• 대한원격탐사학회지
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• 제7권1호
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• pp.45-67
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• 1991

An overview is given on stochastic techniques with which remotely sensed data may be used together with ground measurements for purposes of state estimation and prediction. They can explicitly account for spatiotemporal differences in measurement characteristics between ground measurements and remotely sensed data, and are suitable for highly variant space or space-time processes, such as atmosperic processes, which may be viewed as (containing) a random process. For state estimation of static ststems, optimal linear estimation is described. As alternatives, various co-kriging estimation techniques are also described, including simple, ordinary, universal, lognormal, disjunctive, indicator, and Bayesian extersion to simple and lognormal. For illustrative purposes, very simple examples of optimal linear estimation and simple co-kriging are given. For state estimation and prediction of dynamic system, distributed-parameter kalman filter is described. Issues concerning actual implemention are given, and with application potential are described.

• 한국통신학회논문지
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• 제37권3A호
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• pp.163-171
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• 2012

IEEE802.15.4a 표준 채널 환경에 적합한 신호모형과 평균가중 도착각 추정기법을 제안하여 저속 초광대역 방식에 근거한 무선측위 시스템에 사용되는 신호 클러스터의 도착각 매개변수를 추정하고, 종래 추정방식들과 비교해 추정성능이 우수한 두 가지 방식을 제안한다. 클러스터 수가 많은 채널 환경에서는 평균 주사벡터기반의 도착각 추정방식이, 클러스터 수가 작은 채널에서는 평균가중 주사벡터 방식의 도착각 추정이 더 정확함을 컴퓨터 모의실험을 통해 보인다. 또한, 신호대 잡음비를 변화시켜도 항상 제안 방식의 성능이 우수함을 알 수 있으며, 제안 방식은 신호대 잡음비가 증가함에 따라 추정오차가 감소함도 알 수 있다.

• Journal of Information Processing Systems
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• 제8권4호
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• pp.621-652
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• 2012

Software Estimations provide an inclusive set of directives for software project developers, project managers, and the management in order to produce more realistic estimates based on deficient, uncertain, and noisy data. A range of estimation models are being explored in the industry, as well as in academia, for research purposes but choosing the best model is quite intricate. Estimation by Analogy (EbA) is a form of case based reasoning, which uses fuzzy logic, grey system theory or machine-learning techniques, etc. for optimization. This research compares the estimation accuracy of some conventional data mining models with a hybrid model. Different data mining models are under consideration, including linear regression models like the ordinary least square and ridge regression, and nonlinear models like neural networks, support vector machines, and multivariate adaptive regression splines, etc. A precise and comprehensible predictive model based on the integration of GRA and regression has been introduced and compared. Empirical results have shown that regression when used with GRA gives outstanding results; indicating that the methodology has great potential and can be used as a candidate approach for software effort estimation.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제5권
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• pp.493-502
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• 1997

An estimation method for groundwater level elevations is introduced. Using geostatistical techniques and anisotropies, experimental variograms show significant improved correlations compared with those from conventional techniques.

• 대한수학회지
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• 제34권4호
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• pp.927-947
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• 1997

A practical estimation method for groundwater level elevations is introduced. Using geostatistical techniques with drift, averaging process and ratio, experimental variograms show significant improved coorelation compared with those from conventional techniques. The estimation method is applied to a field experimental data set.

• 한국통신학회논문지
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• 제36권4C호
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• pp.207-216
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• 2011

움직임 보상 외삽 기법은 움직임 보상 보간 기법에 비해서 과거의 프레임만 사용하기 때문에 성능은 다소 떨어지지만, 전송 중에 손상된 프레임의 복원 및 프레임율 증가 뿐 아니라 분산 동영상 부호화 시스템의 부가 정보 생성에도 활용될 수 있다. 본 논문에서는 다양한 움직임 보상 외삽 기법의 성능을 평가하고 순방향과 역방향 움직임 추정을 함께 이용한 효율적인 움직임 보상 외삽 기법을 제안한다. 제안하는 기법은 순방향과 역방향 움직임 추정을 통해 두 개의 프레임을 생성하여 두 프레임의 화소값의 평균을 현재 프레임으로 한다. 모의 실험 결과 제안하는 기법이 기존의 기법에 비해서 블록 현상이 감소하고 우수한 PSNR 성능을 보임을 확인하였다.

• Journal of Oral Medicine and Pain
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• 제39권4호
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• pp.119-126
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• 2014

This review provides an overview of the most commonly used dental age estimation techniques which focus on radiological methods in Korean adults. The literature from 1995 through July 31, 2014, was searched, using PubMed, for publications in English language. In PubMed, the keywords 'tooth' OR 'dental' AND 'pulp' AND 'age estimation' were searched. Inclusion criteria was comprised of the following: the subjects were living adults and dental radiography (excluded computed tomography [CT] and cone-beam CT) was used to measure the pulpal size. Twenty articles that met the criteria were selected. The method of age estimation using dental radiographs for measuring pulp and tooth size was represented in all studies. The methods were assorted into three categories generally; Kvaal's, Ikeda's and Cameriere's methods. Those methods had certain limitations such as large error range and low correlation coefficient depending on populations, type of employed teeth and particular method. Various techniques and many studies have been published for age estimation from human teeth using dental radiographs, but those techniques showed various predictability and reliability. Therefore, future studies on larger samples with well-distributed age group using not only existing techniques but new techniques are necessary for deriving convincing results.

• 한국통신학회논문지
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• 제32권8A호
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• pp.813-819
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• 2007

본 논문에서는 트랜스패런트(transparent) 모바일 다중 홉 릴레이(Mobile Multi-hop Relay; MMR)를 갖는 OFDM 기반 셀룰러 시스템에서 발생하는 전파 지연(propagation delay)의 영향을 분석한다. 또한, 수율 상승(throughput enhancement; TE) 또는 상호협력 전송(cooperative transmission)을 위한 MMR을 갖는 OFDM 시스템에서 전파 지연에 대한 영향을 극복할 수 있는 LS 채널 추정 기법과 MMSE 채널 추정 기법을 제안한다. 본 논문에서 제안하는 채널 추정 기법은 TE MMR 시스템 또는 상호협력 MMR 시스템에서 전파 지연으로 인한 채널 추정 성능 열화 현상을 극복할 수 있다. 모의실험을 통해 MSE와 BER 측면에서 본 논문에서 제안하는 기법이 기존 기법보다 우수함을 보인다.

• 한국통신학회논문지
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• 제40권7호
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• pp.1239-1247
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• 2015

Frequency-division duplex (FDD) massive multiple-input multiple-output (MIMO) 시스템에서 하향 링크 채널 추정의 계산 복잡도는 기지국의 안테나 개수와 비례한다. 그러므로 이러한 시스템에서의 효율적인 채널 추정 방식이 연구 될 필요가 있다. 본 논문에서는 채널이 시간적, 공간적 상관관계를 가지는 모델에서 Kalman 필터와 least mean square (LMS) 등과 같은 적응 신호처리 기법을 이용한 채널 추정 방식을 제안한다.

• 전자공학회논문지B
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• 제30B권4호
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• pp.104-115
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• 1993

The motion compensated coding (MCC) technique, which exploits the temporal redundancies in the moving images with the motion estimation technique,is one of the most popular techniques currently used. Recently, a variable block size(VBS) motion estimation scheme has been utilized to improve the performance of the motion compensted coding. This scheme allows large blocks to the used when smaller blocks provide little gain, saving rates for areas containing more complex motion. Hence, a new VBS motion estimation scheme with a hierarchical structure is proposed in this paper, in order to combine the motion vector coding technique efficiently. Topmost level motion vector, which is obtained by the gain/cost motion estimation technique with selective motion prediction method, is always transmitted. Thus, the hierarchical VBS motion estimation scheme can efficiently exploit the redundancies among neighboring motion vectors, providing an efficient motion vector encoding scheme. Also, a restricted search with respect to the topmost level motion vector enables more flexible and efficient motion estimation for the remaining lower level blocks. Computer simulations on the high resolution image sequence show that, the VBS motion estimation scheme provides a performance improvement of 0.6~0.7 dB, in terms of PSNR, compared to the fixed block size motion estimation scheme.