• Korean Journal of Applied Biomechanics
• /
• v.26 no.3
• /
• pp.315-321
• /
• 2016

Objective: The aim of this study was to analyze effects of the toe-spring angle of bobsleigh shoes on start speed lap time to develop Korean-specific bobsled shoes suitable for winter environments and for domestic players on the basis of sports science and optimized biomechanical performance. Method: Seven Korean bobsleigh athletes participated in this study, with three pairs of sprint spikes from three companies (Type A, Type B, Type C). To analyze sprint lap time and forefoot bending angle for each shoe, participants were instructed to drag a sled 15 meters from the start line at a maximum sprint. forefoot bending angle was collected by a high speed camera, and lap time speed was measured. Results: Lap time for type B shoes was $3.52{\pm}0.17sec$, type A was $3.55{\pm}0.19sec$, and type C was $3.56{\pm}0.18sec$. Forefoot bending angles were: angle 1, $6.88{\pm}5.55^{\circ}$; angle 2, $9.23{\pm}6.38^{\circ}$; angle 3, $15.56{\pm}5.39^{\circ}$; angle 4, $9.54{\pm}3.85^{\circ}$; angle 5, $9.22{\pm}5.08^{\circ}$; angle 6, $7.66{\pm}6.44^{\circ}$; and angle 7, $4.30{\pm}6.24^{\circ}$ (p<.001). Forefoot bending in angle 3 was as follows: type A, $16.47{\pm}6.01^{\circ}$; type B, $14.30{\pm}4.96^{\circ}$; and type C, $15.90{\pm}5.17^{\circ}$. Conclusion: Hard outsoles and midsoles are better than soft type for reduced start lap time when developing a prototype Korean bobsled shoe.

• Journal of the Korean association of regional geographers
• /
• v.13 no.2
• /
• pp.156-170
• /
• 2007

The commerce and industry of Busan was developed because of good geographical conditions with harbor. After passing its settling-down and diffusing time, Busan has grown in the trade city. Busan has lost the competitive power of the port city since 2000, because of the weakness of its economic power which is caused by the secession of manufacturing industry and the decrease of resident population and foreign tourist. In order to overcome these weaknesses, it is necessary for Busan to take the innovative strategy for the activation of marine tourism. This goal can be achieved by the strong quality of the port city, the coastal terrain, the traditional industry and the international traffic. The aim of this paper is to explore the Innovative Strategy for the activation of marine tourism in Busan and to suggest the following proposal. First, the government must decide the base of marine tourism under the geography viewpoint of the coast and sea, and develope tourism resources after analyzing the identity of marine tourism base. Second, the core part along the selected bases of marine tourism must be constructed the tourism terminal as the landmark of Busan in order to concentrate foreign tourist. Third, after each base of marine tourism must become the resort for tourists, they are able to experience the activity of marine tourism in this resort. Therefore, each base must be specialized. Fourth, each base must be connected with the route of marine tourism Fifth, in order to overcome the off-season of marine tourism, winter tourism goods such as skates, skis, artificial sea-bathing pool, artificial swimming beach, artificial sled, artificial rock wall of coast, hot spring resort of salt water are required to be developed in the center of marine tourism base.

• Nuclear Engineering and Technology
• /
• v.53 no.9
• /
• pp.3068-3084
• /
• 2021

Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to experimentally assess the damage and vibrations of NPP buildings subjected to aircraft crash. In present Part I, two shots of reduce-scaled model test of aircraft impacting on NPP building were carried out. Firstly, the 1:15 aircraft model (weighs 135 kg) and RC NPP model (weighs about 70 t) are designed and prepared. Then, based on the large rocket sled loading test platform, the aircraft models were accelerated to impact perpendicularly on the two sides of NPP model, i.e., containment and auxiliary buildings, with a velocity of about 170 m/s. The strain-time histories of rebars within the impact area and acceleration-time histories of each floor of NPP model are derived from the pre-arranged twenty-one strain gauges and twenty tri-axial accelerometers, and the whole impact processes were recorded by three high-speed cameras. The local penetration and perforation failure modes occurred respectively in the collision scenarios of containment and auxiliary buildings, and some suggestions for the NPP design are given. The maximum acceleration in the 1:15 scaled tests is 1785.73 g, and thus the corresponding maximum resultant acceleration in a prototype impact might be about 119 g, which poses a potential threat to the nuclear equipment. Furthermore, it was found that the nonlinear decrease of vibrations along the height was well reflected by the variations of both the maximum resultant vibrations and Cumulative Absolute Velocity (CAV). The present experimental work on the damage and dynamic responses of NPP structure under aircraft impact is firstly presented, which could provide a benchmark basis for further safety assessments of prototype NPP structure as well as inner systems and components against aircraft crash.

• Journal of Korean Society of Forest Science
• /
• v.70 no.1
• /
• pp.63-71
• /
• 1985

To sled the superior clones of Populus alba ${\times}$ Populus glandulosa $F_1$, growth and some growth-related enzyme activities were examined for thirteen, two-year-old and fifteen, three-year-old trees at Seoul National University nursery in Suwon. Clonal differences in total dry weight per tree and leaf surface area per tree were significant at the 5% level. Significant correlations were found between total dry weight per tree and leaf surface area per tree (r=0.875), between leaf peroxidase activity per tree and total dry weight per tree (r=0.854), and between leaf nitrate reductase activity per tree arid total dry weight per tree (r=0.914). Leaf peroxidase and nitrate reductase activities per unit fresh weight of one-year-old tree increased with increasing leaf order numbers basipetally, reaching maximum values in the eighteenth and thirty-third leaves, respectively, and decreased gradually from those leaves to basipetal lower leaves. Clones 65-29-19, 66-15-3, 65-22-11, 66-14-93, and 66-26-55 among two-year-old trees, and clones 64-6-44, 66-14-29, 66-26-55, 65-22-11, and 68-1-54 among three-year-old trees showed greater leaf surface areas, peroxidase and nitrate reductase activities per unit leaf fresh weight than other clones, Growth of Populus alba ${\times}$ Populus glandulosa $F_1$ clones might be estimated from either leaf surface area per tree or peroxidase and nitrate reductase activities per tree. Therefore, measurements of leaf surface area and leaf enzyme activities appear useful to select superior Populus clones at early growth stages.