• Journal of the Korean Data and Information Science Society
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• 제12권1호
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• pp.11-18
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• 2001

다구찌가 제안한 파라미터 설계는 제품설계나 공정설계 단계에서 품질특성치의 수행변동(performance variation)을 줄이는데 있다. 파라미터 설계에서 품질평균 근처에서 품질의 변동을 줄일 수 있는 최적조건을 찾는데 있어서 신호대 잡음비(Signal-to-noise ratio; SN비)라는 수행측도(performance measure)를 사용하였다. 그러나 많은 통계학자들은 SN비를 이용한 다구찌 분석 기법을 비판한다. 본 논문에서는 파라미터 설계를 위한 최적조건을 찾는데 있어서 SN비를 사용하지 않는 보다 실질적인 최적방안을 제안한다.

• 통상정보연구
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• 제10권2호
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• pp.349-369
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• 2008

The purpose of this study was to investigate the impact of the performance of small and medium companies located in Chungbuk according to their export ratio. First, there were significant the differences in those companies' performance depending on their export ratio. Such variables as operating incomes, current ratio, R&D, and the number of employees showed differences when those companies were divided into two groups whose export ratio were less than and more than 10%. Second, the impact of determinants which consisted of the size of total assets, R&D, advertisement, and export ratio on those companies' performance which consisted of profitability, stability, productivity, growth, liquidity, and activity was analyzed.

• KIEE International Transactions on Power Engineering
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• 제3A권2호
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• pp.70-78
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• 2003

This paper describes a transformer protection relay based on induced voltages. The ratio of the induced voltages of the primary and secondary windings is equal to the turns ratio during normal operating conditions such as magnetic inrush, overexcitation, and steady state, but it differs from the turns ratio in the case of internal faults. For a single-phase and a three-phase Y-Y transformer, the induced voltages are estimated and the ratios are compared with the turns ratio. For three-phase Y-Δ transformers, the differences between the induced voltages are estimated to use the line currents because delta-winding currents are practically unavailable. The proposed relay is tested under various conditions such as magnetic inrush, internal winding faults, overexcitation, and different core characteristics. The results evidently indicate that the relay successfully discriminates internal faults from magnetic inrush and overexcitation. This paper concludes by implementing the relay into a TMS320C6701 digital signal processor and reports satisfactory results. The relay requires no hysteresis data and can reduce the operating time of a relay.

• 디지털산업정보학회논문지
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• 제18권1호
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• pp.25-35
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• 2022

The SAP(salt-and-pepper) noise changes the pixel value to the maximum and minimum values of the dynamic region of the pixel. For this reason, unlike white Gaussian noise, SAP noise can predict the ratio of noise relatively easily. Because the condition of the neighboring pixels that can be referenced changes according to the noise ratio, it is necessary to apply different noise reduction methods according to the noise ratio. This paper proposes an adaptive switching filtering algorithm which can eliminates the SAP noise. It consists of two phases. It first detects the location of the SAP noise and calculates the noise ratio. After that, the image is reconstructed using different methods depending on which of the three sections the calculated noise ratio belongs to. As a result of the experiment, the proposed method showed superior objective and subjective image quality compared to the previous methods such as MF, AFSWMF, NAMF and RWMF.

• 지적과 국토정보
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• 제44권2호
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• pp.113-124
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• 2014

최근 집중호우에 의한 산사태 발생이 빈번해짐에 따라 산사태 취약지역을 분석하고 산사태 발생을 예측하기 위한 다양한 연구들이 진행되고 있다. 본 연구에서는 산사태 발생지역의 토양특성을 분석하였으며, 배수 특성별 우도비를 평가한 결과 배수가 좋은 토양에서 산사태 발생 가능성이 높게 나타났다. 또한 DEM 자료에서 추출한 경사도의 우도비를 평가한 결과 $20{\sim}40^{\circ}$ 경사구간에서 산사태 발생 가능성이 높게 나타났다. 그리고 공간분석에 의한 사면방향도의 우도비를 평가한 결과 북향에서 산사태 발생 가능성이 높게 나타났다. 아울러 토양배수, 경사도 그리고 사면방향도의 우도비를 중첩하여 산사태 취약도를 평가할 수 있었으며, 산사태 발생지역에 대하여 분석과 검증 프로세스를 수행함으로써 미래 산사태 발생 예측비율을 평가할 수 있었다.

• Journal of the Korean Data and Information Science Society
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• 제23권1호
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• pp.89-98
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• 2012

이 논문에서는 두 개의 Maxwell분포의 모수들의 동질성을 모수비에 근거하여 검정하는 근사통계량을 제안한다. Maxwell분포의 모수비에 대한 추정량이 복잡하여 정확한 분포를 유도하기는 매우 어렵다. 이러한 문제를 해결하기 위한 하나의 대안으로 표준정규분포로 근사적으로 수렴하는 통계량을 고려해야 한다. 이 논문에서 제안된 통계량은 표준정규분포로 수렴하며, 표본의 수가 작은 경우에도 사용할 수 있다. 특히, 본 논문에서는 부호화 로그 우도비 통계량과 수정된 부호화 로그 우도비 통계량을 개발한다. 일반적으로, 수정된 부호화 로그 우도비 통계량은 로그 우도비 통계량에 비해 표준정규분포로 수렴하는 속도가 매우 빠르다. 부호화 로그 우도비 통계량은 작은 표본으로도 표준정규분포로 매우 빨리 수렴한다. 제안된 통계량들의 성질들을 모의실험을 통하여 알아보고, 제안된 통계량을 예제를 통하여 연구한다.

• Journal of the Korean Data and Information Science Society
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• 제9권2호
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• pp.255-262
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• 1998

In this paper, we study the saddlepoint approximations for the ratio of independent random variables. In Section 2, we derive the saddlepoint approximation to the probability density function. In Section 3, we represent a numerical example which shows that the errors are small even for small sample size.

• Journal of the Korean Data and Information Science Society
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• 제7권2호
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• pp.289-294
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• 1996

This paper considers the limit of the ratio of two incomplete beta functions $I_{x}(p+s,q+r)\;to\;I_{x}(p,q)\;as\;p+q{\rightarrow}{\infty}$. The results show that the limits depend on r,s,x and the limit of p/(p+q).

• ETRI Journal
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• 제37권2호
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• pp.338-347
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• 2015

The multi-carrier transmission signal in Multi-Carrier Code Division Multiple Access (MC-CDMA) has a high peak-to-average power ratio (PAPR), which results in nonlinear distortion and deteriorative system performance. An n-tuple selective mapping method is proposed to reduce the PAPR, in this paper. This method generates $2^n$ sequences of an original data sequence by adding n-tuple of n PAPR control bits to it followed by an interleaver and error-control code (ECC) to reduce its PAPR. The convolutional, Golay, and Hamming codes are used as ECCs in the proposed scheme. The proposed method uses different numbers of the n PAPR control bits to accomplish a noteworthy PAPR reduction and also avoids the need for a side-information transmission. The simulation results authenticate the effectiveness of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.628-646
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• 2016

This paper proposes a novel channel assignment scheme that is based on finite projective plane (FPP) theory. The proposed scheme involves using a Markov chain model to allocate N channels to N users through intermixed channel group arrangements, particularly when channel resources are idle because of inefficient use. The intermixed FPP-based channel group arrangements successfully related Markov chain modeling to punch through ratio formulations proposed in this study, ensuring fair resource use among users. The simulation results for the proposed FPP scheme clearly revealed that the defined throughput increased, particularly under light traffic load conditions. Nevertheless, if the proposed scheme is combined with successive interference cancellation techniques, considerably higher throughput is predicted, even under heavy traffic load conditions.