Oh J.,Hansung University |
Haas Z.J.,Cornell University
IEEE Communications Magazine | Year: 2010
The vision behind the personal environment service is that of recreating a user's customized living or working surroundings in accordance with user-defined settings and in response to the user's mobility. Concepts such as ambient intelligence and home networks could be instrumental in realization of PES. Indeed, integration of elements of these technologies may attract industrial attention and support, which in turn may speed up the implementation and deployment of PES. Moreover, underlying technologies related to the above concepts are envisioned to play a key role in the realization of PES, including mobile communications supported by ubiquitous infrastructure and wireless personal area networks. In this article we present a simple PES network architecture and its underlying network technologies, and we discuss a set of potential services of PES. We also compare PES with other related concepts capable of supporting the PES vision. © 2010 IEEE.
Choi K.,Hansung University |
Narasimhan R.,Michigan State University |
Kim S.W.,Seoul National University
Journal of Operations Management | Year: 2012
This paper contributes to research on "postponement" strategy in the context of a global production-distribution system of an automobile manufacturer. It proposes a model that integrates multiple considerations germane to global SUPPL.y chains. Postponement is important in this context because it is necessary to consider international transfers and tariffs, and it is important to appropriately account for the impact of postponement on total costs. Consideration of several key variables such as shipping point, customs tariff, and cost differences between countries is essential to derive full benefits from postponement strategy in global SUPPL.y chains. International transfer of goods among countries in global automobile industry is complex and dynamic because of the multitude of factors that must be considered. The paper develops insights regarding postponement strategy in global SUPPL.y chains via a system dynamics simulation model. The model draws on the experiences of a Korean automobile manufacturer with operations in developing and developed countries. The results of the system dynamics simulations show that the choice of optimal shipping point and the right level of postponement under the "decoupling points" strategy in global operations has a significant effect on overall cost efficiency, when decoupling point and postponement timing are considered simultaneously. The results also show that there are key differences in executing the postponement strategy when shipping to a developing country as opposed to a developed country. This insight has practical implications for global operations and is helpful in developing a sophisticated framework for executing the postponement strategy as manufacturing firms expand their operations globally. © 2011 Elsevier B.V. All rights reserved.
Woo Y.,Hansung University
CAD Computer Aided Design | Year: 2014
Abstraction of mid-surfaces from solid models of thin-walled parts is becoming a useful function for idealizing the solid models for engineering analysis. Various abstraction techniques have been developed and adapted to commercial CAD systems. However, they are generally lacking in completeness and robustness. That is, for some complex solid models, valid mid-surfaces are not created and mid-surfaces which are created may not be valid or of little use in practice. Existing techniques utilize rules and heuristics in detecting appropriate face-pairs and generating mid-surface patches, but these rules and heuristics often do not apply to complex solid models. To address this problem, a divide-and-conquer approach to mid-surface abstraction is proposed in this paper. A solid model is decomposed into simple volumes, and mid-surfaces of the simple volumes are abstracted. The mid-surfaces of the simple volumes are then composed into the mid-surfaces of the original solid model. The proposed method has been implemented and tested with practical examples. The results of case studies have been presented to attest to the usefulness of the proposed method. Some general issues on mid-surface abstraction are also discussed. © 2013 Elsevier Ltd. All rights reserved.
Lee H.,Hansung University
IEEE Transactions on Wireless Communications | Year: 2015
In the paper 'Error Performance of Transmit Beamforming With Delayed and Limited Feedback' of Ma et al., they provided the analytical derivation of an accurate approximation for the symbol error rate (SER) of transmit beamforming (TB) systems employing $M$-ary phase-shift keying ( $M$-PSK) in Rayleigh fading channels, considering the effect of delayed and limited-rate codebook index feedback. However, the derived formula is valid only for the binary phase-shift-keying (i.e., $M=2$) modulation, which means that the formula is not general for the $M$-PSK modulations with $M\geq 2$. Therefore, we aim at deriving the correct closed-form formula for the accurate approximation for the SER, which is validated through the numerical results. Furthermore, we also present the corresponding correct coding gain achieved by the TB system. © 2014 IEEE.
Animesh A.,McGill University |
Pinsonneault A.,McGill University |
Yang S.-B.,Hansung University |
Oh W.,Yonsei University
MIS Quarterly: Management Information Systems | Year: 2011
Although research on three-dimensional virtual environments abounds, little is known about the social and business aspects of virtual worlds. Given the emergence of large-scale social virtual worlds, such as Second Life, and the dramatic growth in sales of virtual goods, it is important to understand the dynamics that govern the purchase of virtual goods in virtual worlds. Employing the stimulus-organism-response (S-O-R) framework, we investigate how technological (interactivity and sociability) and spatial (density and stability) environments in virtual worlds influence the participants' virtual experiences (telepresence, social presence, and flow), and how experiences subsequently affect their response (intention to purchase virtual goods). The results of our survey of 354 Second Life residents indicate that interactivity, which enhances the interaction with objects, has a significant positive impact on telepresence and flow. Also, sociability, which fosters interactions with participants, is significantly associated with social presence, although no such significant impact was observed on flow. Furthermore, both density and stability are found to significantly influence participants' virtual experiences; stability helps users to develop strong social bonds, thereby increasing both social presence and flow. However, contrary to our prediction of curvilinear patterns, density is linearly associated with flow and social presence. Interestingly, the results exhibit two opposing effects of density: while it reduces the extent of flow, density increases the amount of social presence. Since social presence is found to increase flow, the net impact of density on flow depends heavily on the relative strength of the associations involving these three constructs. Finally, we find that flow mediates the impacts of technological and spatial environments on intention to purchase virtual products. We conclude the paper with a discussion of the theoretical and practical contributions of our findings.
Lee D.-J.,Hansung University |
Ahn J.-H.,Korea Advanced Institute of Science and Technology |
Bang Y.,Korea Advanced Institute of Science and Technology
MIS Quarterly: Management Information Systems | Year: 2011
Advances in information technology and e-commerce enable firms to make personalized offers to individual consumers based on information about the consumers. However, the collection and use of private information have caused serious concerns about privacy invasion by consumers, creating a personalization-privacy tradeoff. The key approach to address privacy concerns is via the protection of privacy through the implementation of fair information practices, a set of standards governing the collection and use of personal information. In this paper, we take a game-theoretic approach to explore the motivation of firms for privacy protection and its impact on competition and social welfare in the context of product and price personalization. We find that privacy protection can work as a competition-mitigating mechanism by generating asymmetry in the consumer segments to which firms offer personalization, enhancing the profit extraction abilities of the firms. In equilibrium, both symmetric and asymmetric choices of privacy protection by the firms can result, depending on the size of the personalization scope and the investment cost of protection. Further, as consumers become more concerned about their privacy, it is more likely that all firms adopt privacy protection. In the perspective of welfare, we show that autonomous choices of privacy protection by personalizing firms can improve social welfare at the expense of consumer welfare. We further find that regulation enforcing the implementation of fair information practices can be efficient from the social welfare perspective mainly by limiting the incentives of the firms to exploit the competition-mitigation effect.
Im I.,Yonsei University |
Hong S.,Sangmyung University |
Kang M.S.,Hansung University
Information and Management | Year: 2011
We examined the relationships of the constructs in the UTAUT model to determine how they are affected by culture. In our study, we used data from Korea and the U.S. to examine two technologies: the MP3 player and Internet banking. Results showed that the UTAUT model fits our data well. The comparison of Korea and the U.S. revealed that the effects of effort expectancy on behavioral intention and the effects of behavioral intention on use behavior were greater in the U.S. sample. The implications of this are discussed. © 2010 Elsevier B.V.
Lee J.M.,Hansung University
Information Processing Letters | Year: 2010
A new flocking algorithm that yields an improvement in the execution time over the existing method known as the spatial subdivision method is discussed. In order to achieve this, the characteristic of flocking behavior is analyzed experimentally, in which two agents may share many common neighbors if they are spatially close to each other. It is also shown that it can be applied to the spatial subdivision method by introducing the Theorem and Corollary. A number of experiments were conducted to evaluate the performance of the proposed algorithm. Results of experiments demonstrated improvement of 43% in the execution time when compared with the conventional spatial subdivision algorithm.
Heo J.,Hansung University |
Yang J.Y.,Hansung University
Applied Soft Computing Journal | Year: 2014
A lot of bankruptcy forecasting model has been studied. Most of them uses corporate finance data and is intended for general companies. It may not appropriate for forecasting bankruptcy of construction companies which has big liquidity. It has a different capital structure, and the model to judge the financial risk of general companies can be difficult to apply the construction companies. The existing studies such as traditional Z-score and bankruptcy prediction using machine learning focus on the companies of non-specific industries. The characteristics of companies are not considered at all. In this paper, we showed that AdaBoost (adaptive boosting) is an appropriate model to judge the financial risk of Korean construction companies. We classified construction companies into three groups - large, middle, and small based on the capital of a company. We analyzed the predictive ability of the AdaBoost and other algorithms for each group of companies. The experimental results showed that the AdaBoost has more predictive power than others, especially for the large group of companies that has the capital more than 50 billion won. © 2014 Elsevier B.V.
Ji J.,Hansung University
Exploration Geophysics | Year: 2012
In spite of some minor drawbacks such as nonuniqueness and higher computational cost, finding the least-absolute (l 1 norm) error solution to solve an optimisation problem is mostly known to give a better answer than the classical least-squares (l 2 norm) method. This is because the robust property of the median value is affected little by outlier values and the solution of the least l 1 norm error corresponds to the solution of minimum median error. Several variants of the l1 norm such as the Huber norm and the Hybrid norm have the same robust properties as the l 1 norm. The optimisation methods based on l 1 norm obtain their robustness by reducing the influence of outliers significantly, although never ignoring it. Therefore, if the proportion of outliers increases, most of the methods based on l 1 norm may begin to be affected by the outliers. In such a case, other types of robust measures such as Tukey's Biweight (Bisquare weight) norm, which excludes outliers in computing the misfit measure, could perform better. This paper describes the application of the Biweight norm using the IRLS (iteratively reweighted least-squares) method as a robust inversion and shows its possible improvement in robustness when dealing with data having many outliers. © 2012 ASEG.