• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
• /
• pp.865-868
• /
• 1993

This paper describes a simple random signal generator employing by CMOS analog technology in current mode. The system is a nonlinear dynamical system described by a difference equation, such as x(t＋1) = f(x(t)) , t = 0,1,2, ... , where f($.$) is a nonlinear function of x(f). The tent map is used as a nonlinear function to produce the random signals with the uniform distribution. The prototype is implemented by using transistor array devices fabricated in a mass product line. It can be easily realized on a chip. Uniform randomness of the signal is examined by the serial correlation test and the $\chi$2 test.

• BMB Reports
• /
• 제35권5호
• /
• pp.465-471
• /
• 2002

From fruiting bodies of L. edodes strain L-54, single-spore isolates (SSIs) were collected. Two parental types of L-54 were regenerated via monokaryotization. By means of random-amplified polymorphic DNA (RAPD), DNA samples from L-54, its two parental types, and 32 SSIs were amplified with arbitrary primers. Dedikaryotization was demonstrated, and 91 RAPD-based molecular markers were generated. RAPD markers that were segregated at a 1:1 ratio were used to construct a linkage map of L. edodes. This RAPD-linkage map greatly enhanced the mapping of other inheritable and stable markers [such as those that are linked to a phenotype (the mating type), a known gene (priA) and a sequenced DNA fragment (MAT)] with the aid of mating tests, bulked-segregant analysis, and PCR-single-strand conformational polymorphism. These markers comprised a genetic map of L. edodes with 14 linkage groups and a total length of 622.4 cM.

• 대한수학회지
• /
• 제39권1호
• /
• pp.51-60
• /
• 2002

Some random fixed point theorems for nonexpansive and *-nonexpansive random operators defined on convex and star-shaped sets in a Frechet space are proved. Our work extends recent results of Beg and Shahzad and Tan and Yaun to noncontinuous multivalued random operators, sets analogue to an earlier result of Itoh and provides a random version of a deterministic fixed point theorem due to Singh and Chen.

• 전자공학회논문지
• /
• 제51권1호
• /
• pp.145-151
• /
• 2014

본 논문에서는 한 장의 영상에서 안개를 제거하는 알고리즘을 제안한다. 기존의 Dark Channel Prior(DCP) 알고리즘은 영상의 어두운 정보를 계산하여 전달량을 추정한 후, 매팅(matting) 기법을 사용하여 안개 영역을 보완하여 검출한다. 이 과정에서 블록현상이 발생하는 문제가 있으며 이로 인해 안개를 효율적으로 제거하는데 한계점이 있다. 이 문제를 해결하기 위해 본 논문에서는 Hidden Markov Random Field(HMRF) 와 Expectation-Maximization(EM) 알고리즘을 이용하여 매팅 과정에서 발생하는 블록문제를 해결하고자 하였다. 실험 결과를 통하여 제안한 방법은 기존 방법보다 안개제거에서 더 향상된 결과를 얻을 수 있음을 확인하였다.

• 대한수학회보
• /
• 제41권2호
• /
• pp.327-335
• /
• 2004

In this paper, we reformulate a snapshot attractor([5]), ($K,\;\={\mu_{\iota}}$) generated by a random baker's map with a sequence of probability measures {\={\mu_{\iota}}} on K. We obtain bounds of the correlation dimensions of ($K,\;\={\mu_{\iota}}$) for all ${\iota}\;{\geq}\;1$.

• 한국산학기술학회논문지
• /
• 제10권12호
• /
• pp.3688-3693
• /
• 2009

본 논문에서는 두 가지 혼돈맵들 -톱니맵 $S_2(x)$ 와 텐트맵 $T_2(x)-$ 을 연결시킨 하나의 합성맵을 기초로 사용하는 독립된 하나의 합성상태머신을 설계하는 방법 및 그 결과을 제시하였다. 두 가지 다른 혼돈맵들 -톱니맵과 텐트맵- 의 합성 논리를 이용하여 설계된 독립된 하나의 합성상태머신에서 발생하는 혼돈적인 상태들을 그래프적으로 보였으며, 발생하는 의사 난수적인 상태들의 주기는 이산화된 진리표의 정밀도에 따른 길이를 갖는다는 것도 보였다.

• 로봇학회논문지
• /
• 제7권2호
• /
• pp.150-159
• /
• 2012

In this paper, we propose a cost-aware Rapidly-exploring Random Tree (RRT) path planning algorithm for mobile robots. A mobile robot is presented with a cost map of the field of interest and assigned to move from one location to another. As a robot moves, the robot is penalized by the cost at its current location according to the cost map. The overall cost of the robot is determined by the trajectory of the robot. The goal of the proposed cost-aware RRT algorithm is to find a trajectory with the minimal cost. The cost map of the field can represent environmental parameters, such as temperature, humidity, chemical concentration, wireless signal strength, and stealthiness. For example, if the cost map represents packet drop rates at different locations, the minimum cost path between two locations is the path with the best possible communication, which is desirable when a robot operates under the environment with weak wireless signals. The proposed cost-aware RRT algorithm extends the basic RRT algorithm by considering the cost map when extending a motion segment. We show that the proposed algorithm gives an outstanding performance compared to the basic RRT method. We also demonstrate that the use of rejection sampling can give better results through extensive simulation.

• 제어로봇시스템학회논문지
• /
• 제12권5호
• /
• pp.450-456
• /
• 2006

Monte Carlo localization is known to be one of the most reliable methods for pose estimation of a mobile robot. Although MCL is capable of estimating the robot pose even for a completely unknown initial pose in the known environment, it takes considerable time to give an initial pose estimate because the number of random samples is usually very large especially for a large-scale environment. For practical implementation of MCL, therefore, a reduction in sample size is desirable. This paper presents a novel approach to reducing the number of samples used in the particle filter for efficient implementation of MCL. To this end, the topological information generated through the thinning technique, which is commonly used in image processing, is employed. The global topological map is first created from the given grid map for the environment. The robot then scans the local environment using a laser rangefinder and generates a local topological map. The robot then navigates only on this local topological edge, which is likely to be similar to the one obtained off-line from the given grid map. Random samples are drawn near the topological edge instead of being taken with uniform distribution all over the environment, since the robot traverses along the edge. Experimental results using the proposed method show that the number of samples can be reduced considerably, and the time required for robot pose estimation can also be substantially decreased without adverse effects on the performance of MCL.

• 로봇학회논문지
• /
• 제18권4호
• /
• pp.487-495
• /
• 2023

This paper presents a method for autonomous exploration of indoor environments using a 2-dimensional Light Detection And Ranging (LiDAR) scanner. The proposed frontier-based exploration method considers navigability from the current robot position to extracted frontier targets. An approach to constructing the point cloud grid map that accurately reflects the occupancy probability of glass obstacles is proposed, enabling identification of safe frontier grids on the safety grid map calculated from the point cloud grid map. Navigability, indicating whether the robot can successfully navigate to each frontier target, is calculated by applying the skeletonization-informed rapidly exploring random tree algorithm to the safety grid map. While conventional exploration approaches have focused on frontier detection and target position/direction decision, the proposed method discusses a safe navigation approach for the overall exploration process until the completion of mapping. Real-world experiments have been conducted to verify that the proposed method leads the robot to avoid glass obstacles and safely navigate the entire environment, constructing the point cloud map and calculating the navigability with low computing time deviation.

• 한국통신학회논문지
• /
• 제36권12C호
• /
• pp.738-743
• /
• 2011

고해상도 3차원 깊이 영상은 고품질의 3차원 방송을 위해 필요한 중요한 정보이다. 깊이 카메라는 정확한 깊이 정보를 실시간으로 얻을 수 있지만, 카메라 물리적 한계로 인해 저해상도의 깊이 영상만 이용한다. 본 논문에서는 저해상도의 깊이 영상과 색상 영상을 이용하여 색상 영상을 보간 하는 방법을 제안한다. 제안하는 방법은 랜덤워크 확률 모델을 이용하여 각 화소들이 초기 깊이값과 같을 확률값을 정의하여 가장 높은 확률을 가지는 초기 깊이값을 나머지 화소들에 복사한다. 제안한 방법은 인접한 화소들만을 이용하는 것이 아니라 경로를 따라 비용을 계산함으로써, 여러 화소에 걸친 색상의 변화율이 고려되어 물체의 경계 주변에서 색상 영역과 깊이 영상간의 경계가 일치하는 향상된 깊이 영상을 얻을 수 있다.