Aside from dictionary compilation, CJKI maintains and licenses large-scale lexical databases covering a total of approximately 24 million entries in Japanese, Chinese, Korean, and Arabic. Halpern is an avid unicyclist. In addition to being a former Guinness world record holder for fastest 100 mile run on a unicycle, he has played a major role in the spread of unicycling as a sport throughout Japan, the United States, Canada, China, and other countries. In 1978, he introduced unicycling to Japan by founding the Japan Unicycle Club (JUC), for which he served as the first chairman. Subsequently, he served as executive director of the club's successor, the Japan Unicycling Association (JUA), until 2012. His book, "Anyone Can Ride a Unicycle" (), credited as the first Japanese-language book to explain how to ride the unicycle, is still included with purchases of certain models of unicycle in Japan. In 1980, Halpern founded the International Unicycling Federation, serving as its first elected president. From 1984 until 2001, Halpern served continuously as either president and later vice president of the federation, helping to popularize competitive unicycling throughout the world. As a part of this effort, he helped to organize the first ten UNICON conferences from 1984 until 2000. In 1993, Halpern introduced competitive unicycling to China by organizing the first Great Wall Unicycle Marathon. Jack Halpern is the author of dozens of books and articles. Below is a list of selected publications: