How to compile android, changing the default values ​​set in Settings

We board on the Android system power management still have questions, you can only shut down once asleep restart. Android's settings in the default sleep time is "1 minute without operation." After each system must manually refresh to 30 minutes.
I want the default value for this setting to 30 minutes, but do not know the time of the default value which is in the android source code files.
Want expert advice.
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If this value is not in the database default values ​​will take 15 seconds.
Database Name: Settings.db
Field: screen_off_timeout

powerManagerServices which will take this value.
                 / / SCREEN_OFF_TIMEOUT, default to 15 seconds
                 mScreenOffTimeoutSetting = getInt (SCREEN_OFF_TIMEOUT, DEFAULT_SCREEN_OFF_TIMEOUT);
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NB will teach you a default one minute off the screen to the default never

Specifically in the frameworks / base / packages / SettingsProvider / res / valus / defaults can be found below the required fields
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Settings.db not found in the source code.
NB is really easy to use that method. Thank you!