• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.51-63
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• 2004

The purpose of this study was to investigate a three dimensional kinematic variables about the last stride and the release phase of the throwing technique for female javelin throwers. For the motion analysis, Six female javelin throwers were used as subjects. Three-dimensional coordinates were collected using the Kwon3D Motion Analysis Package Version 2.1 Program. Two S-VHS Video Cameras were used to record the locations and orientations of control object and the performances of the subjects at a frequency of 6.0 HZ. After the kinematic variables such as the time, the distance, the velocity, and the angle were analyzed about the last stride and release phase, the followings were achieved; 1. For the effectively javelin throwing, the subjects appeared to do long the approach time in the phasel of landing phase, and short the delivery time in release phase 2. In the release event, the other subjects except for subject A appeared to throwing in the lower condition than the height of themselves. This result showed to slow the projecion velocity. 3. For increase the projection vcelocity of the upper extremity joint in the release event, it appeared to do extend rather the shoulder angle than increase the extension of elbow joint. 4. The body of COG angle showed to gradually increase nearly at the vertical axis in the release event. But the front lean angle of trunk showed a small angle compare to increase of the body of COG angle. Therefore for the effectively momentum transmission of the whole body in the javelin, the front and back lean angle of trunk appeared to do fastly transfer the angle displacement in the arch posture or the crescent condition during the deliverly motion of the release phase.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.661-667
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• 2011

The purpose of the study was to compare selected kinematic variables between the female medalists and a Korean female javelin thrower at the IAAF World Championships, Daegu 2011. Three medalists and one Korean javelin thrower that participated in the Championships were videotaped using three high-speed cameras (300 frames/s, EX-F1 Exilim, Casio, Japan). This study identified the performance differences between the two groups. The results showed that the Korean female javelin thrower (KFJT) clearly had a greater delivery phase time than the female medalists. In order to throw farther, a thrower must exert a greater force to accelerate their body in a short time. This study also found that the release velocity of the KFJT was lower than that of the female medalists. The KFJT showed evidence of using her extremities differently to achieve the maximum release velocity. When comparing the inclination angle of the trunk across javelin throwers, the lowest value was recorded in the KFJT. Because the trunk position at release plays a significant role in determining the release height and release velocity, the KFJT should not rely on her upper extremities to achieve as high a release velocity as possible.

• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.631-638
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• 2011

This study had two purposes. The first was to analyze the period of the final record set by the male shot-putters in the IAAF World Championships, Daegu 2011 from the point of view of kinematics. The other was to identify an efficient movement for shot putting based on the analysis. The research used the eight finalists of in the championship as subjects. We analyzed the seven most important kinematic factors in shot putting based on the type of technique: the execution time of the delivery phase, release velocity, release angle, release, center of mass (COM) velocity, and shot trajectories. The analytical results showed the following average figures for the record 12 meters: execution time of the delivery phase: (0.19 s), release height: (2.06 m), release angle: ($34.68^{\circ}$), release velocity: (13.25 m/s), angular velocity of shoulder: ($922.38^{\circ}/s$), and angular velocity of pelvis: ($479.50^{\circ}/s$). Further, the results showed that the highest COM velocity was 2.25 m/s and the shot trajectories were close to a straight line in the release phase.

• Journal of the Korea Safety Management & Science
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• v.2 no.4
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• pp.33-43
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• 2000

The consequence analysis for the unconfined vapor cloud explosion(UVCE) accident by the continuous release of butane vapor was performed and effects of process parameters on consequences were analyzed in standard conditions. For the case of continuous release(87.8 kg/s) of butane vapor at 8 m elevated height in the debutanizing process of tile naphtha cracking plant operating at 877 kPa ＆ 346.75 K, we found that combustion ranges of dispersed vapor estimated by HMP model were 11.2~120.2 m and overpressures estimated by TNT equivalency model at 200 m were about 37.35~55.1 kPa. Also, overpressures estimated by Model UVCE I based on advective travel time to $X_{LFL}$ were smaller than those estimated by Model UVCE IIbased on real travel time between $X_{UFL}$ and $X_{LFL}$. At the same time, damage intensities at 200 m and effect ranges by overpressure could be predicted. Furthermore, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, sensitivities of overpressures for UVCE accident by the continuous release were about 5 kPa/atm.

• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.179-184
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• 2014

Purpose: This study was performed to investigate the release behavior of bioactive materials as a BMP-2 embedding on the porous titanium implant. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. Specimens diameter and height were 4mm and 10mm. Embedding materials were used to stamp ink. Sectional images, porosity and release behavior of porous Ti implants were evaluated by scanning electron microscope(SEM), mercury porosimeter and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were $8.993{\mu}m$ and 8.918%. Embedding materials were released continually and slowly. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. Therefore bioactive materials will be able to embedding to porous Ti implants. If the development of the fusion implant of the bioactive material will be able to have the chance to several patients.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.4
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• pp.618-623
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• 2004

This paper has dealt with the heat storage characteristics of gel type micro size latent heat storage material slurry. The heat release operation to the gel type micro size latent heat storage material slurry was carried out using hot air bubbles by direct contact heat exchange. This experiment was carried out using phase change material of n-paraffin so the heat release amount is higher than cold water system. The parameters of this experiment were concentration of latent heat phase change material, height of heat release bath and inlet velocity of hot air. The main results obtained are as follows : (1) The effect of concentration of latent heat phase change material dispersed with water is very affective to the direct contact heat exchange between hot air and gel type micro size latent heat storage material slurry. (2) It is clarified that the most effective concentration of latent heat phase change material dispersed with water exists around 20mass% at this type of direct heat exchange model experiment.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.8-14
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• 2004

This study analyzed dispersion characteristics and toxic effect in the small-scale continuous release of chlorine gas. We found that the Gaussian model using the Briggs' dispersion coefficient and the effective release height was better predicting experiments than the BM model. From chlorine concentrations calculated by Gaussian model, simulation results showed that the dispersion of chlorine was more affected by atmospheric stability and wind speed than release rate and that the toxic effect of chlorine gas was similar to the effect of parameters on chlorine dispersion. From effected areas with toxic criteria, damaged areas could be estimated to protect human.

• Coupled systems mechanics
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• v.8 no.1
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• pp.1-17
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• 2019

The present paper deals with delamination fracture analyses of the multilayered functionally graded non-linear elastic Symmetric Split Beam (SSB) configurations. The material is functionally graded in both width and height directions in each layer. It is assumed that the material properties are distributed non-symmetrically with respect to the centroidal axes of the beam cross-section. Sine laws are used to describe the continuous variation of the material properties in the cross-sections of the layers. The delamination fracture is analyzed in terms of the strain energy release rate by considering the balance of the energy. A comparison with the J-integral is performed for verification. The solution derived is used for parametric analyses of the delamination fracture behavior of the multilayered functionally graded SSB in order to evaluate the effects of the sine gradients of the three material properties in the width and height directions of the layers and the location of the crack along the beam width on the strain energy release rate. The solution obtained is valid for two-dimensional functionally graded non-linear elastic SSB configurations which are made of an arbitrary number of lengthwise vertical layers. A delamination crack is located arbitrary between layers. Thus, the two crack arms have different widths. Besides, the layers have individual widths and material properties.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.639-647
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• 1999

Experimental methods of plume dispersion in convective boundary layer using a composite turbulence water tank have been established through (ⅰ) manufacturing of water tank system, (ⅱ) providing of tracer whose volatility is relatively low, (ⅲ) development of software for image processing of dispersed particles in fluid, and (ⅳ) application of appropriate similarity law. Using these methods, the vertical dispersion coefficient $$\sigma$_2$ at long distances on mesoscale and the centerline height $Z_c$ of plumes have been measured. Measurement of $$\sigma$_2$ have been validated through comparison with CONDORS field experiments, and analysed with respect to the intensity of heat flux and mechanical turbulence as well as plume release height. Downwind distance where plume center height approaches to final level has also been analysed in respect of these three parameters.

• Fire Science and Engineering
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• v.32 no.1
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• pp.16-23
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• 2018

In a closed-compartment with various configurations, the correlation that can predict the maximum heat release rate (HRR) with the changes in internal volume and fire growth rate was investigated numerically. The volume of the compartment was controlled by varying the length ratio based on the bottom surface shape of the ISO 9705 fire room, where the ceiling height was fixed to 2.4 m. As a main result, the effect of a change in ceiling height on the maximum HRR was examined by a comparison with a previous study that considered the change in ceiling height. In addition, a more generalized correlation equation was proposed that could predict the maximum HRR in closed-compartments regardless of the changes in ceiling height. This correlation had an average error of 7% and a maximum error of 19% for various fire growth rates when compared with the numerical results. Finally, the applicability of the proposed correlation to representative fire compartments applied to the domestic performance-based design (PBD) was examined. These results are expected to provide useful information on predicting the maximum HRR caused by flashover in closed-compartments as well as the input information required in a fire simulation.