• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.541-542
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• 2009

• Economic and Environmental Geology
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• v.55 no.5
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• pp.521-529
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• 2022

Gravity exploration was conducted to determine the distribution of igneous complex related to lithium pegmatite in the Boam deposit of Uljin, Gyeongsangbuk-do, and the spatial relationship with the regional geology and ore bodies were studied. The gravity exploration result shows that the Boam deposit area is characterized by relatively low gravity anomaly that surrounds the deposit. The Boam deposit is located near the southwest-northeast directional boundary of gravity anomalies where igneous complex (granite gneiss) contacts with the Yuli and Wonnam groups in the southeast, Janggun limestone layers in the east-west direction, and Dongsugok metasedimentary rocks. While the western boundary in the southwest-northeast direction is relatively clear, there may also be unknown igneous complex that are not exposed on the surface at the eastern and southern boundaries because a relatively low gravity anomaly surrounds the deposit. The distribution characteristics of these hidden igneous complex will be used as useful data for predicting the distribution of the lithium pegmatite in the future.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.1
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• pp.72-78
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• 2007

Determination of the local vertical is not trivial for a moving vehicle and in general will require corrections for the Earth geophysical deflection. The vehicle's local vertical can be estimated by INS integration with initial alignment in SDINS(Strap Down INS) system. In general, the INS has drift error and it cause the performance degradation. In order to compensate the drift error, GPS/INS augmented system is widely used. And in the event that GPS is denied or unavailable, celestial navigation using star tracker can be a backup navigation system especially for the military purpose. In this celestial navigation system, the vehicle's position determination can be achieved using more than two star trackers, and the accuracy of position highly depends on accuracy of local vertical direction. Modern tilt sensors or accelerometers are sensitive to the direction of gravity to arc second(or better) precision. The local gravity provides the direction orthogonal to the geoid and, appropriately corrected, toward the center of the Earth. In this paper the relationship between direction of center of the Earth and actual gravity direction caused by geophysical deflection was analyzed by using precision orbit simulation program embedded the JGM-3 geoid model. And the result was verified and evaluated with mathematical gravity vector model derived from gravitational potential of the Earth. And also for application purpose, the performance variation of pure INS navigation system was analyzed by applying precise gravity model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4629-4635
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• 2012

This study was aimed at the relationship between peak EMG amplitude on low back muscles acting on L5/S1 and load center of gravity, trunk lateral bending while lifting an object. Musculoskeletal disorders including low back pain can occur even when handling heavy objects only once as well as when doing non-heavy materials repeatedly. 11 male subjects with average 23 age were required to lift a 15.8kg object symmetrically three times. Peak EMG amplitudes on 6 muscles related with L5/S1 were recorded and analyzed. The lifting conditions consisted of lifting symmetric load with no trunk lateral bending, asymmetric load with no trunk lateral bending, and asymmetric load with trunk lateral bending to the load center of gravity within an object. The results showed that peak EMG amplitude on back muscles contralateral to load center of gravity was observed greater in comparison with the symmetric load. Also, in case of lifting asymmetric load the posture with trunk lateral bending increased peak EMG amplitude on muscles contralateral to load center of gravity more than with no trunk lateral bending. This research can be used as one administrative intervention in order to reduce the low back pain incidence with suggesting workers that they keep the trunk not bending to load center of gravity if possible when lifting a heavy asymmetric object.

• Journal of the Korean School Mathematics Society
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• v.17 no.4
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• pp.771-804
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• 2014

The concept of the center of gravity is presently being introduced in elementary school curriculums and is broadly applied to Mathematics, Physics, and the Engineering field in University education which are mostly theoretical classes much separated from actual life in the practical educational field. In 2013, ${\bigcirc}{\bigcirc}$ University of Science and Gifted Education, had developed the multidisciplinary approach program of verifying the center of gravity for gifted students, but this program was reconstructed and applied to ordinary students and the effectiveness was analyzed to lay the foundation and generalize this convergence education. Including experiments for verifying the center of gravity in an object with a hollow interior and the existence of a center of gravity outside an object, I proposed realizing the calculations by considering the weight of the lever, the Principle of the lever being a core factor when finding the center of gravity. We altered the existing 8 step program to a 4 step program for the told 65 students from elementary, Junior and High School students, letting them freely select the class lecture by themselves. The analysis attained from surveys, debates and interviews showed that by precise error analysis, students achieved a higher success experience, showing us the importance of the development of a new convergence program.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.7-13
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• 1996

The kinematically admissible velocity field is developed for the analysis of extruded products. The curving of product in extrusion is caused by the linearly distributed longitudinal velocity on the cross-section of the workpiece at the die exit. In the analysis, the longitudinal velocity in extrusion direction is divided into the uniform velocity and the deviated velocity. In order to satisfy the requrement of the kinematically admissible velocity field, the average value of the deviated velocity should be zero. At the same time, it should linearly change with the distance form the center of gravity of the cross-section of the workpiece. The results of the analysis show that the curvature of product increses with increses in eccentricity of gravity center of the cross-section of workpiece at die entrance form that of the cross-section at the die exit. In the analysis, the longitudinal velocity in extrusion direction is divided into the uniform velocity and the deviated velocity. In order to satisfy the requrement of the kinematically admissible velocity field, the average value of the deviated velocity should be zero. At the same time, it should linearly change with the distance from the center of gravity of the cross-section of the workpiece. The results of the analysis show that the curvature of product increses with increses in ecentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.65-81
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• 2004

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The Pearson product moment correlation coefficient were used to determine and compare the relationships between the change in each component of the normalized angular momentum of the whole body about center of gravity and the actions of the extremities during different support phases. A level of significance at $\alpha$=.05 was set. After analyzing the angular momentum and correlation during support phase of the hop, step, and jump, the following findings are obtained: The actions of the arms created a side-somersaulting angular momentum about the whole body center of gravity toward the side of the free leg during the support phase of the step, and a somersaulting angular momentum about the whole body center of gravity during each support phase. The action of the free leg created a somersaulting angular momentum about the whole body center of gravity during the support phases of the hop and step.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.3
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• pp.335-342
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• 2009

Motion characteristics of a planing craft are sensitively changed according to its weight and longitudinal center of gravity. In this paper, planing craft model tests were performed in calm water for various test conditions and Froude numbers. Sinkage and trim were measured to analyze the relations between the attitudes of a planing craft and the weight and center of gravity of it. Theoretical formula for the prediction of the attitudes of a prismatic planing hull was modified so that it can be applied to the prediction of the attitudes of a non-prismatic planing hull, and the calculation results by the modified formula were in good agreements with the experimental data.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.245-249
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• 2006

The aim of this study is to design and develop the gait rehabilitation equipment that judge patient's movement of his/her center of gravity using pressure sensors, and to aid hemiplegic patients to balance themselves using an automatic stepper that changes the patient's center of gravity. It is hard to bear the weight on the affected side for hemiplegic patients. The gait rehabilitation equipment detects the footing phase of hemiplegic patient during training and moves the unaffected footing side of the stepper up and moves the affected footing side down simultaneously so that the patient's center of gravity can shift from unaffected side to affected side. The gait rehabilitation system was developed and applied for hemiplegic patients during exercise. Eight hemiplegic patients and one normal adult were studied. The developed gait rehabilitation system could judge not only the normal adult's intention but also the patient's intention to move his/her center of gravity. Even though the most of hemiplegic patients exercised in automatic mode and a few hemiplegic patients exercised in manual mode, the developed gait rehabilitation system can aid the hemiplegic patients to train more easily.

• International journal of advanced smart convergence
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• v.8 no.3
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• pp.78-86
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• 2019

Recently, IoT researches using sensor data based on embedded networks in various fields including healthcare and sports have been continuously attempted. This study analyzes golf ball mobility to support IoT application in golf sports field. Generally, since the difference in density occurs due to the condition of the inner material and the abnormal state at the time of the outer skin joining during the manufacturing of the golf ball, the weight of each subset is equal for any two points with the same radius in the sphere cannot be guaranteed. For this reason, the deflected weight of the sphere has the undesirable effect of hitting the ball in a direction in which the weight of the ball is heavy. In this study, it is assumed that there is a unique center of gravity of the ball, and even if the golf ball cannot be manufactured perfectly, it wants to establish the basic principle to accurately recognize or mark the putting line based on the center of gravity. In addition, it is evaluated how the mobility of the golf ball with a deviation from the center of gravity of the golf ball affects the progress path (or movement direction) and the moving distance (or carry distance) after the golfer hits. The basic model of the mobility of the golf ball can help the golfer exercise model and the correlation analysis. The basic model of the mobility of the golf ball can help the golfer exercise model and the correlation analysis.