GALLERIES-CHELSEA LEE BUL This Korean artist's work often has a switchblade toughness, dark in tone and conceptually sharp. Here, shallow cases lined with two-way mirrors display what look like assault-rifle/guillotine hybrids, to vague but menacing effect. A large, chainbedecked chandelier, an homage to the architect Bruno Taut, shares a mirror-floored room with the show's centerpiece, a black "bunker" fitted with an elaborate audio system. Step inside, put on the headphones, and the gallery beyond is obliterated by amplified ambient noise; a footfall, a whisper, even a breath can sound both loud and echoingly distant. Through June 14. (Lehmann Maupin, 540 W. 26th St. 212-255-2923.)