• 제목/요약/키워드: technique of direction

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차세대 이동통신시스템에서 Location Service를 위한 신호도착방향 추정기법 (Estimation Technique of Direction of Arrival for Location Service in the next Generation Mobile Communication System)

  • 이성로;최명수;김철희;안동순;김종화
    • 한국통신학회논문지
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    • 제28권5A호
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    • pp.284-293
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    • 2003
  • Location Service는 주로 위성을 이용한 GPS 방법에 의해 이루어진다. 그러나 스마트안테나를 쓰는 차세대이동통신시스템에서는 신호도착방향(DOA: Direction Of Arrival) 추정기법을 써서 Location Service가 가능하다. 본 논문에서는 차세대이동통신시스템에서 Location Service를 위한 DOA 추정기법에 관해 연구하고 타당성을 컴퓨터 모의실험을 통해 알아본다. 먼저, 직교하는 수직$.$수평 배열처리기를 써서 퍼진신호원의 DOA 추정문제를 다룬다. 수직배열처리기에서 수직 방향의 DOA를 추정한 다음 수평배열처리기에서 순차적으로 수평방향의 DOA를 추정한다. 다음으로, 3개의 스마트안테나를 이용하여 특정 신호원의 Location Service를 수행하는 과정을 컴퓨터 모의실험으로 보임으로서 제안된 DOA 추정기법이 차세대 이동통신시스템에서 Location Service를 위해 쓰일 수 있다는 타당성을 고찰한다.

Apollonius Circle 기법을 활용한 드론 방향탐지 연구 (A Study on the Direction finding of Drones Using Apollonius Circle Technique)

  • 최홍락;정원호;김경석
    • 한국인터넷방송통신학회논문지
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    • 제18권3호
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    • pp.83-92
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    • 2018
  • 본 논문은 빠르게 확대되고 있는 산업으로 각광 받고 있는 드론을 활용하여 특정 신호를 발생하는 목표물의 위치를 추정하고자 Apollonius Circle 기법을 활용하였다. 기존의 방향탐지 방법은 지상에서 차량을 통해 실시하거나 높은 위치에 안테나를 설치하여 목표물의 위치를 탐지했지만 기존의 방향탐지 방법은 LOS 신호 수신 환경을 구성하기 어렵고 또한 장비의 무게와 크기 때문에 이동 측정이 어렵다. 그러나 드론을 활용한 방향탐지는 높은 고도에서 비행하는 드론을 이용해 LOS 신호 수신 환경을 구성 및 이동 측정이 쉽다. 본 연구에서는 지상 방향탐지의 측정데이터를 이용하여 드론의 신호 수신환경을 3차원 800MHz Path-Loss Model를 활용하여 신호를 재구성하여 드론 수신 Power로 재구성하였으며 목표물의 위치를 추정하고자Apollonius Circle 기법을 활용하여 목표물의 위치를 추정하는 시뮬레이션을 구성하였다. 시뮬레이션은 지상 방향탐지와 드론 방향탐지를 구성하여 목표물의 위치추정 성능을 분석하였다.

Modelling the dispersion of a tracer gas in the wake of an isolated low-rise building

  • Quinn, A.D.;Wilson, M.;Reynolds, A.M.;Couling, S.B.;Hoxey, R.P.
    • Wind and Structures
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    • 제4권1호
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    • pp.31-44
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    • 2001
  • Mean concentrations of ammonia gas released as a tracer from an isolated low-rise building have been measured and predicted. Predictions were calculated using computational fluid dynamics (CFD) and two dispersion models: a diffusion model and a Lagrangian particle tracking technique. Explicit account was taken of the natural variation of wind direction by a technique based on the weighted summation of individual steady state wind direction results according to the probability density function of the wind direction. The results indicated that at distances >3 building heights downstream the weighted predictions from either model are satisfactory but that in the near wake the diffusion model is less successful. Weighted solutions give significantly improved predictions over unweighted results. Lack of plume spread is identified as the main cause of inaccuracies in predictions and this is linked to inadequate resolution of flow features and mixing in the CFD model. Further work on non-steady state simulation of wake flows for dispersion studies is recommended.

3-D 지층의 굴절 및 반사 주시곡선 해석 연구 (A Study on Interpretation of Seismic Refraction and Reflection Traveltime Curves in 3-D Layers)

  • 양승진;유해수;박석재
    • 자원환경지질
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    • 제25권1호
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    • pp.79-85
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    • 1992
  • An Interpretation technique is presented to determine strike, dip, velocity and depth of 3-D planar layers from refraction or reflection traveltime curve. This interpretation technique determines the direction of emerging ray from the slope of the traveltime curve and traces the emerging ray to the refractor or reflector. The ray direction in the last layer is used to decide the normal vector to the refractor or reflector from whick its dip, strike and velocity are calculated. The vertical depth to the refractor or reflector is computed by using the intercept or zero-offset time and the ray direction in each layer. Some tests on the interpretation method are performed for the sysnthetic traveltimes generated in 3-D model layers and show that the paramerters of the model layers are accurately determined.

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Magnitude Estimation기법을 이용한 설계대안의 평가 (Evaluating design alternatives based on magnitude estimation)

  • 한성호;정의승;정무영;박성준;곽지영;최필성
    • 대한인간공학회지
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    • 제12권2호
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    • pp.3-13
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    • 1993
  • A psychophysical measurement technique called "magnitude estimation" was used to evaluate several interior design alternatives for a high speed train. Pas- senger activity, seat direction, and passenger age were manipulated by using a three factor within-subjects experimental design. During the experiment, two dependent measures, a line length and a numerical estimate for each alternative design were collected to validate the experimental procedures. The results showed that pasnger seats arranged in the same direction as the running direction of the train was favored nine times more than the opposite. Also, the subjects preferred listening to music in a coach train to the other activities such as reading newspaper, watching a movie, and resting. This paper demonstrates that a psychophysical technique can be sued in the design of a development process, especially when it is difficult to quantify design variables such as subjective opinion or preference, etc.

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Three-Dimensional Self-Assembled Micro-Array Using Magnetic Force Interaction

  • Park, Yong-Sung;Kwon, Young-Soo;Eiichi Tamiya;Park, Dae-Hee
    • KIEE International Transactions on Electrophysics and Applications
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    • 제3C권5호
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    • pp.182-188
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    • 2003
  • We have demonstrated a fluidic technique for self-assembly of microfabricated parts onto substrate using patterned shapes of magnetic force self-assembled monolayers (SAMs). The metal particles and the array were fabricated using the micromachining technique. The metal particles were in a multilayer structure (Au, Ti, and Ni). Sidewalls of patterned Ni dots on the array were covered by thick negative photoresist (SU-8), and the array was magnetized. The array and the particles were mixed in buffer solution, and were arranged by magnetic force interaction. Binding direction of the metal particle onto Ni dots was controlled by multilayer structure and direction of magnetization. A quarter of total Ni dots were covered by the particles. The binding direction of the particles was controllable, and condition of particles was almost even with the Au surface on top. The particles were successfully arranged on the array.

Inverse Analysis of Ultrasonic Signals of Ceramics Based on Ultrasonic Self-Compensating Technique

  • Lee Joon-Hyun;Cheng Ansheng
    • Journal of Mechanical Science and Technology
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    • 제20권2호
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    • pp.185-190
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    • 2006
  • An ultrasonic self-calibrating technique for the characterization of a ceramic which was fabricated by change pressing time during the HIP process has been applied by using the ratio of the reflection and transmission coefficients of normal incidence longitudinal waves. The ratio is self-compensated, in that it is independent of the characteristics for transmission and reception of ultrasound by the transducer and the condition of the couplant. The insensitive direction in parameter space is defined as the direction in which the variation of the ratio to changes of two parameters vanishes. For inverse problem the distribution of minima in an error surface is investigated.

연강 용접열영향부의 소성변형거동에 관한 연구 1 (A Study on the Behaviour of Plastic Deformation in Weld HAZ of Mild Steel)

  • 박창언;정세희
    • Journal of Welding and Joining
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    • 제7권4호
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    • pp.38-45
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    • 1989
  • In this study, in order to evaluate the shape and the size of the plastic zone at the notch tip before stable crack growth, a newly developed technique for plastic strain measurement, that is, the recrystallization-etching technique was applied to observe the intense strain zone at the notch tip of weld HAZ. 1) The recrystallized specimens showed that the amount of the intense strain zone, more than 20% plastic zone, was quantitatively observed as the plane strain state during the growth of the plastic zone. 2) The behavior of plastic deformation at midsection are different for parent and weld HAZ. In addition, the micro crack initiation occurs at midsection, parent and weld HAZ when the crack opening displacement(COD) value is .delta.$_{t}$=0.4mm. 3) The plastic zone for parent proceeds in the forward direction at notch tip and for weld HAZ in the right and left direction at the notch tip. 4) The relation between plastic strain energy(Wp) and COD(.delta.$_{t}$) depended on yield stress, gradient and plastic strain size.ize.

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온라인 L1 최적화를 통한 탐색기 비정렬 효과 제거 기법 (Optical Misalignment Cancellation via Online L1 Optimization)

  • 김종한;한유덕;황익호
    • 전기학회논문지
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    • 제66권7호
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    • pp.1078-1082
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    • 2017
  • This paper presents an L1 optimization based filtering technique which effectively eliminates the optical misalignment effects encountered in the squint guidance mode with strapdown seekers. We formulated a series of L1 optimization problems in order to separate the bias and the gradient components from the measured data, and solved them via the alternating direction method of multipliers (ADMM) and sparse matrix decomposition techniques. The proposed technique was able to rapidly detect arbitrary discontinuities and gradient changes from the measured signals, and was shown to effectively cancel the undesirable effects coming from the seeker misalignment angles. The technique was implemented on embedded flight computers and the real-time operational performance was verified via the hardware-in-the-loop simulation (HILS) tests in parallel with the automatic target recognition algorithms and the intra-red synthetic target images.