• 한국통신학회논문지
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• 제37권6A호
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• pp.438-449
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• 2012

본 논문에서는 다양한 CRC 코드의 성능분석을 기반으로 새로운 VHF 대역 해양 무선통신용 최적 CRC-p 코드를 제안한다. 이를 위해, 먼저 CRC 코드의 부호어 길이의 변화에 따른 미검출 오류확률과 최소해밍거리를 구하는 방법을 기술한다. 즉 순회 해밍코드나 원시 BCH 코드의 쌍대코드가 최대장 코드가 되는 것을 이용해서 천이 레지스터에 의한 간단한 회로구성으로 무게분포와 미검출 오류확률을 계산하는 방법과 MacWilliam의 항등식에 의한 최소해밍거리를 계산하는 방법을 제시한다. 다음으로 VHF 대역 해양 무선통신 시스템의 전송 프레임의 구성과 주요 통신 파라미터의 규격을 제시하고, 기존의 연구된 다양한 CRC 코드의 생성다항식을 대상으로 미검출 오류확률과 최소해밍거리의 결과를 기반으로 새로운 CRC-p 코드를 선정하고, 라이시안 해양 채널모델과 ${\pi}$/4-DQPSK 변복조기에 의한 비트오류율(BER)의 모의실험 결과를 통해 성능을 검증한다.

• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.42-47
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• 2004

This paper presents the various application programs for the Distribution Automation System (DAS) of the Korea Electric Power Corporation (KEPCO)'s distribution system. These programs are developed to allow for optimal operation in the areas of feeder automation, relay coordination, loss minimization and so on. They are single line diagram auto creation programs for the feeder, service restoration program, protection coordination program, data error detection program, and optimal network reconfiguration program. The details of these programs are presented for validity and effectiveness.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.441-450
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• 2004

The velocity distribution of gas molecules from the experimental results was confirmed as the same with the Maxwell-Boltzmann's theoretical results within the experimental error. This study is on the realization of the Maxwell-Boltzmann's velocity distribution of gas molecules by the molecular dynamics(MD) method. The Maxwell-Boltzmann's velocity distribution of gas molecules is extremely important to confirm the equilibrium state because the properties of a thermodynamic system shall be obtained from the system's equilibrium configuration in the MD method. This study is the first trial in the successive researches to calculate the properties of a thermodynamic system by the computer simulations. We confirmed that the maxwell-boltzmann's velocity distribution is developed in some transient time after starting a simulation and dependent on the size of a system. Also it is found that the velocity distribution has no relation with an initial configuration of gas molecules.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.213-217
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• 1998

This study overviews existing evaluation methods of classification accuracy using confusion matrix proposed by Cohen in 1960's, and proposes ISDd(Index of Spatial Distribution by distance) and ISDs(Index of Spatial Distribution by scatteredness) for the evaluation of spatial distribution of satellite image classification errors, which has not been tried yet. Index of spatial distribution offers the basis of decision on adoption/rejection of classification results at sub-image level by evaluation of distribution, such as status of local aggregation of misclassified pixels. So, users can understand the spatial distribution of misclassified pixels and, can have the basis of judgement of suitability and reliability of classification results.

• 한국전문물리치료학회지
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• 제23권2호
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• pp.93-99
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• 2016

Background: Parametric statistical procedures are typically conducted under the condition in which a sample distribution is statistically identical with its population. In reality, investigators use inferential statistics to estimate parameters based on the sample drawn because population distributions are unknown. The uncertainty of limited data from the sample such as lack of sample size may be a challenge in most rehabilitation studies. Objects: The purpose of this study is to review the bootstrapping method to overcome shortcomings of limited sample size in rehabilitation studies. Methods: Articles were reviewed. Results: Bootstrapping method is a statistical procedure that permits the iterative re-sampling with replacement from a sample when the population distribution is unknown. This statistical procedure is to enhance the representativeness of the population being studied and to determine estimates of the parameters when sample size are too limited to generalize the study outcome to target population. The bootstrapping method would overcome limitations such as type II error resulting from small sample sizes. An application on a typical data of a study represented how to deal with challenges of estimating a parameter from small sample size and enhance the uncertainty with optimal confidence intervals and levels. Conclusion: Bootstrapping method may be an effective statistical procedure reducing the standard error of population parameters under the condition requiring both acceptable confidence intervals and confidence level (i.e., p=.05).

• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.10-17
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• 2009

Accurate electroencephalography (EEG) forward calculation is of importance for the accurate estimation of neuronal electrical sources. Conventional studies concerning the EEG forward problems have investigated various factors influencing the forward solution accuracy, e.g. tissue conductivity values in head compartments, anisotropic conductivity distribution of a head model, tessellation patterns of boundary element models, the number of elements used for boundary/finite element method (BEM/FEM), and so on. In the present paper, we investigated the influence of modeling errors in the boundary element volume conductor models upon the accuracy of the EEG forward solutions. From our simulation results, we could confirm that accurate construction of boundary element models is one of the key factors in obtaining accurate EEG forward solutions from BEM. Among three boundaries (scalp, outer skull, and inner skull boundary), the solution errors originated from the modeling error in the scalp boundary were most significant. We found that the nonuniform error distribution on the scalp surface is closely related to the electrode configuration and the error distributions on the outer and inner skull boundaries have statistically meaningful similarity to the curvature distributions of the boundary surfaces. Our simulation results also demonstrated that the accumulation of small modeling errors could lead to considerable errors in the EEG source localization. It is expected that our finding can be a useful reference in generating boundary element head models.

• 응용통계연구
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• 제19권1호
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• pp.81-96
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• 2006

본 연구에서는 분포를 알 수 없고 비대칭인 공정자료에 실용적으로 적용할 수 있는 간단한 관리도법을 제안하였다. 비대칭 분포를 따르는 공정자료에 정규성 가정에 기초한 슈하르트 관리도를 그대로 적용하면 비대칭성이 증가할수록 제 1종 오류를 범할 확률이 증가할 가능성이 높아지며 변동을 관리하는데 효율성이 떨어지게 된다. 이러한 문제를 해결하기 위해 본 연구에서 제시한 관리도는 관리한계선을 사분위수에 기초하여 정하는 방안을 제시하고 있다. 이러한 방법으로 관리한계선을 그릴 경우 제 1종 오류도 감소하게 되고, 비대칭분포를 하는 공정자료에 대하여 매우 실용적이라고 하겠다.

• 소성∙가공
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• 제9권4호
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• pp.404-412
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• 2000

It is desirable to use the square grid analysis with the aid of the stereo vision and image processing techniques in order to automatically measure the surface-strain distribution over a stamped part. But this method has some inherent problems such as the difficulty in enhancement of bad images, the measurement error due to the digital image resolution and the limit of the area that can be measured at a time. Therefore, it is still hard to measure the strain distribution over the entire surface of a medium-or large-sized stamped part even by using an automated strain measurement system. In this study, several methods which enable to solve these problems considerably without losing accuracy and precision In measurement are suggested. The superposition of images that have different high-lightened or damaged part from each other gives much enhanced image. A new algorithm for constructing of the element connectivity from the line-thinned image helps recognize up to 1,000 elements. And the geometry assembling algorithm including the global error minimization makes it possible to measure a large specimen with reliability and efficiency.

• 한국측량학회지
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• 제32권3호
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• pp.225-231
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• 2014

When a spatial regression model that uses kernel density values as a dependent variable is applied to retail business data, a unique model cannot be selected because kernel density values change following kernel bandwidths. To overcome this problem, this paper suggests how to use the point pattern analysis, especially the L-index to select a unique spatial regression model. In this study, kernel density values of retail business are computed by the bandwidth, the distance of the maximum L-index and used as the dependent variable of spatial regression model. To test this procedure, we apply it to meeting room business data in Seoul, Korea. As a result, a spatial error model (SEM) is selected between two popular spatial regression models, a spatial lag model and a spatial error model. Also, a unique SEM based on the real distribution of retail business is selected. We confirm that there is a trade-off between the goodness of fit of the SEM and the real distribution of meeting room business over the bandwidth of maximum L-index.

• 한국통신학회논문지
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• 제16권12호
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• pp.1366-1381
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• 1991

톤간섭과 잡음 환경하에서 m-분포 페이딩 채널을 통해 수신되는 DS/QPSK 신호의 오율식을 유도한 후 이를 수치계산하여 그림으로 나타내어 검토했다. 오율식의 유도는 두 가지 경우에 대하여 행했다. 즉, 하나는 신호만 페이딩의 영향을 받는 경우이고 다른 하나는 신호와 간섭이 동시에 페이딩의 영향을 받는 경우이다. 수치 계산하여 얻어진 결과로부터 신호만 페이딩의 영향을 받는 경우보다 신호와 간섭이 동시에 페이딩의 영향을 받는 경웨 오율특성이 더 열화되는데 직접확산을 이용하면 큰 오율개선이 이루어진다는 것을 알수 있었다. 그러나 그 오율의 개선폭은 간섭과 페이딩의 영향이 약해지면 약해질수록 작아진다는 것을 확인할수 있었다.