• 동력기계공학회지
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• 제17권5호
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• pp.121-127
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• 2013

In this paper, we propose a distance measurement system for automatic berthing control using a stereo camera mounted on a rotation control device, and a radial pattern target. Automatically controlling the position and attitude of a ship aims to prevent maritime accidents due to human error. Our goal is to measure the relative distance between a ship and an onshore or offshore target for berthing. Therefore, the distance should be continuously measured while tracking a fixed point on a target. To this end, we developed a stereo camerabased distance measurement system that satisfied these requirements. This paper describes the structure and principle of the measurement system. We validate the distance error for target incline due to the relative position and attitude between a camera and a target in miniature scale. In addition, the findings of an experiment in an outdoor environment demonstrate that the proposed measurement system has accuracy within 1 m at a range of 20-100 m which is the acceptable accuracy for automatic berthing.

• 동력기계공학회지
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• 제15권5호
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• pp.91-96
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• 2011

The handling ability of containers at the terminal strongly depends on the performance of the cargo handling system such as RTGC(Rubber Tired Gantry Crane) and RMGC(Rail Mounted Gantry Crane). This paper introduces a guide line measurement system on the operating condition, in which two camera are installed to detect the guide line. Because the line tracking is the basic technique for control system design of RTGC, it is necessary to develop a useful and reliable measurement system. If the displacement and angle of the RTGC relative to a guide line as the trajectory to follow is obtained, the position of RTGC is automatically calculated. Therefore, in this paper, a camera-based measurement system is introduced. The proposed measurement system is robust against light fluctuation and cracks of the guide line. This system consists of two camera and a PC which are installed at the lower side of the RTGC. Two edges of the guide line are detected from an input image taken by the cameras in the moving state, and these positions are determined in a Hough parameter space by using the Hough transformation method. From the experimental results, the accuracy and usefulness of the proposed system is evaluated by comparing other instruments.

• 한국해양공학회지
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• 제21권4호
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• pp.45-54
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• 2007

In the context of auto-landing containers from a container ship to a truck or automatic guided vehicle and vice versa, this research investigates three schemes, one in Part I and two in Part II, for measuring the absolute position of a container. Coordinate transformations between the reference-coordinate, sensor-coordinate, and body-coordinate systems are briefly discussed. The scheme explored in Part I aims the use of three laser-slit sensors, which are relatively inexpensive. In this case, nine nonlinear equations are formulated for six unknown variables (three for orientation and three for position), so a closed-form solution is not available. Instead, an approximate solution through linearization was derived. An advantage of the method in Part I is its ability to measure an absolute position in 3D space, while a disadvantage is the computation time required to obtain pseudo-inverses and the approximate nature of the obtained solution. Numerical examples are provided.

• 한국전자통신학회논문지
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• 제6권5호
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• pp.775-781
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• 2011

실내에서 이동로봇의 절대위치 측정을 위해서 초음파를 이용하는 초음파 위치측정 시스템이 많이 연구되고 있다. 이러한 초음파 위치측정 시스템들은 초음파의 혼신을 피하기 위해 순차 발신하는 방법을 사용하고 있다. 그러나 이러한 순차 발신으로 인해 이동로봇이 이동하는 경우에는 초음파의 수신위치가 변하므로 위치측정 정도가 떨어지게 된다. 본 논문에서는 수신시점에 따른 가중치를 적용하는 새로운 위치추정 알고리즘을 제안하였다. 그리고 제안된 알고리즘을 기존의 초음파위성시스템에 적용하여 개선된 초음파위성시스템을 구축하였다. 그리고 실험을 통하여 제안된 알고리즘을 가진 개선된 초음파위성시스템의 위치측정 성능을 입증하였다.

• 한국전문물리치료학회지
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• 제18권4호
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• pp.34-42
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• 2011

The lumbrical muscles contribute to the intrinsic plus position, that is simultaneous metacarpophalangeal (MCP) flexion and interphalangeal (IP) extension. The strength of the lumbrical muscles is necessary for normal hand function. However, there is no objective and efficient method of strength measurement for the lumbrical muscles. In addition, previous studies have not investigated the measurement of the cross-sectional area (CSA) of the lumbrical muscles using ultrasonography (US) and the relationship between lumbrical muscle strength in the intrinsic plus position and the CSA. Therefore, the purpose of this study was to identify the measurement method of the CSA of the lumbrical muscles using US and to examine the relationship between maximal isometric strength and the CSA of lumbrical muscles. Nine healthy males participated in this study. Maximal isometric strength of the second, third, and fourth lumbrical muscles was assessed using a tensiometer in the intrinsic plus position which isolated MCP flexion and IP extension. The CSA of the lumbrical muscles was measured with an US. The US probe was applied on the palmar aspect of the metacarpal head with a transverse view of the hand in resting position. There was no significant difference between maximal isometric strength of the lumbrical muscles, but the fourth lumbrical muscle was stronger than the others. The CSA of the lumbrical muscles was significantly different and the fourth lumbrical muscle was significantly larger than the second lumbrical muscle. There was moderate to good correlation between maximal isometric strength and the CSA of the lumbrical muscles. Therefore, we conclude that maximal isometric strength of the lumbrical muscles was positively correlated to the CSA of the lumbrical muscle in each finger, while the measurement of the CSA of the lumbrical muscles, using US protocol in this study, was useful for measuring the CSA of the lumbrical muscles.

• 대한물리치료과학회지
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• 제25권1호
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• pp.44-51
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• 2018

Background: In this paper, the relationship between the Cranio-Vertebral Angle (CVA) and the vital capacity in each position is reviewed, and the vital capacity in the position is studied. Methods: This study targeted 20 non-smoking female students of U university, which is located in Gyeongju-si. To review the Forward Head Posture (FHP) of each subject, CVA was measured, and FVC, FEV1, and FEF (25-75%) were measured and analyzed using a spirometer. Subjects were ordered to exhale three times with ease and then inhale up to their total lung capacity. After then, they were requested to exhale longer than six seconds. Then the inspiration and expiration were repeated. The measurement was executed in three positions, including supine, prone, and sitting. In each position the measurement was repeated twice, and a one-minute break was given between each cycle, so it was measured six times in total. SPSS 14.0 for Windows was used to analyze the data. The subjects' general properties were analyzed using descriptive statistics, and the correlation between the angle and the respiration variable result in each position was analyzed. The result of the respiration variable in each position was analyzed using the one-way ANOVA, and then a Scheffe post-hoc comparison was executed. Results: According to the analysis result of the correlation between the angle and respiration variable in each position, the sitting position and FEF (25-75%) showed a positive correlation (P<0.05). The respiration variable in each position showed a significant difference in FVC (p<0.05), and the Scheffe post-hoc comparison differed in prone and sitting positions. Conclusion: To increase the FVC of FHP patients, different exercises for each position can be applied, and the result of this study can be utilized as background data for further research.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.179-189
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• 2017

This paper is the fifth investigation on the methods of evaluating flow characteristics in a steady flow bench. In previous studies, several assumptions used in the steady flow bench were examined and it was concluded that the assumption of the solid rotation may lead to serious problems. In addition, though the velocity profiles were improved as the measuring position went downstream, the distributions were far from ideal regardless of the valve angle and evaluation position. The eccentricities were also not sufficiently small to disregard the effect on impulse swirl meter (ISM) measurement. Therefore, the effect of these distribution and eccentricity changes according to the positions needs to be analyzed to discuss the method of flow characteristics estimation. In this context, the effects of evaluation position on the steady flow characteristics were studied. For this purpose, the swirl coefficient and swirl ratio were assessed and compared via measurement of the conventional ISM and calculation based on the velocity by particle image velocimetry(PIV) from 1.75B, 1.75 times bore position apart from the cylinder head, to the 6.00B position. The results show that the swirl coefficients by ISM strictly decrease and the curves as a function of the valve lift become smooth and linear as the measuring position goes downstream. However, the values through the calculation based on the PIV are higher at the farther position due to the approach of the tangential velocity profile to ideal. In addition, there exists an offset effect between the velocity distribution and eccentricity in the low valve lift range when the coefficients are estimated based on the swirl center. Finally, the curve of the swirl ratio by ISM and by PIV evaluation as a function the measuring position intersect around 5.00B plane except at $26^{\circ}$ valve angle.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1537-1543
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• 1999

In this paper, PSD(Position Sensitive Detector) sensor system that estimates position for moving objects in 2D plane is developed. PSD sensor is used to measure the position of an incidence light in real-time. To get the position of light source of moving target, a new parameter calibration algorithm and neural network technique are proposed and applied. Real-time position measurements of the mobile robot with light source is examined to validate the proposed method. It is shown that the proposed technique provides accurate position estimation of the moving object.

• 조명전기설비학회논문지
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• 제22권3호
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• pp.66-73
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• 2008

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a 1-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

• 한국정밀공학회지
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• 제20권8호
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• pp.62-69
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• 2003

In most shipyards, the measurement of 3-dimensional relative position of pipes should be connected in the block depends on the manual operation. It results a very tedious and inefficient procedure, thus the proper measurement system is needed to improve productivity and accuracy. This paper describes the development of pipe measurement system including system concepts, measuring procedures, system calibration, and its accuracy and productivity. And also, the possibility and things to be improved for application in shipyard are discussed in this paper.