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특별기고 : 동국정운(東國正韻)은 정당(正當)하게 평가(評價)되어야 한다
정연찬 ( Yun Chan Chung ) 서강대학교 언어정보연구소 2015 언어와 정보 사회 Vol.24 No.-
This paper contends that Donggukjeongun was a pronunciation dictionary of Sino-Korean characters in Middle Korean by King Sejong. King Sejong realized that many Sino-Korean words had a incorrect pronunciation, so he tried to establish standard pronunciations of them after collecting and assessing all the pronunciations and phonological characteristics of Sino-Korean characters. He tried to underscore the autonomy of the pronunciations as Donggukjeongun is a unique Korean way of rending Chinese characters. Donggukjeongun is difficult to identify as 운서 (韻書, rhyme dictionary, i.e., books classifying Chinese characters depending on the phonological properties) because it contains little exegesis. Further it does not follow the organization of 운도 (韻圖, rhyme table, i.e., chart showing the place of articulation and aperture along with illustrations). Therefore, Donggukjeongun is identified as a pronunciation dictionary.
정연찬(YunChan Chung),장민호(Minho Chang) (사)한국CDE학회 2009 한국CDE학회 논문집 Vol.14 No.1
Triangular mesh models are widely used in reverse engineering, computer graphics, rapid prototyping and NC (numerical controller) tool-path generation. Triangular mesh models are generated from point clouds, surface models and solid models. A halfedge-based triangular mesh data structure is proposed and the development considerations are presented. In the presented data structure, halfedge is the key data structure. Halfedge stores its triangle index and the order in the triangle. Triangles do not store the halfedge lists explicitly. Halfedge is referred by value and defined when it is required. Proposed data structure supports four design requirements: efficient rendering, compact memory, supporting efficient algorithms and easy programming.
정연찬(YunChan Chung) (사)한국CDE학회 2012 한국CDE학회 논문집 Vol.17 No.3
This paper presents an overview of automated robotic system for skull drilling, which is performed to access for some neurosurgical interventions, such as brain tumor resection. Currently surgeons use automatic-releasing cranial perforators. The drilling procedure must be performed very carefully to avoid penetration of brain nerve structures; however failure cases are reported. The presented prototype system utilizes both preoperative and intraoperative information. Preoperative CT image is used for robot path planning. A NeuroMate robot with a six-DOF force sensor at the end effector is used for intraoperative operation. Intraoperative cutting force from the force sensor is the key information to revise an initial registration and preoperative path plans. Some possibilities are verified by path simulation but cadaver experiments are required for validation of this prototype.
측정 데이터 이용한 자동차 외판 미세굴곡 추적 사례 연구
정연찬(Yun Chan Chung),이상헌(Sang Heon Lee),장대순(Dae Soon Chang),박상철(Sang Chul Park) (사)한국CDE학회 2013 한국CDE학회 논문집 Vol.18 No.2
This paper proposes an approach to detect unintended deflections in an automotive outer panel. Conventionally, the detection of unintended deflections has been performed by experienced works, and it requires much amount of time and efforts. The motivation of this work is to reduce such efforts by providing an automated detection methodology. For the detection of unintended deflections, we make use of the measured data from an optical scanner which can be considered as a Z-map data. The proposed approach consists of four major steps; 1) measured data acquisition for an automotive outer panel, 2) identification of shape features, 3) removal of shape features, and 4) detection of unintended deflections via curvature analysis.
정연찬(YunChan Chung) (사)한국CDE학회 2013 한국CDE학회 논문집 Vol.18 No.4
This paper presents a tool-path generation methods for an automated robotic system for skull drilling, which is performed to access to some neurosurgical interventions. The path controls of the robotic system are classified as move, probe, cut, and poke motions. The four motions are the basic motion elements of the tool-paths to make a hole on a skull. Probing, rough cutting and fine cutting paths are generated for skull drilling. For the rough cutting path circular paths are projected on the offset surfaces of the outer top and the inner bottom surfaces of the skull. The projected paths become the paths on the top and bottom layers of the rough cutting paths. The two projected paths are blended for the paths on the other layers. Syntax of the motion commands for a file format is also suggested for the tool-paths. Implementation and simulation results show that the possibility of the proposed methods.
삼각망 곡면의 3축 라운드엔드밀 가공을 위한 공구경로 생성
정연찬(YunChan CHUNG) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.2
Presented in this paper is a method to generate round-endmill toolpaths for sculptured surfaces represented as a triangular mesh model. The proposed method is applicable in toolpath generation for ball-endmills and flat-endmills because the round-endmill is a generalized tool in three-axis NC (numerical control) milling. The method uses a wire frame model as the offset model that represents a cutter location surface. Since wireframe models are relatively simple and fast to calculate, the proposed method can process large models and keep high precision. Intersection points with the wireframe offset model and a tool guide plane are calculated, and intersection curves are constructed by tracing the intersection points. The final step of the method is extracting regular curves from the intersection curves including degenerate and self-intersected segments. The proposed method is implemented and tested, and a practical example is presented.