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tokens: The expanding H ii region may overrun and compress these nearby preexisting clumps/cores, causing them to collapse and form new stars/clusters. This is the so-called radiation-driven implosion model (Bisbas et al. 2009 ). As the ionization front “boiled off” the outer parts of those dense clumps/cores, the rest of the neutral gas is stretched out into a cometary globule, with a dense head surrounding the newly formed stars, a bright rim pointing toward the ionizing star, and a cometary tail pointing away from the ionizing star (Bisbas et al. 2011 ). Appearances of cometary globules and bright-rimmed clouds inside H ii region are thought to be the evidence of the radiation-driven implosion model (Bisbas et al. 2011 and references therein). Considering that expanding bubbles interact with surrounding materials and trigger star formation, it is reasonable to expect that bubbles of larger size will have much more time to sweep around the surrounding materials, and thus have more chances to trigger star formation and then show more evidence of triggered star formation (Yuan et al. 2014 ), and vice versa for bubbles with smaller size. Hence we plan to study the molecular cloud and star formation around bubbles with larger and smaller sizes separately in a large sample, compare them with each other, and get evidence of triggered star formation. We found a sample of 226 bubbles from the catalog of Simpson et al. ( 2012 ) in the region covered by the 12 CO(3–2) survey performed with the James Clerk Maxwell Telescope (JCMT) submillimeter telescope (Dempsey et al. 2013 ). The 12 CO(3–2) data makes it possible for us to study the molecular gas around these bubbles in a relatively high angular resolution. As a pilot study, we first investigate G15.684-0.29 as one example of the largest bubbles in our sample, and G13.899-0.011 as one example of the smallest bubbles in our sample in the next paper. G15.684-0.29, which has a diameter of 31.4 pc (Section 3 ), is an ideal bubble for studying triggered star formation. Similar to RCW 79 and RCW 120 (Zavagno et al. 2006 , 2007 ), G15.684-0.29 has a simple morphology (circular ionized regions surrounded by dust emission rings in the mid-IR) and hosts signposts of massive-star formation at their peripheries (luminous IR sources, ultracompact radio sources; Section 3 ). Near-IR imaging gives information about the stellar nature of the luminous IR point sources observed at the borders of the ionized regions. In this work, we study the large bubble G015.684-0.29, and see if it is easy for the large bubble to trigger star formation. We describe our data in Section 2 and give a simple introduction of G15.684-0.29 in Section 3 . We present the results and discussions in Section 4 and a summary in Section 5 . 2. Archival Data 2.1. The GLIMPSE and MIPS Survey The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) is a mid-infrared survey (3.6, 4.5, 5.8, and 8.0 μ m) of the Inner Galaxy performed