Korean materials in the Yale Library are cataloged in both Korean scripts and Romanization using ALA-LC Romanization and Word Division System, a McCune-Reischauer based standard for Korean-language materials, which is different from the official Romanization system in Korea. You will need to use correct Romanization to retrieve Korean materials in the Yale library collections.
Searching in Romanized form will bring the most comprehensive results of Korean books in both Orbis and Morris. Searching in Korean in Orbis is problematic, as books may not show up in the results even though they are available in the library. This is because of some technical problems yet to be resolved with Korean scripts in the library catalog, such as space, Romanization, etc. So if you search in Korean in Orbis, please leave no space in the string of Korean titles search (e.g. 한국교육의목표) or use proper Korean Romanization system as mentioned above.
Worldcat, a union catalog of most academic and public libraries in North America, is the most efficient and convenient tool to use if you want to search in Korean. If a book is held by the Yale University Library, Worldcat will provide a direct link to the bibliographic record in Orbis.