韩国的中等强国外交在地区范围的变化和积极性变化非常明显。本论文的核心问题是韩国的中等强国外交实践中为什么会出现这样的变化。本论文通过国际关系角色理论分析框架，探索韩国中等强国外交变化的原因。根据角色理论，中等强国外交是在追求中等强国身份的情况下扮演多种国家角色的，中等强国外交的变化是由国家角色变化引起的。因此，本论文将以国家角色的变化来解释韩国中等强国外交实践中出现的积极性变化，最终目标是查明各政府的国家角色变化原因。使用角色理论分析框架的现有研究通过"国家角色"的概念，提供了统合国际结构变数和国内变数的有用的说明，但只是单纯地说明由于国家角色的变化，外交政策和外交行为出现了变化。但在本论文中将打开国家角色的黑匣子，观察外部因素和内部因素如何形成国家角色，这样的国家角色如何与外交政策和外交行为相联系。本论文将形成国家角色的内部因素和外部因素分别设定为决策者对本国的认识和对其他国家的期待的认识。因此，本论文主张，根据内部因素和外部因素的结合，各政府的国家角色得以形成，从而实践了各自的中等强国外交。本论文的假设是如此。第一，决策者具有自主的自我认识，比起依赖的自我认识，在东北亚地区将形成积极的国家作用。第二，对重要他者的认识在美国和中国双重的情况下，将形成比美国一方的认识更广阔空间的角色。本论文对象韩国的国家角色是国家决策者对本国地位的认识。因此，将把能够掌握决策者认识的演讲作为第一手数据使用。特别是总统的演讲具有代表性，会作为主要资料加以利用。此外，还将使用能够确认决策者认识的政府报告书作为辅助资料。 将对这些资料进行内容分析（content analysis）。 本论文发展了现有的角色理论分析框架，可以对韩国中等强国外交的变化提供更丰富的说明。特别是，朝核威胁和强大国家的影响力起到强烈作用的地缘政治环境，是其他中等强国不存在的韩国中等强国外交的独特环境。本论文的角色理论分析框架在一定程度上反映了这种韩国特殊环境所产生的影响力，因此具有重要意义。本论文提供韩国案例研究，在一定程度上可以为中等强国的外交研究做出贡献。
The changes in regional scope and activism are evident in middle power diplomacy of Korea. The key question of the paper is why these changes appear in the practice of middle power diplomacy of Korea. This paper explores the causes of the change with role theory analysis framework. According to role theory, middle power diplomacy is to perform several national role conceptions for seeking status of middle power. Based on role theory analysis, first, this paper interprets the changes of middle power diplomacy of Korea as the change of national role conceptions. Then, the ultimate goal of this study is to identify the causes of the changes in the role conceptions of each government. Existing researches that had analyzed middle power diplomacy of Korea through the role theory analysis framework provided useful explanations by integrating international and domestic variables through the concept of national role conception. However, the time range of existing researches was limited to Roh Moo-hyun and Lee Myung-bak administrations, so it was only a comparison between governments. This paper expands the time range of research to explore the causes of changes in Korea's national role conceptions.This paper established self-expectation and internalized expectations of the other states as ego-part and alter-part, respectively, which form national role conceptions. The two pillars that form national role conceptions are the policy maker's perception. This is the hypothesis of this paper. First, if policy makers have independent self-identification, they will form a leading state role in Northeast Asia rather than having dependent self-identification. Second, if the perception about important other is divided into two sides of the U.S. and China, it will form a role that emphasizes coalition rather than recognizing the U.S. as important other. The research subjects of this paper are the national role conceptions of each government from Roh Moo-hyun to Moon Jae-in. Therefore, this paper uses speeches of policy makers that demonstrate the national role conceptions as primary sources. In particular, the president's speech is used as the main material. In addition, government reports shall be used as supplementary data. And then, this paper conducts a content analysis of these data.This paper develops the existing role theory framework and provides compelling explanations for changes in Korea's middle power diplomacy. In particular, such geopolitical conditions as inter-Korean military confrontation, North Korea's nuclear threat, and conflict between the continent and maritime forces are unique environments for South Korea's middle power diplomacy that do not exist in other middle power countries. The analysis framework of this paper can reflect to some extent the impact of this unique environment of Korea. In addition, this paper can contribute to the study of middle power diplomacy by providing Korean case studies.
