Browsing by Author "Chiu, Yu-Chih"

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A Modified Lotka-Volterra Model for Diffusion and Substitution of Multigeneration DRAM Processing Technologies
(2017-01-01)
Hung, Hui-Chih
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Chiu, Yu-Chih
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Wu, Muh-Cherng
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工業工程與管理學系
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Department of Industrial Engineering and Management
We attempt to develop an effective forecasting model for the diffusion and substitution of multigeneration Dynamic Random Access Memory (DRAM) processing technologies. We consider market share data and propose a modified Lotka-Volterramodel, in which an additional constraint on the summation of market share is introduced. The mean absolute error is used to measure the accuracy of our market share predictions. Market share data in DRAM industries from quarter one (Q1) of 2005 to 2013 Q4 is collected to validate the prediction accuracy. Our model significantly outperforms other benchmark forecasting models of both revenue and market share data, including the Bass and Lotka-Volterra models. Compared to prior studies on forecasting the diffusion and substitution of multigeneration technologies, our model has two new perspectives: (1) allowing undetermined number of multigeneration technologies and inconsecutive adoption of new technologies and (2) requiring less data for forecasting newborn technologies.
An enhanced application of Lotka-Volterra model to forecast the sales of two competing retail formats
(2017-07-01)
Hung, Hui-Chih
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Chiu, Yu-Chih
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Huang, Huang-Chen
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Wu, Muh-Cherng
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工業工程與管理學系
This research develops a sales forecasting model that can analyze the interaction effects of two retail competing formats (convenience-oriented vs. budget-oriented formats). A traditional approach to making such a forecast is based on the Lotka-Volterra equations (also called the LV-model). The LV-model assumes that the population of each species is affected by its self-growth, internal interaction within the species, and external interaction with other species. Most prior studies in business applications directly use sales data as input to the LV-model. The prior approach may result in misleading conclusions when sales data are embedded with seasonal variation, because this variation is not addressed in the original development of the LV-model. Therefore, this study proposes a forecasting framework (an enhanced application of the LV-model). The sales data of each retail format is considered as a compound data, which is decomposed into three individual components: (1) aggregate, (2) competition, and (3) seasonal components. The LV-model is used to forecast the competition component; the other two components are forecasted by typical time series methods; and the data of three components are finally combined into one. Empirical study indicates that the proposed method substantially outperforms the prior approach in terms of forecasting errors (4.4% vs. 16.7% for convenience-oriented and 5.8% vs. 16.2% for budget oriented). In addition, the proposed method reveals a more convincing predator-prey relationship between the two retail formats, which concludes that the convenience-oriented is the predator. To the opposite, the prior approach, concluding that the budget-oriented is the predator, is quite doubtful because the convenience-oriented shall be preferred while the GDP grows over time. This research makes a contribution in how to appropriately apply the LV-model in forecasting revenue and analyzing the interaction effects of two competing business species. (C) 2017 Elsevier Ltd. All rights reserved.
Analysis of Competition Between IDM and Fabless-Foundry Business Models in the Semiconductor Industry
(2017-08-01)
Hung, Hui-Chih
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Chiu, Yu-Chih
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Wu, Muh-Cherng
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工業工程與管理學系
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Department of Industrial Engineering and Management
Three major business models are found in the semiconductor industry, namely, the integrated device manufacturer (IDM), fabless, and foundry models. IDMs design and manufacture integrated circuits (ICs), fabless companies focus only on IC design, and foundry companies are concerned only with IC manufacturing. The business model resulting when fabless and foundry companies form a strategic alliance is called the fabless-foundry model. Recently, the revenue growth rate of the fabless-foundry model has been considerably higher than that of IDM. This raises the question of whether the fabless- foundry model will ultimately dominate the semiconductor industry or grow only to a certain extent. To investigate this, we adopted the Hodrick-Prescott filter to remove the cyclic signal from original revenue data and then applied the Lotka-Volterra model to analyze the competition and cooperation relationships between pairs of these business models. The results reveal that the fabless and foundry models have a mutualistic relationship, whereas IDM competes with both the fabless and foundry models. IDM and the fabless- foundry model compete, but their revenues should ultimately arrive at an equilibrium point. In the long term, IDM and the fabless- foundry model should coexist; the ultimate market share of IDM is predicted to be approximately 55% and that of the fabless- foundry model approximately 45%.
Carboxylate-functionalized iron oxide nanoparticles in surface-assisted laser desorption/ionization mass spectrometry for the analysis of small biomolecules
(2008)
Chiu, Yu-Chih
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Chen, Yu-Chie
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應用化學系
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應用化學系分子科學碩博班
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Department of Applied Chemistry
Iron oxide particles have been demonstrated previously as an effective SALDI-assisted material in SALDI MS analysis. The addition of a proton source such as citrate salts is helpful for rendering ionization efficiency. To simplify the sample preparation steps, we immobilize polyacrylic acid (PAA) onto the surface of the iron oxide particles. The modified iron oxide particles can be used as the SALDI-assisted material without the addition of extra proton source. Small biomolecules including bradykinin, melittin, and insulin are used to examine the feasibility of this approach. The results show that the SALDI mass spectral results are improved by using polyacrylic acid (MWaverage= similar to 2 kDa) coated iron oxide nanoparticles.