• Archives of Reconstructive Microsurgery
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• v.3 no.1
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• pp.24-31
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• 1994

The heel, with its specialized fat for shock absorption at heel strike and large surface area for balance and weight bearing, is a important component of normal ambulation. Despite of distinguished improvement in the field of microsurgical free flaps, the choice of reconstruction of the heel has been remained controversial. We reviewed 22 cases of the heel reconstruction using vascularized free flaps from January, 1980 through May, 1993 at the Department of Orthopedic Surgery of Korea University Hospital. The results were as follows: 1. The etiology was traumatic in 21 cases, and chronic ulceration due to burn in 1. 2. The arteries used in free flaps were 11 dorsalis pedis arteries, 2 deep circumflex iliac arteries, 2 supeficial iliac arteries, 2 branches of lateral femoral circumflex iliac arteries, 2 radial arteries, and 3 thorcodorsal arteries. 3. The mean size of the vascularized bone was $4.5cm{\times}3.5cm$, and that of skin flap was $12.1cm{\times}9.2cm$. 4. Of the 22 cases, 19 had a successful outcome and 3 in failure, the causes of failure were thrombosis and infection.

• Fire Science and Engineering
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• v.13 no.1
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• pp.37-47
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• 1999

The spreading fire of very small floating particles after they are ignited is fast and t therefore dangerous. The research on this area has been limited to experiments and global simulations which treat them as dusts or gaseous fuel with certain concentration well m mixed with air. This research attempted micro-scale analysis of ignition of those particles modeling them as liquid droplets. For the beginning, the in-line array of fuel droplets is modeled by two-dimensional, unsteady conservation equations for mass, momentum, energy and species transport in the gas phase and an unsteady energy equation in the liquid phase. They are solved numerically in a generalized non-orthogonal coordinate. The single step chemical reaction with reaction rate controlled by Arrhenius’ law is assumed to a assess chemical reaction numerically. The calculated results show the variation of temperature and the concentration profile with time during evaporation and ignition process. Surrounding oxygen starts to mix with evaporating fuel vapor from the droplet. When the ignition condition is met, the exothermic reactions of the premixed gas initiate a and burn intensely. The maximum temperature position gradually approaches the droplet surface and maximum temperature increases rapidly following the ignition. The fuel and oxygen concentration distributions have minimum points near the peak temperature position. Therefore the moment of ignition seems to have a premixed-flame aspect. After this very short transient period minimum points are observed in the oxygen and fuel d distributions and the diffusion flame is established. The distance between droplets is an important parameter. Starting from far-away apart, when the distance between droplets decreases, the ignition-delay time decreases meaning faster ignition. When they are close and after the ignition, the maximum temperature moves away from the center line of the in-line array. It means that the oxygen at the center line is consumed rapidly and further supply is blocked by the flame. The study helped the understanding of the ignition of d droplet array and opened the possibility of further research.