• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1018-1021
• /
• 2007

This paper explores the use of BEM based NAH to reconstruct the surface vibration of a plate in a rectangular finite cavity, in which the distances between sensors and the nearest points on the source surface are not equal. In such circumstances, different degree of information on propagating and non-propagating wave components will be detected by sensors at different positions, as well as the influence of measurement noise will vary significantly from the nearest points of measurement to the farthest ones. On the other hand, the condition number of the vibro-acoustic transfer function matrix relating normal surface velocities and field pressures will becomes high, numerically indicating an increase of linear dependency between rows of transfer function matrix. The combination of poor measurement and high condition number will result inaccurate reconstruction. Therefore, one approach to be investigated in this work is to select the measurement positions in such ways that reduce measurement redundancy, as it indicated by the condition number. The improvement is found to be significant in the numerical simulations utilizing two different criterions, spanning from over-determined to under-determined cases, and in the validation experiment.

• 한국전자통신학회논문지
• /
• 제14권6호
• /
• pp.1187-1196
• /
• 2019

정보 보안은 클라우드 및 소셜 네트워킹 사이트의 출현으로 주요 과제가 되었다. 기존의 암호화 알고리즘은 디지털 영상의 큰 데이터 크기와 원시 픽셀 간에 높은 중복성으로 인해 영상 암호화에 적합하지 않을 수 있다. 본 논문에서는 Jeong 등이 제안한 컬러 영상의 암호화 방법을 C-MLCA와 Laplace 전개를 이용한 매개변수식 3차원 카오스 캣맵을 사용하여 일반화한다. 제안된 새로운 영상 암호시스템이 높은 보안성과 신뢰성을 제공한다는 것을 엄격한 실험을 통해 입증한다.

• 한국콘텐츠학회논문지
• /
• 제11권4호
• /
• pp.51-56
• /
• 2011

본 논문은 명암 변화가 심한 비디오 시퀀스에 대해 효율적인 동영상 압축기법을 제안한다. 제안한 알고리즘에서는 화면간의 명암 변화 변수들을 추정하고 지역적인 움직임 보상을 수행한다. 밝기 보상이 필요한 화면을 검출하기 위하여 연속되는 두 프레임간의 히스토그램의 크로스 엔트로피를 계산하여 프레임 분류를 하고 명암 변화가 심한 화면에 대해서만 밝기 보상을 수행하여 명암 변화가 심하지 않은 경우에 발생할 수 있는 불필요한 계산량을 줄였다. 명암 변화가 심한 비디오 시퀀스에 대한 실험결과 제안한 알고리즘은 기존의 알고리즘에 비해 적은 계산량으로 높은 PSNR (peak signal to noise ratio) 성능을 나타내었다.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 2003년도 추계학술대회 및 정기총회
• /
• pp.89-92
• /
• 2003

It is often that a large-scale linear programming(LP) problem may contain many constraints which are redundant or cause infeasibility on account of inefficient formulation or some errors in data input. Presolving or preprocessing is a series of operations which removes the underlying redundancy or detects infeasibility in the given LP problem. It is essential for the speedup of an LP system solving large-scale problems to implement presolving techniques. For the recovery of an optimal solution for the original problem from an optimal solution for the presolved problem, a special procedure, so called postsolving, must be applied. In this paper, we present how a postsolving procedure is constructed and implemented in LPABO, a interior-point based LP system. Briefly, all presolving processes are logged in a data structure in LPABO, and after the end of the solution method an optimal solution for the original problem is obtained by tracing the logs. In each stage of the postsolving procedure, the optimality of intermediate solutions is maintained. We tested our postsolving procedure on Netlib, Gondzio and Kennington LP data sets, and concluded that the computational burden of the procedure is relatively negligible compared with the total solving time.

• Journal of Mechanical Science and Technology
• /
• 제14권6호
• /
• pp.605-621
• /
• 2000

A mobile manipulator-a serial connection of a mobile platform and a task robot-is redundant by itself. Using its redundant freedom, a mobile manipulator can move in various modes, i. e., can perform dexterous tasks. In this paper, to improve task execution efficiency utilizing redundancy, optimal configurations of the mobile manipulator are maintained while it is moving to a new task point. Assuming that a task robot can perform the new task by itself, a desired configuration for the task robot can be pre-determined. Therefore, a cost function for optimality can be defined as a combination of the square errors of the desired and actual configurations of the mobile platform and of the task robot. In the combination of the two square errors, a newly defined mobility of a mobile platform is utilized as a weighting index. With the aid of the gradient method, the cost function is minimized, so the tasle that the mobile manipulator performs is optimized. The proposed algorithm is experimentally verified and discussed with a mobile manipulator, PURL-II.

• 한국음향학회지
• /
• 제15권6호
• /
• pp.99-103
• /
• 1996

파형부호화법은 파형의 잉여성분 제거과정을 통해 음성파형의 꼴을 단순히 보존하는 부호화법이다. 음성합성분야에서 파형부호화법은 주로 분석에 의한 고음질 합성방식으로 적용되고 있다. 그렇지만 이 부호화법은 분석시에 여기원과 성도여파기 피라미터들로 분류하여 처리하지 않기 때문에 규칙에 의한 합성방식으로는 적용하기가 힘들다. 본 논문에서는 스펙트럼영역에서 유성스펙트럼에 대해서만 스펙트럼축의 변경을 통해 피치를 조절하는 새로운 피치변경법을 제안하였다. 이 방법은 주파수영역의 처리법이며 50%의 피치변경을 수행하여도 스펙트럼 왜곡율이 2.7% 이하로 얻어졌고, 시간영역의 위상특성 보상에 의해 프레임간의 진폭연결이 자연스럽다는 장점을 갖느다.

• 한국멀티미디어학회논문지
• /
• 제20권6호
• /
• pp.853-864
• /
• 2017

HD padding area is essential redundancy in HD broadcasting. It is possible to use this padding area for the purpose of improving DTV broadcasting services. For utilization of this area, The bit of a service data was converted to black and white $8{\times}8$ block image. Converted block images are compressed with active video and are delivered to a receiver as only DC coefficients in a video stream. video quality is not effected by the proposed method, and service data was perfectly recovered in receiver without errors by using block average and threshold. The proposed utilization of HD essential padding area can possibly overcome the limited transmission stream rate with the bandwidth of HD broadcasting. If service data in transport or video stram were transferred using this padding area, it is possible to improve video quality with expanded video stream rate. Additionally, because the proposed methods are based on well-established standards, it is also useful for world-wide HD broadcasting systems such as ATSC, DVB, and IPTV.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
• /
• pp.576-578
• /
• 1999

본 논문에서는 생물학적인 DNA와 유전자 알고리즘의 진화 메커니즘에 근거를 둔 DNA 코딩방법을 변형하여 새로운 DNA 코딩 방법을 제안한다. 이 방법은 기존의 DNA 코딩 방법이 DNA 유전자의 Redundancy와 Over-lapping 성질 때문에 갖고 있는 DNA 자체의 특성인 염색체의 길이를 자유자재로 변화시킬 수 있는 코딩 기술에 진화단계에서 변형을 가할 수 있는 새로운 유전자 알고리즘을 추가하여, 초기에 국소해로 접근하는 일반적인 유전자 알고리즘의 위험 부담률을 줄이고, 전역 해로의 접근 가능성을 높이는 방법을 제시한다. 또한. 이 변형된 DNA 코딩 방법의 가능성을 입증하기 위하여 시스템 제어에 필요한 지식을 표현하는 적당한 퍼지 규칙을 후건부의 매개변수의 동조만을 통하여 획득하고, 이 규칙에 변형된 DNA 코딩 방법을 적용하여 최적화 된 새로운 퍼지규칙 획득 알고리즘을 개발한다. 제안된 알고리즘을 이용한 퍼지 제어기를 설계하고. 이 제어기의 유용성을 입증하기 위하여 병렬형 이중 도립진자 시스템에 적용하여 시뮬레이션을 실행한 결과 효과적으로 퍼지규칙을 획득하고 제어함을 알 수 있다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
• /
• pp.125-127
• /
• 2004

High-resolution satellite images offer abundance information of the earth surface for remote sensing applications. The information includes geometry, texture and attribute characteristic. The pixel-based image classification can't satisfy high-resolution satellite image's classification precision and produce large data redundancy. Object-oriented information extraction not only depends on spectrum character, but also use geometry and structure information. It can provide an accessible and truly revolutionary approach. Using Beijing Spot 5 high-resolution image and object-oriented classification with the eCognition software, we accomplish the cultures' precise classification. The test areas have five culture types including water, vegetation, road, building and bare lands. We use nearest neighbor classification and appraise the overall classification accuracy. The average of five species reaches 0.90. All of maximum is 1. The standard deviation is less than 0.11. The overall accuracy can reach $95.47\%.$ This method offers a new technology for high-resolution satellite images' available applications in remote sensing culture classification.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.2485-2489
• /
• 2005

This paper introduces a new preprocessing scheme to replace original data of gray scale images with particular ordered data so that performance of lossless compression can be improved more efficiently. As a kind of preprocessing technique to maximize performance of entropy encoder, the proposed method converts the input image data into more compressible form. Before encoding a stream of the input image, the proposed preprocessor counts co-occurrence frequencies for neighboring pixel pairs. Then, it replaces each pair of adjacent gray values with particular ordered numbers based on the investigated co-occurrence frequencies. When compressing ordered image using entropy encoder, we can expect to raise compression rate more highly because of enhanced statistical feature of the input image. In this paper, we show that lossless compression rate increased by up to 37.85% when comparing results from compressing preprocessed and non-preprocessed image data using entropy encoder such as Huffman, Arithmetic encoder.