Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar chemical composition. We initiate the Sejong Open cluster Survey (SOS) - a project dedicated to providing homogeneous photometry of a large number of open clusters in the SAAO Johnson-Cousins’ UBV I system. To achieve our main goal, we pay much attention to the observation of standard stars in order to reproduce the SAAO standard system.
Many of our targets are relatively small sparse clusters that escaped previous observations. As clusters are considered building blocks of the Galactic disk, their physical properties such as the initial mass function, the pattern of mass segregation, etc. give valuable information on the formation and evolution of the Galactic disk. The spatial distribution of young open clusters will be used to revise the local spiral arm structure of the Galaxy. In addition, the homogeneous data can also be used to test stellar evolutionary theory, especially concerning rare massive stars. In this paper we present the target selection criteria, the observational strategy for accurate photometry, and the adopted calibrations for data analysis such as color-color relations, zero-age main sequence relations, Sp - MV relations, Sp - Teff relations, Sp - color relations, and Teff - BC relations. Finally we provide some data analysis such as the determination of the reddening law, the membership selection criteria, and distance determination.

ABSTRACT
1. INTRODUCTION
2. TARGET SELECTION
    2.1 Status of Open Cluster Data
    2.2 Target Selection Criteria
3. OBSERVATION STRATEGY
    3.1 Standard Stars
    3.2 Extinction Coefficients
    3.3 Transformation Coefficients
    3.4 Time Variation of Photometric Zero Points
    3.5 Spatial Variation
    3.6 General Form of the Transformation Rela-tion
    3.7 Sequence of Observations
4. ADOPTED CALIBRATIONS
    4.1 Intrinsic Color Relations
    4.2 Zero-Age Main-Sequence Relations
    4.3 Spectral Type - Mv Relation
    4.4 Spectral Type - Temperature Relations
    4.5 Spectral Type - Color and Color - Temper-ature Relations
    4.6 Temperature - Bolometric Correction
5. DATA ANALYSIS TOOLS
    5.1 Reddening Law
    5.2 Membership Selection Criteria
    5.3 Distance
    5.4 Age and Initial Mass Function
6. SUMMARY
REFERENCES

• HWANKYUNG SUNG(Department of Astronomy and Space Science, Sejong University) Corresponding Author
• BEOMDU LIM(Department of Astronomy and Space Science, Sejong University)
• MICHAEL S. BESSELL(Research School of Astronomy and Astrophysics, Australian National University)
• JINYOUNG S. KIM(Steward Observatory, University of Arizona)
• HYEONOH HUR(Department of Astronomy and Space Science, Sejong University)
• MOO-YOUNG CHUN(Korea Astronomy and Space Science Institute)
• BYEONG-GON PARK(Korea Astronomy and Space Science Institute)