To the person who asked about the conditions for an expat assignment in Irvine

Based on my experience living in LA for several years,
1. Economic Conditions
If we assume a pre-tax salary of 220 million KRW including living expenses, which is roughly 150 million KRW after tax (about 13 million KRW per month),
Housing Rent: For a decent house in Irvine suitable for a family of four, rent will be at least $4,000–$5,000 per month.
Food and Shopping (clothing, household goods, etc.): Since prices in the US have skyrocketed, you will need at least $1,500 to enjoy a lifestyle similar to Korea (this is based on not eating out frequently).
Utilities: Electricity, water, gas, internet, mobile phone, trash collection, etc., will cost at least $700 per month (based on a single-family house).
Car Insurance: If operating two vehicles (two cars are almost essential for things like picking up kids from school), it will cost at least $300–$400.
Health Insurance: Usually, the company provides this, but since they said living expenses are bundled into the total amount, there likely won't be separate support. In that case, even with minimum coverage, a family of four will spend around $1,000 per month.
When you add fuel costs and various incidental expenses, your salary will barely cover the cost of living.
Additionally, more money is spent than expected on the process of moving to the US, adjusting, and eventually returning to Korea.
2. Children's Education
In Irvine, even the public schools up to middle school are at a good level.
However, unless you plan to leave your children in the US to attend university, there isn't much significant benefit to spending 2–3 years in the US.
The English studied for Korean university entrance exams will require them to attend academies again once they return to Korea.
In fact, you should provide tutoring aligned with the Korean curriculum to prepare for their return to Korea.
If you hire a Korean tutor or enroll them in online lectures from Korean academies, you will spend at least 1 million KRW per month per child.
Conclusion: Unless you place a high value on the experience of living in the US once, it's probably not worth it.