History of the Korean writing system

Koreans use their own unique alphabet with letters for every sound of speech. It was not always like this. In the past Koreans did not have their own letters and they had to adopt Chinese characters though the languages in Korea and China are totally different from any side. Writing with Chinese characters in Korea was called hanmun that means Han writing, from Han Dynasty in China. To read a Korean text written in hanmun one should know old Chinese written language. 

Koreans used Chinese characters to write down Korean words and grammatical meanings. Then they invented a number of characters of their own combining two Chinese symbols into one. 

New system of adaptation for Chinese writing in Korea was knows as idu (ridu in North Korean pronunciation). Using it, Koreans started experimenting with separated elements of Chinese characters trying to express sounds for reading Korean names. For example, word stone sounds as dol (돌) in Korean and shi in Chinese for hieroglyph 石 with the same meaning. To write down not only the meaning but also pronunciation, Koreans combined this hieroglyph with sign 乙 that has a Korean reading as ul. This way they have got a combination of two Chinese elements, one for the meaning and another with a hint on its pronunciation.

 

System of writing idu went through transformation in time with a number of efforts to adopt Chinese characters to Korean language. Let's have a look at the text engraved on "sacred stone" in early idu script:

任申六月十六日二人并誓記 天前誓今自三年以後忠道執持過失无誓若此事失天大罪得誓若國大安大乱世可盛行誓之又別生辛未年七月廿二日大誓

Translation: “on the year of Imsin 16th day of the 6th moon two persons (二人) together (并) have sworn  (誓) oath, that is documented by this record (記). We swear for three years not to make a balk going by the path of allegiance. If (若) failed (此事失), we swear to accept judgment (大罪得). We swear to seek peace and tranquility in the world (可盛) wether there will be chaos or order. Separately, an oath was sworn first (先) on the year of Sinmi (辛未), on the the 22nd day of the 7th moon.

As we can see, in this text sentence structure differs from Chinese as the predicate was placed at the end. That is why it was easy to read the text in Korean deciphering the meanings of the Chinese characters. 

One more example, a record on a stone stella in Kalhan-sa temple, will illustrate the system more:

二塔天宝十七年戊戌中立在之娚姉妹三人業以成在之.

Translation: “Two pagodas (二塔) is being erected (立在之) on the 17th year of Chonbo (天宝). The work is done by three people - elder brother, elder sister and younger sister (娚姉妹)”.

For expressing grammatical meanings following elements are used: 中 – «in»; 以 – ablative case, 在 – honorific suffix (of politeness).

Idu developed in to another writing system called ichal that used even more particles and suffixes to make records as close to speech as possible. Then a new system hyangchal came that made possible even to write down poems hyangga in Korean. 

紫布岩乎邊希執音乎手母牛放敎遣吾肹不喩慚肹伊賜等花肹折叱可獻乎理音如

 In old Korean the reading is as follows.

Modern Korean:

Peulgeun baho ka-e

Jabamoson omiso nohagyosigo

Naheul andi bukkeurisyadon

Gocheul geotko batchahorimnida.

Translation: 

On the Red Clif

Put a caught bull

If you won't give me sorrow 

I will gather flowers for you. 

There was the following case markers in hyangchal writing system:

Nominative - 亦/ 是 (民是 [min-ee] «people»)
Topic - 隱/焉 (吾焉 [na-neun] «I» "Me")
Accusative - 肹/乙 [-heul/-eul]
Genitive - 矣/衣 [-eui]
Instrumental - 以/留 (筆留 [pus-euro] «by drawing brush»)
Locative - 中 [-eseo] 
Cominative - 果 [-kwa]
Vocative - 下/ 也 [-ha/-a]

In Koryo Kingdom of 12 century writing words became more complex. A word should be written first with Chinese characters showing the word's meaning followed by another Chinese characters showing the pronunciation. The two parts of the word were divided by another Chinese character with the meaning "to say". The whole word structure looked like "write this way and speak this way". 

足曰發 (발) – foot
火曰孛 (불) – fire
水曰没 (물) – water
雲曰屈林 (구름) – cloud
高曰那奔 (높은) – high

By the 14th century it the Korean writing system certain number of characters for suffixes and case markers were established. For convenience the characters were simplified so that they could not be mixed with hieroglyphs with lexical but not grammatical meaning (see examples on the right).

Koreans obviously realized as imperfect the way they had to adopt a foreign script for their own language. They have tried other language systems including Tibetan and Brahmi, Kidan, Jurchen and Tangut. Nothing could serve Korean language perfectly among them.  

In 15th century the fourth King of Lee Dinasty by the name Sejong the Great took the throne in Korea. Reforms had beeb started, education and strengthening of the statehood were in the center of attention by the King. A new period known as the "golden age" of the Korean culture has began.   At that time national writing system was created to the people in the Kingdom. The Korean alphabet was introduced in 1446 by the King's edict Hunmin Chongum (The Correct Sounds for the Instruction of the People).   

Introducing the edict, King Sejon wrote: "Sounds of speech in our country, unlike China, do not match properly the symbols for their expression. That is why there are many among untaught people that would like to write down something but can not express thoughts. Looking at this with sorrow, I have reated twenty eight new letters. I wish everybody could easily learn them and use it every day".
For consonants, a number of symbols were invented to graphically copy elements of articulation organs. For example, dental sound [s] has a symbol in the shape of a tooth ㅅ, and [ch/j] looks like a tooth with occlusion ㅈ. The sound [k] is pictured in form of a tongue bent to palate. The sound [n] contrary reflects the form of a tongue with its end up to teeth ㄴ, and [t] shows how a tongue with occlusion ㄷ. The symbol for sound [m] repeats the form of lips while pronouncing it ㅁ, and the sound [p] pictures occluding lips ㅂ. 
Nasal sound [ng] is written as a circle because of the form of throat ㅇ. 
The guttural [h] matches a letter repeating the shape of a throat occluding with palate ㅎ. Sounds [l/r] have a letter in the form of curved tongue ㄹ, but more resembles Chinese symbol 乙 from the idu writing system.
Aspirate consonants are written by symbols with extra line to show that the sounds should be pronounced with more force:

ㄱ [k] - ㅋ [k']
ㄷ [t] – ㅌ [t']
ㅂ [p] – ㅍ [p']
ㅈ [ch/j] – ㅊ [ch']

Strong and double consonants have double writing. 
ㄱ [k] – ㄲ [kk]
ㄷ [t] – ㄸ [tt]
ㅂ [p] – ㅃ [pp]
ㅅ [s] – ㅆ [ss]
ㅈ [ch] – ㅉ [jj]

The edict "Hunmin jongum" introduced some extra symbols for consonants that are out of use anymore. 
Vowel letters were invented using Chinese philosophy of creation. I would not explain this complicated theory but just list the symbols for vowels. 

ㅏ [a]       ㅑ [ya] 
ㅓ [ô]       ㅕ global [yô]
ㅗ [о]       ㅛ [yo]
ㅜ [u]       ㅠ [yu]
ㅡ [eu]
ㅣ [i]         ㅢ [eui]
ㅐ [ae]      ㅒ [yae]
ㅔ [e]        ㅖ [ye]
ㅚ [oе]      ㅙ [вэ]
ㅞ [ue]      ㅘ [wa]

This is how Koreans got their national phonetic writing system, which, unlike European languages, was designed do record not single sounds but whole syllables. If a syllable starts with a vowel, first a circle ㅇ should be written, what in this case means not nasal consonant  [ng], but the "zero" and it could not be read. If  is followed by a vowel with vertical line, "zero" is written on the left. But and if the vowel has a horizontal line, then the "zero" letter is on top. Same system works with placing initial consonants in syllables. For example:

아 [a] 안 [an] 온 [on] 육[yuk] 웨 [we]
나 [na] 간 [kan] 돈[ton] 줄[chul] 황 [hwang]

Wnen the national alphabet emerged in Korea, it caused resistance of conservatives, largely because the country was still a vassal state of China. Korean letters then was used to record the endings and suffixes together with words written with Chinese hieroglyphs. The mixed writing system functioned to the end of the 90s in South Korea. At the same time, North Korea has refused to use hieroglyphics any more in the 60s on the wave of the reform of education and the language. It helped to achieve 100 percent literacy in the country. South Korea did the same but much later but still a limited number of hieroglyphics, more than 2000 in total, are taught at schools so that people can understand at least the meaning of their names and surnames. In Korea, the majority of names have hieroglyphic origins. 
National alphabet in North Korea is called kunmun ("national writing"), and hangul in South Korea that means "writing of the Han country".

Sources:  김영황 "조선민족어 발전력사 연구" (평양 1978); "Хунмин чоным" (Исследование, перевод с ханмуна, примечания и приложения Л.Р.Концевича, Москва 1979)