• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.41-49
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• 2007

In this paper, we proposed a new ultrasonic distance measurement system with high accuracy and long range. To improve accuracy and enlarge range, the time of flight of ultrasonic is calculated by the period detecting method. In the proposed ultrasonic distance measurement system, the ultrasonic transmitter and receiver are separated but synchronized by RF(Radio frequency) module. The experiment has been implemented from short distance 1m to maximum available distance 30m. And the period detecting method is compared with the conventional threshold level method. Experimental results show the accuracy and range of the distance measurement are improved by this period detecting method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.91-96
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• 2001

Diminishing fare rate to distance is widely applied in transportation field including bus, but the decision method of diminishing rate is not established. The basic concept of diminishing fare rate to distance is that passengers have a benefit according to their travel distance. Furthermore, this can be justified in the standpoint of operator because the cost of long-distance traveller is lower than that of short-distance traveller to make same income. It is essential to introduce diminishing fare rate to distance to decide diminishing rate. We suggested methodologies regarding how to decide diminishing rate on the basis of operator costs.

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.522-529
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• 2010

Distance relay plays an important role in the protection of transmission lines. The application of flexible AC transmission systems (FACTS) devices, such as the static synchronous compensator (STATCOM), could affect the performance of the distance relay because of compensation effect. This paper analyzes the application of distance relay on the protection of a transmission line containing STATCOM. New setting principles for different protection zones are proposed based on this analysis. A typical 500 kV transmission system employing STATCOM is modeled using Matlab/Simulink. The impact of STATCOM on distance protection scheme is studied for different fault types, fault locations, and system configurations. Based on simulation results, the performance of distance relay is evaluated. The setting principle can be verified for the transmission line with STATCOM.

• Communications for Statistical Applications and Methods
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• 제16권6호
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• pp.989-995
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• 2009

Basu et al. (1998) proposed the minimum divergence estimating method which is free from using the painful kernel density estimator. Their proposed class of density power divergences is indexed by a single parameter $\alpha$ which controls the trade-off between robustness and efficiency. In this article, (1) we introduce a new large class the minimum squared distance which includes from the minimum Hellinger distance to the minimum $L_2$ distance. We also show that under certain conditions both the minimum density power divergence estimator(MDPDE) and the minimum squared distance estimator(MSDE) are asymptotically equivalent and (2) in finite samples the MDPDE performs better than the MSDE in general but there are some cases where the MSDE performs better than the MDPDE when estimating a location parameter or a proportion of mixed distributions.

• 한국정보과학회논문지:데이타베이스
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• 제31권2호
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• pp.83-90
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• 2004

본 논문에서는 순환적인 검색공간과 장애물이 존재하는 검색공간에서 객체들을 클러스터링할 때 고려해야하는 CCD(Clustering with Circular Distance) 문제와 COD(Clustering with Obstructed Distance) 문제를 연구하였다. 그리고 다차원 검색공간에서 삽입이나 삭제가 빈번히 발생하는 객체들을 효율적으로 클러스터링하기 위한 새로운 클러스터링 알고리즘을 제안하였다. 제안한 클러스터링 알고리즘에는 CCD 및 COD 문제를 해결하기 위한 거리 함수가 정의된다. 그리고 최소의 연산 시간으로 높은 공간 국부성을 갖는 클러스터들을 생성하기 위한 클러스터링 방법이 포함된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1025-1027
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• 1997

In this paper, the digital distance relay of transmission lines under fault conditions is discussed. Distance relay is used to protect transmission lines. The principle of distance relay is well-known ; the impedance measured by a relay is Proportional to the distance from the relay to the fault. Hence, by measuring the impedance, it can be determined whether the line is faulted or not. Unfortunately, the measurement of the fault distance is distorted by Mutual Coupling. To implement more reliable and practical digital distance relay, the mutual coupling effect has to be considered.

• Advances in Traditional Medicine
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• 제4권2호
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• pp.120-123
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• 2004

To test preschool children's medium- long distance stereoscopic vision normal average value, and intermittent strabismus children,s medium-long distance stereoscopic vision acuteness is the goal of this study. The software of random stereoscopic vision and graph, which is developed by Hu-Chong etc has been used, to test 414 cases normal preschool children and 19 cases intermittent exotropia childrens medium-long distance (1-5 m) stereoscopic vision (before operation and after operation). The normal average value of preschool children's medium-long distance stereoscopic vision was achieved. Intermittent exotropia children's stereoscopic vision acuteness was declined with the increase of distance. This method can provide reference as screening abnormal stereoscopic vision during scientific research and clinical work.

• 전자공학회논문지B
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• 제33B권7호
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• pp.138-146
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• 1996

In this paper, w epropose a new mehtod to represent the shape and to recognize the object. The shape description and the matching is implemented by using the distance transform on the morphological skeleton. The employed distance transform is the chamfer (3,4) distance transform, because the chamfer distance transform (CDT) has an approximate value to the euclidean distance. The 2-D object can be represented by means of the distribution of the distance transform on the morphological skeleton, the number of skeletons, the sum of the CDT, and the other features are employed as the mtching parameters. The matching method has the invariant features (rotation, translation, and scaling), and then the method is used effectively for recognizing the differently-posed objects and/or marks of the different shape and size.

• 대한전기학회논문지
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• 제43권5호
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• pp.848-860
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• 1994

Generally, to get the minimum distance between two arbitrary shapes that are composed of circular arcs and lines, we must calculate distances for all the possible pairs of the components from two given shapes. In this paper, we propose an efficient method for the minimum distance problem between two shapes by using their structural features after extracting the reduced component lists which are essential to calculate the minimum distance considering the relationship of shape location. Even though the reduced component lists may contain all the components of the shapes in the worst case, in the average we can reduce the required computation much by using the reduced component lists. This method may be efectively applied to calculating the minimum distance between two shapes which are generated by the CAD tool, like in the nesting system.

• Communications for Statistical Applications and Methods
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• 제27권6호
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• pp.589-602
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• 2020

The development of smart grids has enabled the easy collection of a large amount of power data. There are some common patterns that make it useful to cluster power consumption patterns when analyzing s power big data. In this paper, clustering analysis is based on distance functions for time series and clustering algorithms to discover patterns for power consumption data. In clustering, we use 10 distance measures to find the clusters that consider the characteristics of time series data. A simulation study is done to compare the distance measures for clustering. Cluster validity measures are also calculated and compared such as error rate, similarity index, Dunn index and silhouette values. Real power consumption data are used for clustering, with five distance measures whose performances are better than others in the simulation.