• 대한조선학회논문집
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• 제41권1호
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• pp.1-7
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• 2004

GUI program for analyzing directional spectrum waves is introduced in this paper Basically, MLM (Maximum Likelihood Method) was used for this program which was additionally consisted of performing spectral and time domain analysis for two dimensional irregular waves. Moreover, the directionality of directional spectrum waves generated by single summation and double summation method was investigated based on MLM. The directionality from each summation method has good agreement compared with that of target wave spreading function in the case of single wide directional spectrum waves. In addition to this, the resolution of directionality in double summation method was investigated as introducing coherence function between each wave component

• 대한조선학회논문집
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• 제42권3호
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• pp.212-219
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• 2005

Real sea waves in a towing wave basin have been generated using random periodic motion of the segmented wave makers and the wave reflections of sidewalls. Theoretically, the real sea waves can be described by the superposition of many random oblique waves. This paper introduces numerical real sea wave generation in a rectangular wave basin using spectral method that uses a superposition of orthogonal functions which have to satisfy the Laplace equation. Oblique regular waves, long crested irregular waves and real sea waves were simulated and met the requirement of sidewall wave reflection and wave absorption. MLM (Maximum Likelihood Method) and Spatial Fourier Transform were used in order to obtain propagated wave direction characteristics. The estimated results proved the usefulness of the method and the performances showed reasonable directional patterns comparing with generating patterns.

• 유통과학연구
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• 제17권3호
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• pp.5-19
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• 2019

Purpose - The purpose of this research is to investigate the factors contributing to sustainable competitive advantage for multi-level marketing (MLM) firms in Malaysia. The selected variables in this study are company image, product innovation, leadership, distributor rewards system and distributor training system. Research design, data, and methodology - Quantitative research method is employed with collected sample size of 398 respondents using judgmental sampling technique. Normality and reliability test were performed in the first stage utilizing SPSS 22 and Confirmatory Factory Analysis (CFA) and variance analysis were obtained in the subsequent stage, following up with the overall fit of the measurement model, Structural Equation Model (SEM) using AMOS 22 with maximum likelihood estimation to assess the internal consistency, convergent validity and discriminant validity. Results - The research findings show that company image, leadership, distributor rewards system and distributor training system were supported and are factors affecting the sustainable competitive advantage of MLM companies in Malaysia. However, in this study, product innovation was not supported but this result does not depict that it is trivial and inconsequential in maintain sustainable advantage. Conclusion - Companies can build sustainable competitive advantage by focusing on these contributing factors. Several other comments and implications were brought to light and discussed in the paper.

• 대한조선학회논문집
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• 제60권4호
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• pp.266-277
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• 2023

In this study, fundamental research is conducted for the generation technique and analysis of multi-directional irregular waves in the Deep Ocean Engineering Basin (DOEB). A three-dimensional boundary element method-based numerical tank is implemented to perform wave generation simulations, and directional spectrum estimation is carried out using the results of simulations. The wave generation technique of the Snake type wave maker, generating multi-directional irregular waves, is implemented using the Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) algorithms. The wave generation technique is validated by comparing the wave spectrum from simulations and experiments. A Maximum Likelihood Method (MLM) based estimation code is developed for estimating the directional wave spectra. The multi-directional irregular waves are tested in the DOEB and the numerical tank, and directional wave spectra obtained from two methodologies are estimated and compared. A correction procedure for the directional distribution of multi-directional waves is established, and the possibility of correcting the directional spreading function using the numerical tank is validated.

• 한국환경과학회지
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• 제28권1호
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• pp.19-35
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• 2019

This study investigates the performance of four Bayesian methods, Random Walk Metropolis (RWM), Hit-And-Run Metropolis (HARM), Adaptive Mixture Metropolis (AMM), and Population Monte Carlo (PMC), for estimating the parameters and uncertainties of probability rainfall distribution, and the results are compared with those of conventional parameter estimation methods; namely, the Method Of Moment (MOM), Maximum Likelihood Method (MLM), and Probability Weighted Method (PWM). As a result, Bayesian methods yield similar or slightly better results in parameter estimations compared with conventional methods. In particular, PMC can reduce parameter uncertainty greatly compared with RWM, HARM, and AMM methods although the Bayesian methods produce similar results in parameter estimations. Overall, the Bayesian methods produce better accuracy for scale parameters compared with the conventional methods and this characteristic improves the accuracy of probability rainfall. Therefore, Bayesian methods can be effective tools for estimating the parameters and uncertainties of probability rainfall distribution in hydrological practices, flood risk assessment, and decision-making support.