• Journal of Korean Society for Quality Management
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• v.27 no.4
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• pp.229-240
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• 1999

Drawbacks of using sigma level as a performance metric is reviewed. The concept of sigma level is introduced and methods of calculating sigma levels for various cases are illustrated with examples. Drawbacks of using sigma level as performance metric are also discussed with some suggestions for overcoming them.

• Proceedings of the CALSEC Conference
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• 1998.10b
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• pp.457-466
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• 1998

Internet-based EDI is emerging as a prominent substitute technology for traditional VAN-based EDI technology. The strength of this new technology is based on the explosive growth of Internet community, low "fixed-rate" Internet expense and "globally" open base of its participants. These strengths of Internet-baed EDI bring vast new opportunities for enterprises and thus. have as much implications for IT managers. However, Internet-based EDI technology has, at least by now, several drawbacks too. Most of these drawbacks also comes from the fact that it has its structural base on the Internet. Managers should carefully consider these drawbacks and hidden costs before adopting or switching to this attractive new technology. This presentation attempts to address major trends of Internet-based EDI and its implementation, opportunities and threats of the changes in technology, factors to consider in adopting this technology, and several managerial and strategic tradeoffs and implications of Internet-based EDI for IT managers.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.102-107
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• 2009

The Possibilistic C-means(PCM) was proposed to overcome some of the drawbacks associated with the Fuzzy C-means(FCM) such as improved performance for noise data. However, PCM possesses some drawbacks such as sensitivity in initial parameter values and to patterns that have relatively short distances between the prototypes. To overcome these drawbacks, we propose an interval type 2 fuzzy approach to PCM by considering uncertainty in the fuzzy parameter m in the PCM algorithm.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.935-936
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• 2007

Industry of street lighting systems are growing rapidly and going to complexwith rapid growth of industry and cities. To control and maintain complex street lighting system more economically, various street light control systems are developed. Nevertheless most of developed systems have some drawbacks. So we are going to develop new light control system which can overcome old systems drawbacks. We surveyed various street light control systems and analyzed its characteristics. Through these efforts, we found that common drawbacks of most light control systems are uneasiness of handling and difficulty of maintenance. To reduce uneasiness of handling and difficulty of maintenance in operating light control system, we designed new street light control system by using Zigbee communication technique. In this thesis, we describe on the H/W design of new street light control system designed by using Zigbee communication protocol.

• Communications of the Korean Mathematical Society
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• v.12 no.2
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• pp.427-456
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• 1997

This paper concerns constructing wavelet bases on the unit interval, where a new boundary treatment is provided to overcome certain drawbacks of eariler constructions. Wavelet expansions on the unit interval usually suffer from artificial boundary effects and poor convergence at the boundaries. Many researchers have suggested a solution to the drawbacks. From a practical point of view, their solutions also have a common disadvantage. This paper provides a new solution using biorthogonality near the boundaries, that avoids the disadvantage while preserving their advantages.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.1
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• pp.72-75
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• 2006

Event trees are widely used graphical tool to denote the accident inintiation and escalation to more severe accident. But they have some drawbacks in that they do not have efficient way of updating model parameters and also they can not contain the information about dependency or independency among model parameters. A tool that can cure such drawbacks is an influence diagram. We introduce influence diagrams and explain how to update model parameters and obtain predictive distributions. We show that an event tree can be converted to a statistically equivalent influence diagram, and bayesian prediction can be made more effectively through the use of influence diagrams.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.172-178
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• 2003

In the recent researches, a variety of ways for determining the locations of RBF centers have been proposed assuming that the number of RBF centers is known. But they have also many numerical drawbacks. We propose a new method to overcome such drawbacks. The strength of our method is to determine the locations and the number of RBF centers at the same time without any assumption about the number of RBF centers. The proposed method consists of two phases. The first phase is to determine the number and the locations of RBF centers using bi-section search method and enhanced k-medoids clustering which overcomes drawbacks of clustering algorithm. In the second phase, network weights are computed and the design of RBF network is completed. This new method is applied to several benchmark data sets. Benchmark results show that the proposed method is competitive with the previously reported approaches for center selection.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.4
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• pp.21-30
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• 2016

In a single-phase power factor correction (PFC), the standard cascaded control algorithm using a proportional-integral-derivative (PID) controller has two main drawbacks: an inability to track sinusoidal current reference and low harmonic compensation capability. These drawbacks cause poor power factor and high harmonics in grid current. To improve these drawbacks, this paper uses a proportional-integral-derivative-resonant (PIDR) controller which combines a type-III PID with proportional-resonant (PR) controllers in the PFC. Based on a small signal model of the PFC, the type-III PID controller was implemented taking into account the bandwidth and phase margin of the PFC system. To adopt the PR controllers, the spectrum of inductor current of the PFC was analyzed in frequency domain. The hybrid PIDR controller were simulated using PSCAD/EMTDC and implemented on a 3 kW PFC prototype hardware. The performance results of the hybrid PIDR controller were compared with those of an individual type-III PID controller. Both controllers were implemented successfully in the single-phase PFC. The total harmonic distortion of the proposed controller were much better than those of the individual type-III PID controller.

• Convergence Security Journal
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• v.18 no.2
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• pp.11-17
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• 2018

Lamport's one-time password (OTP) was originally proposed to address the weaknesses of a simple password system: fixed password, pre-shared password. However, a main weakness of Lamport's OTP is that a root hash value of a new hash chain should be re-registered after consuming all the hash values since OTP generation is based on the finite hash chain. Several studies have been conducted to solve these drawbacks, but new drawbacks such as increased burden of proof for verifiers and verifiers have been exposed. In this paper, we propose and compare a novel OTP that overlaps several short hash chains instead of one long hash chain, which is the core of existing Lamport OTP, to solve the drawbacks while maintaining the advantages of Lamport.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.119-130
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• 2023

Among the various elements of probabilistic safety assessment (PSA), human failure events (HFEs) and their dependencies are major contributors to the quantification of risk of a nuclear power plant. Currently, the dependency among HFEs is reflected using a post-processing method in PSA, wherein several drawbacks, such as limited propagation of minimal cutsets through the fault tree and improper truncation of minimal cutsets exist. In this paper, we propose a method to model the HFE dependency directly in a fault tree using the if-then-else logic. The proposed method proved to be equivalent to the conventional post-processing method while addressing the drawbacks of the latter. We also developed a software tool to facilitate the implementation of the proposed method considering the need for modeling the dependency between multiple HFEs. We applied the proposed method to a specific case to demonstrate the drawbacks of the conventional post-processing method and the advantages of the proposed method. When applied appropriately under specific conditions, the direct fault-tree modeling of HFE dependency enhances the accuracy of the risk quantification and facilitates the analysis of minimal cutsets.