• International Journal of High-Rise Buildings
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• v.9 no.4
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• pp.387-396
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• 2020

While tall buildings are an essential building type to accommodate an ever-growing urban population, as buildings become taller and taller, many design challenges arise. As floor spaces are repeated vertically, the occupants' natural horizontal circulation-based social interactions are limited. As buildings become ever taller, safe evacuation to the ground level becomes more challenging in emergencies. With respect to safety as well as serviceability, one of the most fundamental design challenges of exceedingly tall buildings is their structural systems that make the physical existence of tall buildings possible. While many different design solutions can be sought to resolve these issues as well as other design challenges of extremely tall buildings, this paper investigates the potential of conjoined towers to create more livable and sustainable vertical environments. Emphasis is placed on the social and structural capabilities of conjoined towers in providing enhanced social interactions and more efficient ultra-tall structures. The related brief history of conjoined towers is presented. To understand their current status, contemporary design practices of conjoined towers are discussed. Lastly, a new concept of superframed conjoined towers developed for exceedingly tall building complexes is introduced through design studies. Though envisioning future tall buildings is challenging, conjoined towers can be among the strong candidates toward more livable and sustainable vertical urbanism.

• Fire Science and Engineering
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• v.25 no.1
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• pp.72-77
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• 2011

The effort of transferring some parts of urban functions to the underground space is growing trend among modem cities because of the limit of horizontal land use, the rise of land value, the diversification of human desire, etc. Thus, the basement of building and the subway station have deepened. It calls our attention to safety about evacuation from the underground space to the ground. Until now, the study about crowding walk in stairs has been progressed, focusing on the crowding walk that is going down the stairs, and there is no study about crowding walk that is going up the stairs. This study measured walking pace by crowd density that is going up the stairs in the subway station stairs making one-way movement of crowd. The actual survey showed that the mathematical relation 'V=0.638-0.0949p' determines going up walking velocity at a gradient of $23^{\circ}$, and the mathematical relation will be 'V=0.597-0.1067p' at a gradient of $30^{\circ}$, when it is converted, based on the average walking velocity of crowd by the slope of the stairs which is recommended by Architectural Institute of Japan.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.31-36
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• 2002

This paper concerns smoke propagation in tunnel fires with various size of fire source. Experiments carried out in model tunnel and those results were compared with numerical results. The Froude scaling law was used to scale model tests for comparison with larger scale tests. In order to validate for numerical analysis, temperature distribution of predicted data was compared with measured data. Examining the temperature distribution, we found that smoke layer does not come down under 50% of tunnel heights for a short tunnel heights for a short tunnel firs without ventilation. Front velocity of smoke layer is proportional to the cube root of heat release rate. And it is in good agreement with existing empirical expression and numerical prediction. In a short tunnel fire, horizontal propagation of smoke layer is more important than vertical smoke movement for evacuation plan.

• Journal of Veterinary Clinics
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• v.29 no.5
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• pp.368-371
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• 2012

The present study evaluated the outcome of use of thoracostomy tube tunneling technique under the latissimus dorsi muscle for the evacuation of postoperative pneumothorax induced by thoracotomy in 11 dogs. A stab incision was made through the skin and the latissimus dorsi muscle over the rib in the fifth intercostal space caudal to a surgical window. The thoracostomy tube with a Kelly hemostat was advanced into the thoracic cavity in a cranioventral direction through the sublatissimal tunnel. After tube placement, a # 1 nylon horizontal mattress suture was placed around the skin incision. The thoracostomy tube was removed after creating a negative pressure in the thoracic cavity. Dogs were monitored after surgery for pneumothorax, subcutaneous emphysema, clinical signs including dyspnea, and tube kinking in a muscle tunnel using physical examination and postoperative radiography. There was no tube kinking in the sublatissimal tunnel in 11 dogs on introducing the tubes into the thoracic cavity. The mean (${\pm}SD$) follow-up period was $19{\pm}10$ months. On postoperative radiography, there was no evidence of pneumothorax in 11 dogs. Subcutaneous emphysema was identified around the stab incision in a dog postoperatively. The subcutaneous emphysema disappeared spontaneously within 3 days. On postoperative physical examination, there was no evidence of dyspnea in 11 dogs. Our results suggest that the sublatissimal tunneling technique for thoracostomy tube placement is effective to prevent air leakage around the thoracostomy tube while the tube remains in the thoracic cavity and along the thoracostomy tunnel after tube removal. Tunneling under the latissimus dorsi muscle should be considered the thoracostomy tube placement technique to prevent iatrogenic pneumothorax with first priority.