Orthographic Variation in Korean

Jack Halpern
CEO
The CJK Dictionary Institute, Inc.
株式会社日中韓辭典研究所
©2001-2019 The CJK Dictionary Institute, Inc.

1. Introduction

This report provides an overview of the linguistic and orthographic issues related to the processing of Korean texts, especially webpages. It has two basic aims:

1. To enable software developers to acquire a basic knowledge of the special problems resulting from the complexity of the Korean script, especially orthographic variation.
2. To help software developers build linguistic tools for processing Korean, such as intelligent information retrieval tools, input method editors, and machine translation systems.

The Korean orthography is not as regular as most people tend to believe. Though hangul is often described as "logical" and "scientific," creating the impression that it is a highly regular, "phonetic script" (good phoneme-grapheme correspondence), in reality many phonological changes occur as a result of syllable coda (patchim) liaison , such as voicing, nasalization and resyllabification, which has a major impact on Korean TTS (text-to-speech) systems. A factor that is of crucial importance to text processing is the fact that there is a significant amount of orthographic variation.

The existence of orthographic variants and the morphological complexity of Korean pose a special challenge to the developers of linguistic tools, especially in the field of information retrieval, since the same word or phrase can be written in multiple, often unpredictable, ways. This report focuses on the major types of orthographic variation in Korean, and provides a brief analysis of the linguistic issues to be considered by software developers.

2. Hangul Variants in Loanwords

The most important type of orthographic variation in Korean is the use of variant hangul spellings in the writing of loanwords, which are very common in Korean. There are also differences in the spelling of loanwords between North Korea and South Korea (described below). Table 1 shows some orthographic variants of common loanwords from English.

Another kind of orthographic variation that plays a significant role is in the writing of non-Korean personal names, as shown in the table below.

Orthographic variation in loanwords and in non-Korean personal names is fairly common, and must be given special attention in the development of IR and translation tools.

3. Cross-Script Orthographic Variants

An important factor contributing to the complexity of the Korean writing system is the use of multiple scripts. Korean is written in a mixture of three scripts: an alphabetic syllabary called hangul, Chinese characters called hanja, and the Latin alphabet called romaja. Orthographic variation across scripts is not uncommon: the same word can be written in hangul, hangul mixed with numerals, hanja, or even English. Although the use of hanja in Korean is declining, hanja still plays a significant role in newspapers, technical journals, classical works such as the Buddhists scriptures, and proper nouns.

The table below shows the major patterns of cross-script variation in Korean.

4. North vs. South Korean Orthography

Another factor contributing to the irregularity of hangul orthography is the differences in spelling between South Korea and North Korea. This is a result of an independent language policy implemented by the North Korean government in the postwar era. The major differences are in the writing of loanwords (often influenced by Russian), a strong preference for native Korean words over loanwords, and in the writing of non-Korean proper nouns.

Typical examples are shown in the table below.

5. Miscellaneous Variants

5.1 New vs. Old Orthography

The Korean writing system went through several reforms during its history, including the invention of hangul by King Sejong in 1443, several reforms of the hangul script, and the abolishment of hanja in North Korea. The most recent reform of hangul orthography took place as recently as 1988.

Though the new orthography has now become fairly well established, the old orthography is still sufficiently common. Because the affected words are of high frequency and their number is not insignificant, they should be considered in developing linguistic tools. The table below shows typical examples.

Table 6
New vs. Old Orthography

English	As of 1988	Before 1988
Messenger	심부름군 (simbureumgun )	심부름꾼 (simburemkkun )
Worker	일군 (ilgun )	일꾼 (ilkkun )
Color	빛갈 (bitgal )	빛깔 (bitkkal )

5.2 Hanja Variants

Hanja is written in the traditional character forms. Unlike the PRC and Japan, language reforms in Korea did not include the simplification of the character forms. Thus the problem of traditional forms versus simplified ones is not a major issue. Nevertheless, the Japanese occupation of the Korean Peninsula (1910 to 1945) has had a strong influence, which resulted in many simplified Japanese character forms, including abbreviated forms, coming into common use. Typical examples are shown in the table below.

Table 7
Hanja Variants

Type of Variation	English	Standard	Variant
Variant forms	fermentation	醗酵 (balhyo )	発酵 (balhyo )
Abbreviated form	10 years old	十歳 (sipse )	十才 (sipse )
Traditional form	development	發達 (baldal )	発達 (baldal )

5.3 Miscellaneous Variants

There are various other types of orthographic variation, a detailed treatment of which is beyond the scope of this report. The table below shows the most important ones.

6. Synonym and Cross-Language Expansion

An advanced form of variant expansion is synonym expansion and cross-language expansion. The details of this are beyond the scope of this report. In a nutshell, synonym expansion generates a picklist of synonyms and other semantically related variants; cross-language expansion generates a picklist of Korean equivalents to a foreign language source term. These are shown in the table below, along with some miscellaneous variant types such as abbreviations and loanwords.

A particularly important class of synonyms in Korean is native words as opposed to those derived from other languages, especially Sinitic words and English-derived loanwords, as shown in the table below.

7. Mapping Tables and Lexical Databases

One of the central components necessary for building tools for processing Korean orthographic and other variants is a database of hard-coded mapping tables of orthographic variants and lexical databases for synonym and cross-language expansion, fine-tuned to the needs of variant expansion and normalization. Below is a list of components required for building such a database (these are currently under development at The CJK Dictionary Institute).

1. A comprehensive mapping table of hangul variants, especially in loanwords.
2. A mapping table of cross-script orthographic variants.
3. A mapping table of North vs. South Korean variants, especially in loanwords.
4. Mapping tables for miscelaneous orthographic variants, including hanja variants, old vs. new orthography, and abbreviations.
5. A dictionary of semantically classified synonym groups (Korean thesaurus).
6. An English-Korean dictionary covering general vocabulary and important proper names designed for CLIR (Cross-Language Infromation Retrieval).
7. A collection of orthographic variation rules for generating and identifying variants not listed in the database.

8. Documents for Reference

See the following links for more information:

• About the Author
• List of Publications
• The CJK Dictionary Institute