• Title/Summary/Keyword: Relative distance

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Analysis of Linear and Nonlinear Relative Orbit Dynamics for Satellite Formation Flying (선형 및 비선형 상대궤도운동 모델들의 정확도 분석)

  • Park, Han-Earl;Park, Sang-Young;Lee, Sang-Jin;Choi, Kyu-Hong
    • Journal of Astronomy and Space Sciences
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    • v.26 no.3
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    • pp.317-328
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    • 2009
  • Relative dynamic models of satellites which describe the relative motion between two satellites is fundamental for research on the formation flying. The accuracy of various linearized or nonlinear models of relative motion is analyzed and compared. A 'Modeling Error Index (MEI)' is defined for evaluating the accuracy of models. The accuracy of the relative dynamic models in various orbit circumstance are obtained by calculating the modeling error with various eccentricities of the chief orbit and distances between the chief and the deputy. It is found that the modeling errors of the relative dynamic models have different values according to the eccentricity, J2 perturbation, and the distance between satellites. Since the evaluated accuracy of various models in this paper means the error of dynamic models of the formation flying, the results of this paper are very useful for choosing the appropriate relative model of the formation flying mission.

A STUDY ON THE CHANGES IN POLYMERIZATION OF LIGHT-ACTIVATED COMPOSITE RESIN WITH VARIOUS EXPOSURE TIME AND DISTANCE (광중합형 복합레진의 중합시간과 거리에 따른 중합도의 변화)

  • Ahn, Myung-Ki;Jeong, Tae-Sung;Kim, Shin
    • Journal of the korean academy of Pediatric Dentistry
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    • v.28 no.2
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    • pp.293-299
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    • 2001
  • The aim of this study was to evaluate the effect of the distance of the light tip to the surface of restoration and exposure time on the polymerization of surface and 2mm below the surface of light-activated composite resins. Two light-activated composite resins were used. From the experiment, the following results were obtained. 1. Relative light intensity rapidly decreased when distance of the light tip to the surface of material is more than 2mm(p<0.05). 2. In all groups, microhardness was increased according to the increase of relative light intensity and exposure time(p<0.05). 3. The distance of the light tip to the surface of restoration and exposure time more affected 2mm below the surface rather than the surface(p<0.05). 4. Although exposure time was increased, difference of microhardness of the 2mm below the surface with the distance of the light tip to the surface of restoration was relatively high in Z100 between below 4mm and other groups and Z250 between below 2mm and other groups(p<0.05).

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Distribution of Wave Forces at Points on a Vertical Structure of Semi-Infinite Breakwater Considering Diffraction (회절을 고려한 반무한방파제 형식의 직립구조물에 작용하는 지점별 파력 분포)

  • Jung, Jae-Sang;Lee, Changhoon;Cho, Yong-Sik
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.4
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    • pp.240-249
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    • 2016
  • In this study, we investigated wave force distribution at points on a vertical structure of semi-infinite breakwater considering diffraction. Wave forces of monochromatic and random waves on a vertical structure are studied considering diffractions in front and lee side of the breakwater for non-breaking wave condition. We selected width of breakwater are 0 for reference condition. In monochromatic wave case, relative wave force becomes 0 on the head of the breakwater by acting incident wave force and diffracting wave force simultaneously and oscillating patterns of relative wave force occurs based on 1.0 as distance from the head increases. Relative wave force of monochromatic waves decreases as incident wave angle increases. Relative wave force of random waves is defined by using ratio of root mean square and wave force spectrum in this study. The case considering random phase of each wave components are compared to the case which don't consider random phase and both results are almost similar. Relative wave force of random waves is also 0 near the head of the breakwater likewise monochromatic wave. Oscillating pattern of relative wave force of random waves becomes relatively weaker for composition of each wave components as distance from the head increases.

Similarity-Based Subsequence Search in Image Sequence Databases (이미지 시퀀스 데이터베이스에서의 유사성 기반 서브시퀀스 검색)

  • Kim, In-Bum;Park, Sang-Hyun
    • The KIPS Transactions:PartD
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    • v.10D no.3
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    • pp.501-512
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    • 2003
  • This paper proposes an indexing technique for fast retrieval of similar image subsequences using the multi-dimensional time warping distance. The time warping distance is a more suitable similarity measure than Lp distance in many applications where sequences may be of different lengths and/or different sampling rates. Our indexing scheme employs a disk-based suffix tree as an index structure and uses a lower-bound distance function to filter out dissimilar subsequences without false dismissals. It applies the normaliration for an easier control of relative weighting of feature dimensions and the discretization to compress the index tree. Experiments on medical and synthetic image sequences verify that the proposed method significantly outperforms the naive method and scales well in a large volume of image sequence databases.

A Multi-Resolution Distance Measure in Two Dimensional Images Using Proposed Grey Block Distance Algorithms (제안된 GBD 알고리즘을 이용한 이차원 영상에서의 다중해상도 거리 측정)

  • Hong, Jun-Sik;Jung, Soon-Won
    • Proceedings of the Korea Contents Association Conference
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    • 2006.05a
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    • pp.392-397
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    • 2006
  • In this paper, we have proposed a revised GBD algorithm to make a relative identification more easily between 2-Dimensional images being compared with the well-known GBD(Grey Block Distance) algorithm. The method proposed here can measure the information about both the whole images and partial image. Also it can improve the performance of the existing GBD algorithm to do not loose the information of the partial image which has been changed rapidly in the 2-D image application. From the results of the experimental simulation we can say that the proposed method can be identified 2-D images more easily than that of the existing GBD algorithm.

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Breakdown Characteristics of Air in the Gap between Line Conductor and Plane Electrode in Case of Combustion Flame on the Plane Electrode (선도체 대 평면전극 갭에서 평면전극에 연소화염 존재시 대기의 절연파괴 특성)

  • Kim, In-Sik
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.4
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    • pp.73-80
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    • 2013
  • Breakdown characteristics of air in the vertical arrangement of line conductor and plane electrode in case of combustion flame on the plane electrode are examined by the application of AC. and DC voltages to the gap. In order to investigate the effect of paraffin flame on the breakdown characteristics of air, flashover voltages are measured according to the variation of the gap length and the horizontal distance between the flame and the line conductor. As the result of the experiment, flashover voltages are substantially lowered down to 29.8% in case of the AC voltage, and 16.1% in case of the negative DC voltage, when in the presence of the flame. from 100% when in the absence of flame. Flashover voltages of air in the range of smaller than 3㎝ at the horizontal distance are increased in the proportion of the gap length and the horizontal distance in case of both AC and negative DC voltages. But before the flashover occurs, the flame is extinguished by such corona wind that is produced from the line conductor when the gap length and the horizontal distance reach to a certain degree. The effect of relative air density and the phenomenon of thermal ionization are analysed as the reduction factors of flashover voltages, due to high temperature of the flame.

Cultural Characteristics and Product Appeals Reflected on Fashion Ads (패션상품의 광고에 나타난 문화적 특성과 소구유형)

  • 전양진
    • Journal of the Korean Society of Clothing and Textiles
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    • v.26 no.8
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    • pp.1196-1204
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    • 2002
  • This research was to see if the fashion product ads are standardized or differentiated, and to find what were the determinants if any differentiation existed. The purpose of this study was to identify cultural characteristics significant on marketing fashion produce. In addition, the relative importance of product appeals between rational and emotional in the fashion ads was examined. Hofstede's(l991) three cultural characteristics dimensions such as individualism-collectivism, power distance, masculinity-femininity were used. Content analysis was applied in the study. Magazine ads of apparel, cosmetics and accessories were collected from France, Japan, Korea and the US in 1999-2000. Cultural characteristics of the fashion ads were evaluated and compared in terms of country, product type and product involvement. Also ten consumption appeals were examined for county and product type. ANOVA, Duncan test and $X^2$ test were applied to analyze data. The results were shown as follows: First, all the cultural characteristics such as individualism-collectivism, power distance, and femininity-masculinity were different among countries. Second, two product appeals were significantly different among countries. Hedonic appeals were dominant fur France and the US while those were not for Korea and Japan. Third, product involvement level had significant impact on power distance characteristic and product appeals. Ads of high involvement fashion goods showed larger power distance and more emotional appeals. In conclusion, global fashion ads should be differentiated in terms of some cultural characteristics and product appeals.

Long Distance Vehicle Recognition and Tracking using Shadow (그림자를 이용한 원거리 차량 인식 및 추적)

  • Ahn, Young-Sun;Kwak, Seong-Woo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.1
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    • pp.251-256
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    • 2019
  • This paper presents an algorithm for recognizing and tracking a vehicle at a distance using a monocular camera installed at the center of the windshield of a vehicle to operate an autonomous vehicle in a racing. The vehicle is detected using the Haar feature, and the size and position of the vehicle are determined by detecting the shadows at the bottom of the vehicle. The region around the recognized vehicle is determined as ROI (Region Of Interest) and the vehicle shadow within the ROI is found and tracked in the next frame. Then the position, relative speed and direction of the vehicle are predicted. Experimental results show that the vehicle is recognized with a recognition rate of over 90% at a distance of more than 100 meters.

Study on the Wake Roll-up Behind Multiple Wings in Formation Flight (편대비행 하는 항공기 날개들에서 발생하는 후류말림 연구)

  • Han, Cheolheui
    • Journal of Institute of Convergence Technology
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    • v.10 no.1
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    • pp.1-5
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    • 2020
  • The wake shapes behind wings in formation flight are very important to the aerodynamics and performances of aircrafts. In the present study, a discrete vortex methood is extended to handle the wake rollups behind multiple wings. It was found that the relative distance between the wings and the rotational direction of the wingtip vortices have significant effect on the movement of the wingtip vortices. When the wings are close to each other, the wingtip vortices moved faster than the wings of large relative distances. The vortex pair of opposite signs generated from each wingtip has an effect of moving the wingtip vortices upward. The relative height between the wings has an effect of moving the wingtips along the centerline of each vortex. The wakeshape behind multiple wings is a function of the relative distances and thus is dependent on the configuration of the formation flight. In the futhre, a study on the vortex movement pattern will be studied.

Characteristics of Vertical Stress Distribution in Sandy Soil According to the Relative Compaction and Composition of the Soil Layer (사질토 지반의 상대다짐도 및 토층에 따른 연직지중응력 분포 특성)

  • Nam, Hyo-Seok;Lee, Sang-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.2
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    • pp.43-50
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    • 2010
  • This study was carried out to evaluate the vertical stress properties in sandy soil according to changes of foundation condition in soil bin compacted three layers. The following conclusions and comparisons have been made based on careful analysis from theoretical and experimental methods. : When sandy soil subjected to circular uniform load, the vertical stress increments ($\Delta\sigma_z$) was increased as load increasing, the maximum values of $\Delta\sigma_z$ was achieved at the point loading axis, and $\Delta\sigma_z$ was not shown over at a distance of three times of loading plate width (B). The vertical stress increments were achieved largely at 80 % relative compaction (Rc) compared to 95 % relative compaction due to stress concentration in sandy soil. When sandy soil subjected to circular uniform load, the $\Delta\sigma_z$ differences between theoretical and experimental values as load increased were more increased and its maximum differences were achieved at stress axis. When gravel surface macadamized over sandy soil subjected to load, the $\Delta\sigma_z$ was concentrated to load axis as load increasing, so that macadamization will be decreased load transmission.