플랜트 건조에서 경량모델 기반 용접선 생성 방법

권기연(Ki-Youn Kwon) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.05

선박 및 해양 구조물 곡부재 치수 품질 관리를 위한 가공완성도 평가

권기연(Ki-Youn Kwon),이재용(Jaeyong Lee) 한국해양공학회 2018 韓國海洋工學會誌 Vol.32 No.2

The forward and afterward parts of ships and offshore structures are designed to improve the fuel consumption performance. These are made of curved plates with a large thickness. If a fabricated curved plate has some dimensional errors, a lot of additional cost is incurred in the assembly process. Thus, an accurate dimensional assessment is very important for fabrication. In this paper, we propose an assessment method for the dimensional quality management of curved plates. This can be applied to data measured using a variety of three-dimensional instruments, with boundary measurement points automatically classified and sorted to create a measurement surface. The assessment is evaluated after matching the CAD surface and the measured surface considering constrained conditions. The fabrication assessment is evaluated as a probability of how much the tolerance is satisfied.

중수골 골절에 대한 최소 침습적 고정 방법

권기연 ( Ki Youn Kwon ),오진록 ( Jin Rok Oh ),곽지웅 ( Ji Woong Kwak ) 대한골절학회 2022 대한골절학회지 Vol.35 No.1

목적: 이 연구의 목적은 최소 침습적인 고정 방법인 K-강선 고정술 또는 골수강내 무두나사 고정술을 시행한 중수골 골절 환자에 대해 영상학적, 임상적 결과를 비교분석하는 데 있다. 대상 및 방법: 중수골 중위 및 원위간부 또는 경부 단순 골절에 대해 K-강선 또는 무두나사를 이용해 내고정을 하여 치료하였던 18세에서 55세 사이의 환자들 중 최소 6개월 이상 추시가 가능했던 환자들 52예(남자 46예, 여자 6예)에 대해 영상학적 평가(각변형, 단축), 수부 기능 평가(TAM, 악력, 환자의 주관적 기능 평가), 일상 및 직장으로의 복귀 시간, 합병증의 발생 빈도 등의 요소에 대해 비교분석하였다. 결과: 영상학적 평가, 수부 기능 평가, 합병증의 발생빈도의 측면에서 K-강선 고정군과 골수강내 무두나사 고정군 간 통계적인 차이는 없었으나(p>0.05), 일상 및 직장으로의 복귀는 골수강내 고정군이 빨랐다(p<0.05). 결론: 6개월 이상의 추시에서 중수골 골절에 대한 최소 침습적 치료법인 경피적 K-강선 고정술 및 골수강내 무두나사 고정술은 임상적 결과의 측면에서 차이가 없으나, 일상 및 업무로의 조기 복귀라는 측면에서는 골수강내 무두나사 고정술의 선택을 고려해 볼 만하다. Purpose: This study compared the radiologic and clinical outcomes of metacarpal fractures treated with two minimally invasive surgical techniques: Kirschner wire (K-wire) fixation and headless screw fixation. Materials and Methods: This study included 52 patients (46 males and 6 females; age 18-55 years) with distal metacarpal fractures (middle and distal shaft, including the neck) who had undergone K-wire fixation or headless screw fixation. All subjects were followed up for at least six months. The radiologic assessments were performed to evaluate the angular deformity and shortenings. The total active motion (TAM), grip strength, and patients’ subjective functional assessment were measured to evaluate the hand function. The time taken to return to work (RTW) and adverse events were analyzed. Results: Of the 52 cases, metacarpal fractures treated with headless screw fixation and K-wire fixation showed a significant difference associated with early RTW (p< 0.05). There were no significant differences between the subjects treated with K-wire fixation and those with headless screw fixation in terms of the radiologic measurement, hand function examinations, complications, and adverse events (p >0.05). Conclusion: After a six-month follow-up, minimally invasive K-wire fixation and headless screw fixation produced similar clinical and radiologic outcomes in subjects with metacarpal fractures. Compared to K-wire fixation, however, headless screw fixation led to earlier functional recovery and might be a better option for treating metacarpal fractures in this regard.

형상 가시화를 위한 경량 파일 포맷 연구

권기연(Ki-Youn Kwon) (사)한국CDE학회 2018 한국CDE학회 논문집 Vol.23 No.3

A lightweight model is widely used for visualizing and sharing large data in product lifecycle management (PLM). This model is mainly composed of triangular elements to minimize the file size and increase visibility. The lightweight files are frequently converted due to design changes. Files are kept in a server for efficient management. Users need to download files from the server and it takes a lot of time if the file size is large. We propose a method to reduce the file size of a lightweight file for saving download time. The normal direction of a node is required for visualization, it has a lot of data sizes. The normal direction is restored quickly without saving in the file and the file size is also reduced by recycling the triangle information for the symmetric structures and the same shapes. This proposed method has been tested on several models to demonstrate the feasibility.

경량 모델의 삼각 요소망으로부터 경계 곡선 추출 방법

권기연(Ki-Youn Kwon) (사)한국CDE학회 2017 한국CDE학회 논문집 Vol.22 No.1

Sharing of CAD data plays a key role in the PLM and a lightweight model is widely used for visualizing and sharing a large data. The lightweight model is mainly composed of triangular elements to minimize file size. There is no problem at all to visually confirm the shape based on these triangular elements but there is a limit to numerically calculate the exact position on the curve or surface. In this paper, a boundary curve generation method using triangular elements is proposed to increase the utilization of lightweight models. After matching connectivity of triangular elements, boundary element edges are extracted. Boundary curves are generated by connecting of these boundary element edges. This proposed method has been tested on several models to demonstrate the feasibility.

대용량 포인트 데이터를 활용한 플랜트 구조물 오차 분석 및 형상복원

권기연(Ki Youn Kwon) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.6

선박 곡부재 계측 포인트에 대한 곡면 모델링 방법

권기연(Ki-Youn Kwon),김병철(Byung Chul Kim) (사)한국CDE학회 2020 한국CDE학회 논문집 Vol.25 No.3

Forward and afterward parts of ship and offshore structures are composed of curved plates with a thick thickness. It takes mush time to process the curved plate. If the fabricated curved plate has some dimensional errors, the additional cost is incurred in the assembling process. So, it is important to assess accurate dimensions for fabrication. Recently, photometric systems and 3D laser scanners have been used for this purpose. The dimensional assessment for fabrication is evaluated by comparing the surface created from the measurement points with the design surface. A B-spline surface interpolation is generally used to create the measurement surface, but there may be errors depending on the number and position of measurement points. In this study, we propose a method to improve the generation of the measurement surface. The mesh refinement method is used to obtain an accurate curved surface using a small number of measurement points. A Hermite curve interpolation is applied to reduce the error of the final generated surface. For accurate interpolation, the exact tangential direction is calculated at the vertex of an element, and errors are evaluated for various calculation methods.

선박 건조 치수품질 관리를 위한 계측시스템 적용현황 연구

권기연(Ki-Youn Kwon) (사)한국CDE학회 2017 한국CDE학회 논문집 Vol.22 No.3

A ship is constructed by assembling blocks and installing outfits in assembled ship structures. So, it is important to control dimensional errors occurring during a shipbuilding process. In order to prevent repairing and reworking, a dimensional quality management is needed as follows: the FAT (factory acceptance test) of manufactured parts and outfits, inspection of modular structures, inspection of outfit installations and positioning control of assembly module. Many 3D measurement instruments are being utilized for dimensional inspections. This paper summarizes the applications and main features of 3D measurement instruments for ship construction.

걸음걸이 인식을 통한 연령 및 성별 분류 방법

유현우(Hyun Woo Yoo),권기연(Ki Youn Kwon) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.11

얼굴 모양 및 목소리를 이용하는 방법을 포함하여 연령 및 성별을 분류하는 다양한 방법이 연구되고 있다. 그러나 얼굴 기반 방법은 원거리에서 인식률이 급격히 감소하고, 오디오 기반 방법은 잡음이 많은 환경에서는 적용하기 어렵다. 대조적으로 보행 기반 방법은 대상자가 카메라에 촬영만 되면 인식이 가능하다. 기존 연구에서 카메라의 시점은 측면에서만 볼 수 있어서 실제 환경에서 일반 보행과는 현실적으로 차이가 발생했다. 본 연구에서는 일반 보행 데이터를 이용하여 연령과 성별을 분류할 수 있도록 RGB-D 센서로부터 획득된 골격 모델을 이용한 특징 추출 방법을 제안한다. 실험 결과는 제안된 방법이 실제 환경에서 효율적임을 보여준다. Classification of age and gender has been carried out through different approaches such as facial-based and audio-based classifications. One of the limitations of facial-based methods is the reduced recognition rate over large distances, while another is the prerequisite of the faces to be located in front of the camera. Similarly, in audio-based methods, the recognition rate is reduced in a noisy environment. In contrast, gait-based methods are only required that a target person is in the camera. In previous works, the view point of a camera is only available as a side view and gait data sets consist of a standard gait, which is different from an ordinary gait in a real environment. We propose a feature extraction method using skeleton models from an RGB-D sensor by considering characteristics of age and gender using ordinary gait. Experimental results show that the proposed method could efficiently classify age and gender within a target group of individuals in real-life environments.

기하공차에서 공차적층분석을 통한 공차의 조정

김경욱(Kyung-Wook Kim),권기연(Ki-Youn Kwon),장성호(Sung-Ho Chang) (사)한국CDE학회 2017 한국CDE학회 논문집 Vol.22 No.4

One of the challenges facing precision manufacturers is the increasing feature complexity of tight tolerance parts. Tolerance is an essential part of design and manufacturing. For tolerance analysis, most common methods are worst case method, statistical method and Monte Carlo Simulation method. These methods do a good job for dimensioning and tolerancing of size and are still used in good capacity. But these methods do not cater precisely for geometrical tolerances. The main limitations of these methods are the following: they do not properly support the application of the envelope rule and of the independence rule to different dimensional tolerances on the same part as prescribed by the standards. A stack is a calculation which determines the maximum or minimum distance (clearance or interference) between two features on a part or in an assembly. Therefore we tried to propose for the development of a new method aimed at addressing such limitations. Tolerance stack of individual components and their assembly have been carried out using graphical approach. Based on the stack tolerance, it can be verified with the design tolerance of the assembly. Based on the comparison, designer has to reassign the appropriate tolerances to fulfil the functionality if required.