To produce a life jacket that fits users both comfortably and stably, we developed a life jacket pattern based on the three-dimensional (3D) shape of the human body, with foam flotation material of different thicknesses used in different sections to achieve the required buoyancy and facilitate movement. We created a nonstandard life jacket for water sports that can adopt free design for canoeing and kayaking. Engineering design process and 3D technology were used to create the ergonomic 3D life jacket, which comprised an inner pattern, a polyethylene (PE) foam pattern for proper buoyancy in water, and the outer pattern. We developed a layering method for achieving the heterogeneous thickness of the life jacket and its outer pattern considering the ergonomic aspects of the 3D human body curvature and movability. The pattern expansion length was calculated to enlarge the outer pattern of each panel covering the varying thicknesses of life jacket and spacing for torso flexion. The calculation formula for this length was useful in increasing or decreasing the life jacket’s buoyancy, which was affected by the PE-foam thickness. Human-subject wear tests were performed in air and water to evaluate the developed life jacket. The developed life jacket had improved functionality. Significant differences ( P ≤ 0.01) existed between the newly developed and conventional life jackets in air, in terms of the overall comfort, freedom of rowing movement, and fits in the chest and waist areas. Significant differences ( P ≤ 0.05) also existed in water in terms of the overall fit and prevention of separation from the shoulder due to buoyancy.
Purpose This study aims to provide information on how to monitor the temperature setting of a heating device in order to implement a heating unit successfully in the smart clothing by observing voluntary heating behavior of wearers.Design/methodology/approach Subjects wearing base layers and additional clothing were asked to turn on and off the switch when wanted in the cold environmental chamber. Tolerable range of skin temperature (TST) depending on the location of body was obtained by observing the temperature at the time when the heating device was turned on and off during a rest–running–rest protocol.Findings The TST was 32.8–49.4 °C and decreased to 31.3–37.6 °C around abdomen and back waist, respectively. Changes in the wearers' voluntary control behavior were observed depending on the individual's level of cold-sensitivity and activity level of rest and running. TST was 35.8–49.4 °C (Rest 1: rest before exercise), 40.0–42.0 °C (Running) and 35.3–43.2 °C (Rest 2: rest after exercise) for cold-sensitive group, whereas it was 32.8–36.2 °C (Running) and 34.4–45.7 °C (Rest 2: rest after exercise) for cold-insensitive group.Originality/value In this study, results with detailed body locations and wearer's thermal sensitivity provide practical references for the implementation of a heating device to the comfortable multilayered smart clothing.
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