• 대한기계학회논문집
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• 제19권8호
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• pp.1982-1988
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• 1995

Methane/Air premixed flames are studied numerically, using a detailed chemical model, to investigate the flame strech effects on the extinction in a counterflow. The finite difference method, time integration and modified Newton iteration are used, and adaptive grid technique and grid smoothing have been employed to adjust the grid system according to the spatial steepness of the solution profiles. Results show that the flame stretch, or the conventional nondimensionalized stretch having the tangential flow characteristics of the stretched flame alone cannot adequately describes the extinction phenomena. On the other hand, the local flame stretch having both the normal and tangential flow characteristics of the stretched flame can give a proper explanation to the extinction of the symmetric planar premixed flames stabilized in a counter flow. The extinction condition were found to be a constant local stretch regardless of the equivalence ratio.

• Interaction and multiscale mechanics
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• 제2권3호
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• pp.277-293
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• 2009

The Enriched Free Mesh Method (EFMM) is a patch-wise procedure in which both a displacement field on an element and a stress/strain field on a cluster of elements connected to a node can be defined. On the other hand, the Superconvergent Patch Recovery (SPR) is known to be an efficient post-processing procedure of the finite element method to estimate the error norm at a node. In this paper, we discuss the relationship between solutions of the EFMM and those of the SPR through several convergence studies. In addition, in order to solve the demerit of the smoothing effect on the fracture mechanics fields, we implement a singular stress field to a local patch in the EFMM, and its effectiveness is investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1334-1339
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• 2003

An efficient method is developed for the shape optimization of 2-D structures. The sequential linear programming is used for minimization problems. Selected set of master nodes are employed as design variables and assigned to move towards the normal direction. After adapting the nodes on the design boundary, the B-spline curves and mesh smoothing schemes are used to maintain the finite element in good quality. Finally, a numerical implementation of optimum design of an automobile torque converter piston subjected to pressure and centrifugal loads is presented. The results shows additional weight up to 13% may be saved after the shape optimization.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 춘계학술발표대회
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• pp.589-592
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• 2005

웹을 통한 정보량의 폭발적인 증가로 인하여, 사용자에게 적합한 정보만을 제공할 수 있는 개인화 기술에 관심이 증가하고 있다. 정보를 선별하고 추천하는 대표적인 개인화 기술로서 Contentbased Filtering(CBF) 기법과 Collaborative Filtering(CF) 기법이 널리 사용되고 있다. 본 논문에서는 위에서 언급한 CBF 기법과 CF 기법을 혼합하여, 사용자 선호도를 보다 정확하게 반영할 수 있는 새로운 모델을 제시한다. 또한, Demographic Filtering 기법과 전문가의 추천을 고려한 Fusion Model 을 제시한다. 그리고 사용자 선호 모델을 실시간으로 반영하기 위한 업데이트 방법을 Exponential Smoothing 기법을 사용하여 구성하였다.

• 대한의용생체공학회:의공학회지
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• 제26권3호
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• pp.171-176
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• 2005

This paper proposes an automatic liver segmentation method using improved partial histogram threshold (PHT) algorithms. This method removes neighboring abdominal organs regardless of random pixel variation of contrast enhanced CT images. Adaptive multi-modal threshold is first performed to extract a region of interest (ROI). A left PHT (LPHT) algorithm is processed to remove the pancreas, spleen, and left kidney. Then a right PHT (RPHT) algorithm is performed for eliminating the right kidney from the ROI. Finally, binary morphological filtering is processed for removing of unnecessary objects and smoothing of the ROI boundary. Ten CT slices of six patients (60 slices) were selected to evaluate the proposed method. As evaluation measures, an average normalized area and area error rate were used. From the experimental results, the proposed automatic liver segmentation method has strong similarity performance as the MSM by medical Doctor.

• Spatial Information Research
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• 제3권1호
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• pp.19-27
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• 1995

논문에서 다룰 시스템은 영상 처리를 이용한 전처리과정에서 사용자에게 필요한 정보를 얻은 뒤 이 자료를 상호교류적으로 입력하는 반자동 지도입력시스템이다. 영상 처리는 주로 중요한 정보의 하나인 외곽선 추출에 주력하였고 이를 위해 적응성 평활화 필터와 연결보존외곽선추출를 사용하였다. 외곽선 정보는 편집기에서 벡터화 하며 편집의 효율을 높이기 위해 내부 자료구조는 확장된 사진트리 구조를 사용하였다. 이러한 작업들은 그 특성에 따라 개인용 컴퓨터와 워크스테이션에 각각 분담시켰고 네트웍을 통해 저장기기를 공유하여 작업의 일관성및 단순화를 추구하였다.

• 스마트미디어저널
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• 제4권3호
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• pp.44-49
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• 2015

Text line segmentation is a preprocessing step in OCR, which can significantly influence the accuracy of document analysis applications. This paper proposes a novel methodology for the text line segmentation of handwritten documents. First, the average width of the connected components is used to form a 1-D Gaussian kernel and a smoothing operation is then applied to the input binary image. The adaptive binarization of the smoothed image forms the final text lines. In this work, the segmentation method involves two stages: firstly, the large connected components are labelled as a unique text line using text line area mapping. Secondly, the final refinement of the segmentation is performed using the Euclidean distance between the text line and small connected components. The group of uniquely labelled text candidates achieves promising segmentation results. The proposed approach works well on Korean and English language handwritten documents captured using a camera.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.29-32
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• 1993

A technique computing short-term load foadcasting is essential for monitoring and controlling power system operation. This paper shows the use of general exponential smoothing to develop an adaptive forecasting system based on observed value of hourly demand. Forecasts of hourly load with lead times of one to twenty-four hours are computed at hourly intervals throughout the week. Standard error for lead times of one to twenty-four hour range from three to four percent average load. Studies are planned to investigate the use of weather influence to increase forecast accuracy.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 추계학술발표대회
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• pp.572-575
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• 2010

본 논문은 SNR 이 매우 낮은 저조도 영상의 잡음 제거를 위한 새로운 기술을 제안한다. 제안하는 기술은 입력 영상에서 파라미터를 자동/적응적 방식으로 추정하는 알고리즘을 특징으로 한다. 제안하는 기술의 효율성을 검증하기 위해 실질적인 환경에서 취득한 저조도 동영상들을 가지고 실험을 수행하였다. 실험을 통해 제안하는 기술을 활용하여 적응적으로 추정된 파라미터가 필터링(filtering) 성능을 잘 유지시킴을 검증하였다. 또한 기존 연구들과 비교할 때 저조도 동영상의 명암대비 향상과 잡음 제거에 우수한 결과를 보임을 검증하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.231-239
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• 2009

The filtered-x LMS (FX-LMS) algorithm has been applied to the active noise control (ANC) system in an acoustic duct. This algorithm is designed based on the FIR (finite impulse response) filter, but it has a slow convergence problem because of a large number of zero coefficients. In order to improve the convergence performance, the step size of the LMS algorithm was modified from fixed to variable. However, this algorithm is still not suitable for the ANC system of a short acoustic duct since the reference signal is affected by the backward acoustic wave propagated from a secondary source. Therefore, the recursive filteredu LMS algorithm (FU-LMS) based on infinite impulse response (IIR) is developed by considering the backward acoustic propagation. This algorithm, unfortunately, generally has a stability problem. The stability problem was improved by using an error smoothing filter. In this paper, the recursive LMS algorithm with variable step size and smoothing error filter is designed. This recursive LMS algorithm, called FU-VSSLMS algorithm, uses an IIR filter. With fast convergence and good stability, this algorithm is suitable for the ANC system in a short acoustic duct such as the intake system of an automotive. This algorithm is applied to the ANC system of a short acoustic duct. The disturbance signals used as primary noise source are a sinusoidal signal embedded in white noise and the chirp signal of which the instantaneous frequency is variable. Test results demonstrate that the FU-VSSLMS algorithm has superior convergence performance to the FX-LMS algorithm and FX-LMS algorithm. It is successfully applied to the ANC system in a short duct.