Codeigniter TimeZone タイムゾーン関連の問題と PHP タイムゾーン設定

[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
date.timezone = PRC

{ "cst",   0,  28800, "Asia/Chongqing"                },
{ "cst",   0,  28800, "Asia/Chungking"                },
{ "cst",   0,  28800, "Asia/Harbin"                   },
{ "cst",   0,  28800, "Asia/Kashgar"                  },
{ "cst",   0,  28800, "Asia/Macao"                    },
{ "cst",   0,  28800, "Asia/Macau"                    },
{ "cst",   0,  28800, "Asia/Shanghai"                 },
{ "cst",   0,  28800, "Asia/Taipei"                   },
{ "cst",   0,  28800, "Asia/Urumqi"                   },
{ "cst",   0,  28800, "PRC"                           },
{ "cst",   0,  28800, "ROC"                           },

<?php 

date_default_timezone_set('America/Los_Angeles');