• 한국통신학회논문지
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• 제30권5A
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• pp.370-375
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• 2005

인터넷 및 통신망 국제표준 단체들은 자신들의 망에서 서비스 품질 보장형 기능을 제공하기 위한 방안으로써 공통적으로 리키버킷에 의한 입력 트래픽 정의 방법을 채택하고 있다. 반면, 그동안 연구결과는 멀티미디어 트래픽의 버스트특성이 시간적으로 광범위한 준위에 걸쳐 있음을 확인하고 있다. 이러한 두개의 상반되는 현실을 해결하기 위하여 본 논문에서는 임계 시준위 개념을 사용한 표준적 트래픽 기술자계산 방법을 제안하고 이를 시뮬레이션을 통하여 분석하였다. 제안된 알고리듬은 지연치가 주어진 상태에서 최상의 성능을 얻음을 수학적으로 증명하였고, 실제 시스템 응용에 대하여 제안하였다.

• 대한원격탐사학회지
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• 제17권2호
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• pp.183-188
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• 2001

The NOAA AVHRR remotely sensed SST data, collected by the National Fisheries Research and Development Institute (NFRDI), are analyzed in order to understand the spatial and temporal distributions of SST in the sea near korea. Our study is based on 10-day SST images during last 7 years (1991-1997). For a time series analysis of multiple SST images, all of images must be consistent exactly at the same position by adjusting the scales and positions of each SST image. We devised an algorithm which automatically detects cloud pixels from multiple SST images. The cloud detection algorithm is based on a physical constraint that SST anomalies in the ocean do not exceed certain limits (we used $\pm$3$^{\circ}C$ as a criterion of SST anomalies). The remotely sensed SST data are tuned by comparing remotely sensed data with observed SST at coastal stations. Seasonal variations of SST are studied by harmonic fit of SST normals at each pixel and the SST anomalies are studied by statistical method. It was found that the SST anomalies are rather persistent for one or two months. Utilizing the persistency of SST anomalies, we devised an algorithm for a prediction of future SST. In the Markov lprocess model of SST anomalies, autoregression coefficients of SST anomalies during a time elapse of 10 days are between 0.5 and 0.7. The developed algorithm with automatic cloud pixel detection and rediction of future SST is expected to be incorporated to the operational real time service of SST around Korea.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2002년도 창립 20주년기념 국제학술대회
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• pp.25-33
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• 2002

Historical maps are precious materials, which show spatial distribution of land use, streets and so on at the time when the maps were produced. In analysis of historical maps, the most practical method is to compare them with the present ones, for instance by overlaying them. However, the low precision, in the geometrical sense, of the historical maps makes the task of comparison very difficult. This drawback brings us the idea to incorporate the historical maps into GIS after rubber-sheet transformation, i.e. geometric correction, of them. It makes comparing and overlaying multiple maps from different time periods. Furthermore, it gives map-scales to the historical maps, which are not in general represented on the old maps, and if we allow ourselves to ignore the changes in terrain from past to present, it will make overlaying of present contour lines on the historical maps. As a result, we can bring the points of view of quantitative consideration and three-dimensional visualization into analyses of historical map. We have addressed incorporating historical maps produced in Edo period (1603-1867) in Japan into our GIS for Tokyo. This article shows the outline of our procedures and some applications, e.g., overlaying different maps from Edo period to present, quantitative analyses of land use in Edo, and visualization of landscape of Edo.

• 천문학회보
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• 제39권2호
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• pp.57.1-57.1
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• 2014

We present results of our investigation of intrinsic brightness temperatures of compact radio jets at radio frequencies. The intrinsic brightness temperatures of about 100 compact radio jets at 2, 5, 8, 15, and 86 GHz are estimated based on large VLBI surveys conducted in 2001-2003 (or in 1996 for the 5 GHz sample). The multi-freqeuncy intrinsic brightness temperatures of the sample of the jets are determined with a statistical method relating the observed brightness temperatures with the maximal apparent jet speed, assuming one representative intrinsic brightness temperature for the sample at each observing frequency. With investigating the observed brightness temperatures at 15 GHz in multiple epochs, we found that the determination of the intrinsc brightness temperature for our sample is affected by variability of individual jets in flux density at the time scales of a few years. This implies an importance of contemporaneity of the multi-frequency VLBI observations for the statistical method. Since our analysis is based on the VLBI observations conducted in 2001-2003, the results are less affected by the flux density variability. We found that the intrinsic brightness temperature $T_0$ increases as $T_0{\propto}{\nu}^{\epsilon}$ with ${\epsilon}{\approx}0.7$ below a critical frequency ${\nu}_c{\approx}10GHz$ where energy losses begin to dominate the emission, and above the critical frequency, $T_0$ decreases with ${\epsilon}{\approx}-1.2$ supporting for the decelerating jet model.

• 대한전자공학회논문지SP
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• 제39권2호
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• pp.1-10
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• 2002

이 논문에서는 크기와 영상 평면상에서 회전 (in-plane rotation) 변화를 가지는 정면 얼굴 영상의 인식성능을 향상시키기 위하여, 새로운 템플릿 (template) 기반 접근 방법들을 제안한다. 인식 성능을 향상시키기 위한 템플릿들은 크기와 회전 변화가 다른 다수의 영상들을 선형 또는 비선형 연산에 의하여 생성된다. 얼굴의 크기와 영상 평면에서 회전 변화에 무관한 얼굴의 특징을 추출하기 위하여 어파인 (affine) 변환, 로그폴라 (log-polar) 사상, 그리고 로그폴라 영상에 기반한 FFT들이 이용된다. 제안된 방법들은 인식률과 수행 시간 측면에서 비교된다. 실험 결과로부터 제안된 템플릿을 이용한 방법들의 인식률이 한 장의 영상으로 생성된 템플릿을 이용한 방법들의 인식률보다 우수함을 나타낸다. 어파인 변환을 이용한 방법의 인식률이 로그폴라 사상을 이용한 방법과 로그폴라 영상에 기반한 FFT 방법의 인식률보다 우수하며, 수행 시간 측면에서는 로그폴라 사상을 이용한 방법이 가장 빠르다.

• 대한가정학회지
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• 제46권4호
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• pp.25-35
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• 2008

The purpose of this study was to investigate the relationship pattern among the children's negative and aimless behaviors, and the variables related to teachers (characteristics, stress, efficacy, and quality of teachers' behaviors). Subjects were 190, 5 year-old children and 48 teachers at 45 child care centers. The children's negative and aimless behaviors were observed with time sampling method. The quality of teachers' interaction behaviors was rated by the Assessment Scales for Day Care Programs during the free play activities. Teachers responded to the Scale for the Teachers' Job Stress and Teachers' Efficacy. The data were analyzed with descriptive statistics, Pearson's correlations, multiple regressions, and partial correlations. The results were as follows. The teachers' experience and the quality of teachers' behaviors significantly explained the children's negative behaviors. The quality of teachers' behaviors significantly explained the children's aimless behaviors. Lastly, the quality of teachers' behaviors mediated the relationship between the teachers' job stress and the children's aimless behaviors.

• 천문학회보
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• 제36권1호
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• pp.82.1-82.1
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• 2011

We present a new code for solving non-LTE radiative transfer problems in a general grid (RIG). RIG develops from RATRAN code (Hogerheijde & van der Tak 2000) using the Accelerated Monte-Carlo method, and it can cope with line overlap effect among multiple molecular and atomic species. In this algorithm we make grids in arbitrary coordinates adequate to the problem, but, on the other hand, photons propagate in the Cartesian coordinates. For spherical, cylindrical and other well defined coordinate, the problem of tracing photon's path reduces to solving simple quadratic equations. For example, the outflow in the star formation have high dynamic range in scales from a few AU to ~ 0.1 pc and have also cylindrical symmetry. So, we have used (r, ${\alpha}$) coordinate system, where r is the distance from the origin and ${\alpha}$ is z/ R2 in the cylindrical coordinate of (R,z). The (r, ${\alpha}$) coordinate realizes the density - power function of r - and temperature distributions of the problems with smaller numbers of grid than the cylindrical coordinate does, and the former consumes less time to solve the problems than the latter.

• 디지털산업정보학회논문지
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• 제8권3호
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• pp.133-145
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• 2012

This paper describes the high density discrete wavelet transformation which is one that expands an N point signal to M transform coefficients with M > N. The double-density discrete wavelet transform is one of the high density discrete wavelet transformation. This transformation employs one scaling function and two distinct wavelets, which are designed to be offset from one another by one half. And it is nearly shift-invariant. Similarly, triple-density discrete wavelet transformation is a new set of dyadic wavelet transformation with two generators. The construction provides a higher sampling in both time and frequency. Specifically, the spectrum of the first wavelet is concentrated halfway between the spectrum of the second wavelet and the spectrum of its dilated version. In addition, the second wavelet is translated by half-integers rather than whole-integers in the frame construction. This arrangement leads to high density wavelet transformation. But this new transform is approximately shift-invariant and has intermediate scales. In two dimensions, this transform outperforms the standard and double-density discrete wavelet transformation in terms of multiple directions. Resultingly, the proposed wavelet transformation services good performance in image and video processing fields.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.2094-2112
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• 2019

Focusing on the issue that the conventional Kernel Correlation Filter (KCF) algorithm has poor performance in handling scale change and obscured objects, this paper proposes an anti-occlusion and scale adaptive tracking algorithm in the basis of KCF. The average Peak-to Correlation Energy and the peak value of correlation filtering response are used as the confidence indexes to determine whether the target is obscured. In the case of non-occlusion, we modify the searching scheme of the KCF. Instead of searching for a target with a fixed sample size, we search for the target area with multiple scales and then resize it into the sample size to compare with the learnt model. The scale factor with the maximum filter response is the best target scaling and is updated as the optimal scale for the following tracking. Once occlusion is detected, the model updating and scale updating are stopped. Experiments have been conducted on the OTB benchmark video sequences for compassion with other state-of-the-art tracking methods. The results demonstrate the proposed method can effectively improve the tracking success rate and the accuracy in the cases of scale change and occlusion, and meanwhile ensure a real-time performance.

• 응용통계연구
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• 제19권2호
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• pp.319-330
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• 2006

현실세계에서 관찰되는 시그널(signal)은 다양한 주파수(frequency)들의 시그널로 혼합되어 있는 경우가 많다. 예를 들어 태양 흑점 자료의 경우 약 11년 주기와 85년 주기로 변동한다는 사실은 널리 알려져 있다. 또한 경제 시계열 자료의 경우는 통상적으로 계절요인(seasonal component), 순환요인(cyclic component) 그리고 장기적인 추세요인(long-term trend)으로 분해하여 분석한다. 이러한 시계열 자료를 구성요소별로 분해하는 것은 오래된 주제중 하나이다. 전통적인 시계열자료 분석기법으로 스펙트럴 분석기법 등이 널리 사용되고 있으나 시계열 자료들이 비정상(nonstationary)일 경우에는 적용하기 어렵다. Huang et. al(1998)은 경험적 모드분해법(empirical mode decomposition)이라고 하는 자료적응적인(data-adaptive) 방법을 제안하였는데, 비정상성(nonstationarity)에 대한 강건성(robustness)으로 여러 분야에 널리 응용되고 있다. 그러나 Huang et. at(1998)은 잡음(error)에 의해 오염된 자료에 대한 구체적인 처리방법은 제시하지 못하고 있다. 본 논문을 통하여 효율적인 잡음제거 방법을 제안하고자 한다.