KAT : aif.shift.func: no visible global function definition for
  ‘approxfun’
KAT : roi.modelT: no visible global function definition for ‘tail’
KAT : roi.modelT: no visible global function definition for ‘head’
KAT : roi.modelxT: no visible global function definition for ‘tail’
KAT : roi.modelxT: no visible global function definition for ‘head’
KAT : calch: no visible global function definition for ‘preplot’
KAT : calchFUNC: no visible global function definition for ‘preplot’
KAT: no visible global function definition for ‘median’
KAT: no visible global function definition for ‘write.table’
KAT: no visible global function definition for ‘optim’
KAT: no visible global function definition for ‘dev.new’
KAT: no visible global function definition for ‘plot’
KAT: no visible global function definition for ‘lines’
KAT: no visible global function definition for ‘text’
KAT: no visible global function definition for ‘quantile’
KAT: no visible global function definition for ‘graphics.off’
KAT: no visible global function definition for ‘image’
KAT: no visible global function definition for ‘palette’
KAT: no visible global function definition for ‘colorRampPalette’
KAT: no visible global function definition for ‘dev.set’
KAT: no visible global function definition for ‘locator’
KAT: no visible global function definition for ‘dev.off’
KAT: no visible global function definition for ‘pdf’
KAT: no visible global function definition for ‘layout’
KAT: no visible global function definition for ‘par’
KAT: no visible global function definition for ‘abline’
KAT: no visible global function definition for ‘points’
KAT.plot: no visible global function definition for ‘pdf’
KAT.plot: no visible global function definition for ‘layout’
KAT.plot: no visible global function definition for ‘par’
KAT.plot: no visible global function definition for ‘image’
KAT.plot: no visible global function definition for ‘palette’
KAT.plot: no visible global function definition for ‘colorRampPalette’
KAT.plot: no visible global function definition for ‘median’
KAT.plot: no visible global function definition for ‘frame’
KAT.plot: no visible global function definition for ‘plot’
KAT.plot: no visible global function definition for ‘lines’
KAT.plot: no visible global function definition for ‘text’
KAT.plot: no visible global function definition for ‘dev.off’
Undefined global functions or variables:
  abline approxfun colorRampPalette dev.new dev.off dev.set frame
  graphics.off head image layout lines locator median optim palette par
  pdf plot points preplot quantile tail text write.table
Consider adding
  importFrom("grDevices", "colorRampPalette", "dev.new", "dev.off",
             "dev.set", "graphics.off", "palette", "pdf")
  importFrom("graphics", "abline", "frame", "image", "layout", "lines",
             "locator", "par", "plot", "points", "text")
  importFrom("stats", "approxfun", "median", "optim", "preplot",
             "quantile")
  importFrom("utils", "head", "tail", "write.table")
to your NAMESPACE file.