• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.320-325
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• 2002

Today many companies offer millions of products to customers. They are faced with a problem to choose particular products . In response to this problem a new marking strategy, recommendation has emerged. Among recommendation technologies collaborative filtering is most preferred. But the performance degrades with the number of customers and products. Namely, collaborative filtering has two major limitations, sparsity and scalability. To overcome these problems we introduced a new recommendation methodology using adjusted product hierarchy, grain. This methodology focuses on dimensionality reduction to improve recommendation quality and uses a marketer's specific knowledge or experience. In addition, it uses a new measure in the neighborhood formation step which is the most important one in recommendation process.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.158-169
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• 2004

Recently companies are aggressively pushing ahead with integrating the systematical applications of internal and external information systems such as Data level, Application level, Process level in the company, Process level between companies. The EAI solution is generally considered as the necessary tool to integrate companies, but the appraisal standard for the EAI solution has not yet settled in Korea, so the companies have difficulty in deciding whether to adopt the EAI solution or not. Through this report, we first introduce the KRA Project as the best practice in making an application of the settled standard to evaluate and adopt the EAI solution, and then suggest that it can be adapted to companies considering applying to the EAI solution.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.99-115
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• 2004

From the growth of Internet technology, many e-commerce principles have been introduced in airline industry. The computer reservation systems(CRS) is the first real-time business application and considered as the earliest examples of e-commerce. In airlines, the early e-business activity was to build the web site for providing flight information to customers. Recently, many airlines are expanding the capability of the web site for selling tickets on the web to make use of the cheaper distribution channel. In this paper, we focus on the impacts of airline e-business being implemented in airline distribution channels. Using the conjoint analysis, we suggest a model for estimating the change of market sales for each distribution channel. With the empirical survey, we can find some implications on the e-business strategy and the effective internet marketing tools for airlines.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.10a
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• pp.644-647
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• 2004

Developing into information oriented society, dependency on network systems increases gradually in the area of economy, society and so on. Under that circumstance, temporary stop or damage of integrity of network system may have a strong impact on economic activities and overall society. Recently, threat of cyber terrorism, organized hostile action to government or industry through network, is increasing. Because of the features of network, it is not sufficient only a nation's countermeasure against Cyber terrorism, so international cooperation is needed. We review the status of countermeasure against cyber terrorism and examine several considerations for policy establishment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.1-9
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• 1999

The purpose of this study is to establish a basis for assessing construct validity of measures used in organizational research. The classic Campbell and Fiske's(1959) criteria are found to be lacking in their assumptions, diagnostic information, and power. The inherent confounding of measurement error with systematic trait and method effects is a severe limitation for a proper interpretation of convergent and discriminant validity. The confirmatory factor analysis(CFA) approach overcomes most of the limitations found in Campbell and Fiske's(1959) method. However, the CFA approach confounds random error with unique variance specific to a measure. The second-order confirmatory factor analysis(SOCFA) was shown to harbor rather restrictive assumptions and is unlikely to be met in practice. The first-order, multiple-informant, multiple-item(FOMIMI) model is a viable option, but it may also be of limited use because of the large number measures.

• ETRI Journal
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• v.39 no.6
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• pp.782-793
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• 2017

This paper considers the use of the Partial Transmit Sequence (PTS) technique to reduce the Peak-to-Average Power Ratio (PAPR) of an Orthogonal Frequency Division Multiplexing signal in wireless communication systems. Search complexity is very high in the traditional PTS scheme because it involves an extensive random search over all combinations of allowed phase vectors, and it increases exponentially with the number of phase vectors. In this paper, a suboptimal metaheuristic algorithm for phase optimization based on an improved harmony search (IHS) is applied to explore the optimal combination of phase vectors that provides improved performance compared with existing evolutionary algorithms such as the harmony search algorithm and firefly algorithm. IHS enhances the accuracy and convergence rate of the conventional algorithms with very few parameters to adjust. Simulation results show that an improved harmony search-based PTS algorithm can achieve a significant reduction in PAPR using a simple network structure compared with conventional algorithms.

• Korean Journal of Computational Design and Engineering
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• v.18 no.6
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• pp.407-416
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• 2013

Acting an important risk management tool for main contractors, pre-qualification has served a key marketing tool for subcontractors in various industries. Current industrial environment has required the time intensive pre-qualification ability to small and medium-size subcontractors as a matter of competitive business. In order to support the subcontractors, this paper proposes a database model for pre-qualification management system (PQMS) that automates the pre-qualification process by using information technologies. The modeling process consists of specifications for its requirements, functional modules, and a database model for the PQMS.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.124-131
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• 2008

Goal of "Single PPM Quality Innovation Movement" is to achieve perfect quality through participation of all members in the production line to achieve zero defects. Six Sigma has been used by many leading corporations as a tool for Management Innovation. Recently, the number of small and medium sized companies implementing Six Sigma has increased. Therefore, this research introduces the case of "S" company which utilized Six Sigma and Single PPM together to effectively implement Single PPM Quality Innovation Movement. This paper describes issues identified during the Single PPM Quality Innovation Movement implementation and also suggests improvement plans.

• Nuclear Engineering and Technology
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• v.37 no.2
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• pp.159-166
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• 2005

Human reliability assessment (HRA) is conducted on the unspoken premise that 'human error' is a meaningful concept and that it can be associated with individual actions. The basis for this assumption it found in the origin of HRA, as a necessary extension of PSA to account for the impact of failures emanating from human actions. Although it was natural to model HRA on PSA, a large number of studies have shown that the premises are wrong, specifically that human and technological functions cannot be decomposed in the same manner. The general experience from accident studies also indicates that action failures are a function of the context, and that it is the variability of the context rather than the 'human error probability' that is the much sought for signal. Accepting this will have significant consequences for the way in which HRA, and ultimately also PSA, should be pursued.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.786-796
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• 2014

This paper presents a new approach to design a robust tracking controller for linear time-invariant systems with uncertain time-delay. By introducing the model following control (MFC) structure which consists of two loops in nature, we show that the controller is capable of having a predictive control action and effectively tracking the reference output with a desired transient response as well. Three design techniques to achieve good tracking performance are suggested. It is also analytically shown that the tracking performance of the proposed scheme is more robust than that of typical single-loop feedback structure. An illustrative example is given to compare the tracking performances of the proposed methods with a single loop method.