to identify subset choices. In this setup, the most promising subset of predictors can be identified as that with highest posterior probability in the marginal posterior distribution of the hyperparameters. To highlight the merit of the procedure, an illustrative numerical example is given.