• Title/Summary/Keyword: survey and estimation errors

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Self-Tuning Position Control of a Remotely Operated Vehicle (원격무인 잠수정의 자기동조 위치제어)

  • Lee, Pan-Muk
    • Journal of Ocean Engineering and Technology
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    • v.3 no.2
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    • pp.551-551
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    • 1989
  • In general, a remotely operated vehicle(ROV) operates at deep sea. The control system of ROV is composed of two local loops; the first loop placed on the surface vessel monitors and manipulates the attitude of the ROV using joystick, and the second part on the ROV automatically controls thrusters and acquires positional data. This paper presents a position control simulation of a ROV using an adaptive controller and discusses the control effects of two different conditions. The design of an adaptive control system is obtained by the application of a self-tuning controller with the minimization of an appropriate cost function. The parameters of the control system are estimated by a recursive least square method(RLS). In the simulation, a Runge-Kutta method is used for the numerical integration and the generated outputs are obtained by adding measurement errors. Additionally, this paper discusses the mathematical modelling of a ROV and make a survey of control systems.

Self-Tuning Position Control of a Remotely Operated Vehicle (원격무인 잠수정의 자기동조 위치제어)

  • Lee, Pan-Muk
    • Journal of Ocean Engineering and Technology
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    • v.3 no.2
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    • pp.51-58
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    • 1989
  • In general, a remotely operated vehicle(ROV) operates at deep sea. The control system of ROV is composed of two local loops; the first loop placed on the surface vessel monitors and manipulates the attitude of the ROV using joystick, and the second part on the ROV automatically controls thrusters and acquires positional data. This paper presents a position control simulation of a ROV using an adaptive controller and discusses the control effects of two different conditions. The design of an adaptive control system is obtained by the application of a self-tuning controller with the minimization of an appropriate cost function. The parameters of the control system are estimated by a recursive least square method(RLS). In the simulation, a Runge-Kutta method is used for the numerical integration and the generated outputs are obtained by adding measurement errors. Additionally, this paper discusses the mathematical modelling of a ROV and make a survey of control systems.

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Investigating delay factors in construction industry: A Korean perspective

  • Acharya, Nirmal Kumar;Im, Hae-Man;Lee, Young-Dai
    • Korean Journal of Construction Engineering and Management
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    • v.7 no.5
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    • pp.177-190
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    • 2006
  • Construction projects are facing delay problems. Delays in construction have been immense effect on performance or satisfactory delivery of the project. Delays have been causing project cost overrun as well as it is a source of dispute hence damaging the relationship between the project participants. The purpose of this study was to explore the causes of delay risk through a field survey study. Data were collected from construction professionals working in owner, consultant and contractor organizations. All together 208 questionnaire instruments were used and analyzed by employing statistical tools (SPSS computer program). 19 delay factors were identified by this study, out of which following factors were critical: Frequent interruptions from public (local people, pressure group etc.), changed site condition, failure to provide required construction site, unrealistic project time estimation and design errors.

Performance Assessment of Several Established Pitch Detection Algorithms in Voices of Benign Vocal Fold Lesions (양성후두 질환 음성에 대한 여러 기존 피치검출 알고리즘의 성능 평가)

  • Jang, Seung-Jin;Choi, Seong-Hee;Kim, Hyo-Min;Choi, Hong-Shik;Yoon, Young-Ro
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.407-408
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    • 2007
  • Robust pitch estimation is an important study in many areas of speech processing. In voice pathology, diverse statistics extracted form pitch were commonly used to test voice quality. In this study, we compared several established pitch detection algorithms (PDAs) for verification of adequacy of the PDAs. In the database of total pathological voices of 99 and normal voices of 30, an analysis of errors related with pitch detection was evaluated between pathological and normal voices, or among the types of pathological voices such as benign vocal fold lesions; polyp, nodule, and cysts. Consequently, it is required to survey the severity of tested voice in order to obtain accurate pitch estimates.

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Constraints on cosmology and baryonic feedback by the combined analysis of weak lensing and galaxy clustering with the Deep Lens Survey

  • Yoon, Mijin;Jee, M. James;Tyson, Tony
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.2
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    • pp.41.1-41.1
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    • 2018
  • We constrain cosmological parameters by combining three different power spectra measured from galaxy clustering, galaxy-galaxy lensing, and cosmic shear using the Deep Lens Survey (DLS). Two lens bins (centered at z~0.27 and 0.54) and two source bins (centered at z~0.64, and 1.1) containing more than one million galaxies are selected to measure the power spectra. We re-calibrate the initial photo-z estimation of the lens bins by matching with SHELS and PRIMUS and confirm its fidelity by measuring a cross-correlation between the bins. We also check the reliability of the lensing signals through the null tests, lens-source flipping and cross shear measurement. Residual systematic errors from photometric redshift and shear calibration uncertainties are marginalized over in the nested sampling during our parameter constraint process. For the flat LCDM model, we determine S_8=sigma_8(Omega_m/0.3)^0.5=0.832+-0.028, which is in great agreement with the Planck data. We also verify that the two independent constraints from the cosmic shear and the galaxy clustering+galaxy-galaxy lensing measurements are consistent with each other. To address baryonic feedback effects on small scales, we marginalize over a baryonic feedback parameter, which we are able to constrain with the DLS data alone and more tightly when combined with Planck data. The constrained value hints at the possibility that the AGN feedback in the current OWLS simulations might not be strong enough.

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Nonignorable Nonresponse Imputation and Rotation Group Bias Estimation on the Rotation Sample Survey (무시할 수 없는 무응답을 가지고 있는 교체표본조사에서의 무응답 대체와 교체그룹 편향 추정)

  • Choi, Bo-Seung;Kim, Dae-Young;Kim, Kee-Whan;Park, You-Sung
    • The Korean Journal of Applied Statistics
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    • v.21 no.3
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    • pp.361-375
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    • 2008
  • We propose proper methods to impute the item nonresponse in 4-8-4 rotation sample survey. We consider nonignorable nonresponse mechanism that can happen when survey deals with sensitive question (e.g. income, labor force). We utilize modeling imputation method based on Bayesian approach to avoid a boundary solution problem. We also estimate a interview time bias using imputed data and calculate cell expectation and marginal probability on fixed time after removing estimated bias. We compare the mean squared errors and bias between maximum likelihood method and Bayesian methods using simulation studies.

Sample Design in Korea Housing Survey (주거 실태 및 수요조사 표본설계)

  • Byun, Jong-Seok;Choi, Jae-Hyuk
    • Survey Research
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    • v.11 no.1
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    • pp.123-144
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    • 2010
  • In new sample design for Korea Housing Survey to research about housing policy, total strata are forty five because individual results of sixteen regions are estimated. The sample size is determined by sample errors of several variables which are the living area, family income, householder income, and living expenses. The sample size of each region is determined by relative standard error of existing result, and the strata sample size is to use the square root proportion allocation. Enumeration districts are sampled by the probability proportion to size systematic sampling in proportion to the enumeration district size, and the systemic sampling to use assortment characteristics. We considered a new apartment complex because of variation reflections which are rebuilder and redevelopment of houses. To get estimators of mean and variance, we used the design weighting, non-response adjusting, and post-stratification. In order to consider estimation efficiency, we calculate the design effect using estimators of variance.

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Solution Methods for OD Trip Estimation in Stochastic Assignment (확률적 통행배정하에서 기종점 통행량추정 모형의 개발)

  • Im, Yong-Taek
    • Journal of Korean Society of Transportation
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    • v.24 no.4 s.90
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    • pp.149-159
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    • 2006
  • Traditional trip tables are estimated through large-scale surveys such as household survey, roadside interviews, and license Plate matching. These methods are, however, expensive and time consuming. This paper presents two origin-destination (OD) trip matrix estimation methods from link traffic counts in stochastic assignment, which contains perceived errors of drivers for alternatives. The methods are formulated based on the relation between link flows and OD demands in logit formula. The first method can be expressed to minimize the difference between observed link flows and estimated flows, derived from traffic assignment and be solved by gradient method. The second method can be formulated based on dynamic process, which nay describe the daily movement patterns of drivers and be solved by a recursive equation. A numerical example is used for assessing the methods, and shows the performances and properties of the models.

Telephone Survey for Grasping Clinical Actual State of Bloodletting Therapeutics in Korea (국내 자락(사혈)요법 임상 실태 파악을 위한 전화조사)

  • Han, Chang-Hyun;Kim, Seon-Woong;Lee, Seung-Deok;Shin, Mi-Suk;Shin, Seon-Hwa;Choi, Sun-Mi
    • Journal of Acupuncture Research
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    • v.23 no.6
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    • pp.177-187
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    • 2006
  • Objectives : Bloodletting therapeutics is one of the most popular oriental treatments in Korea. In this study, we operate the Telephone Survey for grasping clinical actual state bloodletting therapeutics in Korea. Methods : The list of the Korean medical doctors with experiences more than 10 years is provided by the Association of the Korean Oriental Medicine. A stratified random sample of Korean medical doctors is drawn for the telephone interviews. We choose a bound on the error of estimation equal to 3.2 percentage, and the sample size is 321 for the national sample. We develop a questionnaire for telephone interviews. We carefully design the questionnaire to minimize non-sampling errors by using the focus group activities and the pretest. We give the details of the results based on the sample design. Also, we present some socialdemograhpic characteristics for the samples. Telephone interviews with them were conducted by the well-trained interviewers of College of Korean Medicine student from 11th May 2006 to 17th May 2006. Results : 1. Two hundred eighty eight(89.4%) out of 322 Korean oriental medical doctors used bloodletting therapeutics. 2. The most common main bloodletting treatment is reported by patients was musculo-skeletal disorder(60.2%). 3. Two hundred ninety one(90.3%) out of 322 Korean oriental medical doctors opposed that commercial using bloodletting without medical diagnosis. Conclusion : Bloodletting therapeutics is one of the most popular oriental treatments in Korea. The majority(89.4%) of Korean medical doctors used bloodletting therapeutics in this survey.

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Convergence of Initial Estimation Error in a Hybrid Underwater Navigation System with a Range Sonar (초음파 거리계를 갖는 수중복합항법시스템의 초기오차 수렴 특성)

  • LEE PAN MOOK;JUN BONG HUAN;KIM SEA MOON;CHOI HYUN TAEK;LEE CHONG MOO;KIM KI HUN
    • Journal of Ocean Engineering and Technology
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    • v.19 no.6 s.67
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    • pp.78-85
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    • 2005
  • Initial alignment and localization are important topics in inertial navigation systems, since misalignment and initial position error wholly propagate into the navigation systems and deteriorate the performance of the systems. This paper presents the error convergence characteristics of the hybrid navigation system for underwater vehicles initial position, which is based on an inertial measurement unit (IMU) accompanying a range sensor. This paper demonstrates the improvement on the navigational performance oj the hybrid system with the range information, especially focused on the convergence of the estimation of underwater vehicles initial position error. Simulations are performed with experimental data obtained from a rotating ann test with a fish model. The convergence speed and condition of the initial error removal for random initial position errors are examined with Monte Carlo simulation. In addition, numerical simulation is conducted with an AUV model in lawn-mowing survey mode to illustrate the error convergence of the hybrid navigation System for initial position error.