How the reduction of Temporary Foreign Workers led to a rise in vacancy rates in South Korea
(Journal of Human Capital, Fall 2026 (vol. 20, no. 3))
This study investigates the causal relationship between the reduction of low-skilled temporary foreign workers (TFWs) and job vacancies in South Korea's manufacturing sectors, utilizing the COVID-19 quarantine policy as a natural experiment. Employing a Difference-in-Differences methodology, the research reveals that sectors with high dependence on TFWs, particularly for permanent positions, experienced significantly elevated vacancy rates for a two-year period following the onset of the pandemic. The inability of native workers to fill these positions highlights the critical role of foreign labor in mitigating labor shortages. Notably, vacancy rates began to decline only after the government relaxed quarantine restrictions, facilitating the re-entry of TFWs into the country. These findings are corroborated by local projection methods.
The Causal Effects of Tariff-Rate Quota Policies on Agricultural Product Retail Prices
with Youngmi Kim (Under Review, Agricultural Economics)
(한국어 버전: 할당관세 정책이 농산물 소매가격에 미치는 인과적 영향 (Unpublished Institutional Working Paper, Not peer-reviewed)
Tariff-Rate Quotas (TRQs) can be administered either to protect domestic industry or to promote imports aimed at alleviating supply shortages and stabilizing consumer prices. Prior empirical studies have predominantly focused on protectionist TRQs; empirical evidence regarding trade-promoting TRQs remains scarce. This paper addresses this gap by examining Korea's voluntary TRQs implemented outside WTO/FTA commitments. We estimate the causal effect on retail prices for 40 agricultural products employing Local Projection Difference-in-Differences, which exploits staggered TRQ introductions and heterogeneous tariff reduction intensities. Averaging across treated products, TRQs do not significantly alter retail prices. However, effects exhibit substantial heterogeneity: for leafy and root vegetables (Group 1), retail prices do not decline, whereas for fruits (Group 2), a 1%p reduction in the tariff rate lowers retail prices by approximately 0.9%, implying a pass-through rate of roughly 90%. Mechanism analysis reveal no significant response in import volumes for either group, thereby ruling out a import quantity channel. Tariff-exclusive import prices remain unchanged, implying that tariff-inclusive import prices decreased and suggesting approximately 100% pass-through at the import stage. Wholesale pass-through diverges between groups: characterized by low import dependence, Group 1 exhibits elevated wholesale prices, indicating that wholesalers capture the tariff reduction gains; in contrast, characterized by high import dependence, Group 2 demonstrates wholesale price declines that transmit the gains from tariff reductions entirely to the retail stage.
로봇 혁신과 인간 혁신이 노동소득분배율에 미치는 영향 (Automation, Human Task Innovation, and Labor Share)
(Under Review)
본 연구는 유럽연합 9개국을 대상으로 로봇 혁신과 인간 혁신이 노동소득분배율에 미치는 영향을 분석한다. 일반균형 모형을 통해 실증 분석을 위한 축약 회귀식을 도출하며, 2005 2019년 기간의 특허 기록과 인지 과업 지수를 활용한다. 내생성 문제를 해결하기 위해 미국 특허와 인지 과업 지수에 기반한 시프트-쉐어 도구변수를 사용한다. 분석 결과, 로봇 혁신의 증가는 노동소득분배율을 유의하게 감소시키는 것으로 나타나, 상당한 수준의 노동-로봇 대체가 존재함을 시사한다. 반면, 인간 혁신은 노동소득분배율과 양(+)의 관계를 보이나, 표본 기간 동안 인간 혁신 속도의 둔화로 인해 노동소득분배율을 오히려 감소시켰다.
(This study examines the impact of robotic and human innovation on labor share across nine European Union countries. Using a general equilibrium model, I derive a reduced-form specification for empirical analysis. The study employs patent records and a cognitive task index spanning 2005 2019. To address endogeneity concerns, I utilize shift-share instruments based on US patents and the cognitive task index. The findings reveal that increased robotic innovation significantly reduces labor share, indicating substantial labor-automation substitution. Conversely, human task innovation demonstrates a positive relationship with labor share, though slowing innovation rates during the sample period have led it to contribute to a decline in labor share.)
Work in Progress
This study proposes an innovative methodology for quantifying Routine Task Intensity (RTI) and Cognitive Task Intensity (CTI) using Large Language Models to analyze O*NET task descriptions. Employing these LLM-derived measures, we reveal a consistent decline in routine occupations across Service and Sales sectors, with Sales receiving limited attention in existing literature. Regression analysis indicates a significant upward trend in cognitive impact on wages for females, particularly in Service, Sales, and to a lesser extent, Management occupations, while routine coefficients remain stable across five decades. These results underscore the growing significance of cognitive skills, especially for women in the workforce. Despite limitations in LLM output reliability and replicability, our methodology offers a complementary perspective to existing approaches, enabling a comprehensive understanding of labor market transformations.