  We have carried out high resolution observations with Atacama Large
Millimeter/Submillimeter Array (ALMA) of continuum emission from Orion KL
region. We identify 11 compact sources at ALMA band 6 (245 GHz) and band 7 (339
GHz), including Hot Core, Compact Ridge, SMA1, IRc4, IRc7, and a radio source I
(Source I). Spectral energy distribution (SED) of each source is determined by
using previous 3 mm continuum emission data. Physical properties such as size,
mass, hydrogen number density and column density are discussed based on the
dust graybody SED. Among 11 identified sources, Source I, a massive protostar
candidate, is a dominant energy source in Orion KL. We extensively investigate
its SED from centimeter to submillimeter wavelengths. The SED of Source I can
be fitted with a single power-law index of 1.97 suggesting an optically thick
emission. We employ the H$^{-}$ free-free emission as an opacity source of this
optically thick emission. The temperature, density, and mass of the
circumstellar disk associated with Source I are constrained by the SED of
H$^{-}$ free-free emission. Still the fitting result shows a significant
deviation from the observed flux densities. Combined with the thermal dust
graybody SED to explain excess emission at higher frequency, a smaller
power-law index of 1.60 for the H$^{-}$ free-free emission is obtained in the
SED fitting. The power-law index smaller than 2 would suggest a compact source
size or a clumpy structure unresolved with the present study. Future higher
resolution observations with ALMA are essential to reveal more detailed spatial
structure and physical properties of Source I.
