I studied at Seoul National University and lived in Seoul from 2005 to 2010, where I had lots of opportunities to learn what South Koreans thought about themselves and their relationship with their old neighbor- China.
Some South Koreans feel good that their country is homogeneous national state, including one of my dear professors who sometimes mentions this with proud smiles during his lectures about South Korean economic achievements in front of a group of international students. Obviously, they see a homogeneous national state as generally helpful to South Korea’s development. Yes, I agree the achievements that South Koreans made are partially attributed to the single nationality. It is hard to criticize their sentiments toward their own people, and nation.
However, it can become a fence between Korean nationals and others, a poisonous wine, killing the willingness to approach other nationals from a sincere heart. They shut their doors to the outside, which may be the reason some have Sinophobia. Although South Koreans always pursue an export-oriented economy, their ideology is quite a different thing.
Koreans have a negative impression of China in terms of the lower quality of cheap products, human smuggling and illegal workers in South Korea, all of which may compete for Korean products and labor forces at home and abroad, legally or illegally.
On the other hand, some Koreans are all smiles when they meet with a Westerner, which does not mean they like them. They just don’t know how to start to talk to strangers due to their different appearances and cultures. In the deepest part of their hearts, it may be the sense of inferiority that results in prejudice when they face different nationals, such as Americans or Chinese.
A trend I noticed during my five years in South Korea was that the higher the social status, the friendlier they are with Chinese; the more Koreans know about China, the less bias they’ll have.