摘要 |
The fusion of a side wall may be made difficult by using a fusion-resistant material having light weight. Provided is a casing including a side wall having a multi-layer structure. In the casing, the side wall includes an outer wall, a fusion-resistant material provided at an inner side of the outer wall with a predetermined gap with respect to the outer wall, and an inner wall provided at an inner side of the fusion-resistant material with a predetermined gap with respect to the fusion-resistant material.
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