• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.603-610
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• 2011

The long jump motions of 8 finalists in the women's long jump at the IAAF World Championships, Daegu 2011 were analyzed, and the kinematic characteristics of their techniques were investigated. The kinematic characteristics of the long jump motion of the 8 finalists were as follows. In the run-up phase, the length of the 2 stride was $108{\pm}6.92%$ that of the 3 stride. The length of the 1 stride was $91{\pm}5.78%$ that of the 2 stride. The change in the height of the center of gravity was $0.07{\pm}0.03$ m. The maximum velocity during the run-up phase was $9.44{\pm}0.13$ m at the 1 stride. In the take-off phase, the horizontal velocity, vertical velocity, reduction in horizontal velocity were $7.80{\pm}0.15$ m/s, $2.96{\pm}0.14$ m/s, and $1.64{\pm}0.19$ m/s, respectively. The minimum knee angle and take-off angle were $151{\pm}8.89^{\circ}$ and $20.7{\pm}1.03^{\circ}$, respectively. In the flight phase, the flight time and maximum height of the center of gravity were $0.78{\pm}0.03$ s, and $1.60{\pm}0.05$ m, respectively. In the landing phase, the landing length was $0.50{\pm}0.07$ m. The trunk angle, knee angle, and hip angle were $74{\pm}18.75^{\circ}$, $131{\pm}10.45^{\circ}$, and $82{\pm}9.03^{\circ}$, respectively. The kinematic characteristics of the motion of a good long jump were as follows. The reduction in the horizontal velocity in the take-off phase was minimized, and the maximum velocity of the run-up was maintained. The vertical velocity in the take-off phase was increased using a rapidly extended knee and high center of gravity.

• Journal of the Society of Disaster Information
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• v.8 no.1
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• pp.10-17
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• 2012

The purpose of this study is to make people acknowledge the danger of the air terror and provide measures to prevent a recurrence of the accident and find required security. Also, the air terror is categorized into aircraft and airport and take steps to come up with preventive measures against the air terror by finding a countermeasure and precaution. The following steps should be checked to take precautionary measures against the air terror. major security crackdown and the need for a further security check should be conducted to prevent terrorists from boarding the aircraft, security around the airport needs to be tightened up by training the airport workers and promoting emergency situations, airport sheriffs and armed guards should be on patrol for the safety of the cabin, new measures of efficient security for in and around the airport and its facilities should be set up to tighten up security of baggage.

• Textile Coloration and Finishing
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• v.28 no.2
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• pp.101-108
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• 2016

Polypropylene(PP)/multiwalled carbon nanotubes(MWCNT) nanocomposites films and PP/poly(vinyl alcohol)/CNT nanocomposites films were prepared through melt mixing method by the extruder. The PP/CNT nanocomposites films, which contain CNT of a variable content, were prepared for the first time and research on a appropriate content of the CNT on the PP/CNT nanocomposites films was conducted. The effects of take-up speed of the extruder on the mechanical and chemical properties of the PP/CNT and PP/PVA/CNT nanocomposites film were studied. Field emission scanning electron microscope(FE-SEM) was used to examine the surface morphology and the DSC measurement and tensile test were conducted. It was found that the properties decreased when take-up speed was increased.

• The Research Journal of the Costume Culture
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• v.21 no.6
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• pp.967-973
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• 2013

During high speed sewing, the needle thread is exposed to dynamic loading, short strike loading, inertia forces, friction, rubbing, force of check spring, bending, pressure, friction, impact, shock and thermal influence. The dynamic thread loading/tension alters throughout the stitch formation cycle and along its passage through the machine. The greatest tensile force occurs at the moment of stitch stretching, when the take up lever pulls for required thread length through the tension regulator. These stresses act on the thread repeatedly and the thread passes 50-80 times through the fabric, the needle eye and the bobbin case mechanism, before getting incorporated into the seam, which result in upto 40% loss in tensile strength of the sewing thread. This damage in the sewing thread adversely affects its processing and functional performance. In this paper, the contribution of dynamic loading, passage through needle and fabric, and bobbin thread interaction in the loss in tensile properties has been studied. It is observed that the loss in tensile properties occurs mainly due to the bobbin thread interaction. Dynamic loading due to the action of take up lever also causes substantial loss in tenacity and breaking elongation of cotton threads.

• Korea-Australia Rheology Journal
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• v.12 no.2
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• pp.107-117
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• 2000

Prediction of the product shape in sheet casting process is performed from the numerical simulation. A three-dimensional finite element method is used to investigate the flow behavior and to examine the effects of processing conditions on the sheet produced. Effects of inertia, gravity, surface tension and non-Newtonian viscosity on the thickness profile of the sheet are considered since the edge bead and the flow patterns in the chill roll region have great influence on the quality of the products. In the numerical simulation with free surface flows, the spine method is adopted to update the free surface, and the force-free boundary condition is imposed along the take-up plane to avoid severe singularity problems existing at the take-up plane. From the numerical results of steady isothermal flows of a generalized Newtonian fluid, it is shown that the draw ratio plays a major role in predicting the shape of the final sheet produced and the surface tension has considerable effect on the bead thickness ratio and the bead width fraction, while shear-thinning and/or tension-thickening viscosity affect the degree of neck-in.

• The Journal of Information Technology
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• v.12 no.1
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• pp.35-56
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• 2009

After Chinese reforms and market opening, China actively started working on ways to attach importance to the ocean and it's maritime strategy has been developed and carried out by external and internal factors. We can take two things as external factors attributed to China's marine strategy. The first one is maritime environment change in the East Asian region and the second one is the strategic importance of Taiwanese Straits and the South China Sea. And we can take about national strategy, security strategy, and change of foreign policy as internal factors. China recognizes the ocean as a major step to achieve a goal of national development. The main goal of China's marine strategy in the 21st century is to secure marine transportation and marine resources and to make peaceful maritime environment in the ocean to keep up with their economic development by opening itself to the world. China has strengthened their defense abilities to act against threat of national security by modernizing sea forces and increased national power by building up the marine power. It is expected that China will continue to seek more aggressive maritime strategy on matters of national security as well as pour heir efforts into making economic development and obtaining energy resources. This will also be one factor making new dynamics between countries in and around the East Asian region.

• Korea-Australia Rheology Journal
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• v.13 no.1
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• pp.1-12
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• 2001

This paper describes the application of our recently developed two-phase model for flow-induced crystallization (FIC) to the simulation of fiber spinning and film blowing. 1-D and 2-D simulations of fiber spinning include the combined effects of (FIC), viscoelasticity, filament cooling, air drag, inertia, surface tension and gravity and the process dynamics are modeled from the spinneret to the take-up roll device (below the freeze point). 1-D model fits and predictions are in very good quantitative agreement with high- and low-speed spinline data for both nylon and PET systems. Necking and the associated extensional softening are also predicted. Consistent with experimental observations, the 2-D model also predicts a skin-core structure at low and intermediate spin speeds, with the stress, chain extension and crystallinity being highest at the surface. Film blowing is simulated using a "quasi-cylindrical" approximation for the momentum equations, and simulations include the combined effects of flow-induced crystallization, viscoelasticity, and bubble cooling. The effects of inflation pressure, melt extrusion temperature and take-up ratio on the bubble shape are predicted to be in agreement with experimental observations, and the location of the frost line is predicted naturally as a consequence of flow-induced crystallization. An important feature of our FIC model is the ability to predict stresses at the freeze point in fiber spinning and the frost line in film blowing, both of which are related to the physical and mechanical properties of the final product.l product.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.55-63
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• 2012

As of Dec. 31, 2011, the number of nation's escalators accounts for 24,248 units, 5.4% of total elevators in our country, safety accidents take up as many 539 case, 55.2% of total elevators' safety accidents. Escalator safety accidents show high incident ratio of primary safety accidents breaking out by users' careless and abnormal use type, taking up multi-caused accident, which mainly take place from vulnerable age groups such as children under 13, and elders above 65. The Government will have to devote itself for policy and support for the establishment of safety management system fit for current state, the revitalization of preventive education for safety accident, the enhancement of safety awareness to escalators' users in order to secure escalator safety environment on an international level and support domestic industrial development.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.143-151
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• 2021

The purpose of our study is to confirm the trend of the muscle activity of the trunk and lower limb muscles by the attack method and phase during volleyball exercise. To achieve this purpose, spike serve and spike were conducted for 9 male middle school students, and at that time, it was divided into four phase, such as run jump, take off, impact, and follow, and the rectus abdominis, erector spine, and left rectus femoris, left biceps femoris, left anterior tibialis, left gastrocnemius midialis, right rectus femoris, right biceps femoris, right anterior tibialis, right gastrocnemius midialis, were examined. Spike serve and spike were each performed three times, and randomly cross-allocated to extract accurate data. We was no difference in all muscles according to the attack method, and the muscle activity of the rectus abdominis was highest in the impact phase and the muscle activity of the vertebral spine muscle was highest in the close-up phase. In addition, all of the measured left and right lower limb muscles showed the highest muscle activity between the assisted devices. As a result, We found out that regardless of the method of spike serve and spike, the lower limbs in the run-up phase for a high jump, the vertebrae in the take off phase, the preparation phase for hitting the ball strongly, and in the impact phase at the moment of hitting the ball. It can be seen that it exerts the greatest power in the rectus abdominis.

• Journal of Technology Innovation
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• v.11 no.1
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• pp.215-236
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• 2003

According to Gerschenkron (1962), the industrialization of relative backward countries was characterized in a systematically varying fashion by sudden spurts. With respect to the technological loaming, its globalization, and the subsequent development of technological capability, Korea, a catching-up nation had some experiences of identifiable discontinuities in her technological development in various industries. This study examines a developmental path of technological catching-up in Korean mobile telecommunication, especially CDMA industry and argues that investment and networking capability play an infrastructural role in accumulating her technological capability. Note that the technological experiences in high-tech industries have made Korea take a different technological path with respect to the previous industrialization. For this purpose, it proposes an analytical framework for examining a developmental path of Korean catching-up players. In addition, it analyzes the case of the Korean mobile telecommunication industry on the basis of the framework, and identifies a developmental path from the case analysis.