• 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.

• 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.

• Economic and Environmental Geology
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• v.32 no.3
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• pp.281-291
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• 1999

This study presents the gravity data with GPS survrying and the geophysical profiles at the Choogaryeong Rift Valley. And in determing geoid by GPS measurement, survey control points (SCP) whoch built by the Republic of Korean Army are used. Seventy nine SCP and the two triangulation stations are reviewd by GPS. Digital terain model is under for terrain analysis. The analyses of the gravity surveying with GPS are as follows. The low values of the negative Bouguer anomalies represent the high elevation terrain. The Bouguer anomalies show the decrrasing trend toward the eastern part of the study area. Characteristics of free-air anomalies are related with terrain elevation. The regional gravity anomalies decreas toward the eastern part of the study area. The trends of variations are associated with the thermotectonic and geologic structure beneath the Choogaryeong Rift Valley. The most parts of the study area represent negative residual gravity anomalies due to the low dencity of sedimentary cover in the Rift Valley. There are three valleys and four mountains in the direction of NE-SW or NNE-SSW which are structured by the geological features.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.229-232
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• 2002

This paper describes the development of robot's finger 3-axis force sensor that detects the Fx, Fy, and Fz simultaneously fur stably grasping an unknown object. In order to safely grasp an unknown object using the robot's fingers, they should detect the force of gripping direction and the force of gravity direction, and perform the force control using the detected farces. The 3-axis force sensor that detects the Fx, Fy, and Fz simultaneously should be used for accurately detecting the weight of an unknown object of gravity direction. Thus, in this paper, robot's finger for stably grasping an unknown object is developed. And, the 3-axis farce sensor that detects the Fx, Fy, and Fz simultaneously fur constructing a robot's finger is newly modeled using several parallel-plate beams, and is fabricated. Also, it is calibrated, and evaluated.

• Journal of Korea Foresty Energy
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• v.22 no.1
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• pp.1-7
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• 2003

The purpose of this study was to investigate variabilities in green moisture content, specific gravity and shrinkage in the stems of a Larch(Larix leptolepis) to provide fundamental information for technical processes. There were significant differences in green moisture contents, specific gravity and shrinkage between heratwood and sapwood. The green moisture content was correlated negatively with the height in the sapwood. On the other hands, in the heratwood, there was a positive correlation between moisture content and the height. There were no significant differences in specific gravity between south-bound and north-bound directions in both heartwood and sapwood. There were no significant differences in specific gravity due to the height in sapwood, but significant differences were foundin heartwood. There were no significant differences in shrinkage between south-bound and north-bound directions, and due to the height in most of heartwood and sapwood. However, shrinkage in north-bound direction was higher than that of in the south-bound direction in some sapwoods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1167-1174
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• 2004

The method to consider gravity effect on the performance of a condenser is developed, and a simple condenser having 'nU' type two circuits is analyzed. Each circuit has the same length and inlet air-side operational conditions. The only difference between two circuits is the direction of refrigerant flow, which is exactly opposite each other between the upper 'n' type circuit and the lower 'U' type circuit. It is shown that the gravity makes the distribution of refrigerant flow uneven in the two circuits at lower refrigerant flow rates; heat transfer rate also becomes uneven. Moreover, much of the refrigerant exists as liquid state in the circuit having low refrigerant flow rate, which will make the cycle balance unstable in the refrigeration cycle system like a heat pump.

• Journal of the Korean Wood Science and Technology
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• v.23 no.1
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• pp.28-34
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• 1995

Korean pine(Pinus koraiensis S. et Z.) is an economically important species in Korea because it will be harvested largely within next 20~30 years. The purpose of this study was to investigate changes in green moisture content, specific gravity and shrinkage in the stems of a Korean pine trees to provide fundamental information for technical processes. The followings are the results of this study. 1. There were about 110% differences in the heartwood and sapwood' green moisture contents (heartwood=59.5%; sapwood=170.6%). 2. There were no significant differences in average volumetric shrinkage between heratwood and sapwood, even though there were significant differences in moisture contents between them. Therefore, moisture content did not significantly influence on the shrinkage. 3. There was no significant relationship between height and shrinkage in heartwood. However, in the sapwood, shrinkage was highly correlated with the height. 4. Shrinkage levels were the most significant in south-bound direction and least significant in north-bound direction in both heartwood and sapwood. 5. There was a positive correlation between specific gravity and shrinkage in the sapwood. However, no such a relationship was found in the heartwood.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.297-300
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• 2002

In this study, the deformation of the free surface motion of a magnetic fluid for the change in electromagnetic force is discussed and carried out theoretically and experimentally on the basis of Rosensweig Ferrohydrodynamic Bernoulli Equation. While applied magnetic fields are induced by 4$\times$4 electromagnet located under the magnetic fluid, the surface of the magnetic fluid is formed the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body farce. In case, magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. thus, the device of a magnetic fluid proposed the surface actuator. The device of surface deformation as well comparison between numerical simulation and experiments as will be presented.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.29-37
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• 2005

In this study, the control of the free surface deformation of a magnetic fluid for the change in electromagnetic force is discussed. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. Magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage sealing, oscillator for surface control, boundary layer control, MHD, flow control, flow using magnetic levitation system and surface actuator. This study show the deformation of surface rise due to the intensity of the magnetic field and possibility of two-dimensional control of magnetic fluid through the feedback data of hall sensor.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.74.1-74.1
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• 2010

Using two-dimensional numerical hydrodynamic simulations, we investigate the regulation of star ormation rates in turbulent, multiphase, galactic gaseous disks. Our simulation domain is xisymmetric, and local in the radial direction and global in the vertical direction. Our models nclude galactic rotation, vertical stratification, self-gravity, heating and cooling, and thermal onduction. Turbulence in our models is driven by momentum feedback from supernova events ccurring in localized dense regions formed by thermal and gravitational instabilities. Self-onsistent radiative heating, representing enhanced/reduced FUV photons from the star formation, s also taken into account. Evolution of our model disks is highly dynamic, but reaches a quasi-teady state. The disks are overall in effective hydrostatic equilibrium with the midplane thermal ressure set by the vertical gravity. The star formation rate is found to be proportional pproximately linearly to the midplane thermal pressure. These results are in good agreement with the predictions of a recent theory by Ostriker, McKee, and Leroy (2010) for the thermal/dynamic equilibrium model of star formation regulation.