• 천문학회보
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• 제38권1호
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• pp.29.1-29.1
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• 2013

We investigate the direct determination of expansion history using redshift distortions without plugging into detailed cosmological parameters. The observed spectra in redshift space include a mixture of information: fluctuations of density-density and velocity-velocity spectra, and distance measures of perpendicular and parallel components to the line of sight. Unfortunately it is hard to measure all the components simultaneously without any specific prior assumption. The degeneracy breaking, between the effect of cosmic distances and redshift distortions for example, depends on the prior we assume. An alternative approach is to utilize the cosmological principle inscribed in the heart of the Friedmann-Lematre-Robertson-Walker (hereafter FLRW) universe, that is, the specific relation between the angular diameter distance and the Hubble parameter, in this degeneracy breaking.

• Journal of information and communication convergence engineering
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• 제9권1호
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• pp.105-109
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• 2011

In this paper, we study the dominating-free sest which is defined as follows: k points called servers and n points called clients in the plane are given. For a point p in the plane is said to be dominated by a client c if for every server s, the distance between s and p is greater than the distance between s and c. The dominating-free set is the set of points in the plane which aren't dominated by any client. We present an O(nklogk+$n^2k$) time algorithm for computing the dominating-free set under the $L_1$-metric. Specially, we present an O(nlogn) time algorithm for the problem when k=2. The algorithm uses some variables and 1-dimensional arrays as its principle data structures, so it is easy to implement and runs fast.

• 충청수학회지
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• 제35권3호
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• pp.227-234
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• 2022

Let 𝔽_q be a finite field with odd q elements. In this article, we prove that if E ⊆ 𝔽^d_q, d ≥ 2, and |E| ≥ q, then there exists a set Y ⊆ 𝔽^d_q with |Y| ~ q^d such that for all y ∈ Y, the number of distances between the point y and the set E is ~ q. As a corollary, we obtain that for each set E ⊆ 𝔽^d_q with |E| ≥ q, there exists a set Y ⊆ 𝔽^d_q with |Y| ~ q^d so that any set E ∪ {y} with y ∈ Y determines a positive proportion of all possible distances. The averaging argument and the pigeonhole principle play a crucial role in proving our results.

• Journal of Information Processing Systems
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• 제20권2호
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• pp.185-199
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• 2024

In this paper, an improved automated spectral clustering (IASC) algorithm is proposed to address the limitations of the traditional spectral clustering (TSC) algorithm, particularly its inability to automatically determine the number of clusters. Firstly, a cluster number evaluation factor based on the optimal clustering principle is proposed. By iterating through different k values, the value corresponding to the largest evaluation factor was selected as the first-rank number of clusters. Secondly, the IASC algorithm adopts a density-sensitive distance to measure the similarity between the sample points. This rendered a high similarity to the data distributed in the same high-density area. Thirdly, to improve clustering accuracy, the IASC algorithm uses the cosine angle classification method instead of K-means to classify the eigenvectors. Six algorithms-K-means, fuzzy C-means, TSC, EIGENGAP, DBSCAN, and density peak-were compared with the proposed algorithm on six datasets. The results show that the IASC algorithm not only automatically determines the number of clusters but also obtains better clustering accuracy on both synthetic and UCI datasets.

• 대한교통학회지
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• 제32권5호
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• pp.441-451
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• 2014

본 연구는 도로 기상정보 시스템(RWIS : Road Weather Information System)에서 수집되는 시정거리와 차량검지기(VDS : Vehicle Detection System)에서 수집되는 속도 자료를 이용하여 교통류 안전성을 판단하였다. 교통류의 안전성 측면에서 시정거리(VD : Visibility Distance)가 정지시거(SSD : Stopping Sight Distance)보다 길어야 이벤트 발생 시 안전하게 정지하거나 위험한 상황을 회피할 수 있다. 운전자에게 사고예방을 위한 능동적 대응이 가능하도록 하는 가치있는 정보를 제공하기 위해 최근접이웃 예측기법(KNN : K-Nearest Neighbors Method)을 활용하였다. 또한, 교통류 안전성에 대한 운전자의 이해도 증진 및 객관성을 위하여 안전성 지표(LOHSI : Level of Hazardous Spacing Index)를 제시하였다. 본 연구결과는 교통류의 안전성 향상을 위한 효율적인 교통운영을 지원 할 수 있을 것이다.

• 전기전자학회논문지
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• 제22권4호
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• pp.922-932
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• 2018

방사형 거리 센서는 측량 및 자율 주행에 널리 사용된다. 이러한 센서의 작동 원리 및 적용 방법의 교육이 필요하다. 상용 방사형 거리 센서의 저성능화를 통한 저가화가 계속되고 있지만, 교육 목적으로 사용하기에는 여전히 고가이다. 본 논문에서는 교육용 로봇에 활용할 수 있는 저가의 포토트랜지스터의 방사형 배열을 이용한 물체추적기능을 갖는 거리 센서 모듈을 제안한다. 제안하는 방법은 포토트랜지스터를 180도 범위의 배열로 배치하여 빠르게 움직이는 물체의 위치를 즉시 감지할 수 있으며 서보 모터를 사용한 센서 회전으로 감지 각도 범위를 향상하고 물체를 추적한다. 제안된 센서의 스캔 속도는 상업용 거리 센서보다 50~200배 빨라서 1ms의 제어 루프를 가지는 고성능의 교육용 모바일 로봇에 적용할 수 있다.

• Journal of the Korean Data and Information Science Society
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• 제14권1호
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• pp.131-141
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• 2003

In this paper, we prove that multi-variate fuzzy polynomials are universal approximators for multi-variate fuzzy functions which are the extension principle of continuous real-valued function under $T_W-based$ fuzzy arithmetic operations for a distance measure that Buckley et al.(1999) used. We also consider a class of fuzzy polynomial regression model. A mixed non-linear programming approach is used to derive the satisfying solution.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.88-93
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• 1993

This paper introduces an ARV(Autonomous Road Vehicle) system which can run on orads without help of a driver by detecting road boundaries through computer vision. This vehicle can also detect obstacles in front through sonar sensors and infrared sensors. This system largely consists of a handle steering module and a braking module. From road boundaries, the steering module determines handle turn angle. The braking module stops or decelerates to avoid collision depending on the relative speeds and distance to the obstacles detected by different sensors. This ARV system has been implemented in a small jeep and can run 30-40 km/h city traffic. In this paper, we illustrate the structure of the ARV systems and its operation principle.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.1145-1155
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• 2007

In this paper, we consider the permutation tests for the multivariate data under the two-sample problem setting. We review some testing procedures, which are parametric and nonparametric and compare them with the permutation ones. Then we consider to try to apply the permutation tests to the multivariate data having the continuous and discrete components together by choosing some suitable combining function through the partial testing. Finally we discuss more aspects for the permutation tests as concluding remarks.

• 대한전자공학회논문지
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• 제24권5호
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• pp.762-768
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• 1987

The capacitive transducers, which are used of the principle of capacitance changes by means of the variation of distance between electrodes, are usually utilized for measurement of small displacements. But the measurement ranges of this method are limited. In this study, the measurement ranges are extended by using the variation method of the surface area of electrodes. Thus the capacitive transducer and signal conditioner, which are having the capability of measurement range of 25mm and resolution of 0.1\ulcorner, have developed, and its environmental characteristics are also tested.