• Journal of Aerospace System Engineering
• /
• v.16 no.3
• /
• pp.63-72
• /
• 2022

The purpose of this paper was to understand the dynamics of deployment of large mesh antennas, and to provide a numerical method for determining the dynamic stiffness and the driving forces for the design. The deployment structure was numerically modeled using the frame elements. The eigenvalue analysis was demonstrated, with respect to the folded and unfolded configurations of the antenna. A multibody dynamic model was formulated with Kane's equation, and simulated using the pseudo upper triangular decomposition (PUTD) method for resolving the constrained problem. Based on the multibody model, the kinetics of the deployment, the motor driving forces, and the feasibility of the designed deployment structure were investigated.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.50 no.5
• /
• pp.211-217
• /
• 2001

In this paper, we have developed the 6 DOF force display system to be based on the single PC. The system is composed of the force display device, the force reflecting rendering algorithm and the high-speed controller. The previous systems had a problem, that must adopt high performance workstation or 2-PC in order to control the graphics speedily and stably. In this paper, it is possible to improve the problem as to develop its exclusive controller and new rendering algorithm. The proposed new rendering algorithm is based on the Proxy algorithm, which can convert information of the position, the velocity, and the haptic information into the force-data. Especially, as to use the proxy algorithm, we can construct dynamical virtual-environment with the elasticity, the viscosity, the mass, and the friction force. As the result of the experiment, we found that our system has much superior characteristics than some other haptic interfaces, because it can control of 30,000 polygon model constructed virtual object with 1[kHz] haptic interrupt cycle and 20[Hz] graphic interrupt cycle in the single PC based system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.710-713
• /
• 2005

Many impact or drop test researches of home appliances are published, but those of toys cannot be found easily. External impacts are the primary causes of fracture of toys. For impact proof design, the finished product should pass an impact test after molding design. There are several international toy safety standards or requirements such as US CPSC(Consumer Product Safety Commission), ASTM F963-96a, EN71 and so on. The puppy robot which patrols around the house, namely, the watchdog was selected to investigate toy safety because it has considerable weight and outer panels are made of plastics. First the model of watchdog robot was obtained by 3 dimensional scan. Surface data can be generated from 3D polygon data of the watchdog. A reliable drop simulation method for the watchdog was established using Pam-crash program according to Korean toy safety standards. When there is a low impact allowance value, the molding design should be reinforced or changed. It was found that the maximum impact stress reaches the ultimate stress of panel material.

• 한국HCI학회:학술대회논문집
• /
• 2006.02a
• /
• pp.266-274
• /
• 2006

본 논문은 새로운 햅틱 API 인 "K-Touch"의 개발에 관한 것이다. 그래픽 하드웨어 기반의 핵심 역감 알고리즘을 기반으로 개발된 K-Touch API 는 가상 환경을 구성하는 다양한 데이터 형식(3D polygon model, volume data, 2.5D depth image)에 대한 햅틱 상호작용을 가능하게 하고, 새로운 햅틱 알고리즘 및 장치 개발에 필요한 소프트웨어 확장성을 제공함과 동시에 사용자가 쉽고 빠르게 햅틱 응용분야를 개발할 수 있도록 설계되었다. 아울러 햅틱 감각의 중요 요소인 역감 및 촉감 상호작용을 위해 기존의 햅틱 SDK 및 API 와 달리 역/촉감을 동시에 제시할 수 있는 알고리즘이 개발되었다. 본 논문에서 제안하는 새로운 햅틱 API 의 효용성을 검증하기 위해 다양한 응용분야의 예를 구현하였다. 새로운 햅틱 API 인 K-Touch 는 사용자 및 연구자에게 보다 효율적으로 햅틱 연구를 진행 할 수 있도록 도움을 주는 툴(Tool)로써 중요한 역할을 할 것으로 기대된다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.8 no.2
• /
• pp.198-208
• /
• 2016

The painting process of large ships is an intense manual operation that typically comprises 9-12% of the total shipbuilding cost. Accordingly, shipbuilders need to estimate the required amount of anti-corrosive coatings and painting resources for inventory and cost control. This study aims to develop a software system which enables the shipbuilders to estimate paint area using existing 3D CAD ship structural models. The geometric information of the ships structure are extracted from the existing shipbuilding CAD/CAM system and used to create painting zones. After specifying the painting zones, users can generate the paint faces by clipping structural parts inside each zone. Finally, the paint resources may be obtained from the product of the paint areas and required paint thickness. Implementing the developed software system to real shipbuilders' operations has contributed to improved productivity, faster resource estimation, better accuracy, and fewer coating defects over their conventional manual calculation methods for painting resource estimation.

• Korean Journal of Computational Design and Engineering
• /
• v.16 no.5
• /
• pp.315-322
• /
• 2011

The goal of total knee replacement (TKR) surgery is to replace patient's knee joint with artificial implants in order to restore normal knee joint functions. Since mismatched knee implants often cause a critical balancing problem and short durability, designing a well-fitted implant to a patient's knee joint is essential to improve surgical outcomes. We developed a software system that three-dimensionally (3D) simulates TKR surgery based upon 3D knee models reconstructed from computed tomography (CT) imaging. The main task of the system was to extract precise 3D anatomical parameters of a patient's knee that were directly used to determine a custom fit implant and to virtually perform TKR surgery. The virtual surgery was simulated by amputating a 3D knee model and positioning the determined implant components on the amputated knee. The test result shows that it is applicable to derive surgical parameters, determine individualized implant components, rehearse the whole surgical procedure, and train medical staff or students for actual TKR surgery. The feasibility and verification of the proposed system is described with examples.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.8 s.227
• /
• pp.1116-1124
• /
• 2004

In these days, a vehicle simulator has been developed with a VR(Virtual Reality) system. A VR system must provide a vehicle simulator with natural interaction, sufficient immersion and realistic images. In addition, a VR system must present a driver with the realistic driving situation. To achieve these, it is important to obtain a fast and uniform rendering performance regardless of the complexity of virtual worlds. In this paper, the factors to improve the reality for the VR based vehicle simulator have been investigated. For the purpose, the modeling and the rendering methods which offer an improved performance for complex VR applications as the 3D road model have been implemented and verified. Then, we experiment on the influence of graphic and sound factors to the driver, and analyze each result for improving the reality such as the driver's viewport, the form of texture, the lateral distance of the side object, and the sound effect. These factors are evaluated on the driving system which is constructed for qualitative analysis. The research results could be used for improving the reality of the VR based vehicle simulator.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2006.11a
• /
• pp.59-62
• /
• 2006

본 논문에서는 OpenGL Rendering을 이용한 모델기반 3D 다시점 영상의 객체 구현을 위한 구성과 각 모듈에 적용되는 알고리즘에 대해 중점적으로 연구하였다. 한 장의 텍스쳐 이미지와 깊이 맵(Depth Map)을 가지고 다시점 객체를 생성하기 위해, 먼저 깊이 정보의 전처리 과정을 거친다. 전처리 된 깊이 정보는 OpenGL상에서의 일정 간격의 꼭지점(Vertex) 정보로 샘플링 된다. 샘플링 된 꼭지점 정보는 깊이 정보를 z값으로 가지는 3차원 공간 좌표상의 점이다. 이 꼭지점 정보를 기반으로 텍스쳐 맵핑 (texture mapping)을 위한 폴리곤(polygon)을 구성하기 위해 딜루이니 삼각화(Delaunay Triangulations) 알고리즘이 적용되었다. 이렇게 구성된 폴리곤 위에 텍스쳐 이미지를 맵핑하여 OpenGL의 좌표 연산을 통해 시점을 자유롭게 조정할 수 있는 객체를 만들었다. 제한된 하나의 이미지와 깊이 정보만을 가지고 좀 더 넓은 범위의 시점을 가지는 다시점 객체를 생성하기 위해, 새로운 꼭지점을 생성하여 폴리곤을 확장시켜 기존보다 더 넓은 시점을 확보할 수 있었다. 또한 렌더링된 모델의 경계 영역 부분의 깊이정보 평활화를 통해 시각적인 개선을 이룰 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.04a
• /
• pp.83-86
• /
• 2002

최근 지리 정보 시스템이나 공간 데이터 베이스 시스템이 발전하면서 실세계를 효율적으로 모델링하려는 맡은 연구가 수행되고 있다. 기존의 단순한 point, line, polygon으로 모델링했던 방법들을 multipoint, multiline, multipolygon과 같은 복잡한 객체를 표현하기 위한 연구로 확장되었다. 또한 이러한 공간 객체의 이력을 효율적으로 관리하기 위해 공간 객체를 시간으로 확장하는 연구가 수행되고 있다. 이러한 모델들은 명확한 경계를 가진 시공간 객체를 대상으로 한다. 자연, 사회 문화 현상, 생태 같은 경계가 명확하지 않은 객체를 단순한 경계를 가진 공간 객체로 모델링하기에는 그 표현력이 부족하다. 따라서 이 논문에서는 이런 문제점을 해결하기 위해서 불확실한 경계를 가진 시공간 데이터 모델을 제시한다. 이 논문에서 제시한 불확실한 경제를 가진 시공간 모델의 설계는 상호 운용을 증진하기 위하여 OGC(OpenGIS Consortium)에서 제시한 2차원 기하 객체 모델을 기반으로 불확실한 경계를 가지는 공간 데이터 모델로 확장한다. 또한, 이 불확실한 경계를 가지는 단순한 공간 모델을 시간 영역으로 확장하여 유효시간을 갖는 불확실한 시공간 데이터 모델을 설계한다. 또한, 이 논문에서 제시한 불확실한 경계를 가진 시공간 객체 모델을 바탕으로 실세계의 다양하고 복잡한 객체에 대한 효율적인 질의가 가능한 시공간 연산자를 제시한다.

• Journal of Electrical Engineering and Technology
• /
• v.3 no.2
• /
• pp.152-161
• /
• 2008

This paper deals with a new wave shaping technique for cost effective harmonic mitigation in ac-dc converter feeding Vector Controlled Induction Motor Drives(VCIMD's) for improving power quality at the point of common coupling(PCC). The proposed harmonic mitigator consists of a polygon connected autotransformer based twelve-pulse ac-dc converter and a small rating passive shunt filter tuned for $11^{th}$ harmonic frequency. This ac-dc converter eliminates the most dominant $5^{th},\;7^{th},\;and\;11^{th}$ harmonics and imposes the reduction of other higher order harmonics from the ac main current, thereby improving the power quality at ac mains. The design of autotransformer is carried out for the proposed ac-dc converter to make it suitable for retrofit applications, where presently a 6-pulse ac-dc converter is used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter in a wide operating range of the drive. Experimental results obtained on the developed laboratory prototype of the proposed harmonic mitigator are used to validate the model and design of the ac-dc converter.