We present the results of BV time-series photometry of the globular cluster NGC 288. Ob- servations were carried out to search for variable stars using the Korea Microlensing Telescope Network (KMTNet) 1.6-m telescopes and a 4k pre-science CCD camera during a test observation from August to December, 2014. We found a new SX Phe star and confirmed twelve previously known variable stars in NGC 288. For the semi-regular variable star V1, we newly determined a period of 37.3 days from light curves spanning 137 days. The light-curve solution of the eclipsing binary V10 indicates that the system is probably a detached system. The pulsation properties of nine SX Phe stars were examined by applying multiple frequency analysis to their light curves. We derived a new Period-Luminosity (P-L) relation, hMV i = −2.476(±0.300) logP − 0.354(±0.385), from six SX Phe stars showing the fundamental mode. Additionally, the period ratios of three SX Phe stars that probably have a double-radial mode were investigated; PFO/PF = 0.779 for V5, PTO/PFO = 0.685 for V9, PSO/PFO = 0.811 for V11. This paper is the first contribution in a series assessing the detections and properties of variable stars in six southern globular clusters with the KMTNet system.

Abstract
1. INTRODUCTION
2. OBSERVATIONS AND DATA REDUCTION
3. VARIABLE STARS
    3.1. Semi-Regular Variable Star
    3.2. RR Lyr Stars
    3.3. Eclipsing Binary Star
    3.4. SX Phe Stars
4. SUMMARY
REFERENCES

• Dong-Joo Lee(Korea Astronomy and Space Science Institute/Department of Astronomy and Space Science, Chungbuk National University) Corresponding author
• Jae-Rim Koo(Korea Astronomy and Space Science Institute)
• Kyeongsoo Hong(Korea Astronomy and Space Science Institute)
• Seung-Lee Kim(Korea Astronomy and Space Science Institute/Astronomy and Space Science Major, Korea University of Science and Technology)
• Jae Woo Lee(Korea Astronomy and Space Science Institute/Astronomy and Space Science Major, Korea University of Science and Technology)
• Chung-Uk Lee(Korea Astronomy and Space Science Institute/Astronomy and Space Science Major, Korea University of Science and Technology)
• Young-Beom Jeon(Korea Astronomy and Space Science Institute)
• Yun-Hak Kim(Korea Astronomy and Space Science Institute/Astronomy and Space Science Major, Korea University of Science and Technology)
• Beomdu Lim(Korea Astronomy and Space Science Institute)
• Yoon-Hyun Ryu(Korea Astronomy and Space Science Institute)
• Sang-Mok Cha(Korea Astronomy and Space Science Institute/School of Space Research, Kyung Hee University)
• Yongseok Lee(Korea Astronomy and Space Science Institute/School of Space Research, Kyung Hee University)
• Dong-Jin Kim(Korea Astronomy and Space Science Institute)
• Byeong-Gon Park(Korea Astronomy and Space Science Institute/Astronomy and Space Science Major, Korea University of Science and Technology)
• Chun-Hwey Kim(Department of Astronomy and Space Science, Chungbuk National University)