• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.175-183
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• 2003

The purpose of this study was to analyze the kinetic energy of putter head and ball movements during the process of impact. Highly skilled 5 golfers(less than 1 handicap) participated in this study and the target distance was 3 m. Movements of ball and putter head were recorded with 2 VHS video cameras(60 Hz, 1/500 s shutter speed). Small control object($18.5{\times}18.5{\times}78.5\;cm$) was used in this sdtuldy. Analyzing the process of impact, putter was digitized before 0.0835 s and after 0.0835 s of impact. Ball was digitized 0.1336 s after impact. The results showed that the maximum speed was appeared at Impact and prolonged for a while. Contact point of the club head was within 0.7 cm to the z axis. After contacting the club head, the ball was moved above the ground level(slide) and returned to the ground with sliding and rolling. After contacting the ground, the speed of ball was relied on the surface of the ground. During impact, 70% of kinetic energy of club head has been transferred to the ball.

• Journal of Korea Multimedia Society
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• v.18 no.4
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• pp.492-498
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• 2015

In general, data packets from sensor nodes are transferred to the sink node in a wireless sensor networks. So many data packets are gathered around the sink node, resulting in significant packet collision and delay. In this paper, we propose an efficient packet transmission mechanism for multi-hop wireless sensor networks. The proposed mechanism is composed of two modes. One mode works between sink node and 1-hop nodes from sink. In this mode, data packets are transmitted in predefined time slots to reduce collisions. The other mode works between other nodes except sink node. In this mode, duplicated packets from neighbor nodes can be detected and dropped using some control signals. Our numerical analysis and simulation results show that our mechanism outperforms X-MAC and RI-MAC in terms of energy consumption and transmission delay.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.743-752
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• 1998

Numerical analysis for the flow and heat transfer in solid particle moving beds of heat exchangers is presented. The solid particle flow through the bundle of heat source tubes by the gravitational force. The heat energy is transferred through the direct contact of particles with the heat source tubes. The viscous-plastic fluid model and the convective heat transfer model are employed in the analysis. The flow field dominantly influences the total heat transfer in a heat exchanger. As the velocities of solid particles around the heat source tubes increase, the amount of heat transfer from the tubes increases. Some examples are presented to show the performance of the numerical model. The flow effect on the heat transfer is also studied through the examples.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.171-175
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• 1996

thermal diode is a device which allows heat to be transferred in one direction by convection due to difference of density of fluid. Vertical plate for heat collection and radiation are of utility for design of thermal diode. It was considered the transient process of air filled thermal diode with guide vane which combined rectangular and parallelogrammic shape enclosures. Gr was kept constantly on 1.60$\times$1010 and error range was $\pm$2% during the experiment. Nu was examined when inclined angle are 15$^{\circ}$and 45$^{\circ}$and, also the experiments was carried out with and without guide vane as well. Specially, The effect of guide vane was sensitive. Developed region inclined angle, which is characteristic of system.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.193-205
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• 1996

This paper deals with experimental study on thermal characteristics that a cooling fluid is affected to ice ball as being measuring the temperature in storage tank and ice ball governing the rate of heat storage. Distributor was taken as inlet geometry factor. flow rate of cooling fluid which was a brine were 2, 4, and 6LPM, and 8, 10, and 12$^{\circ}C$ in the temperature difference for dynamic factors with respect to three ice ball types(103, 96, 76mm). In case of in flowing cooling fluid, since inertia force is suppressed by lower flow rate the amount of heat was transferred to ice ball by heat conduction high because density difference is high. And in case of larger ice ball, a long-term storage was available because reaching time at steady state is relatively long. consequently, smaller ice ball could be suitable to a short-term storage.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.7
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• pp.367-372
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• 2006

A novel coil gun type actuator has been proposed and tested for its possibility as an actuator for a high voltage circuit breaker by experimental method. The 20kJ capacitor bank with the electrolytic condensers was charged up to 500V and discharged to a couple of 100 turn coils connected with parallel through a thyristor switch. The repulsive force between coil and the actuator made by copper conductor of 20kg reached up to 23,000 N, and over 800J of energy was transferred to the kinetic energy of the conductor. The experimental results showed that the coil gun type actuator has a good possibility for the high voltage circuit breaker.

• Fire Science and Engineering
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• v.11 no.4
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• pp.25-31
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• 1997

In this study, EMTP(Electromagnetic Transients Program) which is one of the most well-known computer simulation methods is used to collect the data for a power plant fault. EMTP is the program for an interpretation of the phenomena of electric transients, and is designed to manifest the data of the electric current and voltage etc. at the time of a power plant fault. By EMTP, I analyze the properties of the heat energy which are transferred from the electrics when a power plant fault brings out. In terms of the results of this study, it is able to measure the heat energy at a power plant fault (power transformer) and to be acquired of the related data. And moreover, these data are expected to be used as a standard for the protection of the fire owing to a high voltage power transformer fault.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.255.2-255.2
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• 2014

Electrode erosion is indispensable for atmospheric plasma systems, as well as for switching devices, due to the high heat flux transferred from arc plasmas to contacts, but experimental and theoretical works have not identified the characteristic phenomena because of the complex physical processes. Our investigation is concerned with argon free-burning arcs with anode erosion at atmospheric pressure by computational fluid dynamics (CFD) analysis. We are also interested in the energy flux and temperature transferring to the anode with a simplified unified model of arcs and their electrodes. In order to determine two thermodynamic quantities such as temperature and pressure and flow characteristics we have modified Navier-Stokes equations to take into account radiation transport, electrical power input and the electromagnetic driving forces with the relevant Maxwell equations. From the simplified self-consistent solution the energy flux to the anode can be derived.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.225-226
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• 2014

In multi-story buildings, heavy-weight floor impact noise propagates through multiple layers. In order to evaluate the influence of structural vibration and propagation, the actual twelve-story building was excited by an impact ball. Sound and vibration responses of each floor was measured using accelerometers and a microphone. Vibration characteristics and its transfer paths were different depending on the excitation floor locations due to differences in the structural characteristics. From the measurement result, transfer characteristics were quantified by statistical energy analysis. It was confirmed that the heavy-weight floor impact noise influence not only adjacent floor. The impact noise transferred and affected multiple layers.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.40-47
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• 1998

In the present study, depressions of the GMA weld pool due to the impact of droplet are numerically investigated. The numerical simulation is conducted on the basis of the Navier-Stokes equation and the volume of fluid(VOF) functions. The kinetic energy of transferring droplet makes a depression of the weld pool surface. The surface active element affects the depression of the weld pool. The droplets transferred efficiently to the bottom of the weld pool, along with electromagnetic force make the finger shape penetration at the high current GMAW.