• 한국측량학회지
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• 제8권2호
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• pp.35-43
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• 1990

본 논문은 2차원망조정이론을 정립하여 단열삼각망, 사변삼각망, 유심삼각망과 복합측지망의 각 평면 삼변망을 해석하였다. 이들 수평삼변망의 형태에 따른 오차전파식을 유도하여 오차특성을 해석하였고, 또한 복합측지망에서는 오차해석 결과를 오차타원으로 나타내었으며, Data Snooping 방법에 따른 과대오차검출을 시도하였다.

• Journal of Communications and Networks
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• 제9권4호
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• pp.466-472
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• 2007

Single carrier block transmission with frequency domain equalization(SC-FDE) has been shown to be a promising candidate in ultra-wideband(UWB) communications. In this paper, we analyze the performance of SC-FDE over UWB communications with channel estimation error. The probability density functions of the frequency domain minimum mean-squared error(MMSE) equalizer taps are derived in closed form. The error probabilities of single carrier block transmission with frequency domain MMSE equalization under imperfect channel estimation are presented and evaluated numerically. Compared with the simulation results, our semi-analytical analysis yields fairly accurate bit error rate performance, thus validating the use of the Gaussian approximation method in the performance analysis of the SC-FDE system with channel estimation error.

• 응용통계연구
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• 제6권2호
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• pp.303-309
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• 1993

오차에 대한 함수관계식이 불확실한 경우 두가지 실험계획법을 제시하였다. 하나는 모든 가능한 오차함수식을 대상으로 최저의 효율성을 높이는 방안이고 다른 하나는 확률을 이용한 최저의 평균효율성을 높이는 방안이다. 이러한 두 방법을 D-와 이분산 G-최적성에 적응시켜 그 차이점을 비교연구하였다.

• Journal of Information Technology Applications and Management
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• 제27권3호
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• pp.69-75
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• 2020

In this paper, we applied the shape parameters of the exponentialized exponential life distribution widely used in the field of software reliability, and compared the reliability properties of the software using the non-homogeneous Poisson process in finite failure. In addition, the average value function is also a non-decreasing form. In the case of the larger the shape parameter, the smaller the estimated error in predicting the predicted value in comparison with the true value, so it can be regarded as an efficient model in terms of relative accuracy. Also, in the larger the shape parameter, the larger the estimated value of the coefficient of determination, which can be regarded as an efficient model in terms of suitability. So. the larger the shape parameter model can be regarded as an efficient model in terms of goodness-of-fit. In the form of the reliability function, it gradually appears as a non-increasing pattern and the higher the shape parameter, the lower it is as the mission time elapses. Through this study, software operators can use the pattern of mean square error, mean value, and hazard function as a basic guideline for exploring software failures.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.40-52
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• 2020

In this paper, we consider a precoder design problem for multiuser interference channel. Most of the conventional schemes for precoder design utilize a signal-to-interference-plus-noise ratio (SINR) as a cost function. However, since the SINR metric of a desired transmitter-receiver pair is a function of precoding vectors of all transmitters in the multiuser interference channel, an analytic closed-form solution is not available for the precoding vector of a desired transmitter that maximizes the SINR metric. To eliminate coupling between the precoding vectors of all transmitters and to find a closed-form solution for the precoding vector of the desired transmitter, we use a signal-to-leakage-plus-noise ratio (SLNR) instead as a cost function because the SLNR at a transmitter is a function of the precoding vector of the desired transmitter only. In addition, channel estimation errors for undesired links are considered when designing the precoding vector because they are inevitable in a multiuser interference channel. In this case, we propose a design scheme for the precoding vector that is robust to the channel estimation error. In the proposed scheme, the precoding vector is designed to maximize the worst-case SLNR. Through computer simulation, we show that the proposed scheme has better performance than the conventional scheme in terms of SLNR, SINR, and sum rate of all users.

• 한국정밀공학회지
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• 제19권5호
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• pp.56-63
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• 2002

A new model utilizing a transfer function is introduced in the present paper for analizing motion errors of hydrostatic tables. Relationship between film reaction force in a single hydrostatic pad and form error of a guide rail is derived at various spacial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so called averaging effect of the oil film quantitively. For example, it is found that the amplitide of the film reaction farce is reduced as the spacial frequency increases or relative width of the pocket is reduced. Motion errors of a multiple pad table is estimated from transfer function, geomatric relationship between each pads and form errors of a guide rail, which is named as Transfer Function Method(TFM). Calculated motion errors by TFM show good agreement with motion errors calculated by Multi Pad Method, which is considered entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.

• International Journal of Precision Engineering and Manufacturing
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• 제4권2호
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• pp.64-70
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• 2003

A new method using a transfer function is introduced in the present paper for analyzing the motion errors of hydrostatic bearing tables. The relationship between film reaction force in a single-side hydrostatic pad and the form error of guide rail is derived at various spatial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so called 'the averaging effect of an oil film' quantitively. It is found that the amplitude of film force is reduced as the spatial frequency increases or the relative width of the pocket is reduced. The motion errors of a multi pad type table are estimated using a transfer function, the form errors of a guide rail and the geometric relationship between the pads. The method is named as the Transfer Function Method (TFM). The motion errors calculated by the TFM show good agreement with the motion errors calculated by the Multi Pad Method considering the entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.

• International Journal of Precision Engineering and Manufacturing
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• 제4권2호
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• pp.57-63
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• 2003

A new method using a transfer function was proposed in the previous paper for analyzing motion errors of hydrostatic tables. The calculated motion errors by the new method, named as the transfer (unction method (TFM), were compared with the results by the conventional multi pad method, and the validity of the proposed method was theoretically verified. In this paper, the relationship between rail form error and motion errors of a hydrostatic table is examined theoretically in order to comprehand so-called 'the averaging effect of an oil film', and the characteristics of the motion errors in a hydrostatic table is tested. The tested hydrostatic table has three single-side pads in the vertical direction and three pairs of double-sides pads in the horizontal direction. The motion errors are tested for three rails which have different form errors. The experimental results are compared with the theoretical results calculated by the TFM, and both results show good agreement. From the results, it is shown that the TFM is very effective to analyze the motion errors of hydrostatic tables.

• 한국통신학회논문지
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• 제28권11C호
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• pp.1070-1076
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• 2003

이 논문에서는 주파수 비 선택적 m분포 나카가미 페이딩 채널에서 정방형 M-QAM 신호에 대하여 MRC 다이버시티 적용시 정확하고 일반화된 평균 비트 에러 확률식을 closed-form으로 유도하고 성능을 분석한다. 독립된 페이딩 환경과 상관된 페이딩 환경에 대하여 각각 L개의 브랜치를 가지는 MRC 다이버시티를 고려하며. 성능 분석을 통하여 에러 성능이 향상됨을 보인다. 이 논문에서 제시되는 새로운 비트 에러 확률 식들은 이동 통신의 페이딩 채널에서 MRC 다이버시티가 적용된 임의의 정방형 M-QAM 신호에 대한 성능을 계산하고 분석하는데 유용한 방법을 제공한다.

• 한국통신학회논문지
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• 제36권7C호
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• pp.451-458
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• 2011

MAXFLAT(maximally flat) FIR필터 설계는 폐쇄형 솔루션을 제공하는 장점이 있으나 설계의 정확성을 위하여 평탄차수를 정확하고 효율적으로 결정하는 문제가 아직 남아 있다. 본 논문에서는 폐쇄형 솔루션에서 주파수영역 오차함수를 모델링하고 분석하므로 써 직접적이고 정확하게 평탄차수를 결정하는 방법을 제안하였다. 마지막으로 주피수영역 오차함수를 바탕으로 제안한 차단주파수와의 최소거리 방식이 기존의 Herrmann 방식에 비해 매우 정확하고 효율적이라는 것을 입증하였다.