 During this time he published and co-published several papers on the effects of photosensitive substances on glucose metabolism and cellular respiration.Returning to his native Korea, he began studies of the staple Korean diet and its effects on metabolism as a research assistant at Kyŏngsŏng Medical College in February 1928.He was appointed an instructor of physiology in the department of biochemistry of Severance Union Medical College (now Yonsei University College of Medicine) and an adjunct instructor of dietetics at Ewha Women's University College of Medicine.