• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.22-22
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• 2001

정보량이 많은 고화질의 동영상을 실시간으로 전송하기 위하여 압축 알고리즘을 필수적으로 사용하고 있으며, 시간적 중복성을 제거하는 동영상의 압축방법은 움직임 추정 알고리즘을 사용한다. 본 연구에서 설계하고자 하는 움직임 추정기는 블록정합 알고리즘이며, MPEG 부호기에서 사용되는 DCT 연산 결과인 DC 값을 이용하여 화면의 밝기를 판단한다. 움직임 추정기는 휘도 신호 8비트 모두를 사용하지 않고, 화면 밝기에 따른 비트 플레인(bit plane)에서 3비트만 선택하는 비교선택기를 이용한다. 본 연구에서 제안한 비교 선택기는 I-Picture만을 계산한다. I-Picture에 의해 계산된 선택 비트는 I, P와 B Picture의 움직임 추정 연산에 사용함으로서 움직임 추정기의 크기를 줄일 수 있는 구조를 제안하였다. 제안된 움직임 추정기의 고찰을 위하여 실험에 사용된 표준 동영상의 해상도는 352×288이며, DCT 연산의 처리 블록은 8×8이며, 탐색 영역은 23×23이다. 제안된 알고리즘은 C언어로 모델링하였으며, 기존 완전탐색방법과 PSNR을 비교한 결과 사람의 시각으로 거의 구별할 수 없는 작은 차이(0～0.83dB)가 나타남을 알 수 있었다. 본 연구에서 제안한 움직임 추정기의 하드웨어 크기는 기존 구조Ⅰ보다 38.3%, 기존 구조Ⅱ보다 30.7% 줄일 수 있었고, 메모리 크기는 기존 구조Ⅰ,Ⅱ보다 31.3% 줄일 수 있었다.

• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.533-540
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• 2020

A total length of sperm whales can be estimated by measuring the Inter-Pulse Interval(IPI) of their clicks composed by multiple pulses. The IPI is caused by the two-way travel time of the sound transmission in the spermaceti within the whale head. Therefore, the IPI can be used to measure the whale's total length based on allometric relationships between head and body length. In this paper, the click signals recorded in the East Sea, Korea in 2017 were analyzed to estimate the size of sperm whales. The size of sperm whales calculated by the relationship between IPI and body length was 9.9 m to 10.9 m, which is corresponding to the size of an adult female or a juvenile male sperm whale. This non-lethal acoustic method has been demonstrated to accurately estimate the sperm whale size, and can provide useful information for domestic sperm whale monitoring.

• The Korean Journal of Applied Statistics
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• v.33 no.3
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• pp.347-355
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• 2020

An Isolation-with-Migration (IM) model is used to estimate extant population sizes, the splitting time of populations split away from their common ancestral populations, and migration rates between the extant populations. An evolutionary model such as IM models is estimated by analyzing DNA sequences sampled from the extant populations in the model. When a true model includes an unsampled 'ghost' population without data, the unsampled population is often ignored from the evolutionary model to infer. In this paper, we conduct a simulation study to investigate the effect of an unsampled population on the estimation of the size of the sampled population. When there exists an unsampled population that shares migrations with the sampled population, the size estimation of the sampled population was biased. However, the size estimation was improved if an evolutionary model, including the unsampled population, was estimated.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.23-30
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• 2004

In order to approximate the spatial query result size we partition the input rectangles into subsets and estimate the query result size based on the partitioned spatial area. In this paper we examine query result size estimation in skewed data. We examine the existing spatial partitioning techniques such as equi-area and equi-count partitioning, which are analogous to the equi-width and equi-height histograms used in relational databases, and examine the other partitioning techniques based on spatial indexing. In this paper we propose a new spatial partitioning technique based on the Hilbert space filling curve. We present a detailed experimental evaluation comparing the proposed technique and the existing techniques using synthetic as well as real-life datasets. The experiments showed that the proposed partitioning technique based on the Hilbert space filling curve achieves better query result size estimation than the existing techniques for space query size, bucket numbers, skewed data, and spatial data size.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.320-329
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• 2021

In this paper, an empirical model of air bubble size to be applied to an air masker for reduction of underwater radiation noise is presented. The proposed model improves the divergence problem under the low-speed flow condition of the existing model derived using Rayleigh's jet instability model and simple continuity condition by introducing a jet flow velocity of air. The jet flow velocity of air is estimated using the bubble size where the liquid is quiescent. In a medium without flow, the size of the bubble is estimated by an empirical method where bubble formation regime is divided into a laminar-flow range, a transition range, and a turbulent-flow range based on the Reynolds number of the injected air. The proposed bubble size model is confirmed to be in good agreement with the Computational Fluid Dynamics (CFD) analysis result and the experimental results of the existing literature. Using the acoustic inversion method, the air bubble population is estimated from the insertion loss measured during the air injection experiment of the air- masker model in a large cavitation tunnel. The results of the experiments and the bubble size model are compared in the paper.

• The Korean Journal of Applied Statistics
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• v.11 no.2
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• pp.403-413
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• 1998

Sample size determination is a crucial part of sampling design. This paper gives a assessment for sample size determination using two-stage sampling scheme for estimating the population mean with a given precision.

• 한국데이터정보과학회:학술대회논문집
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• 2003.10a
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• pp.139-145
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• 2003

본 논문에서는 강수 자료의 예측에 사용되는 3-모수 카파 분포(KD3)에서의 모수 추정 방법을 알아보고 시뮬레이션을 통하여 모수 추정 방법에 따른 성능을 비교해 보았다. 이 분포의 모수 $\alpha,\;\beta,\;\mu$를 추정하기 위하여 적률추정법(MME), L-적률 추정법(LME), 최우추정법(MLE)을 적용하였다. 소표본의 경우뿐만 아니라 대표본의 경우에도 시뮬레이션을 통하여 추정법들의 성능을 비교하였다. 적률 추정법과 L-적률 추정법에서는 제약조건 하에서의 1차원 Newton-Raphson방법을 수정하여 이용하였다. MSE를 기준으로 한 시뮬레이션 결과, KD3의 모수 추정에 있어서 표본의 크기가 100보다 작으면 LME의 적용을 추천하고 표본의 크기가 100이상이면 MLE를 추천한다.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.1
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• pp.15-22
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• 2015

Estimating the number of distinct values is really well-known problems in network data measurement and many effective algorithms are suggested. Recent works have built upon technique called Linear Counting to solve the estimation problem for massive sets or spreaders in small memory. Sampling is used to reduce the measurement data, and it is assumed that sampling gives bad effect on the accuracy. In this paper, however, we show that the sampling on multi-set estimation sometimes gives better results for CSE with sampling than for MCSE that examines all the packets without sampling in terms of accuracy and estimation range. To prove this, we presented mathematical analysis, conducted experiment with real data, and compared the results of CSE, MCSE, and CSES.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.1-4
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• 2019

본 연구에서는 적외선 카메라 기반의 비접촉식 측정 방법을 이용하여 동공 반응 데이터를 수집하여 공감의 사회감성을 객관적이고 정량적으로 추정하는데 그 목적이 있다. 실험에는 10명(남 6명, 여 4명, M ± SD = 24.17 ± 2.16세)의 피험자가 참여하였다. 30초의 참조 데이터 측정 후, 공감 유무에 따라 과제는 얼굴 표정 모방 과제와 얼굴 표정 자발적 표현 과제로 구분되어 두 사람은 표정으로 상호작용하였고, 2번씩 반복 진행하며 적외선 카메라를 통해 동공을 촬영하였다. 이진화 및 원형 윤곽선 검출법의 영상처리를 활용하여 동공 데이터를 수집하였고, 이동 평균 기법을 활용해 눈깜빡임 노이즈를 제거하고 동공 크기 개인차로 데이터 표준화를 진행하였다. 공감 유무에 따른 동공 크기 데이터는 정규성 검증 및 독립표본 t검정을 통해 통계적 유의성을 확인하였다. 분석결과, 공감하는 경우(M ± SD = 0.508 ± 1.278)와 공감하지 않은 경우(M ± SD = 1.681 ± 0.968) 동공 크기가 통계적으로 유의미한 차이를 보였다(t(18) = -2.313, p = 0.033). 판별분석을 통해 동공 크기에 따른 공감의 유무를 추정하는 규칙을 정의하였다. 본 연구에서 제안한 동공 크기 데이터를 이용한 공감의 사회감성 추정 기술은 비접촉식 카메라 기반의 기술로 스마트 글래스와 접목되어 다양한 분야에 활용도가 높을 것으로 기대된다.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.916-924
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• 2014

It is possible to improve the accuracy of the motion estimation for a video by applying a variable block size. However, it has limits in the zoom motion estimation. In this paper, we propose a method for estimating the zoom motion with variable block size. The proposed method separates the background within the object picture by depth information obtained from a depth camera, and only the object regions are applied to zoom scale, but the background is not applied. In addition, the object regions select efficiently variable block size mode in consideration of the generated motion vectors and the accuracy of motion estimation at the same time. Simulation results show the accuracy of the motion estimation and the number of motion vectors for the proposed method. It is verified that the proposed method can reduce the number of motion while maintaining the similar accuracy of motion estimation than the conventional motion estimation methods.