• 지구물리와물리탐사
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• 제17권2호
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• pp.88-94
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• 2014

탄성파 탐사자료의 획득 시, 기계적인 결함이나 지형적인 접근성 등으로 인하여 자료를 부분적으로 획득하지 못하거나, 해상 탐사의 경우 스트리머의 간격으로 인하여 공간적인 알리아싱(aliasing)이 발생할 수 있다. 이러한 불규칙하고 공간적인 알리아싱이 존재하는 자료는 추후 탄성파 자료처리과정에서 문제를 일으키게 된다. 만약, 정확하고 효율적인 내삽(interpolation) 기법을 보유하고 있다면, 이러한 문제를 해결할 수 있으며, 나아가 탐사를 수행할 때 송신원 또는 수신기의 수를 줄일 수 있으므로 탐사의 시간 및 비용이 줄어들게 된다. 여러 내삽 방법들 중 Matching Pursuit 기법을 이용한 내삽 방법은 고르기(sampling)의 형태와 상관없이 적용이 가능하다는 장점을 가지고 있다. 그러나 정현파 함수(sinusoidal function)을 기저함수로 이용하는 경우, 공간적인 알리아싱이 존재하는 탄성파자료에 적용시 정확한 내삽이 불가능하다는 한계를 지니고 있다. 따라서 본 연구에서는 공간적인 알리아싱의 문제를 해결하기 위하여, 정현파 함수가 아닌 요소파(wavelet)를 기저함수로 이용하는 요소파 기반의 Matching Pursuit 기법을 개발하였다. 또한, L-2 norm을 이용한 기존의 방법과 달리, 내적을 이용하여 내삽의 수행속도를 향상시켰다.

• 한국멀티미디어학회논문지
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• 제6권5호
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• pp.937-944
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• 2003

다중 에이전트 시스템에서 가장 중요한 문제는 여러 에이전트가 서로 효율적인 협동(coordination)을 통해서 목표(goal)를 성취하는 것과 다른 에이전트들과의 충돌(collision) 을 방지하는 것이다. 본 논문에서는 먹이 추적 문제의 목표를 효율적으로 성취하기 위해 새로운 전략 방법을 제안한다. 제안된 제어 전략은 다중 에이전트를 제어하기 위해 강화 학습을 이용하였고, 에이전트들 간의 거리관계와 공간 관계를 고려하였다.

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1343-1358
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• 2020

In the stagewise arithmetic orthogonal matching pursuit algorithm, the weak threshold used in sparsity estimation is determined via maximum iterations. Different maximum iterations correspond to different thresholds and affect the performance of the algorithm. To solve this problem, we propose an improved variable weak threshold based on the stagewise arithmetic orthogonal matching pursuit algorithm. Our proposed algorithm uses the residual error value to control the weak threshold. When the residual value decreases, the threshold value continuously increases, so that the atoms contained in the atomic set are closer to the real sparsity value, making it possible to improve the reconstruction accuracy. In addition, we improved the generalized Jaccard coefficient in order to replace the inner product method that is used in the stagewise arithmetic orthogonal matching pursuit algorithm. Our proposed algorithm uses the covariance to replace the joint expectation for two variables based on the generalized Jaccard coefficient. The improved generalized Jaccard coefficient can be used to generate a more accurate calculation of the correlation between the measurement matrixes. In addition, the residual is more accurate, which can reduce the possibility of selecting the wrong atoms. We demonstrate using simulations that the proposed algorithm produces a better reconstruction result in the reconstruction of a one-dimensional signal and two-dimensional image signal.

• 전자공학회논문지CI
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• 제48권2호
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• pp.78-85
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• 2011

본 논문에서는 운전자의 특성, 도로상황, 경로 추천을 담당하는 에이전트와 같은 동적환경정보(DEI:Dynamic Environment Information)를 반영하여 실시간으로 운전자에게 경로를 추천할 수 있는 시스템을 위해 멀티에이전트에 관한 연구를 수행하였다. DEI는 n개의 멀티 에이전트이며 운전자에게 최적화된 경로를 제공할 수 있는 경로추천시스템에 활용되는 환경변수이다. DEI가 반영되는 경로추천 시스템은 멀티 에이전트 연구의 새로운 연구 분야라 할 수 있겠다. 이를 위하여 멀티에이전트 연구의 대표적 실험 환경인 먹이추적문제를 이용하여 새로운 해법을 찾고자 하였다. 본 논문에서는 기존의 먹이추적 실험은 현실성이 결여된 멀티에이전트 연구였기에 기존의 실험환경과 달리 현실세계와 비슷한 실험환경을 제안을 하며 새로운 전략인 Ant-Q 학습을 적용한 알고리즘과 기존의 방향벡터를 활용한 전략과의 비교를 통해 새로운 환경에서의 성능의 향상을 입증할 수 있었다.

• 한국정보통신학회논문지
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• 제17권10호
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• pp.2252-2258
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• 2013

본 논문에서는 복수측정벡터 환경에서 성긴 신호의 복원을 위하여 널리 사용되고 있는 Simultaneous orthogonal matching pursuit (S-OMP) 기술을 보완한 병렬 OMP 기법을 제안하고 그 성능을 분석한다. Parallel orthogonal matching pursuit(POMP) 알고리즘은 간단하지만 성능면에서 매우 효과적이다. 제안된 병렬 OMP알고리즘은 첫 번째 반복 과정에서 관찰 행렬과 상관도가 높은 인덱스 집합을 여러 개 (M) 선택한다. 그 후, 선택된 각각의 인덱스를 첫 번째 인덱스로 하는 각 병렬 OMP블록에서 S-OMP 알고리즘 기법이 병렬적으로 동작한다. 마지막으로 입력된 신호 복원을 위해 잔차가 가장 작은 POMP블록의 인덱스 집합을 선택한다. 컴퓨터 시뮬레이션을 통해 100%복원 가능한 sparsity 개수가 기존의 S-OMP 기법에 비해 M이 증가함에 따라 향상되는 것을 확인했으며, 평균 제곱 오차 측면에서도 SNR에 상관없이 성능 개선효과가 있음을 확인하였다.

• ETRI Journal
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• 제42권3호
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• pp.376-387
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• 2020

Massive computation of the reconstruction algorithm for compressive sensing (CS) has been a major concern for its real-time application. In this paper, we propose a novel high-speed architecture for the orthogonal matching pursuit (OMP) algorithm, which is the most frequently used to reconstruct compressively sensed signals. The proposed design offers a very high throughput and includes an innovative pipeline architecture and scheduling algorithm. Least-squares problem solving, which requires a huge amount of computations in the OMP, is implemented by using systolic arrays with four new processing elements. In addition, a distributed-arithmetic-based circuit for matrix multiplication is proposed to counterbalance the area overhead caused by the multi-stage pipelining. The results of logic synthesis show that the proposed design reconstructs signals nearly 19 times faster while occupying an only 1.06 times larger area than the existing designs for N = 256, M = 64, and m = 16, where N is the number of the original samples, M is the length of the measurement vector, and m is the sparsity level of the signal.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2400-2413
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• 2019

Doubly-selective (DS) fading channel is often occurred in many orthogonal frequency division multiplexing (OFDM) communication systems, such as high-speed rail communication systems and underwater acoustic (UWA) wireless networks. It is challenging to provide an accurate and fast estimation over the doubly-selective channel, due to the strong Doppler shift. This paper addresses the doubly selective channel estimation problem based on complex exponential basis expansion model (CE-BEM) in OFDM systems from the perspective of distributed compressive sensing (DCS). We propose a novel DCS-based improved sparsity adaptive matching pursuit (DCS-IMSAMP) algorithm. The advantage of the proposed algorithm is that it can exploit the joint channel sparsity information using dynamic threshold, variable step size and tailoring mechanism. Simulation results show that the proposed algorithm achieves 5dB performance gain with faster operation speed, in comparison with traditional DCS-based sparsity adaptive matching pursuit (DCS-SAMP) algorithm.

• 대한가정학회지
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• 제45권7호
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• pp.93-103
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• 2007

The purpose of the study was to examine the relationships between children's emotional regulation, perceived self-competence and behavior problem. The subjects were 357 elementary school students in Busan. The questionnaires on children's emotional regulation, perceived self-competence and behavior problem were used. The results were as follows: (1) According to sex, there were significant differences in children's emotional regulation scores(venting and support pursuit), and according to birth order, there were significant differences in children's perceived self-competence scores and behavior problem scores. (2) There were significant correlations between children's emotional regulation scores and behavior problem scores, and also there were significant correlations between children's perceived self-competence scores and behavior problem scores. (3) Children's perceived self-competence and emotional regulation explained children's anxiety behavior, withdrawal behavior, aggressive behavior, distracted behavior and regressive behavior.

• 간호행정학회지
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• 제11권4호
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• pp.439-448
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• 2005

Purpose: Purpose of the this study is to define the hemodialysis treatment-related stressors and stress coping methods in hemodialysis noncompliant patients. Method: Hemodialysis treatment-related stressors scale and stress coping style scale were used with 178 patients that received continuous hemodialysis treatment, met the noncompliance criteria. Collected data were analyzed by using the SPSS 12.0 program. Result: In hemodialysis noncompliant patients, Psychosocial stress were higher than physical stress, 'aesthetic thinking' was the most used. As recognition of health status was lower, hemodialysis treatment-related stressors were higher. In terms of causative disease, 'hypertension' pt used more 'problem-focus coping' and 'social support pursuit' than the other groups. As subjective recognition level of health status was higher, 'problem-focus coping' and 'social support pursuit' were more used. It was showed positive correlation between psychosocial stressors and 'aesthetic thinking'. Conclusion: Hemodialysis noncompliant patients had high psychosocial stress, accordingly, used 'aesthetic coping'. It means that they has negative coping to disease and hemodialysis treatment. Therefore, Nurses need to manage psychosocial aspects, which influence on noncompliant behaviors.

• 한국식생활문화학회지
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• 제33권1호
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• pp.11-17
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• 2018

This study examined the relationship between coping style for stress and emotional eating behavior focused on gender difference. A total of 475 college students(males, 244; females, 231) participated in this study. The results were as follows. First, there were significant gender difference in coping style for stress. The scores of male students were significantly higher than those of female students in the problem-focused and self-comforting coping styles, whereas scores of female students were significantly higher than male students in social support pursuit and emotion-focused coping styles. Second, there were significant gender difference in emotional eating behavior. Female students reported higher emotional eating behavior than male students. Third, male students preferred a problem-focused coping style, whereas female students preferred a social support pursuit coping style the most. Fourth, the interaction of gender and coping style for stress were not related to the emotional eating behavior. Both of male and female students who preferred an emotion focused coping style reported the highest score in emotional eating behavior. The limitations of the present study and suggestions for future research were discussed.