"Early" here refers to the early post-war periods of both countries respectively.
I was thinking about Chinese manufacturing industry, which rose to prominence in the 2000s but has garnered a reputation for often being shoddy and second-rate. It could be argued that this is because the manufacturing industry in China is still in a nascent phase due to gaps in technology and development in general. What were similar industries and companies in Japan and Korea like when they were beginning to establish themselves globally in the mid to late 20th century?
EDIT: I hope that second paragraph doesn't break the 20-year rule - the part with China isn't a part of my question and was just looking at the situation from a point of view.
Japanese products - no. Korean products - yes.
Japan began modernizing after the Meiji Restoration in 1868 and had become an industrialized nation by the early 20th century. From 1894 to 1910, Korea attempted to modernize while Japan was slowly absorbing Korea into it's empire. From 1910 until 1945, Korea was a colony of Japan and the Japanese modernized the country. Railroads, massive industrial complexes, and one of the most advanced hydroelectric power systems in the world were all built in Korea using Japanese knowledge and technology. Most of the industrial capability was put in North Korea since they had the mountains for the dams and raw materials for the factories while South Korea got lots of agricultural knowledge.
Once World War 2 ended, the Japanese left and Korea was left with a great system but nobody to run it since the managers and supervisors were all Japanese. The workforce in Japan was educated and had nearly 80 years of industrial research and growth behind them while the workforce in Korea was made up of workers with little education behind them. Then during the Korean War, North Korean industry was decimated by the UN forces and the entire Korean peninsula was destroyed. It wouldn't be until Park Chung-hee and his cabal took over in 1961 that industrial output became a real focus of the government. In 1965, Korea signed a treaty with Japan to establish relations. As part of the deal, Japan gave some 800 million dollars in cash, loans, and technology transfers as reparations for the colonial era. The Korean government used that money to build POSCO, the Pohang Steel Company, and the Guro Light Industrial complex. They also supported the chaebols, especially Hyundai, through lucrative government contracts.
Korea produced light manufactured products - consumer electronics and clothing being the big ones - and they were of mediocre quality. The large chaebols made everything, Daewoo being a good example. In the 80's Daewoo made consumer appliances, cars, and weapons for the military, as well as doing domestic construction. Hyundai was building highways in Vietnam which is where Lee Myung-bak, former popular Mayor of Seoul and unpopular President of Korea, got his start. The quality was mediocre for a few reasons. First, the companies were new and they didn't have a lot of experience. Second, they were willing to trade quality for price. Korea was still a relatively poor country - the GDP per capita didn't break 20k USD, the level at which a country is considered developed, until 2008, and then the recession knocked it down, and they didn't surpass it and stay above it until around 2010. If they spent more money to make better quality products, Koreans wouldn't be able to buy them. Finally, Korea had to compete against Japan in the world market. In the 80's, all the best stuff was made in Japan and there was no way that Korea could compete in quality so they had to compete in quantity.
The big change came with Lee Kun-hee in 1993. Lee was the oldest son of Lee Byung-chul, the founder of Samsung, and he became the chairman of Samsung in 1987 after his father died. In 1993, he told his employees to "change everything except your wife and children". He decided that Samsung was going to compete on quality and he spent the next 20 years changing the culture of Samsung into what it is today. In 1994, Samsung Motors was founded and partnered with Nissan to make the SM series of cars. Without getting into the details, it was during the 90's that Samsung, Kia, and Hyundai all overhauled their plans and worked on changing their images. Goldstar became LG in 1994. They bought Zenith and they developed supply connections with US companies. It's not a coincidence that this all happened around the same time - Samsung makes up a full 10% of the Korean economy. Lee's decision to change Samsung pushed everyone to change. Also, the 1998 financial crisis forced companies to streamline. It was the crisis that caused KIA to go bankrupt and resulted in the merger with Hyundai.
In regards to China, it's the same thing. China was poor and they had no technical knowledge but plenty of cheap labor. They began making clothes and other small, simple devices (which Korea used to make) and began to compete using quantity instead of quality. Taiwan did it, Bangladesh, India, Pakistan... it's the stepping stone to building a more advanced economy. China's been making cheap toys for decades, and it's only in the last 10-15 years that they've really started showing promise with televisions, phones, and other consumer electronics. Huawei has been making some great smartphones that can compete with LG and Samsung on quality and price, an idea that would have been laughed at not even ten years ago.
TLDR - Japanese manufacturers had been working for a solid 80 years before Korean manufacturers. Korea competed against the Japanese on the world market on quantity instead of quality until the 90's when Samsung and the financial crisis caused everyone to change their attitudes. China today is Korea 20 years ago and Korea today is Japan 20 years ago.