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검색결과 308건 처리시간 0.028초

전방향 이동로봇 위치제어 알고리즘과 실험적 검증 (Position Control Algorithm and Experimental Evaluation of an Omni-directional Mobile Robot)

  • 주백석;조강익;성영휘
    • 한국생산제조학회지
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    • 제24권2호
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    • pp.141-147
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    • 2015
  • In this study, a position control algorithm for an omni-directional mobile robot based on Mecanum wheels was introduced and experimentally evaluated. Multiple ultrasonic sensors were installed around the mobile robot to obtain position feedback. Using the distance of the robot from the wall, the position and orientation of the mobile robot were calculated. In accordance with the omni-directional velocity generation mechanism, the velocity kinematics between the Mecanum wheel and the mobile platform were determined. Based on this formulation, a simple and intuitive position control algorithm was suggested. To evaluate the control algorithm, a test bed composed of artificial walls was designed and implemented. While conventional control algorithms based on normal wheels require additional path planning for two-dimensional planar motion, the omni-directional mobile robot using distance sensors was able to directly follow target positions with the simple proposed position feedback algorithm.

직류 및 고주파 마그네트론 스퍼터링법으로 증착한 Ti-Al-V-N 박막의 특성 (Characterizations of Ti-Al-V-N Films Deposited by DC and RF Reactive Magnetron Sputtering)

  • 손용운;정인화;이영기
    • 열처리공학회지
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    • 제13권6호
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    • pp.398-404
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    • 2000
  • The Ti-Al-V-N films have been deposited on various substrates by d.c and r.f reactive magnetron sputtering from a Ti-6Al-4V alloy target in mixed $Ar-N_2$ discharges. The films were investigated by means of XRD, AES, SEM/EDX, microhardness, TG and scratch test. The XRD and SEM results indicated that the films were of single B1 NaCl phase having dense columnar structure with the (111) preferred orientation. The composition of Ti-Al-V-N film was the Ti-7.1Al-4.3V-N(wt%) films. Adhesion and microhardness of Ti-Al-V-N films deposited by r.f magnetron sputtering method were better than those deposited by d.c magnetron sputtering method. The anti-oxidation properties of Ti-Al-V-N films were also superior to that of Ti-N film deposited by the same deposition conditions.

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A Feature of Stellar Density Distribution within Tidal Radius of Globular Cluster NGC 6626 in the Bulge Direction

  • Chun, Sang-Hyun;Lim, Dong-Wook;Kim, Myo-Jin;Sohn, Young-Jong
    • 천문학회보
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    • 제35권2호
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    • pp.82.1-82.1
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    • 2010
  • We have investigated the spatial configuration of stars within the tidal radius of metal poor globular cluster NGC 6626 in the bulge direction. Data were obtained in near-IR J,H,Ks bands with wide-field ($20'\times20'$) detector, WIRCam at CFHT. To trace the stellar density around target cluster, we sorted cluster's member stars by using a mask filtering algorithm and weighting the stars on the color-magnitude diagram. From the weighted surface density map, we found that the stellar spatial distributions within the tidal radius appear asymmetric and distorted features. Especially, we found that more prominent over-density features are extending toward the direction of Galactic plane rather than toward the directions of the Galactic center and its orbital motion. This orientation of the stellar density distribution can be interpreted with result of disk-shock effect of the Galaxy that the cluster had been experienced. Indeed, this over-density feature are well represented in the radial surface density profile for different angular sections. As one of the metal poor globular clusters with extended horizontal branch (EHB) in the bulge direction, NGC 6626 is kinematically decoupled from the normal clusters and known to have disk motion of peculiar motion. Thus, our result will be able to add further constraints to understand the origin of this cluster and the formation of bulge region in early universe.

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Si-ZnO n-n 이종접합의 구조 및 전기적 특성 (The Structure and Electrical Properties of Si-ZnO n-n Heterojunctions)

  • 이춘호;박순자
    • 한국세라믹학회지
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    • 제23권1호
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    • pp.44-50
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    • 1986
  • Si-ZnO n-n heterojunction diodes were prespared by r.f diode sputtering of the sintered ZnO target on n-type Si single crystal wafers and their structures and electrical properties were studied. The films were grown orientedly with the c-axis of crystallites perpendicular to the substrate surface at low r.f. powder and grown to polycrystalline films with random orientation at high r. f. powder. The crystallite size increased with the increasing substrate temperture The oriented texture films only were used to prepare the photovoltaic diodes and these didoes showed the photovoltaic effect veing positive of the ZnO side for the photons in the wavelength range of 380-1450nm. The sign reversal of phootovoltage which is the property os isotype heterojunction was not observed because of the degeneration of the ZnO films. The diode showed the forward rectification when it was biased with the ZnO side positive. The current-voltage characteristics exhibited the thermal-current type relationship J∝exp(qV/nkT) with n=1.23 at the low forward bias voltage and the tunnelling-current type relationship J∝exp($\alpha$V) where $\alpha$ was constant independent of temperature at the high forward bias voltage. The crystallite size of ZnO films were influenced largely on the photovoltaic properties of diodes ; The diodes with the films of the larger crystallites showed the poor photovoltaic properties. This reason may be cosidered that the ZnO films with the large crystallites could not grow to the electrically continuous films because the thickness of films was so thin in this experiment.

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La 첨가량에 따른 $Bi_{4-x}La_{x}Ti_{3}O_{12}$ 강유전체의 주파수특성 (The Ferroelectric Frequency characteristics of $Bi_{4-x}La_{x}Ti_{3}O_{12}$ ceramics with the variation of Lanthanum additives)

  • 김응권;박복기;박기엽;박춘배
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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    • pp.463-466
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    • 2001
  • In recent year, Ferroelectric $BLT(Bi_{4-x}La_{x}Ti_{3}O_{12})$ is a promising candidate materials. This study was practiced to make good conditions of BL T targets. In this study, calcination and sintering temperature were kept at $750^{\circ}C$, $1100^{\circ}C$ for 2 hour respectively. the density obtained 7.612, 7.98, $7.877g/cm^{3}$ as $La_{2}O_{3}$ contents were 0.0mol%, 0.25mol%, 0.5mol%. Especially, the lanthanum content of 0.5 mol% measured C-axis (117) preferred orientation more than the others targets in the XRD. In $\varepsilon_{r}-f$ relationship using by HP 4194 A impedance analyzer, the 0.5 mol% observed above 200 relative dielectric constant. but the dissipation factor was higher than others targets at 100Hz~13MHz range. SEM photograph with the content of $La_{2}O_{3}$ was observed like rod and plate types.

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유리기판위에 증착한 50% Pb-excess PZT박막의 전기적특성 (Electrical Properties of 50% Pb-excess PZT Thin Films Deposited on the Glass Substrates)

  • 정규원;박영;주필연;박기엽;송준태
    • 한국전기전자재료학회논문지
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    • 제14권5호
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    • pp.370-375
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    • 2001
  • PZT thin films (3500${\AA}$) ahve been prepared onto Pt/Ti/corning glass (1737) substrates with a RF magnetron sputtering system using Pb$\sub$1.50/(Zr$\sub$0.52/,Ti$\sub$0.48)O$_3$ ceramic target. We used two-step annealing techniques, PZT thin films were grown at a 300$^{\circ}C$ substrate temperature and then subjected to an RTA treatment. In case of 500$^{\circ}C$ RTA temperature show pyrochlore phase. The formation of Perovskite phase started above 600$^{\circ}C$ and PZT thin films generated (101) preferred orientation. As the RTA time and temperature increased, crystallization of PZT films were enhanced. The PZT capacitors fabricated at 650$^{\circ}C$ for 10 minutes RTA treatment showed remanent polarization 30 ${\mu}$C/$\textrm{cm}^2$, saturation polarization 42${\mu}$C/$\textrm{cm}^2$, coercive field 110kV/cm, leakage current density 2.83x10$\^$-7/A/$\textrm{cm}^2$, remanent polarization were decreased by 30% after 10$\^$9/ cycles.

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엘리트 유전 알고리즘을 이용한 비젼 기반 로봇의 위치 제어 (Vision Based Position Control of a Robot Manipulator Using an Elitist Genetic Algorithm)

  • 박광호;김동준;기석호;기창두
    • 한국정밀공학회지
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    • 제19권1호
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    • pp.119-126
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    • 2002
  • In this paper, we present a new approach based on an elitist genetic algorithm for the task of aligning the position of a robot gripper using CCD cameras. The vision-based control scheme for the task of aligning the gripper with the desired position is implemented by image information. The relationship between the camera space location and the robot joint coordinates is estimated using a camera-space parameter modal that generalizes known manipulator kinematics to accommodate unknown relative camera position and orientation. To find the joint angles of a robot manipulator for reaching the target position in the image space, we apply an elitist genetic algorithm instead of a nonlinear least square error method. Since GA employs parallel search, it has good performance in solving optimization problems. In order to improve convergence speed, the real coding method and geometry constraint conditions are used. Experiments are carried out to exhibit the effectiveness of vision-based control using an elitist genetic algorithm with a real coding method.

Molecular characterization of a repetitive element of Xanthomonas oryzae pv. oryzae

  • Yun, Choong-Hyo
    • 한국식물병리학회:학술대회논문집
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    • 한국식물병리학회 1995년도 Proceedings of special lectures on Molecular Biological Approaches to Plant Disease National Agricultural Science and Technology Institute Suwon, Korea
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    • pp.1-19
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    • 1995
  • The plasmid pJEL 101 contains a highly repetitive element from the genome of Xanthomonas oryae pv. oryzae that has properties of an insertional element. The insertional nature of the element, hereto referred to as IS203, was confirmed by molecular analyses of the element and three related elements that were isolated from X. oryzae. The related sequences were isolated on the basis of transposition to the transposon-trapping vector pL3SAC and hybridization with pJEL101. The trapped elements (IS203a, IS203b, and IS203c) were each composed of 1,055 base pairs with 25 base terminal inverted repeats. The elements caused a three base pair target site duplication at the site of insertion in the sacRB gene. The sequence of pJEL 101 has 96% base pair identity with IS203a and 99% identity with IS203a and IS203c but lacks three nucleotides of the consensus left terminal repeat. IS203b has the same DNA sequences as IS203c but is inserted ito the sacRB gene in the opposite orientation. The longest open reading frame of IS203a could code for a protein of 318 amino acids and molecular weight of 37, 151. A search of the Genbank database revealed that IS203 has 51% identity with 909 nucleotides of IS4551 from Escherichia coli. The predicted protein of ORF1 has 40% and 30% amino acid identity to the ORF1 of Tn4551 and the transposase of IS30, respectively.

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어패럴 산업(産業)의 브랜드 개발(開發)에 관(關)한 사례연구(事例硏究) - 일본(日本) 어패럴 기업(企業)을 중심(中心)으로 - (A Study on the Cases of the R & D of the Apparel industry - Focus on Brand Developments in the Japanese Apparel Corporation -)

  • 신재용;전태유
    • 패션비즈니스
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    • 제6권5호
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    • pp.112-124
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    • 2002
  • Japanese apparel industries have deployed the activities of plannings, production & sellings by brand marketings. Owing to it, they satisfied customers and accomplished the goal of corporation objective market advantage. All through this process it is very essential to establish the concept of product Through the analysis of the brand development in Japanese total apparel corporation; 1) it accesses synthetically to acquire sales and target benefit by active marketing based on the analysis of market environment; 2) on relation with customer, it comes close to customer in the process of buying and consuming product and provides a customer satisfaction in the process of those. All the way of the process above and the precedent, it is to complete the goal of corporation. The development of the brand in Japanese apparel corporation depends on the corporate's customeroriented marketing. Due to it, Japanese apparel corporation perceives the differentiation that the consuming pattern of customer is its life style so that Japanese apparel corporation provides the product that can satisfy customer needs.

셀렌화 공정을 제외한 RF 마그네트론 스퍼터링으로 제작된 Cu(In,Ga)Se2 박막의 구조 및 전기적 특성 (Structural and Electrical Properties of Cu(In,Ga)Se2 Thin Films Prepared by RF Magnetron Sputtering without Selenization)

  • 최정규;황동현;손영국
    • 한국표면공학회지
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    • 제46권2호
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    • pp.75-79
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    • 2013
  • A one-step route was developed to fabricate $Cu(In,Ga)Se_2$ (CIGS) thin films by radio frequency (RF) magnetron sputtering from a single quaternary $CuIn_{0.75}Ga_{0.25}Se_2$ target. The effects of the substrate temperatures on the structural and electrical properties of the CIGS layers were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and Hall effect measurements. All the deposited films showed a preferential orientation along the (112) direction. The films deposited at $300^{\circ}C$ and $400^{\circ}C$ revealed that chalcopyrite main (112) peak and weak prominent peaks of (220)/(204) and (312)/(116), indicating polycrystalline structures. The element ratio of the deposited film at $300^{\circ}C$ were almost the same as the near-optimum value. The carrier concentration of the films decreased with increasing substrate temperatures.