• 제목/요약/키워드: 시험경로

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Design a Path Following Line-of-Sight Guidance Law based on Vehicle Kinematics (비행체 운동 역학 기반 경로 추종 시선각 유도 법칙 설계)

  • You, Dong-Il;Shim, Hyun-Chul
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.40 no.6
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    • pp.506-514
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    • 2012
  • This paper represents a method for designing of path following Line-of-Sight(LOS) guidance law based on vehicle kinematics. In general, a LOS guidance law which is composed of gains and approach length as design parameters is designed by empirical or trial-and-error method. These approaches cannot guarantee a precision tracking performance of guidance law consistently. Also, the design parameters should be redesigned with variations of vehicle maneuverability and flight velocity. Based on a vehicle kinematics with its velocity, the proposed method for designing of parameters not only minimizes the number of design parameters, also has a reliable and consistent tracking performance using variable guidance gain changed in accordance with flight velocity. This is validated by nonlinear simulation with $1^{st}$ order attitude response dynamics and flight experiments with given linear and circular path.

A Study on the Path Loss of Underwater Acoustic Channel Based on At-sea Experiment at the South Sea of Korea (남해 실해역 시험 기반 수중음향채널 경로손실에 관한 연구)

  • Kim, Min-Sang;Lee, Tae-Seok;Cho, Yong-Ho;Im, Tae-Ho;Ko, Hak-Lim
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.3
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    • pp.405-411
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    • 2020
  • Recently, studies on underwater communication, related to the development of underwater resources, disaster monitoring and defense, have been actively carried out. In the design of wireless communication systems, path loss is the most important information to derive a link budget that is required to guarantee communication reliability by calculating received power level for the given communication link. The underwater acoustic channel have different characteristics according to geographical location and relevant environmental factors such as water temperature, depth, wave height, algae, and turbidity. Subsequently, many research institutes aiming to develop underwater acoustic communication systems are researching actively on the underwater acoustic channels in various sea areas. In Korea, however, studies on the path loss of the acoustic channel are still insufficient. Therefore, in this study, the path loss of the acoustic channel are studied based on measurement data of the at-sea experiment conducted at Geohae-do, southern sea of Korea.

Refinement of Interpretation Method for Reliable Vs Profiling in Downhole Seismic Method (다운홀 시험에서 신뢰성 있는 전단파 속도 주상도 도출을 위한 해석 기법의 개선)

  • Bang, Eun-Seok;Kim, Dong-Soo;Yoon, Jong-Ku
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3C
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    • pp.157-170
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    • 2006
  • Downhole method is considered as giving a little unreliable Vs profile when the signal to noise ratio(S/N) is low and the travel time information is erroneous although it is economical and ease of operation. Direct method has been applied for obtaining adequate result in this case. But it is difficult to determine optimum result by using direct method which is subjective and considering straight ray path. Therefore, in this paper, Mean Refracted Ray Path Method(MRM) was proposed, which is automated and considering refracted ray path. Artificial travel time data adding some travel time error was generated by forward modeling based on Snell's Law and travel time data was also obtained from numerical signal traces using FEM modelling. Using these travel time data, reliability of MRM was verified in the manner of comparing the results determined by MRM with the model. Finally, proposed method was applied to the real field data and it was considered as improved method for obtaining the optimum result in downhole seismic method.

Shearing Behaviors of the Soft Marine Clay in Undrained and Drained Conditions (연약해성점토의 비배수 및 배수 전단 거동)

  • 이영휘;김용준;정강복
    • Journal of the Korean Geotechnical Society
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    • v.17 no.5
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    • pp.29-36
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    • 2001
  • 한반도 남해안의 광양만에서 채취한 연약 해성점토의 물리적 및 역학적 특성을 조사하기 위한 일련의 실내시험을 수행하였다. 물리적 성질 및 압밀시험 결과의 분석에 따르면, 시험에 사용된 시료는 정규압밀점토로 나타났다. 압밀비배수 삼축시험 결과로부터 새로운 간극수압계수(C)를 제안하였고, 이 계수는 유효응력경로를 예측하기 위한 방정식에 적용되었다. 또한, 비배수조건에서 전단변형률은 오로지 응력비만의 함수라는 사실이 실험결과로부터 밝혀졌다. 따라서 비배수 조건에서의 전단변형률 계산식이 제안되었으며, 이들 관계식을 이용하여 비배수(CIU) 및 배수조건(CID)에서의 점토의 거동을 예측하기 위한 새로운 구성방정식이 제안되었다. 이 구성방정식은 Roscoe와 Poorooshasb이 제안한 증분응력-변형률 이론을 기초로 하였으며, 제안된 구성방정식을 적용하여 예측한 배수전단특성을 실측된 결과에 매우 근접하는 경향을 나타내었다.

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Design of RF Supporting Unit for COMS RF Compatibility Test (COMS RF호환성 시험을 위한 RF지원 장비의 설계 및 제작)

  • Park, Durk-Jong;Park, Chun-Woo;Ahn, Sang-Il
    • Aerospace Engineering and Technology
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    • v.7 no.2
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    • pp.176-186
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    • 2008
  • As determined single coaxial cable for the interface between satellite and ground station in COMS RF compatibility test, RF supporting unit was required to allow signals in different frequency-band to be exchanged in the single coaxial cable. In addition, the path loss between satellite and ground station in normal operation should be simulated through two RF supporting units connected to the ends of single coaxial cable. As an effort to design RF supporting unit, level diagram was firstly conducted on the basis of measured data for each element. From the level diagram, it was found that single coaxial cable connected with two RF supporting units properly represented the path loss between satellite and ground station After RF supporting unit was integrated on aluminum plate, it was tested that input signal level at each test cap linked with MODCS and TC&R was tunable within the required dynamic range. RF supporting unit, now completely integrated, will be applied in the upcoming COMS RF compatibility test.

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Behavior of K0-Consolidated Clay in Torsion Shear Tests (비틀림 전단시험(剪斷試驗)에 의한 K0-압밀점토(壓密粘土)의 거동(擧動))

  • Hong, Won Pyo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.8 no.1
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    • pp.151-157
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    • 1988
  • A series of torsion shear tests were performed according to various stress-paths on hollow cylinder specimens of $K_0$-consolidated clay to investigate the influence of rotation of the principal stresses on the stress-strain and strength characteristics. The effects of stress-paths and reorientation of principal stress were mainly observed in the prefailure stress-strain behavior. The experimentally obtained failure surface from torsion shear tests could practically be modeled by an isotropic failure criterion. Coupling effects between stresses and strains were investigated when both torsion shear and vertical stresses were applied. The work-space in torsion shear tests was illustrated and the relation between stresses and strain increments was also investigated in the work-space.

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Implementation and field test for autonomous navigation of manta UUV (만타형 무인 잠수정의 개발과 실해역 성능시험)

  • Ko, Sung-Hyub;Kim, Dong-Hee;Kim, Joon-Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.6
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    • pp.644-652
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    • 2013
  • This paper describes the development and field experiments of Manta-type Unmanned Underwater Vehicle (UUV). Various simulations for Manta UUV are performed by using the nonlinear 6-DOF motion of equations. Through this simulation we verified the motion performances of Manta UUV. To acquire the blueprint of Manta UUV, it was designed with the simulation results. The Manta UUV uses a Doppler Velocity Log (DVL), gyrocompass, GPS, pressure sensor and other minor sensors, applied to measure the motion, position and path of Manta UUV. For its propulsion and changing a direction in the underwater, one vertical fin and four horizontal fins are installed at the hull of UUV. The Manta UUV system was verified with motion and autonomous navigation test at field.

Stress Path Dependent Deformation Characteristics of A Normally Consolidated Saturated Cohesive Soil (정규압밀 포화점성토의 응력경로에 따른 변형특성)

  • 권오엽;정인준
    • Geotechnical Engineering
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    • v.5 no.2
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    • pp.45-56
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    • 1989
  • The influence of stress path on the deformation characteristics of clay has been studied through a series of stress-path controlled triaxial tests on artificially sedimented and normally con- solidated Kaolinite. It has been found that there exists a critical stress increment ratio, Kc, in which stress·strain characteristics possesses a linear relationships and beyond Kc, strain hardening. A modified hyperbolic constitutive model for the strain hardening behavior has been formulated based on the Drnevich's hyperbolic function. And, a method of settlement analyses has been Proposed wherein the effect of stress path during consolidation is taken into account.

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Clustering of Time-Course Microarray Data Using Pharmacokinetic Parameter (약동학적 파라미터를 이용한 시간경로 마이크로어레이 자료의 군집분석)

  • Lee, Hyo-Jung;Kim, Peol-A;Park, Mi-Ra
    • The Korean Journal of Applied Statistics
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    • v.24 no.4
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    • pp.623-631
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    • 2011
  • A major goal of time-course microarray data analysis is the detection of groups of genes that manifest similar expression patterns over time. The corresponding numerous cluster algorithms for clustering time-course microarray data have been developed. In this study, we proposed a clustering method based on the primary pharmacokinetic parameters in the pharmacokinetics study for assessment of pharmaceutical equivalents between two drug products. A real data and a simulation data was used to demonstrate the usefulness of the proposed method.

Traffic Load-aware Reactive Routing Scheme in Wireless Mobile Ad hoc Network (무선 이동 애드 혹 네트워크에서 트래픽 부하를 고려한 리액티브 라우팅 기술)

  • Ko, Sung-Won
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.6
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    • pp.109-116
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    • 2007
  • The lack of load-balancing functionality in most existing ad hoc routing protocols often causes congestion resulting in bad performance and short lifetime of participating nodes. We present an auxiliary scheme for reactive routing protocols to discover an unloaded route, thereby decreasing possibility of congestion. The scheme allows an intermediate node to determine whether to be a relaying node for a newly constructed route autonomously based on the occupancy of its queue. Thus the scheme does not require network-wide load information. Simulation results show that the proposed scheme distributes traffic load well.