• 품질경영학회지
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• 제27권4호
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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.

• 한국전자거래학회:학술대회논문집
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• 한국전자거래학회 1998년도 학술대회지 vol.2
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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.

• 한국지능시스템학회논문지
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• 제19권1호
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• pp.102-107
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• 2009

Fuzzy C-Means(FCM)의 단점을 극복하기 위해 제안되었던 PCM은 잡음에는 강하지만 초기 파라미터 값에 민감하고, 상대적으로 가까이에 위치한 prototype들을 형성하는 패턴들의 경우에는 최종 prototype의 위치가 겹치는(동일한) 결과가 나올 수 있다는 단점이 있다. 이러한 PCM의 단점을 극복하기 위해 여러 방법이 제안되었지만, 본 논문에서는 PCM 알고리즘에 Interval Type 2 Fuzzy 접근 방법을 적용하여 PCM 알고리즘의 파라미터에 존재하는 uncertainty를 제어함으로써 성능을 향상시키는 방법을 제안한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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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.

• 대한수학회논문집
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• 제12권2호
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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.

• 산업경영시스템학회지
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• 제29권1호
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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.

• 대한산업공학회지
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• 제29권2호
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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.

• 한국산업정보학회논문지
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• 제21권4호
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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.

• 융합보안논문지
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• 제18권2호
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• pp.11-17
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• 2018

Lamport 일회용 패스워드(OTP)는 고정된 패스워드 그리고 패스워드의 사전공유라는 단순 패스워드가 지니는 문제점을 해결하기 위해 해시체인에 기반을 두고 있다. 하지만 Lamport 방식은 길이가 유한한 해시체인의 해시값을 OTP로 사용하기 때문에 해시체인을 구성하는 해시값들을 모두 소진한 이후에는 새로운 해시체인의 루트 해시값을 재 등록해야 한다는 단점을 가지고 있다. 이 같은 단점을 해결하기 위해 여러 연구가 진행되었으나 증명자와 검증자에 대한 계산 부담이 증가하는 등 새로운 단점이 노출되었다. 따라서 본 논문에서는 Lamport 방식의 장점을 유지하면서 동시에 단점을 해결하기 위해 기존 Lamport 방식 OTP의 핵심인 하나의 긴 해시체인 대신에 여러 개의 짧은 해시체인을 중첩 구성하는 새로운 방식의 OTP를 제안하고 비교 분석한다.

• Nuclear Engineering and Technology
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• 제55권1호
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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.