• Title/Summary/Keyword: 상대 거리 측정

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A Study on Dynamic Trigger Threshold in Indoor Positioning System (실내 위치 추정 시스템에서의 동적 트리거 임계값에 관한 연구)

  • Oh, Jongtaek
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.6
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    • pp.155-161
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    • 2015
  • As the popularity of the smartphone becomes increase, indoor smartphone positioning technology has been actively studied. The acoustic signal generated from the smartphone is received from the several microphones at the relative positioning system, and the trigger signal is proposed to mitigate the multipath effect and the effect is verified. But for the simple trigger method, there would be error occurred according to the variation of the distance or surrounding noise. In this paper, in order to resolve the problems, the dynamic trigger threshold technology is proposed and its effect is verified by the experiment.

A Study on the Atomization Characteristics of the Ultrasonic-Energy-Irradiation High Viscosity Biodiesel Blended Fuel (초음파 에너지 조사 고 점도 바이오디젤 혼합연료의 미립화 특성에 관한 연구)

  • Song Yong-Seek;Yang In-Kwon;Kim Bong-Seock;Ryu Jung-In
    • Journal of Energy Engineering
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    • v.13 no.4
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    • pp.235-241
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    • 2004
  • This experiment was undertaken to investigate the atomization characteristics of the high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Test fuels were conventional diesel fuel and biodiesel one. We compared to the characteristics of viscosity and surface tension, SMD between high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension were measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600c. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy irradiation situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than those of the conventional situation.

축방향 가상음극발진기를 이용한 고출력 마이크로파의 전자기기 효과 연구

  • Byeon, Yong-Seong;Song, Gi-Baek;Choe, Eun-Ha
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.434-434
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    • 2010
  • Axial type 가상음극발진기를 이용하여 전극의 기하학적 구조와 고출력 마이크로파의 출력 특성을 분석하고, 최대 파워의 조건에 대한 전자기기 효과를 알아보았다. 고출력 마이크로파 발생 장치인 Vircator는 강렬한 상대론적 전자빔 발생장치로 최대전압 600 kV, 최대전류 88 kA, 펄스폭 60 ns의 특성을 가진다. Anode와 cathode의 간격은 4 mm로 최적화 하였고, 이 조건에서 마이크로파의 출력 특성을 분석하여 보았을 때 WR-137 수신안테나에서 최대 출력143 MW와 5.4 GHz의 진동수를 측정하였다. 출력 효율을 증가시키기 위해서 도파관 중앙에 폭이 10 mm인 반사판을 사용하였고, 그 결과 반사판이 공진구조에 기여하여 정상파(standing wave)를 형성하여 마이크로파 출력 효율 향상하여 WR-137에서 최대 549 MW의 출력을 보였다. 향상된 마이크로파의 출력을 이용하여 각도와 거리를 변화해 가며 컴퓨터와 전자소자로 제작된 회로에 대해 전자기기 효과 실험을 실시하였다. 그 결과 컴퓨터의 경우 $0^{\circ}$ 1 m에서 hard kill 상태가 되었다. 전자소자 회로의 경우는 $0^{\circ}$ 30 cm에서 hard kill의 상태로 되었다. 또한 면적 대비 출력 파워로 비교 했을 경우 약 $0.484\;{\mu}J$의 마이크로파의 영향임을 확인할 수 있었다.

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Implementation and Performance Evaluation of a Precision Localizing Device for Hyperloop Pods Driving at Ulta-High Speeds (초고속주행 하이퍼루프 포드의 정밀 위치측정 장치 구현 및 성능평가)

  • Ok, Min-Hwan;Choi, Su-Yong;Choe, Jae-Heon;Lee, Kwan-Sup
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.13 no.5
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    • pp.443-451
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    • 2020
  • A futuristic locomotion system called Hyperloop is projected for driving at ulta-high speed, levitated in the tube. In hyperloop localization of pods on the linear synchronous motor is essential for pod driving. precision localization is required for acceleration and deceleration of pods driving at speed above 1,000km/h, and also required for adjusting the pod speed driving at this very-high speed to maintain inter-vehicle distance. In this work, a new scale of localization is challenged by modified laser surface velocimeter. In acceleration the speed of a virtual pod is calculated along its displacement measured by laser reflection. Under the requirement of precise localization of the pod driving at ultra-high speed, a displacement measurement device, which detects the difference in reflections from tiles passing by the pod, is developed and evaluated through performance test. Tests of pod speeds below 500km/h have showed exact localization results of the precision in centimeters, and tests of pod speeds above 500km/h have showed localization with very low error rates under 0.1%. For the measurement above 500km/h, future works would pursue the error rate converges to zero.

Investigation of elementary teachers' perspectives on science inquiry teaching (과학 탐구 지도에 대한 초등학교 교사들의 인식 조사)

  • Jeon, Kyungmoon
    • Journal of Science Education
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    • v.39 no.2
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    • pp.267-277
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    • 2015
  • This study explored elementary school teachers' perspectives on science inquiry teaching. First, an open-ended questionnaire was administered to elicit teachers' experiences of their approach to inquiry teaching. These self-reported approaches revealed three conceptions of teaching for inquiry learning in science: 'science process skills-centered' category focused on observing, classifying, measuring, and fair testing; 'generating scientific questions' category focused on students' question-generating; and 'illustrate concept and/or content' category focused on science content demonstration by making use of experimental procedures to obtain expected results. Second, teachers were asked to place 18 activity cards either close to or further from an 'inquiry-based science classroom' card. The relative distances from the activity card to the central classroom card were measured. The teachers perceived that students' activity of 'designing and implementing appropriate procedures' was the most important in supporting an inquiry-based science classroom. Understanding teachers' views has implications for both the enactment of inquiry teaching in the classroom as well as the uptake of new teaching behaviors during professional development.

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Hybrid Stress Analysis around a Circular Hole in a Tensile Plate by Use of Phase Shifting Photoelasticity (광탄성 위상이동법에 의한 인장시편 원형 구멍주위 하이브리드 응력해석)

  • Baek, Tae-Hyun;Lee, Choon-Tae;Yang, Min-Bok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.1
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    • pp.15-22
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    • 2007
  • A hybrid experimental-numerical method is presented for determining the stresses around a circular hole in a finite-width, tensile loaded plate. Measured fringe orders along straight lines provided the input information on the external boundary of the hybrid element. In order to see the effects of varying stress field, different numbers of terms in a power-series representation of the complex type conformal mapping stress function were tested. For qualitative comparison, actual isochromatic fringes were compared with reconstructed theoretical fringes using stress-optic law. For quantitative comparison, relative errors and standard deviations with respective to relative errors were analyzed for all measured points by changing the number of terms of stress function. The hybrid results are highly comparable with those predicted by FEA. The results show that this approach is effective and promising because isochromatic data along the straight lines in photoelasticity can be conveniently measured by use of phase shifting photoelasticity.

A new method to estimate the striking velocity for small caliber projectiles (소구경 탄자의 충돌속도 추정방법 제안)

  • Yoo, Sangjun;Kim, Jeyong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.3
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    • pp.1288-1293
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    • 2014
  • This paper proposes a new method to estimate the striking velocity for ballistic limit velocity in MIL-STD-662F. The method from MIL-STD-662F needs relative air density, drag coefficient, form factor, ballistic coefficient for estimating striking velocity. So precedent studies are essential. However, the new method can estimate striking velocity only using measured velocities and distance between the screen and the target. To prove new method, we compared estimation of striking velocity from both the new method and the method from MIL-STD-662F on the basis of datain PRODAS. The new method shows bigger errors in some velocity ranges. But it could still calculate ballistic limit velocity. It also shows smaller errors in most velocity ranges.

A Study on Development of the 3D Modeling System for Earthwork Environment (토공 작업환경의 3차원 모델링 시스템 개발에 관한 연구)

  • Yoo, Hyun-Seok;Chae, Myung-Jin;Kim, Jung-Yeol;Cho, Moon-Young
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • 2007.11a
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    • pp.977-982
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    • 2007
  • There have been many efforts in automatic object recognition using computing technologies. Especially in the development of automated construction equipment, automatic object recognition is very important issue for the proper equipment maneuvering. 3D laser scanning, which uses (time-of-flight) method to construct the 3-dimensional information, is applied to the civil earth work environment for its high accuracy, quick data collection, and object recognition capability that will be developed by the authors in the future. The 3D earth model is also used as a fundamental information for intelligent earth work task planning. This paper presents the analysis of the 3D laser scanner market and selection of the most optimum 3D scanner for the intelligent earth work planning. As well as the hardware configuration for the automated 3D earth modeling is developed but also the software structure and detailed user interface are designed in this research. In addition, it is presented in this paper that the accuracy comparison test between TotalStation(R) which is a traditional survey tool and ScanStation(R). The accuracy test is done by relative distance measurement using known targets.

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Model Tests on Ground Deformation during Trench Excavation for Diaphragm Walls (지중연속벽 시공을 위한 트렌치 굴착시 지반변형에 관한 모형실험)

  • Hong, Won-Pyo;Lee, Moon-Ku;Lee, Jae-Ho
    • Journal of the Korean Geotechnical Society
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    • v.22 no.12
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    • pp.77-88
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    • 2006
  • A series of model tests were performed to investigate the ground deformation during trench excavation for diaphragm walls. An apparatus was manufactured to observe the failure pattern of a slurry-supported trench in sandy ground. Ground deformations including settlement and lateral displacement of the surrounding ground adjacent to the trench were carefully monitored during excavation. Experimental observations indicated that the settlement of the adjacent ground increased with closing to the trench. Especially, the considerable settlement occurred at the distance which was equal to 40% of the excavation depth. And, the higher settlement was obtained when the relative density of ground was looser and the ground water table was higher. Also, the lateral wall face of excavated trench was bulged with lowering the slurry level In stages and then the upper part of trench failed finally. The envelope of ground surface settlement could be represented as a hyperbolic line and the measured settlement was smaller than those predicted by Clough and O'Rourke (1990).

The Gradient Variation of Thermal Environments on the Park Woodland Edge in Summer - A Study of Hadongsongrim and Hamyangsangrim - (여름철 공원 수림지 가장자리의 온열환경 기울기 변화 - 하동송림과 함양상림을 대상으로 -)

  • Ryu, Nam-Hyong;Lee, Chun-Seok
    • Journal of the Korean Institute of Landscape Architecture
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    • v.43 no.6
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    • pp.73-85
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    • 2015
  • This study investigated the extent and magnitude of the woodland edge effects on users' thermal environments according to distance from woodland border. A series of experiments to measure air temperature, relative humidity, wind velocity, MRT and UTCI were conducted over six days between July 31 and August 5, 2015, which corresponded with extremely hot weather, at the south-facing edge of Hadongsongrim(pure Pinus densiflora stands, tree age: $100{\pm}33yr$, tree height: $12.8{\pm}2.7m$, canopy closure: 75%, N $35^{\circ}03^{\prime}34.7^{{\prime}{\prime}}$, E $127^{\circ}44^{\prime}43.3^{{\prime}{\prime}}$, elevation 7~10m) and east-facing edge of Hamyangsangrim (Quercus serrata-Carpinus tschonoskii community, tree age: 102~125yr/58~123yr, tree height: tree layer $18.6{\pm}2.3m/subtree$ layer $5.9{\pm}3.2m/shrub$ layer $0.5{\pm}0.5m$, herbaceous layer coverage ratio 60%, canopy closure: 96%, N $35^{\circ}31^{\prime}28.1^{{\prime}{\prime}}$, E $127^{\circ}43^{\prime}09.8^{{\prime}{\prime}}$, elevation 170~180m) in rural villages of Hadong and Hamyang, Korea. The minus result value of depth means woodland's outside. The depth of edge influence(DEI) on the maximum air temperature, minimum relative humidity and wind speed at maximum air temperature time during the daytime(10:00~17:00) were detected to be $12.7{\pm}4.9$, $15.8{\pm}9.8$ and $23.8{\pm}26.2m$, respectively, in the mature evergreen conifer woodland of Hadongsongrim. These were detected to be $3.7{\pm}2.2$, $4.9{\pm}4.4$ and $2.6{\pm}7.8m$, respectively, in the deciduous broadleaf woodland of Hamyansangrim. The DEI on the maximum 10 minutes average MRT, UTCI from the three-dimensional environment absorbed by the human-biometeorological reference person during the daytime(10:00~17:00) were detected to be $7.1{\pm}1.7$ and $4.3{\pm}4.6m$, respectively, in the relatively sparse woodland of Hadongsongrim. These were detected to be $5.8{\pm}4.9$ and $3.5{\pm}4.1m$, respectively, in the dense and closed woodland of Hadongsongrim. Edge effects on the thermal environments of air temperature, relative humidity, wind speed, MRT and UTCI in the sparse woodland of Hadongsongrim were less pronounced than those recorded in densed and closed woodland of Hamyansangrim. The gradient variation was less steep for maximum 10 minutes average UTCI with at least $4.3{\pm}4.6m$(Hadongsongrim) and $3.5{\pm}4.1m$(Hamyansangrim) being required to stabilize the UTCI at mature woodlands. Therefore it is suggested that the woodlands buffer widths based on the UTCI values should be 3.5~7.6 m(Hamyansangrim) and 4.3~8.9(Hadongsongrim) m on each side of mature woodlands for users' thermal comfort environments. The woodland edge structure should be multi-layered canopies and closed edge for the buffer effect of woodland edge on woodland users' thermal comfort.