HI EUNSEOK CHOI,
Each switching module has one LED labeled STATUS that provides information about the module and one numbered LED labeled LINK for each port on the module. Upon checking, RED means that "a test other than an individual port test failed". Do you have an active Smartnet Contract?
You may be hitting CSCue90589 bug:
Certain serial numbers of WS-X4648-RJ45-E have a Red LED at the far right corner. This will be visible through the sticker.
It is considered cosmetic and according to Cisco can be ignored.
It is reported to happen when WS-X4648-RJ45-E is inserted into a powered up chassis, so if this is your case I guess the issue MAY disappear after the whole box is powered down and up again.