## 1 Introduction  
As cultural diversity continues to grow in modern society, understanding the identity of each culture has become increasingly important. In particular, language not only functions as a means of communication but also reflects cultural identity and historical context. In Korean society, Hanja (Chinese characters) and four-character idioms (Sajaseong, [1], [2], [3], idioms strictly composed of four characters) serve as representative cultural elements that embody symbolic meaning. Over a long historical period, they have acquired distinct meanings within Korea. In fact, Hanja accounts for approximately 70% of Korean vocabulary and over 90% of technical terms, demonstrating its substantial influence on the Korean language [1, 2, 3]  
Chinese character idioms, a subset of Sino-Korean vocabulary, effectively encapsulate complex meanings or expressions in a concise form by leveraging the logographic nature of Hanja [4]. These idioms encompass both Gosaeonge ([1], [2], idioms derived from classical stories) and Sajaseonge. Among them, Sajaseonge are idiomatic expressions consisting of exactly four characters that convey the meaning of long sentences within a compact structure. This study focuses specifically on Sajaseonge. Hanja has its roots in China but has been adopted and developed differently across various Asian countries, including Korea, Japan, and Vietnam [5]. Chinese characters were first introduced to the Korean Peninsula during the late Gojoseon period, primarily in the Pyeongan region. In the regions of the Four Commanderies of Han, it is presumed that people were exposed to a relatively well-developed form of Classical Chinese [6; 7; 8]. By the Three Kingdoms period (4 th-7 th centuries), Goguryeo, Baekje, and Silla actively adopted and utilized Chinese characters [9; 10]. By the Unified Silla period (7 th-9 th century), the Idu script, a writing system that borrows the pronunciation and meaning of Chinese characters to represent the Korean language, emerged. This development marked the beginning of Korean adaptations of Hanja, where native Korean words were either written phonetically using Chinese characters or combined with borrowed Chinese vocabulary to create new words [11]. During the [PERSON] and Joseon dynasties, Hanja evolved beyond a mere writing system to become a central component of bureaucratic governance. In particular, Confucian classics formed the foundation of state education in the Joseon period, solidifying the use of Hanja vocabulary and four-character idioms as the common linguistic framework among scholars and officials. However, with the advent of modern times and the implementation of the Hangul exclusive policy, the use of Hanja gradually declined [12]. Throughout this historical transformation, certain Sino-Korean expressions have developed unique meanings and usage patterns within the Korean cultural context [13; 14]. In particular, Korean four-character idioms have evolved in various ways, such as being derived from classical Korean texts, as seen in Gyeonmunbalegom (), reacting with excessive anger over a trivial matter) and Myduhyeollyeong (, a futile discussion that cannot be put into practice), or by recombining and condensing existing Chinese idioms to create uniquely Korean expressions [15]. For instance, the idiom Hongikigan (), \"to benefit all of humanity\"), originates from Sampuk Yusa (Memorabilia of the Three Kingdoms), which documents the founding myth of [PERSON]. Another example is Hamheungchasa (), a metaphor for a situation in which no news returns after sending a message or errand. In this case, Hamheung refers to a city in present-day North Korea. Additionally, Sino-Korean synonyms, antonyms, and homophones, despite their roots in the Chinese writing system, have frequently been transformed and redefined under the influence of Korean culture [16]. These examples illustrate that both Hanja and four-character idioms serve as linguistic features that require not only linguistic knowledge but also cultural understanding and contextual interpretation.