• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.746-751
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• 2003

A method of measuring the length of defects on the wall of the spent nuclear fuel pool using the image processing and a laser slit beam is proposed. Since the defect monitoring camera is suspended by a crane and hinged to the crane hook, the camera viewing direction can not be adjusted to the orientation that is exactly perpendicular to the wall. Thus, the image taken by the camera, which is horizontally rotated along the axis of the camera supporting beam, is distorted and thus, the precise length can not be measured. In this paper, by using the LASER slit beam generator, the horizontally rotated angle of the camera is estimated. Once the angle is obtained, the distorted image can be easily reconstructed to the image normal to the wall. The estimation algorithm adopts a 3-dimensional coordinate transformation of the image plane where both the laser slit beam and the original image of the defects exist. The estimation equation is obtained by using the information of the beam projected on the wall and the parameters of this equation are experimentally obtained. With this algorithm, the original image of the defect taken at arbitrary rotated angle can be reconstructed to an image normal to the wall. From the result of a series of experiments, the accuracy of the defect is measured within 0.6 and 1.3 % error bound of real defect size in the air and underwater, respectively under 30 degree of the inclined angle of the laser slit beam generator. Also, the error increases as the inclined angle increases upto 60 degree. Over this angle, the defect length can not be measured since the defect image disappears. The proposed algorithm enables the accurate measurement of the defect length only by using a single camera and a laser slit beam.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.160-167
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• 2020

A two-stroke diesel engine and a propeller normally adopted in large merchant ships are regarded as major ship vibration sources. They are directly connected and generate various excitation components proportional to the rotating speed of diesel engine. Among the components, the magnitude of two excitation components with the same frequency generated by both engine and propeller can be compensated by the adjustment of their phase difference. It can be done by the optimization of propeller assembly angle but requires a number of burdensome trials to find the optimal angle. In this paper, the efficient estimation method to determine optimal propeller assembly angle is proposed. Its application requires the axial vibration measurement in sea trial and the numerical vibration analysis for propulsion shafting which can be substituted by additional vibration measurement after one-trial modification of propeller assembly angle. In order to verify the validity of the proposed method, the phase difference between two fifth order excitation components generated by both diesel engine and propeller of a real ship is calculated by the finite element analysis and its result is indirectly validated by the comparison of axial vibration responses at intermediate shaft obtained by the numerical analysis and the measurement in sea trial. Finally, it is numerically confirmed that axial vibration response at intermediate shaft at a resonant speed can be decreased more than 87 % if the optimal propeller assembly angle determined by the proposed method is applied.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.79-87
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• 1990

An automatic guidance system based upon two position-measurement systems was designed to record where the tractor traveled and to guide the tractor along the predetermined path. An algorithm, using the kinematic behavior of tractor movement, was developed to determine the steering angle to reduce lateral position error. The algorithm was based upon constant travel speed, constant steering rate, and zero slip angles of the tractor wheels. The algorithm was evaluated through use of computer simulation and verified in field experiments. Results showed that the distance interval between position measurements was an important factor in guidance system performance. The position-measurement error of the guidance system must be less than 5 cm to be acceptably precise for field operations. An algorithm based upon a variable steering rate might improve the stability of the guidance system. More accurate measurement of tractor position and yaw angle, and faster error processing are required to improve the field performance of the guidance system.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.64-70
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• 2003

A measurement of spacecraft alignment is an important process of spacecraft assembly, integration and test because it is necessary that a ground station controls the precise positions of on-orbit spacecraft by using the alignment data of attitude orbit control sensors(AOCS) on spacecraft. In addition, accuracy of spacecraft alignment requirement is about $0.1^{\circ}$~$0.7^{\circ}$. The spacecraft alignment is measured by autocollimation of theodolite. This paper describes the measurement principle and method of spacecraft alignment. The result shows that all of the AOCS on the spacecraft are aligned within the tolerance required through the alignment measurement.

• Journal of the Ergonomics Society of Korea
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• v.20 no.3
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• pp.27-35
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• 2001

The measurement of the fermoral anteversion is an important factor in the practice of orthopedic surgery. The anteversion is measured by means of the axis of head and neck of the femur. In this study. widely used computed tomography method of measuring anteversion was tested on femoral necks of patients. Measurement by the manual method and image viewer of computed tomography to determine the anteversion of femoral head were carried out on both femurs. In January and February 2001, 30 patients 3 to 6 years of age were randomly selected from Seoul National University Hospital. the purpose of this paper was to introduce a new method to measure femoral anteversion angle utilizing image viewer program. This new method was more accurate and convenient than the conventional manual method. No significant difference was observed between the manual method and the image viewer measurement of femoral anteversion. In conclusion, image viewer program was statistically more reliable in determining the angle of the fermoral anteversion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.685-688
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• 2004

This paper addresses the study on developing the angular vibration calibration system which requires the highly accurate measurement technique of the amplitude and period of an oscillating angular motion. Two developed models for the low and high frequency ranges are introduced and their main features are also compared. In addition to the angular vibration exciters, a new measurement method, referred to the 'equi-angle sampling method', is proposed and its theoretical backgrounds are introduced. The proposed method is shown to provide much less measurement uncertainty, compared the fringe counting method. Experimental results demonstrate what amount of angular vibration amplitude measurement uncertainty is improved by suing the proposed equi-angle sampling method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.98-104
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• 2004

A spacecraft alignment measurement requires highly precise measurement accuracy which is less than ${\pm}0.5^{\circ}$. In general, such an alignment measurement has been performed by using three or more theodolites. However, it contains the latent accuracy error because of a position stability of spacecraft, etc. The new alignment measurement system which consists of a theodoilte, a rotating table and a digital inclinometer has been developed to possibly to possibly reduce the error. This paper describes the concept and methodology of methodology of measurement system. It was found that new measurement system can provide more accurate results than the conventional system.

• Physical Therapy Rehabilitation Science
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• v.5 no.1
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• pp.22-28
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• 2016

Objective: The Back Mapper is one type of Rasterstereography and it can be used in the clinic without radiation exposure. The purpose of our study was to prove the reliability and validity of the Back Mapper and to compare it with the Spinal Mouse, which is an assessment tool for spinal curvatures using a wheeled mouse, and the Cobb angle by X-ray. Design: Cross-sectional study. Methods: Twenty healthy adults participated in the test to investigate for the inter-rater reliability, intra-rater reliability, and concurrent validity. The tests were performed with assessment devices for scoliosis such as the Back Mapper, Spinal Mouse and Cobb's angle. Data was analyzed by an intraclass correlation coefficient (ICC) value and a standard error of measurement for reliability and correlation analysis for validity. Results: Intra-rater reliability of the Back Mapper was good (Cronbach's ${\alpha}$=0.821-0.984, ICC=0.696-0.969) except for assessing the lordotic angle. Inter-rater reliability was good (Cronbach's ${\alpha}$=0.870-0.958, ICC=0.770-0.919) in assessment for trunk imbalance, rotation of scapulae, thoracic angle, lumbar angle, and kyphotic angle. The kyphotic angle in the Spinal Mouse had a significant correlation icompared with the Back Mapper (r=0.510, p<0.05), and the Cobb's angle from an X-ray had a significant correlation with trunk inclination (r=0.532, p<0.05). Conclusions: These findings provide good intra-reliability of the Back Mapper in healthy subjects, but the Back Mapper requires more experienced practice to have good inter-reliability. Also, the variables of the Back Mapper does not seem as appropriate compared with the Cobb angle by X-ray.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.2
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• pp.29-34
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• 2015

PURPOSE: The purpose of present study was to introduces an exceptional case in measurement methods (CVA, CRA and Cobb angle) to identify the FHP with verified reliability and validity. Subjects: Three males aged 30 years were recruited: A Normal, B and C who have FHP. METHODS: All the subjects were measured CVA, CRA and Cobb angle with the Photogrammetry and Radiography. RESULTS: The results revealed that it is not enough for measurement methods to identify the FHP using CVA, CRA and Cobb angle. On Photogrammetry values; CVA had $65^{\circ}$, CRA was $148^{\circ}$ of Normal subject A and CVA had $61^{\circ}$, CRA was $149^{\circ}$ of FHP subject B and CVA had $51^{\circ}$, CRA was $149^{\circ}$ of FHP subject C. On Radiography values; CVA had $73^{\circ}$, CRA was $148^{\circ}$ and Cobb was $50^{\circ}$ of Normal subject A and CVA had $70^{\circ}$, CRA was $150^{\circ}$ and Cobb was $53^{\circ}$ of FHP subject B and CVA had $61^{\circ}$, CRA was $153^{\circ}$ and Cobb was $31^{\circ}$ of FHP subject C. CONCLUSION: The reliable CVA, CRA and Cobb angle use methods from the previous studies might not be suitable for the diagnose the FHP. We think that it is necessary to have more detailed evaluation methods and the radiography is also needed for clear evaluations because of some possible exceptions.

• The korean journal of orthodontics
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• v.35 no.4 s.111
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• pp.251-261
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• 2005

Enlargement is an inherent property of X-rays which occurs when straight hues diverse from small a focal spot. The purpose of the present study was to evaluate the validity of the correction of gonial angle width enlarged on frontal cephalogram, using frontal and lateral cephalograms taken orthogonally from each other. In 40 adult individuals, frontal and lateral cephalograms were taken at a $90^{\circ}$ angle using the Head Posture Aligner. The angle width was measured on the frontal cephalogram and subsequently. the corrected angle width was calculated using the magnification rate of two cephalograms. Measured and corrected angle widths were compared with the measurement from the 3D CT image. The measurement or the frontal cephalogram showed a 9.10mm of enlargement on average ranging from 7.92 to 11.31mm. Corrected angle width measurement showed a 0.14mm difference with the 3D CT image measurement, which was not statistically significant. The results of the study indicate that actual au91e width can be approached through calculation using frontal and lateral cephalograms taken orthogonally with the help of the Head Posture Aligner The study also showed that the magnitude of correction error did not show a significant correlation with the amount of menton deviation, and it suggests that the present correction method is valid even in individuals with severe facial asymmetry.