• Journal of Industrial Technology
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• v.19
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• pp.173-178
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• 1999

In many areas of technology there are machines and systems controllable in up to six degrees of freedom. Helicopters and underwater vehicles, industrial robots are among the first representatives of this category. They need six degrees of freedom in order to move and orient within their workspace. An even broader and more explosively growing area is 3D computer graphics and virtual environment. In this work, functions of 3D input device are described and two types of commercial 3D input device are presented. Then, a preliminary experiment of a low cost 6 axis force/moment sensor is presented that can also be sued as a 3D input device. A low cost force/moment sensor and its application in robot teaching experiment is described. It computes the direction of 3 components of the force and 3 components of the moment applied by human holding the sensor by hand. The concept is shown by an experiment where the tool position and orientation of a robot in 3 dimensional space is controlled by the proposed sensor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.179-183
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• 2000

This paper is concerned with achieving the high motion accuracy of linear motion bearing guide according to estimate accuracy average effect of bearing. Accuracy average effect can be obtained b analysis the relationship between motion error of the table and spatial frequency of the rail form error. And influences of ball diameter, ball number, and clock length on block motion error and block number on the table motion error are analyzed theoretically. In addition to, a simple experiment is performed in order to verify theoretical result.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.196-201
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• 2017

A cylindrical structure has a very long period of heave and pitch motion response in ocean waves. To obtain the dynamic stability of a cylindrical structure, it is necessary to obtain the suitable metacentric height (GM). However, in a structure with sufficient metacentric height, Mathieu instability can occur if the natural frequency of the heave motion is double the natural frequency of the roll and pitch motion. This study carried out numerical calculations and experiments for vertical-axis wind turbines with cylindrical floaters, which had three different centers of gravity. In the regular wave experiment, the divergence of the structure motion without yaw was observed when the natural frequency of the heave motion was double the natural frequency of the roll and pitch motion. In the irregular wave experiment, the motion spectra of the structures with the different centers of gravity were compared, and one was very high when the natural frequency of the heave motion was double the natural frequency of the roll and pitch motion.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.127-136
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• 2018

The motion response of floating structures is of significant concern in marine engineering. Floating structures can be disturbed by waves, winds, and currents that create undesirable motions of the vessel, therefore causing challenges to its operation. For a floating structure, mooring lines are provided in order to maintain its position; these should also produce a restoring force when the vessel is displaced. Therefore, it is important to investigate the tension of mooring lines and the motion responses of a twin barge when moored to guarantee the safety of the barge during its operation. It is essential to precisely identify the characteristics of the motion responses of a moored barge under different loading conditions. In this study, the motion responses of a moored twin barge were measured in regular waves of seven different wave directions. The experiment was performed with regular waves with different wavelengths and wave directions in order to estimate the twin-barge motions and the tension of the mooring line. In addition, the motion components of roll, pitch, and heave are completely free. In contrast, the surge, sway, and yaw components are fixed. In the succeeding step, a time-domain analysis is carried out in order to obtain the responses of the structure when moored. As a result, the Response Amplitude Operator (RAO) motion value was estimated for different wave directions. The results of the experiment show that the motion components of the twin barge have a significant effect on the tension of the mooring lines.

• Journal of the Ergonomics Society of Korea
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• v.27 no.2
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• pp.49-57
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• 2008

This study aims to investigate the effect of handle angles of pliers on performance, wrist motion and subjective rating of satisfaction. An experiment was conducted, in which handle angle of pliers was used as independent variable and 14 subjects participated. Based on the literature survey, plier handles angled at 0$^{\circ}$, 10$^{\circ}$, 20$^{\circ}$, 30$^{\circ}$ and 40$^{\circ}$ were adopted in the experiment. The subjects were instructed to bend iron plates by 90$^{\circ}$ and to cut wires as soon as possible. The results revealed that 1) handle angles of pliers have significant effect on wrist motion and satisfaction(p<0.0001); 2) handle angles of pliers did not affect performance of completing tasks irrespective of types of tasks done in the study; 3) in the initial stage of windup, plier with handle angled at 20$^{\circ}$ produced the least wrist motion of deviation in task of bending iron plates, while plier with handle angled at 40$^{\circ}$ did in task of cutting wires; 4) degree of satisfaction was maximized when handle of pliers was bent by 20$^{\circ}$ in both tasks. On the basis of the results, it is recommended that handle of pliers be bent by 20-30$^{\circ}$ for reducing musculoskeletal disorders related to pliers.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.212-217
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• 1993

In this paper, characteristics of the motions of a human arm are investigated experimentally. When the conditions of the target point are restricted, human adjusts its trajectory and velocity pattern of the arm to fit the conditions skillfully. The purpose of this work is to examine the characteristics of the trajectory, velocity pattern, and the size of the duration in the following cases. First, we examine the case of point-to-point motion. The results are consistent with the minimum jerk theory. However, individual differences in the length of the duration can be observed in the experiment. Second, we examine the case which requires accuracy of positioning at the target point. It is found that the velocity pattern differs from the bell shaped pattern explained by the minimum jerk theory, and has its peak in the first half of the duration. When higher accuracy of the positioning is required, learning effects can be observed. Finally, to examine the case which requires constraint of the arm posture at the target point, we conduct experiments of a human trying to grasp a cup. It is considered that this motion consists of two steps : one is the positioning motion of the person in order to start the grasping motion, the other is the grasping motion of the human's hand approaching toward the cup and grasping it. In addition, two representative velocity patterns are observed : one is the similar velocity pattern explained in the above experiment, the other is the velocity pattern which has its relative maximum in the latter half of the duration.

• Journal of The Korean Association For Science Education
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• v.24 no.5
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• pp.886-901
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• 2004

The purpose of this study was to document the changes in astronomical concepts for preservice and inservice elementary school teachers after being presented with the newly devised Earth Motions Centric Solar System Model. The subjects of the study were 31 preservice and 30 inservice elementary schools teachers in the Jeonbuk Province. First, the author investigated the naive theories of the subjects, and then, compared that data to the data obtained after their exposure to the model. The total number of items on the instrument for this study was 10. These items included questions about the motion of interior planets, the phases and sizes of interior planets, and the motion of exterior planets and comets. After analyzing the answers to the items before the experiment, the author was able to confirm the existence of the naive theories regarding astronomical phenomena. Also, after the experiment, the author was able to observe the conceptual change in thought of the preservice and inservice elementary school teachers. Results showed that learning through the new model had positive effects on the preservice and inservice elementary school teachers' conceptualization of the interior planets' motion, phases and sizes, and the exterior planets' motion.

• Journal of Korea Game Society
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• v.9 no.5
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• pp.63-72
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• 2009

I-phone presented a new mobile control type by the introducing motion recognition sensor and that influenced on game application development so that led a lot of games using kinds of sensors. In this paper, we divided the game enjoyment into 5 factors for the embodiment of the sensor's influence direction on the enjoyment. We experimented two game, which have same content, different devices in using motion recognition sensor or not for clarifying the distinction between devices. As a experiment source game, we used Cooking Mama, as a experimental device, we used I-pod touch and NDS. This experiment shows a motion recognition sensor control's enjoyment is far superior to touch sensor. This sensor got high marks on every fun factors, stimulus, absorption, empathy, accomplishment and variation. Especially, stimulus and empathy showed great differences. In this case, we found the fact that extended communication between the gamer and the device can be fun.

• Journal of The Korean Association For Science Education
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• v.16 no.1
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• pp.51-60
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• 1996

The purpose of this study is to develope and analyze a test for the assessment of physics inquiry experiment. To do this, three experiments about 'analysis of motion', 'the relation of force and acceleration', and 'free fall motion' in high school physics textbooks were chosen, and 5 scientific inquiry domains and 16 science process skills have been specified. For each experiments, test sheet of $29{\sim}44$ questions for assessing students' ability about physics inquiry experiment were developed on the basis of the scientific inquiry processes developed earlier. After instruction about 3 experiments mentioned above, a test was administered to the students who took experiment. After the adminstration of a test, the ratio of correct answers, discrimination index, and reliability were analyzed. Using the ratio of correct answers, we can determine item difficulty. Through the D.I(discrimination index), we can find which items can discriminate the students who took experiment well from those who took experiment badly, and we can also find the stability of a test result by the reliability analysis. The test developed in this study were also administered to the students who did not take experiments, and the results were compared with the those of the students who took experiments. With the comparison by chi-square method, we could find which items can discriminate the students who took experiments from those who did not take experiments.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.113-115
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• 2003

Recently, many linear motion generators and are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic cone type loud speakers tostirling engine driven linear reciprocatings, alternators, compressors, textile machines etc. In this paper the dynamic performance with load is computed by a general purpose method, which the equation of electromagnetic field, the equation of electric circuit and the equation of motion are coupled together. We fumed out the driving system and the dynamic characteristics of current, voltage and displacement is confirmed experiment.