• Journal of Information Processing Systems
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• 제15권5호
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• pp.1218-1230
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• 2019

This study proposes a novel video traffic flow detection method based on machine vision technology. The three-frame difference method, which is one kind of a motion evaluation method, is used to establish initial background image, and then a statistical scoring strategy is chosen to update background image in real time. Finally, the background difference method is used for detecting the moving objects. Meanwhile, a simple but effective shadow elimination method is introduced to improve the accuracy of the detection for moving objects. Furthermore, the study also proposes a vehicle matching and tracking strategy by combining characteristics, such as vehicle's location information, color information and fractal dimension information. Experimental results show that this detection method could quickly and effectively detect various traffic flow parameters, laying a solid foundation for enhancing the degree of automation for traffic management.

• 한국통신학회논문지
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• 제41권10호
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• pp.1179-1182
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• 2016

본 논문에서는 sine-linear phase difference 방식과 DPCM 방식의 차동 양자화 기술을 응용하여 새로운 ROM 압축방식을 제안하고 이를 이용하여 저전력 직접 디지털 주파수 합성기를 FPGA를 사용하여 설계 및 제작한다. ROM 크기를 줄이기 위해 사인파의 1/4 주기를 $2^N$간격으로 표본화하여 양자화된 값을 양자화 ROM1에 저장하고 각 표본화 사이를 $2^K$간격으로 표본화하고 ROM1에 저장된 표본화 값의 차이를 ROM2에 저장하여 ROM의 크기를 줄이는 방식을 사용한다. 이를 사용함으로써 기존 방식 대비 약 37%의 ROM 크기만 필요하게 되여 전력 소모를 줄일 수 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.181-182
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• 2003

A preconditioned numerical method for gas-liquid to-phase flow is applied to solve cavitating flow. The present method employs a density based finite-difference method of dual time-stepping integration procedure and Roe's flux difference splitting approximation with MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The method permits simple treatment of the whole gas-liquid two-phase flow field including wave propagation, large density changes and incompressible flow characteristics at low Mach number. By this method, two-dimensional internal flows through a venturi tuve and decelerating cascades are computed and discussed.

• 한국전산구조공학회논문집
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• 제27권1호
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• pp.17-26
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• 2014

본 논문은 MLS(Moving Least Squares) 차분법을 바탕으로 동적균열전파 해석을 수행하기 위한 알고리즘을 제시한다. MLS 차분법은 절점만으로 이루어진 수치모델을 사용하며, 이동최소제곱법을 이용하여 전개한 Taylor 다항식을 기초로 미분근사식을 유도하기 때문에, 요소망의 제약에서 완벽하게 벗어난 절점해석이 가능하다. 시간항을 포함하는 동적 평형방정식은 Newmark 방법으로 시간적분 하였다. 동적하중을 받는 균열이 전파할 때, 매 시간단계마다 절점모델을 재구성하지 않고 균열선단 주변에서 국부적인 수정을 통해 해석이 가능하다. 동적균열을 묘사하기 위해 가시한계법(visibility criterion)을 적용하였고, 동적 에너지해방률을 산정하여 균열의 진전유무와 그에 상응하는 진전방향을 결정하였다. 모드 I 상태와 혼합모드 상태에서 균열이 진전하는 현상을 모사하였고, 이론해와 Element-Free Galerkin법으로 계산한 결과와의 비교를 통해 개발된 알고리즘의 정확성과 안정성을 검증하였다.

• 한국전산구조공학회논문집
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• 제24권5호
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• pp.577-588
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• 2011

본 논문은 복합 불연속면을 갖는 포텐셜 문제의 해석을 위해 확장된 MLS(Moving Least Squares) 차분법을 제시한다. 계면경계를 따라 해(solution)와 수직방향, 접선방향 미분들이 모두 불연속 특이성을 나타내는 복합 불연속면을 묘사하기 위해 계단함수, 쐐기함수, 가위함수와 같은 불연속 특이함수를 추가하여 기존의 MLS 차분법을 개선했다. 계면경계조건은 기지의 조건으로서 지배방정식의 이산화과정에서 추가의 미지계수를 발생시키지 않는다. 포아송 방정식 형태의 지배미분 방정식을 풀기 위해 내부영역과 경계에 절점을 배치하고 차분식을 구성한다. 차분식을 조립한 계 방정식을 직접 풀기 때문에 계산효율성이 매우 우수하다. 수치예제는 제시된 해석기법의 우수성을 잘 보여주며, 균열전파, 이동경계, 상호작용 문제 등 다양한 불연속 문제로의 확장이 기대된다.

• 대한전자공학회논문지
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• 제13권3호
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• pp.1-6
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• 1976

이 논문에서는 Boolean difference를 이용하여 combinational 및 sequential 논리회로에서 발생하는 기능적인 고장에 대한 test pattern을 얻는 방법을 연구하였다. 이 방법은 test pattern을 얻고자 하는 회로의 Boolean 함수의 Boolean difference를 계산하므로써 체계적으로 test pattern을 얻는 절차를 보여주고 있다. 컴퓨터에 의한 실험결과에 의하며 이 방법은 combinational 회로 및 asynchronous sequential 회로에 적합하며, clock이 있는 flip flop을 적당히 모형화함으로서 이 방법을 synchronous sequential회로에도 적용할 수 있음이 입증되었다. In this paper, a method of test pattern generation for the functional failure in both combinational and sequentlal logic networks by using exterded Boole an difference is proposed. The proposed technique provides a systematic approach for the test pattern generation procedure by computing Boolean difference of the Boolean function that represents the Logic network for which the test patterns are to be generated. The computer experimental results show that the proposed method is suitable for both combinational and asynchronous sequential logic networks. Suitable models of clocked flip flops may make it possible for one to extend this method to synchronous sequential logic networks.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제48권3호
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• pp.167-173
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• 2022

Objectives: The purpose of this study was to estimate the minimal clinically important difference (MCID) of mouth opening (MO) and patient satisfaction in surgically treated oral submucous fibrosis (OSMF) patients. Materials and Methods: The status of MO was collected preoperatively (T0), postoperatively at 3 months (T1), and at a minimum of 6 months postoperatively (T2). MCID was determined through the anchor-based approach with the change difference method, mean change method, and receiver operator characteristic curve (ROC) method. Results: In this study, 35 patients enrolled and completed postoperative follow-up (T2) averaging a duration of 18.1 months. At T1, using the change difference method, MO was 14.89 mm and the ROC curve exhibited a 11.5 gain in MO (sensitivity 81.8% and specificity 100%, area under the curve [AUC] of 0.902) and was classified as MCID as reported by patients. At T2, MCID of MO was 9.75 mm using the change difference method and 11.75 mm by the mean change method. The ROC curve revealed that the MCID of MO at T2 was 10.5 mm with 73.9% sensitivity and 83.3% specificity (AUC of 0.873). The kappa value was 0.91, confirming reliability of the data. Conclusion: This study demonstrated MCID values that indicate the clinical relevance of surgical treatment of OSMF if the minimum possible gain in MO is approximately 10 mm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권10호
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• pp.2514-2526
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• 2013

This paper presents a detection method for least significant bit matching revisited (LSBMR) steganography. Previous research shows that the adjacent pixels of natural images are highly correlated and the value 0 appears most frequently in pixel difference. Considering that the message embedding process of LSBMR steganography has a weighted-smoothing effect on the distribution of pixel difference, the frequency of the occurrence of value 0 in pixel difference changes most significantly whereas other values approximately remain unchanged during message embedding. By analyzing the effect of LSBMR steganography on pixel difference distribution, an equation is deduced to estimate the frequency of difference value 0 using the frequencies of difference values 1 and 2. The sum of the ratio of the estimated value to the actual value as well as the ratio of the frequency of difference value 1 to difference value 0 is used as the steganalytic detector. Experimental results show that the proposed method can effectively detect LSBMR steganography and can outperform previous proposed methods.

• Journal of applied mathematics & informatics
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• 제31권5_6호
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• pp.733-745
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• 2013

In this paper, we first propose a new technique of the functional iterative methods VIM (Variational iteration method) and NHPM (New homotopy perturbation method) for solving two-point boundary value problems, and then we compare their numerical results with those of the finite difference method (FDM).

• 한국멀티미디어학회논문지
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• 제13권6호
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• pp.833-840
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• 2010

In this paper a method for detecting and extracting the face from the image in YCbCr spaceis proposed. The face region is obtained from the complex original image by using the difference method and the face color information is taken from the reduced face region throughthe Ellipse clustering method. The experimental results showed that the proposed method can efficiently detect and extract the face from the original image under the general light intensity except for low luminance.