There are many configuration methods, different scim versions and libraries. I am not quite sure why this method is necessary on my RHEL 5.3.
execute the skype with the following command, After that, scim panel starts to respond when I execute the skype.
export XMODIFIERS="@im=SCIM"
export GTK_IM_MODULE="scim"
export QT_IM_MODULE="scim"
scim -d
/DefaultIMEngineFactory/en_US = d75857a5-4148-4745-89e2-1da7ddaf70a9
/FrontEnd/ChangeFactoryGlobally = false
/FrontEnd/OnTheSpot = true
/FrontEnd/SharedInputMethod = false
/FrontEnd/Socket/ConfigReadOnly = false
/FrontEnd/Socket/MaxClients = 512
/FrontEnd/X11/BrokenWchar = true
/FrontEnd/X11/Dynamic = false
/FrontEnd/X11/OnTheSpot = true
/FrontEnd/X11/ServerName = SCIM
/Hotkeys/FrontEnd/NextFactory = Control+Alt+Down,Shift+Control+KeyRelease+Shift_L,Shift+Control+KeyRelease+Shift_R
/Hotkeys/FrontEnd/Off =
/Hotkeys/FrontEnd/On =
/Hotkeys/FrontEnd/PreviousFactory = Control+Alt+Up,Shift+Control+KeyRelease+Control_L,Shift+Control+KeyRelease+Control_R
/Hotkeys/FrontEnd/ShowFactoryMenu = Control+Alt+Right
/Hotkeys/FrontEnd/Trigger = Hangul,Shift+space
/Hotkeys/FrontEnd/ValidKeyMask = Shift+Control+Alt+CapsLock+Meta+QuirkKanaRo
/IMEngine/Hangul/CommitByWord = false
/IMEngine/Hangul/HangulKey = Hangul,Shift+space
/IMEngine/Hangul/HanjaKey = Hangul_Hanja,F9
/IMEngine/Hangul/HanjaMode = false
/IMEngine/Hangul/HanjaModeKey =
/IMEngine/Hangul/KeyboardLayout = 2
/IMEngine/Hangul/ShowCandidateComment = false
/IMEngine/Hangul/UseAsciiMode = false
/IMEngine/RawCode/Locales = default
/Panel/Gtk/Color/ActiveBackground = light sky blue
/Panel/Gtk/Color/ActiveText = black
/Panel/Gtk/Color/NormalBackground = #F7F3F7
/Panel/Gtk/Color/NormalText = black
/Panel/Gtk/DefaultSticked = false
/Panel/Gtk/Font = UnGungseo 12
/Panel/Gtk/LookupTableEmbedded = false
/Panel/Gtk/LookupTableVertical = false
/Panel/Gtk/ShowStatusBox = false
/Panel/Gtk/ShowTrayIcon = false
/Panel/Gtk/ToolBar/AlwaysHidden = false
/Panel/Gtk/ToolBar/AlwaysShow = false
/Panel/Gtk/ToolBar/AutoSnap = false
/Panel/Gtk/ToolBar/HideTimeout = 2
/Panel/Gtk/ToolBar/POS_X = 1184
/Panel/Gtk/ToolBar/POS_Y = 739
/Panel/Gtk/ToolBar/ShowFactoryIcon = false
/Panel/Gtk/ToolBar/ShowFactoryName = false
/Panel/Gtk/ToolBar/ShowHelpIcon = false
/Panel/Gtk/ToolBar/ShowMenuIcon = false
/Panel/Gtk/ToolBar/ShowPropertyLabel = false
/Panel/Gtk/ToolBar/ShowSetupIcon = true
/Panel/Gtk/ToolBar/ShowStickIcon = false
/UpdateTimeStamp = 1247044282:329136