• Title/Summary/Keyword: Roll data

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Effect of Ground Roll Suppression Based on Karhunen-Loeve Transform (카루넨-루베 변환을 이용한 탄성파 그라운드 롤 억제 효과)

  • Jang, Seonghyung;Lee, Donghoon
    • Geophysics and Geophysical Exploration
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    • v.22 no.4
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    • pp.177-185
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    • 2019
  • Ground roll is a surface wave which is usually observed in the land seismic data. It is one of the typical coherent noise. During the reflection data processing, ground roll is removed because it is considered as noise. This removal process often causes the loss of reflection signals if the ground roll overlaps reflection signals. In this study, we look over Karhunen-Loeve Transform (KLT) and analyze its effects to suppress the ground roll appropriately while reducing the reflection loss. Numerical tests in homogeneous elastic media show that the ground roll has been properly rejected. However, the field data application reveals that there is no significant suppression of ground roll when compared to band-pass filtering. This can be considered that it is hard to calculate horizontally aligned gathers in the field data because the ground roll contains a wide range of frequency bands. On the contrary, the result of singular value decomposition (SVD) filtering shows that the ground roll has been significantly reduced. It is thought that the SVD filtering performs better in the ground roll suppression than KLT because it is easy to calculate the horizontally aligned gathers in the SVD filtering.

A STUDY ON THE ROLL-ALONG TECHNIQUE USED IN 2D ELECTRICAL RESISTIVITY SURVEYS (2차원 전기비저항 탐사에 사용되는 ROLL-ALONG 기법에 대한 고찰)

  • WonSeokHan;JongRyeolYoon
    • Journal of the Korean Geophysical Society
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    • v.6 no.3
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    • pp.155-164
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    • 2003
  • The validity and efficiency of the roll-along technique widely used in 2-D electrical resistivity survey are analyzed in case of the dipole-dipole and the Wenner-Schlumberger arrays by numerical modelling. The shallow anomalous resistivity bodies are successfully inverted both in the dipole-dipole and in the Wenner-Schlumberger arrays because the shallow data of pseudosection are not omitted by the roll-along technique. However, the deep anomalous resistivity bodies can not be well resolved due to the skip of observed data which is more significant in the Wenner-Schlumberger array having relatively poor horizontal coverage of obtaining data. Carrying out electrical survey adopting the dipole-dipole array, the skip of data is insignificant because it is unfeasible to expand the electrodes to the maximum electrode separation coefficient($n_max$) owing to low S/N ratio. In case of the Wenner-Schlumberger array, however, because it is generally feasible to expand the electrodes $n_max$ to the owing to high S/N ratio, it is highly possible that skip of data from the roll-along technique causes significant distortion of inversion results. Therefore, adopting the Wenner-Schlumberger array having deeper median depth(Edwards, 1977) than do the dipole-dipole array on condition of the same unit electrode spacing( ($a$) ) and $n_max$, it is recommended to determine $a$ based on not $n_max$but $n_prob$free from the skip of observing data and forward electrodes with keeping overlap interval 3/4 of the survey line length in order to reduce the distortion of resistivity structure and perform resistivity survey efficiently. These results are confirmed by numerical modelling.

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A Study on the EDT Characteristics of TM Work Roll and Variation of Strip Surface Roughness

  • Kim, Soon-Kyung;Moon-Kyung, Kim
    • KSTLE International Journal
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    • v.2 no.2
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    • pp.133-137
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    • 2001
  • This paper investigates the correlation between strip surface roughness and the surface of the work roll. As the actual temper mill(TM) is used, this data will be adopted to another actual temper mill for the application and operation of this experiment. Conclusions are as follows: Electro-discharge texturing(EDT) roll has homogeneous roughness distribution and shape, and also a sinuous peak surface and the life is 2 times longer than that of shot blast texturing(SBT) method. And the higher surface roughness of work roll, the more time is necessary at the EDT method. In the SBT method without the correlation of roughness, but impeller rotation speed with an uncontrollable peak count. The roughness of SBT roll is irregularity compared to that of EDT roll because the work roll roughness is transferred to the strip which was temper rolled, and produces a more desirable image and greater clarity to the color painted steel sheet.

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Fault Diagnosis of Roll Shape Under the Speed Variation in Hot Rolling Mill

  • Lee, Chang-Woo;Kang, Hyun-Kyoo;Shin, Kee-Hyun
    • Journal of Mechanical Science and Technology
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    • v.20 no.9
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    • pp.1410-1417
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    • 2006
  • The metal processing system usually consists of various components such like motors, work rolls, backup rolls, idle rolls, sensors, etc. Even a simple fault in a single component in the system may cause a serious damage on the final product. It is therefore necessary to diagnose the faults of the components to detect and prevent system failure. Especially, the defects in a work roll are critical to the quality of strip. It is especially difficult to detect faults of a roll by using the existing frequency analysis method if the speed of the roll is changing. In this study, a new diagnosis method for roll eccentricity under the roll speed changes was developed. The new method was induced from analyzing the rolling mechanism by using rolling force models, radius-speed relationship, and measured rolling force, etc. Simulation results by using the field data show that the proposed method is very useful.

Estimation of Roll Related Coefficients of a Ship by Using the System Identification Method (시스템 식별법을 이용한 선박의 횡동요 계수 추정)

  • 윤현규;손남선
    • Journal of the Society of Naval Architects of Korea
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    • v.41 no.4
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    • pp.53-58
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    • 2004
  • When a fast container ship or a naval vessel is turning, comparable roll motions occur. Therefore, roll effect has to be considered in the horizontal equations of motion of the ship to predict the maneuverability well. In this thesis, a new method to determine a roll model structure and estimate its coefficients by applying the system identification technique to the data of sea trial tests was proposed. The simulation results from the estimated roll model were well consistent with the true one in spite of the difference between the estimated and the true model structures of roll hydrodynamic moment.

Investigation on the Shoulder Shapes between Korean and American Women Age over 55 for Apparel (장·노년층 여성의 의복제작을 위한 어깨형태 연구 - 한국인과 미국인의 비교 -)

  • Choi, Mee-Sung
    • Fashion & Textile Research Journal
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    • v.5 no.3
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    • pp.260-266
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    • 2003
  • The objective of this study is to compare the general body measurements and shoulder shapes of Korean and American elderly women to supply basic data for the apparel design. The anthropometrics data was collected including both direct and indirect measurements of 283 women over the age of 55 in Korean and the American women. The statistical methods used for the analysis of measurement data are the T-test, Exploratory data analysis, ANOVA and Duncan-test respectively. The results of the T-test indicated that there is a significant difference in the 14 body measurement items except of waist circumference. The results of exploratory data analysis, an independent relationship between shoulder slope angle and forward shoulder roll of Korean women. On the other hand, there is a dependent relationship that the bigger shoulder slope and forward shoulder roll with wide cross back shoulder of American women. Comparison of mean among the three different age groups, aged 55~59 group shows significant differences in the value of difference between cross back shoulders and horizontal shoulder width. This finding indicates that the wide and forward roll shoulder needs to special pattern making like ease amount and curvature for fit and comfort for women's apparel.

Evaluation of Spray Flight Attitude for Agricultural Roll-balanced Helicopter using Kalman Filter (칼만필터를 이용한 농용 균평헬리콥터의 살포비행자세 평가)

  • Park, Hee Jin;Koo, Young Mo
    • Journal of Biosystems Engineering
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    • v.37 no.6
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    • pp.342-351
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    • 2012
  • Purpose: Aerial spraying with an agricultural unmanned helicopter became a new paradigm in the agricultural practice. Laterally tilting behavior of a conventional agricultural helicopter, resulting in the biased down-wash and uneven spray deposit is a physically intrinsic phenomenon while hovering and cruise flights. Authors studied and developed a roll-balanced agricultural helicopter with a raised pylon tail rotor system. In this study, the attitude of the roll-balanced helicopter was determined using the Kalman filter algorithm, and the quality of roll balancing of a bare-airframe helicopter was evaluated. Methods: Instantaneous attitudes were estimated using the advantage of gyroscope, followed by the long term correction and prediction using accelerometer data for the advantage of convergence. The attitudes of the fuselage were calculated by applying the Kalman filter algorithm. The spraying maneuver of the helicopter was performed at a field of 50 m long, and the attitude data were acquired and evaluated. Results: The determination of attitude using the inertial measurement unit(IMU) and Kalman filter was reliable and practical. The intrinsic attitude of the developed helicopter was stable and roll-balanced. The deviation of roll angle was ${\pm}6.3^{\circ}$ with an average of $0^{\circ}$, referring to roll-balanced. Conclusions: Handling quality of the roll attitude determined to be steadily balanced. The balancing behavior of the developed helicopter would result in an even spray pattern during aerial application.

A Study on the Prediction of Ship's Roll Motion using Machine Learning-Based Surrogate Model (기계학습기반의 근사모델을 이용한 선박 횡동요 운동특성 예측에 관한 연구)

  • Kim, Young-Rong;Park, Jun-Bum;Moon, Serng-Bae
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2018.05a
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    • pp.41-42
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    • 2018
  • This study is about the prediction of ship's roll motion characteristic which has been used for evaluating ship's seakeeping performance. In order to obtain the ship's roll RAO during voyage, this paper utilized machine learning-based surrogate model. By comparing the prediction result data of surrogate model with test data, we suggest the best approximation technique and data sampling interval of the surrogate model appropriate for predicting the ships' roll motion characteristic.

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A Study on the Roll Damping of Two-Dimensional Cylinders (2차원 주상체의 횡요감쇠에 대한 연구)

  • Yuck Rae H.;Lee Dong H.;Choi Hang S.;Jin Young M.;Bang Chang S.
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.197-200
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    • 2002
  • In this paper, roll damping coefficients for a non-conventional cross section, which is herein named as 'step' model, are investigated numerically and experimentally. Experiments are extensively carried out to estimate the roll damping coefficients. Numerical estimations are also made with the help of numerical codes. For convenience, the roll damping is divided into wave-making component and viscous component. The wave-making component is determined using a potential code and the viscous component using a viscous flow code, in which the fluid domain is taken as unbounded. In order to validate the present approach, a typical cross section with bilge is considered and our results are compared with published data. The comparison shows a good agreement qualitatively. For the step model, numerical results are compared well with experimental data besides some quantitative discrepancies at a certain range of frequency. It is thought that the discrepancy might be caused by the ignorance of the free surface in viscous computations. It is found in the case of the step model that not only the viscous component but also the wave component increases considerably compared to the section with bilge.

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Roll Motion Analysis of a 3 D.O.F. Planar Car Model using Instantaneous Centers (순간중심을 이용한 평면 3 자유도 자동차 모델의 롤 운동 해석)

  • Lee, Jae-Kil;Shim, Jae-Kyung
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.4
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    • pp.92-98
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    • 2006
  • In this paper, a planar car model with 3 degrees of freedom was analyzed using the concept of the roll center. To avoid ambiguity, force components which require experimental data were excluded. Only kinematic approach was used to find the position and orientation of the vehicle body and the position of the roll center. The roll center was found by the pole with infinitesimal movement and Kennedy-Aronhold theorem. Centrodes, which are the loci of instantaneous centers of planar motion, were constructed with analyzed results to show characteristics of vehicle body motion. To verify the presented analysis method in this paper, the locus of the roll center and the motion of a 3 D.O.F. planar car model were compared with those of the 1 D.O.F. model.