• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.1001-1004
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• 2018

As the industry generates a lot of data, it is increasingly dependent on the IoT platform. For this reason, the performance and anomaly detection of IoT platform is becoming an important factor. In this paper, we propose a system model of IoT platform that detects device anomaly without performance issue. The proposed system uses Micro Batch which calculates the data transmission cycle to provide Soft Real-time service. In the industry, it was difficult to collect abnormal data, so the Hotelling's $T^2$ model was applied to the data analysis experiment. And the Hotelling's $T^2$ model successfully detected anomalies.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.313-323
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• 2003

For the growth curve model with arbitrary covariance structure, known as unstructured covariance matrix, the problems of detecting outliers are discussed in this paper. In order to detect outliers in the growth curve model, the test statistics using U-distribution is established. After detecting outliers in growth curve model, we test homo and/or hetero-geneous covariance matrices using PSR Quasi-Bayes Criterion. For illustration, one numerical example is discussed, which compares between before and after outlier deleting.

• Proceedings of the Technology Innovation Conference
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• 2006.02a
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• pp.78-102
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• 2006

Networks, services and industries have been converging with the advent of digital convergence by technology advancements of digitalization, broadband and interactivity in the areas of information-communication and broadcasting technologies. Especially, this convergence of technology and market has been blurring the boundary of telecommunication and broadcasting sectors, and the severe competition seems to be inevitable due to the lack of the differentiation in broadcasting media and contents. In this study, we regard the competition phenomenon in the digital convergence between telecommunication and broadcasting as the platform competition in two-sided markets which have been actively studied since 2000, and analyzed it using modified Hotelling's location model. According to the analysis of platform competition on the effects of the differentiation of platform (t) , killer component $(\mu)$ and component compatibility $(\theta)$ , it is shown that two differentiated platforms are simultaneously used in case of the decrease of substitution effects, and the profit of platform with killer contents is increased, but the profit of platforms with higher compatibility is decreased. The policy implication is that it is especially necessary to modify the policy and regulation on media contents considering the growing competition in media. On the other hand, differentiated and reasonable policy is required to make fair competition and active market environment.

• Korean Management Science Review
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• v.32 no.1
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• pp.83-100
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• 2015

We analyze a duopoly competition when two firms face input cost increases. The objective of this study is to determine the firms' optimal strategy between a price increase and downsizing under conditions of a spatially differentiated market and consumers' diminishing utility on the product size. We develop a theoretical model of two competing firms offering homogenous products using the standard Hotelling model to determine how firms' optimal strategies change when facing input cost increases. In this paper, there are two types of duopoly competitions: symmetric and asymmetric. In the symmetric case, the two firms have the same marginal cost and are producing and selling identical products. In the asymmetric case, the two firms have different marginal costs. The results show that the optimal strategy decision depends on the size of the input cost increase and the cost differences between the two firms. We find that when two firms are asymmetric (i.e., they have different marginal costs), the two firms might choose asymmetric pairs of strategies in equilibrium under certain conditions. When the cost differences between the two firms are sufficiently large and the cost increase is sufficiently small, the cost leader chooses price increase, and the cost-disadvantaged firm chooses downsizing in equilibrium. This asymmetric strategy reduces price competition between two firms, and consumers are better off. When the cost differences between the two firms are sufficiently large, downsizing is the dominant strategy for the cost-disadvantaged firm. The cost-disadvantaged firm finds it more profitable to reduce the product size than to increase its price to reduce price competition, because consumers prefer downsizing to price increases. This paper might be a good starting point for further analytical research in this area.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1282-1286
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• 2009

최근에 빈번하게 발생하는 집중호우로는 강우자료의 경향성에 영향을 주고 있다. 하지만, 우리나라의 강우관측기록이 충분하지 못하여 통계학적 경향성 분석은 유의한 결과를 보여주고 있지 않아, 확률강우량 산정시 강우자료가 정상성을 지니고 있다고 가정하여 빈도분석을 실시하고 있다. 본 연구에서는 경향성이 나타나지 않는 강우관측소 49개지점중 4개의 지점을 선정하여 향후 경향성 여부를 분석하였다. 이들 관측자료가 가지는 경향성을 유지하면서 추계학적 시계열 모의발생기법을 이용하여 강우자료를 발생시킨 후 경향성 검정을 실시하였다. 이를 위하여 Regression model, ARMA model을 이용하여 강우자료를 발생시켰으며, 발생된 강우자료는 Mann-Kendall test, Hotelling-Pabst test, Wald-Wolfowitz test를 사용하였다. 그 결과 거의 모든 지점에서 가까운 미래에 경향성을 갖게 될 것임을 알 수 있었다.

• The Korean Journal of Applied Statistics
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• v.22 no.6
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• pp.1355-1364
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• 2009

This work propose a robust test for location parameters in multivariate data based on MVE and MCD with the affine equivariance and the high-breakdown properties. We consider the hypothesis testing satisfying high efficiency and high test power simultaneously to bring in the one-step reweighting procedure upon high-breakdown estimators, which generally suffer from the low efficiency and, as a result, usually used only in the exploratory analysis. Monte Carlo study shows that the suggested method retains nominal significance levels and higher testing power without regard to various population distributions than a Hotelling's $T^2$ test. In an example, a data set containing known outliers does not make an influence toward our proposal, while it renders a Hotelling's $T^2$ useless.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.338-346
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• 2006

In semiconductor process, it is so hard to predict an exact failure point of the vacuum pump due to its harsh operation conditions and nonlinear properties, which may causes many problems, such as production of inferior goods or waste of unnecessary materials. Therefore it is very urgent and serious problem to develop diagnostic models which can monitor the operation conditions appropriately and recognize the failure point exactly, indicating when to replace the vacuum pump. In this study, many influencing factors are totally considered and eventually the monitoring model using multivariate statistical methods is suggested. The pivotal algorithms are Multiway Principal Component Analysis(MPCA), Dynamic Time Warping Algorithm(DTW Algorithm), etc.

• The Journal of the Convergence on Culture Technology
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• v.8 no.3
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• pp.405-413
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• 2022

Since the COVID-19 outbreak, the active utilization of new health care service utilizing the ICT technology and data science such as telemedicine, smart hospital, AI dignosis has been increasingly found. In this study we examined the business model of Amazon healthcare which leads disruptive innovation in U.S. health care industry with the introduction of hybrid model of telemedicin, in-person care and customer-centric online drug delivery, home-use diagnostic kit, characterized by the integrated model combining medical care, drug delivery and the use of diagnostic kit. We showed using the multiproduct competition model that the synergy effect between the Amazon's original business areas and the healthcare business area causes the active market penetration and the increase in the customer value from utilization of the Amazon care. Using Hotelling's spatial competition model, we also showed that the competition in the health care market can be greater when consumer's choice of health care providers are available in telemedicine platform. In the long, run the issue of competition being weakened due to the exit of less competent healthcare providers may arise, to which the policymakers in the charge of fair competition in health care industry should pay attention.

• The Korean Journal of Applied Statistics
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• v.5 no.2
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• pp.283-292
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• 1992

Updating algorithms are studied for the basic statistics (mean, variance). For a linear model, a recursive formulae for least squares estimators of regression coefficients, residual sum of squares and variance-covariance matrix are also studied. Hotelling's $T^2$ statistics can be calculated recursively using the recursive formulae of mean vector and variance-covariance matrix without computing the sample variance-covariance matrix at each stage.

• Journal of Korean Institute of Industrial Engineers
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• v.31 no.4
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• pp.277-288
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• 2005

The proliferation of the internet technologies and applications has intensified business activities on the Internet. This study considered the price competition between two shopping channels, one on-line seller and the other traditional off-line retailer. Based on the Hotelling's linear market model, we derive the Nash and Stackelberg equilibria as a function of the cost parameters which represent the characteristics of the online and off-line channels. By analyzing the equilibrium solutions, the following significant findings were obtained. First, pricing by Stackelberg equilibrium always outperformed that of Nash equilibrium. However the value of the cost parameters played a crucial role in determining both channels' preferred position (price leader or follower). Second, the online seller could benefit more in terms of profit by lowering its efficiency when its efficiency belongs to a certain interval. Third, when the online seller's efficiency is low, lowering its delivery cost has no contribution to its profit. To benefit more from lowering its delivery cost, increasing its channel efficiency to a certain level should be preceded.