This year, for the first time in its 22-year history, South Korea's Yulchon will not be led by one of its six founders. Lawyers who specialise in corporate law and disputes have been added to the firm's management as it seeks to break out from its traditional strength in tax and antitrust.

The new managing partners – Kang Seok-hoon, Yoon Yong-sup and Yoon Hee-woong – took over on February 1 from Yun Sai-ree, Yulchon's managing partner of seven years and a prominent antitrust and tax lawyer in Korea. Yun was the firm's second managing partner after succeeding Woo Chang-rok, also a founder and tax specialist, in 2012.

Founded in 1997, Yulchon is the youngest of Korea's Big Six – the largest six law firms by number of lawyers in the country. The other five were founded in the 1970s and '80s. The firm started with only 10 lawyers and grew more than 30-fold in about 20 years. In the 2017 Asia 50 survey, Yulchon reported 368 lawyers.

The new leadership wants to keep the growth going. "We hope to become a top three firm [by headcount] within three years," said Yoon Hee-woong, adding that the growth needs to be profitable as well.

According to the latest Asia 50 survey, Yulchon is the fifth-largest Korean firm by headcount,  thanks to a single additional lawyer. (Yoon & Yang, the smallest of the Big Six, reported 367 lawyers in 2017.) Yulchon will need to accelerate growth to catch up to Lee & Ko, the third-largest Korean firm in 2017, with 616 lawyers. Kim & Chang, the country's biggest, had 920 lawyers and was followed by Bae, Kim & Lee with 625 lawyers in 2017.

Yun's tenure at Yulchon saw the firm not just grow in size, but also into one of Korea's premium domestic firms, especially for antitrust and tax practices. Over the years, the firm advised U.S. airline Delta Air Lines on competition law matters on a metal-neutral joint venture with Korean flag carrier Korean Air – the first of its kind in Korea. (Metal neutrality refers to a joint venture in which the airlines involved share revenue and costs on a given route no matter which is doing the actual flying.) Yulchon also advised Korea's Daewoo Shipbuilding & Marine Engineering on the tax aspects of a $1.35 billion debt restructuring.

And under Yun's leadership, Yulchon continued its international expansion overseas. In 2014, the firm was the first of the Big Six to launch in Myanmar, with an office in Yangon (the only other Big Six firm in the southeast Asian country so far is Bae, Kim & Lee, which opened in 2016). Yulchon also was the first Korean firm to enter Russia, with an outpost in Moscow in 2015 – still the only one among its peers to do so.

Yun retired from Yulchon's partnership after he turned 65 years old – the firm's retirement age – last November. He will stay with the firm as "honorary managing partner" and lead corporate social responsibility initiatives.

The change in leadership is occurring as the firm strives to branch out beyond its strength in tax and antitrust law. It wants to expand its practices in corporate law and disputes.

Kang and Yoon Yong-sup are former judges, specialising in tax and civil disputes, respectively. Yoon Hee-woong was the head of the firm's corporate and finance group, focusing on mergers and acquisitions. He joined Yulchon in 2001 from legacy Yoon & Partners (now the leading Korean firm Yoon & Yang). In 2015, he advised Korean conglomerate Hanwha Group on a $935 million acquisition of Samsung General Chemicals Co. Ltd. from Samsung C&T Corp.

"Yulchon is famous for tax," Yoon Hee-woong said. "Of course, we will continue to grow our strength [in tax], but at the same time, we will grow other practice areas, too, such as corporate and finance, mergers and acquisitions, private equity, data privacy, and pharmaceuticals. Our focus reflects the Korean companies' interest and demands."

Pharmaceuticals, in particular, are a high priority for Korea – the world's fastest-ageing country. Samsung Group, the country's largest conglomerate, named biopharmaceuticals as one of its five new growth engines in 2010, alongside medical equipment, solar batteries, electric-vehicle batteries and light-emitting diodes, and pledged to invest about $20 billion into the five areas by 2020.

Yulchon is also building a track record in pharmaceuticals. Last year, the firm successfully helped Samsung Bioepis Co. Ltd., part of the biopharmaceutical business of Samsung Group, settle a patent dispute with U.S. drugmaker AbbVie Inc., allowing Samsung Bioepis to commercialise a biosimilar version of AbbVie's arthritis treatment Humira.

Yulchon's growth plan to be one of the three largest firms in Korea is largely focused on domestic expansion, as the firm does not have immediate plans to add to its six international offices.

"We see a competitive edge in opening offices in markets that don't have a large presence from Western or foreign law firms, like Russia and southeast Asia," Yoon Hee-woong said.

Yulchon is one of the more international Korean firms and was the first major Korean firm to enter Vietnam in 2007, via Ho Chi Minh City – a market the rest of the Big Six entered only in the past few years. The firm also has another office in Vietnam, in Hanoi. And in addition to its offices in Yangon and Moscow, it has an office in Shanghai, which is considered China's financial capital.

But in regions where there are international firms, "we prefer to cooperative with those firms instead of opening our own office", he said.

"We are always considering," Yoon said, "but we have to consider very prudently."